Wind Dispatch Issues and Questions – Part 2 5. What wind output value will be used in the UDS price-based congestion management calculations? Will it be the DNE/DDP or the 5-minute forecast value or something else? The last answer I received on this was that the algorithm would use "several inputs" including the plant's current output, the potential output given current and 5-minute forecast wind conditions. I don't know what this means. The ISO will have four useful data points for each wind plant: Real-Time High Operating Limit (RTHOL) which is the Participant’s estimate of what the plant can produce with optimal wind conditions and considering any equipment outages; Wind High Limit (WHL) which is the of what the Participant’s “nowcast” plant could produce if not curtailed given current wind conditions and considering any equipment outages Actual current output of the wind plant; Short term plant-specific wind forecast (assuming no constraints) The short term wind forecast takes advantage of the first three items to both create the current and to identify, understand and “next 5 minutes” forecast, correct any errors and biases in that forecast. Given the encouraging level of accuracy exhibited by the short term forecast to date, the short term forecast will be used to value for each establish an “Ecomax” wind plant in the first stage of the DNE dispatch algorithm. The first stage of the algorithm solves the traditional economic dispatch problem, assuming the forecast is accurate. The second stage determines the reliability limit for each wind plant, taking into consideration the need to maintain the system energy balance and the need to ensure transmission line flows remain within acceptable limits if the wind forecast is not accurate. The DNE limit telemetered to the wind plant is the lesser of the reliability-based limit for the plant and the economic dispatch level, as indicated by the plant’s economic offer curve and the current LMP. In all cases the DNE limit will plant’s be capped at the network interconnection capacity established in the resource’s interconnection agreement. If a wind DNE limit is less than its short term forecast value, the plant is plant’s potentially constrained and potentially able to set price. However, if low wind conditions mean the expected output is below the DNE limit, the plant is plant’s effectively unconstrained and would not be setting price.
Wind Dispatch Issues and Questions – Part 2 5. What wind output value will be used in the UDS price-based congestion management calculations? Will it be the DNE/DDP or the 5-minute forecast value or something else? The last answer I received on this was that the algorithm would use "several inputs" including the plant's current output, the potential output given current and 5-minute forecast wind conditions. I don't know what this means. The ISO will have four useful data points for each wind plant: Real-Time High Operating Limit (RTHOL) which is the Participant’s estimate of what the plant can produce with optimal wind conditions and considering any equipment outages; Wind High Limit (WHL) which is the Participant’s “nowcast” of what the plant could produce if not curtailed given current wind conditions and considering any equipment outages Actual current output of the wind plant; Short term plant-specific wind forecast (assuming no constraints) The short term wind forecast takes advantage of the first three items to both create the current “next 5 minutes” forecast, and to identify, understand and correct any errors and biases in that forecast. Given the encouraging level of accuracy exhibited by the short term forecast to date, the short term forecast will be used to establish an “Ecomax” value for each wind plant in the first stage of the DNE dispatch algorithm. The first stage of the algorithm solves the traditional economic dispatch problem, assuming the forecast is accurate. The second stage determines the reliability limit for each wind plant, taking into consideration the need to maintain the system energy balance and the need to ensure transmission line flows remain within acceptable limits if the wind forecast is not accurate. The DNE limit telemetered to the wind plant is the lesser of the reliability-based limit for the plant and the plant’s economic dispatch level, as indicated by the plant’s economic offer curve and the current LMP. In all cases the DNE limit will be capped at the network interconnection capacity established in the resource’s interconnection agreement. If a wind plant’s DNE limit is less than its short term forecast value, the plant is potentially constrained and potentially able to set price. However, if low wind conditions mean the plant’s expected output is below the DNE limit, the plant is effectively unconstrained and would not be setting price.
wind_dispatch_issues_and_questions_part2.docx