Design Of Single-phase Ground Fault Line Selection And Positioning Scheme For Small Current Grounding System Based On Evidence Theory

At present,the small current grounding system is widely used in 35 kV and the following medium and low voltage distribution networks in China,with its incomparable power supply reliability and flexibility.According to the actual operation situation statistics,the system single phase to earth fault occurrence rate is high,accounting for more than 80%.When the small current grounding system single-phase grounding fault occurs,the ground running for a long time is easy to develop into two or more ground,arc grounding will cause over-voltage in the whole system,safe operation,endanger the system.endanger the safety of the system operation,therefore,how to quickly and accurately remove the fault line,has important significance for the operation of the system..However,on the one hand,the complex scene environment,diverse feeder structure and inherent connection mode,and many other factors,the fault information collection,testing is rather large,difficult and poor accuracy of sampling data.On the other hand,the current line selection algorithm and the application of positioning methods have certain limitations,cannot adapt to a variety of conditions.For small current grounding system,when the single-phase grounding occurs,the failure process is divided into transient process and steady state,This paper analyzes the characteristics of these two kinds of process information,and based on this,in view of the existing routing algorithms and positioning methods were compared respectively.The respective advantages and disadvantages and applicable occasions were analyzed and summarized in this paper,which based on information fusion theory framework,designing the comprehensive line selection scheme based on evidence theory.On this basis,the comprehensive utilization of wavelet transform and pattern recognition,based on the C type of traveling wave fault location and location scheme.Finally,for the design of fault line selection and location scheme,in PSCAD platform to build simulation model of the data,and implementing an interface with MATLAB/SIMULINK,to conduct a cross-platform joint simulation study.The simulation results show that the scheme of line selection and location,can quickly and accurately locate the fault point with high accuracy and reliability,has a good prospect of engineering application.