Combination of pressboard and mineral oil continues to be the choice of materials used as the insulation dielectric media in large transformers.The purpose of the reported study is to investigate the influence of pres...Combination of pressboard and mineral oil continues to be the choice of materials used as the insulation dielectric media in large transformers.The purpose of the reported study is to investigate the influence of pressboard aging on PD(partial discharge) pulse parameters.Ultra wide band(UWB) time-resolved PD pulse measurements were carried out on gas void inside pressboard.The rise rime,full time and width time of PD pulse in different aging degree pressboard are obtained.The result is helpful to better understanding the influence of the aging of pressboard on PD measurement and insulation diagnostics in power transformers.展开更多
This paper expounds the main structure design and function implementation of a provincial power grid relay protection setting calculation integration system. In accordance with the actual features of the relay protect...This paper expounds the main structure design and function implementation of a provincial power grid relay protection setting calculation integration system. In accordance with the actual features of the relay protection setting calculation work, setting calculation system is developed based on the project. For the development and research of integration of setting calculation system, to achieve a certain provincial power grid relay protection setting calculation and the standardization of the operation and management, network and intelligent, is of great significance.展开更多
Temperature and humidity are the main factors that cause the decomposition of Nomex paper widely used as turn‐to‐turn insulation material of mining dry‐type transformers. In this study, for understanding the effect...Temperature and humidity are the main factors that cause the decomposition of Nomex paper widely used as turn‐to‐turn insulation material of mining dry‐type transformers. In this study, for understanding the effect of ambient humidity and thermal aging on the properties of Nomex paper, specimens with the initial moisture content of 7% were aged in the oven for 168, 504, 672 h at 180°C, respectively. After thermal aging, corona discharge experiments of unaged and aged specimens with different aging degrees were carried out at different relative humidity (RH) levels from 10 to 70%. The characteristic parameters of corona discharge, such as the average discharge amplitude and the number of discharges, were measured. Then, the surface conductivity and the surface potential decay rate were measured. The morphology and attenuated total internal reflectance Fourier transform infrared spectroscopy were also analysed for explaining the difference of properties be-tween unaged and aged specimens. The experiment results indicate that the average discharge amplitude decreases with the increase of RH or the deepening of the aging degree of specimens, but the number of discharges shows the reversal tendency. The changes in the physical structure and chemical composition, which is induced by the hydrolysis reaction of Nomex paper, accelerate the surface potential decay and increase the surface conductivity.展开更多
基金Supported by Fundamental Research Funds for the Central UnivcersitiesNational Natural Science Foundation of China (50977075)National Basic Research Program of China(973 Program) (2011CB209404)
文摘Combination of pressboard and mineral oil continues to be the choice of materials used as the insulation dielectric media in large transformers.The purpose of the reported study is to investigate the influence of pressboard aging on PD(partial discharge) pulse parameters.Ultra wide band(UWB) time-resolved PD pulse measurements were carried out on gas void inside pressboard.The rise rime,full time and width time of PD pulse in different aging degree pressboard are obtained.The result is helpful to better understanding the influence of the aging of pressboard on PD measurement and insulation diagnostics in power transformers.
文摘This paper expounds the main structure design and function implementation of a provincial power grid relay protection setting calculation integration system. In accordance with the actual features of the relay protection setting calculation work, setting calculation system is developed based on the project. For the development and research of integration of setting calculation system, to achieve a certain provincial power grid relay protection setting calculation and the standardization of the operation and management, network and intelligent, is of great significance.
基金National Natural Science Foundation of China,Grant/Award Number:51577123。
文摘Temperature and humidity are the main factors that cause the decomposition of Nomex paper widely used as turn‐to‐turn insulation material of mining dry‐type transformers. In this study, for understanding the effect of ambient humidity and thermal aging on the properties of Nomex paper, specimens with the initial moisture content of 7% were aged in the oven for 168, 504, 672 h at 180°C, respectively. After thermal aging, corona discharge experiments of unaged and aged specimens with different aging degrees were carried out at different relative humidity (RH) levels from 10 to 70%. The characteristic parameters of corona discharge, such as the average discharge amplitude and the number of discharges, were measured. Then, the surface conductivity and the surface potential decay rate were measured. The morphology and attenuated total internal reflectance Fourier transform infrared spectroscopy were also analysed for explaining the difference of properties be-tween unaged and aged specimens. The experiment results indicate that the average discharge amplitude decreases with the increase of RH or the deepening of the aging degree of specimens, but the number of discharges shows the reversal tendency. The changes in the physical structure and chemical composition, which is induced by the hydrolysis reaction of Nomex paper, accelerate the surface potential decay and increase the surface conductivity.
