乒乓式励磁绕组接地保护方式的改进与分析  

Improvement and Analysis on Ping-Pong Type of Ground Protection for Field Winding

作　　者：张侃君[1] 尹项根[1] 陈德树[1] 

机构地区：[1]电力安全与高效湖北省重点实验室(华中科技大学),湖北省武汉市430074

出　　处：《电网技术》2007年第12期28-32,41,共6页Power System Technology

摘　　要：针对乒乓式接地保护在发电机处于空转或停机时无法对励磁绕组接地故障进行检测的问题,提出给励磁绕组注入一个直流电压,并将开关切换回路接在该电压两端的改进方案,给出了该方案的原理和保护动作判据,对接地电阻计算方法、切换回路元件参数和切换周期的选取等问题进行了分析。仿真试验结果表明改进方案的精度和灵敏度可以满足实际运行需要。通过采样冗余算法计算接地电阻可有效降低采样值坏数据以及非稳态直流工况对保护精度的影响。Current ping-pong type of field winding ground protections cannot detect grounding fault of field winding while generator is in free-running operation or shut down. To remedy this defect, the authors propose an improved scheme for ping-pong type field winding ground protection, that is, a DC voltage is injected into field winding and switching-over circuit is connected in parallel with the injected voltage. The principle of this improving scheme and the criterion for protection action are given; several problems such as the calculation method, of grounding resistance, the selection of parameters in switching-over circuit and that of switching-over period are analyzed. Simulation results show that the accuracy and sensitivity of the improved scheme can meet the requirement of practical operation. By means of calculating grounding resistance by sampling redundant algorithm, the affects of bad sampled data and non-steady DC operating condition on protection accuracy can be effectively reduced.

关 键 词：励磁绕组接地保护 灵敏度 采样冗余算法 电力系统 

分 类 号：TM772[电气工程—电力系统及自动化]