摘要
分析北区供电局发生的10kV馈线单相相继接地、高阻接地故障,指出10kV小电阻(10Ω)接地系统110kV主变压器与10kV馈线零序过流保护定值配合不当时,在以下情况容易造成主变保护越级动作:当两段馈线相继单相接地时,电流、时间叠加造成越级;一馈线单相高阻接地,保护、接地信号未动作,当另一馈线也同一相高阻接地时,电流叠加造成越级;如果主变的零序TA负误差,馈线的零序TA正误差,两者的电流动作值几乎相等。针对上述情况,修改后的定值改善了主变与馈线零序过流保护的配合,解决了相继接地、高阻接地以及零序TA误差造成越级的问题,更好地监视高阻接地。
Several highresistance,sequent singlephasetoground faults in the 10 kV system of Guangzhou Power Supply Bureau are analyzed. It is pointed out that the improper setting of zero sequence overcurrents of 110 kV main transformer and 10 kV feeder protections may cause main transformer protections skip in thefollowing conditions. The fault times and currents are added together when two feeders ground sequentially. The fault currents are added together when one feeder is grounded through high resistance during another feeder is also grounded through high resistance at the same phase while its protection and grounding signal failed to act. The zero sequence currents of main transformer and feeders are almost equal when the main transformer zerosequence CT has negative error and that of feeder has positive error. The modification of settings mayimprove the cooperation between main transformer and feeder protections. The new settings have solved the problems mentioned above.
出处
《电力自动化设备》
EI
CSCD
北大核心
2002年第10期73-75,共3页
Electric Power Automation Equipment
