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NPRR #348 · Revision Request

NPRR348  Generation Resource Start-Up and Shut-Down process

Approved sponsor ERCOT posted 2011-04-06 ercot.com
ReasonUnder the current Nodal Protocols, a Resource Status of "ONTEST" is telemetered for Resources that are either starting up or shutting down. This potentially causes two problems for the ERCOT system and the ERCOT Operators. The first problem can occur when a Qualified Scheduling Entity (QSE) telemeters a Resource Status of "ONTEST" and SCED sends a Base Point to that Resource equal to its current telemetered output. This results in ERCOT deploying Regulation to account for any movement by that Resource between SCED executions. There have been periods when a number of Resources have started up or shut down quickly and simultaneously. This can cause frequency issues and may result in ERCOT manually executing SCED and deploying additional Ancillary Services. These concerns will be greatly reduced if Resources are required to follow SCED instructions when they are receiving base-points at or above their LSL. A new "SHUTDOWN" Resource Status will force SCED to Dispatch a Resource down to 0 MW according to its ramp rate. This will ensure that when a Resource is intending to shutdown, SCED will only be ramping the Resource down and not changing ramp direction. This logic will provide ERCOT visibility to where the Resource is planned to go in the next five minutes and will provide a method for a Resource to come off-line as required even if it is operating above its LSL. The second problem is that ERCOT Operators are not currently able to distinguish easily between periods when Generation Resources are performing testing and when they are starting up/shutting down. Discontinuing the use of "ONTEST" during start-up/shut-down will address this concern.
Created2011-04-21
Approved2011-09-20
Sections Affected
3.9.16.4.2.46.4.36.5.7.26.5.7.86.6.58.1.1.4.1
Summary
As part of this Nodal Protocol Revision Request (NPRR), Protocol language concerning the use of the "ONTEST" Resource Status during Start-Up and Shut-Down has been removed. Language has been added to address the Start-Up and Shut-Down processes. For Start-Up, language is added so that Resources are exempt from Base-Point Deviation Charges and Generation Resource Energy Deployment Performance (GREDP) metrics when the Resources average base-point value is below the average telemetered Low Sustainable Limit (LSL). The expectation is that when a Resource is receiving base-points below its LSL, the Resource is starting up/shutting down and not necessarily responding to Security Constrained Economic Dispatch (SCED) instructions. For Shut-Down, a new Resource Status is created called "SHUTDOWN". This status will be used by the Resource Limit Calculator (RLC) to calculate dispatch limits for SCED which ramp a Resource down to 0 MW according to the Resource’s provided ramp rate. Again, a Resource will be exempt from Base-Point Deviation Charges and GREDP metrics when the Resource’s average base-point is below the average telemetered LSL.
Timeline