Subsynchronous oscillation mitigation strategy based on ADRC for D-PMSGs based wind farm

Recently, the problem that SSO(SubSynchronous Oscillation) caused by the interaction between D-PMSGs(Direct-drive Permanent Magnetic Synchronous Generators) based wind farm and weak AC power grid frequently occurs in western China. To solve this problem, the SSO mitigation strategy based on ADRC(Active Disturbance Rejection Control) is firstly proposed, in which the mechanism of SSO is utilized. In this strategy, the ADRC controller is designed to replace the PI(Proportional-Integral) controller of current inner loop of grid-side converter for D-PMSGs. Secondly, the mitigation mechanism of the ADRC controller is theoretically derived. This ADRC controller can estimate and compensate the real-time impact of D-PMSGs based wind farm integrated in weak AC power grid, and hence can avoid the interaction between D-PMSGs based wind farm and weak AC power grid. As a result, the SSO is expected to be effectively mitigated. Finally, an electromagnetic transient simulation model with both PI and ADRC controllers is built on PSCAD/EMTDC, and the mitigation effect of the two controllers on SSO are analyzed and compared. Simulative results show that the ADRC controller not only effectively mitigates SSO, but also exhibits satisfactory robustness and adaptability. It also proves that the main factor of SSO in D-PMSGs based wind farm lies in the PI controller of current inner loop of grid-side converter for D-PMSGs. © 2020, Electric Power Automation Equipment Press. All right reserved.