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Single-phase-to-earth fault location method for distribution network cables using transient main frequency components

A technology of fault distance measurement and phase-to-grounding, which is applied in the fault location and other directions, and can solve the problems of weak steady-state residual current and difficult signal extraction

Active Publication Date: 2016-08-17
STATE GRID CORP OF CHINA +2
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Problems solved by technology

The double-ended method is mainly based on the principle of equal voltage from the two ends of the line to the fault point to construct the ranging equation. The principle is simple and reliable, but it is restricted by double-ended asynchronous sampling and system communication equipment.
In addition, the steady-state residual current after the fault is weak, and the signal is not easy to extract

Method used

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  • Single-phase-to-earth fault location method for distribution network cables using transient main frequency components
  • Single-phase-to-earth fault location method for distribution network cables using transient main frequency components
  • Single-phase-to-earth fault location method for distribution network cables using transient main frequency components

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Embodiment Construction

[0054] The present invention will be further described below in conjunction with accompanying drawing:

[0055] The present invention comprises the following steps:

[0056] Step (1), sampling the three-phase transient current signal i of the first end (M end) of the faulty cable line MA (t), i MB (t), i MC (t) and three-phase transient voltage signal u MA (t), u MB (t), u MC (t). The sampling frequency of the data is 10kHz, and the time window is the half cycle (10ms) after the fault;

[0057] Step (2), obtain the 0-mode component u of the voltage at the head end of the faulty cable line M0 (t) and the 0-mode component i of the current M0 (t):

[0058] ①. In step (1), the first-end three-phase transient voltage signal sequence value u of the faulty cable line obtained by sampling MA (t), u MB (t), u MC (t) Perform Karenbuaer phase-mode transformation to obtain the 0-mode component u of the voltage at the head end of the faulty cable line M0 (t), the specific tran...

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Abstract

A conventional line hyperbolic function model is usually used for calculation of phase quantity of power frequency steady state quantity. The model is improved by utilizing Laplace transformation. With combination of a zero mode network after a distribution network cable single-phase ground fault, a single-end distance measuring algorithm utilizing the transient main frequency component is provided, and solving is performed via a frequency domain mode and a time domain mode respectively so that fault distance is obtained. Influence of transition resistance is eliminated by the frequency domain mode, and result optimization is performed by the time domain mode by utilizing redundancy of sampling points. Correctness of the method is verified by a large amount of EMTP simulation experiment results without influence of factors, such as transition resistance, neutral point operation modes, fault initial angles, etc., the maximum relative error of distance measurement is less than 0.231%, an average distance measurement error is less than 20m, and thus practical engineering requirements can be met.

Description

technical field [0001] The invention relates to a single-phase grounding fault ranging technology of a distribution network cable, and specifically designs a single-phase grounding fault distance measuring method of a distribution network cable using a transient main frequency component. Background technique [0002] With the rapid development of the national economy and the transformation of urban power grids, various types of power cables have been widely used in high and low voltage power transmission and distribution, and the number is increasing. Almost all 10kV power distribution lines in many cities Power cables are used for power supply, and the 110kV urban ring network in some large cities has also begun to be "underground" transformation. Compared with overhead lines, power cables have high power supply reliability, are not affected by ground objects and spaces, are not affected by bad weather and birds, are concealed, safe, durable, moisture-proof, anti-corrosion ...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08
Inventor 唐昆明黄翰冯彦唐辰旭胡建杨伟康丽红陈洪波孙小江
Owner STATE GRID CORP OF CHINA
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