弱行波信号的奇异点检测方法

A Novel Singularity Point Detection Method for Weak Traveling Wave Signals

当电压过零附近或者高阻接地故障时行波信号较弱,同时受行波上升沿畸变以及噪声干扰等因素的影响,传统小波检测法的检测结果可能会出现较大误差。为可靠检测到故障行波信号的奇异点,文中提出了一种新的检测方法,即根据推导得出的故障行波波头表达式,并结合高速数据采集装置的实测数据,获取故障行波拟合曲线,依此确定故障行波信号奇异点。通过对输电线路中波头上升沿的特征分析以及母线处分布电容对波头上升沿的影响分析,得出了表征行波波头上升沿的表达式;为增强算法可行性,利用麦克劳林(Maclaurin)展开式推导出了行波波头的间接表达形式。利用该表达式拟合出的行波曲线可确定行波信号的奇异点。仿真结果表明,所提出的检测方法可有效地确定弱行波信号的奇异点。

The traveling wave signals（TWS） are weak when the voltage is near the zero-cross point or the high resistance grounded fault occurs. Besides,they may be distorted and disturbed by noise as well. In such a case,the singularity point of TWS may not be detected correctly with traditional wavelet transformation detection method,so a novel singularity point detection method for weak TWS is proposed. The basic principle of the method is to detect the singularity point with the fitted curve of faulty TWS. The fitted curve is determined by integration of the expression for traveling wave front（TWF） with the real-time measuring data of high-speed acquisition units. After the characteristic analysis of rising edge of TWF and influence on rising edge of TWF caused by distributed capacitance on bus bar,the expression for rising edge of TWF is deduced. Furthermore,in order to improve the feasibility of the algorithm,TWF indirect expression is deduced with Maclaurin expansion. TWS singularity point can be detected from the fitted curve based on the indirect expression. The simulation results show the validity of this method.