Optimal Short-Term Frequency Support Strategy for Multiple Wind Turbines Based on Synchronous Release of Rotor Kinetic Energy

Upon active power deficiency in the grid causing frequency drop, wind turbines (WTs) can release the stored rotor kinetic energy to provide short-term frequency support (STFS). Unlike synchronous generators (SGs) with synchronous operating characteristics, the rotor speed for multiple WTs during STFS exhibits distinct variations. How to reasonably release the rotor kinetic energy of WTs to maximize grid frequency support is a hot issue in current research. This article proposes an active power complementation control (APCC) to distribute output power based on the proportion of maximum releasable rotor kinetic energy, proves that APCC can minimize maximum frequency deviation (MFD) by synchronously releasing rotor kinetic energy, and reveals the mechanism of cooperative frequency regulation between multiple WTs and SGs. Furthermore, a practical APCC for multiple WTs is designed, encompassing key parameter calculation and rotor speed recovery. The superiority of this method in enhancing grid frequency regulation for WTs is validated via the experiment on the grid dynamic simulation test bench with three WT simulators and the simulation on the IEEE 39-bus power system with three equivalent wind farms.