distribution system capability statement - mzec.nama.om · distribution system capability statement...
TRANSCRIPT
DISTRIBUTION SYSTEM
CAPABILITY
STATEMENT [Document subtitle]
Abstract [Draw your reader in with an engaging abstract. It is typically a short summary of the
document. When you’re ready to add your content, just click here and start typing.]
Distribution System
Capability Statement
2018-2020
إحدى شركات مجموعة نماء
Member of Nama Group
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | i
20
18
-
2
02
0
Foreword
Although every effort has been made to ensure the accuracy of the data provided in this statement,
Mazoon Electricity Company SOAC (MZEC) does not accept any liability for the accuracy of the
information contained herein, and in particular neither MZEC nor its directors or its employees shall
be under any liability for any misstatement or opinion on which the recipient of this statement relies
or seeks to rely.
No part of this Statement may be reproduced, stored in a retrieval system, transmitted or further
distributed in any form or means electronic, mechanical, photocopying, recording or otherwise for
any purpose other than with the written permission of MZEC.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | ii
20
18
-
2
02
0
Company Profile
The electricity sector in the Sultanate of Oman has been extensively restructured following the
implementation of the law for the regulation and privatization of the electricity and related water
sector ("The Sector Law"). The Sector Law was promulgated by Royal Decree 78/2004 on 1 August
2004. The law provided for the unbundling of the electricity and related water activities previously
undertaken by the Ministry of Housing, Electricity and Water (MHEW).
A number of successor companies are authorized by licenses issued by the Authority for Electricity
Regulation, Oman to undertake certain regulated activities.
Mazoon Electricity Company SAOC (MZEC) is one of Nama Groups and is authorized to undertake
the regulated activities of distribution and supply within the authorized area stipulated in its License.
It serves a large supply area of almost 75000 km2 in the north-east corner of Oman. MZEC’s supply
area is split into four governorates which are Al Dakhilyiah (to the central-north of Oman), North Al
Sharqiyah and South Al Sharqiyah (the coastal region to the Eastern part of Oman) and South Al
Batinah and Wilayat of Suwaiq (the coastal region to the north-east of Oman). In this statement the
four governorates will be considered as three supply regions as following: Al Dakhilyiah, Al Sharqiyah
which consists of South Al Sharqiyah Governorate and North Al Sharqiyah Governorate and South
Batinah. Among the Four governorates, South Al Batinah Governorate has the highest number of
customer accounts with estimated supply area of 6260 km2 followed by Al Dakhilyiah with an
estimated supply of 31900 km2 with the second highest number of customer accounts. South Al
Sharqiyah Governorate and North Al Sharqiyah Governorate are the biggest among the four supply
areas with an estimated supply area of 37674 km2 and has the lowest number of customer accounts
as shown in the flow chart below.
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
Al Dakhilyiah North AlSharqiyah
South AlSharqiyah
South AlBatinah
MZEC
116,781
73,811 70,279
145,107
405,978
Customers Account
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | iii
20
18
-
2
02
0
Table of Contents
Foreword ............................................................................................................................................. Company Profile .............................................................................................................................. ii
Introduction ...................................................................................................................................... 1 I Purpose of Statement .............................................................................................................. 1
II Content of Statement .............................................................................................................. 1 IV Contact details for further information............................................................................. 2
Summary Information .................................................................................................................... 3 1. Design Philosophies and Practices ....................................................................................... 3
1.1 Background ............................................................................................................................ 3 1.2 Operational Environment ................................................................................................... 3 1.3 Technical, Design and Operational Criteria .................................................................. 3
1.3.1 Voltage regulation ......................................................................................................... 3 1.3.2 Frequency deviations .................................................................................................. 4
1.3.3 Voltage waveform quality ........................................................................................... 4 1.3.4 Voltage fluctuations ..................................................................................................... 4
1.3.5 Auto-reclosing and single phase Protection Operation ..................................... 4
1.4 Technical standards applying to Distribution System Users ................................... 5 1.4.1 Specific design and performance standards ........................................................ 5
1.4.1.1 Specification of apparatus and Plant ............................................................... 5
1.4.1.2 Earthing .................................................................................................................... 6
1.4.1.3 Voltage control and regulation .......................................................................... 6 1.4.1.4 Protection................................................................................................................. 6
1.4.1.5 Superimposed signals .......................................................................................... 7
1.5 General requirements for Connection ............................................................................ 7 1.5.1 Declaration of Demand characteristics ................................................................... 7
1.5.1.1 Supplies at Low Voltage ...................................................................................... 7 1.5.1.2 Supplies other than at Low Voltage .................................................................. 7
1.5.2 Connection arrangements .......................................................................................... 8 1.5.3 Electrical Delivery Points ............................................................................................ 8
1.5.4 Communications ........................................................................................................... 8
1.6 Technical requirements for Connections ...................................................................... 9 1.6.1 Apparatus and Plant at the ownership boundary................................................. 9
1.6.2 Protection requirements ............................................................................................. 9 1.6.3 Earthing ........................................................................................................................... 9
1.6.4 Fault level considerations .......................................................................................... 9 1.6.5 Capacitive and inductive effects ............................................................................... 9
1.6.6 Telemetry ....................................................................................................................... 10
1.7 Requirements for Embedded Gensets ......................................................................... 10 1.7.1 General requirements ................................................................................................ 10
1.7.2 Provision of information ........................................................................................... 10 1.7.3 Information required from all Embedded Gensets ............................................ 11
1.7.4 Additional information required from some Embedded Gensets .................. 11
1.7.5 Technical requirements ............................................................................................. 11
1.7.5.1 Genset performance requirements ..................................................................... 11
1.7.5.2 Control arrangements ............................................................................................ 12 1.7.5.3 Coordinating with existing protection .................................................................. 12
1.7.5.4 Islanding ................................................................................................................. 12 1.7.5.5 Black Start capability .......................................................................................... 13
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | iv
20
18
-
2
02
0
1.7.5.6 Genset commissioning tests ............................................................................ 13
2. The 33 kV System ..................................................................................................................... 13 2.1 System Configuration ....................................................................................................... 13
2.2 System Security .................................................................................................................. 14 2.3 Selection and Application of Plant ................................................................................ 14
2.3.1 Transformers ................................................................................................................ 14
2.3.2 Switchgear .................................................................................................................... 14 2.3.3 Overhead Lines ............................................................................................................ 15
2.3.4 Underground Cables .................................................................................................. 15 2.3.5 Short Circuit Levels .................................................................................................... 15
2.3.6 Protection ...................................................................................................................... 15
3. The 11 kV System ..................................................................................................................... 15 3.1 System Configuration ....................................................................................................... 15
3.2 System Security .................................................................................................................. 16 3.3 Selection and Application of Plant ................................................................................ 16
3.3.1 Distribution Substations ........................................................................................... 16
3.3.2 Overhead lines ............................................................................................................. 16
3.3.3 Underground Cables .................................................................................................. 17 3.3.4 Short Circuit Levels .................................................................................................... 17 3.3.5 Protection ...................................................................................................................... 17
4. The Low Voltage System ........................................................................................................ 17
4.1 System Configuration ....................................................................................................... 17
4.3 Selection and Application of plant................................................................................. 17 4.3.1 Distribution Substations ........................................................................................... 17
4.3.2 Overhead Lines ............................................................................................................ 18
4.3.3 Underground Cables .................................................................................................. 18 4.3.4 Protection ...................................................................................................................... 18
5. Operating Voltage ..................................................................................................................... 18 6. Load Management Areas ........................................................................................................ 18
7. Other Interconnected Networks ............................................................................................ 18 8. The 33 kV System Load Flow Study .................................................................................... 19
8.1 Introduction .......................................................................................................................... 19 8.2 Purpose of the Study ......................................................................................................... 19
8.3 The 33 kV Distribution Network ...................................................................................... 19
8.4 The Load Flow Analysis ................................................................................................... 20 8.5 Presentation of Results and Single Line Diagrams for the Years 2018-2020 .... 20
9. The 33 kV Short Circuit Analysis .......................................................................................... 20 10. Voltages Non Compliance .................................................................................................... 21
11. Distribution System Security Standards (DSSS) ........................................................... 21 12. Demand Forecast ................................................................................................................... 22
12.1 Introduction ....................................................................................................................... 23
12.2 Load Curves....................................................................................................................... 24 12.3 Demand forecast Methodology .................................................................................... 26
13. Future System Development Projects .............................................................................. 29
14. Assessment of 33 KV Technical Losses .......................................................................... 37
15. Network Suitability for New Connections ........................................................................ 37
16. Constraints ............................................................................................................................... 38
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | v
20
18
-
2
02
0
Lists of Tables
Table 1: Voltage Regulation ........................................................................................................................................... 4
Table 2: Number of 33/11.5 kV transformers up to September 2017 .................................................................... 14
Table 3: Current Ratings of Bus Bar, Bus-section, Transformer and Feeder Bays ............................................ 15
Table 4: Number of distribution transformer until September 2017 ........................................................................ 16
Table 5: MZEC’s operating voltages ........................................................................................................................... 18
Table 6: Distribution System Security Standards ...................................................................................................... 22
Table 7: Peak Demand in MW of Corporate Projects by Customer Category expected in 2018-2020 ............ 28
Table 8: MZEC coincident after diversity and load factor ........................................................................................ 28
Table 9: 33 KV Projects for Al Dakhilyiah 2018-2020............................................................................................... 30
Table 10: 33 KV Projects for South Al Sharqiah 2018-2020 ................................................................................... 31
Table 11: 33 KV Projects for South Batinah 2018-2020 .......................................................................................... 32
Table 12: 33 KV Projects for North Al Sharqiah 2018-2020 .................................................................................... 33
Table 13: Sponsor Project in Al Dakhiyah .................................................................................................................. 34
Table 14: Sponsor Project in South Al Sharqiah ....................................................................................................... 34
Table 15: Sponsor Project in South Batinah ...................................................................................................................... 35
Table 16: Sponsor Project in North Sharqiah ............................................................................................................ 36
Table 17 : MZEC’s Total Demand and 33 KV Network Losses 2018-2020 .......................................................... 37
Lists of Figures
Figure 1: MZEC peak load ............................................................................................................................................ 24
Figure 2: The Load Profile of MZEC ........................................................................................................................... 24
Figure 3: Weekly Load Profile ...................................................................................................................................... 25
Figure 4: MZEC Yearly Load Profile 2016 (Jan-Oct) ................................................................................................ 25
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 1
20
18
-
2
02
0
Introduction
I Purpose of Statement This Capability Statement is prepared in accordance with the Distribution & Supply License Condition
32: Distribution System Capability Statement and Clause DPC.4.4 (Three Year Capability
Statement) of the Distribution Planning Code to assist existing and future users of MZEC’s network
in examining opportunities available to them to make new or additional use of the network.
The aim of the Three Year Capability Statement is to:
1) Improve the availability of distribution network information.
2) Furnish developers with sufficient information to carry out initial assessments of network
capability.
3) Inform users of distribution network about development proposals.
II Content of Statement The statement contains information regarding the 33 kV and 11 kV systems and the transformation
level to 11 kV that are owned and operated by MZEC. Some of the requirements for the connection
to the Distribution System derived from the {Distribution Code – Distribution Connection
Conditions Code (DCC)}, design philosophies employed by MZEC, general description of MZEC’s
Distribution System are included in the Summary Information section.
Introduction
An overview of the Long Term Development Statement intended to enable users and potential users
of the network to understand the scope of the information provided and to assess if it would be of
use to them.
Summary Information
This is a general description of the design philosophies and practices appropriate to the whole of the
distribution network.
Load Flow Study of the 33 kV Network
A general and brief description of the load flow study analysis carried on MZEC’s 33 KV network
using ETAP software is presented in this part of the statement.
Short Circuit Study of the 33 kV Network
A brief outlining of the short circuit study analysis results conducted on the 33 KV networks of the
four Governorates are presented.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 2
20
18
-
2
02
0
Voltage Non-Compliance
Non-compliance towards the voltage standards is presented for the 33 kV bus bars at the primary
substations only is addressed in section 10.
Distribution System Security Standards (DSSS)
After the approval of the Distribution System Security Standards in November 2008, compliance with
the planning standards has become a compulsory issue. This is presented in section 11.
Load Curves
Sample graphs of MZEC’s load curve (yearly, weekly and daily) are presented in section 12.
Future System Development Projects
These development statements for the four Governorates Al Dakhilyiah, North Al Sharqiyah, South
Al Sharqiyah and South Al Batinah governorates are presented in a detailed form in section 13.
IV Contact details for further information
Requests for a copy or even copies of this Capability Statement or for assistance in interpretation
and clarification of the information contained in the statement should made to:
Senior Planning & Asset Management Manager
Mazoon Electricity Company SAOC
P.O. Box 1229
P.C. 131, Al-Hamriya
Sultanate of Oman
E-Mail: [email protected]
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 3
20
18
-
2
02
0
Summary Information
1. Design Philosophies and Practices
1.1 Background
Mazoon Electricity Company SAOC (MZEC) has a functional philosophy that underlies the
development of the distribution system at the three voltages 33, 11 and 0.415 kV. This ensures that
the whole distribution system satisfies the following fundamental design criteria throughout the
planning period:
1) Compliance with all legal and statutory requirements,
2) Compliance with all regulatory requirements, including the Grid Code and the Distribution Code,
3) Compliance with all relevant national and international standards,
4) Ability to meet the demands placed upon it in terms of customer requirements, supply
performance (availability and reliability) and supply quality (voltage and waveform quality).
The distribution system must also be capable of being operated, maintained, repaired, extended and
replaced as necessary during its life, without exceeding design levels of risk to the customers it
serves.
1.2 Operational Environment
The distribution system has to be designed such that it is capable of continuous operation under the
range of climatic conditions that can be reasonably expected in the geographic region covered by
MZEC’s distribution system.
1.3 Technical, Design and Operational Criteria
The Distribution System and any Distribution System User Connections to the Distribution System
shall be designed to be consistent with the security requirements of Condition 31 of the Distribution
and Supply License.
MZEC will ensure that the Distribution System complies with the following technical, design and
operational criteria in relation to the part of the Distribution System at the Connection Site with a
Distribution System User.
1.3.1 Voltage regulation
The voltage on the 33 kV and 11 kV sides of Distribution transformers at Connection Sites with
Distribution System Users shall normally be controlled within the limits± 6%of the nominal value.
During some System Disturbances such as where short circuits occurs, the voltage may collapse
transiently to zero at the point of fault until the fault is cleared.
Under fault and circuit switching conditions the 50.00Hz Frequency component of voltage may fall
or rise transiently. The fall or rise in voltage will be affected by the method of earthing of the neutral
point of the Distribution System and this variation in voltage shall be taken into account in selecting
apparatus and Plant from an appropriate specification for installation or Connection to the System.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 4
20
18
-
2
02
0
The voltage at the Consumer’s terminals shall not vary from the System nominal voltage by more
than (see Table 1)
Table 1: Voltage Regulation
Consumers Connected at Nominal Voltage Tolerance
HV 33/11 kV ± 6%
LV 415/240 V ± 6%
1.3.2 Frequency deviations
During normal operating conditions, the nominal System Frequency of the Transmission and
Distribution Systems will be 50.00 Hz and normally will be controlled by Oman Electricity
Transmission Company (OETC) between 49.95Hz and 50.05Hz. During exceptional steady state
conditions, Frequency deviations will not exceed 49.90Hz to 50.10Hz unless disturbed
circumstances prevail. Under disturbed conditions, System Frequency could rise transiently to 51.50
Hz or fall to 48.00 Hz.
1.3.3 Voltage waveform quality
All apparatus and Plant Connected to the Distribution System, and that part of the Distribution
System at each Connection Point, should be capable of withstanding the following distortions of the
voltage waveform in respect of harmonic content and phase unbalance.
The maximum total levels of harmonic distortion on the Distribution System at, 33 kV and 11 kV,
from all sources under both normal, planned outage and fault outage conditions, shall not exceed a
total harmonic distortion of 2.0 % with no individual harmonic greater than 1.5 % unless abnormal
conditions prevail. At LV the maximum total levels of harmonic distortion from all sources shall not
exceed a total harmonic distortion of 2.5 %.
The maximum negative phase sequence component of the phase voltage on the Distribution System
should remain below 1.0 % unless abnormal conditions prevail. A maximum value of 2.0 % is
permitted for phase unbalance.
1.3.4 Voltage fluctuations
Voltage fluctuations arising from fluctuating Demands Connected at a Connection Point to the
Distribution System shall not exceed 1.0% of the voltage level for step changes that may occur
repetitively. Any large voltage excursions other than step changes may be allowed up to a level of
3.0% provided that this does not constitute a risk to the Distribution System or to any Distribution
System User.
1.3.5 Auto-reclosing and single phase Protection Operation
Distribution System Users should be aware that MZEC may use auto-reclosing or sequential
switching features on the Distribution System. MZEC will on request provide details of the auto-
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 5
20
18
-
2
02
0
reclosing or sequential switching features in order that the Distribution System User may take this
into account in the design of the User’s Distribution System, including Protection arrangements.
Distribution System Users should be aware that the Protection arrangements on some Distribution
Systems may cause disconnection of one phase or two phases only of a three phase Supply for
certain types of fault.
1.4 Technical standards applying to Distribution System Users
All Distribution System User apparatus and Plant associated with the Connection to the Distribution
System shall comply with the following standards, as applicable (in the following order of
precedence):
(a) Safety Rules;
(b) Oman Electrical Standards (OES), which are such national standards as may be
amended by the Distribution Code Review Panel from time to time and approved by Authority
for Electricity Regulation, Oman “the Authority” or which are imposed under the Sector Law;
(c) The standards and recommendations of the International Standards Organization and the
International Electro technical Commission; and
(d) National standards and codes which are accepted internationally.
Further advice will be made available upon request to MZEC.
In the event that any standard or specification with which a Distribution System User’s Plant and/or
apparatus is required to comply under DCC.5 is amended, MZEC, having consulted with the affected
Distribution System Users, will bring the issues to the Distribution Code Review Panel for
consideration. Following the review, the Distribution Code Review Panel will make a
recommendation to the Authority for approval as to what action, if any, should be taken regarding
compliance.
Where MZEC determines that in order to ensure safe and coordinated Operation of a Distribution
System User’s Plant and/or apparatus with the Distribution System, there is a requirement for
supplemental specifications and/or standards to apply to the design of a Distribution System User’s
Plant and/or apparatus, MZEC shall notify the Distribution System User and the Distribution System
User shall comply with the additional requirements. On request from the Distribution System User,
a Licensed Distributor shall provide reasonable evidence as necessary to demonstrate the need for
the supplemental specifications and/or standards. If a Distribution System User is still not satisfied,
the Distribution System User may refer the issue to the Distribution Code Review Panel for review.
1.4.1 Specific design and performance standards
1.4.1.1 Specification of apparatus and Plant
The specifications of apparatus and Plant shall be such as to permit operation of the Distribution
System within the Safety procedures of MZEC, details of which will be made available by MZEC
upon request.
Apparatus and Plant shall be suitable for use at the operating Frequency, within the intended
operating voltage range and at the design short-circuit rating of the Distribution System to which it is
Connected having due regard to fault carrying capabilities and making and breaking duties. In
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 6
20
18
-
2
02
0
appropriate circumstances, MZEC will provide details of the System to which Connection is to be
made.
Apparatus and Plant shall be operated within the thermal rating conditions contained in the
appropriate standards, specifications, and other relevant publications, taking into account the
intended use. Upon request, MZEC will make such information available.
1.4.1.2 Earthing
MZEC can advise on the method of earthing of the Distribution System, for example, whether it is
connected solidly to Earth or through impedance. The specification of associated apparatus and
Plant of the Distribution System User shall meet the voltages that will be imposed on the apparatus
and Plant as a result of the method of earthing. The methods of earthing should comply with the
requirements of Oman Electrical Standards.
Distribution System Users shall take precautions to limit the occurrence and effects of circulating
currents in respect of the neutral points connected with earth where there is more than one source
of electricity.
1.4.1.3 Voltage control and regulation
Any extension or Connection to the Distribution System shall be designed in such a way that it does
not adversely affect the voltage control employed by MZEC on the Distribution System. MZEC if
requested by the Distribution System User will make information on the voltage regulation and
control arrangements available.
1.4.1.4 Protection
The Distribution System and the System of any Distribution System User Connected to the
Distribution System shall incorporate protective devices to ensure that apparatus and Plant with
electrical faults are disconnected from the System promptly and that the effects of faults on one
System do not impose unreasonable risks to other Systems.
To ensure satisfactory operation of the Distribution System, Protection Systems, operating times,
discrimination, and sensitivity at the ownership boundary shall be agreed between MZEC and the
System User during the process of application for Connection and may be reviewed from time to
time by MZEC with the agreement of the customer. Back-up Protection by Operation of other circuit
breakers or apparatus and Plant having a similar function must normally be provided, to safeguard
the System against a circuit breaker, or apparatus and Plant having a similar function, failing to
Operate correctly to interrupt fault current on a High Voltage System. During the process of
application for connection, MZEC will advise the Distribution System User if Back-up protection is
not required.
Distribution System Users shall not use protection and associated apparatus and plant to limit the
fault current in feed to the Distribution System, if the failure of that protection and associated
apparatus and plant to operate as intended in the event of a fault, could cause apparatus and plant
owned by MZEC to operate outside its short-circuit rating, unless MZEC should advise otherwise.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 7
20
18
-
2
02
0
1.4.1.5 Superimposed signals
Where Distribution System Users install mains-borne signaling apparatus and plant it shall comply
with European Standard EN50065 as amended from time to time. Prior agreement shall be obtained
in writing from MZEC where a Distribution System User proposes to use such apparatus and plant
that may superimpose signals on the Distribution System.
1.5 General requirements for Connection
DCC.6 ensures that all Distribution System Users of the Distribution System are subject to the same
requirements for connection. DCC.6 specifies the information required from Distribution System
Users by MZEC in order to ensure that adequate technical provision is made for new Supplies or
increases in existing Demand. DCC.6 also applies to Gensets that Operate in parallel with the
Distribution System, where a supply is required from MZEC under normal or Emergency Conditions.
1.5.1 Declaration of Demand characteristics
1.5.1.1 Supplies at Low Voltage
For Supplies at Low Voltage it is possible in most cases to assess whether a proposed Connection
is acceptable, and to determine the necessary Supply arrangements, from analysis of the following
limited data:
(i) Maximum power requirements ( kVA or kW and Power Factor);
(ii) Type and electrical loading of apparatus and Plant to be Connected, e.g. number and
size of motors, electrical cooling arrangements; and
(iii) The date when the Connection is required.
These data requirements will be specified on the appropriate application for Connection form
obtainable from MZEC. Should a preliminary examination of this data indicate that more detailed
information is required then it shall be provided to MZEC upon request if reasonably required.
1.5.1.2 Supplies other than at Low Voltage
For Supplies other than at Low Voltage it may be necessary for the following additional information
to be provided on request:
(i) All types of Demand:
(a) Maximum Distribution System User Active Power requirement (MW);
(b) Maximum and minimum Reactive Power requirements (MVAr);
(c) Type of Demand and control arrangements e.g. controlled rectifier or large motor
drives, type of starter employed;
(d) Maximum Demand on each phase at time of maximum Demand; and
(e) The maximum harmonic currents to be imposed on MZEC Distribution System.
(ii) Fluctuating Demands:
Details of the cyclic variation, and where applicable the duty cycle, of Active Power (and Re-active
Power, if appropriate), in particular:
(a) The rates of change of Active and Reactive Power, both increasing and
decreasing;
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 8
20
18
-
2
02
0
(b) The shortest repetitive time interval between fluctuations in Active Power and
Reactive Power; and
(c) The magnitude of the largest step changes in Active Power and Reactive Power,
both increasing and decreasing.
In some cases, more detailed information may need to be provided to permit a full assessment of
the effect of the Demand on the Distribution System. Such information may include an indication of
the pattern of buildup of Demand and a proposed commissioning program. MZEC will specifically
request this information when necessary.
1.5.2 Connection arrangements
The design of Connections between the Distribution System and Distribution System Users shall be
in accordance with the principles set out in the DCC, subject to any modification to which MZEC may
reasonably consent.
During the process of application for Connection MZEC will agree with the Distribution System User
the voltage level to which a Distribution System User will be connected in accordance with its normal
practice for the type of Demand to be supplied. MZEC may on occasion specify a different
Connection voltage from normal in order to avoid potential disturbance caused by the Distribution
System User apparatus to other Distribution System Users of the Distribution System or for other
technical reasons or may agree alternative methods for minimizing the effects of disturbing
Demands.
Before entering into an ECA/ECUOSA it will be necessary for MZEC to be reasonably satisfied that
the Distribution System User’s System at the boundary with the Distribution System will comply with
all appropriate requirements of the Distribution Code.
1.5.3 Electrical Delivery Points
The point or points at which Supply is given or taken will be the Electrical Delivery Points as specified
in the ECA/ECUOSA. For Supplies at Low Voltage the general rule is that the Electrical Delivery
Point will be at the Distribution System User terminals of the Metering System.
For High Voltage Supplies, including Connections between MZEC and Distribution System Users,
and where necessary, bus bar Connected Supplies at Low Voltage, the points of Supply will be the
Electrical Delivery Points as specified in the ECA/ECUOSA. The respective ownership of Plant or
apparatus will be recorded in the ECA/ECUOSA between a MZEC and the Distribution System User
as required. In the absence of a separate agreement between the parties to the contrary,
construction, commissioning, control Operation and maintenance responsibilities follow ownership.
Paragraph DCC.9 specifies responsibilities at the Connection Site.
1.5.4 Communications
Where, for operational reasons, MZEC determines that a means of routine and emergency
communication between MZEC and the Distribution System User is required then the same shall be
provided and maintained by the Distribution System User.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 9
20
18
-
2
02
0
1.6 Technical requirements for Connections
1.6.1 Apparatus and Plant at the ownership boundary
All apparatus and Plant at the ownership boundary shall meet the design principles contained within
DCC.4. Connections for entry to and exit from the Distribution System shall incorporate a means of
disconnection of the installation by MZEC.
1.6.2 Protection requirements
Protection requirements vary widely depending on established practices and the needs of the
particular Distribution System. The basic requirement in all cases is that Distribution System User
arrangements for Protection at the ownership boundary, including types of apparatus and Plant and
Protection settings, must be compatible with standard practices on the Distribution System, as
specified by MZEC during the process of application for Connection. In particular;
(i) Maximum clearance times (from fault current inception to arc extinction) must be within
the limits established by MZEC in accordance with Protection and apparatus and Plant short
circuit rating policy adopted for the Distribution System;
(ii) In Connecting to the Distribution System the Distribution System User should be aware
that auto-reclosing or sequential switching features may be in use on the Distribution System.
MZEC will on request provide details of the auto-reclosing or sequential switching features in
order that the Distribution System User may take this into account in the design of the
Distribution System User System, including Protection arrangements; and
(iii) The Distribution System User should also be aware that the Protection arrangements on
some Distribution Systems, e.g. rural, may cause disconnection of one phase only of a three
phase Supply for certain types of fault.
1.6.3 Earthing
Earthing of that part of the Distribution System User System that is connected to MZEC’s Distribution
System shall comply with the arrangements specified in DCC.5.2.1.
1.6.4 Fault level considerations
The short circuit rating of Distribution System User’s apparatus and Plant at the Connection Point
should be not less than the design fault level of the Distribution System to which it is connected. The
choice of apparatus and Plant for Connection at Low Voltage may take into account attenuation in
the service lines in accordance with Good industry Practice. MZEC in the design of its System will
take into account the contribution to fault level of the Connected System and apparatus.
In order to permit these assessments to be carried out information should be exchanged on
prospective fault power in feed and X/R ratios, where appropriate, at points of entry to and exit from
the Distribution System.
1.6.5 Capacitive and inductive effects
The Distribution System User shall, when applying to make a Connection, provide MZEC with
information as detailed in DCC.7. Details will be required of capacitor banks and reactors connected
at High Voltage which could affect the Distribution System and which it is proposed to Connect if
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 10
20
18
-
2
02
0
agreed by MZEC. When requested by MZEC details of distributed circuit capacitance and inductance
shall also be provided. Sufficient detail is required to:
(i) Verify that controlling apparatus and Plant of the Distribution System is suitably rated;
(ii) Show that the performance of the Distribution System will not be impaired; and
(iii) Ensure that arc suppression coils when used by MZEC for System Earthing purposes
are correctly installed and operated.
1.6.6 Telemetry
The Distribution System User should provide such voltage, current, Frequency, Active Power and
Reactive Power pulses and outputs and status points from its System as are considered reasonable
by Licensed Distributors to ensure adequate System monitoring. The telemetry outstation in such a
situation will be provided, installed and maintained by MZEC. Under the requirements of the Grid
Code new CDGensets and Production Facilities will need to provide signals to OETC for monitoring
purposes.
If it is agreed between the parties that MZEC shall control the switchgear on the Distribution System
User’s System MZEC shall install the necessary telecontrol outstation. Notwithstanding the above,
it shall be the responsibility of the Distribution System User to provide the necessary control interface
for the Distribution System User switchgear that is to be controlled.
1.7 Requirements for Embedded Gensets
1.7.1 General requirements
Embedded CDGensets shall comply with the general principles of the Grid Code, subject to the
particular requirements of MZEC necessitated by the adjacent Distribution System conditions, which
will be made known by MZEC during the Connection application process. Copies of data supplied in
accordance with the Grid Code shall be given to MZEC.
1.7.2 Provision of information
Embedded Gensets will fall within three basic classes for which the Power Producer shall provide
the following minimum information to MZEC during the process of Connection application or
otherwise as requested by MZEC. When applying for Connection to the Distribution System Power
Producers shall also refer to DCC.5 and OES. The three basic classes are;
a - Embedded CDGensets (All Gensets with a Registered Capacity of 5MW or greater will be
centrally dispatched);
b - Embedded Gensets Connected at or below 20 kV and with an output not in excess of 5MW;
and
c - Embedded Gensets who are to be connected at Low Voltage and less than 300 kVA in
capacity.
MZEC will use the information provided to model the Distribution System and to decide what method
of Connection will need to be employed and the voltage level at which the Connection should be
made. If MZEC reasonably concludes that the nature of the proposed Connection or changes to an
existing Connection requires more detailed consideration then further information may be requested.
It is unlikely that more information than that specified in DCC.8.3.1 will be required for Embedded
Gensets who are to be connected at Low Voltage and are less than 50 KVA in capacity, or connected
at other than Low Voltage and less than 300 kVA in capacity.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 11
20
18
-
2
02
0
1.7.3 Information required from all Embedded Gensets
Each Power Producer will provide to MZEC information on (a) the Gensets and (b) the proposed
interface arrangements between the Genset and the Distribution System. MZEC may require the
following information before entering into an ECA/ECUOSA to connect any Gensets to the
Distribution System:
Genset data
a Terminal volts; kV
b Rated Capacity; kVA
c Rated Capacity; kW
d Maximum Active Power sent out
Reactive Power requirements (if any);
kwso max
kVAr
e Type of Genset; Synchronous, asynchronous, etc
f Type of prime-mover;
g Anticipated operating regime of Gensets; Continuous, intermittent, peak lopping
h Fault level contribution; kA
I Method of voltage control;
j Generator transformer details; As applicable
k Requirements for top-up Supplies and/or standby Supplies;
Interface arrangements
a The means of Synchronization between MZEC and Distribution System User;
b Details of arrangements for Connecting with earth that part of the User System
Connected to the Distribution System;
c The means of Connection and disconnection which are to be employed;
d Precautions to be taken to ensure the continuance of safe conditions should any
earthed neutral point of the User System Operated at HV become disconnected from
earth;
1.7.4 Additional information required from some Embedded Gensets
MZEC may request the information before entering into an ECA/ECUOSA to connect any Gensets
greater in size than 5 MW or connected at a voltage level above 11 kV onto the Distribution System.
1.7.5 Technical requirements
1.7.5.1 Genset performance requirements
For Embedded CDGensets the electrical parameters required would be those detailed in the Grid
Code.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 12
20
18
-
2
02
0
For Gensets not subject to Central Dispatch the electrical parameters that must be achieved at the
Genset terminals are defined according to the Connection method and will be specified by MZEC
with the offer for Connection. Each Genset or Production Facility must be capable of Supplying its
Registered Capacity within the Total System Frequency range 49.50 to 50.50 Hz. The output power
should not be affected by voltage changes within the permitted operating range.
1.7.5.2 Control arrangements
Licensed Distributors will specify in writing if a continuously acting fast response automatic excitation
control System is required to control the Genset voltage without instability over the entire operating
range of the Genset or Production Facility. This will be dependent on the size and type of Genset or
Production Facility and the part of the Distribution System to which it is connected.
1.7.5.3 Coordinating with existing protection
It will be necessary for the Protection associated with Embedded Gensets to co-ordinate with the
Protection associated with the Distribution System as follows:
(i) For Gensets Connected to the Distribution System the Genset must meet the target
clearance times for fault current interchange with the Distribution System in order to reduce
to a minimum the impact on the Distribution System of faults on circuits owned by Power
Producers. MZEC will ensure that MZEC Protection settings meet its own target clearance
times.
The target clearance times are measured from fault current inception to arc extinction and
will be specified by MZEC to meet the requirements of the relevant part of the Distribution
System.
(ii) The settings of any Protection controlling a circuit breaker or the operating values of any
automatic switching device at any Connection Point with the Distribution System shall be
agreed between MZEC and the Distribution System User in writing during the Connection
consultation process.
The Protection settings or operating values shall not be changed without the written
agreement of MZEC.
(iii) It will be necessary for the Genset Protection to co-ordinate with any auto-reclose policy
specified by MZEC.
(iv) Any Genset or Production Facility Connected to the Distribution System will be required
to withstand, without tripping, the negative phase sequence loading incurred during the
clearance of a close-up phase-to-phase fault by System Backup Protection which will be
within the Plant short time rating on the Distribution System. MZEC will advise the Power
Producer of the expected negative phase sequence loadings during the ECA/ECUOSA
process.
1.7.5.4 Islanding
It is possible that a part of a Distribution System to which Embedded Gensets are connected could,
during Emergency Conditions, become detached from the rest of the Distribution System. MZECshall
decide dependent on local network conditions, if it is desirable for the Embedded Gensets to continue
to Generate onto the islanded Distribution System.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 13
20
18
-
2
02
0
If no facilities exist for the subsequent resynchronization of the islanded section of the Distribution
System with the rest of the Distribution System then the Embedded Genset will under Licensed
Distributor instruction, ensure that the Genset is disconnected for resynchronization.
Under Emergency Conditions there is an expectation that some Gensets will continue to operate
outside the Frequency limits set down in the Grid Code CC.6. However, for Embedded Gensets
Connected to the Distribution System at a voltage level less than 33 kV it is likely that this could
mean Connection within an automatic under-frequency Demand disconnection zone. Consequently,
Embedded Gensets should ensure that all Protection on Gensets should have settings to co-ordinate
with those on the automatic under-frequency Demand disconnection apparatus and Plant that will
be detailed by MZEC on request.
1.7.5.5 Black Start capability
Each Embedded Power Producer shall notify MZEC if its Gensets has a restart capability without
Connection to an external power Supply, unless the Embedded Genset shall have previously notified
OETC accordingly under the Grid Code.
1.7.5.6 Genset commissioning tests
Where Gensets require Connection to the Distribution System in advance of the commissioning date,
for the purposes of testing, the Genset must comply with the requirements of the ECA/ECUOSA.
The Power Producer shall prepare a commissioning program and obtain approval to the program
from MZEC to allow commissioning to be coordinated.
2. The 33 kV System
2.1 System Configuration
The 33 kV System of MZEC serves in a distribution role between the OETC and the 11 kV system
as direct 132/11 kV transformation is not in use. The system consists mainly of 33 kV feeders,
33/11kV primary substations and 33/0.415 kV transformers installed on some feeders where it is not
feasible to develop 11 kV network due to limited amount of demand. The 33 kV feeders emanate
from the 132/33 kV grid stations to supply the 33/11 kV primary substations. Primary substations are
of two types, namely indoor type and outdoor type. Indoor primary substations are mainly of 2x10
MVA and 2x20 MVA with 33 kV outdoor/indoor circuit breakers and 14 panels 11 kV indoor
switchgear. Indoor primary substations are proposed to be constructed during the coming years to
supply highly growing areas. Outdoor primary substations are installed throughout the four
governorates of MZEC in urban and rural areas where demand is normally less than 12 MVA. The
normal practice is to supply each primary substation with two 33 kV feeders; each feeder is feeding
one transformer and serves as an alternative supply for the whole substation in case the other feeder
fails. Along the 33 kV feeders, Tees are used to connect primary substations. The whole network is
interconnected especially at South Al Batinah and Al Dakhilyiah governorate except in few situations,
where radial feeders without interconnections with other feeders feed primary substations.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 14
20
18
-
2
02
0
2.2 System Security
The majority of MZEC’s primary substations are of the standard two transformers type with two
separate 33 kV and 11 kV busbars. In some cases where demand is much less than the capacity of
two transformers, which is normal in remote rural areas, primary substations with only one 33/11 kV
transformer are installed. The 33 kV network is designed and will be developed to meet its customer’s
satisfaction and comply with the Distribution System Security Standards (DSSS).
2.3 Selection and Application of Plant
2.3.1 Transformers
Transformers installed in the 33 kV system are categorized into 33/11.5 kV and 33/0.433 kV.
33/11.5 kV transformers are standard as far as the 33 kV system is concerned. The ratings in use
are 1, 3, 6, 10 and 20 MVA. The 1, 3 and 6 MVA transformers are equipped with Off Load Tap
Changers, whereas 10 and 20 MVA transformers are equipped with On Load Tap Changer. All
transformers comply with the requirements of IEC 76/BSS 171. The temperature rise of winding shall
not exceed 50 Deg. C by resistance of oil, 40 Deg. C by thermometer over an ambient of 50 Deg. C.
The 33/0.433 kV transformers are naturally cooled outdoor oil immersed core type and are complying
with the requirements of IEC 76/BSS 171 except that the temperature rise shall not exceed 50 Deg.
C for winding by resistance and 40 Deg. C for oil by thermometer. The smallest rating in use for this
category is 50 kVA and the highest is 1000 kVA.
Currently, the number of 33/11.5 kV substations and transformers exists in the system up to
September 2017 are shown in Table 2.
Table 2: Number of 33/11.5 kV transformers up to September 2017
Asset Type Quantity Total
North Sharqiyah South
Sharqiyah South Al Batinah
Al Dakhilyiah
20MVA 16 24 75 62 177
10MVA 2 9 7 4 22
6MVA 59 40 73 79 251
3MVA 8 0 7 9 24
2.3.2 Switchgear
The 33 kV indoor switchgear is of single bus bar, totally enclosed metal-clad type with withdraw able
circuit breakers or metal-clad SF6 insulated with vacuum or SF6 circuit breakers. 11 kV and 33 kV
current ratings of the bays are shown in Table 3.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 15
20
18
-
2
02
0
Table 3: Current Ratings of Bus Bar, Bus-section, Transformer and Feeder Bays
Rating 11 kV at Primary substations 33 kV
Bus-bar 2000 A 2000A
Bus-Section 1200 A 1200A
Transformer 1200 A 600A
Feeder 400 A 600A
2.3.3 Overhead Lines
Overhead lines are extensively used due to the rural character of MZEC’s Authorized Area. These
are mainly bare ACSR conductors with conductor sizes of 150 mm2 (wolf) or 200 mm2 (panther) on
wooden and concrete poles supported by post insulators. Up to September 2017 the installed
overhead line hit a total of 3880.2 km.
2.3.4 Underground Cables
Due to the rural area character of MZEC’s Authorized Area, 33 kV underground cables are mainly
used to connect overhead lines with grid stations, connecting some overhead lines with primary
substations, road crossings situations and in urban areas and towns where overhead lines cannot
be installed. The standard size commonly in use is the 3-core 300 mm2 copper XLPE cables. It
conforms to relevant IEC specifications. The use of underground cable increases significantly and
the installed length reached around 1269.3 km in October 2017.
2.3.5 Short Circuit Levels
Switchgear installed on the 33 kV Distribution System will be specified with a three-phase
symmetrical short circuit breaking rating not less than 25 kA at 33 kV for 2x20 MVA substations.
2.3.6 Protection
All items of plant will be covered by systems of the main protection. Distance protection is employed
for overhead line feeders.
3. The 11 kV System
3.1 System Configuration
The main purpose of the 11 kV systems is to distribute electricity into and around local urban and
rural areas in an economic, efficient, safe and secure manner whilst meeting the needs of customers.
The general design principle for configuring the distribution system is based on primary substations,
indoor and outdoor with mostly two transformers and 11 kV busbars, providing a continuous firm 11
kV supply. The 11 kV feeders emanate from the 33/11 kV indoor and outdoor primary substations
are mainly overhead lines feeding the distribution transformers. At all indoor primary substations, 11
kV circuit breakers are provided whereas 11 kV Auto-Reclosers are provided at the outdoor primary
substations. Due to the regional character of MZEC’s authorized area, 11 kV underground feeders
are seldom. Interconnections between feeders from the same primary substation or from different
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 16
20
18
-
2
02
0
primary substations through Ring Main Units (RMU), Air Break Switches (ABS) and Open Jumpers
are the normal practice.
These 11 kV feeders are normally operated as radial feeders, with the open point selected for ease
of operational access to minimize customer minutes lost, whilst taking account of the need to meet
security requirements and minimize system losses and voltage drops.
3.2 System Security
In order to meet the customer’s expectations and needs, the 11 kV network is designed and will be
developed to meet the obligations set out in the relevant codes and comply with the approved
Distribution System Security Standards.
3.3 Selection and Application of Plant
3.3.1 Distribution Substations
Distribution substations are of two types, ground-mounted and pole-mounted. For ground-mounted
distribution substations, normally one transformer of rated capacity 500 kVA or higher are used,
whereas those transformers with ratings less than 500 kVA are installed on H-Pole structures. Both
types of substations are fed from the 11 kV feeders either directly with jumpers (Pole-Mounted) or
through 11 kV cables (Ground-Mounted). Expulsion fuses are used to protect both types of
substations on the high voltage side and HRC fuses on the low tension side. However Ground-
mounted transformers connected through HFU are protected by HRC fuses of 63 A and 31.5 A for
1000 kVA & 500 kVA respectively.
MZEC has already started to implement two smaller ratings, namely 25 and 50 kVA to minimize
transformer losses arising from using higher ratings for loads which are far away less than the
capacity of the transformer.
The number of distribution substation exist in the system up to the September 2017 is shown in
Table 4.
Table 4: Number of distribution transformer until September 2017
Governorate Number of Distribution Substation
North Al Sharqiyah 4038
South Al Sharqiyah 2557
Al Dakhilyiah 5175
South Al Batinah 5982
Total 17752
3.3.2 Overhead lines
Overhead lines are extensively used. These are mainly bare ACSR conductors with conductor sizes
of 100 mm2 (dog) or 150 mm2 (wolf) on wooden poles supported by post insulators. MZEC also
introduced SAX insulated conductor in areas suffering from severe climates such as Jalan Bani Bu
Ali and Sur. There is a total of 9495.7 km of 11 kV overhead lines until September 2017 represents
the second highest length of installed circuits in the systems.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 17
20
18
-
2
02
0
3.3.3 Underground Cables
The 11 kV underground cables are mainly used to connect overhead lines with primary substations,
connect some distribution substations with overhead lines, road crossings situations and in urban
areas and towns where overhead lines cannot be installed. The standard sizes commonly in use are
50 mm2, 70 mm2, 120 mm2, 185 mm2and 240 mm2copper XLPE three-core cables. Both conform to
relevant IEC specifications. However, in the planned areas the connections will only be using
underground cables to comply with the Policy of Undergrounding. As stated earlier the increase of
use of underground cable have pushed the total installed 11kV underground cables upward and
reached around 2930.6 km in September 2017 and expected to increase dramatically in the following
years.
3.3.4 Short Circuit Levels
Switchgear installed on the 11 kV Distribution System will be specified with a three-phase
symmetrical short circuit rating not less than 18.4 kA at 11kV.
3.3.5 Protection
All feeders are protected against over-current and earth faults whether emanating from indoor or
outdoor primary substations and distribution transformers are protected with expulsion fuses on the
high voltage side and HRC fuses on the low tension side. In general, the protection will be time
graded and arranged to limit the disruption of supplies in the event of a system fault.
4. The Low Voltage System
4.1 System Configuration
The main purpose of the LV distribution system is to distribute electricity in local urban or rural areas
and to deliver it to customers' LV entry points in an economic, efficient, safe and secure manner.
The LV system will normally be developed as a network of tapered radial mains supplied from a
distribution substation placed near to the load Centre.
4.2 System Security
MZEC’s low tension network is designed and will be developed to meet its customer’s satisfaction
and comply with the approved Distribution System Security Standards.
4.3 Selection and Application of plant
4.3.1 Distribution Substations
The main constituents of the distribution substations are the 11/0.433 kV transformers and feeder
pillars or cutout boxes. The 800A and 1600 A feeder pillars are normally used with Ground Mounted
transformers whereas 400 A control boxes are used for Pole Mounted transformers.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 18
20
18
-
2
02
0
4.3.2 Overhead Lines
Low tension feeders radiate from the distribution substations as insulated overhead lines to supply
the customers by Tees either with overhead lines on 9 meter wooden poles or underground cables.
New main lines are constructed using insulated conductors of cross-sectional area 120 mm2, 185
mm2 and 200 mm2 according to the load although 95 mm2 are still in use. There are around 9920.2
km of installed overhead lines till September 2017 and the increase of this type is expected to slow
down looking to the intensive use of the underground cable.
4.3.3 Underground Cables
Underground cables are used to connect the overhead lines to the distribution substations. They are
also used to connect the premises to the overhead lines. These are of varying sizes such as 1x630
mm2, 4-core 120 mm2, 4-core 150 mm2, 4-core 185 mm2 and 4-core 240 mm2. In new planned areas,
the LT network will be of underground cables only to comply with the Undergrounding Policy. A total
length of 7682.1km of underground cable up to September 2017 is very likely to increase with steep
trend more than the previous years.
4.3.4 Protection
Low tension feeders are protected with HRC fuses at the feeder pillars or cutout boxes.
5. Operating Voltage
The following Table 5 shows MZEC’s operating voltages.
Table 5: MZEC’s operating voltages
Normal System voltage Highest
voltage
Target voltage Allowable
tolerance
415/240 V - 415/240 V ± 𝟔%
11 kV 12.5 kV 11.5 kV ± 𝟔%
33 kV 36 kV 33 kV ± 𝟔%
6. Load Management Areas
During the normal operation of the distribution system, there are no areas of MZEC distribution
network affected by load management scheme. Load management schemes will be employed for
the Demand Control. The need for reduction in Demand arises in situations of insufficient Generation
Capacity and where severe operating difficulties pose a threat to the stability of the Main
Interconnected System including the security of the Distribution System.
7. Other Interconnected Networks
The main interconnection with other networks is with OETC system via grid supply point substations.
These are eight grid substations in South Al Batinah namely Barka Main, Al Sawadi, Muladah, MIS,
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 19
20
18
-
2
02
0
Rustaq, Nakhal, Khdrah and Madinat Barka TX-1 & Tx-2, and eight grid substations in Al Dakhilyiah
namely Nizwa, Madinat Nizwa, Bahla, Izki, Izki-2, Sumail-A, Sumail-B and Adam, three grid
substations in South Al Sharqiyah namely Sur, Jalan BB Ali and Jalan BB Hassan, and three grid
substations in North Al Sharqiyah namely Mudhairib, Ibra and Mudhaibi. Interconnections on the 33
kV and 11 kV voltage level are with Majan Electricity Company and Muscat Electricity Distribution
Company. The 33 kV interconnections with Majan Electricity Company and Muscat Electricity
Distribution Company are mainly alternative supply sources in emergency situations. At some
locations, MZEC has Interconnection with the Ministry of Defence (MOD) which serves mainly for
the import and export of energy which depends on the condition of the demand.
8. The 33 kV System Load Flow Study
8.1 Introduction
A load flow study is necessary to verify that the electrical system has the adequate capacity to supply
the connected load.
In distribution systems, load flow studies are performed to determine the steady-state operation of
the distribution system. A load-flow study calculates the voltage drop on each feeder, the voltage at
each bus, and the power flow in all branch and feeder circuits. Losses in each branch and total
system power losses are also calculated.
Normally, load flow studies determine if system voltages remain within specified limits under various
operating conditions, and whether equipment such as transformers and conductors are overloaded.
Load flow studies are often used to identify the need for additional generation, capacitive, or inductive
VAR support, or the placement of capacitors and/or reactors to maintain system voltages within
specified limits.
Commonly, load flow studies are carried out to investigate:
1) Bus Voltage Profiles
2) Real and Reactive Power Flow
3) Power System Losses
4) Proper Transformer Tap Settings
A load flow study was conducted on MZEC’s 33 kV distribution system.
8.2 Purpose of the Study
This load flow analysis is carried out in accordance with the requirements of Condition 32:
Distribution System Capability Statement of our Distribution and Supply License and the Distribution
Planning Code DPC.4.4 (Three Year Capability Statement). It is intended to study and analyze
MZEC’s 33 kV distribution system from the planning and operation points of view.
8.3 The 33 kV Distribution Network
MZEC’s 33 kV distribution network is composed of four isolated networks:
1) Al Dakhilyiah Distribution Network
2) North Al Sharqiyah Distribution Network
3) South Al Sharqiyah Distribution Network
4) South Al Batinah Distribution Network
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 20
20
18
-
2
02
0
Each of them is fed from the 132/33 kV or 220/33 kV Grid Stations, where 33 kV outgoing feeders
are radiated to feed the 33/11 kV primary indoor and outdoor substations in addition to few pole
mounted 33/0.433 kV transformers.
8.4 The Load Flow Analysis
The starting point of the load flow analysis is the existing 33 kV networks of the four governorates in
summer 2017. Using ETAP software, load flow for the Loading Category Summer 2017 was
conducted, using the measured loads of summer 2017, for the four governorates, Al Dakhilyiah, Al
Sharqiyah (South and North) and South Al Batinah separately. In this study, the measured 11 kV
currents which were measured in the 11 kV feeders of substations were used to carry out this study.
As the purpose of the present load flow analysis is to assist preparing MZEC’s Capability Statement
for the period 2018-2020, the measured loads were used as the basis for the studies in 2018, 2019
and 2020. The results of each study phase (Loading Category) were analyzed in relation to
equipment’s loading and voltage magnitudes at the 33 kV and 11 kV buses. Equipment with
overloading and bus bars with under voltages were identified. The network reinforcement required
to relief the overloaded equipment and improve the voltage profiles are proposed and the networks
of the four governorates are modified accordingly and a new load flow study is conducted.
Complete and Summary reports for each region are available on request.
8.5 Presentation of Results and Single Line Diagrams for the Years 2018-2020
For simplicity and ease of understanding, the results of the load flow analysis are regenerated in MS
Excel spread sheets in the annexure listed below.
1) Annexure 1-A-1: Al Dakhilyiah Equipment Loading (Primary Substations)
2) Annexure 1-A-2: Al Dakhilyiah Equipment Loading (33 kV Feeders)
3) Annexure 1-B-1: South Al Sharqiyah Equipment Loading (Primary Substations)
4) Annexure 1-B-2: South Sharqiyah Equipment Loading (33 kV Feeders)
5) Annexure 1-C-1: South Al Batinah Equipment Loading (Primary Substations)
6) Annexure 1-C-2: South Al Batinah Equipment Loading (33 kV Feeders)
7) Annexure 1-D-1: North Al Sharqiyah Equipment Loading (Primary Substations)
8) Annexure 1-D-2: North Al Sharqiyah Equipment Loading (33 kV Feeders)
The single line diagrams for the years 2018, 2019 and 2020 are available on request.
9. The 33 kV Short Circuit Analysis
It is normally understood by the short-circuit calculation, the calculation of the characteristic short-
circuit quantities. Namely, Initial Symmetrical Current, Peak Current, Breaking Current and the
Steady State Current. These currents can produce considerable thermal and mechanical stresses
in electrical distribution equipment. The faults causing these current interrupt the system’s steady-
state operating condition and may lead to instability, loss of synchronism and outages. Their
calculation is a perquisite in system design, planning and operation to ensure that the system
components are properly selected to withstand these abnormal currents and the protective devices
are capable to detect and interrupt them. Proper interruption of these currents will protect the
personnel, public, animals as well as the equipment.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 21
20
18
-
2
02
0
The Short Circuit Study is conducted on Mazoon’s 33 kV distribution network as part of its Three
Year Capability Statement in accordance with the requirements of Condition 32 of MZEC Distribution
and Supply License. The short circuit study is carried out on the Mazoon’s three 33 kV networks for
the years 2018 - 2020 using ETAP. In the study, only load connected buses are short circuited i.e.
33 and 11 kV busbars excluding nodes.
The results showed that all the short circuit currents are below the equipment rating in all
governorate.
For simplicity, only the 3- Fault Currents for the years 2018, 2019 and 2020 are shown. These are
presented in Annexure 2-A-1, 2 & 3, 2-B-1, 2 & 3, 2-C-1, 2 & 3 and 2-D-1, 2 & 3 for the four
governorates Al Dakhilyiah, South Al Sharqiyah, South Al Batinah and North Al Sharqiyah
respectively.
10. Voltages Non Compliance
Non-compliance towards the voltage standards is presented for the 33 kV busbars at the primary
substations only. The voltage non-compliance observed at the 33 kV busbars is not affecting the
voltage at the 11 kV busbars, due to the existence of the tap changers. Due to the fact that the
majority of MZEC customers are connected at the LV network, there is no clear and reliable
information on the number of voltage non-compliances at the customer premises. However, MZEC
keeps records of customer complaints and take them into consideration while carrying out the
reinforcement programs. The partial incorporation of 11kV modeling into the upcoming Capability
Statements will provide a better picture on the status of voltage at the customer side. Having said all
of the above, it is worth mentioning that at peak hours the voltage at the grid substations falls beyond
the normal operating value. The voltage non-compliances are shown in Annexure VD-A-1, 2 & 3,
VD-B-1, 2 & 3, VD-C-1, 2 & 3 and VD-D-1, 2 & 3 for the four governorates Al Dakhilyiah, South Al
Sharqiyah, South Al Batinah and North Al Sharqiyah governorates respectively for period 2018 -
2020. However, we are maintaining the voltage level at 11 kV through the capacitors and
Transformer tap changer, so that the voltage with distribution user are maintained within ±6%.The
proposed reinforcement projects will relief the distribution system components and consequently,
the voltages at the non-compliant buses will be improved.
The additional capacitive capacity will bring the power factor at the primary level within the range of
(0.95 lagging to 0.95 leading) specified in the Distribution Code and Grid Code and help keeping the
voltage within ± 6% . Furthermore, the reduction of the reactive current flowing in the 33 kV network
for long distance will reduce the distribution losses.
11. Distribution System Security Standards (DSSS)
After the approval of Distribution System Security Standards in November 2008 as shown in Table
6 below, MZEC is obliged to comply with the Planning requirements of Security Standards. Since
the grant of MZEC’s Distribution and Supply License, MZEC has started planning its distribution
network to comply with simple planning principle to supply its customers with a high quality product.
The starting point was the purchase of high quality power system analysis software, namely
Electrical Transient Analysis Program (ETAP), for the analysis of its distribution system. The 33 kV
networks of the four governorates namely Al Dakhiliyah, Al Sharqiyah (South and North) and South
Al Batinah were drawn in the ETAP as early as 2006 and MZEC presented its first Three Year
Capability Statement with the aid of this powerful software. The results obtained from the ETAP
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 22
20
18
-
2
02
0
encouraged MZEC to purchase another three Licensees for its 11 kV networks and also upgraded
the original version.
Table 6: Distribution System Security Standards
DEMAND CLASS Initial System Conditions
First Outage
(Forced Outage)
Second Outage
(Planned Outage + Forced
Outage)
A Less than 2 MW Repair time No requirement
B 2 to 6 MW 3 Hours No requirement
C 6 to 20 MW Within 15 minutes Restoration time of planned outage
D 20 to 100 MW Immediately Restoration time of planned outage
E Greater than 100 MW Immediately Immediately, 2/3rds of demand
The load flow study carried out on the 33 kV networks of the four governorate showed compliances
and non-compliances towards Distribution System Security Standards for the 33 kV feeders and the
33/11 kV substations. The study is based on the measured currents of the 33/11 kV substations in
summer 2017 for the load category 2017. The results of the study for the three years 2018-2020
were analyzed against the security standards for the feeders and the substations for each
governorate separately. The 33 kV feeders and 33/11 kV substations that are not complying with the
Distribution System Security Standards (DSSS) are presented in a tabulated form of prospective
security derogation lists.
According to the Security Class, a 33 kV feeder is considered not complying with the standards if,
upon a fault on the feeder the Demand Group cannot be supplied within the prescribed period of
time. Where a portion of the feeder cannot be fed back, the feeder is considered and classified as
non-compliant. For the 33/11 kV substations, two situations are of interest. In the first case, if two
transformers are installed in a substation but the total load is greater than the capacity of one
transformer, then the substation is considered non-compliant. The second situation is where only
one transformer is installed and there is no link to a nearby substation that can take the affected
demand group, then the substation is considered non-compliant. It is worth mentioning that the non-
compliance is only during the summer period. For most of the year many feeders and substations
are compliant with the DSSS except the radial feeders, T-Offs and substations with only one installed
transformer. All investments in MZEC Network are to make all substations compliance with DSSS.
12. Demand Forecast
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 23
20
18
-
2
02
0
12.1 Introduction
MZEC’s annual peak demand forecast is the essential first value of input into development plans.
Annual peak demand is the highest rate of energy demand across the course of a year. By monitoring
and planning for peak demand, MZEC ensures the distribution networks maintain the ability to
provide a reliable supply under the most strenuous load demand conditions. MZEC is monitoring
and reviewing the peak demand annually to ensure:
Identify the change of load trends.
Looking for the impact of increasing load to the customer especially Industrial and
commercial.
Development of the efficient network expansion plans to match the demand forecast and
support economic development.
Observation of annual peak load ensures the most recent information and country development are
considered when forecasting the expected impact on each individual substations and the total
system peak for the main interconnected system. For each substation, separate measure are used
to determine the substation peak load and the substation load at the time of the total system peak
load as each of these peak loads may not occur at the same time or have the same drive. Moreover,
the detailed geographical level of substation allow distribution planning to identify demand growth in
the area.
MZEC is one of the areas rapidly developing in Oman. Because the government provides the basic
infrastructure in this areas, so the people are encouraged to invest and build in MZEC areas
especially in South Al Batinah Governorate which is the most densely populated governorate in the
Sultanate. Next table shows the percent growth from 2008 until 2017. It’s obviously the percent of
growth increased rapidly in 2011 and 2012 and the sharp drop in load growth in 2010 was due to
adverse weather conditions.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 24
20
18
-
2
02
0
Figure 1: MZEC peak load
The average growth as be seen in above figure is approximately 7.2% for all MZEC area. It’s
expected to increase the load for upcoming years. Because MZEC recognized non ordinary growth
driven by considerable number of governmental investments in form of tourism projects,
infrastructure projects, and industrial projects as well as private sector investments accompanying
them.
12.2 Load Curves
To give a general view of the load behavior, the load profiles for MZEC taken at Sunday 25th June
2017 which is the day of MZEC Peak was plotted and presented in Figure 2 below. The highest load
was reached at 15:00 hours due to in this hour most of the people returned to their houses to take
rest after duty time, in this day the load recorded was 2120 MW.
Figure 2: The Load Profile of MZEC
0
9.7
2.4
11.311.1
5.2
8.2
12.5
4.9
6.8
0
2
4
6
8
10
12
14
0
500
1000
1500
2000
2500
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
MZEC Peak Load MW & %Growth
Peak load MW % Growth
0
400
800
1200
1600
2000
2400
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
MW
Hours
Daily Load Carve
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 25
20
18
-
2
02
0
Similarly, a weekly load profile covering the period from 22th June to 28th June 2017 was plotted in
Figure 3 to show the load behavior of MZEC load in a typical week of the year. The selected week
included MZEC peak day. It is obvious that the load during weekend slightly less than that during
normal days.
Figure 3: Weekly Load Profile
To complete the picture, the yearly load profile for year 2017 until October was also plotted in
Figure 4. The yearly load profile was obtained from plotting the highest reading in each month to
from the Maximum load profile for the entire MZEC System as well as for each governorate.
Figure 4: MZEC Yearly Load Profile 2016 (Jan-Oct)
0200400600800
10001200140016001800200022002400
Thursday Friday Saturday Sunday Monday Tuesday Wednesday
MW
Weekly Load Profile (22 June - 28 June 2017)
Max Load MW Min Load MW
0
500
1000
1500
2000
2500
MW
Months
MZEC Max Load MW Dakhiliyah Max Load MW
North Sharqiyah Max Load MW South Batinah Max Load MW
South Sharqiyah Max Load MW
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 26
20
18
-
2
02
0
Mazoon Load curve follows a typical load behavior in hot countries as the peak period is in summer
season that starts approximately in April and ends in September. It can be also of importance to
notice that MZEC Peak is almost three times its minimum load recorded in off peak period during
January and February. The demand side management need to consider this issue to minimize the
gap between peak period and off peak period which no doubt will result on savings at generation,
transmission and distribution systems.
As can be seen from the graph of Figure 4, that South Al Batinah Load represent the highest load
among the all the governorates followed by Al Dakhilyiah and Al Sharqiyah (South + North)
governorate.
12.3 Demand forecast Methodology
This section covers the forecast methodology and the results of MZEC’s forecast of energy demand
expressed in Regulated Units Distributed (RUD) and customer accounts (CA) for 2018 – 2022. The
demand forecast is a fundamental driver of the subsequent forecasting of Price Control 5 (PCR5).
Crucially the forecast makes a distinction between autonomous demand growth and that due to
corporate projects.
Autonomous demand growth: driven by the year-on-year increase in the number of customer
accounts and in the regulated units distributed which are derived from the increase in the population
within the MZEC service area and GDP per capita. Even with uncertainty and statistical errors that
occur in the source data, it is reasonable to suppose that both drivers will grow at a fairly predictable
rate that reflects the immediate past history of its actual growth.
Corporate projects: Customer accounts and especially distributed energy will also increase as a
consequence of significant, large-scale developments referred to as corporate projects. The timing
and impact of the corporate projects on MZEC’s network is difficult to predict as such projects
constitute a variety of national initiatives influenced by national and international factors, developers’
priorities and timescales, and other factors outside of MZEC’s control and reasonable forecasting
practices. Corporate projects at completion typically add a one-off increase in the number of
customer accounts (large or small, according to their nature) and in the units distributed (which may
then have its own annual growth rate as the development matures). MZEC bases its forecast of the
impact of corporate projects on a mix of historical trends, current developments, and communication
with developers and the government.
Autonomous Demand Growth
The forecast of autonomous demand growth is based on an econometric model developed for the
Price Control 5 (PCR5) submission, using the latest available data on population growth and
economic (GDP per capita) growth in Oman. Both factors are key drivers for the increase in customer
accounts as well as the average energy consumed per customer account. International studies show
a significant positive correlation between GDP per capita and average energy consumption per
capita. As the GDP per capita of a country rises, private households are able to afford more electrical
appliances, and industrial and commercial enterprises replace labor with capital. The link between
population growth and the number of customer accounts is self-evident. MZEC’s confidence in the
robustness of this econometric model has been reinforced by the good agreement between its
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 27
20
18
-
2
02
0
forecasts made for PCR5 and the actual outturn in number of customer accounts and units
distributed in 2011 to 2015.
The input data used in the forecast is as follows:
1. Population data for the area served by MZEC has been taken from data published by the
Oman Information and Statistics Center1; and
2. Data and projections on Oman GDP economic development are taken from data published
by the International Monetary Fund in its World Economic Outlook Database2.
Corporate Projects/Customers
MZEC classifies as Corporate Projects those developments known to MZEC as of December 2016,
where the developers or prospective customers have indicated their intention to connect substantial
new loads to the MZEC network. These have an effect on the load expected to be distributed in the
period of the PCR5 price control, of a magnitude and incidence that is difficult to anticipate,
dependent as it is upon the independent decisions of developers and major customers which are in
turn subject to a variety of factors.
The additional number of customer accounts involved in these projects can be quite small, but the
increase in energy consumed can be very substantial with a significant impact on the total energy
distributed to these categories, e.g. the Industrial, Tourism, and Ministry of Defense (MoD) sectors.
For these three categories, MZEC may reasonably assume – absent any indications to the contrary
– that existing demand (as of end-2016) will not exhibit significant autonomous growth (existing
tourist facilities will maintain their occupancy level – and hence energy consumption, as will MoD
facilities; existing industrial plants will operate at the current level of production). The volume and
timing of demand growth in the Tourism and Industry categories depends on national and
international economic developments as well as decisions by individual investors. MoD expansion
of new facilities is mostly driven by political decisions internal to Oman. MZEC is therefore only able
to forecast demand growth due to those industrial, tourism or MoD projects known to MZEC as of
December 2014, that are expected to be connected during the PCR5 price control period. Other
corporate projects known to MZEC are in the Residential (such as the South Al Batinah Coastal Area
Residences), Commercial and Government categories. Whilst not negligible, these projects will add
a relatively small increase to the number of customer accounts and units distributed in these already
very large customer categories.
The number of all such projects, their incidence and nominated peak demand expected in the
Capability Statement 2017-2019 period are:
1http://www.ncsi.gov.om/NCSI_website/viewPublication.aspx?id=1958, published Jan 2014
2https://www.imf.org/external/datamapper/index.php, published Jan 2014
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 28
20
18
-
2
02
0
Table 7: Peak Demand in MW of Corporate Projects by Customer Category expected in 2018-2020
Customer category
Number of projects
Peak Demand (MW)
2018 2019 2020
Residential 0 0 0 0
Government 19 61 66 82
Commercial 7 18.8 21 31
Industrial 4 60 65 89
Agriculture 1 3.2 3.2 3.2
Tourism 1 17.6 17.6 17.6
MOD (Defense) 3 15.8 22.6 22.6
Our forecast of the number of customer accounts and the units distributed under these corporate
projects is based on the prospective connection data made available to MZEC by the project
developers. Using their project timetable and their nominated MW capacity or peak demand, the
MZEC Planning Department:
1. Reviews and analyses, discuss and validate the requests with the developers to arrive at
reasonable values of total connected load; and
2. Estimates their coincident after diversity and load factor (CADLF) energy consumption using
diversity and load factors determined from comparable historic data in the MZEC area and
from corresponding data in comparable countries.
Whilst MZEC recognizes the inherent uncertainty introduced to the demand forecast by basing
special project figures on the developers’ own proposed timetable and capacity requirements, MZEC
is reasonably confident that adding these estimates to the values produced by our econometric
model introduces a negligible error to the forecast of customer accounts and energy distributed in
the PCR5 price control period.
Table 8: MZEC coincident after diversity and load factor Tariff category
Residential Government Commercial Industrial Agriculture
Coincident Factor 60% 40% 60% 80% 30%
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 29
20
18
-
2
02
0
13. Future System Development Projects
From the load flow study carried out on Mazoon’s 33 kV network, loaded and overloaded equipment
together with bus bars suffering under voltage conditions are identified. Necessary measures
required to relief the equipment and improve the voltage, are presented in a form of three strategic
development statements explaining the changes will be experienced by each Governorate.
Annexure (1-A-1, 1-A-2, 1-B-1, 1-B-2, 1-C-1 and 1-C-2) that illustrate the loading and the status of
compliance with the DSSS and presents the effect of these measures up to the end of this capability
statement which is year 2020. The fifth Price Control 2018-2021 aims to improve the situation of the
compliance with DSSS in primary substations and 33 kV feeders gradually. In addition, MZEC has
prepared a plan for the new investments required in 2018 to reinforce the 33 kV network and to
ensure the compliance with the security standards. Many of substations and feeders will start moving
towards the compliance situation. However, there are many other substations and feeders need
more investments to be complied. As MZEC is experiencing a round two digit growth annually, it is
challenging to plan and deliver all the required investments to cater for the load growth and comply
as much as possible with the Security standards requirement taking into consideration the
increasingly developing internal and external capabilities. MZEC has taken various steps to tackle
any bottlenecks in the project management cycle and with these interventions our capabilities to
deliver all the required capital expenditure will no doubt improve.
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 30
20
18
-
2
02
0
Table 9: 33 KV Projects for Al Dakhilyiah 2018-2020
No. PIAD No. Project Name District Expected
completion Year Project Status Target
1 DH 04/2013Upgrading of Kamah Substation to 2x20 MVA with one
new 33 kV feedersNizwa 2018 Commissioning Stage
To enhance the compliance to
the security standards
2 DH 1/2012Upgrading of Hay Al Ain to 3x6 MVA with two new 33
kV feedersNizwa 2018 Commissioning Stage
To enhance the compliance to
the security standards
3 DH 08/2013 Construction of new 2x20 MVA Al Mamorah substation Bahla 2018 Commissioning StageTo relive load from Bahla Grid
Substation
4 DH 09/2012 Construction of New Jibreen Grid Bahla 2018 Commissioning Stage To relive load from Bahla Grid
5 DH 07/2013 Al Zoubar 2x20 MVA with 2 new 33 kV feeders Adam 2018 Commissioning StageTo relive load from Adam Grid
Substation
6 DH 08/2013 Upgrading Timsa substation to 2x20 MVA Nizwa 2018 Commissioning StageTo enhance the compliance to
the security standards
7 DH 01/2012 New 33 kV feeder from Madinat Nizwa to Hay Al Ain Nizwa 2018 Commissioning Stage To supply Hay Al Ain Tx-3
8
Due to
Complex
Connection
Upgrading Mitan to 2x6 MVA Adam 2018 Commissioning StageTo enhance the compliance to
the security standards
9 DH 05/2013Construction of New Qalat Al wamer (Izki-2) Grid with
3 new 33kV feedersIzki 2018 Commissioning Stage To relive load from Izki Grid
10 DH 02/2013New 2x20 MVA substation is proposed to be
constructed in Jebel Al Akhder areaIzki 2018 Commissioning Stage
To meet high growth in the area
and relive some load from Jebel
Al Akhder 2x6 MVA .
11 DH 05/2013 Upgrading Al Aqil substation from 1x6 MVA to 2x6 MVA Izki 2018 Commissioning StageTo enhance the compliance to
the security standards
12 DH 05/2013
Upgrading Somrah substation from 2x6 MVA to 3x6
MVA and Wadi Mahram substation from 1x6 MVA to
2x6 MVA
Izki 2018 Commissioning StageTo enhance the compliance to
the security standards
13 DH 06/2012Construction of Sumail Industrial Zone-1 3x20 MVA
substation with two new 33 kV feedersSumail 2018 Commissioning Stage To meet high growth in the area.
14 DH 06/2012Construction of Sumail Industrial Zone-2 2x20 MVA
substation with two new 33 kV branchesSumail 2018 Commissioning Stage To meet high growth in the area.
15 DH 05/2012 Upgrade AL Hamim to 3x6 MVA Sumail 2018 Commissioning StageTo enhance the compliance to
the security standards
18 DH 05/2012Construction of Saih Al-Moaideen 2x20 MVA
substation with two new 33 kV branches Sumail 2018 Commissioning Stage
To meet high growth in the area
and relive some load from
BidBid Substation and Multqa
Substation .
20 DH 02/2013
Constrcution of 33kV Double Circuit Towers Lines
From Izki Grid to New Jabal AL Akhdher Primary
Substation
Nizwa 2019 Designing StageTo supply New Jabal AL
Akhdher 2x20 MVA
21 DH 05/2013Upgrading Qalat AL Awamer substation from 2x6 MVA
to 2x20 MVA with 2 new 33 kV feeder from Izki-2 Grid.Izki 2019 Execution stage
To enhance the compliance to
the security standards
22 DH 05/2013
Construction of Al-Hamim 33 kV feeder from Sumail
Grid to Bidbid 2x6 MVA, Fanja Water Pump and MOD
Bidbid
Sumail 2019 Designing StageTo relive load from Fanja-1 and
Fanja-2 33 kV feeders
23 DH 05/2013Extend existing Al Aqil 33 kV feeder into Humaidha
S/S with auto changeover. Izki 2019 Designing Stage To supply Humaidha Tx-3
24 DH 05/2013Upgrading Humaida substation from 2x6 MVA to 3x6
MVAIzki 2019 Execution stage To meet high growth in the area.
25 DH 05/2013
Construction of 2x6MVA PSS (Al Sayma)with 33KV
feeder from existing Feeders and 11KV feeders at Izki
in Al Dakhiliyah Governorate
Izki 2019 Designing Stage
To meet high growth in the area
and relieve load from Sayma
Temp. Substation.
26 DH 09/2012Construction of a new 3x20 MVA substation in Al
Hamra.Bahla 2019 Execution stage
To meet high growth in the area
and relive load from Al Hamra
Substation.
27 DH 07/2013 Upgrade Adam Grid from 2x63 MVA to 2x125 MVA Adam 2019 Designing StageTo enhance the compliance to
the security standards
28 DH 08/2013Construction new Grid in Birat Al Mouz with capacity
of 2x125Nizwa 2020 Designing Stage To relive load from Izki Grid
29 DH 08/2013Construction of new 2x20 MVA Hay Al Turath
substationNizwa 2020 Designing Stage
To meet high growth in the area
and relive some load from
Nizwa Stadium Substation and
Farq Substation .
30 DH 08/2013Upgrading Izz substation from 1x6 MVA to 2x10 MVA
indoor substationNizwa 2020 Designing Stage
To enhance the compliance to
the security standards
31 DH 09/2012Upgrading Al Habi substation from 2x10 MVA to 2x20
MVABahla 2020 Designing Stage
To enhance the compliance to
the security standards
32 DH 07/2013Construction new Jibreen 2x20 MVA primary
substationBahla 2020 Designing Stage
To meet high growth in the area
and relieve load from Jibreen
Substation.
33 DH 05/2013Construction new 2x20 MVA substation called Al
Afiyah with one new 33 kV feeder from Izki GridIzki 2020 Designing Stage
To meet high growth in the area
and relieve load from Al Afiyah
Temp. Substation.
34 DH 06/2012 Construct Sumail Industrial grid with 33 kV switchgear Sumail 2020 Designing StageTo relive load from New Sumail
Grid
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 31
20
18
-
2
02
0
Table 10: 33 KV Projects for South Al Sharqyiah 2018-2020
No. PIAD No. Project Name District Expected
Completion Year Project Status Target
1
SH-02/2012
Upgrading Al Kamil primary substation from 2x20
MVA to 3x20 MVA with constructing 33 kV branch
between Al Kamil primary substation and Al Kamil
Water Pump
Jalan BB Hassan 2018 Commissioning Stage
To comply with DSSS and
relieving the load from existing
primary substation
2
SH 01/2012Construction of a new 3 x 20 MVA primary substation
Jalan Bani Bu Hassan-2Jalan BB Hassan 2018 Execution stage
Relieve the load from existing
JBB Hassan primary substation
3 SSH 03/2016 Upgrade Al Ashkharah primary substation to 2x20
MVAJalan BB Ali 2018 Designing Stage
To comply with DSSS and
relieving the load from existing
primary substation
4 CC/08/2016New 33 kV feeder from Sur Grid to Al Jinah 2x10 MVA
SubstationSur 2019 Commissioning Stage
To secure the 33kV supply to
ROP Headquarter, Sur ROP
and Al Jenah primary
substations
5 SH 01/2012Upgrading Stadium substation from 2x6 MVA to 2x20
MVA with new 33kV branchSur 2020 Designing Stage
To comply with DSSS and
relieving the load from existing
primary substation
6 SH 01/2012
Construction of a new Al Egga Grid 2 x 20 MVA
primary substation with two dedicated feeders from
Al-Egga Grid
Sur 2020 Designing Stage
Relieve the load from existing
Sur Town and Al Shariyah
primary substations
7 SH 01/2013Construction of Al Musfiyah 3 x 20 MVA primary
substation with three dedicated feeders from Sur GridSur 2020 Designing Stage
Relieve the load from existing Al
Egga and Shiya primary
substations
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 32
20
18
-
2
02
0
Table 11: 33 KV Projects for South Al Batinah 2018-2020
No. PIAD No. Project Name District Expected
completion Year Project Status Target
1 SB-35/2012 Construction of 33 kV switchgear of Khadra -B Grid Suwaiq 2018 Execution stage To releif load from MIS Grid
2
SB-01/2012 Upgrading Bidaya from 2x20 MVA to 3x20 MVA Suwaiq 2018 Execution stage
To meet high growth in the area
and relieve some load from
Bidaya suq 2x6 MVA and Shabyah
2x6 MVA.
3
SB-04/2013
Construction of AL Batha 3x20 MVA substation with
three feeders link with existing (Khadhra-1, Khadhra-2 &
Marbal Factory) feeders MIS grid.
Suwaiq 2018 Commissioning Stage
To relieve loads from Suwaiq, AL
Hatheeb and Suwaiq I Area
Substations
4SB-22/2012
Upgrade Wadi AL Jahawer to 2x6 MVA and Al Haimly to
2X6 MVASuwaiq 2018 Execution stage
To enhance the compliance to the
security standards
5
SB-01/2012Construction of Badi Al Amod 3x20 MVA substation with
new two feeders.Suwaiq 2018 Execution stage
To be ensure compliance of
security standards of Bidaya
substation
6SB-01/2012
Upgrading od Dhyan 2x20 MVA substation with new two
feedersSuwaiq 2018 Execution stage
To enhance the compliance to the
security standards
7
SB-02/2013Construction Al Uraiq 3x20 MVA substation with three 33
kV feeders from Khadra gridSuwaiq 2018 Execution stage
To relieve loads from Khahra,
Khadra Bu Rshaid and Al Uqdah
Temp
8SB-35/2012
Construction two new feeder to Marble Factory 3x6 MVA
substationSuwaiq 2018 Execution stage To relieve load from MIS Grid
9SB-35/2012
Construction of two new feeders to Khadhra Bu Reshaid
2x20 MVA substation Suwaiq 2018 Execution stage To relieve load from MIS Grid
10 SB-35/2012 Construction of new 33 kV feeder to Bidaya Tx-3. Suwaiq 2018 Execution stage To supply Bidaya Tx-3
11SB-04/2013
Construction of Suwaiq Grid 33 kV busbar and 33 kV
switchgear with nine 33kV feedersSuwaiq 2018 Execution stage To relieve load from MIS Grid
12Coastal Area PIAD
Construction of Musanah Al Sahil 3x20 MVA substation
with three feeders from Blue City GridMusnah 2018 Commissioning Stage
To relieve load from Musansh
Substation
13SB-05/2013 Upgrading Maharh from 2x20 MVA to 3x20 MVA. Musnah 2018 Execution stage
To enhance the compliance to the
security standards
14SB-05/2013 Upgrading Muladah from 2x20 MVA to 3x20 MVA Musnah 2018 Execution stage
To enhance the compliance to the
security standards
15SB-05/2013
Construction of Muladah-B Grid 33 kV busbar and 33 kV
switchgear with five 33kV feedersMusnah 2018 Commissioning Stage
To relieve load from Mulladah
Grid
16SB-05/2013 Constructing Maghser South 2x6 MVA Substation Musnah 2018 Execution stage
To relieve loads from Maghser
South Temp. Substation
17SB-05/2013
Upgrading Musanah Industrial from 1x3 MVA to 2x20
MVA Substation Musnah 2018 Execution stage
To enhance the compliance to the
security standards
18SB-08/2013
Upgrading of Wadi Bani Awf substation from 1x6 MVA to
2x20 MVARustaq 2018 Execution stage
To enhance the compliance to the
security standards
19SB-07/2013 Construction of 33 kV switchgear of Madinat Barka-B Grid Barka 2018 Execution stage
To relive load from Madindt Barka
-A Grid.
20SB-07/2013
Upgrading of Barka Town substation from (2x 20 MVA) to
(3 x 20 MVA) with a 33kV feeder from Madinat Barka GridBarka 2018 Commissioning Stage
To enhance the compliance to the
security standards
21SB-07/2013
Construct of Saqsuq-1, Saqsuq-2 and Saqsuq-3 to relive
load from Madinat Barka-BBarka 2018 Execution stage
To relieve load from Madinat
Barka _A Grid.
22 CC/04/2015 Construction of 33 kV switchgear of Hai Asem Grid Barka 2018 Commissioning Stage
23
SB-07/2013
Constructing of Al Huradi substation with a capacity of
3x20 MVA and three new 33 kV feeders from Madinat
Barka Grid-B
Barka 2019 Designing StageTo relieve load from Somahan
and Barka New substations
24
SB-07/2013
Constructing of Somahan South substation with a
capacity of 2x20 MVA and two new 33 kV feeders from
Madinat Barka Grid-B
Barka 2019 Designing Stage
To relieve load from Barka Town
substation, Somahan and
Somahan South Temp
25SB-07/2013
Constructing Al Haram 3x20MVA substation with three
33kV feeders from Hai Asem Grid.Barka 2019 Designing Stage
To relieve load from Rumais and
Salaha substations
26SB-07/2013
Upgrading of Al Uqair substation to 2x20 MVA with a new
33kV feeder tapping from Barka-5 feeder. Barka 2019 Designing Stage
To be complying with DSSS
requirements
27SB-09/2013
Construct a new Wadi Al Sahtan 1x6 MVA substation in 4
km away from Wadi Al Sahtan 2x6 substationRustaq 2019 Designing Stage
To relive the substation and to
improve the voltage in this area
28
SB-09/2013Upgrading of Wadi Bani Ghafer from 2x6 MVA to 2x20
MVA with 2 new 33 kV feeders from Wadi Bani Awf GridRustaq 2019 Execution stage
To enhance the compliance to the
security standards
29SB-09/2013
Upgrading of Al Hazim substation from (2x 6 MVA) to (2 x
20 MVA) Indoor substation. Rustaq 2019 Execution stage
To be complying with DSSS
requirements
30SB-09/2013
Upgrading of Awabi substation from 3x6 MVA to 2x20
MVARustaq 2019 Execution stage
To comply with DSSS
requirements
31SB-09/2013 Construction of new 2x6 MVA substation in Al Marji area Rustaq 2019 Designing Stage To relive Al Kahaf substation
32
SB-09/2013Constructing of Kasfah 2x20 MVA substation with two
33kV feedersRustaq 2019 Execution stage
To relive load of existing Woshil
2x20 MVA, Rustaq 2x20 MVA and
Makhsoufah 2x6MVA substation
33SB-08/2013
Construction of New feeder from Rustaq Grid to Wadi
Bani AwfRustaq 2019 Designing Stage To secure the 33kV supply
34New Upgriding Twayah from 1x6 MVA to 2x6 MVA Substation Nakhal 2019 Designing Stage
To be complying with DSSS
requirements
35SB-08/2013 Construction of Al Hajir 1x6 MVA Substation Rustaq 2019 Designing Stage
To relieve loads from Al Haimly
Substation
36SB-09/2013
Constructing of New Woshil 2x20 MVA substation with
two 33kV feeders from Rustaq Grid Rustaq 2020 Designing Stage
To relive load of existing Woshil
2x20 MVA substation
37
SB-07/2013Constructing Hai Asem 3x20MVA substation with three
33kV feeders from Hai Asem GridBarka 2020 Designing Stage
To relieve load from Salaha
substation and Al Haram Temp
substation
38
SB-07/2013 Construction of Felaij 2x20 MVA Substation Barka 2020 Designing Stage
To relieve Load from Felaij
Village, Felaij Temp and Halban
substation
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 33
20
18
-
2
02
0
Table 12: 33 KV Projects for North Al Sharqyiah 2018-2020
No. PIAD No. Project Name District Expected
Completion Year Project Status Target
1
SH 05/2012Construction of new Sinaw-B 2 x 20 MVA primary
substationMudhaibi 2018 Commissioning Stage
Relieve the load from existing
Sinaw primary substation
2
SH 02/2013Sinaw 132/33 kV grid station 2x125 MVA with 33 kV
outgoing feeders Mudhaibi 2018 Execution stage
Relieve the load from existing
Mudhaibi grid station
3 SH 03/2013
Construction of new Yahmadi substation 2x20 MVA
and construction of two new 33 kV feeders from Ibra
Grid
Ibra 2018 Execution stageRelieve the load from existing
Yahmadi primary station
4 SH 03/2013Construction tow 33 kV feeders from Ibra Grid 2x125
MVA link with existing 33 kV Dima & Tayeen feeders.Wadi Tayeen 2018 Execution stage
To solve the voltage issue at
Wadi Tayeen area
5 SH 04/2013Upgrading Ghayadah substation from 2 x 6 MVA to 3
x 6 MVAWadi Tayeen 2018 Commissioning Stage
To comply with DSSS and
relieving the load from existing
primary substation
6 SH 06/2013
Upgrading Wadi B Khalid substation from 2 x 6 MVA
to 3 x 6 MVA, Lawrange substation from 1 x 6 MVA to
2 x 6 MVA and Hiyal substation from 1 x 6 MVA to 2 x
6 MVA
Bidayah 2018 Commissioning Stage
To comply with DSSS and
relieving the load from existing
primary substations
7 SH 06/2013Construction of New Shariq Primary 2x 20 MVA
substationBidayah 2018 Execution stage
Relieve the load from existing
Mintrib and Al Wasil primary
substations
8 SH 02/2013Construction of new Samad 2 x 20 MVA primary
substationMudhaibi 2019 Execution stage
Relieve the load from existing
Samad primary substation
9 SH 02/2013Construction of new Al Khadhra 2x20 MVA primary
substationMudhaibi 2019 Execution stage
Relieve the load from existing Al
Khadhra primary substation
10 SH 05/2012Construction of Samad 132/33 kV grid station 2x125
MVA with 33 kV outgoing feedersMudhaibi 2019 Execution stage
Relieve the load from existing
Mudhaibi grid station
11 SH 05/2012Construction of new Saih Al Nama substation 2x20
MVA.Mudhaibi 2020 Designing Stage
Relieve the load from existing
Mudhaibi primary station
12 SH 05/2013Construction of the proposed Bidayah 132/33 kV grid
station 2x125 MVA in with related 33 kV feedersBidayah 2020 Designing Stage
Relieve the load from existing
Mudhairib grid station
13 NSH 01/2017Construction of Ibra Flaje Primary 2x 20 MVA
substationIbra 2020 Designing Stage
Relieve the load from existing
Massroon primary station
14 SH 05/2012Construction of new Sinaw-C 3 x 20 MVA primary
substationMudhaibi 2020 Designing Stage
Relieve the load from existing
Sinaw and Sinaw-B primary
substations
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 34
20
18
-
2
02
0
Table 13: Sponsor Project in Al Dakhilyiah
Table 14: Sponsor Project in South Al Sharqyiah
No. Reference No. Project Name District Expected
completion Year Project Status Target
1 CC/01/2015Upgrading ROP Acadmy substation from 1x6 MVA to 3x6
MVA with new 33 kV feeder from Nizwa Grid.Nizwa 2018 Commissioning Stage
To supply the requested load of
ROP Acadmy
No. Referance No. Project Name District Expected
completion Year Project Status Target
1CC/27/2015 Construction of Aseelah IWP 2x6 MVA primary
substationJalan BB Ali 2018 Commissioning Stage
To supply the requested load of
IWP for water project in Jalan
BB Ali area
2CC/08/2016 Construction of ROP Headquarter 3x6 MVA primary
substation with one dedciated 33kV feeder in Sur areaSur 2019 Designing Stage
To supply the requested load
from ROP for a Headquarter in
Sur area
3CC/05/2014 Construction of Sur ROP 3x6 MVA primary
substation in Sur areaSur 2019 Designing Stage
To supply the requested load of
ROP buildings in Sur area
4CC/28/2015 Construction of Diar Ras Al Hadd 2x20 MVA primary
substation in Sur areaSur 2019 Designing Stage
To supply the requested load of
Diar Ras Al Hadd in Sur area
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 35
20
18
-
2
02
0
Table 15: Sponsor Project in South Al Batinah
No. Offer No. Project Name District Expected
completion Year Project Status Target
1 CC/22/2015
Construction of Suwaiq ROP 2x6 MVA substation to fed
New ROP project with new 33 kV feeder from Khadra
Grid and link from Marble Factory 33 kV feeders
Suwaiq 2018 Execution stageTo supply the requested load of
ROP Suwaiq
2 CC/12/2014South Al Batinah Logistics 1x6 MVA substation to feed
the Logistics area at Nakhal area.Nakhal 2018 Execution stage
To supply the requested load of
South Al Batinah Logistics
3 CC/04/2015Constructing two 2x20MVA substations for Barka IWP
with two 33kV feeders from Hai Asem Grid Barka 2018 Commissioning Stage
To supply the requested load of
Barka IWP
4 CC/10/2016Construct a new 3x6 MVA substation to supply the
sponsor project of ROP Wadi Al Mawel complex.Nakhal 2018 Execution stage
To supply the requested load of
ROP Wadi Al Mawel
5 CC/4/2017Construction of Barka Water Pump Temp. 1x6 MVA
substationBarka 2018 Execution stage
To supply the requested load of
Barka Water Pump
6 CC/4/2016Construction of Rustaq Sport Cmplex Temp. 1x6 MVA
substationRustaq 2018 Execution stage
To supply the requested load of
Rustaq Sport Cmplex
7 CC/4/2017Construction of Barka Water Pump 2x20 MVA substation
with two 33 kV feeders from Hai Asem GridBarka 2019 Designing Stage
To supply the requested load of
Barka Water Pump
8 CC/5/2017Construction of Al Hazam Water Pump 2x6 MVA
substation with 33 kV feeders from Muladah GridMusnah 2019 Designing Stage
To supply the requested load of
Al Hazam Water Pump
9 CC/7/2016
Construct Sandan 3x6 MVA substation with two
dedicated 33kV feeders from Madinat Barka-A grid
station
Barka 2019 Designing StageTo supply the requested load of
Sandan project
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 36
20
18
-
2
02
0
Table 16: Sponsor Project in North Al Sharqyiah
No. Referance No. Project Name District Expected
completion Year Project Status Target
1
CC/14/2014 Construction of Ibra ROP 2x6 MVA primary substation Ibra 2018 Commissioning StageTo supply the requested load of
ROP buildings in Ibra area
2
CC/22/2014 Construction of Al Zain Poultry Farm 1x6 MVA
primary substationMudahibi 2018 Commissioning Stage
To supply the requested load of
Al Zain Poultry Farm in
Mudhaibi area
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 37
20
18
-
2
02
0
14. Assessment of 33 KV Technical Losses
For the assessment of the technical losses on MZEC’s 33 KV network, the results of the load flow
analysis for the years 2018-2020 i.e. (Summary of Total Generation, Loading & Demand) are used.
The total demand, the apparent losses and the percentage losses for the years 2018-2020 are
shown in Table 17 below.
Table 17 : MZEC’s Total Demand and 33 KV Network Losses 2018-2020
No. Year Governorate Total
Demand (MW)
Total Losses (MW)
Percentage Losses (%)
1 2018
Al Dakhliyah 669.10 17.14 2.56
North Sharqiyah 344.44 14.66 4.26
South Sharqiyah 425.43 9.67 2.27
South Batinah 1000.11 18.90 1.89
Total : 2439.08 60.36 2.47
2 2019
Al Dakhliyah 701.26 16.40 2.34
North Sharqiyah 372.75 13.42 3.60
South Sharqiyah 467.12 11.65 2.49
South Batinah 1084.10 19.55 1.80
Total : 2625.23 61.02 2.32
3 2020
Al Dakhliyah 777.40 17.13 2.20
North Sharqiyah 396.69 10.32 2.60
South Sharqiyah 512.06 13.67 2.67
South Batinah 1171.20 17.88 1.53
Total : 2857.35 58.99 2.06
15. Network Suitability for New Connections
Taking a glance at the Equipment Loadings shown Annexure 1-A-1, 1-A-2, 1-B-1, 1-B-2, 1-C-1, 1-
C-2,1-D-1 and 1-C-2, it is seen that the 33 kV network and its components will be partially relieved
by the reinforcements programs. Despite the fact that for simple new connections which are defined
in the approved connection statement as those connections with a distance of less than 1.5 kilometer
and with a connected load of 2.5 MW or less, MZEC will not stop any application because of network
capability. On the other hand, for complex connections, the situation is totally different. In many
locations the network requires investments at grid level either in terms of additional capacity or
availability of circuit breakers. Further constraints are also at primary substations and 33 kV feeders
driven by the considerable growth experienced especially at the coastal part of South Al Batinah
Governorate, Nizwa in Al Dakhilyiah Governorate and parts of Al Sharqyiah (South and North)
Governorates.
Having said that, it is worth mentioning that a lot of uncertainty accompanies complex customers’
applications in terms of load and time for connections. Many applications were received since last
year capability statement and the seriousness of some is questioned. An example to that, a new
industrial area in Sumail requires large loads within a timeframe of few years which might require
investment at transmission network. On the other hand, such investment requires commitment from
applicants as well as accuracy in their applications. MZEC in this regard proposes to establish a
Distribution System Capability Statement 2018-2020
Mazoon Electricity Company SAOC Page | 38
20
18
-
2
02
0
mechanism to filter serious applicants from non-serious applicants. Once this mechanism is
approved and implemented, it will contribute significantly to plan for future investments.
The required reinforcements and the loadings of equipment shown in Annexure 1-A-1, 1-A-2, 1-B-1,
1-B-2, 1-C-1, 1-C-2, 1-D-1 and 1-C-2, give a clear picture of the anticipated constraints that may be
imposed on the 33 KV network. The load flow results for the years 2018, 2019 and 2020 are obtained
on the assumption that the current ongoing projects (CWIP) are completed on time and the planned
reinforcements are also delivered on time. Failure to finance these reinforcements or delay in timely
completion will impose further constraints on the network for the years 2018, 2019 and 2020.
16. Constraints
The required reinforcements and the loadings of equipment shown in in Annexure 1-A-1, 1-A-2, 1-
B-1, 1-B-2, 1-C-1, 1-C-2, 1-D-1 and 1-C-2 give a clear picture of the anticipated constraints that may
be imposed on the 33 KV network. The load flow results shown for the years 2018, 2019 and 2020
were obtained on the assumption that the current ongoing projects (CWIP) are expected to be
completed on time and the planned reinforcements are financed to bring them into operation. Failure
to finance these reinforcements or delay in timely completion will impose constraints on the network
for the three years.