Research On Fault Line Selection And Location Based On Wavelet Transform And PSO Algorithm

At present,small current grounding system is mainly used in medium and low voltage distribution network in China.The frequency of single-phase grounding fault in this system is higher.Because the current is smaller after the fault and there is no obvious fault features,it is difficult to detect it effectively.Many scholars have studied single-phase grounding fault line selection in small current grounding system.Although some achievements have been made,it is still has difficulty to realize line selection accurately.Therefore,it is of great significance to study the features of single-phase grounding fault in distribution network and to diagnose and locate the fault.In this thesis,the small current grounding system is taken as the research object.Based on wavelet transform and PSO algorithm,in-depth analysis and research are conducted focusing on single-phase grounding fault and fault location.The whole thesis mainly includes the following contents:1)In this thesis the features of single-phase grounding fault in small current grounding system is analyzed to lay a foundation for subsequent fault line selection and location.2)The line selection method of single-phase grounding fault is studied.The simulation results of line selection based on amplitude phase comparison method,zero sequence admittance method and wavelet analysis method are compared and analyzed.In view of the advantages of wavelet analysis method in neutral point ungrounded system and arc suppression coil grounding system with higher sensitivity,the single-phase grounding fault line selection method is selected.3)The intelligent algorithm is used to study the fault location in small current grounding system.The PSO algorithm,ant colony algorithm and immune algorithm are simulated and compared,and the fault location based on PSO algorithm is proposed.PSO algorithm transforms the fault location problem into a function optimization problem to solve,and uses MATLAB to simulating.The results show that PSO algorithm has higher accuracy and faster convergence rate,and can accurately locate the fault line in the process of optimization.4)Based on wavelet analysis method,the single-phase grounding line selection device for small current grounding is designed,including hardware and software design,to achieve the function of sampling fault characteristic quantity and analyzing the fault.5)Based on PSO algorithm,the feasibility and accuracy of fault location method and PSO algorithm are verified.