Extra-high-voltage direct-current transmission line fault location method based on wavelet transformation transient state energy spectrum

Abstract

The invention relates to an extra-high-voltage direct-current transmission line fault location method based on a wavelet transformation transient state energy spectrum, and belongs to the technical field of power system relay protection. When a direct-current line breaks down, according to two-pole direct-current voltage collected at a protection installation position (img file='dest_path_dest_path_image001. TIF'wi= '40' he='24' / ) and (img file='dest_path_dest_path_image002. TIF'wi= '40' he='24' / ), line mode voltage (img file='dest_path_dest_path_image003. TIF'wi= '48' he='24' / ) is obtained, wavelet decomposition is carried out on line mode voltage (img file='dest_path_855728dest_path_image003. TIF'wi= '48' he='24' / ) to obtain a high-frequency coefficient of the wavlet decomposition, the high-frequency signal wavelet energy sum (img file='dest_path_dest_path_image004. TIF'wi= '21' he='25' / ) is solved by means of the high-frequency coefficient, normalization processing is carried out on (img file='dest_path_594008dest_path_image004. TIF'wi= '21' he='24' / ) to obtain an input sample of a neural network, and the input sample in the neural network is trained to obtain a fault location result. By means of characteristics of a wavelet energy frequency band whose appearance is obvious and whose position is easy to determine, a fault position is looked for, and precision of fault location is improved; by means of non-linear fitting capacity of the neural network, extra-high-voltage direct-current grounded transmission line fault locating is carried out, the property of the sample is clear, the scale of a sample set is small, convergence efficiency is high, and the method is not prone to being influenced by system parameter conversion and transition resistance.

Description

technical field [0001] The invention relates to a fault location method of an ultra-high voltage direct current transmission line based on wavelet transform transient energy spectrum, and belongs to the technical field of electric power system relay protection. Background technique [0002] At present, there is no research on intelligent fault diagnosis of UHV DC transmission system in China, and there are very few intelligent fault diagnosis systems for UHV DC transmission system abroad, and there is still a certain distance from practicality. Most of the existing DC line distance measurement systems use the traveling wave method using the traveling wave propagation characteristics of the transmission line, that is, the fault distance is calculated by measuring the traveling time of the traveling wave on the transmission line. The traveling wave method can be divided into single-ended method and double-ended method. end method. Although the traveling wave ranging method h...

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Problems solved by technology

[0003] (1) The single-ended method requires less investment, but subsequent reflected waves are easily affected by interference signals and difficult to identify; the double-ended ranging method requires installation at both ends of the line Distance measuring device, and requires time synchronization (GPS clock) and communication channel, complex device and large investment

[0004] (2) The traveling wave signal generated by the fault has a large random component, is susceptible to interference, is fleeting, non-repeatable, and difficult to accurately measure and capture

[0005] (3) The traveling wave is affected by the smoothing reactor and DC filter at the end of the DC line, and there is a dead zone in the near zone

[0006] Therefore, the DC line distance measurement based on the transmission line traveling wave propagation characteristics is easily affected by the above factors, and the distance measurement accuracy is poor

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