Multi-Scale Analysis and Pattern Recognition of Ultrasonic Signals of PD in a Liquid/Solid Composite of an Oil-Filled Terminal

Abstract

In order to analyze the partial discharge (PD) characteristics of a liquid/solid composite medium in an oil-filled submarine cable terminal; we have designed five discharge models including needle-plate, plate-to-plate air gap, surface, slide-flash and suspension potential. At the same time, the ultrasonic signals of PD have been extracted through the typical fault model research platform of oil-filled submarine cable equipment. First, we use SureShrink threshold wavelet denoising to suppress the ultrasonic signal noise. Secondly, through the multi-scale analysis of the signal, the energy distribution maps of five different types of PD are obtained; the analysis found that needle-plate discharge, suspension discharge, and slide-flash discharge have better resolution; and plate-to-plate air gap discharge and creeping discharge have similar characteristics and are not easy to distinguish. Finally, we designed six characteristic parameters of the ultrasound signal, and screened three feature quantities by a back propagation (BP) neural network to distinguish between plate-to-plate air gap discharge and surface discharge. In summary, the method of combining multi-scale analysis and neural networks is used to distinguish the five discharge types by extracting the characteristic values of the characteristic signals.

Intelligent recognition of acoustic emission signals from damage of glass fiber-reinforced plastics

“…33,34 The accuracy was 96% when the characteristic parameters extracted by wavelet decomposition were used for BPNN. 35 In this work, the feature vector obtained by wavelet packet decomposition was used as the input parameters of BPNN, and the recognition accuracy reaches 97.5%. Meanwhile, the number of iterations to achieve the target error was also significantly reduced.…”

The Attenuation and Propagation Law of Ultrasonic Wave in UHV Gas Insulated Line

“…With the development of discharge, the expansion area returns to the original volume. Because of the volume change of the partial gas, the density of the gas changes instantaneously, thus forming the ultrasonic pulse, including longitudinal wave (LW), transverse wave (TW) and surface wave (SW) [24].…”