Generalized S transformation-based lightning interference identification method for high-voltage direct-current transmission line

Abstract

The invention discloses a generalized S transformation-based lightning stroke interference identification method for a high-voltage direct-current transmission line. Themethod comprises the steps: firstly carrying out phase-mode transformation on positive and negative voltage and current signal fault components of a rectification side, and obtaining a 1-mode component; secondly, carrying out generalized S transformation on a voltage 1-mode component within 3 ms after protection is started, and calculating low-frequency energy and high-frequency energy; then calculating the ratio of low-frequency energy to high-frequency energy of the voltage, and judging whether lightning interference or a line fault occurs according to a result; and finally, if lightning stroke interference occurs, resetting protection, and if a fault occurs, performing generalized S transformation on a current 1-mode component 1ms after protection is started, calculating the ratio of low-frequency energy to high-frequency energy of the current, judging whether a lightning stroke fault or a common short-circuit fault occurs according to a result, and protecting an outlet. According to the method, lightning stroke interference can be accurately identified, the reliability of transient state quantity protection of the DC line is improved, a lightning stroke fault and a common short-circuit fault are further distinguished, and the method has guiding significance in lightning protection, operation and maintenance of the line.

Description

technical field [0001] The invention belongs to the field of power systems, relates to the field of relay protection of high-voltage direct current transmission lines, and in particular relates to a method for identifying lightning strike interference of high-voltage direct current transmission lines based on generalized S-transformation. Background technique [0002] As an effective way to solve the problem of power transmission, HVDC transmission has the advantages of low line cost, simple structure, large transmission capacity, small loss, and long transmission distance. It is also widely used in grid connection and urban cable power supply. The protection principle based on transients only needs single-ended fault information, and is often used as the main protection of the line. However, the high-frequency signal injected when the line is struck by lightning can easily affect the protection based on transients. In view of the above problems, fast and reliable anti-ligh...

AI Technical Summary

Problems solved by technology

Among them, the operation of extracting numerical features in the time domain is simple, but its threshold is easily affected by lightning parameters, and has the defect of being difficult to set, while the extraction of waveform features needs to be based on a long time window, which is difficult to cooperate with ultra-high-speed transient protection

In the frequency domain, methods such as wavelet transform and HHT are usually used, which can effectively extract the difference in energy distribution of interference and fault spectrum. However, the selection of wavelet base and the determination of parameters in the former have strong experience, while the latter has unavoidable modal aliasing. Phenomenon

The artificial intelligence method avoids complex mathematical operations, and the purpose of distinguishing interference and faults can be achieved through offline learning of the training set, but there are few actual examples that can be used as the training set, and it needs to be based on a large number of simulation results. May not be applicable in actual power system

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