A method for identifying lightning strike interference in HVDC transmission lines

Abstract

The invention discloses a method for identifying lightning strike interference of a high-voltage direct current transmission line. First, phase-mode transformation is performed on the positive and negative voltage and current signal fault components of the rectifier side to obtain a 1-mode component; secondly, a voltage 1-mode component within 3 ms after the protection is activated is performed. The components are CEEMD-HHT transformed to calculate the low-frequency energy and high-frequency energy; then the ratio of the voltage low-frequency energy to the high-frequency energy is calculated, and according to the result, it is judged whether lightning strike interference or line fault has occurred; finally, if lightning strike disturbance occurs, the protection is reset. If there is a fault, perform CEEMD-HHT transformation on the 1-mode component of the current 1ms after the protection starts, calculate the ratio of the low-frequency energy to the high-frequency energy of the current, and judge whether a lightning strike fault or a common short-circuit fault has occurred according to the result, and protect the outlet. The invention can accurately identify the lightning strike interference, improve the reliability of the DC line transient protection, further distinguish the lightning strike fault and the common short-circuit fault, and has guiding significance for the 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. Background technique: [0002] As an effective way to solve the 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, but the high-frequency signal injected when the line is struck by lightning easily affects the protection based on transients. In view of the above problems, fast and reliable anti-lightning interference technology is required to accurately...

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 EMD-HHT are usually used to effectively extract the difference in energy distribution of interference and fault spectrum. Aliasing

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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