距离保护误差特性分析

Error analysis of distance protection

由于CT、PT的测量误差,距离保护在应用于短线路时会带来较为严重的超越问题。分别分析了测量误差对接地距离和相间距离所带来的影响,指出接地距离超越主要由幅值误差引起,相间距离超越主要由相角误差引起。推导出距离保护Ⅰ段适用线路长度与系统阻抗之间的关系,其对于短线路距离保护是否投入具有指导意义。

Because of the measuring error of current transformer （CT） and potential transformer （PT）, the distance protection faces to the overreaching problem when it is used on the short transmission line. This paper analyzes the different influences to ground and inter-phase distance protection and reaches to the conclusion that the ground distance overreaching lies on the amplitude error while the inter-phase one dues to phase-angle error. A relationship between system impedance and the length of line applied zone I of distance protection is derived and it gives guidance for the use of distance protection on short line.