Dynamic series suppression strategy for sub-synchronous oscillation in DFIG-based wind farms connected to series-compensated network

When sub-synchronous oscillations occur in the doubly fed induction generator-based wind farm connected to series-compensated transmission network, the transient behaviors are related to the operational conditions, including the number of online turbines, wind speed, level of series compensation, and control parameters. This paper proposes an adaptive damping device for sub-synchronous oscillations and its control strategy, which addresses suppression requirements under time-varying operational conditions. Unlike in conventional methods, this device is connected in series to transmission line. Suppression control is automatically activated when sub-synchronous oscillations are detected. Furthermore, the proposed strategy behaves as controlled voltage source that is only effective at sub-synchronous frequencies and does not affect normal operations. The effectiveness of the proposed strategy is validated through simulations of the Guyuan wind farm in PSCAD. Results demonstrate significant sub-synchronous oscillation suppression effects in different operational cases, especially those triggered by the interaction between the series-compensated capacitor and the converter controller.