Single-phase ungrounded fault locating method for isolated neutral system based on zero-sequence current

Abstract

The invention proposes a single-phase ungrounded fault locating method for an isolated neutral system based on a zero-sequence current. Each line is set as a node at an outgoing line switch side of atransformer substation and a line segmentation point when a single-phase ungrounded fault happens to a grid system in a neutral ungrounded state. The method comprises the following steps: 1, collecting a zero-sequence current of each node; 2, sorting the magnitudes of the zero-sequence currents collected from all nodes; 3, determining that the line where the maximum zero-sequence current is located is a fault line; 4, determining that a line segment between the node where the maximum zero-sequence current is located and its neighboring node is the fault segment. According to the scheme of theinvention, the method can quickly and accurately locate the fault segment of the line of the ground loss when the single-phase ungrounded fault happens to the isolated neutral system of a power distribution network under the conditions that the smaller and lower-cost reconstruction of a current network, and reduces insulating repeated impact on the system from the blind pulling of a switch. The method is low in cost, simple in implementation, high in efficiency, high in accuracy, and safe and reliable.

Description

technical field [0001] The invention belongs to the field of grid fault detection, and in particular relates to a single-phase ground loss fault location method for a neutral point ungrounded system based on zero-sequence current. Background technique [0002] At present, for the distribution network neutral point ungrounded system, when a single-phase fault occurs in the line, the low-current grounding line selection technology in the substation or the trial switch is mostly used to judge the lost section of the line fault. In the process of actual power grid maintenance and fault handling, the accuracy of using the small current grounding line selection technology to judge the ground loss fault section is generally low, so the popularization and application of this technology is greatly limited. However, the method of trying to pull the switch based on the experience of the operating personnel is often very blind. It needs to be tried many times and at the same time observ...

AI Technical Summary

Problems solved by technology

In the process of actual power grid maintenance and fault handling, the accuracy of using the low-current grounding line selection technology to judge the ground-lost fault section is generally low, so the popularization and application of this technology is greatly limited

However, the method of trying to pull the switch based on the experience of the operating personnel is often very blind. It needs to be tried many times and at the same time observe whether the bus voltage has a ground loss signal to judge, which takes a long time and affects the reliability of the power supply; at the same time, repeatedly try to pull the switch , the system will repeatedly lose ground, which will also cause multiple shocks to the system insulation

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