Flexible Voltage Source Grounding Based Active Arc Suppression Technique for Large-scale Wind Farm Considering all Collector Lines

Wind farm collector line single-line ground (SLG) fault arcs are difficult to suppress, which severely threatens the safety of wind farm operations. For this reason, an active arc suppression technique based on flexible voltage source grounding is proposed. A composite sequence network model of a wind farm collector line SLG fault is theoretically deduced. The mechanism of the influence of faulted and nonfaulted collector line wind turbine output currents and collector line impedance on fault residual currents is analyzed. By connecting a controllable voltage source in parallel at the neutral point of the wind farm, the amplitude and phase of the positive-sequence equivalent potential (PSEP) of the wind farm are actively searched and calculated, and the faulty phase voltage of the wind farm can be suppressed to zero. Thus, the ground fault current is eliminated, and arc suppression of wind farm ground faults is realized. A large wind farm with a double-fed induction generator (DFIG) is modeled using PSCAD/EMTDC, and various system operating conditions and ground fault conditions are simulated. The results show that the proposed methods can effectively suppress the fault point voltage of wind farm collector lines, reliably eliminate the fault residual current, and achieve grounding fault arc suppression under different operating and fault conditions.