SCR811  Addition of Intra-Hour PhotoVoltaic Power Forecast to GTBD Calculation

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.