中低压线路速断保护躲涌流的改进措施

Improvement of the line quick-break protection of low and medium voltage system avoiding effect of magnetizing inrush current

针对配有大量配电变压器的配电网中涌流引起线路速断保护误动的问题,进行了仿真研究,分析了中低压线路单端量保护中涌流特性和中低压线路故障特征。借鉴变压器差动保护涌流识别技术,设计了采用涌流识别技术的中低压线路速断保护。改进后的保护能识别手合或重合线路时配电变压器引起的涌流,可靠闭锁速断保护,又考虑了故障时保护的快速动作,兼顾保护的灵敏性、可靠性及快速性。经数模及挂网运行验证,所采取改进措施有效可靠,具有实际应用价值。

Considering the incorrect tripping of the line quick-break protection of low and medium voltage electric distribution network with large number of capacity distribution transformers caused by magnetizing inrush current, we conduct a simulation research, and study the characteristics of magnetizing inrush current and fault features of the low and medium voltage line. Referring the identification methods of the transformer differential protection magnetizing inrush current, we design the line quick-break protection of low and medium voltage system avoiding the effect of magnetizing inrush current. The improved protection can distinguish magnetizing inrush current caused by the distribution transformers when the line is switched on by manual operation or reclosing relay, lock the line quick-break protection reliably, and give consideration to the sensibility, the reliability and the rapidity. The digifax and the test run prove the improvement is effective and reliable, showing a practical application value.