A Methodology for Dynamic Procurement of Secondary Reserve Capacity in Power Systems with Significant vRES Penetrations

The European pathway to carbon neutrality indicates strong investments in variable renewable energy sources. Demand-side and variable renewable players rely on forecasts to participate in day-ahead markets closing between 12 and 37 hours ahead of real-time operation. As such, the further from the real-time operation those forecasts are provided, the higher their errors and the uncertainty. Deviations from the market schedules are balanced using real-time reserves. Traditionally, transmission system operators (TSOs) use a symmetrical procurement of up and down reserves based on the expected demand. This work considers the computation of a dynamic up and down procurement of secondary capacities by considering the expected deviations, using the day-ahead programmed and expected dispatches of variable renewables, demand, other technologies, and the cross-border capacities. The study uses operational open data from the Spanish TSO from 2019 to 2022. The proposed methodology allows increasing the usage of the up and down secondary capacities by almost 13% and 8%, respectively, freeing up 11% of the allocated resources, on average.