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Power distribution network overhead line single-phase grounding fault recognition positioning method and fault indicator

A technology for single-phase ground faults and overhead lines, which is applied to fault locations, instruments, and measuring circuits. It can solve the problem that the accurate fault identification rate is less than 60%, and achieve low cost and simple results.

Inactive Publication Date: 2015-07-08
ELECTRIC POWER RES INST OF GUANGDONG POWER GRID
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Problems solved by technology

Statistics show that the existing fault indicators have good recognition ability for phase-to-phase short-circuit faults, and the correct action rate is greater than 80%, but for single-phase ground faults, especially in small current systems, the fault accurate recognition rate is less than 60%

Method used

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  • Power distribution network overhead line single-phase grounding fault recognition positioning method and fault indicator

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Embodiment Construction

[0015] The working principle of the present invention is as follows:

[0016] When a single-phase ground fault occurs on the line, the system will undergo the following changes:

[0017] (1) Sudden change in voltage

[0018] For the small current grounding system, when a fault occurs, the neutral point of the system shifts, and the non-faulted phase voltage rises to the line voltage, which is about

[0019] For a large-current grounding system, a single-phase ground fault is equivalent to a short circuit occurring near a directly grounded neutral point, the fault phase voltage is approximately equal to 0, the non-fault phase voltage is reversed, and the absolute value of the voltage is approximately

[0020] (2) Sudden change in zero sequence current

[0021] For the small current grounding system, since the neutral point is not effectively grounded, a zero-sequence loop cannot be formed, but each line of the system has a ground-to-ground capacitive current. When the lin...

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Abstract

The invention provides a power distribution network overhead line single-phase grounding fault recognition positioning method and a fault indicator. The power distribution network overhead line single-phase grounding fault recognition positioning method includes the following steps that 1, after a circuit operates normally, the electric field intensity or voltage of the circuit is detected, and if it is detected that the brake variable of the electric field intensity of a certain phase of the circuit or the voltage or the brake variable of the voltage exceeds the set grounding fault threshold value and lasts more than a period of time, a fault early-warning signal is sent out; 2, the current waveforms of the three phases of the circuit are collected synchronously, zero-sequence current synthesis is conducted, and if the circuit zero-sequence current or zero-sequence current brake variable is larger than the set threshold valve, it is judged that the single-phase grounding fault exists in the circuit. By means of the method, the power distribution network overhead line single-phase grounding fault can be recognized and positioned quickly.

Description

technical field [0001] The invention relates to the technical field of fault identification and fault section location of overhead lines of distribution networks. Background technique [0002] my country's medium-voltage distribution lines are dominated by overhead lines, accounting for about 70% of the total line length. Due to the long-term exposure of the overhead line to the wild, it is greatly affected by the surrounding natural environment and human factors, and the line failure rate is relatively high. Statistics show that most of the current user power outages are caused by the distribution network. According to the statistics of a power grid company in 2014, outages caused by the distribution network accounted for more than 95% of the user's power outages in the year, of which fault outages accounted for 63.4% of the total user outages, and distribution network pre-arranged power outages accounted for 32.3%. Therefore, quickly determining the faulty section of the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/02G01R31/08
CPCY04S10/52
Inventor 李传健陈炯聪郑文杰
Owner ELECTRIC POWER RES INST OF GUANGDONG POWER GRID
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