风电场送出线中比相式距离保护非故障环路距离元件的误动可能性分析

At Shaanxi Province's Qiushi Wind Farm, a reverse two-phase grounding fault triggered maloperation in the non-fault loop phase comparison grounding distance element. Conventional understanding holds that phase comparison distance protection possesses inherent directivity, making non-fault loop distance element operation theoretically impossible. Consequently, the potential for such maloperation has remained unexplored in existing research. This paper addresses this gap by analyzing the distance protection maloperation incident at Qiushi Wind Farm as a case study. Integrating grid topology analysis, wind farm characteristics, and protection operating principles, we identify the root cause of the maloperation. Our findings are subsequently validated using actual fault recording data. The possibility of maloperation of grounding distance and interphase distance elements under different fault types and different fault locations is discussed. Finally, the above conclusions are extended to the synchronous machine source system. It is found that the phase comparison distance protection of positive sequence voltage polarization does not possess fault phase identification capability. A simulation model is built in PSCAD/EMTDC to verify the above conclusions, and several suggestions are given to prevent distance protection from maloperation based on fault recording.