APROJECT REPORTON

LOAD DESPATCH & SYSTEM OPERATION MANUAL

Submitted in Partial Fulfillment for the Award ofBachelor of Technology (B.Tech.) DegreeOfRajasthan Technical University, KOTA

2012-2013

Submitted to: Submitted By: SHREY PARASHAR Designation EEE, Deptt.

DEPARTMENT OF ELECTRICALENGINEERINGSINE INTERNATIONAL INSTITUTE OF TECHNOLOGYLAKHNA ROAD VIA SAGANER BAJARJAIPUR-302029(RAJASTHAN)

PREFACE

I, SHREY PARASHAR student of fourth year EEE have completed practical (In-plant) training at Rajasthan,Heerapura LOAD DESPATCH & SYSTEM in period of 45 days. As I am student of Engineering stream, so the training at Rajasthan,Heerapura LOAD DESPATCH & SYSTEM in has been particularly beneficial for me. I saw various processes and equipments used in production of electricity that were studied in books and this had help me in understanding of power generation and various aspects related to it.

Acknowledgement It was highly educative and interactive to take training at Rajasthan Heerapura LOAD DESPATCH & SYSTEM as technical knowledge is incomplete without the practical knowledge, I couldnt find any place better than this to update myself. I am highly grateful to the our Training Co-coordinator Mr. Amitabh ji (Training Co-coordinator) to grant me permission to take training at such a coveted institute. Apart from him, there was always a friendly guidance from Mr. Ajay Patidar (H.O.D OF ELECTRICAL Dept. ) for the betterment of this Training Report. I am also thankful to all those engineers and technicians without whom it was not possible for me to clear my doubts and difficulties. After coming to this institute and knowing State of Art Technology available with learned Training staff, I would like to come again to this coveted institute if got a chance.

SHREY PARASHARIV-YEAR S.I.I.TJAIPUR

RAJASTHAN RAJYA VIDYUT PRASARAN NIGAM LTD.STATE LOAD DESPATCH CENTRELOAD DESPATCH & SYSTEM OPERATION MANUALCONTENTS1 OVERVIEW

2 EXISTING POWER SYSTEM AND LOAD DESPATCH FACILITY

3 CURRENT BLACK START AND SYSTEM RESTORATION PROCEDURES

4 EXISTING ISLANDING SCHEMES

5 DEMAND ESTIMATION AND CONTROL

6 NETWORK SECURITY AND SYSTEM OPERATION

7 OUTAGE PLANNING

8 SCHEDULING AND DESPATCH PROCEDURE

9 GRID DISTURBANCES AND REVIVAL

10 ENERGY ACCOUNT AND SETTLEMENT SYSTEM.

11 EVENT INFORMATION AND REPORTING

12 MANAGEMENT OF LOAD DESPATCH & SYSTEM OPERATION CODE

13 Bibliography

ANNEXURESANNEXURE2.1 RAJASTHAN SHARE/ ALLOCATION IN ISGS FOR A TYPICAL DAY ANNEXURE3.1 RESTORATION STAGE IN RAJASTHAN SUB-SYSTEM ANNEXURE3.2 START UP SEQUENCE IN RAJASTHAN SUB-SYSTEM ANNEXURE3.3 PRIORITY OF LOAD RESTORATIONANNEXURE4.1 SINGLE LINE DIAGRAM OF RAPS-A ISLANDING SCHEME ANNEXURE4.2 SINGLE LINE DIAGRAM OF RAPS-B ISLANDING SCHEMEANNEXURE5 POWER MAP OF RAJASTHAN

ABBREVIATED TERMS

ABTAvailability Based Tariff

AVVNLAjmer Vidyut Vitran Nigam Ltd.

AVRAutomatic Voltage Regulator

BBMBBhakra Beas Management Board

CBSCentral Billing Station

CERCCentral Electricity Regulatory Commission

CPPCaptive Power Plant

CTUCentral Transmission Utility

DCCPPDholur Combined Cycle Power Project

DISCOMJaipur or Jodhpur or Ajmer Vidhyut Vitaran Nigam Limited

EA 2003Electricity Act 2003

EMSEnergy Management System

GSSGrid Sub-station

HEPHydro Electric Power Plant

HzHertz

IEGCIndian Electricity Grid Code

ILTInter Linking Transformer

IPPIndependent Power Producer

ISGSInter State Generating Station

ISTSInter State Transmission System

Jd.VVNLJodhpur Vidyut Vitran Nigam Ltd.

JSJawahar Sagar

JVVNLJaipur Vidyut Vitran Nigam Ltd.

KSTPSKota Super Thermal Power Station

kVKilo Volt

LDLoad Despatch

LDCLoad Despatch Centre

LD&SOMLoad Despatch and System Operation Manual

LULakh Units

MUMillion Units

MVArMega Volt Ampere Reactive

MWMega Watt

MWhMega Watt Hour

NHPCNational Hydro Power Corporation

NLDCNational Load Despatch Centre

NTPCNational Thermal Power Corporation

NRPCNorthern Regional Power Committee

NRLDCNorthern Regional Load Despatch Centre

OCCOperation Coordination Sub Committee

OFCOptical Fiber Cable

OLTCOn Load Tap Changer

PGCILPower Grid Corporation of India Limited

PLCCPower line carrier communication

PTWPermission to work

RAPS/RAPPRajasthan Atomic Power Station /Plant

REGCRajasthan Electricity Grid Code

RERCRajasthan Electricity Regulatory Commission

RLDCRegional Load Despatch Centre

RLSSRotational Load Shedding Scheme

RPSRana Pratap Sagar

RTURemote Terminal Unit

RVPNRajasthan Rajya Vidyut Prasaran Nigam Limited

RVUNRajasthan Rajya Vidyut Utpadan Nigam Limited

SCADASupervisory Control And Data Acquisition System

SGSState Generating Station

SLDCState Load Despatch Centre

SPCState Power Committee

SSTPSSuratgarh Super Thermal Power Station

STSState Transmission System

STUState Transmission Utility

TODTime Of Day

UFRUnder Frequency Relay

UIUnscheduled Interchange

ULDCUnified Load Despatch & Communication

UPUttar Pradesh

UTUnion Territory

UTILITYRVPN, RVUN OR DISCOM or any other distribution or Transmission Licensee or Generating Company, referred Individually

VARVolt Ampere Reactive

VDUVisual Display Unit

WRWestern Region

Chapter-1Overview1.1 Introduction1.1.1 Rajasthan State Power System is the part of Northern Regional Grid which operatesin synchronous with Eastern, Western & Northern Eastern Grid. Northern RegionalGrid System consists of power systems of constituent States of Haryana, Punjab,Rajasthan, Uttar Pradesh, Uttrakhand, Himachal-Pradesh, Delhi, Jammu andKashmir and Union Territory of Chandigarh. It includes Inter-State GeneratingStations of NTPC, NHPC, Nuclear Power Corporation (NPC), Partnership projects,IPPs, other generating companies, Inter-State Transmission System of PGCIL andtransmission system of BBMB.1.1.2 Rajasthan State Power System consists of generating stations of RVUN, CaptivePower Stations, IPPs, other generating companies, partnership projects, ISGSlocated within state, distribution network of three Discoms namely JVVNL, AVVNLand JdVVNL.1.1.3 The highlights of Rajasthan Power System and load despatch facility at SLDC havebeen described at Chapter 2.1.2 Role of NLDC and NRLDC in the Northern Regional GridThe role of various agencies operating in the National Grid and Northern RegionalGrid and their organisational linkages with RVPN and the SLDC as per Electricity Act2003 is briefly described below :-1.2.1 National Load Despatch Centre (NLDC)According to Section 26(2) of the Act the Ministry of Power, Government ofIndia has vide notification dated 2nd March 2005 prescribed the functions ofNLDC as under:(a) Supervision over the Regional Load Despatch Centres.(b) Scheduling and despatch of electricity over inter-regional links inaccordance with grid standards specified by the Authority and grid codespecified by Central Commission in coordination with Regional LoadDespatch Centres.(c) Coordination with Regional Load Despatch Centres for achievingmaximum economy and efficiency in the operation of National Grid.(d) Monitoring of operations and grid security of the National Grid.(e) Supervision and control over the inter-regional links as shall be requiredfor ensuring stability of the power system under its control.(f) Coordination with Regional Power Committees for regional outageschedule in the national perspective to ensure optimal utilization of powerresources.(g) Coordination with Regional Load Despatch Centres for the energyaccounting of inter-regional exchange of power.(h) Coordination for restoration of synchronous operation of national grid withRegional Load Despatch Centres.(i) Coordination for trans-national exchange of power.(j) Providing operational feedback for national grid planning to the Authorityand the Central Transmission Utility.(k) Levy and collection of such fee and charges from the generating companies or licensees involved in the power system, as shall be specified by the Central Commission.(l) dissemination of information relating to operations of transmission systemin accordance with directions or regulations issued by Central ElectricityRegulatory Commission and the Central Government from time to time.1.2.2 Northern Regional Load Despatch Centre (NRLDC)(i )NRLDC is the apex body engaged in the activities of integrated operation of powersystem of the Northern Region.(ii) The Regional Load Despatch Centre shall comply with such principles,guidelines and methodologies in respect of wheeling and optimum scheduling anddespatch of electricity as the Central Commission may specify in the Grid Code.(iii) The Regional Load Despatch Centre shall -a) Be responsible for optimum scheduling and despatch of electricity within theregion, in accordance with the contracts entered into with the licensees or thegenerating companies operating in the region;b) Monitor grid operations;c) Keep accounts of quantity of electricity transmitted through the regional grid;d) Exercise supervision and control over the inter-state transmission system;ande) Be responsible for carrying out real time operations for grid control anddespatch of electricity within the region through secure and economicoperation of the regional grid in accordance with the Grid Standards and theGrid Code.(iv) Compliance of directions of RLDC under Section 29 of the Act.(1) The Regional Load Despatch Centre may give such directions andexercise such supervision and control as may be required for ensuringstability of grid operations and for achieving the maximum economy andefficiency in the operation of the power system in the region under itscontrol.(2) Every licensee, generating company, generating station, sub-stationandany other person connected with the operation of the power system shallcomplywith the directions issued by the Regional Load Despatch Centres undersubsection (1).(3) All directions issued by the Regional Load Despatch Centres to anytransmission licensee of State transmission lines or any other licensee oftheState or generating company (other than those connected to inter Statetransmission system) or sub-station in the State shall be issued throughthe StateLoad Despatch Centre and the State Load Despatch Centres shall ensurethat such directions are duly complied with the licensee or generatingcompany or sub-station.(4) The Regional Power Committee in the region may, from time to time,agree on matters concerning the stability and smooth operation of theintegrated grid and economy and efficiency in the operation of the powersystem in that region.(5) If any dispute arises with reference to the quality of electricity or safe,secure and integrated operation of the regional grid or in relation to anydirection given under sub-section (1), it shall be referred to the CentralCommission for decision :Provided that pending the decision of the Central Commission, thedirections of the Regional Load Despatch Centre shall be complied withby the State Load Despatch Centre or the licensee or the generatingcompany, as thecase may be.(6) If any licensee, generating company or any other person fails tocomply with the directions issued under sub-section (2) or sub-section (3),he shall be liable to a penalty not exceeding rupees fifteen lacs.1.2.3 Regional Load Despatch Centre may levy and collect such fee and charges from thegenerating companies or licensees engaged in inter-state transmission of electricityas may be specified by the Central Commission.1.3 State Load Despatch Centre (SLDC) :1.3.1 The State Load Despatch Centre is the apex body to ensure integrated operation ofthe power system in a State as per section 32 of EA 2003 .1.3.2 The State Load Despatch Centre shall be responsible for -(i) Optimum scheduling and despatch of electricity within State, in accordancewith the contracts entered into with the licensees or the generating companiesoperating in the State;(ii) Monitor grid operations;(iii) Keep accounts of quantity of electricity transmitted through the state ;(iv) Exercise supervision and control over the intra-state transmission system;and(v) Be responsible for carrying out real time operations for grid control anddespatch of electricity within the State through secure and economicoperations of the state grid in accordance with the Grid Standards and theGrid Code (s).1.3.3 The State Load Despatch Centre which is responsible for coordinating thescheduling of a generating station shall also be responsible for(i) real- time monitoring of the stations operation,(ii) Checking that there is no gaming in its availability declaration,(iii) Revision of availability declaration and injection schedule,(iv) Switching instructions,(v) Metering and energy accounting,(vi) Issuance of UI accounts,(vii) collections/disbursement of UI payments,(viii) outage planning, etc.1.3.4 The State Load Despatch Centre may levy and collect such fee and charges from theGenerating companies or licensees engaged in intra-state transmission of electricityas may be specified by the State Commission.1.3.5 Role of SLDC towards open access suppliers and open access consumers shall beas under:-i) Facilitating transactions of power under short term and long term intra-stateopen access as approved by STU.(ii)Issuing No Objection Certificate/Standing Clearance for inter-state openaccess transactions and facilitating the same consequent upon the approval fromNodal RLDC1.3.6 Compliance of directions of SLDC under section 33 of the Act :(1) The State Load Despatch Centre in a State may give such directions and exercisesuch supervision and control as may be required for ensuring the integrated gridoperations and for achieving the maximum economy and efficiency in the operation ofpower system in that State.(2) Every licensee, generating company, generating station, sub-station andany other person connected with the operation of the power system shall complywith the directions issued by the State Load Despatch Centre under sub-section(1).(3) The State Load Despatch Centre shall comply with the directions of the RegionalLoad Despatch Centre.(4) If any dispute arises with reference to the quality of electricity or safe,secure and integrated operation of the State grid or in relation to any directiongiven under sub-section (1), it shall be referred to the State Commission for decision:Provided that pending the decision of the State Commission, thedirections of the State Load Despatch Centre shall be complied with by thelicensee or generating company.(5) If any licensee, generating company or any other person fails to complywith the directions issued under sub-section(1), he shall be liable to a penaltynot exceeding rupees five lacs.1.4 Indian Electricity Grid Code (IEGC)1.4.1 The Indian Electricity Grid Code (IEGC) lays down the rules, guidelines andstandards to be followed by the various agencies that connect with and/or utilise theISTS. IEGC provide a common basis to plan, develop, maintain and operate thepower system in the most efficient, reliable and economic manner, while facilitatinghealthy competition in the generation and supply of electricity in the Country.1.4.2 Salient Provisions of IEGC(i) Under section 1.3 (1) of IEGC, utilities connected with interstate transmission system(ISTS), are to abide by the various provisions as defined in IEGC so far as theyapply to that utility.(ii) All generating units, which are synchronized with the grid, irrespective of theirownership, type and size, shall have their governors in normal operation at all times.If any generating unit of over fifty (50) MW size is required to be operated without itsgovernor in normal operation, the NRLDC shall be immediately advised about thereason and duration of such operation. All governors shall have a drop of between3% and 6%. The exemption from free governor mode operation in respect of anygenerating stations may be granted only by CERC under clause 1.6 of IEGC, forwhich the concerned constituent/agency shall file a petition in advance. (iii) Under Clause 5.1 (e) of IEGC, Control Rooms of NRLDC, all SLDC, power plants,substation of 132 kV & above and any other control centres of regional constituentsshall be manned round the clock by qualified and adequately trained personnel.(iv) Following chapters of IEGC set out the demarcation of responsibilities betweenNRLDC & SLDC and role of SLDC:Chapter 4 - Connection conditionsChapter 5 - Operating code for regional gridChapter 6 - Scheduling & despatch code1.5 Rajasthan Electricity Grid Code (REGC)1.5.1 In exercise of power conferred under 181 read with section 86(1) (h) of EA 2003,RERC has issued RERC (Rajasthan Electricity Grid Code) Regulation 2008. Theseregulations shall apply to the users of 33 kV and above, which includes transmissionlicensee, generating station located in the State including independent powerproducers, renewable energy power plants, generating or/and transmissioncompanies connected to State Transmission system, distribution companies havingHV/EHV consumers directly connected to State Transmission System, open accesscustomers interconnected to State transmission system and traders. REGC laysdown the rules, guidelines, and standards to be followed by the users to operate andmaintain an efficient and coordinated State Transmission System and to allow StateTransmission Utility (STU) and State Load Dispatch Center (SLDC) to comply withthe obligations in relation to the inter-state transmission of power and to operate thesystem in integration with the Northern Grid as per the provisions of Indian ElectricityGrid Code.1.5.2 Role of SPCThe SPC shall be responsible for facilitating the implementation of the rules andprocedures developed under the provisions of REGC and for Review operation ofREGC regularly and recommend amendment, if any.The SPC proceedings shall be based on the Rules to be followed by the Committeeconducting their business which shall be formulated by the Committee themselves.SPC shall review and approve (wherever required) the reports submitted by Subcommitteesand shall analyze any major Grid Disturbance, soon after its occurrence,and suggest remedial measures and issue directives to Users for implementation.SPC shall also approve guidelines for load shedding through under frequency relaysor otherwise prepared by the Technical Committee.1.6 Load Despatch & System Operation Manual (LD & SOM)1.6.1 This Load Despatch and System Operation Manual has been prepared incompliance to directions contained at clause No.2.1.1 of REGC issued by RERCvide its notification dated 24.5.2008 to ensure that SLDC manages the RajasthanPower System effectively and efficiently in conformity with IEGC and RajasthanElectricity Grid Code. The Load Despatch and System Operation Manual is adocument to be complied with by all Users, STU and the SLDC. This Manual willprovide guidelines and instructions to SLDC personnel and other officials. The LoadDespatch and System Operation Manual defines responsibilities of SLDC otherusers personnel in operating matters and in interface with external agencies, viz.NRLDC, SGSs, IPPs, CPPs, RVPN, Trading licensees and Distribution Companies.1.6.2 The role of SLDC with reference to users (viz. Discoms, RVUN, other licensee orgenerators within the state but excluding ISGS) is analogous to that of NRLDC andother constituents of the Northern grid. This Manual brings out salient features ofexisting facility, principles governing the operation of integrated power system inaccordance with IEGC, REGC, SLDC and the operating procedures issued byNRLDC. The Load Dispatch and System Operation Manual is a dynamic documentrequiring frequent changes based on augmentation of facility, amendment to IEGCand REGC, mutual agreements between utilities, Regulatory Commissionsdirectives etc.1.7 Definition & interpretation1.7.1 The terms used in the LD & SOM shall have the meaning as defined in the REGC.The terms, which are used in this LD&SO Manual and not defined in the RajasthanElectricity Grid Code, will have the same meaning as defined in IEGC.1.7.2 The LD & SOM is prepared such that it is consistent/ compatible with REGC andIEGC. If any provisions of the Load Despatch and System Operation Manual areinconsistent with the provisions of the REGC, then the provisions of REGC shallprevail in case of intra-state transmission network. However, in the matters relating tointerstate transmission network, if any provision of LD & SOM is inconsistent with theprovisions of IEGC, then the provisions of IEGC shall prevail.1.8 Redressal mechanism1.8.1 All grievances relating to Open Access consumers:i) shall be investigated by SLDC and efforts will be made to resolve the samewithin 30 days, andii) In case SLDC is unable to resolve a grievance, the O.A. consumer mayapproach SPC within 15 days to resolve the grievances. The SPC willresolve the grievance in 30 days, andiii) Where SPC is unable to resolve the grievance in the time, the aggrieved OAconsumer may approach the Commission within next 15 days.1.8.2 The SPC will look in to the problems raised by users and resolve the disputes.1.8.3 The disputes relating to the quality of Electricity or safe, secure and integratedoperation of state grid or about the directions given by SLDC, shall be referred to theCommission.

Chapter-2

Existing Power System and Load Despatch Facility

2.1Generation Capacity within State:

2.1.1Major generating Stations operating in the State are mentioned below:-

S.No.Name of Generating StationUnitRatings& NosTotal capacityMW

(A) RVUN

1

Kota Super Thermal Power Station (KSTPS)2 X 110 MW3 X 210 MW1 X195 MW

1045 MW

2SuratgarhSuperThermalPowerStation(SSTPS)5 X 250 MW1250 MW

3

Ramgarh Gas Thermal Power Station (RGTPS)1 X 3.0 MW1 X 35.5 MW1 X 37.5 MW1 X 37.5 MW

113.5 MW

4Giral LTPS1 X 125 MW125 MW

5Dholpur CCPP3 X 110 MW330 MW

6Mahi Hydel Power Station-I (Mahi-PH-I)2 X 25 MW50 MW

7Mahi Hydel Power Station-II (Mahi-PH-II)2 X 45 MW90 MW

(B) RVPN -Partnership Projects in State

1Ranapratap Sagar Hydel Power Station (RPS)4 X 43 MW172 MW

2Jawahar Sagar Hydel Power Station (JS)3 X 33 MW99 MW

(C) NTPC Projects in State

1Anta Gas Power Station (Anta GPS)3 X 88.71 MW1 X 153.2 MW419.3 MW

(D) NPC Projects in State

1Rajasthan Atomic Power Station-A (RAPS-A)1 X 100 MW1 X 200 MW300 MW

2Rajasthan Atomic Power Station-B (RAPS-B)2 X 220 MW440 MW

Note :- 1. RPS and JS power stations are part of Chambal-Satpura Project inpartnership between Rajasthan & M.P. Rajasthans share is 50% in hydelprojects and 40% in Satpura TPS-stage-I. RPS and JS power stations areowned by RVPN but operated and maintained by RVUN and two otherpower stations of partnership projects viz. Gandhisagar Hydro power station(5x23 MW) and Satpura TPS -stage-I (5x62.5 MW) are owned, operatedand maintained by MP.2. RAPS Unit 1 (100 MW) and RGTPS (3 MW) are presently not in operation.3. Sr. No. (C) and (D) above are Central Sector Generating Stations located inthe State. RAPS- A is operated and maintained by NPC in which Rajasthanhas 100% allocation.2.1.2 Rajasthan have partnership in Bhakra & Beas Projects also and gets its partnershipshare of 15.22% in Bhakra, Gangwal and Kotla Hydel Power Stations (Capacity1480.30 MW), 20% in Dehar Hydro Power Station (Capacity 990 MW) and 58.5% inPong Hydel Power Station (Capacity 396 MW) through common transmission systemof Bhakra and Beas Projects. These Power Stations and transmission system areoperated and maintained by Bhakra & Beas Management Board (BBMB).2.1.3 Rajasthan have firm allocations in various central sector power stations. Besides this,temporary allocations from unallocated capacity are also made from time to time byGovernment of India/CEA. The list of ISGS generating stations in which Rajasthanhas shares/allocations is given at Annexure-2.12.1.4 The RVPNs EHV transmission system as on 31stMarch 2008 consists of 4 Nos. 400kV Sub-stations, 57 Nos. 220 kV Sub-stations and 267 nos. 132 KV GSSs.2.2 Inter-State Transmission SystemRajasthan Power System is inter-connected with Inter-State Transmission Systemthrough following tie lines/ICTs:-i) 400 kV Bassi- Heerapura- I & IIii) 220 kV Badarpur- Alwariii) 220 kV Bharatpur -Agraiv) 220 kV Dadri- Khetri- I & IIv) 220 kV Hissar- Khetrivi) 220 kV Kota-Badodvii) 220 kV Modak- Badodviii) 132 kV RPS-Gandhi Sagar I&IIix) 2 Nos. 315 MVA, 400/220 kV ICTs At 400 kV GSS Bassix) 2 Nos. 315 MVA, 400/220 kV ICTs At 400 kV GSS Bhiwadi2.3 Load Despatch Facility2.3.1 The State Load Despatch Centre (SLDC) of Rajasthan is functioning at Heerapura(Jaipur). The SLDC has communication links with NRLDC, all major generatingstations and important sub-stations for system operation and load despatch function.Basic data, necessary for System Operation, are available in the LD Control Roomthrough the existing ULDC system. PLCC is main communication channel betweenSub LDC and RTU stations. Microwave has been used as data communication linkLast Updated : 30-06-2009- 12 -between Sub-LDCs and SLDC at Heerapura. At few locations OFC links have alsobeen provided for data transfer. The communication link between SLDC and NRLDCis through optical fiber cable. The on-line flow of MW, MVAR of the inter-state tielines, generating stations, 220 kV/132 kV Grid Sub-stations etc. is being monitored atthe SLDC Heerapura round the clock. On line data are displayed on screen ofoperator consoles in the LD Control Room. ULDC has facility for displaying the MW,MVAR flows on single-line diagram of respective stations along with digital status ofbreakers and isolators etc. These online screens displaying data and single linediagrams can be modified/ reprogrammed if required. The RTUs are timesynchronized by GPS installed at SLDC Heerapura and Sub-Load despatch centresat Kota ,Ratangarh & Bhilwara2.3.2 The various data such as MW and MVAR of various sub-stations, lines are beingtransmitted to the SLDC at Heerapura through 73 Nos. RTUs functioning atvarious stations. As per the scheme, under System Co-ordination & Control Northern Region Project four sub Load Despatch Centers at Heerapura, Kota,Ratangarh and SLDC at Heerapura were established for on-line transmission ofelectrical data of various 400 /220/132 kV GSS and generating stations fallingunder each of Sub Load Despatch Center. As per scheme, following RTUs havebeen installed at various GSSs/Generating stations and integrated with the SubLoad Despatch Centers.i) 26 RTUs at Sub LDC , Heerapuraii) 11 RTUs at Sub LDC , Kotaiii) 12 RTUs at Sub LDC , Ratangarhiv) 24 RTUs at Sub LDC , Bhilwara2.3.3 In the present set-up, line flows on various important transmission lines with theNorthern Grid, generation data from major power stations as well as mimic diagramsof 400 kV and several 220 kV Sub-Stations are available on the monitors which alsodisplay the scheduled drawl from NR Grid vis-a-vis actual load flows on 400/220 kVlines. This enables monitoring of deviations in injection and drawl with respect toschedule and estimates of energy in to the grid, which is essential to enable theSLDC to regulate the generation of various SGS or load of Discoms.2.3.4 In addition to this, important on-line data of Central sector generating stations &BBMB stations, relevant to RVPN, are being received from NRLDC. The ULDCScheme has provision of remote control operation of circuit breakers etc. fromSLDC/NRLDC Control Room but the operation thereof has not been activated.Additionally, EMS function, Contingency Analysis, Scheduling and weather basedload forecasting are available under ULDC Scheme which are also yet to beactivated.

Chapter-3Current Black Start and System Restoration Procedures3.1 OverviewA 'Grid Disturbance' denotes the situation under which a set of generatingunits/transmission elements trip in an abrupt and unplanned manner affecting thepower supply in a large area and/or causing the system parameters to deviate fromthe normal values in a wide range. In the event of a grid disturbance, utmost priorityis to be accorded to early restoration/revival of the system. It is possible that duringsuch a situation the system may have to be operated with reduced securitystandards and suspension of all commercial incentives/penalties.This chapter is based on System Restoration Procedures for Northern Regional Gridbrought out by NRLDC. The classification of grid disturbance is given at Chapter-9.This chapter describes the existing system restoration procedure for Rajasthansystem and general guidelines and precautions for system revival.3.2 Northern Regional Grid System Restoration Procedure OverviewThe Rajasthan Power System is the part of Northern Regional Grid and thereforeNorthern Regional Grid restoration procedure applies for Rajasthan System as well.The Northern Region consists of a large network. In the event of a total blackout,extending start-up power from one end of the region to the other end is ratherimpractical. The restoration of the system back to normal has to be achieved in asectionalized manner. Accordingly the Northern Region has been divided into 4 subsystemsfor system restoration process so that in the event of total grid failure,initially each subsystem is to be restored independently and once the subsystemsseparately built-up, these can be synchronised in stages to integrate into a completesystem.1. Restoration of Eastern UP Sub-system2. Restoration of North Central Sub-system3. Restoration of Rajasthan Sub-system4. Restoration of Western UP Uttrakhand Sub-systemThe restoration process for each sub-system can be divided into following steps:1. Sub-system Overview2. Sub-system restoration procedure3. Sub-system Synchronization4. Start-up stages and sequence in a sub-systemThe boundaries of sub-system have been defined on the criteria of most likelypossibility. However during actual operations there can be variation in these subsystemsand or sequencing depending upon the real time situations. The systemrestoration procedure in Rajasthan is required to be carried out in close co-ordinationwith NRLDC under the directions of SLDC while relating various options inprocedures.3.3 Restoration of Rajasthan Subsystem3.3.1. Subsystem Overview:1. Important Connecting Links with North-Central (NC) subsystema) 400 kV Ballabgarh - Bhiwadib) 400 kV Hissar - Bhiwadic) 400 kV Agra Bassid) 220 kV BTPS-Alware) 220 kV Agra- Bharatpurf) 220 kV Hissar-Khetrig) 220 kV Dadri Khetri I & II2. Major Generating Stations:a) Thermal: Suratgarh STPS, Kota STPS, Giral LTPSb) Hydel: Rana Pratap Sagar (RPS) PS, Jawahar Sagar (JS) PS, Mahi PH I & IIc) Gas: Anta, Ramgarh GTPP, Dholpur (CCPP)d) Nuclear: RAPS-A, RAPS-B3. Sources of Start-up powera) RPS HEP-Self start: 172 MWb) JS HEP- Self start: 99 MWc) Anta (Gas): 80 MWTotal: 351MW4. Requirement of Start-up power:a) Start-up at Kota STPS: 60 MWb. RAPS-A & RAPS-B: 50 MWc. Railway Traction: 70 MWd. Other Essential Loads: 171 MWTotal: 351 MW5. System Synchronization:After build-up of the Rajasthan Sub-system, it can be synchronized with thecombined North-Central (NC) and Eastern U.P Subsystems or only with North-Central Subsystem as per situation at the following possible connections.i) 400 kV Hissar-Bhiwadi at Hissar/Bhiwadiii) 400 kV Agra-Bassi at Agra/Bassiiii) 400 kV Ballabgarh-Bhiwadi at Ballabgarh/Bhiwadi6. The status of feeders, bus arrangement etc. at various 220 kV Grid substations will remain as mentioned in chapter 4 titled islanding schemes.3.3.2. Sequence for restoration of Rajasthan Sub-SystemAt the time of subsystem build up, the action to be taken at the major generatingstations/ grid substations is as given below:1. R.P.Sagar HEPi) R.P.Sagar HEP shall self-start the units and synchronize with Western Region(WR) supply on 132 kV R.P.Sagar-Gandhi Sagar line for stabilization.ii) In case of any problem in self-starting of units at R.P. Sagar, avail start-uppower from Gandhi Sagar (WR) and start the units at R.P.Sagar.iii) Extend start-up power or receive power from Jawahar Sagar as the case maybe.iv) Extend supply to Kota (S)2. Jawahar Sagar HEPJawahar Sagar HEP shall self start the units and extend power to RPS. In case ofproblem in self-starting the units, avail start-up Power from RPS and start-up itsunits.3. Kota (Sakatpura) 220 kV Grid Sub-Stationi) Avail power from Badod (WR) on 220 kV Badod-Kota circuit and start-uppower shall be extended to Kota STPS, RAPS-A and RAPS-B. Simultaneouslysynchronization with the supply from RPS shall also be carried out.ii) In case start-up power from Badod is not available, Kota (S) shall avail thepower from RPS and extend it to Kota (STPS), RAPS-A and RAPS-B.iii) Extend power supply for Railway Traction.iv) Synchronize with supply extended from survived RAPS-A /RAPS-B islands.v) Synchronise with supply extended from Anta or, in case request received fromAnta, start-up power / reference shall be extended from Kota (S) to Anta, inconsultation with SLDC Heerapura.vi) Extend supply to Jaipur for other essential load.4. Kota (STPS)i) Kota STPS to avail start-up power from Modak or from Kota (S).ii) Extend supply to Jaipur, in case of supply could not be extended to Jaipurthrough Kota (S).iii) If power is available at 400 kV GSS, Heerapura, then avail power from 400KV GSS, Heerapura.5. RAPS-A & RAPS-Bi) In case of survival of either of RAPS islands, extend supply to Kota (S) andsynchronise with Kota (S) once the supply around Kota (S) has been stabilized.ii) In case of tripping of RAPS-A, avail start-up power from Kota (S). In case ofnon-availability of power from Kota (S) / RP Sagar, RAPS(A) shall initiate actionto draw power from Western Grid by charging 132/220 kV, 50 MVA transformerat RAPS(A) through 132 kV Gandhi Sagar-RP Sagar II.iii) In case of tripping of RAPS-B. avail start-up power from Kota. (S). In case ofany problem in RAPS-B-Kota (S) ckt, the start-up power can be availed throughAnta/ RAPS(A)iv) In case RAPS-B survives, then, in consultation with SLDC control Room, itshall extend power to Anta through RAPS-B RAPS-C tie for starting of GTs/synchronization.6. Anta Gas Power Station (ANGPP)i) In case, Anta has survived on house load, extend supply to Kota (S) forsynchronization/build-up of system. Alternatively receive the supply from Kota(S) / RAPS-B, if 220 kV Kota (S) / RAPS-B buses are in charged condition. Thetwo supplies also to be synchronized at the earliest opportunity.ii) In case of tripping of units at Anta, self start GTs at Anta and extend supply toKota(S).iii) In case of any problem in self starting of units at Anta or extending supply toKota (S) request Kota (S) to extend supply and start GTs /synchronise.iv) Extend supply from Anta to Sawai-Madhopur, Dausa, Bharatpur and Hindaunfor Railway Traction load.7. Jaipur 220 kV Grid Sub-Stationi) Avail power supply from Kota (S)/Kota STPS.ii) Extend power to Dausa and Bharatpur for Railway Traction and otheremergency loads.iii) Extend power to Khetri for further extension to Suratgarh STPS as startuppower, in case there is delay in getting BBMB supply at Khetri.iv) Extend power to 400 kV Heerapura / Bassi substation for synchronization ofRajasthan Subsystem with North-Central (NC) Subsystem.8. Khetri 220 kV Sub-Stationi) Khetri shall get BBMB supply from Hissar and start up power shall beextended to Suratgarh STPS.ii) In case there is delay in getting BBMB supply then Khetri shall avail powerthrough Jaipur from Rajasthan Subsystem and extend it to Suratgarh STPS.9. Restoration of Suratgarh STPSSuratgarh Super Thermal Power Station (SSTPS) shall avail start-up power in thefollowing descending order of priority:Priority-1: From BBMB System through Bhakra (R)- Jamalpur- Sangrur-Hissar- Khetri- Ratangarh- Suratgarh STPS.Priority-2: From Rajasthan Subsystem through Kota (S)-Jaipur- Khetri-Ratangarh- Suratgarh.Priority-3: From Rajasthan Subsystem through Kota (S)-Jaipur- Reengus-Ratangarh- Suratgarh10. Dholpur CCPP(i) In case Dholpur CCPP has survived extend supply to Bharatpur/Hindaunfor railway traction load.(ii) In case of tripping of Dholpur CCPP, request Bharatpur to avail powerfrom Agra and extend to Dholpur and start/synchronise GT. (iii) Extend supply to Hindaun, Dausa & Jaipur.11. Giral LTPSGiral LTPS shall avail start- up power in the following descending order ofpriority:Priority 1 : From 220 kV GSS AmarsagarPriority 2 : From 220 kV GSS Barmer12 Ramgarh GTPPSelf start the units at Ramgarh and extend start up power to Giral LTPS throughAmarsagar.3.4 Caution while Restoration of Rajasthan Sub-SystemI. While restoring the Subsystem, the load generation balance is to be maintained.II. In case of survival of RAPS-A/RAPS-B islands, these must be synchronizedwith the supply of R.P Sagar / Kota (S) at the earliest opportunity.III. The power supply to Railway Traction and RAPS-A / RAPS-B is to beextended on top priority.IV. In case, Kota (S) has availed start-up power from Badod and RP Sagar hasbeen started up separately, then the two supplies are to be synchronized at Kota(S) / R.P. Sagar for stability and then the supply be extended further to otherstations.3.5. Synchronization of Rajasthan Sub-SystemRajasthan Sub System is to be synchronized with rest of the NR grid at thefollowing possible connections as indicated at 3.3 (5).3.6. Start-Up Stages and Sequencea. For different Restoration Stages in Rajasthan Subsystem, refer Annexure 3.1b. For detailed Start-up Sequence in Rajasthan Subsystem refer Annexure -3.23.7 General guidelines & precautions in system restorationThe general guidelines and precautions to be followed during system revival arementioned below:a. SLDC shall at all time have the latest amended copy of this documentavailable in the Control Room.b. The Shift Incharge, SLDC shall inform the Head of SLDC about the situationand request assistance in the restoration process.c. During total grid collapse/ failure of supply at the GSS, the In-charge of theshift will inform about grid failure to the XEN/ AEN In-charge of the GSS andalso to SLDC control room and wait for the instructions from SLDC controlroom. The shift In-charge will get all the incoming (if no power is available) &outgoing feeders including circuit breakers controlling main powertransformers opened immediately. On load tap changers (OLTCs) of thetransformers would be brought down to normal tap position by local manualcontrol. This should be completed within 10 minutes of the grid failureby each Shift duty In charge. The In-charge of the GSS shall reach theControl room as soon as the information regarding disturbance isconveyed to him.d. During total grid collapse/failure of supply at any power station the in-chargeof the shift will inform about grid failure to the incharge of the power stationand also to SLDC control room, Heerapura and wait for the instructions fromSLDC control room.e. During revival of the system, In-charge of sub stations, power stations andSLDC would remain present in control rooms of substations so as to expediterestoration of the system.f. In order to maintain a balance between load - generation at the time of gridcontingency the list of generating stations with black start facility, interstate/inter-regional ties, synchronizing points and essential loads to berestored on priority, should be prepared and updated regularly and must beavailable at all times in SLDC.g. While building up the system, it would be ensured that the voltage at thecharging end remains within limits. Before switching next section, essentialload of substation shall be connected to enable charging of battery, shuntreactor shall be connected and a small load may be switched on at each substation to ensure charging end voltage. However, the ultimate objective, viz.building up of the network should not be lost sight of, while connecting theloads and large loads shall not be switched on. If charging end voltage dipsat any substation, non-essential load or shunt reactor at intermediatestations may be switched off.h. Security of the network being built up would be strengthened at the earliestby closing the parallel lines available in the restoration path.i. Priority would be accorded for extending supplies to railway traction andinstallations where safety is of paramount importance such as nuclear powerstations. The list of priority load is given at Annexure 3.3j. All switching instructions for a particular system have to emanate from SLDC,Heerapura. For synchronization of two systems, NRLDC would be the coordinatingagency.k. In line with Clause 5.8(e) of IEGC, during system revival all communicationchannels required for restoration process shall be used for operationalcommunication only, till grid normalcy is restored.l. Synchronizing facility should be available at following grid substations so asto have maximum flexibility in choosing the point of synchronization.

m. Despite the urgency of the situation, careful and complete logging of allmessages and all operations is essential to facilitate subsequentinvestigation into the incident and the efficiency of the restoration process.3.8 Inter-regional supportIn case of disturbance or any other contingency in the northern region or any otherneighbouring region, NRLDC shall permit exchange of such power with theneighbouring region needed to meet the essential load, start-up-power, railwaytraction and other such emergent requirements for the duration of suchcontingencies.3.9 System Security AspectsWhile restoring the system, load generation balance is to be maintained in eachsubsystem and all efforts to be carried out by all the users to maintain theparameters within the subsystem near nominal values for security of operation of therestored subsystem as well as for ease of synchronisation.3.10 Power Supply to Railway Traction Substations from RajasthanSubsystemDetails of the existing Railway Traction Connections falling under Rajasthansubsystem are as under:a. Railway West Central.b. Section : i) Mathura-Kota-Mumbai ,c. Railway traction substation: Bharatpur, Bayana - Agra, Hindaun City,Gangapur city, Sawai Madhopur, Lakehri, Gurla & Ramganj Mandi.d. Max. Rly traction load : about 70 MWe. Feeding grid sub-stations: 220kV GSS at Kota (S), Hindaun BharatpurSawai Madhopur, Modak.

Chapter- 4Islanding Schemes4.1 OverviewThis is a system requirement under contingency conditions wherein thepower network is splitted into healthy and self-sustaining zones so thatcascade tripping of all generating stations in the entire region is avoided.As per the philosophy being followed in Northern Region, an attempt tokeep entire system integrated through adequate under frequency relays toshed load should be the first priority. Islanding schemes are the last resortand need to be confined to following two situations:(i) Sensitive generating stations such as nuclear power stations(ii) Sensitive/ strategic loadsAll efforts be made by the users to maintain the system parameters nearnominal values for security of operation of the restored subsystem as wellfor ease of synchronisation.4.2 Islanding Schemes4.2.1 In order to isolate and save healthy parts of the grid during anydisturbance, under frequency islanding schemes have to be designed anddeveloped based on system study and simulating the conditions requiringisolation of a generator from rest of the grid.4.2.2 SLDC shall make the islanding schemes in consultations with NRPC andshall modify as per system requirement.4.2.3 SLDC shall formulate one or more sets or subsets of islanding scheme(s)to prevent tripping of nuclear generating units operating within the state.Such schemes shall be formulated in consonance with the principles andguidelines decided by NRPC. NRLDC/SLDC shall effect changes to anysuch islanding scheme, as may be suggested by NRPC and NRLDC.These changes have to be informed to NRPC/NRLDC and all effectedusers as and when implemented.4.2.4 SLDC shall effect real time monitoring of difference between generationand load of the area covered by each islanded scheme in operation. Incase of large deviation, SLDC shall effect appropriate changes in areacovered by an islanding scheme by making operative or blocking thetripping of lines through respective under frequency relays. Thesechanges have to be informed to NRPC/NRLDC as and whenimplemented.4.2.5 The incharge of Grid Substations where under frequency relays forislanding purposes are installed shall confirm to SLDC through anumbered message, the status of UF relays which are blocked / madeoperative as per latest system conditions / changing loads. No alterationsin Under Frequency Relays (UFR) status/settings shall be made withoutspecific approval through a coded message from SLDC. .At the time ofchange in system status necessitating blocking / operating of these relays,the shift engineer of LD centre shall convey the changed requirement torespective GSS and obtain confirmation that the relay status has beensuitably changed. It has to be ensured that due permission is taken fromNRLDC in respect of any such tripping of inter-state lines and interconnectionwith ISTS.4.2.6 SLDC shall also have backup system of tripping such lines using directcircuit breaker control from SLDC.4.3 Existing Islanding Schemes4.3.1 RAPS Islanding SchemeRajasthan have two nuclear stations RAPS A and RAPS B with following capacities:Unit No.MW

RAPS-AUnit-I100 MW

Unit-II200 MW

Total300 MW

RAPS-BUnit-III220 MW

Unit-VI220 MW

Total440 MW

It is important that during any major Grid Disturbance in the Northern Region, the tripping of units of nuclear stations is prevented because of sensitive nature of such generating units. The islanding scheme for RAPS has been designed such that the generating units separate from the main Regional Grid and remain survived with islanded loads through intentional implementation of under frequency relays schemes. The frequency setting and time delay for Islanding and units coming to house loads are given in table below:

RAPS- ARAPS- B

FrequencyHz.Time DelaySec.FrequencyHz.Time DelaySec.

Islanding--47.75 seconds

47.5Instantaneous47.5Instantaneous

HouseLoading47.510 seconds47.55 seconds

47.1Instantaneous47.2Instantaneous

4.3.2 RAPS A IslandingA Single line diagram of this islanding Scheme is placed at Annexure- 4.1RAPS A islands at 47.5 Hz instantaneousThe following conditions are envisaged:1. When only one machine is generating at RAPS A, matching load will be provided by220 kV GSS Debari alone. Under this condition, 220 kV RAPS A Kota-I & III lines shall trip at 47.5 Hz (with Kota-II already connected to RAPS B). Thus Kota loads areautomatically disconnected from RAPS A.2. When both the machines of RAPS A are generating, matching load will be provided by220 kV GSS Debari, Dayra and part of 220 kV GSS Kota.3. When both the units of RAPS A are operating, the loads shall be regulated such thatDebari load is equal to Unit-II generation minus 15 MW and RAPS-A- Kota I load willmatch Unit-I generation minus 35 MW whereas if only one unit is operating the islandingload will match the generation minus 35 MW.4. In the event of load crash, when one machine is generating and load of Debari alone isin-sufficient to match the islanding load, then islanding load will be extended to part load ofKota (Trf. No.4) and load of Dayra.5. The following arrangements are to be kept at RAPS A, 220 kV GSSs of Debari,Sakatpura (Kota), Dayra and Banswara to ensure smooth functioning of the islandingscheme. The operating status of U/F relays like Block, Operative and Normally Openrequired to be kept for successful islanding has been also indicated below:AT RAPS A

The status of lines with setting of U/F Relays is kept as under:S. NoName of lineStatusSettings

1220 kV RAPS A- Kota-IOperative/ Blocked #47.5 Hz(Inst.)

2220 kV RAPS A- RAPS-BNormally Open-

3220 kV RAPS A- Kota-IIIOperative47.5 Hz(Inst.)

4220 kV RAPS A- DebariBlocked47.5 Hz(Inst.)

AT 220 KV GSS DEBARI1. 132 kV loads from Debari will be regulated through under frequency relay set at 47.5 Hzand the trippings shall be blocked/operative as per the load requirement.The status of lines with setting of U/F relays is kept as under.

S.NoName of lineStatusSetting

1220 kV Debari-RAPS ABlock47.5 Hz (Inst.)

2220 kV Debari RAPS BOperative47.7 Hz (Inst.)

3220 kV Debari ChittorOperative47.7 Hz (Inst.)

4220kV Debari BanswaraNo Relay-

5132 kV Debari SukherBlock/Operative #47.5 Hz (Inst.)

6132kVDebariMavli- DaribaBlock/Operative #47.5 Hz (Inst.)

7132 kV Debari-HZLBlock/Operative #47.5 Hz (Inst.)

8132 kV Debari-MadriNo Relay-

9132 kV Debari-NathdwaraLine-NormallyopenU/Frelay- Operative*47.5 Hz (Inst.)

10132 kV Debari-BhatewarLine-NormallyopenU/Frelay- Operative*47.5 Hz (Inst.)

AT 220 kV GSS BANSWARAUnder frequency relays on all incoming feeders from Mahi PH-I & Mahi PH-II, 132kV Banswara- Bagidora and 132 kV Banswara Pratapgarh feeders will be kept alwaysoperative. 132 kV Banswara Pratapgarh feeder will be kept normally open at Pratapgarh.The status of lines with setting of U/F relays is to be kept as under:-S.No.Name of lineStatusSetting

I132 kV Banswara- Mahi PH-I circuit I & IIOperative47.5Hz. (Instt.)

II132 kV Banswara- Mahi PH-II circuit I & IIOperative47.5Hz. (Instt.)

Iii132 kV Banswara- PratapgarhOperative47.5Hz. (Instt.)

Iv132 kV Banswara-BagidoraOperative47.5Hz. (Instt.)

AT 220 KV GSS KOTA (SAKATPURA)The following arrangements are being kept at 220 KV GSS Kota Sakatpura:-1. 220 kV Bus D is to be kept as dedicated for RAPS A Island. 220 kV Bus Couplerbetween A to D will be operative at under frequency setting of 47.5 Hz, so that Bus Dremains connected to RAPS A. 132 kV RPS-Kota Circuit (direct) will be kept on 132 kVBus of Transformer No. 4 connected to Bus D, which will provide RPS Hydel support tothe island, if required.2. 100 MVA Transformer No. 4 and 220 KV Dayra shall be always kept on Bus D.Transformer No. 4 will provide load of 132 kV Bundi, 132 kV Lakheri, 132 KV Gopal Mill,132/33 kV 20/25 MVA Transformer No. 1 and 2 for the Island. The U/F tripping on theseloads will be set at 47.5 Hz and shall be kept operative/blocked as per load requirement tobe monitored by L.D.3. 220 kV Kota (I)-RAPS A connected on Bus D will be Blocked/Operative at 47.5 Hz asper generation available at RAPS A.4. 220 kV Kota (III) -RAPS A will be on any Bus A, B or C with U/F relay operative at 47.5Hz.5. 220 kV RAPS B-Kota-II will also be on any Bus A, B or C with U/F relay operative at47.7 Hz.6. The synchronization of island may be done at RPS with MP Power on 132 kV GandhiSagar line-II or at Kota (S) with 220 kV Badod-Kota if required. MP power will be available through 220 kV Badod-Kota but this circuit will be normally open at Kota. In case of operation of 220 kV Badod-Kota lines as inter regional tie lines the same shall not be kept on Bus D at Kota (s).Status of lines with setting of U/F relays is to be kept as under:Status of lines with setting of U/F relays is to be kept as under:S. No.Name of lineStatusSetting

i)220 kV Kota-RAPS A Circuit-IBlock/Operative #47.5 Hz (Inst.)

ii)220 kV Kota-RAPS B Circuit-IIOperative47.7 Hz (Inst.)

iii)220 kV Kota-RAPS A Circuit- IIIOperative47.5 Hz (Inst.)

iv)220 kV Bus coupler betweenBUS A to DOperative47.5 Hz (Inst.)

v)132 kV Kota-BundiOperative/Block #47.5 Hz (Inst.)

vi)132 kV Kota LakheriOperative/Block #47.5 Hz (Inst.)

vii)132 kV Kota-RPS (Direct)Always Closed,NoU/FtobeProvided.-

viii)132/33 kV 20/25 MVA Trf. No.1Operative/Block #47.5 Hz (Inst.)

ix)132/33 kV 20/25 MVA Trf. No.2Operative/Block #47.5 Hz (Inst.)

x)132 kV Kota- Gopal MillOperative/Block #47.5 Hz (Inst.)

AT RPS Hydel P.S.1. One unit will be kept on main Bus B which is Islanding Bus and 3 units on 132 kV main Bus A. 132 kV Gandhi Sagar Circuit-II will be on Bus B and shall be kept normally open at RPS end. This may be utilized to further synchronise the Island with MP to stabilize theisland system, if required.2. 132 kV RPS-Kota (Direct ckt.) will also be on main Bus B included in the Island.3. 132 kV RPS-Bhilwara I & II and 132 kV RPS-Ind. Area Kota circuits will be on Bus A.The under frequency relay settings will be as under:-S.No.Name of lineStatusSetting

i132 kV Bus CouplerOperative47.5 Hz (Inst.)

ii132kVRPS- Bhilwara-I & IIOperative47.7 Hz (Inst.)

AT 220 KV DAYARAAll loads will be kept connected.4.3.3 RAPS B ISLANDINGA single line diagram of the scheme is placed at Annexure 4.2.1. Islanding shall take place at 47.7 Hz with 5 sec. delay or 47.5 Hz instantaneous. AtRAPS B the total generation of Unit-III & IV is expected to be around 400 MW. RAPSBmachines will be islanded with matching load of 180-200 MW. This load is to beprovided normally from 220 KV GSSs Chittor, Nimbahera & Bhilwara. In case of lowload conditions, the islanding load will have to be extended to Bali and further to 220 kVGSS Pindwara.2. Presently, no Under Frequency Relays are required for 220 kV Chittor-Nimbahera lineand 220 kV RAPS B Chittor (Chittor end) on both the circuits. Loads of 132 kV GSSHamirgarh, Sawa, M/s Aditya Cement, M/s BCW, M/s CCW & M/s HZL, if not injectingpower, shall be fed from 220 kV Chittorgarh.3. The operating status of UFR relay like Block, Operative and Normally Open required tobe kept for successful islanding has also been indicated.4. The settings of under frequency relays in the above Island are to be kept as under:AT RAPS B ENDS.No.Name of lineStatusSetting.

i)220 kV RAPS B-Kota-IIOperative47.7 Hz(5 Sec.)

ii)220 kV RAPS B-Kota-IIOperative47.5 Hz (Inst.)

iii)220 kV RAPS B-DebariOperative47.7 Hz(5 Sec.)

iv)220 kV RAPS B-DebariOperative47.5 Hz (Inst.)

v)220 kV RAPS B Chittor-I & IIBlock47.7 Hz(5 Sec.)

vi)220 kV RAPS B-AntaOperative47.7 Hz(5 Sec.)

vii)220 kV RAPS B AntaOperative47.5 Hz (Inst.)

viii)220 kV RAPS B-RAPS A Tie line.NormallyOpen-

AT 220 KV GSS CHITTORGARHThe U/F Relays of 220 kV Chittorgarh-Bhilwara (both ends) will be made operative by LD if the requirement of load is indicated by RAPS authorities to be around 100- 120 MW (oneunit), otherwise this relay will be kept blocked so as to provide islanding load of 180-200MW.S.No.Name of lineStatusSetting

i.220 kV Chittorgarh-BhilwaraNormallyBlock47.7 Hz (Inst.)

ii220 kV Chittorgarh-DebariOperative47.7 Hz (Inst.)

iii132 kv Chittor HZLOperative47.7 Hz (Inst.)

AT 220 kV GSS DEBARI

S.No.Name of lineStatusSetting

I.220 kV Debari-RAPS BOperative47.7 Hz (Inst.)

ii.220 kV Debari-ChittorgarhOperative47.7 Hz (Inst.)

iii.220 kV Debari- RAPS ANormally block47.5 Hz (Inst.)

AT 220 kV GSS SAKATPURA KOTAThe under frequency relay on 220 kV Kota-RAPS B (II circuit) which will normallyremain on Bus C, will be set at 47.7 Hz (Inst.) and will remain operative. AT 220 kV GSS NIMBAHERALoads of 132 kV Bhatewar, Bhinder, Mangalwad, Chhoti Sadri and Pratapgarh shallbe fed from Nimbahera and shall not be transferred to other GSSs without approval ofSE(SO&LD). 132 kV loads from Nimbahera will be regulated through under frequency relay set at 47.7 Hz. (Instt.) and the trippings shall be blocked/ operative as per loadrequirement.The status of feeders with setting of U/F relay to be kept as under :

S.No.Name of feederStatusSetting

1132 kV MangalwadOperative / Block #47.7 Hz (Inst.)

2132 kV Chhoti SadriOperative / Block #47.7 Hz (Inst.)

AT 220 kV GSS BHILWARABus arrangement on 220 kV side will be as under:On 220 kV Main Bus (A+D).220 kV Bhilwara-Kota-I220 kV Bhilwara-Kota-II220 kV Bhilwara-Kankroli-Sirohi220 kV Bhilwara-Anta-I220 kV Bhilwara-Anta-II220 kV Bhilwara-Beawar220 kV Bhilwara-PaliOn 220 kV Main Bus (B+C) (Islanding bus).220 kV Side of 220/132 kV, 100 MVA Transformer No.1.220 kV Side of 220/132 kV 100 MVA Transformer No.2220 kV Bhilwara-Chittorgarh220 kV Bhilwara-BaliThe status of lines with setting of under frequency relay (s) to be kept as under :-

S.No.Name of lineStatusSetting

(i)220 kV Bus Coupler A to BOperative47.7 Hz (Inst.)

(ii)220 kV Bhilwara Bali.Operative/Block #47.7 Hz (Inst.)

(iii)132 kV Bhilwara- KharchiOperative/Block #47.7 Hz (Inst.)

(iv)132 kV Bhilwara RaylaOperative/Block #47.7 Hz (Inst.)

(v)132 kV Bhilwara GangapurOperative/Block #47.7 Hz (Inst.)

(vi)132 kV Bhilwara HamirgarhLine-Normallyopen U/f relay operative47.7 Hz (Inst.)

(vii)132 kV Bhilwara-MandalgarhOperative/Block #47.7 Hz (Inst.)

AT 220 KV GSS BALI132 kV Pali-Falna will remain normally open at Pali end.The status of lines with setting of U/F relay to be kept as under :-

S.No.Name of lineStatussetting

(i)220 kV Bali-BhilwaraOperative / Block #47.7 Hz ( Inst.)

(ii)220 Kv-Bali SirohiOperative47.7 Hz ( Inst.)

(iii)220 kV Bali-PindwaraOperative/Block #47.7 Hz ( Inst.)

(iv)132 kV Bali-SumerpurOperative / Block #47.7 Hz ( Inst.)

(v)132 kV Bali-FalnaOperative / Block #47.7 Hz ( Inst.)

(vi)132 kV Bali-RaniOperative / Block #47.7 Hz ( Inst.)

AT 220 KV GSS PINDWARA132kV Abu Road will be fed from Pindwara and 132 kV Abu Road- Reodar willremain normally open at Abu Road GSS.The status of lines with setting of U/F relay to be kept as under :-S.No.Name of lineStatusSetting

(i)220 kV Pindwara BaliOperative / Block #47.7 Hz ( Inst.)

(ii)132 kV Pindwara DebariLine-NormallyopenU/f relay operative47.7 Hz ( Inst.)

(iii)132kVPindwaraSirohi(Both circuits )Line-NormallyopenU/f relay operative47.7 Hz ( Inst.)

(iv)132kVPindwaraAbuRoadOperative/Block #47.7 Hz ( Inst.)

AT 220 KV GSS SIROHI132 kV Sumerpur-Sirohi will remain normally open at Sumperpur end.The status of lines with setting of U/F relay to be kept as under ;-S.No.Name of lineStatusSetting

(i)220 kV Sirohi - BaliOperative47.7 Hz ( Inst.)

(ii)132 kV Sirohi-SumerpurLine-Normallyopen U/f relay operative47.7 Hz ( Inst.)

AT RPS POWER STATION132 kV RPS-Bhilwara-I & II will be connected on Bus A as indicated for RAPS-A isalnding.i).132 kV RPS Bus Coupler A-BOperative47.5 Hz (Inst.)

ii).132 kV RPS-Bhilwara-I & IIOperative47.7 Hz (Inst.)

4.4 Caution in islanding process1. RAPS- B shall be synchronised at 220 kV Kota (s) GSS or Anta Gas Power Station.2. One machine of 43 MW will start generation at RPS when frequency falls below 48.0 Hz,if required it shall run on condenser mode till system stabilised.3. Start up power from island shall be extended to 220 kV GSS Kota (S), Anta and JSPower Station.4. Island will be extended in phases as per system restoration procedure.5. On request from RAPS B, UFR of 220 kV Chitttor Bhilwara will be made operativewhen generation at RAPS B is low (100 120 MW). Otherwise UFR will be blocked toprovide upto 200 MW islanding load.6. While restoring the system, load generation balance is to be maintained in eachsubsystem and all efforts to be carried out by all the constituent to maintain the parameterswithin the subsystem near nominal values for security of operation of the restoredsubsystem as well for ease of synchronization.7. The power system operation is a dynamic situation, the SLDC shall keep on monitoringthe system status at least once in every shift and ensure that status of UFRs be keptsuitably operative / blocked with correct settings as per system requirements, so that in theevent of major grid disturbance, Islanding takes place smoothly.* The feeder will remain open under normal grid conditions, whereas the UFR for the saidfeeder will always remain operative. However, in the event of transmission constraint, thefeeder may have to be closed to cater the load requirement of a particular area but theUFR will continue to be always operative# To be made operative/blocked by L.D. as per generation/load pattern.4.5 Islanding Scheme ReviewExisting islanding scheme described at 4.3 above relates to current system conditions andparameters. The frequency settings of Under Frequency Relays, Blockage/operation andtime settings etc. needs to be checked and adjusted from time to time based on changedsystem conditions and configuration.

Chapter 5Demand Estimation and Control5.1 Overview5.1.1 Demand estimation plays a very important role in system operation. In thelong term, it constitutes important input for generation and transmissionnetwork planning. In the medium term, say one year, it constitutes animportant input for outage planning of generating units and transmissionlines and short term bilateral agreements for power purchase. In the shortterm, it is an important input for generation and drawal scheduling, loadshedding & bilateral power purchase agreements. Variation in demand inreal time operation from the estimated values could either be absorbed bythe grid or affect it adversely. Even if the estimates are accurate, thegeneration could vary from scheduled values adversely affecting the grid.Demand control thus play an important role in arresting these adverseeffects on the grid5.1.2 Demand estimation and control is essentially the responsibility of SLDCsand NRLDC would generally not have a major role in this area. NRLDCwould give instructions to SLDCs on demand control whenever the samehas a bearing on the security of the regional grid & such instructionswould have to be complied forthwith by all SLDCs.5.2 Demand estimation5.2.1 SLDC shall be responsible for assessing the availability and requirementin kW, kWH & kVAr for one year on monthly basis.The SLDCs wouldforecast demand (MW peak & energy in MWh) on an annual, quarterly,monthly, weekly and ultimately on daily basis, which would be used in theday-ahead scheduling. SLDC will maintain a historical database for thepurpose and be equipped with the state-of-the-art tools such as EnergyManagement System (EMS) for demand forecasting. Ideally, the forecastsshould be on hourly basis (8760, 720 & 168 values respectively in theannual, monthly and weekly forecasts) rather than mentioning only thepeak MW and energy requirements for the period.5.2.2 Discoms shall submit its power requirement to SLDC for the ensuing yearby 31st October on monthly basis as per their entitlement and share ingenerating stations and contract signed with the generating companiesand the traders5.2.3 Discoms shall provide to SLDC estimates of load that may be shed whenrequired, in discrete blocks with the details of arrangements of such loadshedding.5.2.4 Discoms shall also furnish realistic category-wise demand and energyrequirement for their respective companies along with details of essentialloads, supply hours to be maintained in rural areas, details of power cutsimposed or to be imposed and specific requirements, if any.5.2.5 The above demand estimation covers only active power. It is alsoimportant that, the reactive power requirements are also forecasted rightfrom substation level by each SLDC. The reactive power planningexercise and programme for installation of reactive compensationequipments should take care of these requirements also and would becarried out by STU in consultation with NRPC and Discoms.5.2.6 The SLDC would forecast the demand (in MW as well as MWh) onquarterly, monthly, weekly and ultimately on daily basis on the basis ofrequirement received from Discoms, which would be used in the dayaheadscheduling of Rajasthan as a whole.5.2.7 Attention shall also be paid by SLDC in demand forecasting for specialdays such as important festivals and National Holidays having differentcrests and troughs in the daily load-curve as compared to normal weatherconditions & days, The Discoms may negotiate short term & spot powerpurchase as per their requirement.5.2.8 SLDC shall furnish data for and participate in deliberations of loadgeneration balance, Annual Demand, availability and shunt capacitorsrequirement studies of NRPC. It shall take into consideration their reportsfor demand estimation.5.3 Demand control5.3.1 Primarily the need for demand control would arise on account of thefollowing conditions:- Variations in demand from the estimated or forecasted values, whichcannot be absorbed by the grid, and Unforeseen generation / transmission outages resulting in reduced poweravailability, and Heavy reactive power demand causing low voltages, and Commercial reasons.5.3.2 SLDC shall match the consolidated demand with the consolidatedgeneration availability from SGS, ISGS, IPP/CPP and other sources andshall exercise the Demand Control such that there is a balance betweenthe energy availability and the Discoms demand plus losses plus therequired reserve.5.3.3 As per section 6.4.8 of the IEGC, the SLDC shall regularly carryout thenecessary exercises regarding short-term demand estimation to plan inadvance as to how the load would be met without overdrawing from thegrid. The following deviations from the schedule and other violations wouldbe controlled by the SLDC. Over drawls/ under injection at frequencies below 49.2 Hz. Under drawls/ over injection at frequencies above 50.3 Hz. Reactive power drawls/injections causing low/high voltage respectively.5.3.4 If the demand estimation and generation availability figures published bythe SLDC indicate a significant shortfall or demand gap, in any Discomthen that Discom shall work out a plan to meet the shortfall. If the shortfallis not met out, a manual load shedding program shall be announced bythe Discom well in advance.5.3.5 SLDC shall advice the STU to plan Automatic Load Shedding Schemesand rotational load shedding by installing Under Frequency Relays.5.3.6 The guidelines for under frequency load shedding shall be prepared by theTechnical Committee, and approved by the SPC. A copy of the approvedguidelines can be made available on demand and on payment as may bedecided by the SPC.5.3.7 The details of feeders or group of feeders at a particular EHV sub-stationscheduled to be tripped through under-frequency load shedding schemewhether manually or automatic on rotational basis or otherwise shall bedisplayed on the Notice Board and at the sub-station for the information ofconsumer(s).5.3.8 NRPC Secretariat formulates under frequency load shedding scheme forthe Northern Region in consultation with all the constituents and NRLDC.The scheme considers the largest single credible contingency occurring inthe system and load shedding is based on tripping by fixed underfrequency as well as fixed frequency and rate of change of frequencyrelays.5.3.9 Demand control so exercised under these conditions by the SLDC, couldbe done manually or through the under frequency relays including thoseworking on rotational / sequential basis or through direct circuit breakertripping effected from SLDC/ Sub LDC using RTUs on under frequencydetection by SLDC/Sub-LDC computer or through telephonic instructions.5.3.10 Each user shall endeavour to restrict their drawl within their drawlschedule or entitlement whenever the system frequency is below 49.5 Hz.When the frequency falls below 49.2 Hz. requisite load shedding (manual)shall be done by the concerned Discom/user to curtail the over- drawl.5.3.11 During the demand control by manual disconnection of loads bystaggering among different groups, the changeover from one group toanother shall be carried out in a gradual and scientific manner so as toavoid excursions in the system parameters.5.3.12 The SLDC would also identify feeders drawing heavy quantum of reactivepower and disconnect the same under low voltage conditions. Necessarymetering arrangements/transducers for identifying such feeders shall beprovided by the RVPN.5.3.13 Sudden reduction in generator output by more than one hundred (100)MW unless under an emergency condition or to prevent an imminentdamage to the equipment, shall be avoided, particularly when frequency isfalling below 49.2Hz.5.3.14 Sudden increase in load by more than 100 MW by any SLDC, particularlywhen frequency is falling below 49.2Hz and reduction in load by suchquantum when frequency is rising above 50.3 Hz. Shall be avoided.5.3.15 No demand shed by operation of under frequency relays shall be restoredwithout specific directions from SLDC.5.4 Load CrashIn the event of load crash in the system due to weather disturbance or anyother reasons, the situation would be controlled by the SLDC by thefollowing methods :(i) Back down or close down of generating units of SGS exceptCPP & non conventional sources commensurate with systemfrequency & transmission constraints by giving SLDC Code.(ii) Lifting of the load restrictions, if any.While implementing the above, it shall be ensured that the provisions infrequency control under clause 6.8 shall not be violated. Further, in caseof Hydel generation linked with irrigation requirements, the actual backdown or close down of such Hydel units shall be subject to limitations onsuch account & to avoid spillage of water.

Chapter -6Network Security and System Operation6.1 System Operation6.1.1 The system has to be continuously operated as per the Security Standardsand criteria covered in the Indian Electricity Grid Code (IEGC), or inREGC. The switching operations, whether manual or automatic, shallbe based on the guidelines issued by(a) IEGC.(b) NRLDC's instructions/guidelines under Electricity Act, 2003.(c) REGC.(d) RERC's directives.(e) State Government's directives.(f) SPC's decisions.(g) SLDCs instruction and guidelines.6.1.2 No part of the STS shall be deliberately isolated from the integrated GRID,except(i) under an emergency, and under the conditions where the isolationwould prevent the total Grid collapse and/or enables early restorationof power supply,(ii) where serious damage to a costly equipment or personnel safety isimminent, prevented by such isolation.(iii) where such isolation is specifically advised by SLDC and(iv) Operating an under frequency/islanding scheme dully approved byTechnical Committee of SPC and as per directives of NRPC.All isolations shall be as per standing guidelines or be ratified by the SPC.Complete synchronization of integrated Grid shall be restored at theearliest.The restoration process shall be supervised as per procedure of themanual or as directed by SLDC.6.1.3 The 132KV & above rated transmission elements shall not be deliberatelyopened or removed from service without prior clearance of SLDC. Whereprior clearance from SLDC is not possible it shall be intimated to SLDCimmediately after the incident. Any emergency tripping not advised orpermitted by SLDC shall be reported to the SPC for needful in the nextmeeting.6.2 Special Care Areas:(i) Stations where Bus bar protection scheme is operative, it shall beensured that segregation of feeders on each bus are uniform. In case asubstation is interconnected with more than one source/ interconnectinglines, then it shall be ensured that these are connected on different busesto minimise the impact of break down or bus bar protection tripping.(ii) In the cases where Main-I and Main-II bus arrangements are available,the changeover of the feeders/ transformer from one bus to the otherwould be carried out uninterruptedly, wherever PTs are installed on all thefeeders. To avoid inadvertent tripping of bus-coupler on earth fault (E/F)due to contact resistance or opening time of different poles of the isolatorsbeing different, the tripping of bus couplers on earth fault would beblocked during changeover.(iii) At 400 kV sub-station which is having a breaker and a half scheme, itshall be ensured that the two buses remain connected at least by twoparallel paths so that any line / bus fault does not result in inadvertentmultiple outages. In case any element, say a line or an ILT, is expected toremain out for a period say beyond eight hours, the main and tiebreakersof such elements shall be closed after opening the line side isolator. Thisshould be done after taking all suitable precautions to avoid inadvertenttripping.(iv) The substation operators shall ensure the above condition even whenany lightly loaded line is opened to control over voltage as opening oflines, superimposed over other line outages (on account of faults createdby adverse weather conditions), may result in reduced security of thesystem. Opening a unloaded long line under high voltage conditions tocontrol high voltage shall be invariably avoided(v) Single pole auto-reclose facility on 400 kV lines shall always be inservice. NRLDCs approval would be obtained for taking this facility out ofservice.vi) All users would endeavour to operate the connected generation andreactive power management devices such as Synchronous Condensers,Static Var Compensators (SVCs) etc in a manner which enables stablevoltage behaviour at various points of the grid under different operatingconditions.vii) In line with section 5.2 (e) to 5.2(g) of the IEGC, the generating unitsshould be on free governor operation.6.3 Under Frequency Load Shedding SchemeThe SLDC would review under frequency load shedding scheme of NRPCand formulate the scheme in detail as per requirements of NRPC andupdate such scheme as per system requirement. From the viewpoint ofsystem security, it shall ensure that there would be no overlappingbetween areas covered by under frequency relay load shedding andthose covered by the manual load shedding plan as part of demandcontrol. SLDC would ensure that the automatic load relief through underfrequency relays would be available to the system under low frequencyconditions. Effectiveness of the scheme would be monitored periodicallyby SLDC and also by NRLDC/ NRPC in line with clause 5.2(m) of theIEGC. The same shall be monitored in the meetings of State levelTechnical Committee and also in the Operation Co-ordination Committee(OCC) of NRPC.STU / Discoms shall ensure that the feeders connected on UFRs areexempted from manual load shedding ensuring that the relief throughUFRs is available at all times.The guidelines for under frequency load shedding shall be prepared by theTechnical Committee and approved by the State Power Committee interms of clause No.9.3 of REGC. The copy of guidelines can be madeavailable on demand and on payment as decided by SPCThe particulars of feeders or group of feeders at a sub-station which shallbe tripped under under-frequency load shedding scheme whethermanually or automatic on rotational basis or otherwise shall be placed onNotice board and will also be available at the GSS for information of theconsumers(s).The Technical Committee shall deliberate and prepare the UnderFrequency Load Shedding Schemes at various sub-stations to ensure thatthe frequent tripping of same feeder is avoided.6.4 Protection Schemes6.4.1 Islanding schemeThe islanding schemes for RAPS-A and RAPS-B are in operation asdetailed in Chapter 4. SLDC shall ensure that load-generation balance ofeach islanding scheme is maintained continuously.SLDC shall monitor & follow-up the procurement and installation of UnderFrequency relays, any other Relays & apparatus of RVPN required forunder frequency load shedding and system islanding. It shall also takesteps to modify the settings as and when required. The scheme withmodifications shall be circulated periodically to all utilities.6.4.2 Special Protection schemeSTU shall formulate special protection schemes in consultation &coordination with generating companies and SLDC for the followingcontingencies:-i) Loss of generation at generating stations in the state having installedcapacity of 800 MW or above, as per direction from NRPC and also toensure that in the event of tripping of transmission line, cascaded trippingof generating units / transmission lines is avoided automatically.ii) Under voltage load shedding ( UVLS ) scheme to avoid voltagecollapse for designated 400/220 kV Grid Sub-Stations whenever thevoltage at a node drops below 380 kV for 400 kV level and 209 kV for220 kV level as per directions of NRPC.6.5 Recording Instruments and communication facilitiesGenerating Units having capacity of 200 MW and above, sub-stations withoperating voltage of 400 kV & above and 220 kV sub-stations with220/132 kV transformation capacity above 250 MVA shall have theDisturbance Recorders (DRs) and Event Loggers (ELs) fully functional.The DRs/ ELs shall have the time stamping feature of events upto theaccuracy of 1 millisecond, independent of scan rate and accuracy of DRsClock, and shall be capable of time synchronization using GPS timereference.All the recording instruments, SCADA system, Disturbance Recorders etc.available at each Station and state/sub-Load Despatch Centers shall bekept in good working condition. Adequate and reliable communicationfacilities shall be maintained with NRLDC, sub load despatch Centres andall EHV stations in the grid.6.6 System Management & ControlThe Grid discipline requires that SLDC, RVPN , Discoms and other usersmake all possible efforts to maintain grid frequency within the normal bandof 49.2 to 50.3 Hz or within the band as per latest revision in IEGC. Thiswould be ensured by adhering to the following steps:(i) Each generating station of RVUN shall provide to SLDC their estimatesof monthly availability on the year ahead basis for the next financial yearby end of October each year. Each station shall also provide to SLDCdaily availability for the month ahead by end of 25th day for the nextmonth.(ii) The SLDC shall regulate the load and generation of Discoms and SGSso that state may not draw more than its schedule during low frequencyconditions and less than schedule during high frequency conditions. (iii) The SLDC shall ensure that each of Generating Stations of SGS shallmaintain its generation schedule during low frequency conditions and notmore than its generation schedule during high frequency conditions.(iv) In case of low system demand from Discoms during normal systemoperations, generating units can be backed down/shut down, in order ofmerit, if so required by SLDC for optimum utilisation of availableentitlements. Wherever the State is likely to face power shortage situationdespite requisitioning its full entitlement from Central Sector, Discomswould be advised by SLDC to shed loads.(v) Discoms shall endeavor to enter into a bilateral agreement withconstituents of any region/ IPPs/ CPPs/ generating company/ tradinglicensees on long term basis, short term basis, day ahead basis and realtime basis and intimate SLDC.(vi) In any case, during low frequency conditions (below 49.2 Hz), noover drawls shall be affected.(vii) Except under an emergency condition or to prevent an imminentdamage to the equipment, sudden reduction in generator output by morethan 40% of capacity of each generating unit or one hundred (100) MWshall not be permitted by SLDC and shall be avoided by power stationoperator, particularly when frequency is below 49.2 Hz.(viii) Sudden increase in load by more than 100 MW, particularly whenfrequency is falling below 49.2 Hz and reduction in load by such quantumwhen frequency is rising above 50.3 Hz. shall not be permitted by SLDCand shall be avoided by the EHV substation operator.6.7 Preventive measures during high frequency conditions and duringlow frequency:(i) While the grid frequency is higher than 50.3 Hz, the MW generation atno generating station (irrespective of type and ownership) shall beincreased.(ii) In case, frequency has risen from a previous lower level to 50.3 Hz. orhigher, and due to normal governor action, the MW output of a generatingunit has fallen to a level requiring oil support or which results in unstableoperation of the unit, then MW output will be increased by operator to alevel, such that no oil support is required, and the unit can operate in astable and safe manner. The event shall invariably be reported to SLDC.(iii)The SLDC shift in charge shall ensure that when the frequency ishigher than 50.3 Hz, the actual net injection shall not exceed thescheduled dispatch for that time block. Also, while the frequency is aboveLast Updated : 30-06-2009- 43 -50.3 Hz, the SGS may (at their discretion) back down without waiting foran advise from SLDC to restrict the frequency rise. When the frequencyfalls below 49.5 Hz, the generation at all SGS (except those on peakingduty) shall be maximized, at least up to the level which can be sustained,without waiting for an advise from SLDC.(iv) No generating unit shall be synchronised with the grid while thegrid frequency is above 50.3 Hz. or higher, except with the specificconcurrence of NRLDC/ SLDC. This will not apply in case of nuclearunits, which may have to be re-synchronised to prevent poisoning out ofthe reactor. Frequency linked despatch guidelines issued by NRLDC willbe followed by each power station.(iv) SGS shall comply with the instructions of SLDC for backing down orpicking-up additional generation not detrimental to generating unit (i.e.ramp-up/ramp-down rate as specified by generating unit supplier /RVUN).Any non-compliance will be referred to Commission.6.8 VAR ExchangeThe SLDC shall take action in regard to VAR exchange with the northerngrid, keeping in view the voltage profile at the exchange points. It shallendeavour that local VAR compensation at each substation is soregulated that the VAR drawl at exchange point when the voltage at thatpoint is below nominal value is minimum and VARs are not injected whenthe voltage at exchange point is above the nominal value. Discoms shallensure that their VARs drawls are maintained as per the directives ofRERC.6.9 VAR Generation / Absorption by Generating UnitsIn order to improve the overall voltage profile, the generators shall run in amanner so as to have counter balancing action corresponding to low / highgrid voltage and to bring the system voltage towards the nominal value. Inorder to achieve the same, all generators shall generate reactive powerduring low voltage conditions and absorb reactive power during highvoltage conditions as per the capability limits of the respectivegenerating units. The On-Load Tap Changers (OLTCs) -on the generatortransformers wherever available, shall also be used to achieve this. Offload tap changers shall be so set as to take care of seasonal variations inthe voltage profile. SGS shall make available to SLDC the updatecapability curves for all the generating units indicating any restrictions, toenable accurate system studies and effective operation of system.6.9.1 Transformer tapsThe transformer tap position may alter reactive power flow so any changewill be effected only on the instruction from SLDC. In respect oftransformers declared as important elements of Regional Grid by NRLDC,NRLDC shall advise SLDC, the settings of transformer tap positions.SLDC shall carry out any change in tap positions of such transformersonly on advice of or after consultation with NRLDC. The tap position ofthe important generator transformers of SGS in Rajasthan Sub Systemshall be advised by SLDC based on system studies.6.10 Voltage Control at Grid Substations / Generating Stations6.10.1 In the event of high system voltage i.e. voltage going beyond upperpermissible limit (e.g., 400 kV Bus voltage going above 410 kV and 220kV bus voltages going above 245 kV), the following specific steps wouldbe taken by the respective grid substations / generating station at theirown, unless specifically instructed otherwise by SLDC: The bus reactors will be switched in. The manually switchable shunt capacitor banks shall be taken out. The switchable line/ tertiary reactors be taken in. Synchronous condensers shall be operated for VAR absorption. Hydel generators shall be operated as synchronous condenserwherever feasible for VAR absorption, with the consent of SLDC. Lightly loaded EHV lines shall be opened keeping in view the securityof the balance network with the consent of SLDC for 220 kV in NRLDCthrough SLDC for 400 kV.6.10.2 In the event of low system voltage, i.e. voltage going below lowerpermissible limit (e.g., 400 kV bus voltage going below 390 kV and 220 kVbus voltages going below 200 kV), the following specific steps shall betaken by the respective grid substations / generating stations at their own,unless specifically instructed otherwise by SLDC: The bus reactors (if ON) shall be switched out. The shunt capacitor banks will be switched in. The switchable line/ tertiary reactors be taken out. Synchronous condensers shall be operated for VAR generation Hydel generators shall be operated as synchronousCondenser for VAR generation wherever feasible with the consent ofSLDC EHV lines, which were opened to control high voltage or otherwise,shall be switched on with the consent of SLDC.6.11 Load management for controlling the voltageSLDC shall identify the radial feeders which have significant reactivedrawals and which can be disconnected in order to improve the voltageconditions in the event of voltage dropping to low levels. The details of allsuch feeders shall be kept handy in the respective control rooms andstanding instruction shall be issued to the operating personnel to obtainthe requisite relief in the hour of crisis by disconnecting such feeders onequitable and rotational basis.6.12 Regulatory measures by SLDC to prevent voltage collapseIn case the Discoms do not take the requisite measures by regulating theirVAR drawls and the system voltage drops down to low levels (say below120 kV at 132 kV bus), then SLDC may resort to regulatory measures byopening of tie lines including those, feeding radial loads in the areas ofdefaulting Discoms. While taking such action, SLDC would duly considerthat the same does not adversely affect the evacuation system fromexisting generation, voltage profile and system security.6.13 Switching-off of the lines in case of high voltageIn the event of persistent high voltage conditions when all other reactivecontrol measures as mentioned earlier have been exhausted, selected132 KV or 220 kV lines shall be opened for voltage control measures. Theopening of lines and in such an event reviving them back would be carriedout as per the instructions issued by SLDC in real time and as per thestanding instructions issued by SLDC from time to time. While taking suchaction, SLDC would duly consider that the same does not lead toconstraints in evacuation of generated power and adversely affect voltageprofile & system security.6.14 Line loadingIn accomplishing the frequency & voltage control measures outlinedabove, the shift incharge would take into consideration the thermal loadinglimits, surge impedance loadings and the loading permitted from stabilityconsiderations for each line. The shift incharge at SLDC or substationswould endeavour to keep the line / ILT loadings within limits and takecorrective action in case of overloading of any element. Special emphasiswould be laid by the system operator on identifying credible systemcontingencies & continuously evaluating the system under his controlagainst these contingencies.6.15 Operating manpowerThe control rooms of the SLDC, power plants, grid substations as well asany other control centers of RVPN shall be manned round the clock byqualified and adequately trained manpower who would remain vigilant andcooperative at all the times with SLDC so as to maintain the system safetyand security and operate it in a most optimum manner.6.16 System StudiesPreventive measures to control frequency and voltage detailed aboveshall be based on planning studies conducted by RVPN and operationalstudies conducted by SLDC. Operational studies by SLDC shall be basedon actual system conditions, preferably on real time data extracted fromSCADA, with appropriate corrections for errors to achieve convergence.6.17 Recording of Messages6.17.1 SLDC shall ensure that the entries in the log books must be madeimmediately after the conversation. Each person in the Control Room whois giving instructions, may note down the time and instructions andtransfer them immediately into the log book. Such entries would not be leftto be done at later stage. This practice shall be followed meticulously toavoid inaccuracies in the messages actually given and those recorded inthe SLDC6.17.2 The SLDC is maintaining a voice recorder system for recording andstoring in all messages, conversation and exchange of information throughtelephone between SLDC and NRLDC.6.17.3 The operational messages shall be given by the shift engineer (LD) to theshift engineer (EHV stations/ generating stations) with specific referenceto the equipment to be operated, in a sequential manner.

Chapter- 7Outage Planning7.1 Overview7.1.1 The preventive and capital maintenance of system is essential to maintainoptimum availability/efficiency levels. Such maintenance has to beplanned