具有防过负荷误动的距离保护新方法

摘要

In allusion to the problem of traditional zone III distance relays can′t identify the line overload and the line fault, this paper specifically analyses the electrical characteristics differences of the overload and the fault in Uφcosφφand the change of phase, then a new method of distance protection zone III preventing overload mal-operation is pro-posed.The method includes two parts:one of them is a method to distinguish phase-to-phase faults from symmetrical overload, which is based on Uφφcos(φφφ+90°-φline )<0.5UNN;the other of them is a method to distinguish single-phase earth fault from unsymmetrical overload, which is based on current asymmetry degree,ARG( U · ·φ2/U 0 ) and ARG · · (Uφ1/U 0 ) (φ=A,B,C) .The implementation scheme of distance protection zone III coping with overload mal-opera-tion is proposed.The method is effective through RTDS simulation verification.%针对事故潮流易造成线路传统距离保护 III 段误动的隐性故障问题，详细研究了过负荷和故障在Uφcosφφ和电压序分量相位等电气特征差异，提出了一种具有防过负荷误动的距离保护III段新方法。此方法包括两部分：基于Uφφcos（φφφ＋90°－φline ）＜0．5UNN的全相过负荷与相间故障识别方法；基于电流不对程度、···· ARG（ Uφ2／U 0）和ARG（ Uφ1／U 0）的非全相过负荷与单相接地故障识别方法。介绍了具有防止过负荷误动的距离保护III段实施方案，并通过了RTDS仿真试验验证。