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Single-phase grounding fault discrimination method of small-current grounding system based on energy model

A single-phase ground fault and small current grounding technology, which is applied in the direction of detecting faults and fault locations according to conductor types, can solve the problem that the grounding duration cannot reach a fixed value, and achieve the effect of reducing complexity

Active Publication Date: 2017-11-28
NR ELECTRIC CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this case, the previous grounding criterion based on the definite-time zero-sequence overvoltage principle was judged as instantaneous grounding rejection because the grounding duration did not reach the fixed value.

Method used

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  • Single-phase grounding fault discrimination method of small-current grounding system based on energy model
  • Single-phase grounding fault discrimination method of small-current grounding system based on energy model
  • Single-phase grounding fault discrimination method of small-current grounding system based on energy model

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Embodiment Construction

[0056] An energy model-based single-phase grounding fault discrimination method for a small current grounding system proposed by the invention is applied to a 3kV-66kV small current grounding system. The specific implementation manners will be described below in conjunction with the accompanying drawings.

[0057] The flow chart of the fault identification program is as follows: figure 1 As shown, the specific implementation steps are as follows:

[0058] Step 1: Collect the zero-sequence voltage of the bus in real time, and calculate the amplitude of the zero-sequence voltage. as attached figure 2 As shown, a protection device is used, installed in the PT cabinet of the busbar, and the PT secondary circuit is connected to the protection device. The protection device collects the zero-sequence voltage of the busbar in real time, and calculates the zero-sequence voltage amplitude U; further calculation obtains the zero-sequence voltage Per unit value U pu =U / U b , where U...

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Abstract

The invention discloses a single-phase grounding fault discrimination method of a small-current grounding system based on an energy model. According to the invention, zero-sequence electrical quantity is acquired; according to the zero-sequence electrical quantity, energy accumulated at a single-phase grounding fault point is calculated by use of the energy model; and when the energy reaches a fixed value, acting in tripping or giving out alarms, wherein the more serious a fault is, the faster the energy accumulation speed is and the shorter the corresponding action time is. Thus, problems of arc light overvoltage, burning of a cable and injuries and death of people caused by failure to discriminate the fixed time lag zero-sequence overvoltage criteria after single-phase discontinuous grounding are avoided.

Description

technical field [0001] The invention relates to the field of relay protection of power systems, in particular to a method for judging single-phase grounding faults in small current grounding systems. Background technique [0002] In the 3kV-66kV small current grounding system (also known as the neutral point non-effective grounding system), single-phase grounding is a relatively common fault type. When a single-phase grounding occurs in a low-current grounding system, the fault phase-to-ground voltage decreases, the non-fault phase-to-ground voltage rises, and the line voltage is still symmetrical. In this state, due to the small grounding current, in order to ensure the reliability of power supply, it is allowed to run 1- 2h. However, due to the non-fault phase arc overvoltage, it is easy to cause breakdown of weak insulation parts, voltage transformer iron core saturation, system overvoltage, and the fault phase arc burns the cable, which is easy to cause personal electri...

Claims

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Application Information

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IPC IPC(8): G01R31/08
CPCG01R31/085
Inventor 石勇侯炜陈俊王栎涛李宇琦
Owner NR ELECTRIC CO LTD