Application of Complex Wavelet Transform to Suppress White Noise in GIS UHF PD Signals

During online partial discharge (PD), ultra-high-frequency (UHF) detection of gas-insulated switchgear (GIS), obtaining acceptable levels of sensitivity, still continues to remain a very challenging task, primarily due to strong electromagnetic interference (including white-noise, random, discrete spectral, and stochastic pulses). As white-noise interference stands in the breach existing in GIS PD UHF detection inevitably, the available suppression methods are unsatisfactory. According to the feature of white noise, the Daubechie´s complex wavelet is constructed. Through the simple information (SI) and combined information (CI) of the complex wavelet transform (CWT), the denoising method of simulation signals and field signals of PD UHF is studied by the authors. In view of the estimation parameters, the results manifest that white-noise in GIS PD UHF signals can be suppressed effectively by the SI and CI of the CWT.