Determining method for power distribution network single-phase earth fault contingency set

Abstract

The invention relates to a determining method for a power distribution single-phase earth fault contingency set. The method includes the following steps that step1, a power distribution network equivalent circuit diagram is established; step2, the starting end voltage of a feeder line section and the current which flows through the section are calculated; step3, an impedance method is used for performing a fault diagnosis on the feeder line section, measurement impedance at the fault moment is obtained through calculation by the utilization of voltages and currents before and after a fault at the starting end of the feeder line section and then compared with unit impedance of the feeder line section to obtain a possible fault distance, and therefore all feeder line sections within the fault distance are possible fault sections; step4, the step2 and the step3 are repeated, a fault diagnosis is performed on other feeder line sections until all the feeder line sections are judged, and the set of all the possible fault sections is the contingency set of the fault. According to the method, the fault diagnosis is independently performed on each feeder line section, so that errors, which are generated because many branch circuits and single-phase lines of a power distribution network are arranged, of the impedance method are eliminated, and the accuracy of the fault diagnosis of the power distribution network is improved.

Description

technical field [0001] The invention relates to the technical field of distribution network fault diagnosis, in particular to a method for determining an expected accident set of a single-phase grounding fault of a distribution network. Background technique [0002] The distribution network is much larger than the transmission network in terms of its scale, and the probability and number of failures are also far greater than the probability and number of failures in the transmission network. According to statistics, 80% of the faults in the power system come from the distribution network. ; In addition, the distribution network is a network that directly supplies power to users, and its failure will directly affect the power quality of users. Therefore, how to accurately diagnose the possible fault points or faulty feeder segments after the failure of the distribution network, Taking isolation measures in time is an important issue to ensure the safe and stable operation of ...

AI Technical Summary

Problems solved by technology

First of all, there are few branch lines in the transmission network between two substations, while there are a large number of branch and sub-branch feeders in the distribution network, so that when a fault occurs, the fault voltage and current measured at the beginning of the feeder may correspond to different feeder segments, and these different feeder segments may generate the same fault voltage and current; secondly, the transmission network usually operates in three-phase symmetry, but since most users in the distribution network are single-phase, the distribution network in a There may be asymmetrical operation in an area, and there are a large number of single-phase lines; again, the influence of load does not need to be considered too much in the fault diagnosis of the transmission network, but in the distribution network, due to the close relationship with the load, the load is in a state of real-time change , and the load in the distribution network is distributed along the line, so the impact of the load on fault diagnosis needs to be considered; in addition, there are some other factors, such as short distribution network lines, etc., which lead to The fault diagnosis of the transmission network is different from that of the distribution network. Therefore, the fault diagnosis methods used in the past for the transmission network cannot be fully applied to the distribution network, and it is necessary to redesign the fault diagnosis method suitable for the distribution network.

[0004] At present, there are traveling wave fault diagnosis methods and intelligent algorithm-based fault diagnosis methods for distribution network fault diagnosis. However, most of these methods are introduced from the transmission network to the distribution network. , so that these methods have certain disadvantages in the application of distribution network, and need to be improved according to the characteristics of distribution network

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