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Method and system for detecting cable single-phase earth fault

A single-phase ground fault and detection method technology, which is applied in the field of power transmission and distribution, can solve the problems of low detection accuracy, incompleteness, and delay in production, and achieve the effect of high detection accuracy and avoiding power outages

Active Publication Date: 2017-12-05
STATE GRID SICHUAN ELECTRIC POWER CORP ELECTRIC POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is that current cable fault detection methods mostly use offline detection methods. Off-line detection requires power failure for detection, which delays production. At the same time, the state of the equipment during power failure is not exactly the same as that when it is turned on, and the detection accuracy is low. The purpose is to provide a cable single-phase ground fault detection method and system to solve the above problems

Method used

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  • Method and system for detecting cable single-phase earth fault
  • Method and system for detecting cable single-phase earth fault
  • Method and system for detecting cable single-phase earth fault

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Embodiment 1

[0032] The cable single-phase grounding fault detection method of the present invention includes the following steps: S1: detecting the current disturbance in the cable; S2: when detecting the current disturbance in the cable, recording the time when the current disturbance occurs; S3: recording the current disturbance in the cable Perform Fourier transform analysis on the data of two weeks before the occurrence time to obtain the initial phase angle of the current disturbance, and judge whether the disturbance occurs at the peak voltage according to the initial phase angle; S4: If the disturbance occurs at the peak voltage, the cable Judgment is made based on the current disturbance, and it is judged whether the current disturbance is a ground fault or a normal equipment disturbance.

[0033] When this embodiment is implemented, the current disturbance in the cable is detected first, and the moment when the current disturbance occurs is recorded. Because the current disturbanc...

Embodiment 2

[0035] On the basis of Embodiment 1, this embodiment also includes the following steps: S5: Comparing the load before the current disturbance with the load after the current disturbance, if the load before the current disturbance is greater than the load after the current disturbance, then determine the current current Perturbations are not cleared.

[0036] When this embodiment is implemented, since the single-phase ground fault sometimes has self-recovery properties, that is, it appears as a transient current disturbance, it is very necessary to determine whether the current single-phase ground fault has been self-recovery. When the present invention is applied, when the load before the current disturbance is greater than the load after the current disturbance, it means that some loads have tripped or fused when a single-phase ground fault occurs, and then it is determined that the single-phase ground fault has not been recovered, which is convenient for the staff to clear th...

Embodiment 3

[0038] In this embodiment, on the basis of Embodiment 1, step S4 also includes the following sub-steps: S41: Simplify the ground fault to ground fault in series with resistance and variable resistance; simplify normal equipment disturbance to ground in series with inductor and resistance; S42: Detect cable The current on the line I 0 (t) and voltage U 0 (t); S43: According to the current I on the cable line 0 (t) and the simplified ground fault to get the ground fault voltage U 1 (t); according to the current I on the cable line 0 (t) and the simplified normal equipment disturbance to get the normal disturbance voltage U 2 (t); S44: According to U 0 (t) and U 1 (t) to get the ground fault error h 1 ;according to U 0 (t) and U 2 (t) get the normal error h 2 ;S45: compare h 1 and h 2 , if h 1 2 , then it is determined that the current disturbance is a ground fault; if h 1 ≥ h 2 , then it is judged that the current disturbance is a normal equipment disturbance.

[...

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Abstract

The invention discloses a method for detecting cable single-phase earth fault. The method includes the steps of S1, detecting current disturbance of cables; S2, recording time of occurrence of current disturbance when the current disturbance of the cables is detected; S3, subjecting data of previous two cycles before the time of occurrence of the current disturbance of the cables to Fourier transform analysis to obtain initial phase angle of the current disturbance, and judging whether the disturbance occurs at the voltage peak or not according to the initial phase angle; S4, if the disturbance occurs at the voltage peak, then judging whether the current disturbance of the cables is caused by earth fault or is normal equipment disturbance. The invention further discloses a system for detecting cable single-phase earth fault by the method. By the method and the system, online detection of disturbance caused by single-phase earth fault is realized, shutdown due to off-line detection is avoided, and production delay is omitted; further, since the cables are subjected to online detection and equipment on line is in normal service state, the detection accuracy is high.

Description

technical field [0001] The invention relates to the technical field of power transmission and distribution, in particular to a cable single-phase ground fault detection method and system. Background technique [0002] With the rapid development of the national economy and the transformation of urban power grids, a large number of distribution lines are powered by power cables. The advantages of cables are obvious, such as safety, reliability, and good concealment. However, due to the manufacturing process, maintenance process, insulation aging, external force damage and other reasons, the cable itself has different types of faults during operation. Accurate and rapid analysis, search and treatment of faults are reliable guarantees for timely power transmission and operation of electrical equipment. support. [0003] At present, the offline detection method is mostly used for cable fault detection. Because offline detection requires power failure for detection, production is...

Claims

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Application Information

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IPC IPC(8): G01R31/02G01R31/08
CPCG01R31/083G01R31/50
Inventor 陈缨何婧宇范松海刘小江肖先勇陈坤燚
Owner STATE GRID SICHUAN ELECTRIC POWER CORP ELECTRIC POWER RES INST
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