格尔木光伏电站送出线路零序保护异常动作分析

Analysis of Zero-Sequence Protection Action Anomaly on Golmud PV Power Plant Transmission Line

青海格尔木某50 MW光伏电站两回35kV送出线路出现零序电流异常现象。根据该电站送出系统接线形式,结合现场调研情况,建立基于ATP-EMTP光伏送出系统仿真模型,研究线路间互感对各相电流分布的影响。研究发现,在光伏电站两回送出线路两端各并列于同段母线情况下,若线路间距较近,线路间的感应作用将较大程度改变相电流分布,进而产生较大的零序电流,现场增功率试验结果证明了上述结论。在调整两回线路间距并严格按照品字形排列后,两回35kV线路零序电流大幅降低,线路送出恢复正常。

Some zero sequence current anomalies occurred in two-circuit 35kV transmission line of a 50MW PV power plant in Golmud, Qinhai. According to the plant design drawings and on-site investigation, this paper established the dispensing system simulation model based on ATP-EMTP, studied the impact of mutual in- ductance between lines on current distribution in each phase. When both sides of two parallel lines are tied at the same bus segment respectively, we found that if the line spacing is closer, the line between the induction of a greater degree of phase changes current distribution so that it will produce large zero-sequence current. This finding is proved by on-site increasing-power test. After line spacing adjustment and strict arrangement in a triangle, the zero-sequence current in the two-circuit 35kV lines is greatly reduced and recovered to normal.