平行线在弱电强磁的影响下,相邻线接地故障时可能会引起本线零序方向纵联保护的误动.文中分析了目前克服弱电强磁所采取的解决方案,指出消除零序方向元件比相电压中零序互感电压是防止零序方向保护误动的一种有效手段.根据上述原理,提出了2种新型零序方向保护方案.考虑零序电压与母线相电压受到相同的零序互感影响,引入非故障相电压差、零序电压与故障相电压之差2种电压作为比相参考电压,从而形成不受零序互感影响的零序方向保护判据.PSCAD/EMTDC的仿真分析表明,文中提出的新保护方案在平行线弱电强磁时能保证可靠不误动.%Under the impact of parallel lines with magnetically strong and electrically weak connection, the false tripping of the league zero-sequence directional protection happens when ground faults occur on another line of the parallel lines. The current solution methodologies are analyzed. This problem is caused by the zero-sequence mutual potential between two lines. This can be solved by using polar voltages which do not contain zero-sequence mutual in zero-sequence directional protection. Based on this principle, two novel methods of zero-sequence directional protection are proposed using non-fault phase voltage difference ae well as zero-sequence voltage and fault phase voltage difference, thus the zero-sequence directional protection criteria are formed without the impact of zero-sequence mutual inductance. The feasibility of new zero-sequence directional protection schemes are verified by PSCAD/EMTDC simulations.
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