Triangle looped network transient state quantity unit protection method utilizing voltage and current abrupt change quantity wavelet coefficient correlation analysis

A technology of wavelet coefficient and correlation analysis, applied to electrical components, emergency protection circuit devices, fault locations, etc., can solve problems such as difficult protection methods, effective protection, and no longer applicable

Active Publication Date: 2015-03-04
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to ensure the reliability of power supply, the triangular ring network is widely used in power transmission systems. Due to the special structure of the triangular ring network, it is difficult for some traditional protection methods to effectively protect it. The longitudinal protection method is no longer applicable because the initial traveling wave of the fault will propagate to the measurement end through the loop formed by the sound line

Method used

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  • Triangle looped network transient state quantity unit protection method utilizing voltage and current abrupt change quantity wavelet coefficient correlation analysis
  • Triangle looped network transient state quantity unit protection method utilizing voltage and current abrupt change quantity wavelet coefficient correlation analysis
  • Triangle looped network transient state quantity unit protection method utilizing voltage and current abrupt change quantity wavelet coefficient correlation analysis

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Example 1: Establish as figure 1 The circuit model of the triangular ring network shown. In the system, l MN = 100km, l NQ =70km, l QM = 80km, l PM =70km. It is stipulated that the positive direction of the current is that the busbar points to the line. Now assume that a phase A metallic ground fault F occurs on the line MN 40km away from the M terminal 1 , the initial phase angle is 90°, and the sampling frequency is 20kHz. Through the directional element R at the M, N, and Q terminals 1 , R 2 , R 3 , R 4 , R 5 and R 6 Obtain six sets of transient quantities of fault voltage and current respectively, intercept the data of six sets of transient quantities of voltage and current 0.5 ms after the fault, and perform 8-scale wavelet decomposition on them, and choose db4 as the wavelet basis function to obtain The wavelet coefficients of voltage and current mutations are as follows: Figure 2-7 shown. The correlation coefficient and fault section judgment resu...

Embodiment 2

[0044] Embodiment 2: The same triangular ring network line model as Embodiment 1. Assume that a phase A metallic ground fault F occurs on the line NQ at a distance of 30km from the N terminal. 2 , the initial phase angle is 90°, and the sampling frequency is 20kHz. Through the directional element R at the M, N, and Q terminals 1 , R 2 , R 3 , R 4 , R 5 and R 6 Obtain six sets of transient quantities of fault voltage and current respectively, intercept the data of six sets of transient quantities of voltage and current 0.5 ms after the fault, and perform 8-scale wavelet decomposition on them, and choose db4 as the wavelet basis function to obtain The wavelet coefficients of voltage and current mutations are obtained through correlation analysis, and the correlation coefficients and fault section judgment results are shown in Table 2.

[0045] Table 2 Fault F 2 Time direction element R 1 ~R 6 The comprehensive judgment result of

[0046]

[0047] The judgment resul...

Embodiment 3

[0048] Embodiment 3: The same triangular ring network line model as Embodiment 1. Suppose now that a phase A metallic ground fault F occurs on line PM 50km away from terminal M 4 The initial phase angle is 90° and the sampling frequency is 20kHz. Through the directional element R at the M, N, and Q terminals 1 , R 2 , R 3 , R 4 , R 5 and R 6 Obtain six sets of transient quantities of fault voltage and current respectively, intercept the data of six sets of transient quantities of voltage and current at 0.5 ms after the fault, and perform 8-scale wavelet decomposition on them, and select db4 as the wavelet basis function to obtain The wavelet coefficients of voltage and current mutations, the correlation coefficients and fault section judgment results obtained through correlation analysis are shown in Table 3

[0049] Table 3 Fault F 4 Time direction element R 1 ~R 6 The comprehensive judgment result of

[0050]

[0051] The judgment result is consistent with the ...

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Abstract

The invention relates to a triangle looped network transient state quantity unit protection method utilizing voltage and current abrupt change quantity wavelet coefficient correlation analysis and belongs to the power system relay protection technical field. The method comprise the following steps that: transient state quantities of six groups of fault voltage and current are obtained through directional elements of R1, R2, R3, R4, R5 and R6 respectively at an M, N and Q end when a single-phase grounding fault occurs on a triangle looped network; the transient state quantities of the voltage and current 0.5ms after the fault are respectively intercepted, and 8-scale wavelet decomposition is performed on the transient state quantities; wavelet coefficients of the transient state quantities of the voltage and current under the first scale are selected so as to be subjected to correlation analysis, so that six groups of correlation coefficients, namely, ru,i_R1, ru,i_R2, ru,i_R3, ru,i_R4, ru,i_R5, and ru,i_R6, can be obtained; and when -1<=ru,i_R1<=-0.8, and -1<=ru,i_R2<=-0.8, a line MN fails, if -1<=ru,i_R3<=-0.8, and -1<=ru,i_R4<=-0.8, a line NQ fails, if-1<=ru,i_R5<=-0.8, and -1<=ru,i_R6<=-0.8, a line QM fails, and when any one of the above conditions is satisfied, the fault is determined as an intra-cell fault, and when any one of the above conditions is not satisfied, the fault is determined as an extra-cell fault. As indicated by a large number of simulation experiments, the method is greatly applicable to triangle looped network protection.

Description

technical field [0001] The invention relates to a protection method for a triangular ring network transient quantity unit by utilizing the wavelet coefficient correlation analysis of voltage and current mutation quantities, and belongs to the technical field of electric power system relay protection. Background technique [0002] With the continuous expansion of power system scale and the continuous increase of voltage level, people have higher and higher requirements for the protection of power grid lines. After a fault occurs, it is the relentless pursuit of power grid protection to accurately cut off the fault line at a faster speed and protect the safe operation of the system. When a fault occurs in the power system, fault components from power frequency to high frequency will be generated. These high frequency components contain a lot of information, such as the type, location, direction, degree and duration of the fault. The effective extraction and application of the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26G01R31/08
Inventor 束洪春高利
Owner KUNMING UNIV OF SCI & TECH
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