Mitigation of subsynchronous control interaction in DFIGs using active disturbance rejection control

Recently, a new type of subsynchronous oscillation (SSO) has occurred in doubly-fed induction generator (DFIG)-based wind farms. This oscillation is also called the subsynchronous control interaction (SSCI), which is mainly caused by the interaction between the transmission series compensation and the DFIG controller. Therefore, the oscillation frequency of the SSCI is susceptibly impacted by DFIG operating conditions, which presents major challenges to conventional mitigation strategies. To solve this problem, a grid-connected series-compensated DFIG-based wind farm is established, and the formation process of the SSCI is analysed. The strategy of active disturbance rejection control (ADRC), which can automatically estimate and compensate for the total disturbance of the system in real-time, is introduced into the rotor-side converter to mitigate the SSCI in the DFIG. ADRC is designed based on dynamic parameter tuning and chaos optimization. Finally, a detailed model-based time-domain simulation is conducted to evaluate the performance of the proposed optimized ADRC (O-ADRC) compared to conventional virtual impedance and ADRC. The simulation results show that O-ADRC can effectively mitigate the SSCI under different operating conditions and provide sufficient damping for the DFIG-based wind farms.