1 technical and commercial aspects k.ramakrishna dgm, srldc dgm, srldc
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Technical and Commercial Technical and Commercial AspectsAspects
K.RAMAKRISHNA K.RAMAKRISHNA DGM, SRLDCDGM, SRLDC
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Types of Inter-Types of Inter-connectionsconnections
AC links (Synchronous mode)AC links (Synchronous mode) DC Links (Asynchronous DC Links (Asynchronous
mode) mode)
throughthrough
- HVDC line and - HVDC line and Convertors/InvertorsConvertors/Invertors
- HVDC Back to Back system - HVDC Back to Back system
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Features of AC linksFeatures of AC links Low cost (up to some distance)Low cost (up to some distance) Increased Fault level and InertiaIncreased Fault level and Inertia Synchronous operation (same Synchronous operation (same
frequency)frequency) No control on Power flowNo control on Power flow Fault in one Region may affect other Fault in one Region may affect other
RegionRegion Over voltage problemsOver voltage problems Huge Power is lost in Equalizing the Huge Power is lost in Equalizing the
frequencies thereby loosing the frequencies thereby loosing the advantage in Differential frequencyadvantage in Differential frequency
No run back schemesNo run back schemes
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Features of DC Features of DC LinksLinks
Higher capital cost Higher capital cost Asynchronous operationAsynchronous operationImmunity from faults in both Immunity from faults in both RegionsRegionsControl on Power flowControl on Power flowOptimization through Optimization through frequency frequency DifferentialDifferential
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High lights of various High lights of various HVDC linksHVDC links
Bypass arrangement Bypass arrangement (ex.Bhadrawati,Gazuwaka)(ex.Bhadrawati,Gazuwaka)
Power order setting Power order setting Minimum Power for deblockingMinimum Power for deblocking Ramping rate variationRamping rate variation Run Back systems / Power Demand Run Back systems / Power Demand
Overrides (PDOs)Overrides (PDOs) Automatic Filter switching for Reactive Automatic Filter switching for Reactive
power requirementpower requirement
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TALCHER KOLAR LINKTALCHER KOLAR LINK ONE OF THE LONGEST HVDC LINES IN THE ONE OF THE LONGEST HVDC LINES IN THE
WORLDWORLD DESIGNED TO EVACUATE DESIGNED TO EVACUATE 2000 MW2000 MW COMMISSIONED IN ADVANCE TO UTILISE NON-COMMISSIONED IN ADVANCE TO UTILISE NON-
PEAK SURPLUS POWER OF EASTERN REGIONPEAK SURPLUS POWER OF EASTERN REGION COMMISSIONED 9 MONTHS AHEAD OF COMMISSIONED 9 MONTHS AHEAD OF
SCHEDULESCHEDULE COST INCURRED COST INCURRED Rs 3,100 CRORES Rs 3,100 CRORES AGAINST AGAINST
APPROVED COST OF APPROVED COST OF Rs 3,866 CRORESRs 3,866 CRORES:- SAVING OF :- SAVING OF NEARLY NEARLY 800 CRORE RUPEES800 CRORE RUPEES
THE PROJECT HAS USED THE PROJECT HAS USED APPROXIMATELY 90,000 TONNES OF APPROXIMATELY 90,000 TONNES OF STEEL AND 16,000 KM OF CABLES STEEL AND 16,000 KM OF CABLES
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TALCHER-KOLARTALCHER-KOLAR IMPORT OF 12728MUs FROM ER THROUGH TALCHER-KOLAR UPTO OCT-04
YEAR ---YEAR --->>
20022002 20032003 20042004
MONTHMONTHSS
TOTAL TOTAL ENERGY ENERGY (IN MU)(IN MU)
MAX MAX FLOW FLOW
(IN MW)(IN MW)
TOTAL TOTAL ENERGENERGY (IN Y (IN MU)MU)
MAX MAX FLOW FLOW
(IN (IN MW)MW)
TOTAL TOTAL ENERGY ENERGY (IN MU)(IN MU)
MAX MAX FLOW FLOW
(IN (IN MW)MW)
JANJAN ------ ------ 311311 850850 805805 15281528
FEBFEB ------ ------ 273273 10101010 701701 15081508
MARMAR ------ ------ 491491 13161316 837837 16001600
APRAPR ------ ------ 473473 11831183 923923 15001500
MAYMAY ------ ------ 172172 10261026 652652 13851385
JUNJUN ------ ------ 277277 994994 688688 14161416
JULJUL ------ ------ 319319 10751075 759759 14901490
AUGAUG ------ ------ 346346 10881088 628628 13411341
SEPSEP 66 200200 512512 15331533 742742 15521552
OCTOCT 5858 500500 508508 1458 1458 829829 15501550
NOVNOV 7777 500500 470470 1048 1048
DECDEC 241241 750750 630630 1383 1383
TOTALTOTAL 382382 47824782 75647564
MAXMAX 750750 15331533 16001600
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Defense MechanismDefense Mechanism
Run Back scheme in Gazuwaka HVDC Run Back scheme in Gazuwaka HVDC Power level reduces to 250MW ,Power level reduces to 250MW ,
- If Gazuwaka East bus Voltage - If Gazuwaka East bus Voltage <320kV <320kV
- If Gazuwaka ICT O/L alarm actuates- If Gazuwaka ICT O/L alarm actuates- If Jeypore ICT trips- If Jeypore ICT trips- If Jeypore-Indravati Line trips- If Jeypore-Indravati Line tripsPower level reduces to 150MW,Power level reduces to 150MW,- If East side frequency <49Hz and - If East side frequency <49Hz and if df/dt>=-0.3 Hz./sec. if df/dt>=-0.3 Hz./sec.
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Defense Mechanism for Defense Mechanism for Talcher Kolar HVDC linkTalcher Kolar HVDC link
In case of any pole tripping, Inter-trip signal In case of any pole tripping, Inter-trip signal generated to trip associated AC lines at generated to trip associated AC lines at
Yerraguntla(AP), Yerraguntla(AP), Kolar, Hoody, Somanahalli(Karnataka)Kolar, Hoody, Somanahalli(Karnataka)Sriperambadur, Salem and Hosur (TN)Sriperambadur, Salem and Hosur (TN)
Mode of Oprn. Mode of Oprn. Power Level for Inter-trip Power Level for Inter-tripMono polar >400MW and pole tripsMono polar >400MW and pole tripsBi-polar >800MW/pole and one pole trips Bi-polar >800MW/pole and one pole trips Bi-polar >200MW/pole and both pole tripBi-polar >200MW/pole and both pole trip
contd..contd..
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Defense Mechanism forDefense Mechanism for Talcher Kolar HVDC link Talcher Kolar HVDC link
Further PDOs at HVDc Kolar, Further PDOs at HVDc Kolar,
Condition Power reduced Condition Power reduced toto
If only 2 lines are available 500MWIf only 2 lines are available 500MW
If only 3 lines are available 1000MWIf only 3 lines are available 1000MW
If only 4 lines are available 1500MWIf only 4 lines are available 1500MW
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Experience of SR Experience of SR in operation of IR linksin operation of IR links
Congestion in associated AC network in Congestion in associated AC network in (ex. 1)Over loading of Raipur-Rourkela, (ex. 1)Over loading of Raipur-Rourkela,
Raipur-Bhadravati, Chandrapur-Bhadravati Raipur-Bhadravati, Chandrapur-Bhadravati in case of more import from WR.in case of more import from WR.
2) Over loading of Chadrapur-Parli 2) Over loading of Chadrapur-Parli in case of more export to WR in case of more export to WR
3) Over loading of Jeypore-Jayanagar, Jeypore-3) Over loading of Jeypore-Jayanagar, Jeypore-Meramundali, Jeypore-Indravati, Talcher-Meramundali, Jeypore-Indravati, Talcher-Banjinagar(220kV), Gajuwaka-Vijayawada in Banjinagar(220kV), Gajuwaka-Vijayawada in case of more import from ER through case of more import from ER through GazuwakaGazuwaka
Reduced fault level at JeyporeReduced fault level at Jeyporecontd…contd…
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Experience of SR Experience of SR in operation of IR linksin operation of IR links
Problems in Converter transformers at Problems in Converter transformers at Gazuwaka ( HENCE SUGGESTED FOR Gazuwaka ( HENCE SUGGESTED FOR STANDBY CONVERTER TRANSFORMERS AT STANDBY CONVERTER TRANSFORMERS AT ALL THE PLACES)ALL THE PLACES)
Harmonics in neutral of Kolar ICT and flow of Harmonics in neutral of Kolar ICT and flow of the same in associated systemthe same in associated system
Over voltage at Kolar due to Switching of Over voltage at Kolar due to Switching of filtersfilters
High losses in Monopolar- Metallic return High losses in Monopolar- Metallic return mode.mode.
Annual Maintenance of Poles.Annual Maintenance of Poles. CURTAILMENT OF STOA CURTAILMENT OF STOA
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LOSSES IN HVDC LOSSES IN HVDC SYSTEMSYSTEM
POWER ORDER IN MW
% LOSS
MAX CAPACITY MIN. CAPACITY (50MW )
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Loss optimizationLoss optimization
IR flows can influence SR System IR flows can influence SR System LossLoss
By importing more through KolarBy importing more through Kolar By exporting to WR from By exporting to WR from
Ramagundam-Chandrapur LinkRamagundam-Chandrapur Link During high frequency, More During high frequency, More
import from Gazuwaka preferred.import from Gazuwaka preferred.
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Losses applicable Losses applicable for various transactionsfor various transactions
1. 1. For share from ER ISGS- ER+SR lossesFor share from ER ISGS- ER+SR losses2. For Talcher St-II power through 2. For Talcher St-II power through
Kolar, - SR lossesKolar, - SR losses3. For Talcher-St-II power when wheeled3. For Talcher-St-II power when wheeled through Gazuwaka – ER+SR lossesthrough Gazuwaka – ER+SR losses through Bhadravati – ER+WR+SR through Bhadravati – ER+WR+SR
losseslosses4. Wheeling of ER power through SR 4. Wheeling of ER power through SR – – ER+ SR lossesER+ SR losses
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Normative % Losses of Normative % Losses of Central sector in various Central sector in various
RegionsRegionsER ~ 3 to 3.5%ER ~ 3 to 3.5%SR ~ 2.8 to 3.8%SR ~ 2.8 to 3.8%WR ~ 6 to 6.5%WR ~ 6 to 6.5%NR ~ 3 to 4%NR ~ 3 to 4%
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Priority of Exchanges Priority of Exchanges through IR linksthrough IR links
Long Term transactions Long Term transactions
(ISGS Allocation to Beneficiaries (ISGS Allocation to Beneficiaries of the of the same region)same region)
Wheeling of ISGS share of Wheeling of ISGS share of Beneficiaries in Beneficiaries in other regionsother regions
any other long term transactions any other long term transactions approvedapproved
STOA TransactionsSTOA Transactions
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PROCEDURE FOR PROCEDURE FOR CURTAILEMENTCURTAILEMENT
In case of transmission constraint , In case of transmission constraint , if curtailment is necessary then,if curtailment is necessary then,
Short term customers firstShort term customers first Long term customers nextLong term customers next
Within the category,Within the category, OA customers haveOA customers have
curtailment on pro curtailment on pro rata basisrata basis
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Commercial AspectsCommercial Aspects
Metering and Scheduling points :Metering and Scheduling points :
SR-WRSR-WR
South Bus of HVDC BhadravatiSouth Bus of HVDC Bhadravati
SR-ERSR-ER
East Bus of HVDC GazuwakaEast Bus of HVDC Gazuwaka
AC Inter connector of Talcher AC Inter connector of Talcher St-I St-I and St-IIand St-II
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TSTPP St-II scheduling and TSTPP St-II scheduling and DespactchDespactch
TSTPP St-II furnishes DC to SRLDC with a copy TSTPP St-II furnishes DC to SRLDC with a copy to ERLDC.to ERLDC.
SRLDC to carry out rest of the Scheduling SRLDC to carry out rest of the Scheduling processprocess
Talcher/ Gazuwaka set points to be decided in Talcher/ Gazuwaka set points to be decided in consultation with ERLDCconsultation with ERLDC
Talcher HVDC controlled by ERLDC.Talcher HVDC controlled by ERLDC. Gazuwaka HVDC controlled by SRLDC.Gazuwaka HVDC controlled by SRLDC. In case of Talcher Pole tripping TSTPP St-II In case of Talcher Pole tripping TSTPP St-II
Power wheeled through Gazuwaka/BhadrawatiPower wheeled through Gazuwaka/Bhadrawati
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TSTPP St-II UI TSTPP St-II UI accounting accounting
TSTPP St-II – a SR ISGS embedded in ER TSTPP St-II – a SR ISGS embedded in ER system system
TSTPP St-II UI @ ER frequency and to pay to TSTPP St-II UI @ ER frequency and to pay to SR poolSR pool
Net injection of TSTPP St-II = (Talcher HVDC Net injection of TSTPP St-II = (Talcher HVDC Energy- flow on I/C betweenTalcher St-I&II)Energy- flow on I/C betweenTalcher St-I&II)
Variation in TSTPPSt-II Generation results in Variation in TSTPPSt-II Generation results in ER-SR UI, if HVDC set point not changedER-SR UI, if HVDC set point not changed
Sometimes –ve UI occurs if ER – SR Sometimes –ve UI occurs if ER – SR SCHEDULE flow is not changed in SCHEDULE flow is not changed in accordance with ER-SR frequency accordance with ER-SR frequency differential.differential.
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Inter Regional UI Inter Regional UI settlement settlement IR UI calculated by each REB at IR UI calculated by each REB at
respective frequencyrespective frequency IR UI Payment on 1IR UI Payment on 1stst charge basis charge basis
without pro-rata reduction/averaging without pro-rata reduction/averaging outout
Importing Region to pay on lesser of Importing Region to pay on lesser of the two principle.the two principle.
Differential due to difference in UI Differential due to difference in UI rates on a/c of frequency deposited by rates on a/c of frequency deposited by importing region in their IRE account.importing region in their IRE account.
WR UI ER UI
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IRE Settlement IRE Settlement
Such accrued amounts of Such accrued amounts of IRE account to be shared on IRE account to be shared on 50:50 basis between 50:50 basis between Beneficiaries of both RegionsBeneficiaries of both Regions
By way of credit in By way of credit in Transmission charges of Transmission charges of CTUCTU
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Status of IRE a/c settlement Status of IRE a/c settlement in SR & other regionsin SR & other regions
100% settled to SR constituents 100% settled to SR constituents except for provision for Revisionsexcept for provision for Revisions
Rs. 5 cr. Released WR Rs. 5 cr. Released WR constituentsconstituents
Release to ER will start next Release to ER will start next week.week.
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INTER-REGIONAL EXCHANGES WR A/C INTER-REGIONAL EXCHANGES WR A/C DETAILS UPTO 93 WKSDETAILS UPTO 93 WKS
TILL 10/10/04TILL 10/10/04
1. NET ENERGY TRANSACTION IS 146 MU (IMPORT BY SR).
2. AMOUNT ACCRUED IN SREB – IRE DUE TO DIFF. IN WR A/C = 41.83Crs
3. AMOUNT TO BE ACCRUED IN WREB – IRE DUE TO DIFF. IN SR A/C = 27.71Crs
4. AMOUNT DUE TO SR CONSTITUENTS ON 50:50 BASIS = 34.73Crs
5. AMOUNT ALREADY DISBURSED TO SR CONSTITUENTS = 33.39Crs
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Procedure for Bidding RLDC concerned shall invite bids if
transmission capacity reservation sought by short term customer is more than the availability in a particular transmission corridor
The floor price of the bids for short term customer shall be about 1/4 th rate chargeable from long term customer and will be in Rupees per MW per day.
If customer gets the quantum of power he has bid for – he has to pay the price quoted by ‘last’ customer.
If customer gets a quantum lesser than that he has bid for – he gets to pay his bid price
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