电动机差动保护误动分析与改进措施

Nalysis of Electrical Motor Differential Protection Misoperation and Its Improvement

对电动机起动过程中差动保护误动原因的分析,一般认为多重因素导致电动机起动时电动机侧电流互感器严重饱和,使二次电流出现畸变失真引起差动保护误动。针对电动机差动保护和电流互感器特点,本文给出了多个解决电流互感器饱和的方案,并结合目前发电厂厂用电发展趋势,提出厂用电流互感器参数选择、二次回路设计等方面需要考虑与保护配合,避免保护发生拒动、误动。

An analysis of differential protection misoperation in electrical motor start-up process suggests that a multitude of factors lead to gross saturation of the motor side current transformer in motor start-up and the distortion in secondary current gives rise to differential protection misoperation. To address current transformer saturation, several solutions were proposed having regard to the characteristics of motor differential protection and the current transformer. In consideration of the service power generation trend at present in power plants, it has been suggested that the service power current transformer parameters and secondary circuit design, among others, shall take into account the coordination with protection in order to forestall failure to trip or misoperation in protection.