基于站域信息的同塔多回线零序方向保护防误动方法

同塔多回输电线路中一回线发生非全相运行或不对称纵向故障时,同塔同压健全线路的零序方向保护可能因零序电压补偿而误动,同塔混压线路间感应出的零序电压,也可能造成误动。分析了不对称纵向故障及非全相运行时的电气特征及导致零序方向保护误动的具体机理,论述了多种影响因素对误动过程的作用及解决思路,提出了利用站域信息提取线路状态的防误动方法。在同塔同压多回线路中,提出计算零序电压过零点并反向补偿零序电压的方法防止误动,在同塔混压多回线中,提出根据本站信息识别线路故障特征并自动闭锁零序方向保护的方法。采用实时数字仿真器(RTDS)对同塔多回线在不同工况下发生不对称纵、横向故障时健全线路电气量特征及误动过程进项仿真,验证了防误动方法的有效性。

Substation Information Based Method for Preventing Mal-operation of Zero-sequence Directional Protection on Multi-circuit Transmission Lines on the Same Tower

In case of open-phase operation or asymmetric longitudinal fault occurring on one line of the multi-circuit transmission lines on the same tower, the zero-sequence directional protection of healthy lines with the same voltage on the same tower may mal-operate due to the zero-sequence voltage compensation. Zero-sequence voltage induced between the lines on the same tower with mixed voltages may also cause mal-operation. The electrical characteristics of asymmetric longitudinal faults and open-phase operation and the specific mechanism leading to mal-operation of zero sequence directional protection are analyzed. The influence of various factors on the process of mal-operation and the solution are discussed. A method for preventing mal-operation by extracting the states of transmission lines based on substation information is proposed. For multi-circuit transmission lines with the same voltage on the same tower, the method for preventing mal-operation by calculating the cross point of zero-sequence voltage and reversely compensating zero-sequence voltage is proposed. For multi-circuit transmission lines on the same tower with the mixed voltages, the method of identifying the failure characteristics of the lines based on the substation information and automatically blocking the zero-sequence directional protection is proposed. Real-time digital simulator(RTDS)is used to simulate the electrical characteristics of healthy lines and the mal-operation process when an asymmetric longitudinal/latitudinal fault occurs on multi-circuit transmission lines on the same tower under different work conditions. The effectiveness of the proposed method for preventing mal-operation is verified.