Fuzzy Adaptive Frequency Support Control Strategy for Wind Turbines With Improved Rotor Speed Recovery

With the large-scale integration of wind power, the frequency stability of the power system is facing a significant challenge due to the wind power generation system typically operating in maximum power point tracking (MPPT) mode. Traditional frequency support control methods for wind turbines (WTs) do not consider the state of WTs and the frequency changes simultaneously. This article proposes a fuzzy adaptive frequency support control strategy for WTs with improved rotor speed recovery. Based on fuzzy logic control, the proportional gain is adaptively adjusted using the rotor speed and frequency deviation to support the grid frequency. It can fully utilize the frequency support capability of WTs with more available rotor kinetic energy while averting the over-deceleration of WTs with low rotor speed. Moreover, as the frequency deviation increases, the output power of WTs is increased by a larger proportional gain to alleviate the excessive frequency degradation. In response to the shortcomings of traditional rotor speed recovery methods, an improved rotor speed recovery method is presented by integral control, which can restore the rotor speed in stages without affecting the frequency support performance of WTs and can avoid secondary frequency drop (SFD). Simulation results verify the effectiveness of the proposed scheme.