A Novel Method for Mitigating the SSO of DFIG Based on Active Disturbance Rejection Controller

The interaction between the controllers of doubly-fed induction generators (DFIGs) and series-compensated lines may cause subsynchronous oscillation (SSO). In an analysis of the cause of SSO, it is found that the proportional integral (PI) controller of the current loop of the rotor-side converter (RSC) plays a leading role and amplifies the disturbance. Accordingly, this paper proposes a novel mitigation method that replaces the PI controller of the current loop of the RSC with active disturbance rejection controller (ADRC). The ADRC method can estimate and compensate for change in the rotor current caused by the rotor subsynchronous current in real time, maintaining a constant rotor current, eliminating the effect caused by the disturbance and effectively mitigating the SSO phenomenon. Finally, a simulation model based on a real wind farm is built in PSCAD/EMTDC, where the proposed mitigation method is tested under different operating conditions to ensure the system stability. The results show that the effectiveness of the proposed mitigation method and the ADRC is superior to the PI controller in terms of adaptability to changeable operating conditions.