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Chen W.,Chongqing University | Xia Q.,Chongqing University | Sun C.,Chongqing University | Li L.,China South Grid Technology Research Center
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

The extreme result of insulators contamination discharge is contamination flashover. In order to obtain effective characteristics of contamination discharge, the variation method of fractal was used to extract the fractal dimension of leakage current waveform through a number of laboratory experiments. The differences of leakage current fractal dimension in safety, forecast and danger zones under several contamination degrees were analyzed; and the typical value and the standard deviation of fractal dimension in forecast zone were extracted to predict contamination degrees. Experiments showed that variation characteristics of fractal dimension in different stages of contamination discharge are obvious, and fractal dimension values under different contamination degrees are different. These results can predict the development of contamination discharge and the occurrence of contamination flashover, estimate contamination degrees, and thus provide new methods and valid characteristics for the pre-warning of contamination flashover. © 2011 Chinese Society for Electrical Engineering. Source


Chen G.,Chongqing University | Chen G.,China South Grid Technology Research Center | He J.,Chongqing University | Wu X.-C.,China South Grid Technology Research Center | And 3 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

Hybrid dynamic simulation based on the data from PMU can achieve power system simulation validation with the discrepancy between dynamic simulation results and measured values. This paper proposes a hybrid dynamic simulation validation strategy by using ideal voltage source method. It replaces the external system with ideal voltage source, and then incorporates field PMU data of voltage and phase angle signals into the boundary buses of simulation subsystem. Based on simulation software Matlab/Simulink, four-machine-two-area test system demonstrates the simpleness and validity of the proposed method. Finally, with field PMU data, case studies on CSG generator model show the practical application of simulation validation using ideal voltage source method. Source


Song X.-L.,China Electric Power Research Institute | Wu X.-C.,China South Grid Technology Research Center | Liu W.-Z.,China Electric Power Research Institute | Xu A.-D.,China South Grid Technology Research Center | And 2 more authors.
Dianwang Jishu/Power System Technology | Year: 2010

To meet the increasing demands of HVDC power transmission projects being put into operation and offer accurate dynamic analysis and research manners to operation, design and planning departments of power grids, the two terminal HVDC power transmission models of transient stability simulation programs are researched in depth and a group of new control system models, namely the quasi-steady-state (QSS) HVDC models, for power system transient stability simulation are proposed and added into the PSD-BPA transient stability analysis program that is widely used in China, thus the simulation ways for HVDC power transmission system are improved. In QSS models the proportional-integral modules, which are conveniently to be controlled, are adopted for the control of constant current, constant extinction angle and constant voltage, and the simulation results of main elements, such as current setting, voltage dependent current order limit (VDCOL) and commutation failure at DC inverter side and so on, are more close to the characteristics of actual system. Simulation results show that comparing with HVDC power transmission models originally existing in domestic programs, new QSS models can simulate dynamic behavior of HVDC power transmission systems and the accuracy of transient stability simulation results is improved. Source

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