采用零序功率绝对值构成反时限零序电流保护的方案探讨

Research on inverse time current relay based on the absolute value of zero-sequence power

零序电流保护范围会因系统运行方式的变化而伸缩,电网中短线路不断出现,使前后级零序电流保护配合很困难,导致零序反时限过流保护的出现。该文进一步提出采用零序功率(U0×I0)绝对值构成的零序反时限保护,使短路点前后级保护的反时限差别更为扩大,各级反时限附加的固定时间级差大为缩短,对系统运行方式变化具有更强的自适应能力。采用零序功率绝对值构成的零序反时限保护,有利于后备保护的快速响应,对提高零序电流保护的灵敏度和缩短动作时间都具有重要意义。该文还对零序功率反时限继电器构成的原则进行了深入探讨。

The protective zone of the zero-sequence current depends on the variety of parameter of electric power system. The widely used short transmit lines makes it difficult for the zero-sequence current relay to be matched well, which leads to the emergence of inverse time current relay. This paper presents a method by use of the absolute value of zero-sequence power （U0×I0） for achieving inverse time zero-sequence current relay. The method enhances the inverse time for the fault point, and the attached fixed time for each step of the inverse time is largely decreased. Moreover, the method is more suitable for the variation of the operation of electric power system. The inverse time current relay based on the absolute value of zero-sequence power is good for the quick response of the back-up protection and provides significant importance for improving the relay sensitivity and shortening the operating time of protection. Several principles based on this method are discussed in detail, which may provide valuable guides for researchers and manufacturers.