Optimizing Grid-Forming Wind Turbines Share for Frequency Regulation and LOLF Reduction in Modern Power Systems

This paper explores the optimal proportion of grid forming wind turbines (GFM-WTs) necessary for effective participation in frequency regulation during power system disturbances, with the aim of minimizing the loss of load frequency (LOLF) index. To achieve this, the security constrained unit commitment (SCUC) problem is first formulated and then solved to determine the dispatch of conventional and wind power plants. Then a generation unit for failure is selected based on predefined failure and repair rates. Wind turbines are categorized into grid following wind turbines (GFL-WTs), which do not contribute to frequency regulation, and GFM-WTs, which operate slightly below their maximum capacity to provide additional power support when needed. The Hydro-Québec controller is applied to GFM-WTs for frequency recovery. A Monte Carlo simulation is employed to assess the number of events in which the system frequency falls below 49.5 Hz, indicating an unstable power system that leads to load shedding. The optimal percentage of GFM-WTs is determined as the configuration that minimizes the LOLF index. The proposed methodology is implemented on the IEEE 24-bus reliability test system, demonstrating its effectiveness in enhancing frequency stability.