雷击与短路故障的S变换特征量识别方法

Identification Method of Lightning Stroke and Short-circuit Faults Using S-transformed Characteristics

输电线路落雷后雷电冲击干扰超高速保护动作。基于行波特征区分雷电冲击与短路故障有一定局限性,提出一种利用母线电压信号特征识别雷击与短路故障的新方法。以IEEERBTS-6标准测试系统为仿真对象,对不同雷击情况以及短路故障进行了仿真,验证了该算法的正确性和有效性。检测到的母线电压进行S变换,提取S变换时频等值线和幅值包络向量,根据是否含高频分量和等值包络向量的修正一阶中心矩的正负,直观准确地实现类型识别,并对特征提取和识别算法进行研究。它利用现有电能质量监测装置检测的信号进行识别,为通过母线电压波形辨识雷电冲击与短路故障提供了新方法。

The ultra-high-speed protection of the power transmission system may be interfered by lightning strokes on lines. It is limited to distinguish the lightning stroke and the common short circuit fault based on the current traveling-waves. We proposed a new method to distinguish the lightning strikes and common short-circuit faults on the basis of the characteristic of the bus voltage signals using S-transform. Through extracting the feature of the voltage signal using time-frequency contour and amplitude envelope vectors by S-transform, an idiographic method for identification of the three types of transient processes was proposed. If there is high frequency component in the voltage signal, the transient process is caused by lightning stroke. If the modified first order central moment BF〈0, there is fault, and if BF〉0 there is not fault. According to the S-transformed characteristic of bus voltage the different transient type can be identified exactly. The methods of both feature extracting and recognition algorithm were proposed also. The IEEE RBTS-6 as the standard testing system was used to illuminate the run-of-mill principle through the PSCAD/EMTDC. The simulation results indicate that the proposed method is effective with reasonable accuracy and its accuracy is not affected by fault types, transient resistance condition and fault location. The instrument of the power quality can be equipped on the system to evaluate the wave of the bus voltage, this paper provide the basic theory to distinguish the lightning strikes and the short-circuit fault through the voltage wave observed from the power quality instrument.