Robust subsynchronous damping control to stabilise SSR in series-compensated wind power systems

This study presents a robust subsynchronous damping control (RSDC) to mitigate the subsynchronous resonance (SSR) in a practical wind power system with series capacitor compensations. Firstly, the configuration of the RSDC including the subsynchronous damping calculator and the subharmonic voltage source converter is proposed. Then, the impedance-based network model for the whole system is established and the stability criteria is introduced. Thirdly, to increase the robustness of the proposed controller, its parameters are optimised for the varying operation conditions. Finally, the RTDS-based hardware-in-loop tests with the physically implemented RSDC have fully demonstrated its effectiveness in stabilising SSR under different operation conditions and disturbing scenarios, including the switch-on of series capacitors, ramp-down of wind speed and the variation in the number of online wind turbine generators.