长短线悬殊和不平衡电流大时的矿井低压漏电保护分析

通过实例分析说明了零序功率方向原理和零序电流最大原理等传统的漏电保护原理无法实现长短线悬殊和不平衡电流大情况下的选择性漏电保护;提出了一种采用零序电流突变量法实现长短线悬殊和不平衡电流大情况下的选择性漏电保护方案。该方案通过比较各支路零序电流和对应支路固有电容电流来判断是否发生漏电,即如果某一支路的零序电流与固有电容电流相比发生突变,则该支路为漏电支路;如果所有支路的零序电流与固有电容电流相比都没有发生突变,则为总线漏电。实践证明了该方案的有效性。

Analysis of Mine Low-voltage Leakage Protection in Situation of Great Disparity between Long and Short Lines and Big Unbalanced Current

The paper explained that traditional leakage protection principles such as zero-sequence direction relay principle and zero-sequence current's maximum principle are unable to implement selective leakage protection in situation of great disparity between long and short lines and big unbalanced current through analyzing an actual example,and proposed a scheme of selective leakage protection in the situation by use of zero-sequence current's break variable principle.The scheme judges leakage by comparing zero-sequence current with inherent capacitive current of each power line as follows: if zero-sequence current of one power line changes suddenly compared to inherent capacitive current,then the power line would be leakage line;if zero-sequence current of non power line changes suddenly compared to inherent capacitive currents,then main line leakage happens.The application showed the validity of the zero-sequence(current's) break variable principle.