Authors: Chao Tang RuiJin Liao George Chen LiJun Yang
Publish Date: 2011/01/22
Volume: 54, Issue: 5, Pages: 1315-1324
Abstract
As the ultra high DC voltage grid comes into an important stage in the ‘Twelfth Fiveyear Plan’ of China the requirement on the operation safety of power equipment needs to be improved Oilpaper insulation plays a significant role as the main insulation material of many key power equipments The space charge behaviors of oilpaper insulation not only affect the dielectric strength but also relate to the stability and security of power transmission facilities Until now the research on the space charge behaviors of oilpaper insulation remains on the stage of objective description and phenomenon explanation thus it is very urgent to make some feature extractions on the test results in order to further investigate the DC space charge behaviors of oilpaper insulation In this paper based on the large numbers of test data in the first stage data mining and feature extractions were performed on the DC space charge behavior of oilpaper insulation The variation laws of some key characteristic parameters obtained in different experiment conditions such as the total charge injection amount apparent charge mobility and trap energy distribution were analyzed In addition the distribution of trapping level inside oilpaper was calculated by using the PEA test results based on the mechanism of the isothermal decay current which realized the approximate calculation of trap depth by charge decay characteristics What’s more the exponential injection and decay equations of DC space charge changing with time were acquired for the first time and the physical meanings of related parameters were defined This has laid a foundation for the prediction and simulation of space charge in the oilpaper insulation
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