Single-phase ground fault locating method based on zero sequence voltage starting

Abstract

The invention relates to a single-phase ground fault locating method based on zero sequence voltage starting. Zero sequence voltage is adopted as a single-phase ground fault break variable starting component, when a ground fault appears, a bus zero sequence voltage starting device can record zero sequence voltage waveforms at the break moment T, three-phase current waveforms of all high-precisiontransient wave recording type fault indicators installed along a transformer substation outgoing line at the same moment are called, and finally fault positioning is achieved based on wide area synchronous information. The purpose of single-phase ground fault locating in an existing power distribution network is achieved.

Description

technical field [0001] The invention belongs to the field of electronic technology, in particular to a single-phase ground fault location method based on zero-sequence voltage startup. Background technique [0002] With the rapid development of the national economy, the scale of the power system is also growing, the network structure is becoming more and more complex, and users have higher and higher requirements for the stability of power supply, all of which require us to continuously strengthen the power system. Upgrade to avoid faults during system operation. Even if a fault occurs, it is necessary to quickly and accurately find the location of the fault after the fault occurs, and then quickly eliminate the fault to ensure the safe operation of the power system and minimize losses. [0003] Most distribution networks in my country generally adopt the low-current grounding method that the neutral point is not grounded or grounded through the arc suppression coil. When a...

AI Technical Summary

Problems solved by technology

The method of manually pulling the circuit will cause the normal line to lose power instantaneously; if the automatic reclosing action is unsuccessful, the power outage time will be prolonged; PT damage; For unattended substations, remote control operation is required, which increases the risk of accidents and the burden on equipment

[0005] With the research and development of single-phase ground fault line selection and location methods in small-current grounding systems, a single-phase ground fault location method based on electric field sudden change has emerged in recent years, and has been applied to ordinary transient state recorders. On the fault indicator, but this method has defects in principle, so the practical effect is not good. The main problems are:

[0006] 1) The starting element is unreasonable

[0007] Ordinary transient recorder fault indicators use electric field mutation as the starting element for ground faults, which are easily disturbed by external factors (environment, climate, arrangement of overhead lines) and cause malfunction or refusal to operate

[0008] 2) The sampling frequency is too low

Without high-quality sampling data, it is easy to lead to misjudgment

[0010] 3) Synchronization accuracy is too low

If the synthetic zero-sequence current error caused by synchronization error is greater than the actual grounding zero-sequence current itself, it will inevitably lead to fault line selection and location errors!

[0012] 4) Most of the local signals are used, and the information is incomplete

If the sampling is not synchronized, and the synchronization time error reaches several milliseconds, the calculated cross-correlation coefficient is very small. At this time, the algorithm fails and the faulty section cannot be determined

The current common type of transient wave recorder has too low synchronization accuracy between fingers, which can only reach 10 milliseconds, and this algorithm cannot be used to realize fault location

[0014] Therefore, although new ground fault location technologies have emerged in an endless stream over the years, the location of single-phase ground faults in low-current grounded systems is still a problem that has not been well resolved.

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