Lightning stroke fault recognition method for EHV (extra-high voltage) DC transmission line based energy spectrum similarity

Abstract

The invention relates to a lightning stroke fault recognition method for an EHV (extra-high voltage) DC transmission line based energy spectrum similarity, and belongs to the technical field of power system relay protection. The method comprises the steps: extracting the ratio of a positive time domain waveform to an area formed by the enclosing of the zero axis of the positive time domain waveform and the ratio of a positive time domain waveform of any fault type to the area formed by the enclosing of the zero axis of the positive time domain waveform during stable operation when the voltage of the EHV DC transmission line fluctuates, and recognizing the fault and lightning stroke interference according to the ratios; switching to fault classification recognition if the interference is a fault, carrying out the wavelet decomposition recognition of an additional component through wavelet, and judging whether the fault is a grounding fault or a lightning stroke fault; and switching to a shielding failure and back flashover fault recognition if the fault is the lightning stroke fault. The method achieves the time frequency analysis of the simulation data, achieves the extraction of data in a short time period, and integrates area ratios, energy spectrum similarity and modular maximum value. The method achieves the extraction of a set of criteria for thunder interference, grounding faults, back flashover faults and shielding failures, and can achieve the accurate, quick and effective recognition of various types of conditions.

Description

technical field [0001] The invention relates to a lightning strike fault identification method for UHV DC transmission lines based on energy spectrum similarity, and belongs to the technical field of electric power system relay protection. Background technique [0002] Lightning strikes are the main cause of UHV transmission line tripping, and direct lightning strikes are more serious. In addition, my country's UHV DC transmission lines have long distances, wide distribution and complex and harsh natural conditions, which pose a major challenge to the protection of transmission lines. Lightning strike faults and ordinary faults have their own characteristics. How to use their characteristics as the basis for transient protection to accurately and quickly identify various types of faults is a very important issue. [0003] At present, many scholars at home and abroad have done a lot of research on this. Some scholars have proposed identification criteria for the transient c...

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Problems solved by technology

However, this criterion does not take into account the situation that the lightning fault is weak, which will cause the malfunction of the component, and there is a possibility of misjudgment

However, for the analysis of lightning interference, traveling wave of lightning strike faults and traveling wave waveform characteristics of short-circuit faults on UHVDC lines, the proposed method is still difficult to identify lightning strike faults and common short-circuit faults on UHVDC transmission lines. The inherent transient characteristics of the line under lightning strike still need further research

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