选择性发电机定子单相接地保护方法

在深入分析发电机对地泄漏电流(即3倍中性点侧零序电流与机端出线侧零序电流之差)的基础上,提出了一种通过比较发电机定子单相接地故障时各发电机泄漏电流的大小或方向进行保护的发电机定子接地保护新方法。该方法利用发电机对地泄漏电流的基波分量和3次谐波故障分量,分别判断单相接地点是否在本发电机定子绕组内部,实现100%定子接地保护。EMTP仿真分析表明该保护方法能有效检测定子单相接地故障和准确判断接地故障发电机,适用于各种中性点接地方式,具有鲁棒性强、准确度高等特点。

Selective protection for stator winding grounding faults

Based on the deep study of stator winding phase-to-ground leaking current (three times of the zero sequence current difference between generator neutral and generator terminal),a selective protection for generator stator grounding faults is proposed,which compares the magnitude and direction of the leaking current. It determines if the grounding point is in generator stator winding according to the first harmonic and third harmonic of leaking current to realize 100 % stator grounding protection. EMTP simulative results show that the protection can detect the single-phase grounding fault of stator winding and determine the faulty generator for various neutral-point grounding modes with high robusticity and correctness.