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Method for detecting internal and external faults of ultra high voltage direct current transmission lines based on pole wave mathematical morphology spectrum

A UHV DC, mathematical form technology, applied in the direction of measuring electricity, measuring devices, measuring electrical variables, etc., can solve the problems of transition resistance noise interference fault distance, protection malfunction or refusal, protection influence, etc., to achieve a simple calculation method. , the conclusion is accurate, the result is accurate

Active Publication Date: 2015-05-20
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Its protection is based on the current gradient, voltage traveling wave conversion rate and voltage traveling wave mutation as the criterion, but its protection is easily affected by transition resistance, especially when there is an external fault, the fault traveling wave passes through the flat wave at the end of the DC line. For reactors and DC filters, the voltage conversion rate is reduced, which is likely to cause malfunction or refusal of protection, which has a great impact on the stable operation of the DC system
Therefore, the main protection of the DC system based on the change rate criterion is easily affected by transition resistance, noise interference, fault distance, etc.

Method used

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  • Method for detecting internal and external faults of ultra high voltage direct current transmission lines based on pole wave mathematical morphology spectrum
  • Method for detecting internal and external faults of ultra high voltage direct current transmission lines based on pole wave mathematical morphology spectrum
  • Method for detecting internal and external faults of ultra high voltage direct current transmission lines based on pole wave mathematical morphology spectrum

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Example 1: ±800kV DC transmission line (transmission system structure such as figure 1 shown). The power transmission capacity of the transmission line is 5000MW, the reactive power compensation capacity of the rectification side and the inverter side is 3000Mvar and 3040Mvar, each pole commutation unit is composed of two 12-pulse converters, and a 400mH smoothing reactor is installed on the DC line side , the DC filter is a 12 / 24 / 36 three-tuned filter; the line is a six-split conductor, using the J.Marti frequency line model, and the total length of the line is 1500km; the physical boundary of the DC is as follows figure 2 As shown, among them, L =400mH, L 1 =39.09mH, L 2 =26.06mH, L 3 =19.545mH, L 4 =34.75mH, C 1 =0.9μF, C 2 =0.9μF, C 3 =1.8μF, C 4 =0.675μF.

[0034] The positive ground fault of the DC transmission line is 200km away from the protection side, and the transition resistance is 10Ω.

[0035] The specific steps for monitoring and iden...

Embodiment 2

[0041] Embodiment 2: The structure and parameters of the power transmission system are the same as in Example 1, and the steps of monitoring and identifying faults are the same as in Example 1.

[0042] The rectifier side of the DC transmission line outside the area has a positive ground fault, and the transition resistance is 5 ohms. The sampling short data window length is 5ms, and the sampling frequency is 100kHz; when the polar wave voltage is subjected to 4-layer wavelet transformation, the spectrum of the high-frequency transient quantity of the polar wave voltage obtained by extracting the high-frequency part of each layer and adding them is above 3125Hz ;Calculate the high-frequency characteristic quantity of positive line wave voltage PG + ( k ), the positive semi-axis mathematical form spectrum value, the scale r is selected as 9.

[0043] The integral value sought SPS = 3.0316<50, it is judged as an out-of-area fault.

Embodiment 3

[0044] Embodiment 3: The structure and parameters of the power transmission system are the same as in Example 1, and the steps of monitoring and identifying faults are the same as in Example 1.

[0045] The phase A ground fault of the AC bus on the inverter side of the DC transmission line is faulty, and the transition resistance is 5 ohms. The sampling short data window length is 5ms, and the sampling frequency is 100kHz; when the polar wave voltage is subjected to 4-layer wavelet transformation, the spectrum of the high-frequency transient quantity of the polar wave voltage obtained by extracting the high-frequency part of each layer and adding them is above 3125Hz ;Calculate the high-frequency characteristic quantity of positive line wave voltage PG + ( k ), the positive semi-axis mathematical form spectrum value, the scale r is selected as 9.

[0046] The calculated integral value SPS =0.3246<50, it is judged as an out-of-area fault.

[0047] The present invention pe...

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Abstract

The invention provides a method for detecting internal and external faults of ultra high voltage direct current transmission lines based on pole wave mathematical pattern spectrum. The method is characterized in that when a direct current (DC) line fault occurs, a starting component is started, according to positive pole line DC voltage U+(k) and DC I+(k) which are collected by a protection installation location, pole wave voltage of a positive pole line is obtained, and the positive pole line pole wave voltage is subjected to wavelet transform, pole wave voltage high frequency characteristic quantity PG+(k) of a high frequency portion of the positive pole line pole wave voltage is extracted. The pole wave voltage high frequency characteristic quantity is calculated by means of mathematical morphology, a mathematical morphology spectrum value of the pole wave voltage high frequency characteristic quantity is obtained, structure element scale needed is selected, and the mathematical morphology spectrum value is subjected to integration operation along abscissa axis structure element scale. Internal and external faults are distinguished according to the integration operation value. The method has the advantages of being sensitive in identifying the internal faults, reliable in identifying the external faults and applicable to the popularization and the usage in direct current transmission line systems.

Description

technical field [0001] The invention relates to a form spectrum detection method for identifying internal and external faults of UHV DC transmission lines based on polar wave transient quantities, and belongs to the technical field of power system relay protection. Background technique [0002] At present, traveling wave protection is widely used in the world as the main protection of HVDC transmission line protection. It uses the current and voltage traveling waves transmitted at the moment of fault to form ultra-high-speed line protection. Moreover, DC line protection provided by ABB and SIEMENS is adopted in most projects. Its protection is based on the current gradient, voltage traveling wave conversion rate and voltage traveling wave mutation as the criterion, but its protection is easily affected by transition resistance, especially when there is an external fault, the fault traveling wave passes through the flat wave at the end of the DC line. For reactors and DC fil...

Claims

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Application Information

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IPC IPC(8): G01R31/02
Inventor 束洪春万雄彪田鑫萃
Owner KUNMING UNIV OF SCI & TECH
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