Comprehensive Coordinated Control Strategy of PMSG-Based Wind Turbine for Providing Frequency Regulation Services

A high proportion of wind energy in modern power system requires wind turbines (WTs) to provide frequency regulation services. In this context, this paper proposes a comprehensive coordinated control strategy of permanent magnet synchronous generator (PMSG)-based WT for providing an inertial response and primary control. First, a DC-link inertia control is proposed for providing virtual inertia by using the electrostatic energy stored in the DC capacitor, and the key parameters that affect the virtual inertia provided by this control are discussed in detail. Moreover, in order to provide more virtual inertia, a virtual capacitor control (VCC) strategy is proposed. With the VCC strategy, the rotor-side converter (RSC) can provide a virtual capacitance much larger than the actual DC capacitance and supply fast and transient extra power support by using the WT's rotor kinetic energy, in a similar way with the synchronous generator (SG) inertial response. Power-frequency droop control is adapted to allow WT to provide primary control service by using the WT's rotor kinetic energy. Furthermore, the virtual inertia constant of the proposed strategy is analytically derived. Finally, the simulation results in PSCAD/EMIDC are presented to verify the effectiveness of the proposed control strategy.