Damping control strategies of inter-area low-frequency oscillation for DFIG-based wind farms integrated into a power system

This study investigates the inter-area low-frequency damping control strategies of a doubly fed induction generator (DFIG)-based wind farm through oscillation transient energy function (OTEF) analysis. Based on the OTEF descent expressions, the feasibility of damping the inter-area low-frequency oscillation is theoretically analyzed through the active/reactive power control of grid-connected wind farms. Additional damping control strategies with the active/reactive power loop of the DFIG-based wind farm are presented using the feedback signal of the transmission line active power flow based on the power system stabilizer (PSS) control method. Transient simulation on different damping gain coefficients are conducted for justification. Following the OTEF mechanism analysis, an additional fuzzy damping control strategy with the active/reactive power loop is proposed by identifying the oscillation phase and the severity to prevent different damping gain coefficients from affecting the presented PSS damping control method. Transient and dynamic simulation results and comparisons showed that both additional control strategies with the active and reactive power loops of the DFIG-based wind farm can damp the inter-area low-frequency oscillation of the integrated power system. The additional damping control strategy with the reactive power loop can damp the transmission line active power oscillation better than that with the active power loop as well as prevent an increase in the torsional oscillation of the wind turbine shaft. The proposed additional fuzzy control strategy with the active/reactive power loop has better damping performance than the presented PSS control, especially for damping the inter-area low-frequency oscillation.