关于定子接地保护的几个问题  

STUDY ON STATOR EARTH FAULT PROTECTION

作　　者：李玉海[1] 张小庆[1] 徐敏[1] 

机构地区：[1]西北电力试验研究院

出　　处：《电力系统自动化》1999年第11期50-54,共5页Automation of Electric Power Systems

摘　　要：以几次事故为例说明：用“允许接地电流”来决定定子接地保护投运方式是不合理的。对于双水内冷发电机及没有匝间保护的大、中型发电机，其定子接地保护应投跳闸。３次谐波电压型接地保护动作可靠性低的原因是：调整不当，工作环境条件差，回路及继电器本身有缺陷。为提高其动作可靠性，应掌握机组机端３次谐波电压和中性点３次谐波电压的变化规律，改善环境，并及时更换不良的３次谐波电压型保护。发电机中性点经配电变压器接地，降低了定子接地保护的动作灵敏度，对经计算不可能产生过电压的发电机，应将配电变压器换成单相电压互感器（ＴＶ）或消弧线圈。无条件换时，应尽量增加二次侧并联电阻。基波零序电压型接地保护的定值应为５Ｖ～１０Ｖ。Based on the experiences obtained from a cumber of fault analyses, the operation mode can not be determined by permissible ground current. For double-water inner-cooled generator and the large and medium sized generator without interturn fault protection, the stator earth fault protection should act on tripping. Low reliability of 3w based earth fault protection is mainly resulted from improper adjustment, relatively bad working condition and the inherent defects in relay circuit. In order to raise reliability of 3w based earth fault protection, change of Us3 and Un3 with generator stator voltage and load should be measured, working condition should be improved and the protection not working properly should be replaced with new one. Grounding the generator neutral through distribution transformer will decrease sensitivity of stator earth fault protection. For the generator without possibility of over-voltage through calculation, the single phase potential transformer or arc-suppression coils should be used to replace the distribution transformer, if doing so is impossible, resistance of the resistor parallelly connected with secondary winding of distribution transformer should be increased properly, The setting value of 3u0 based earth fault protection should be 5 V～10V.

关 键 词：定子 接地保护 灵敏度 可靠性 双水内冷发电机 

分 类 号：TM311.073[电气工程—电机]