A method and system for double-terminal traveling wave fault location based on wavelet analysis

Abstract

The invention provides a wavelet analysis-based double-end traveling-wave fault locating method. The method comprises the steps of firstly, acquiring a three-phase current during the occurrence of a fault and obtaining parameters in the line mode and in the zero mode after the transformation processing of the three-phase current; secondly, conducting the wavelet decomposition on the three-phase current to reconstruct the three-phase current, and conducting the self-correlation analysis on the current to obtain self-correlation function waveforms formed by a first bus and a second bus respectively; thirdly, screening out a waveform that meets a preset condition and adopting the waveform as a first waveform, and adopting a waveform that does not meet the preset condition as a second waveform; fourthly, acquiring the overall length of a power transmission line, the abscissa time of the first waveform that reaches a maximum value point last time, the abscissa time of the second waveform that reaches a maximum value point last time, and the abscissa time of the second waveform that reaches a third maximum value point last time; fifthly, when the difference between the abscissa time of the first waveform that reaches the maximum value point last time and the abscissa time of the second waveform that reaches the third maximum value point last time is within a preset range, obtaining a distance value between a fault point and the first and / or second bus(es).according to the method, the traveling wave velocity and the line length variation do not need to be considered at all. Meanwhile, the two-terminal accurate synchronism is also not required. Therefore, the distance measurement reliability and the distance measurement accuracy are improved.

Description

technical field [0001] The invention relates to the technical field of transmission line fault location, in particular to a method and system for double-terminal traveling wave fault location based on wavelet analysis. Background technique [0002] With the rapid development of my country's electric power industry and the construction of a large number of high-voltage long-distance transmission lines, various short-circuit faults have a great impact on the reliability of power supply. Reduce the difficulty of manual line inspection, and can reduce the loss caused by power outages. [0003] Generally, there are two main methods for fault location in power systems: impedance calculation method and traveling wave method. In the method of locating faults using the impedance calculation method, it calculates the impedance of the fault circuit based on the voltage and current measured when the transmission line is faulty to locate the fault, but this method is limited by the type ...

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Problems solved by technology

In the method of locating faults using the impedance calculation method, it calculates the impedance of the fault circuit based on the voltage and current measured when the transmission line is faulty to locate the fault, but this method is limited by the type of fault, fault resistance, and line-to-end The impact of load impedance is great, and the error is large, and it is difficult to meet the requirements of actual operation in terms of accuracy by using impedance method for distance measurement during high-resistance faults and flashover faults

Among the fault location methods using the traveling wave method, it includes the single-ended method and the double-ended method; among them, the double-ended method can realize accurate fault location according to the initial wave head time at both ends of the line, but this method relies on the precise synchronization of both ends, Therefore, a dedicated synchronous clock unit (such as GPS and Beidou satellite positioning system) is required; the single-ended method can be positioned only by using the traveling wave characteristics at one end of the line, which is simple to implement, but in this method, due to the identification of the nature of the reflected wave head, it is affected by the transition resistance. Arc characteristics, system operation mode, load current and other influences make the distance measurement accuracy often lower than the double-ended traveling wave method based on wavelet analysis

[0004] In view of the above deficiencies, relevant scholars use wavelet analysis to analyze the characteristics of fault traveling waves, and propose the following two solutions: 1. Determine the arrival time of fault traveling waves by extracting the position of fault traveling wave feature points through wavelet transform, and take into account the propagation speed of fault traveling waves The problem of changing, but the disadvantage is: this method needs to draw the phase velocity frequency curve to determine the wave velocity, which increases the workload, and lacks consideration of the influence of the line length change on the distance measurement; The corresponding points of the modulus maxima on both sides are used to determine the moment when the fault traveling wave reaches the bus, and the polarity comparison method is used to identify the fault point and the reflected wave of the adjacent bus. The discriminant method is prone to failure

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