Speed Recovery Strategy of WTG Based on Variable Parameter PI Control

As renewable energy generation continuously replaces the traditional synchronous machine, the inertia of power system decreases, the frequency regulation ability weakens, and the risk of frequency instability increases. Therefore, domestic and foreign scholars have proposed a variety of control strategies for renewable energy generation to active participate in frequency regulation. Due to the limitation of rotor speed, wind turbine generators(WTGs) need to quit frequency regulation to recover the speed after participating in frequency regulation for a period of time, which will lead to secondary frequency drop. However, the existing WTG rotor speed recovery strategies are mainly improved based on fixed conditions, and the actual wind speed changes are less considered. Therefore, a variable parameter PI control method considering wind speed and rotor speed offset is proposed, which can realize the smooth recovery of speed and reduce the influence on frequency secondary drop. Finally, the effectiveness of the proposed method is verified by simulation.