Research On Multi Criteria Fusion Line Selection Technology Of Zero Sequence Current Component Improvement

With the rapid development of power system,the scale of power grid is becoming larger and larger,along with the increase of power users’ demand for power supply reliability.Small current grounding system is an important part of the distribution network.When single-phase grounding fault occurs,the line selection and location technology is one of the main problems that perplex the relay protection of medium and low voltage distribution network.Aiming at the problems of low sensitivity and poor reliability of existing fault line selection methods for single-phase to ground fault in ungrounded neutral system,an improved multi criteria fusion fault line selection and location method based on zero sequence current component is proposed.The fault line selection and location system is based on the principle of differential line selection,combined with multiple transient and steady-state line selection methods for information fusion,complementary advantages,comprehensively improve the accuracy of fault line selection,and can make up for the defects of existing methods.This paper analyzes and summarizes the existing line selection methods and zero sequence current characteristics when single-phase to ground fault occurs in small current grounding system,and verifies the feasibility of the differential line selection method through MATLAB simulation and physical experiment,but it also finds that the differential line selection method is still insufficient,and analyzes and compares the complementary criteria for its problems,The Delphi method is used to evaluate the multi criteria route selection method,and the corresponding membership function is determined.Fuzzy comprehensive evaluation method is used to optimize the system fitness of each line selection method by membership function,so as to further improve the accuracy of fault line selection and location method based on improved multi criteria fusion of zero sequence current component.Finally,through a large number of simulation experiments by MATLAB simulation,it is found that the proposed method has higher sensitivity and accuracy than the previous methods,and can accurately complete the problem of line selection and location when single-phase grounding fault occurs in small current grounding system,which is of great significance to improve the reliability of power supply system.