PROCEDURE FOR:: REAL TIME CONGESTION MANAGEMENT

ASSESSMENT OF TTC TTC/ATC assessment is carried out after construction & solution of a base case power system model for a representative scenario EHV system modelled upto 220KV level(except NER modelled upto 132KV) Normally all units > 50MW with switching at 132KV level & above would be modelled Loads would be lumped at 220 / 132KV Actual data or data as per CEA transmission planning criterion

ASSESSMENT OF TTC Separate base case for export & import & TTC calculations for both peak/off-peak Network topology :: data from CTU / STU Unit availability:: LGBR Actual Generation:: As per past trends/anticipation Actual Demand:: As per data furnished/LGBR/past trends MVAR Demand:: CEA manual on transmission criterion planning or data furnished

Normal operating limts for Line:: CEA manual on transmission criterion planning Emergency operating limit of line:: 110% of Normal ICT loading:: 90% of MCR In case of non availability of data/additional data requirement - reasonable assumptions to be made TTC between two areas calculated by increasing generation in exporting area and load in importing area till constraints are hit for a credible contingency ASSESSMENT OF TTC

Credible contingency:: -Outage of a single transmission element -Outage of the largest unit in a generating station & transmission element All base case loadings are within normal operating limits After credible contingency all line loadings are within emergency operating limits and voltage as per IEGC defined range ASSESSMENT OF TTC

TTC would be limited by : -violation of voltages -violation of line operating limits in base case -violation of emergency limits in contingency ASSESSMENT OF TTC

TRM kept to ensure that the system is reliable under a reasonable range of uncertainities Computation of TRM:: - 2% of anticipated peak demand(MW) -power number in MW for the IEGC frequency range (with load damping of 4 % with/without FGMO) - size of the largest generating unit - size of largest anticipated infeed ATC = TTC – TRM ATC is the transfer capability commercially available for scheduling ASSESSMENT OF TRM/ATC

SLDCs shall assess the TTC/ATC for intra-regional corridors & exchange of power with ISTS RLDCs shall determine TTC/ATC at regional level after receipt of above & other data for TTC computation from SLDCs. RLDCs would determine TTC/ATC for inter-regional corridors & intra-regional corridors & between two or group control areas TTC/ATC assessment shall be three months in advance upto the fourth month All these data shall be forwarded to NLDC for computation/verification of intra-regional/inter-regional TTC/ATC PROCEDURE FOR ATC/TTC/RM DECLARATION

ISGS-I ISGS-II STATE-ASTATE-B ISTS NETWORK

All TTC/ATC declarations to be put on RLDC/NLDC website & also communicated as per Format-I Revision of TTC/ATC may be done by NLDC based on: - inputs received from SLDCs/RLDCs - change in network topology - change in anticipated Load/generation - based on own observation PROCEDURE FOR ATC/TTC/RM DECLARATION

SLDCs/RLDCs/NLDC would display the actual real time power flow Vis-a-Vis the TTC declared as per Format-II & voltages upstream/downstream Reasons for Consideration of congestion:: - Grid voltage downstream/upstream beyond operating range -real time power flow exceeds the ATC for one time block for the congested corridor -loading of transmission lines beyond operating limit PROCEDURE FOR REAL TIME CONGESTION DECLARATION

In case actual flow in inter/intra regional corridor exceeds ATC continuously for two time blocks NLDC would issue a warning notice SLDCs on noticing congestion can inform RLDC who in turn will inform NLDC If power flow is as per schedule but congestion is due to a forced outage :: OA transaction shall be revised first followed by TTC revision If power flow is as per schedule and there is congestion in terms of voltages/line loadings without any forced outages, TTC shall be revised In case of continued persistance of congestion and no action from defaulting constituents notice of application of congestion charges would be issued PROCEDURE FOR REAL TIME CONGESTION DECLARATION

Applicable simultaenously on all entities upstream / downstream Payable by entities causing congestion and receivable by entities relieving congestion Congestion charges may be applied pan india being applicable for entities in one region causing intra-regional congestion in a separate region Shall be applicable only after two time blocks of issue of the notice Once applied will remain in force for 8 time blocks(2 hours) Congestion charges would not be applied for more than four times in a day to prevent continued flip-flops APPLICABILITY OF CONGESTION CHARGE

Congestion charges levied for the fourth time would remain in force for the rest of the day. If the congestion charges continues into next day the same shall be considered as 1 st time for the day. Shall be lifted only after the 2 hour period and when power flow falls below ATC and remains below ATC level for at least one time block At frequency below 50 Hz, congestion charge would be levied for overdrawal in the importing control area and at frequencies above 50Hz, congestion charge would be levied for under-drawal in the exporting control area. APPLICABILITY OF CONGESTION CHARGE

NERER NR SR WR U/D-A O/D-B U/D-C O/D-D U/D-X O/D-Y SF > 50.00Hz A,C CAUSING CONGESTION SF < 50.00Hz Y CAUSING CONGESTION CONGESTED LINKS ER-NR & WR-ER

Congestion charge present rate:: 545 p/Kwh At the end of the operating day RLDC/NLDC would indicate all time blocks where congestion charges applicable Computation using SEM data and Frequency Congestion charge account to be settled on weekly basis and maintained/operated by RLDCs Statement of congestion charge disbursal to be issued by RPCs on weekly basis Constituents required to pay into congestion charge account within 10 days of issue of accounts Delay beyond 12 days will attract 0.04% S.I per day RLDC to release disburse towards payments within 3 days of receipt. CONGESTION CHARGE-ACCOUNTING & SETTLEMENT

Undisbursed amount if any would be utilized as per instruction of CERC RLDC to furnish data regarding undisbursed amount to the commission on a six monthly basis CONGESTION CHARGE-ACCOUNTING & SETTLEMENT

FORMAT FOR DECLARING ATC/RM/TTC BY NLDC

DISPLAY FOR CONGESTION MONITORING

PROCEDURE FOR REAL TIME CONGESTION DECLARATION

APPLICABILITY OF CONGESTION CHARGE

CONGESTION CHARGE-ACCOUNTING & SETTLEMENT