Mathematical statistic-based transformer direct current resistance change amount threshold value analysis method

Abstract

The invention discloses a method for analyzing a transformer winding and a sleeve direct-current resistance change amount threshold value by utilizing mathematical statistics. In order to accurately analyze the change quantity threshold value of the direct-current resistance of the transformer, the direct-current resistance data of the transformer is firstly sorted, and the variation of the direct-current resistance of the adjacent years is calculated; then, by combining a subjective representation method (distribution diagram and a Q-Q graph) with an objective hypothesis testing method (W checking, K-S checking and A-D checking), whether the direct-current resistance change quantity meets normal distribution or not is verified; and finally, if the direct-current resistance change quantitymeets normal distribution, the sample data mean value and the standard deviation are calculated, a normal distribution confidence interval is utilized and a certain margin condition is considered, and a direct current resistance variation threshold value under different voltage grades is determined. By analyzing the mathematical statistics result, the threshold value of the direct-current resistance change of the transformer under the difference condition can be judged, and reference is provided for operation and maintenance personnel.

Description

technical field [0001] The present application relates to the technical field of power equipment data analysis, and in particular to a threshold analysis method for transformer direct current resistance variation based on mathematical statistics. Background technique [0002] At present, the power network has developed into a cross-regional interconnected large power grid. As the energy conversion hub of the network, the transformer will seriously affect the stable operation of the power grid if it fails. Measuring the DC resistance of the winding and the bushing is a key item in the preventive test of the transformer. The integrity of the conductive circuit connection of the transformer can be judged through the test results, so as to detect and eliminate hidden dangers in time to ensure that the transformer is in good operation. However, in this test, due to the inconsistency of the test conditions on the test site (such as the difference in ambient humidity and insulating...

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Problems solved by technology

[0004] Aiming at the problems existing in the prior art, the present invention provides a method for analyzing the threshold value of transformer DC resistance variation based on mathematical statistics, in order to solve the problem that the threshold value stipulated in the current test regulations is too general, and there is still a lack of analysis methods for relevant differences. The method analyzes the problem of the difference of the threshold value of the DC resistance change of the transformer under different voltage levels, and the methods used include:

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