Dynamic resistance grounding mode of neutral point of power distribution network, and ground fault line selection method

Abstract

The invention provides a dynamic grounding mode of a neutral point of a power distribution network in a medium-resistance and low-resistance way, and a ground fault line selection method, for the problem existing in a low-resistance grounding mode of the neutral point of the power distribution network at present. The grounding resistance value of the neutral point of the power distribution network can be dynamically converted according to requirements, namely, when the power distribution network is in a normal operating state, the neutral point is grounded through a resistor and a serially-connected medium resistor for limiting each kind of overvoltage in the power distribution network; when a displacement voltage of the neutral point rises to a fault starting voltage, it is determined that the power distribution network suffers from single-phase grounding immediately; firstly, a grounding fault region is determined according to the displacement voltage value of the neutral point, and at the moment, the low-resistance grounding mode is performed; the neutral point is grounded through the serially-connected medium resistor, a single-phase grounding fault line is selected out by a zero sequence current amplitude-comparing method, and at the moment, a high-resistance grounding mode is performed; and the grounding of the neutral point is converted to low-resistance grounding, and a fault loop current is accelerated to satisfy the detection sensitivity of a zero sequence current transformer so as to select out and cut away the fault line.

Description

technical field [0001] The invention mainly relates to the field of neutral point grounding of a distribution network, in particular to a dynamic resistance grounding mode and a grounding line selection method for a neutral point of a distribution network, and is suitable for single-phase grounding fault processing of a 6-66kv distribution network. Background technique [0002] Different neutral point grounding methods of distribution network have great influence on power supply reliability, internal overvoltage level and lightning arc establishment rate. The neutral point grounding method of the distribution network involves many factors such as the structure of the distribution network, the insulation level of lines and equipment, the configuration of relay protection, the communication system, and personal safety. The neutral point grounding methods of distribution network are: (1) neutral point is insulated from ground; (2) neutral point is grounded through arc suppressi...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problems existing in the current distribution network neutral point small resistance grounding method, the present invention invents a distribution network neutral point dynamic resistance grounding method and a grounding line selection method. Combined with the conversion of the low resistance mode and the grounding line selection method, the accuracy of the line selection of the distribution network is solved, especially the line selection problem of the broken line of the distribution network passing through the transition resistance grounding

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