Analysis and comparison of secondary frequency control reserve activation rules: Pro-rata vs. merit order

This paper investigates the two common activation rules for secondary frequency control, namely pro-rata activation and merit-order activation based on submitted bids. A representative model of power plant and control area is built and then technical and economic comparisons are performed. The study has been done using practical data available to the Swiss TSO, Swissgrid, and one of the German TSOs, TransnetBW.