Method for evaluating partial discharge state of oil paper insulation of converter transformer

Abstract

The invention relates to a converter transformer oil paper insulation partial discharge state evaluation method. The method comprises the following steps: S1, collecting a partial discharge signal; s2, establishing a partial discharge analysis mode three-dimensional spectrogram based on the phase, the time difference and the discharge repetition rate; s3, performing one-dimension and principal component analysis on a spectrogram matrix; s4, establishing a random forest classification model; and S5, evaluating the discharge state. The invention aims to provide the method for evaluating the partial discharge state of the oil paper insulation of the converter transformer, which can improve the adaptability of a detection method for evaluating the partial discharge state of the converter transformer under the AC / DC composite voltage and a discharge equivalent model and enhance the reliability of insulation state monitoring.

Description

technical field [0001] The invention relates to the field of partial discharge detection of power equipment, in particular to a method for evaluating the partial discharge state of oil-paper insulation of a converter transformer. Background technique [0002] At present, with the rapid growth of electricity demand, in many countries and regions around the world, UHV DC transmission systems have advantages in terms of high capacity and low loss, especially in China, which has a large area and an uneven population distribution, in addition to traditional fossil fuel power generation In addition, new energy power generation bases such as wind energy and solar energy are also far away from the load center. Therefore, there is an imbalance between power load and power generation. Equipment and converter transformers bear important operational responsibilities, so their insulation status is particularly important to the safe operation of the system. The valve side windings of the ...

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Problems solved by technology

[0005] Under AC-DC composite voltage, both AC and DC voltage components will affect the characteristics of partial discharge, so various parameters can be obtained for partial discharge under AC-DC composite voltage, such as discharge volume, discharge phase, discharge time interval and equivalent frequency, etc. , and the ratio of AC and DC components has a great influence on the discharge characteristics, but the influence of test conditions on the partial discharge will lead to poor repeatability of the test results, and the partial discharge needs to be calibrated in the mode of using the apparent discharge , limited by the partial discharge detection method

At the same time, the normalization of the discharge value during the discharge process generally requires the use of the maximum and minimum value normalization method. In the case of differences in the discharge equivalent models, the reference value of the discharge value of each model is low, and the entire process of discharge development The upper limit of the medium discharge capacity is difficult to determine in the actual operation of electrical equipment, which limits the normalized application of the discharge capacity

[0006] Therefore, for the AC-DC composite voltage environment of the converter transformer, the traditional partial discharge identification method based on the discharge amount under pure AC and pure DC voltage is not applicable, and a new partial discharge evaluation method needs to be provided to break the limitation of the traditional method , can accurately calibrate the partial discharge of the converter transformer, and overcome the problem that the apparent discharge value is difficult to normalize between different equivalent discharge models and discharge development stages

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