| As a direct connection with users,the operating quality and power supply reliability of distribution systems are closely related to the safety and stability of social life.In addition,in view of the requirements of urbanization and city appearance,the cable deploying rate continues to increase,which results in the consistently increment of capacitive current in the network and it is difficult to be compensated by arc suppression coils.Therefore,the using frequency of lowresistance grounding is increasing.In low-resistance grounding systems,highresistance grounding fault may cause protection malfunctions.As a consequence,high-resistance grounding fault requires rapid and accurate fault location to quickly eliminate the fault.At the same time,it is convenient for maintenance personnel to check and repair the fault in time and avoid serious consequences caused by unable to remove the fault for a long time.Focusing on the high resistance grounding fault in the low-resistance grounding system,the precise identification of high resistance grounding fault in the edge calculation module and the precise fault location method based on the zero sequence voltage distribution characteristics are proposed in this study.Firstly,the transient and steady-state processes of single-phase grounding fault in low-resistance grounding system are analyzed.The variation trend of transient current is explained,and the composition of zero sequence current and the distribution law of zero sequence voltage along the line are qualitatively analyzed.It lays a foundation for the establishment of fault section and accurate location method in the following paper.Secondly,the general distribution characteristics of zero-sequence current amplitude in low-resistance grounding and the distribution characteristics of zerosequence current amplitude in hybrid feeders(cables and overhead lines)are qualitatively analyzes.Based on this,the fault zone location criterion is determined.In addition,in order to reduce the pressure of communication and improve the utilization of information,edge computing is used in the positioning algorithm processing and the arrangement of edge nodes is introduced.Carried on the simulation analysis in the IEEE 34 node system,the effectiveness of the fault section location is verified.Finally,in order to solve the problem of precise fault location,a line parameter model combining the distribution model with concentration model and considering line impedance is proposed at the beginning.By this model,the distribution characteristics of zero-sequence voltage are quantitatively analyzed.Furthermore,to solve the problem of non-synchronization error in the voltage and current measurement devices at the head and end of the distribution network,a phase correction method for non-uniformly distributed measurement is proposed,and the corrected zero-sequence voltage and current at the head and end of the line are used to accurately locate the fault.At the same time,the insulation state of cable line is estimated by using the zero-sequence current information after the grounding fault.Finally,the effectiveness and reliability of the algorithm are simulated and verified in IEEE 30 nodes system,and the results show that the proposed algorithm has high fault location accuracy and high reliability.The paper contains 49 figures,20 tables and 84 references. |
