综合暂态与工频信息的谐振接地系统小电流接地故障选线

对于谐振接地系统,利用工频电流的小电流接地故障选线方法不再适用,而受现场普遍存在的电压互感器/电流互感器接线极性反接问题影响,利用暂态电流极性比较与暂态无功功率方向的选线方法也易出现误选。文中在分析过补偿方式谐振接地系统中接地故障暂态与工频零序电流/无功功率分布差异的基础上,提出两种综合利用故障暂态与工频分量的全信息量选线方法,即:与任一其他线路暂态零序电流极性关系与工频零序电流极性关系均不一致的线路为故障线路;或暂态无功功率与工频无功功率流向不一致的线路为故障线路。两种方法均可有效避免因电压互感器/电流互感器接线极性反接或不确定造成的误选,扩大了对现场条件的适用性,提高了选线可靠性。仿真与现场数据验证了算法的有效性。

Faulty Feeder Identification Based on Combined Transient and Power-frequency Components in Resonant Grounded Systems

The power-frequency component is no longer suitable for faulty feeder identification in a resonant grounded system. Influenced by the incorrect polarity connection of voltage transformer and current transformer, faulty feeder is apt to result using feeder identification based on transient current polarity or transient reactive power direction comparison. The distribution differences between transient and power-frequency current as well as transient and power-frequency reactive power for single-phase earth fault in the compensated system are analyzed, based on which, two faulty feeder identification methods based on combined transient and power frequency components are proposed. A faulty feeder is one with a polarity different from that of both the transient zero sequence current and power frequency zero sequence current of healthful feeders, or, a feeder is identified as a faulty one if its transient reactive power and power-frequency reactive power have different directions. The proposed methods have fairly good faulty feeder identification reliability for their ability of avoiding incorrect polarity connection of voltage transformer and current transformer. The feasibility of the new methods is verified by both digital simulation and field test data.