Title Addition of Intra-Hour PhotoVoltaic Power Forecast to GTBD Calculation
Next Group
Next Step
Status Approved on 10/13/2020


Date Gov Body Action Taken Next steps
10/13/2020 BOARD Approved
09/23/2020 TAC Recommended for Approval Revision Request Consideration
09/10/2020 PRS Recommended for Approval Revision Request Consideration
08/13/2020 PRS Deferred/Tabled Language Consideration

Voting Record

Date Gov Body Motion Result
10/13/2020 BOARD to approve SCR811 as recommended by TAC in the 9/23/20 TAC Report Passed
09/23/2020 TAC to recommend approval of SCR811 as recommended by PRS in the 9/10/20 PRS Report Passed
09/10/2020 PRS to grant SCR811 Urgent status; to recommend approval of SCR811 as submitted; and to forward SCR811 and its Impact Analysis to TAC with a recommended priority of 2020 and rank of 3080 Passed
08/13/2020 PRS to table SCR811 and refer the issue to ROS and WMS Passed


Status: Approved
Date Posted: Jul 29, 2020
Sponsor: ERCOT
Urgent: Yes
Description: ERCOT is in the process of adding an Intra-Hour PhotoVoltaic Power Forecast (IHPPF). This System Change Request (SCR) updates the formula used by the Resource Limit Calculator to calculate the Generation To Be Dispatched (GTBD) value to include a predicted five-minute solar ramp (PSRR) component. A five-minute solar ramp rate will be calculated from the IHPPF and the Short-Term PhotoVoltaic Power Forecast (STPPF). A manual toggle will be available to select one of the methods as primary source for setting the PSRR value to be used. This PSRR times five and a configurable factor will be used in GTBD to capture the forecasted five-minute solar ramp. This addition would help Security-Constrained Economic Dispatch (SCED) take into account the potential five-minute solar ramp in its five-minute Base Points and would take the burden off of Regulation Service to cover the five-minute gain or loss of generation resulting from variations in solar irradiance and instead dispatch the energy economically. This change will also aid reducing frequency recovery duration following events that occur during times with significant solar up and down ramps. Although there will be inherent forecast error in the PhotoVoltaic forecast, this change will give a better indication to SCED via GTBD of the level of solar generation that will be available in the next five minutes, as compared to the current assumption that the solar generation will persist at the same level as at the beginning of the five-minute interval. ERCOT will analyze the five-minute out forecast performance and accuracy of projected solar generation ramp direction before the intra-hour solar ramp forecast component is activated in the GTBD formula.
Reason: Market efficiencies or enhancements

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