新型偏磁式谐振接地与保护

在系统地研究了偏磁式谐振接地及保护系统的基础上。提出了一种全新结构的偏磁式消弧线圈，它由一个三柱铁心和五个线圈组成，铁心上有两级减小截面的部分，该部分为磁化区。通过中性点注入工频电流可测量电网电容电流，调谐消弧线圈。还提出了增量函数法接地选线判据，它包括针对永久性接地情况的零序电流增量函数法和针对暂态接地情况的零序能量增量函数法。开发出偏磁式谐振接地及保护成套装置，并进行了系统的模拟试验。一年多的现场运行实践表明：消弧设备补偿效果好、增量函数原理接地选线装置选线准确、动作可靠。

NEW RESONANCE EARTH SYSTEM WITH MAGNETIC BIAS AND ITS PROTECTION

Featured in the paper is a systematic study of a resonance earth system with magnetic bias and its protection. A new structure of arc-suppression coil with magnetic bias is presented.It consists of an iron core with three columns and five coils.The cross-section of the two side columns is cut down partly by two grades and the diminished parts act as the area where the magnetization occurs.By injecting current with 50HZ into the neutral point,the capacity current of the network is measured so that the arc-suppression can be correctly tuned. Two pieces of detection algorithms for earth faults named increment function are initially proposed,one of which is zero current increment function used in permanent earth fault and the other is zero energy increment function used in transient earth faults.A set of equipment of resonance earth and protection is developed which has passed the simulation test.It is proved that thearc-suppression with magnetic bias can be effectively used and the equipment based on increment function principle can detect correctly earth faults by over one year test on the power system.