基于离散小波变换的输电线路故障精准定位

Accurate Fault Location of Transmission Lines Based on Discrete Wavelet Transform

为了提高架空线路和地下电缆组合输电线路发生故障时的定位精度,提出了一种基于离散小波变换(DWT)的输电线路故障定位新方法;通过DWT对输电线路单端测得的瞬态信号进行多分辨率分析(MRA),在低故障起始角情况下,利用线模电流和零模电流检测故障,结合小波模量极大值(WMM)求解从故障点到变电站的行波到达时间,从而对输电线路故障进行精准定位;采用半正弦电压响应的方法克服了采样频率有限和故障起始角低的缺点,运用100 kHz半正弦信号的发送时间与接收导数信号的时间之差计算故障距离;在考虑谐波畸变和故障电阻、接地电阻、故障位置和起始角变化的情况下对所提方法进行测试,结果表明:对于100 km的输电线路,即使在故障靠近总线(<2%)且故障起始角较低的情况下,所提出的方法得到的故障定位误差仅为0.14 km。

In order to improve the fault location accuracy of combined transmission line between overhead line and underground cable, a new method of transmission line fault location based on discrete wavelet transform(DWT) is proposed. Multi resolution analysis(MRA) is carried out on the transient signals measured at single end of the transmission line through DWT. Under the condition of low fault starting angle, the line mode current and zero mode current are used to detect the fault, and the traveling wave arrival time from the fault point to the substation is solved in combination with wavelet modulus maximum(WMM), so as to accurately locate the transmission line fault. The method of half sine voltage response overcomes the shortcomings of limited sampling frequency and low fault starting angle. The fault distance is calculated by using the difference between the sending time of 100 kHz half sine signal and the time of receiving the derivative signal. In view of the harmonic distortion and the changes of fault resistance, grounding resistance, fault location and starting angle, the test results show that for the transmission line distance of 100.0 km, even if the fault location is close to the bus distance of less than 2% under the condition of low fault starting angle, the fault location error of the proposed method is only 0.14 km.