Fault branch identification method of three-terminal direct-current power-transmission-line discrete wavelet transformation and support vector machine

Abstract

The invention relates to a fault branch identification method of three-terminal direct-current power-transmission-line discrete wavelet transformation and a support vector machine and belongs to the electric power system fault range finding technology field. The method is characterized by setting fault positions in a three-terminal direct-current MT branch, an NT branch and a QT branch, setting a step length to be 1km and transition resistors to be 0omega, 10omega and 100omega respectively; secondly, defining a time window length to be 1ms, carrying out db4 wavelet decomposition on a measurement terminal current traveling wave, selecting a wavelet transformation coefficient under a second scale as an input attribute of the support vector machine SVM, establishing a SVM fault branch discrimination model, training the model, and defining that SVM output 1 is a QT branch fault, output 0 is a MT branch fault and output -1 is an NT branch fault; and finally, when a three-terminal direct-current line is generated, carrying out db4 wavelet decomposition on the current traveling wave and inputting the SVM, and according to an output result of the SVM, realizing determination of the fault branch.

Description

technical field [0001] The invention relates to a three-terminal direct current transmission line discrete wavelet transform and a fault branch identification method of a support vector machine, which belongs to the technical field of power system fault distance measurement. Background technique [0002] Multi-terminal flexible DC transmission is composed of three or more converter stations and the DC lines connecting them. In terms of economy, more DC transmission systems at both ends can save transmission corridors, reduce the number of high-cost converter stations, and effectively reduce investment costs and operating costs; in terms of flexibility, one or some converter stations can be made The flow station can be operated as a rectifier or as an inverter, and the power flow distribution can be adjusted through power reversal. Researching the fault location technology applicable to faulty branch identification of three-terminal DC transmission lines can effectively impr...

AI Technical Summary

Problems solved by technology

Conventional ranging is greatly affected by the operation mode and the accuracy of line parameters. The accuracy of traveling wave ranging is high, but it depends on the accurate time synchronization at both ends of the line, which is greatly affected by communication interference, and there will be dead zones at the beginning and end of the line.

When the fault occurs at the beginning and end of the line, due to the fast transmission speed of the traveling wave, the traveling wave detection and acquisition module in the traveling wave ranging Sometimes or when the communication at both ends of the line fails, the traveling wave distance measuring device cannot measure distance normally; when the traveling wave distance measuring device itself fails, the traveling wave distance measuring device will also lose its function

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