一种振荡中对称性故障的快速识别方法

A new method to rapidly identify the symmetrical fault occurring during power swings

距离保护要求在系统发生振荡时快速闭锁保护,在振荡中发生对称性故障时快速开放保护,如何快速识别振荡中的对称性故障是距离保护的难点。论述了电力系统振荡和振荡中发生对称性故障的电气量特征,提出了一种振荡中对称性故障的快速识别方法。理论分析证明,系统振荡和发生对称性故障时的Ucosφ波形特征有显著差别,且在短时间内就能得到足够的分辨率。通过Ucosφ波形特征识别,不仅能在系统发生振荡时快速检测出振荡,闭锁距离保护;而且能在振荡中发生对称性故障时,快速开放距离保护。该方法物理意义明晰,计算方法简单,判别延时短,判定条件不受系统参数、故障时刻、故障位置等因素的影响。

Distance protection is required to rapidly block protection when detecting power swings and rapidly unlock protection when the symmetrical fault occurring during power swings. It is difficult to rapidly identify the symmetrical fault during power swings. In this respect, this paper discusses the electrical characteristics of power swings and symmetrical fault during power swings, and brings forward a new method based on Ucos waveform characteristics to rapidly identify the symmetrical fault during power swings. The paper proves that the difference of Ucos waveform between power swings and symmetrical fault is clear and adequate resolution can be obtained in a short time, so this method can quickly detect power swings when they occur and block the distance protection. Besides, it can also unblock the distance protection as soon as the symmetrical fault occurs during power swings. This method has a clear physical meaning, simple calculation, short identification delay and no relation with system parameters, fault moment, and fault location.