Study Of The Signal Processing Based On Pulsed Electro-Acoustic Method In XLPE Cable

The Cross-linked polyethylene power cables have been widely used in the transmission and distribution networks underground for its excellent mechanical and electrical performance. However, it will distort the signal the local electric field and the insulating property will be affected due to the accumulation of space charge in the polymer such as XLPE, therefore, it is of great importance that the space charge in insulting medium is studied. Currently, the pulsed electro-acoustic method, which applies to the test of space charge in slice and XLPE cable, is the most widely used among approaches for the measurement of spatial charge, but it is an important issue that how to transform the voltage signal acquired from the PEA method to the accurate spatial charge distribution.Actually, in this article, two factors which could influence the test waveform of PEA method is proposed, the former is about the hardware circuit, its frequency response could lead to overshoot of signal, and the work performance of the piezoelectric crystal sensor and amplifier_will change with the variations in temperature; the latter relates to the spread character of sound wave produced by PEA, including the sound wave attenuation caused by the friction damping and shape of sound radiation, the variation of velocity and amplitude of the sound wave on account of the temperature gradient in the specimen.A set of program is developed for signal processing of the PEA waveform in XLPE cable based on the way of waveform restoration for the influence factor that really matters. The procedure contains three parts, the overshoot recovery module with frequency domain deconvolution method amended with Gaussian function, the attenuation restoration module specific to slice, XLPE cable and XLPE cable in thermal gradient, and the calibration module. And the effectiveness of the proposed approach is validated by instance analysis. It provides elements of data analysis for the study of aging characteristics between insulating material such as XLPE and the spatial charge in it.