Optimal Over-Frequency Droop Control for DFIG-Based Wind Farms Under Unreliable Communication

Nowadays, high penetration of wind power is integrated into power grids, and WTs usually adopt the MPPT algorithm to maximize power output, which decouples the rotor speeds of wind turbines (WTs) and system frequency. Therefore, WTs cannot provide frequency support like conventional generators. To that end, especially avoiding WTs aggravating excessive power generation during over-frequency events, optimal droop control is proposed to reduce power output by fully utilizing WTs' own potential in accelerating rotors. Due to unreliable communication in a wind farm, a game theory-based distributed rotor kinetic energy optimization model is developed to obtain the ideal WT rotor speed and power reduction. Next, the optimal droop gains for WTs are designed to be proportional to their ideal power reduction. Then, not only the frequency support capability of WTs is fully activated, but also as much wind power as possible will be stored as kinetic energy into the accelerated rotor blades. Finally, the effectiveness and rationality of the proposed control are verified in MATLAB and DIgSILENT.