双馈风电场联络线不对称接地故障测距方法研究

Research on location method for asymmetrical grounding fault in the tie line of DFIG wind farm

受并网方式、运行控制策略等因素的影响,双馈风电场联络线发生不对称接地故障时表现出独特的序阻抗特性,传统故障测距方法难以适用于风电场联络线故障测距。研究双馈风电场整体等值阻抗特性,对风电场联络线故障电流特性和风电场侧的等值序阻抗特性进行仿真分析;基于双馈风电场侧零序等值阻抗的稳定性,提出一种基于系统零序网络的双端测距方法。仿真结果表明:该方法不受过渡电阻和双馈风电场运行方式的影响,适用于各种不对称接地故障,测距精度高。该距离保护方案的整体性能明显优于传统距离保护方案,可较好地满足工程应用要求。

For the asymmetric grounding fault in tie line of DFIG, special characteristics of sequence impedance are appeared due to the grid-connection mode and control strategy of DFIG etc. The traditional fault location method can’t be applied to the wind farm tie line. Firstly, the equivalent impedance characteristics of DFIG were researched in this paper. Furthermore, the sequence impedance characteristics of DFIG and the short circuit current characteristics of the wind farm tie line were simulated and analyzed. And then, based on the stability of zero-sequence equivalent impedance at the wind farm side, a novel double-terminal fault location method based on system zero sequence network was proposed. The simulation results show that the method is immune to the transition resistance and the operation mode of DFIG. It is suitable for various asymmetrical grounding faults with high fault location accuracy. The overall performance of the distance protection scheme is superior to the traditional one, which can meet the engineering application requirements.