补偿电网增量函数法接地选线原理及应用

Protection and Its Application for Detecting Single Phase Earth Fault Feeder Based on Increment Function Principle in Resonant Grounded Power Distribution System

深入分析了补偿电网单相经电阻接地的现象,利用消弧线圈支路阻抗变化前后的系统零序电压、第j支路零序电流及常态下不平衡电流,定义了零序电流增量函数的概念.建立了增量函数与消弧线圈支路阻抗变化前零序电压百分数和该支路电流变化量之间的关系.构建了零序电流增量函数法接地选线判据,该判据既可用于随动式补偿系统,又可用于预调式补偿系统.研制出基于上述原理的接地选线装置,给出了装置的硬件结构图及软件流程.经1年多的样机现场运行表明,该装置选线准确、可靠.

This paper analyzed single phase-to-ground fault through a resistance in resonant grounded power distribution system. With the zero sequence voltage, the current of the feeder j at the time before the arc-suppression coil impedance changes, and after it changes, the imbalance current and the zero sequence current increment function are defined. The relation between the increment function and the zero sequence voltage percent at the time before the arc-suppression coil impedance changes is found. The criterion based on the principle of zero sequence current increment function for detecting grounded feeder is established. It can be used not only in a dynamic resonant grounded network, but also in a preadjustment resonant grounded network. A device based on the principle mentioned above for detecting grounded feeder was developed. The block diagram of its hardware and the flow of its software were given. For over one-year site operation, it is shown that the device can detect fault feeder accurately and reliably.