中性点非有效接地电力系统异名相两点接地短路时的选择性跳闸决策

Selective Tripping Strategy Decision of Two-Point Ground Fault Occurred in Different Phases of Neutral Non-Effective Grounding System

中性点非有效接地系统在发生异名相两点接地短路时,现有的保护配置方案存在着同时切除2条接地线路或不能按希望有选择地切除其中一条线路的问题,为此分析了影响跳闸选择决策的因素,定义了跳闸选择指数的计算公式,该指数综合考虑了影响跳闸选择决策的因素的权重及其量值,提出了基于该指数的选择性跳闸决策方案。通过案例检验了该方案的正确性,证明采用异名相两点接地短路的选择性跳闸方案能进一步提高非有效接地系统的供电可靠性。

When arbitrary two-point ground fault occurred in different phases of neutral non-effective grounding system, there is a trouble that existing protection configuration scheme will cut off both grounded lines simultaneously or one of the grounded lines cannot be cut off selectively as desired. For this reason, the factors influencing selective tripping decision are analyzed and the formula to compute selection index of tripping, which takes the weight and value of the factors influencing tripping selection decision into account comprehensively, is given, and then the selective tripping decision scheme is proposed. The correctness of the proposed scheme is verified by cases and it is proved that adopting selective tripping for two-point grounding fault occurred in different phases can improve the power supply reliability of neutral non-effective grounding system.