Fault Line Selection Method For Resonant Grounded Power Network Under Multi Information Fusion Technology

About 80% of the power grid fault is caused by the single-phase ground fault.Operation of power grid with fault will threaten the safety of the power grid itself,so fast and accurate detection of grounding fault line is very important for the safe operation of the power grid.It is a popular way to use neutral point via arc suppression coil grounding(also called the resonant grounding)in medium voltage power grid in our country.However,electric current of the fault line in the resonant grounded power grid is influenced by compensation effects of the inductance current produced by the arc suppression,thus making it difficult to correctly reflect the relationship between fault lines and healthy lines.So the selection of fault lines is far more difficult than in other grounding method of power grid.For this kind of power grid,the accuracy of existing fault line selection methods is difficult to meet the actual demand of safe operation of power grid.The application effect of the line selection device is not ideal.Therefore,there is theoretical significance and engineering practical value in studying this kind of single-phase ground fault line selection problems.The characteristics of all kinds of existing line selection methods are deeply analyzed.A line selection strategy that we use many kinds of line selection methods as the basic criterion of foundation of information fusion is proposed.Two aspects characteristics of the constant state and the transient state in the resonant grounding grid are studied.Based on this,we confirm using fault transient information as the main part of line selection method of information fusion.Based on the Matlab7.0/Simulink6.0 simulation platform,the simulation model of ground fault in resonant grounding power grid is designed.Simulation of the ground fault with the ground fault simulation model from the different earth fault condition is processed.The influence of different fault conditions for fault information is also analyzed.An information fusion fault line selection method based on the extension theory is proposed.Firstly,three single line selection methods are proposed as the criterion of information fusion.Using the criterion of composite weight allocation method,make the values determine of each criterion more objective and reasonable.The extension theory is introduced to the selected criterion for information fusion faultline selection aiming to get each line fault's correlation credibility so as to select the fault line.The simulation experiment is conducted by the simulation model and the results have proved the validity and accuracy of the proposed line selection method.Aiming at the problem that the line selection method based on extension theory has poor interpretation in the process of the information fusion.A method of fault line selection based on extension theory and evidence theory is proposed.This method using the extension theory to obtain the basic trust assignment function which evidence theory needs,making the fusion of the fault criterion improved from the sum of the correlation function values to the evidence reasoning process.The information fusion process is more scientific and reasonable.The result shows that the interpretation and accuracy of the improved information fusion method has greatly improved by using the proposed line selection method to process the simulation data.