Research On Single-Phase Grounding Fault Location Of Distribution Network Based On Multi-source Information

With the continuous development of power system and the increasing load,the demand of power supply reliability is higher.As the end of power system,distribution network has the characteristics of complex topology and more branch lines.It is a multi generating area of power system fault,among which single-phase ground fault accounts for more than 75% of the total number of distribution network faults.In addition,in order to improve the reliability of power supply,the neutral point non effective grounding operation mode is widely used in distribution network,which leads to the weak fault characteristics and is not conducive to fault feature analysis and fault location when single-phase ground fault occurs.Therefore,it is of great practical significance to carry out the research on single-phase ground fault location in distribution network.In this thesis,fault location is divided into fault section location and fault distance calculation process,and a distribution network single-phase ground fault location method based on multi-source information is proposed.Firstly,the steady-state and transient characteristics of single-phase ground fault in distribution network are analyzed respectively for the neutral point ungrounded and neutral point grounded through arc suppression coil.Among them,the steady-state characteristics of the neutral grounding system through the arc suppression coil are not obvious,so this paper extracts and analyzes the fault transient signals,and uses the direction relationship of the zero-sequence current in the line as the basis for fault location.The time-frequency analysis tool wavelet transform is selected to analyze the fault signal.By analyzing the zero-sequence voltage,the fault time is determined and the transient fault is distinguished from the permanent fault.By analyzing the zero-sequence current,a fault section location method based on the combination of wavelet mode extremum theory and matrix method is proposed,which solves the influence of arc suppression coil on fault location and has high reliability.Then for fault location based on single end impedance method is easily affected by transition resistance and the question of error range,this thesis adopts the method based on double-end synchronous phasor information to achieve distribution network fault distance,and in line with the actual operation parameters given parameter error problems is proposed based on parameter correction and double-end synchronous phasor information of fault distance calculation method,the method makes full use of the advantage of synchronized phasor measurement device,eliminate the effect of transition resistance as well as the data are not synchronized,effectively improve the precision of fault location.At the end of this thesis,the proposed method is verified by simulation.Firstly,the fault characteristics of distribution network are verified,and the simulation results are consistent with the theoretical analysis.Then the fault location method is simulated and analyzed to verify the feasibility and effectiveness of the proposed fault location method.