A Feature Enhancement Method for Operating Sound Signal of High Voltage Circuit Breaker Based on VMD-Wavelet Threshold

It is feasible to use the sound signal generated in the process of opening/closing operation of high voltage circuit breaker (HVCB) to diagnose its mechanical fault. However, the acquisition of sound signal is easily interfered by external noise, which affects the accuracy of fault diagnosis. In order to solve this problem, a variational mode decomposition (VMD) combined with wavelet threshold is proposed to enhance the feature of the operating sound signal of HVCB. Firstly, the sound signal is decomposed adaptively by VMD, and three frequency band components of the sound signal are then obtained. Then, by analyzing the characteristics of noise signals, appropriate threshold is selected to denoise each frequency band signal by wavelet threshold. Finally, the denoised frequency band components are reconstructed to obtain the denoised sound signal. The fault simulation test results show that the proposed method can effectively remove the noise from the operation sound signal of HVCB, and can highlight the fault feature. The noise reduction effect is better than other methods, which has good practicability.