Title: Dynamic Ramp Rates Use in SCED
Next Group:
Next Step:
Status: Approved on 01/18/2011
Effective Dates:


Date Gov Body Action Taken Next Steps
01/18/2011 BOARD Approved
12/06/2010 TAC Recommended for Approval ERCOT Board consideration of NPRR282
11/18/2010 PRS Recommended for Approval TAC consideration of NPRR282
10/21/2010 PRS Recommended for Approval PRS Impact Analysis review

Voting Record

Date Gov Body Motion Result
01/18/2011 BOARD To approve NPRR282 as recommended by TAC in the 12/6/10 TAC Report. Passed
12/06/2010 TAC To recommend approval of NPRR282 as recommended by PRS in the 11/18/10 PRS Report. Passed
11/18/2010 PRS To endorse and forward the 10/21/10 PRS Report and Impact Analysis for NPRR282 to TAC and to assign NPRR282 a priority of Critical. Passed
10/21/2010 PRS To recommend approval of NPRR282 as amended by the 10/18/10 Luminant Energy Company LLC comments. Passed

Vote tallies here reflect individual votes, not the weight of the votes by market segment. Affirmative votes are not recorded in these vote tallies. For additional details on the voting record, please consult the Recommendation or Action Report, or the official vote tally if available, as posted in the key documents.


Status: Approved
Date Posted: Sep 28, 2010
Sponsor: Calpine
Urgent: No
Sections: 2.1,,
Description: This Nodal Protocol Revision Request (NPRR) proposes revisions that are intended to result in more reasonable Dispatch of Generation Resources when a telemetered Base Point requires the Resource to employ technologies that in turn change the Resource’s ramp rate. For example, when Security-Constrained Economic Dispatch (SCED) generates a new Base Point for a unit that is currently at baseload, SCED uses a static ramp rate found in the Resource Parameters database that does not accurately reflect the dynamic ramp rate that the unit can deliver as it leaves baseload status (ten MW/min. for some units) and goes into duct burners (one MW/min. for some units) or through duct burners into other technologies such as certain forms of power augmentation. Instead of using the declared static ramp rates at designated output levels, SCED should use a dynamic ramp rate that can be telemetered by the Qualified Scheduling Entity (QSE) to ERCOT using the Inter-Control Center Communications Protocol (ICCP) database with an update rate of two or four seconds, which will better match the unit’s ramp rate capability during the SCED execution. The up and down ranges of this telemetered dynamic ramp rate are best defined by ERCOT based on its experience in the Nodal Market trials and its view of the SCED Base Point outcomes and its analysis of the Generation Resource Energy Deployment Performance (GREDP) scores and Regulation Service deployed.
Reason: Market trials demonstrate that plants are Dispatched at levels that are unachievable during the five-minute SCED intervals. These situations occur when SCED uses a declared static ramp rate for an output level that does not apply over the output range implicated by the new telemetered Base Point.

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