A distribution network fault line selection method based on Min's distance of characteristic frequency band convergence

A technology of distribution network faults and characteristic frequency bands, which is applied in the direction of fault location and fault detection according to conductor type, can solve the problems of extended power outage time, operation overvoltage and resonance overvoltage distribution network impact, etc., and achieve the goal of improving accuracy Effect

Active Publication Date: 2020-09-25
KUNMING UNIV OF SCI & TECH
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  • Summary
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the fault cannot be eliminated after automatic reclosing, the power outage time will be prolonged, and the resulting operating overvoltage and resonance overvoltage will have an impact on the distribution network. Therefore, it is extremely important to accurately and reliably select faulty feeders

Method used

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  • A distribution network fault line selection method based on Min's distance of characteristic frequency band convergence
  • A distribution network fault line selection method based on Min's distance of characteristic frequency band convergence
  • A distribution network fault line selection method based on Min's distance of characteristic frequency band convergence

Examples

Experimental program
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Effect test

Embodiment 1

[0041] Embodiment 1: A method for fault line selection of distribution network based on characteristic frequency band convergence Min's distance, including the following steps: when a single-phase grounding fault occurs in the distribution network, the zero-sequence current data of each feeder is collected. The zero-sequence current in the window uses wavelet transform to calculate the total energy of each feeder in each frequency band, determines the characteristic frequency band according to the energy and maximum principle, calculates the convergent Min's distance of the characteristic frequency band between each feeder, and forms the fault distance matrix of the characteristic frequency band , using the fault distance matrix of the characteristic frequency band to calculate the comprehensive fault distance between each feeder, obtain the relative probability of single-phase grounding fault on each feeder according to the comprehensive fault distance between the feeders, and ...

example 1

[0065] Example 1: as figure 1 The single-phase-to-ground fault simulation model of the 110kV / 35kV distribution network shown has 4 overhead feeders and all of them contain branch lines. The neutral point of the Z-shaped transformer is grounded through the series resistance of the arc suppression coil. Set feeder L 1 A metallic single-phase grounding fault occurred at the branch line 1 2 kilometers away from the main line, the fault angle was 90°, and the sampling rate was 5kHz. The specific steps of the single-phase-to-ground fault line selection method in the distribution network based on the characteristic frequency band convergence Min's distance in this example are as follows:

[0066] After the single-phase grounding fault occurs in the resonant grounding system, wavelet transform is used for the zero-sequence current in the 5ms short-time window after each feeder fault, such as image 3 As shown, scale 5 energy sum maximum, according to the energy sum maximum principl...

example 2

[0074] Example 2: 110kV / 35kV resonance grounding system distribution network single-phase grounding fault simulation model is the same as example 1, feeder L 4 A single-phase grounding fault occurs at the branch line 2 3km away from the main line, the grounding resistance is 200Ω, the fault angle is 60°, and the sampling frequency is 5kHz.

[0075] In the same way as Example 1, such as Figure 5 As shown, the energy sum of scale 6 is the largest, and the characteristic frequency band is determined to be 78.125Hz to 156.25Hz, and the characteristic frequency band of the zero-sequence current is as follows Image 6 As shown, calculate the characteristic frequency band fault distance matrix D, the comprehensive fault distance matrix d and the relative probability matrix P between each feeder;

[0076]

[0077] d=[5.36 5.38 5.41 14.07]

[0078] P=[0.18 0.18 0.18 0.46]

[0079] Select the top three with the highest relative probability of single-phase grounding, and they are ...

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Abstract

The invention relates to a fault line selection method for a distribution network based on a convergence Minkowski distance of a feature band, and belongs to the technical field of power system relayprotection. The method comprises the steps of: collecting the zero-sequence current data of each feeder when a single-phase ground fault occurs in the distribution network; calculating the total energy of each feeder at each scale by using the wavelet transform on the zero-sequence current in a short-time window; determining the feature bands according to the energy and the maximum principle; calculating convergence Minkowski distances of the feature bands between each feeder to form a fault distance matrix of the feature bands; calculating comprehensive fault distances between each feeder line by using the fault distance matrix of the feature bands; obtaining relative probabilities of occurrence of the single-phase ground fault of each feeder according to the comprehensive fault distancesbetween the feeders; and performing fault line selections according to the relative probabilities of the fault occurrence. Theoretical analysis and extensive simulations show that the effect of the fault line selection method is good.

Description

technical field [0001] The invention relates to a distribution network fault line selection method based on characteristic frequency band convergence Min's distance, and belongs to the technical field of power system relay protection. Background technique [0002] When a single-phase grounding fault occurs in the small-current grounding system of the distribution network, the non-faulty phase-to-ground voltage will rise, and the voltage rise will damage the insulation of the distribution network, and then develop into phase-to-phase or multi-point grounding faults, causing system overvoltage. Therefore, it is necessary to accurately and quickly find the faulty line and isolate the faulty line from the system in time. In order to find the faulty line, the traditional methods are as follows: (1) Manually pull the circuit, manually pull the brakes one by one to determine the faulty line, this method will cause an instantaneous power failure of the normal power supply line and r...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08
CPCG01R31/086
Inventor 李一凡徐泽奇
Owner KUNMING UNIV OF SCI & TECH
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