基于信号处理的有载分接开关过渡电阻测量方法

Measurement Method for the Transition Resistance of On-load Tap Changer Based on Signal Processing

有载分接开关(on-load tap changer, OLTC)在出厂前和运行维护期间,需利用直流或交流测试装置进行工况检测。OLTC交流测试装置因测量回路阻抗较大,存在过渡电阻信息计算不准确等问题。为此提出以小波变换、傅氏变换、Prony等算法提取采样信号基波分量并以dq坐标变换为核心算法的回路阻抗求解方法。首先利用小波变换对OLTC切换关键点进行辨识,然后对比了傅式算法、Prony算法和最小二乘算法在提取信号基波分量的差异,最后通过dq坐标变换计算得到电路等效阻抗及过渡电阻数值。结果表明,仿真与实测结果基本一致,验证了方法的有效性,而傅式算法计算过渡电阻误差最低,约为104.812 5%。该方法为优化OLTC设备工作参数测量提供了依据,可以为下一步样机开发提供思路。

The on-load tap changer(OLTC) needs to be tested for working conditions by DC or AC source testing device before the ex-factory and during the maintenance period. The OLTC AC test device has problems such as inaccurate calculation of transition resistance and other information acquisition due to the large impedance of the measuring circuit. We proposed a solution method of the loop impedance by using the wavelet transform, Fourier transform, Prony algorithm to extract the base wave component of the sampled signal, and by taking the coordinate transformation of d and q as the core algorithm. Firstly, the key points of OLTC switching was identified by the wavelet transform, and then the differences between the Fourier algorithm, Prony algorithm and the least square algorithm in extracting the fundamental wave components of the signal were compared. Finally, the equivalent impedance and transition resistance of the circuit were calculated by d and q coordinate transformation. The results show that the simulation results are basically consistent with the measured results, verifying the validity of the method, and the error of the transition resistance calculated by the Fourier algorithm is the lowest, about 104.812 5%. This method provides references for optimizing the measurement of the working parameters of OLTC equipment, and can provide ideas for the next prototype development.