Power distribution network single-phase earth fault differentiation processing and fault area isolation method

Abstract

The invention relates to a power distribution network single-phase earth fault differentiation processing and fault area isolation method, which is characterized in that complete equipment consists ofa dynamic intelligent resistance grounding device, a feeder zero-sequence protection device, a feeder node zero-sequence current sensor, a feeder node intelligent switch and a control system, and processes faults by different delays in event of single-phase earth fault in a power distribution network. According to the invention, when a high-resistance fault occurs, a grounding fault line is selected, and a fault current path is checked for fault area judgment and isolation; and when a low-resistance fault occurs, differentiated fault processing and fault area isolation are realized through cooperation with feeder zero-sequence protection and a node intelligent switch so as to reduce a power failure range.

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 affect 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 level of internal overvoltage during normal operation of the distribution network In case of single-phase disconnection grounding fault or personal electric shock fault, it can accurately select and quickly remove the fault and realize the area isolation of the fault to ensure the safety of equipment and personal