FINAL YEAR (5TH YEAR) BSC. IN ELECTRICAL & ELECTRONIC

ENGINEERING RESEARCH PROJECT PRESENTATION

Submitted by: Noah Olela Abong’o

Student No: EN-5202S-00121/09 [Heavy Current Option]

Supervised by: Michael J. Saulo & Kenneth Mukhaya

25th February, 2013.

PROJECT TITLE:

THE ADOPTABILITY OF CAPACITOR – COUPLED SUBSTATION ON A DISTRIBUTION SYSTEM AS OPPOSED

TO A DISTRIBUTION TRANSFORMER

Secondary Distribution

Distributionsubstation

400 kV

40-70 kV

130 kV

11 kV

Transmissionsubstation

Main substation

415 V

Transformer

Table of Contents:Chapter 1 – Introduction

Chapter 2 – Literature ReviewChapter 3 – Research MethodologyChapter 4 – Research FindingsChapter 5 – RecommendationsChapter 6 – ConclusionChapter 7 – Work Plan & Budget

References / Bibliography Appendices

Chapter 1 - Introduction

• The provision of electric energy to many remote and/or rural people and communities is still today a big challenge for many developing countries, Kenya included.

• It is common knowledge that the provision of electricity, with whichever means, is one of the greatest enablers that allows the utilization of modern labour saving electric products and appliances.

Power system overview

The main purpose of power systems is to generate, transmit and distribute electric energy to customers without interruptions and in the most economical and safest manner possible.

Background Information

• The provision of electric services to rural and remote communities in the developing world is a financial challenge.

• This project is intended to study the adoptability of supplying electricity to rural communities directly from the high voltage transmission lines.

Objectives of the Research Project

These objectives are divided into two namely:

1. Main objectives.

2. Specific objectives.

Main objectives•Identify technologies which may lead to a

greater efficiency in the bulk power system distribution using the existing unexploited power system distribution utilization with a view of reducing system losses.

•Compare the adoptability of capacitor – coupled substation as opposed to the currently utilized conventional distribution transformer for the same locality.

Specific objectives• Power Stability considerations.

• Efficiency and Cost of Power Supply Systems under research.

• Undervoltage and Overvoltage Effects.

• Pilot projects using SimPowerSystems Simulations.

• Limitations and Assumptions made on Power Distribution Systems.

Rationale / Justification of study

•This project is intended to study the adoptability of supplying electricity to rural communities directly from high voltage transmission lines.

•This technique is anticipated to result in important cost reductions when compared with conventional distribution transformers which are currently costing an average of Ksh.1,300,000/= for a 60MVA transformer.

Rationale / Justification of study cont... Table 1.1 Estimates for a Distribution Transformer Installation

12

No. Item Description Quantity Unit Cost(Kshs.)

Total Cost(Kshs.)

1. 3Φ Transformer 60MVA

1 1,300,000 1,300,000

2. 3Φ Power Line and Neutral

4 X 50Km 8,000 1,600,000

3. 11Kv Busbar / CB/ Isolator

1 157,500 157,500

4. Earthing 1 175,000 175,000

5. Civil works 1 400,000 400,000

3,632,500

Rationale / Justification of study cont...Table 1.2 Estimates for Capacitor Divider Substation

13

No. Item Description Quantity Unit Cost(Kshs.)

Total Cost(Kshs.)

1. Capacitor C1 & C2 2 50,000 100,000

2. Feeder Transformer 250kVA 1 780,000 780,000

3. 11Kv Busbar / CB / Isolator 1 157,500 157,500

4. Earthing 1 175,000 175,000

5. Civil works 1 400,000 400,000

6. FSC 1 32,500 32,500

7. Inductor 1 18,000 18,000

1,663,000

Chapter 2 – Literature Review

•Technical information for this research project was obtained from :-

•Books on high voltage distribution systems and substations,

•Papers and bulletins electric power distribution.

•Mombasa Polytechnic University College electrical and electronic engineering notes.

•Library research reports.

Chapter 3 – Research Methodology

•SimPowerSystems® is one of the main software for modeling and simulating electric power systems in the Simulink® environment.

•It has powerful features for modeling generation, transmission, distribution and control systems, hence its choice for this research work.

Power System Stability

Power stability classification is important due to the following reasons:

1. Stability analysis leads to proper and effective understanding of different power system instabilities.

2. Key factors that lead to instability can easily be identified.

3. Methods can be devised for improving power system stability.

4. Considering the scope of this project, only voltage and frequency stability will be dealt with.

Voltage stability in power systems.

The voltage stability, sometimes called load stability is a major concern in planning and operating electric power system.

More electric utilities are facing voltage stability imposed limitations. Voltage instability and collapse have in the past resulted in several major system failures or blackouts.

Frequency stabilityFrequency stability refers to the ability of

a power system to maintain steady frequency following a severe system upset resulting in a significant imbalance between generation and load.

Frequency instability leads to tripping of generating units and / or loads.

Distribution System Issues.

Major issues related with flow of power in the distribution network can be categorized as:

•Voltage drop.

•Power loss.

•Power quality.

Distribution Transformer Simulation Circuit

powergui

Discrete,Ts = 5e-005 s

V-I M2VabcIabc

A

B

C

abc

V-I M1VabcIabc

A

B

C

abc

Three-Phase Source

A

B

C

Three-PhaseTransformer

(Two Windings)

A

B

C

a

b

c

Three-PhaseSeries RLC Load

Three-PhasePI Section Line

A

B

C

A

B

C

Scope 4

Scope 3

Scope 2

Scope 1

Scope

Isubc

Isubb

Isuba

Isc

i+ -

Isb

i+ -

Isa

i+ -

Ipc

i+ -

Ipb

i+ -

Ipa

i+ -

Gain 2

0.5

Gain 1

0.5

Gain

0.5

Graph 3.51 Current Display for Phase A

Table 3.51: Nominal condition transformer measurements

255.66 V -0.22° ---> V-I M1/Va 255.66 V -120.22° ---> V-I M1/Vb 255.66 V 119.78° ---> V-I M1/Vc 20343.40 V -0.17° ---> V-I M2/Va 20343.40 V -120.17° ---> V-I M2/Vb 20343.40 V 119.83° ---> V-I M2/Vc 6.88 A 107.75° ---> V-I M1/Ia 6.88 A -12.25° ---> V-I M1/Ib 6.88 A -132.25° ---> V-I M1/Ic 14.66 A 139.81° ---> V-I M2/Ia 14.66 A 19.81° ---> V-I M2/Ib 14.66 A -100.19° ---> V-I M2/Ic 14.66 A -40.19° ---> Ip1 14.66 A -160.19° ---> Ip2 14.66 A 79.81° ---> Ip3 6.88 A -72.25° ---> Isa 6.88 A 167.75° ---> Isb 6.88 A 47.75° ---> Isc

Capacitor – Coupled Substation Simulation Circuit

powergui

Discrete,Ts = 5e-005 s

VM5

v+-

VM4

v+-

VM3

v+-

VM2

v+-

VM1

v+-

T1

1 2

Source Resistance

Scope 1

Scope 8

Scope 7

Scope 6

Scope 5

Scope 4

Scope 3

Scope 2

Practical Load

Pi Section Line

L2

Current Limiting Resistor

CM3i+ -

CM2

i+ -

CM1i+ -

C2

C1

Breaker

AC Voltage Source

Graph 3.54 132KV Simulated Voltage Source

Table 3.52 Capacitor – Coupled Circuit Measurements

• 2017.93 V -79.78° ---> VM4 • 253.73 V -79.79° ---> VM3 • 116125.47 V -36.10° ---> VM2 • 63282.88 V -35.99° ---> VM1 • 132000.00 V 0.00° ---> VM5 • 2.54 A -80.00° ---> CM3 • 664.04 A 53.76° ---> CM2 • 795.24 A 54.01° ---> CM1

Chapter 4 – Research Findings• Simulation of Distribution Transformers

using SimPowerSystems Software.

• SimPowerSystems® Software in the Simulink / Matlab environment was used to simulate the Distribution Transformers. The parameter used for the simulation of these two distribution transformers were obtained from the theoretical work on high voltage and power systems analysis units.

Research Findings cont…

A Three-Phase 132/33KV, 45MVA power distribution system which included a 150Km transmission line was used for simulation of distribution transformer as shown in the Figure 4.10 below.

Figure 4.10 Simulated Transformer Power System Model

powergui

Continuous

V-I M1VabcIabc

A

B

C

abc

Three-Phase Source

A

B

C

Three-PhaseTransformer

(Two Windings)

A

B

C

a

b

c

Three-PhaseSeries RLC Load

Three-PhasePI Section Line

A

B

C

A

B

C

Scope 1

Scope e 1

Scope d 1

Scope c 1

Scope b 1

Scope a 1

Scope

Isubc

Isubb

Isuba

Isc

i+ -

Isb

i+ -

Isa

i+ -

Ip3

i+ -

Ip2

i+ -

Ip1

i+ -

Gain 2

0.5

Gain 1

0.5

Gain

0.5

V-I M2VabcIabc

A

B

C

abc

Figure 4.11 Three Phase Transformer Simulation Model

signals

powergui

Continuous

ic

i+ -

ib

i+ -

ia

i+ -

Va

v+- VA2

v+-

V -> pu

-K-V --> pu

-K-

node 992

node 991

Mux

Load10 MW 38 Mvar

A B C

Integrator

1s

Fourier

signalmagnitude

angle

Breaker3

Breaker2

Breaker1

1 MVA 220 kVEquivalent

N

A

B

C

0.15 MVA220 -490 kV

Three -PhaseTransformer

A

B

C

a

b

c

Fourier

Iabc

Flux

Analysis of the Results •The above circuit shows a three-phase

transformer with saturable core used for simulation.

•Both primary and secondary windings are connected in a star grounded configuration.

•Upon simulation the following surge voltage and inrush wave-forms were observed. The analysis of the Graph 4.10 and Graph 4.11 below are explained in details in the Data Analysis section.

Analysis of Results – Graph 4.10 cont…

Analysis of Results cont…•The Top waveform of Graph 4.10 shows the 4th

harmonic variation of the phase a voltage.

•The middle waveform shows the inrush current of all the three phases which reduces with time.

•The bottom waveform is the variation of the flux with changes in the inrush current. This shows that the flux build-up within the windings is directly proportional to the inrush current.

Analysis of Results – Graph 4.11 cont…Graph 4.11 Simulated Capacitive Inrush current

Analysis of Surge voltages / Inrush current of Capacitive-coupled circuits.

The simulation and measurements recorded indicate that the majority of surge voltages in low-voltage power systems have an oscillatory wave shape. This is because the voltage surge excites the natural resonant frequency of the wiring system. In addition to being typically oscillatory, the surges can also have different amplitudes and wave-shapes in the various places of the wiring system as can be observed in Graph 4.11 above.

Chapter 5 - RecommendationsEffects of power supply disturbances can be reduced to acceptable levels using the following methods:

a) The power distribution system should to be resistant to power disturbances and discontinuities.

b) The power distribution system must to be compatible with the utilization equipment.

c) Both power systems and utilization equipment to meet a criterion that is realistic for both.

Challenges encountered in research The major challenge of this research work has

been the scarcity of relevant and practical information and principles touching on implementation of capacitor - coupled substations.

The second challenge has been the identification of the right software that was able to successfully realize the intended objectives of the project research.

Further Research Work

The researcher endeavoured to ensure that the project scope is carried out to its logical end. However, this field of study still offers a lot of unexploited research opportunities which needs to be carried out to the next level.

Further research work cont…I propose the following critical areas for further research work:

Investigations into various causes of the power system instability and their possible mitigations.

The major systematic reasons for the deviations of the capacitance parameters in power distribution system.

Investigations into the possible permanent remedial actions to damp or remove the effects of ferroresonance effects.

Investigations into the impact system parameters for implementation of CCS .

Improvement of distribution transformer efficiency on a distribution system.

Chapter 6 – Conclusion

• Distribution transformers as that installed at Mombasa Polytechnic University College Electrical department may cost as much as Kshs.1,300,000/= as at today’s market price.

• This clearly explains why rural electrification schemes are usually uneconomical, especially where distribution transformers have been employed due to the high capital and operating costs. Furthermore, the loads are scattered and are characterized by low demand and poor utilization factors.

Chapter 7 – Project Work PlanActivity Description Predecessors Duration

(Weeks)A Select a project and Formulate Problem

Statement. - 2

B Collection of Relevant Literature - 6

C Literature Review and Analysis B 2

D Preparation of the Project Design C 3

E Collection of Data D 3

F Analysis of the Collected Data E 2

G Formulation of Results and Drawing of Conclusions

F 2

H Experimental Design, Software Simulation and Drafting of Final Report Outline

G 4

I Analysis of Data and Review of the Results against the Expectations

H 3

J Final Report Writing and Presentation. I 18

Project Time ScheduleActivity

June2012

July2012

Aug2012

Sept2012

Oct2012

Nov2012

Dec2012

Jan2013

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

A 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

B 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

C 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

D 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

E 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

F 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

G 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

H 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

I 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

J 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

Project BudgetNO DESCRIPTION ESTIMATED COST IN KSHS.

1. Feasibility studies on High Voltage Line 10,000.00

2. Designing / Printing of the Data Collection Tools 15,000.00

3. Cost of Software and Simulation of Data 17,000.00

4. Accessing of Internet and Cyber Cafés Charges 8,000.00

5. Production of Project Draft Copies 3,000.00

6. Production of the Final Project Dissertation and CDs 25,000.00

7. Miscellaneous / Concealed Expenses 10,500.00

Total Estimated Cost of the Entire Project 88,500.00

References / Bibliography[1] A Research Guide - University of Central England in Birmingham Published

by the Research Training Initiative [First Published in 1996][2] A.N.Zomers (NLD) and G.Dagbjartsson (CHE) The challenge of rural

electrification CIGRÉ’s strategy and organizational approach. [2006].[3] C.L. Wadhwa Electrical Power Systems [6th Edition – 2010][4] David A. N. Jacobson, Member, IEEE - Examples of Ferroresonance in a High

Voltage Power System. [1990][5] E. Liu and J. Bebic – [2008] National Renewable Energy Laboratory Report –

NREL/SR-581-42298 “Distribution System Voltage Performance Analysis for High-Penetration Photovoltaics”

[6] Edvard Csanyi –Substations Main Functions and Classifications. [2012][7] Edward R. Ronan, Member, IEEE, Scott D. Sudhoff, Member, IEEE, Steven

F. Glover, and Dudley L. Galloway, Member, IEEE A Power Electronic-Based Distribution Transformer. [2002]

[8] Government of the Republic of Kenya Vision 2030 Delivery Secretariat Kenya Vision 2030 – Chapter 2 Foundations for Socio-Economic Transformation. [2006]

[9] Jennifer M. Case and Gregory Light in Emerging Methodologies in Engineering Education Research [2011]

[10] L. Pillay – Research Manager Research Report No: RES/PR/04/23205 “Analysis of Tests Results for the 275 to 22KV Meru Capacitor Coupled Sub-Station” [2004]

[11] M. Sanaye-Pasand and R. Aghazadeh Capacitive Voltage Substations Ferroresonance Prevention Using Power Electronic Devices. [2003]

References / Bibliography cont…[12] Ningbo SanXing Electric Company Limited – Available at:

www.sanxing- energymeter.com/product.asp[13] P. R. Barnes et al –Electric Utility Industry Experience with

Geomagnetic Disturbances. [November 1991] [14] Pandey Piyush - Substation Practice [2010][15] Pant, Gourav – A Seminar on Ferroresonance in High Voltage Power

Systems[16] Peter Johansen: Substation Monitoring and Control. Available at:

www.jomitek.dk.[17] Prabha Kundur, John Paserba, “Definition and Classification of

Power System Stability”, IEEE Trans. on Power Systems. Vol. 19, No. 2, [2004]

[18] Siemens Energy Sector – Power Engineering Guide – Edition 7.0[19] Swee Peng Ang [2010] Ferroresonance Studies of Transmission

Systems.[20] The Point – Bulletin of the Institute of Economic Affairs – Issue

No.56 [April 2003] Available at: http://prr.hec.gov.pk/Chapters/543S-2.pdf

[21] Trevor Gaunt (South Africa) et al Paper on the “Innovative Solutions and Best Practices for Rural Electrification of Remote Areas”. [2007].

[22] Viktor M. Perelmuter, PhD Electrotechnical Systems: Simulation with Simulink and SimPowerSystems [16th October, 2012]

Appendices

Appendix I Glossary

Appendix II Introduction to Simulink

Appendix III Introduction to SimPowerSystems®

THANK YOU!Questions?