Single-phase grounding fault locating method for distribution network without master station

Abstract

A single-phase grounding fault locating method for a distribution network without a master station of the invention comprises the following steps: (1) each distribution terminal detects the zero sequence voltage value of a distribution network, and judges whether there is a single-phase grounding fault; (2) when there is a single-phase grounding fault, each distribution terminal takes the derivative of zero sequence voltage, compares the polarity of transient zero sequence current with the polarity of the derivative of zero sequence voltage, and identifies a single-phase grounding fault line; (3) a line meeting the condition that the polarity of transient zero sequence current and the polarity of the derivative of zero sequence voltage are opposite is selected as a fault line, and each distribution terminal sends a grounding fault locking signal containing level information to a higher-level line distribution terminal; (4) the distribution terminal at the fault point does not receive a grounding fault locking signal, and acts first to remove the grounding fault, and the distribution terminals upstream of the fault do not malfunction; and (5) if the distribution terminal at the fault point fails to remove the fault in time, the higher-level feeder distribution terminal delays the action exit gradually according to the received locking signal. Through the method, a grounding fault point can be located accurately even when a distribution terminal on a switch loses communication connection with a distribution monitoring master station system.

Description

technical field [0001] The invention relates to the field of distribution automation of electric power systems, and relates to a method for selecting lines with one-way grounding faults. Background technique [0002] In the domestic power distribution network system, whether it is a neutral point ungrounded system, or a neutral point grounded system through a small resistance, or a grounded system through an arc suppression coil, when a single-phase grounding occurs in the power distribution network, there will be a fault on the fault line. The ground leakage current will be generated, and the ground capacitive current will be generated on the healthy feeder, and the size of the capacitive current to the ground is related to the length of the cable. The longer the cable, the greater the capacitive current, which leads to the zero sequence current setting of the ground protection. difficulty. [0003] At present, the conventional ground fault detection generally adopts the e...

AI Technical Summary

Problems solved by technology

[0007] Due to the different lengths of the distribution lines in the distribution network and the unreasonable setting of the zero-sequence current setting of the upper and lower level distribution switches, when a one-way ground fault occurs, it often leads to the failure of the upper level switch, the lower level switch and the nearby non-faulty lines on the fault line. The switches on the line operate at the same time; and a single power distribution terminal cannot accurately select the line and locate the ground fault point, or rely on the master station system to collect all terminal fault detection information, and finally locate the ground fault point

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