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Review of Abnormal MCPEs. April 19 th through April 27 th , 2004 May 12 th , 2004 Market Operations Support Brandon Whittle. April 19 th , 2004. MCPEs NH Shadow Prices. April 19 th , 2004. No Limit Changes on NH CSC
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Review of Abnormal MCPEs April 19th through April 27th, 2004 May 12th, 2004 Market Operations Support Brandon Whittle
April 19th, 2004 • MCPEs • NH Shadow Prices
April 19th, 2004 • No Limit Changes on NH CSC • Operator Actions consistent with procedures, no evidence of over or under constraint • Flow controlled to 85-90% of posted limit – Why? • Blue – NH Limit • Red – NH Flow
April 19th, 2004 • Why were flows managed fairly conservatively? • TDSP notified ERCOT of need for lower limit due to post-contingency voltage instability • ERCOT currently does not have tools to perform real-time voltage stability testing. (Release 3) • ERCOT Operations chose to be conservative and controlled to a lower than posted limit • New procedures being discussed to change posted limit
April 19th, 2004 • Contributing Factor – Load Change • 200 MW load forecast increase in ERCOT between 15:45 and 16:00 • 229 MW load forecast increase in load in Houston Zone • This causes the predicted flow across the N-H CSC to be significantly higher, requiring more BES to be cleared, thus higher prices • CSC flowcsc=
April 22nd, 2004 • MCPEs • NH, SH Shadow Prices
April 22nd, 2004 • Interval 14:15 West MCPE -999.01 • Extremely high Shadow Prices and MCPEs were mitigated after market clearing. Prices shown are mitigated prices which are marginal bids cleared. • All available BES is used to solve a zonal constraint if necessary, using power balance as a limit. • Due to exhaustion of available bid stacks and West Zone BES bid of -999.01
April 22nd, 2004 April 22nd, 2004 • Blue – NH Limit • Red – NH Flow
April 22nd, 2004 • Significant Limit change on N-H for 0700 • Related to planned outage of King to Kuykendall • NH and SH constraints active, in both cases Houston UBES is necessary to solve • N-H curtailment contributes to loading on SH constraint • Operator actions • No evidence of over constraint • Operator could have mitigated by easing into the limit change although not supported in procedures
April 22nd, 2004 • New Development in Procedures • ERCOT recognized problem and proposed internal solution • Solution in Transmission and Security Desk Procedures 2.2.1 step 2.2 • Operator is to gradually reduce flows across a CSC in preparation for a limit change
April 26th, 2004 • MCPEs • 1645 Interval high, no congestion
April 26th, 2004 • 1606 Generation Trip • Low Frequency • Increase in Balancing Energy necessary to replace RRS deployment • Blue – ERCOT Frequency • Red – Balancing deployed
April 27th, 2004 • MCPEs • Shadow Prices Northeast to North
April 27th, 2004 • Blue – EN Limit • Red – EN Flow
April 27th, 2004 • Operator Actions were good, let off constraint as flow decreased • Limits were lowered on NE-N due to a combination of several outages • Increase in Balancing required to meet load contributed to rise in MCPEs
Recommendations • Ease into planned CSC limit changes • Requires procedure change – DONE • Post limits CSC limits in Real Time • In discussion, enhancements to made progressively • Enhance BES market to limit use of zones with negligible affect on constraint solution • Currently planned for Release 5 • Requires Protocol changes • Solutions currently being studied • Shadow Price Cap? • Virtual Bids? • Penalty Weight Change?