Research On Line Selection Method Of Single-Phase Grounding Fault In Distribution Network

With the continuous complexity of the distribution network structure,the probability of single-phase grounding faults is increasing,which seriously affects the operation safety of the distribution network.It is very important to find the fault location and find the faulty line in time.The method of fault line selection using the single line selection principle is difficult to meet the operation requirements of the power system in practical applications,and the accuracy and reliability are relatively poor.Therefore,the use of multi-source criteria for comprehensive line selection has gradually become the current development trend.When the small current grounding system fails,the fault current component in the line is not large,and the distribution network system can continue to operate symmetrically with the fault,and the continuous power supply will not be affected.Operation with faults endangers the safety of the power grid,and the problem of line selection is urgently needed.Due to the difficulty of line selection,the accuracy of single-phase ground fault line selection still has not been more practically improved.This paper further researches on the difficult problem of route selection,and uses multi-source criterion fusion to realize route selection.There are two common grounding methods for the neutral point in the distribution network in my country.This article first uses the equivalent circuit model to theoretically analyze the two main characteristics of the neutral point ungrounded and the neutral point grounded through the arc suppression coil.That is,steady-state characteristic quantities and transient characteristic quantities,a mathematical model of differential equations is established,and the mathematical expressions of fault zero-sequence voltage and zero-sequence current are obtained,and the results of the theoretical analysis are verified by the comparison and analysis of the formula derivation results.After comprehensively analyzing the changes of the steady-state component and the transient component,select the line selection principle,such as the zero-sequence current ratio-amplitude ratio-phase method,energy method,zero-sequence current fifth harmonic method,and zero-sequence reactive power method.Each line selection principle has its own scope of application and limitations.Due to the lack of accuracy of the single route selection method,it is proposed to use information fusion technology to judge the route selection.The MATLAB simulation software is used to build the model.The simulation model uses six basic line selection principles to form the basis of the multi-source criterion.The use of information fusion technology,based on the algorithm basis of fuzzy theory,establishes a fault membership function for each line and determines the criterion weight coefficient function for each method.After the fault membership function and the calculated value of the criterion weight coefficient function are used,the line selection result is obtained after fusion decision-making.Finally,through a large amount of data simulation and experimental waveform analysis,the correctness and reliability of the line selection method based on the multi-source criterion fusion technology has been verified.The line selection method proposed in this paper has achieved correct line selection in order to solve the problem of line selection.Provide method help.