Research on Sub-Synchronous Oscillation Suppression Strategy of Direct-Drive Wind Turbine Based on Fuzzy Active Disturbance Rejection Control

Abstract

For the sub-synchronous oscillation (SSO) phenomenon that occurs during the grid-connection process of direct-drive permanent magnet wind turbine (D-PMSG), the traditional PI controller is less effective. For this reason, this paper proposes a SSO suppression strategy based on a fuzzy active disturbance rejection control (fuzzy-ADRC). The strategy replaces the PI controller with ADRC by optimising the control structure of the wind turbine grid-side converter and combines the fuzzy algorithm to self-tune the ADRC parameters and dynamically adjust the nonlinear error feedback coefficients to cope with the complexity and uncertainty of the grid-connected wind power system. The simulation results show that fuzzy-ADRC can effectively suppress the SSO within 0.25 s, which is significantly better than the traditional PI controller (unable to suppress) and SSDC (suppression time of 0.3 s), and the suppression time is shortened by 0.75 s compared with the sliding mode control (suppression time of 1 s). In addition, it can maintain system stability under different string complement levels and different wind speeds as well as under system faults and grid disturbances.