Evolution of transmission sector in India, Regional and National Grid, Market structure, Transmission & Substation capacity, Distribution system in India

1. Power Transmission & Distribution in India
Industry Information Insights 2014

2. Table of Contents
Introduction
Regional and National Grid
Market Structure
Evolution of Transmission Sector
T&D Lines Length
Transmission Capacity
Substation Capacity
Distribution System
Competitive Bidding

3. Introduction
Thehugeamountofpowergeneratedinapowerstationistobetransportedoveralongdistancetoloadcenterstocaterpowertoconsumerswiththehelpoftransmissionlineandtransmissiontowers.
Forinstance,forapowerstationgenerating120MWpowerat10kVlinetolinevoltage, currentinthetransmissionlinewillbe8660A.Insteadofchoosing10kVtransmissionvoltage,iftransmissionvoltagewerechosentobe400kV,currentvalueinthelinewouldhavebeenonly261.5A.
So,thesectionalareaofthetransmissionline(copperconductor)willnowbemuchsmallercomparedto10kVtransmissionvoltage.Thecostofconductorwillbegreatlyreducedifpoweristransmittedathigherandhighertransmissionvoltage.
Thecostofconductorwillbegreatlyreducedifpoweristransmittedathigherandhighertransmissionvoltage.

4. Theuseofhighervoltage(hencelowercurrentintheline)reducesvoltagedropinthelineresistanceandreactance.Alsotransmissionlossesarereduced.
Standardtransmissionvoltagesusedare132kVor220kVor400kVor765kVdependinguponhowlongthetransmissionlinesare.
Afterthegenerator,thereisastepuptransformertochangethegeneratedvoltage(say10kV) todesiredtransmissionvoltage(say400kV)beforetransmittingitoveralongdistancewiththehelpoftransmissionlinessupportedatregularintervalsbytransmissiontowers.
Whilemagnitudeofcurrentdecidesthecostofcopper,levelofvoltagedecidesthecostofinsulators.Theideais,inaspreetoreducethecostofcopperonecannotindefinitelyincreasetheleveloftransmissionvoltageascostofinsulatorswilloffsetthereductioncoppercost.

5. Attheloadcentersvoltagelevelshouldbebroughtdownatsuitablevaluesforsupplyingdifferenttypesofconsumers.
Consumerscanbecategorizedas:
•bigindustriessuchassteelplants
•mediumandsmallindustries
•officesanddomesticconsumers
Electricityispurchasedbydifferentconsumersatdifferentvoltagelevel.Forexample,bigindustriesmaypurchasepowerat132kV,mediumandbigindustriespurchasepowerat33kVor11kVanddomesticconsumersatratherlowvoltageof230V,singlephase.
Thus,400kVtransmissionvoltageistobebroughtdowntodifferentvoltagelevelsbeforefinallydeliveringpowertodifferentconsumers.Thisisdonebystepdowntransformers.

6. Substations
Substationsaretheplaceswherethelevelofvoltageundergoeschangewiththehelpoftransformers.Apartfromtransformersasubstationhousesswitches(calledcircuitbreakers), meters,relaysforprotectionandothercontrolequipment.
Abigsubstationreceivespowerthroughincominglinesatsomevoltage(say400kV)changeslevelofvoltage(sayto132kV)usingatransformerandthendirectsitoutwardsthroughoutgoinglines.
Atthelowestvoltagelevelof400V,generally3-phase,4-wiresystemisadoptedfordomesticconnections.Thefourthwireiscalledtheneutralwire(N)whichistakenoutfromthecommonpointofthestarconnectedsecondaryofthe6kV/400Vdistributiontransformer.

7. Regional and National Grid
Transmissionformsacriticallinkinthepowersectorvaluechain.India'spowergenerationcapacitiesareunevenlydispersedacrossthecountrycreatinganimbalancebetweenthedistributionofpowerdemandandsupplycentres.
ThecountryhasbeendemarcatedintofiveelectricalRegions:
1.Northern(NR)
2.Eastern(ER)
3.Western(WR)
4.Southern(SR)
5.NorthEastern(NER)
AlltheregionalgridsaresynchronouslyinterconnectedandoperatingassinglegridknownasCentralGridorNationalGrid.

8. Market Structure
BothcentralandstategovernmentsareresponsibleforthedevelopmentofpowersectorinIndia.
POWERGRIDistheCentralTransmissionUtility(CTU)andisresponsibleforwheelingofpowergeneratedbyCentralGeneratingUtilities(CGUs)andinter-stateMegaIndependentPowerProducers.
EachofthefiveregionshasaRegionalLoadDespatchCentre(RLDC),whichistheapexbody,aspertheElectricityAct2003,toensureintegratedoperationofthepowersystemintheconcernedregion.
Additionally,thereisanapexbodyatthenationallevelcalledtheNationalLoadDespatchCentre(NLDC)toensureintegratedpowersystemoperationinthecountry.
TheNLDCandRLDCstogetherformapartofthePowerSystemOperationCorporationLimited(POSOCO),whichisawhollyownedsubsidiaryofPowerGridCorporationofIndiaLimited(PGCIL).

9. Evolution of Transmission Sector
Indianpowersectorremainedclosedtoprivateinvestmentstill1991.Powergenerationwasopenedupforprivateparticipationin1991.
TheElectricity(Amendment)Act,1998,definedtransmissionasaseparateactivityandledtothecreationoftheCTU(currentlyPGCIL)andSTUs.
TheRegulatoryCommissionAct,1998,mandatedthesettingupofanindependentregulatorymechanismatthecentral(CERC)andstatelevel(SERCs).
NationalTariffPolicy2006introducedmandatoryTariffBasedCompetitiveBidding(TBCB) foralltransmissionprojectswiththeobjectiveofpromotingcompetitiveprocurementoftransmissionservices,encouraginggreaterinvestmentbyprivateplayersinthetransmissionsectorandincreasingtransparency&fairnessintheprocess.

10. T&D Lines Length
6,939,529
7,287,413
7,487,977
7,801,098
7,951,486
8,726,092
8,970,112
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
8,000,000
9,000,000
10,000,000
2006-07
2007-08
2008-09
2009-10
2010-11
2011-12
2012-13
ckm
Year
Insixyearsfrom2007to2013,thepowertransmissionsectorregisteredagrowthof4.37%CAGR.

11. Transmission Capacity
Type
Central
State
JV/Private
Total (ckm)
500 kV HVDC
5,948
1,504
1,980
9,432
765 KV
9,898
837
361
11,096
400 kV
79,612
36,179
10,166
125,957
220 kV
10,489
133,484
878
144,851
Total
291,336
As on 31 March, 2014, transmission capacity is given in the following table:

12. Substation Capacity
As on 31 March, 2014, substation capacity is given in the following table:
Type
Central
State
JV/Private
Total (MVA)
765 kV
78,000
2,000
3,000
83,000
400 kV
91,775
85,047
630
177,452
220 kV
7,716
247,311
1,567
256,594
500 kV HVDC
9,500
1,500
2,500
13,500

13. Distribution System
Powerreceivedata33kVsubstationisfirststeppeddownto6kVandwiththehelpofundergroundcables(calledfeederlines),powerflowisdirectedtodifferentdirections.
Atthelastlevel,stepdowntransformersareusedtostepdownthevoltageform6kVto400V.Thesetransformersarecalleddistributiontransformerswith400V,starconnectedsecondary.Suchtransformersaregenerallymountedonpolesincitiesbesidetheroads.Thesearecalledpolemountedsubstations.
Fromthesecondaryofthesetransformers4terminals(R,Y,BandN)comeout.Niscalledtheneutralandtakenoutfromthecommonpointofstarconnectedsecondary.Voltagebetweenanytwophases(i.e.,R-Y,Y-BandB-R)is400Vandbetweenanyphaseandneutralis230V.
Residentialconsumersaresuppliedwithsinglephase230V,50Hz.Soindividualaretobesuppliedwithanyoneofthephasesandneutral.

14. Distributioncompaniestrytomakesurethattheloadsremainevenlybalancedamongthephasesasfaraspossible.Roughlyone-thirdoftheconsumersaresuppliedfromR-N,nextonethirdfromY-NandtheremainingonethirdfromB-N.

15. Competitive Bidding
TheMinistryofPowerhasmandatedthatprocurementoftransmissionservicesinnewprojectsonthebasisoftariff-basedcompetitivebidding.
Thisisdonetoencourageprivatesectorparticipationinthedevelopmentofelectricityinfrastructureandtomovetowardstariffbasedcompetitiveregimefromtheearliercost-plussystem.
Inordertobringinprivatesectorparticipation,theMinistryofPowerhasappointedPFCasBidProcessCoordinator,fortwoprojectsandPFCCL(whollyownedsubsidiaryofPFC)fornineprojects.Outoftheseelevenprojects,fourhavealreadybeentransferredtothesuccessfulbiddersandtheremainingareunderprocess.
Inter-StateTransmissionProjects
Sofar,8inter-statetransmissionprojectshavebeenallottedonthebasisofcompetitivebiddinginvolvinganestimatedcostofaboutINR14,000crores.

16. Projects
SystemstrengtheninginNorthern&WesternRegionsforimportofpowerfromNorthKaranpuraoutsideNR&WRandalsoforpowerevacuationfromprojectswithinWR.
AugmentationofTalcher-IITransmissionsystem
TransmissionschemeforenablingimportofNER-ERsurpluspowerbyNR
TransmissionschemeforKrishnapatnamUMPP-SynchronousinterconnectionbetweenSR&WR(Part-B)
TransmissionProject“SystemstrengtheningcommonforWR&NR”
TransmissionProject“SystemstrengtheningforWR”
TransmissionSystemassociatedwithIPPsofNagapattinam/CuddaloreArea–Package-A

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