【摘要】 零序横差保护是大型水轮发电机的重要主保护之一,不平衡电流是影响其性能的主要因素。本文在分析零序横差不平衡电流的产生原因及影响因素的基础上,指出目前零序横差保护判据存在的问题,并根据当发电机内部结构不对称程度一定时,零序横差不平衡电流与主气隙磁通感应电动势成正比的结论,提出一种以气隙感应电动势为制动量的比率制动判据,并辅以反映负序、零序电流大小及三次谐波比的闭锁判据,该保护能充分发挥其高灵敏度的特点,并考虑了电机内部结构和外部短路两方面因素对横差不平衡电流影响,具有较好的保护性能。更多还原

【Abstract】 Zero-sequence transverse differential protection is one of the primary protections of large hydro-generator,whose unbalanced current is a major factor affecting its performance.Based on the analysis of the causes and influencing factors of the unbalanced current,the problem of its protection criterion is indicated.According to the conclusion that the unbalanced current has linear relation with unbalance degree of gap induced electromotive force when the generator internal asymmetric structure remains unchanged,this paper proposes an new proportional restraint criterion which takes the gap induced electromotive force as the restraint quantity.Assisted with the blocking criterion of negative and zero sequence current,and the ratio of the third harmonic,the characteristic of the new zero-sequence transverse protection has high sensitivity.Because of considering the affection of the transverse differential unbalanced current caused by the internal structure and external electrical short circuit,the protection has excellent performance.更多还原