当三相低压供电系统零线断线时，用户侧将出现中性点位移电压，可能引起设备及人身安全等事故。论文分析了三相配电系统零线断线时中性点位移电压和负载不平衡度的特征关系。基于零线断线时中性点出现位移电压但没有零线电流的特征，提出了带零线电流闭锁判据的识别零线断线的保护原理，并研究了零线断线保护的布点方案。
When zero line disconnection occurs in three-phase distribution system, a displacement voltage will appear at the neutral point of client, which may cause the equipment and personal safety ac-cident. The relation between neutral point voltage and load unbalance is studied when zero line disconnection occurs in three-phase distribution system. The theoretical analysis shows that: zero sequence voltage appears at the neutral point and there is no zero sequence current when the zero line disconnection occurs. Based on this characteristic, a new method to detect zero line disconnection is proposed based on zero sequence voltage with zero line current blocking, and the layout scheme is studied.
