Time and frequency domain-combined tower fault locating method and system

Abstract

The invention provides a time and frequency domain-combined tower fault locating method. The time and frequency domain-combined tower fault locating method includes the following steps that: three-phase current in a fault is obtained, and transformation processing is performed on the three-phase current, so that linear mode and zero mode parameters are obtained; the main natural frequency values of fault traveling waves on a first busbar and a second busbar are determined, a first prediction value and a second prediction value which are respectively corresponding to distances from a fault point to the first busbar and the second busbar are obtained according to the linear mode and zero mode parameters; calculation values satisfying predetermined conditions are obtained according to the first prediction value and the second prediction value, and the initial wave head time of the first busbar and the second busbar is acquired, and first reflection wave time and second reflection wave time corresponding to the first busbar and the second busbar are further derived; based on a wavelet analysis method, the first reflection wave time and the second reflection wave time are revised respectively, and the revised first reflection wave time and the second reflection wave time are introduced into a preset formula, so that the actual values of the distances from the fault point to the first busbar and/or the second busbar are obtained. With the time and frequency domain-combined tower fault locating method provided by the embodiment of the invention adopted, influence of change of traveling wave speed and line length due to sags and differences of seasons, on distance measurement accuracy, can be eliminated, and distance measurement accuracy can be 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 tower fault location combined with time-frequency domain. 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. It is of great significance to reduce the time of power workers' line inspection and power outage and ensure the safe and reliable operation of the power grid. [0003] At present, the methods for fast and accurate fault location of transmission lines mainly include: parameter identification method, traveling wave method and natural frequency method based on the transient characteristics of fault signals. Among them, in the method of using the parameter identification method to locate the fault, it uses the p...

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Problems solved by technology

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, etc., so the distance measurement accuracy is often lower than that of the double-ended traveling wave method

In the fault location method using the natural frequency method, it is a fault location method that extracts the characteristic frequency components of the transient signal. The influence of confounding phenomenon leads to the decrease of ranging accuracy

[0004] In view of the above deficiencies, relevant scholars combined the characteristics of the existing traveling wave method and natural frequency method, and proposed a time-frequency composite single-ended fault location method integrating natural frequency method and traveling wave method. As a result, the single-ended traveling wave fault location is realized, which can accurately identify the nature of the traveling wave head, and has both the advantages of high ranging accuracy of the traveling wave method and stable ranging of the natural frequency method, but the disadvantage is that this method does not take into account the traveling wave The speed and the length of the line will vary with the sag and the season, and the impact on the ranging results; at the same time, the natural frequency method is the basis of the time-frequency combined ranging algorithm, and its ranging accuracy needs to be improved

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