A Differential Processing and Fault Area Isolation Method for Single-phase-to-ground Fault in Distribution Network

Abstract

A method for differentiated treatment of single-phase ground faults and fault area isolation in a distribution network. The complete set of devices consists of a dynamic intelligent resistance grounding device, a feeder zero-sequence protection, a feeder node zero-sequence current sensor, a feeder node intelligent switch, and a control system. When a single-phase ground fault occurs in the power grid, the fault is processed through different delays. In the event of a high-resistance fault, the ground fault line is selected, and the fault current path is checked to judge and isolate the fault area. In the case of low-resistance faults, it cooperates with feeder zero-sequence protection and node intelligent switches to achieve differentiated fault handling and fault area isolation to reduce the scope of power outages.

Description

technical field [0001] The invention mainly relates to the field of single-phase grounding fault processing of distribution network, and particularly refers to a method for differentiated processing and fault area isolation of single-phase grounding fault of distribution network, which is suitable for single-phase grounding fault processing of 6-66kv distribution network. Background technique [0002] The distribution network neutral point small resistance grounding method is used in the distribution network with zero-sequence protection. During normal operation, the overvoltage level is low. When a single-phase ground fault occurs, the faulty line is cut off through zero-sequence protection. The grounding method has a simple structure and has been widely used in urban power grids. However, the biggest defect of this grounding method is that once a high-impedance grounding such as single-phase disconnection or personal electric shock occurs in the distribution network, the ze...

AI Technical Summary

Problems solved by technology

[0002] The distribution network neutral point small resistance grounding method is used in the distribution network with zero-sequence protection. During normal operation, the overvoltage level is low. When a single-phase ground fault occurs, the faulty line is cut off through zero-sequence protection. The grounding method has a simple structure and has been widely used in urban power grids. However, the biggest defect of this grounding method is that once a high-impedance grounding such as single-phase disconnection or personal electric shock occurs in the distribution network, the zero-sequence protection will "fail" and cannot be selected in time. And cut off the fault line, so that the fault point poses a greater threat to personal safety. There have been many such accidents in China

When the high-resistance grounding of the cable line occurs, due to the "failure" of the zero-sequence protection, the faulty line cannot be cut off in time, and the long-term arc will cause multiple cables to burn out

If the small resistance grounding method is used in the overhead power grid, the reliability of the power supply will be greatly reduced due to the tripping of the overhead line when it is grounded instantaneously.

[0003] Some distribution lines are long, with many users, and some have many branch lines. If a permanent single-phase ground fault occurs, if the entire line is cut off, it will cause a large-scale power outage, which will greatly improve the reliability of power supply for users. Therefore, it is possible to find an intelligent dynamic resistance grounding device, combined with zero-sequence protection and distribution network intelligent switch, which can reduce the internal overvoltage level when the distribution network is in normal operation, and single In case of phase disconnection, grounding fault, or personal electric shock fault, the fault can be accurately selected and quickly removed, and the fault area can be isolated to ensure equipment and personal safety