Seamless Electro-mechanical Frequency Response Control of Wind Turbine Generator Across a Wide Rotor Speed Operating Range

The high penetration of wind energy into the power system requires the provision of frequency response to maintain frequency stability. Due to the intermittent driving force and electro-mechanical decoupling design of the full-scale power converter, the frequency response provided by the wind turbine is quite limited. The existing frequency support strategies must navigate trade-offs between delivering adequate frequency response power and maintaining wind turbine stability following support. This paper proposes a seamless electromechanical frequency support strategy that integrates Virtual Capacitor Control (VCC) with mechanical adaptive droop control. The approach aims to improve system frequency response while maintaining stability in both electrical (voltage) and mechanical (rotor speed) subsystems of the WT. The operational concept and proposed control strategy were validated using MATLAB-/Simulink software. The results demonstrate that the proposed strategy effectively supports system frequency during abrupt power imbalances, while maintaining stable wind turbine operation and reducing the stress on the thermal generator.