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NPRR #487 · Revision Request

NPRR487  QSGR Dispatch Adjustment

Approved Urgent sponsor Luminant Energy LLC posted 2012-10-03 ercot.com
ReasonThe amount of time that QSGRs are being called upon to resolve congestion has highlighted a localized Locational Marginal Price (LMP) formation problem that this NPRR seeks to resolve. When a transmission constraint becomes active in SCED that requires a Base Point to a QSGR that is less than its physical Low Sustained Limit (LSL) (e.g., Base Point to 5 MW when its physical LSL is 45 MW), the QSGR is brought On-Line to its physical LSL within ten minutes to comply with the Base Point. The LMP at the QSGR bus when the initial positive Base Point is issued corresponds to the Mitigated Offer Cap of the QSGR (assuming the constraint is non-competitive); however, after the QSGR reaches its physical LSL, SCED will often no longer bind for long periods of time on the transmission constraint (i.e. the constraint becomes "inactive") because the amount of generation needed at the QSGR site to resolve the constraint was less than the physical LSL of the QSGR (e.g., 40 MW less using the 5 MW Base Point and 45 MW LSL described above). While this situation is occurring, LMPs at the QSGR site are clearing below the Mitigated Offer Cap of the QSGR, which means the QSGR is likely operating at a short-run marginal cost loss to allow SCED to manage congestion. With the 9/12/12 WMS vote to revise the Verifiable Cost Manual formula that establishes the Mitigated Offer Cap for QSGRs to amortize a QSGR’s start cost across all hours of historic run time during a defined period, including those at which it was being called upon to operate at a short-run marginal cost loss for the reasons outlined above, it is important to correct this localized pricing problem as quickly as possible.
Created2012-10-18
Approved2013-03-19
Sections Affected
3.8.36.6.5.38.1.1.4.1
Summary
This Nodal Protocol Revision Request (NPRR) modifies the emergency energy Settlement treatment of a Quick Start Generation Resource (QSGR) that is brought On-Line with a Base Point less than or equal to its Resource registration applicable Seasonal net minimum sustainable rating. The changes remove the limitation for compensation using an Energy Offer Curve price that is capped by the Mitigated Offer Cap (adjusted to include variable Operations and Maintenance (O&M)). Currently the limitation is two "q" Settlement Intervals. The NPRR would allow this compensation until Security-Constrained Economic Dispatch (SCED) no longer needs the QSGR to generate, subject to performance of the QSGR Decommitment Decision Process. The NPRR also details the QSGR Decommitment Decision Process.
Timeline