This paper investigates the stator circulating current characteristics under the stator interturn short circuit fault, and the effects of the parameter development on the circulating current. The air-gap magnetic flux density was firstly deduced, based on which the electromotive force ( EMF) difference between the two parallel branches was obtained. Then three conditions were taken account to study the circulating current characteristics. Also, the effects of the parameters' development including intensifying of the interturn short-circuit, the increment of the winding-asymmetry between the two branches, and the rise of the exciting current on the circulating current were investigated. Finally, experiments were done on a SDF-9 fault simulating generator to verify the theoretical analysis. The research shows that there are 1st and 3rd circulating currents produced in the parallel branch loop when the interturn short circuit occurs in only one branch or asymmetrically occurs in the two branches. Moreover, the increment of the asymmetric short circuit degree between the two branches and the rise of the exciting current will both make the circulating current increase. However, there will be no circulating current if the two branches have the same short circuit degrees, no matter how seriously the short circuit develops or how much the exciting current is increased.%分析了汽轮发电机定子匝间短路故障下的并联支路环流特性,以及故障参数发展对环流特性的影响.对故障时的气隙磁密进行了推导,得到两条并联支路电势差表达式,分3种情况对并联支路的环流特性进行了分析.分析了短路程度加剧、两条支路有效匝数差增大、励磁电流增大等故障参数发展对环流特性的影响.实测了SDF-9型故障模拟发电机在3种不同匝间短路情况下的环流信号,实验结果与理论分析基本吻合.研究表明,当单条支路短路或两条支路不对称短路时,并联支路内部将产生基波与三次谐波环流,且环流数值将随短路不对称程度加剧或励磁电流增大而增大;当两条支路对称短路时,并联支路内部不产生环流,且不论短路如何发展、励磁电流如何增大,环流数值不变.
展开▼
