Research on integrated control strategy of doubly‐fed induction generator‐based wind farms on traction power supply system

Abstract

With the large-scale construction of high-speed railway and wind farms, the traction power supply system (TPSS) and wind farms are connected through the power system. The three-phase unbalance of grid voltage caused by the TPSS will seriously affect traditional wind farms’ operation control. Considering the TPSS and wind farms are connected to the power system's public point of common coupling (PCC), the wind farm's current control and voltage support strategy are studied. Firstly, aiming to suppress the influence of harmonics and the unbalanced power grid caused by the TPSS, the repetitive controller (RC) is introduced to the current control of the doubly-fed induction generator (DFIG). The vector control strategy based on the combination of proportion integral (PI) and RC is adopted, where the PI controller is used to adjust the average value of DFIG output power and the RC regulator controls DFIG output sinusoidal stator current. Secondly, the wind farm's voltage support strategy is designed to reduce the voltage fluctuation caused by the TPSS's loads. By coordinating three measures of putting in reactive power compensation devices, DFIG working in voltage control mode, and limiting DFIG output active power, the voltage of wind farm and traction station is effectively supported. Finally, a simulation model with the TPSS and wind farm is built to verify the proposed control strategy's effectiveness.