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Novel multistage fault diagnosis method for power transformer

A technology for power transformers and fault diagnosis, which is applied in the measurement of electrical variables, instruments, and electrical measurement, etc., can solve the problems of lack of objectivity and heavy subjectivity, and achieve the goal of increasing analyzability, reducing uncertainty, and resolving conflicts and conflicts. Effect

Inactive Publication Date: 2015-05-27
STATE GRID CORP OF CHINA +3
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, if you directly assign BPA, the subjectivity is too heavy; if you assign the processed neural network output to BPA, the reliability coefficient is still an empirical value
The methods mentioned above all have certain limitations, and the method of determining BPA through expert experience lacks objectivity

Method used

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  • Novel multistage fault diagnosis method for power transformer
  • Novel multistage fault diagnosis method for power transformer
  • Novel multistage fault diagnosis method for power transformer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach

[0042] The present invention is mainly used for fault diagnosis of power transformers, and the specific implementation methods are as follows:

[0043] exist figure 2 Among them, step 1, the determination of the power transformer fault type. Assume It is a collection of transformer fault types. Practice shows that: transformer internal faults can be divided into overheating faults and discharge faults according to their nature. The statistical results of relevant literature on the types of oil-filled electrical equipment failures are shown in Table 2:

[0044] Fault type Taiwan ratio / (%) overheating failure 226 53.0 High Energy Discharge Fault 65 18.1 Overheating and high energy discharge fault 36 10.0 spark discharge failure 25 7.0 Moisture or partial discharge failure 7 1.9

[0045] Therefore, the transformer primary fault can be defined as:

[0046]

[0047] In the formula: f 0 It is an overheating fault; f 1...

example 2

[0076] On June 2, 2006, the 1# main transformer of 35KV Chengnan Substation was put into operation.

[0077] ; ; ; ; .

[0078] The three ratio codes are 1, 0, 0, and the preliminary diagnosis is arc discharge. However, using the method of this paper for diagnosis, the results are shown in Table 3:

[0079] Table 3 Diagnosis results of Example 2

[0080]

[0081] It can be seen from Table 3 that the mass value of other faults is the largest, so this type of fault is considered to be other faults. During the actual maintenance, no abnormality was found in the conventional electrical test of the transformer. After the oil was drained, it was found that one of the three fixing screws of the shielding cover at the end of the bushing was loose, but there was no obvious discharge trace. After tightening, the oil was degassed. The chromatographic analysis of the main transformer test run is normal.

example 3

[0083] Taihu Substation 110kV#2 main transformer rated capacity is 31500 kVA, rated voltage is 110 kV / 38 kV / 11 kV, model is SFSLZB-31500 / 110, it was put into operation in December 1997, on February 26, 2009, the Taihu Substation 110kV The #2 main transformer conducts periodic oil sample collection. Through oil chromatographic analysis, it was found that the test data of the oil sample of the main transformer body was abnormal, the content of acetylene increased greatly, and the content of other gases also increased in different ranges. The gas component content in the oil at that time was:

[0084] ; ; ; ; .

[0085] The three ratios are coded as 0, 2, 2, and the initial diagnosis is high temperature overheating (>700oC). However, using the method of this paper for diagnosis, the results are shown in Table 4:

[0086] Table 4 Diagnosis results of Example 3

[0087]

[0088] It can be seen from Table 4 that t...

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Abstract

The invention provides a novel multistage fault diagnosis method for a power transformer. The method uses two primary algorithms including a posterior probability support vector machine (SVM) and an evidence theory, and realizes fault diagnosis on the transformer. For a to-be-detected sample, firstly, the to-be-detected sample is preprocessed with a codeless four-ratio method and a characteristic gas method, and two sets of characteristic vectors can be generated; secondly, basic probability assignment (BPA) is provided for the evidence theory by utilizing one-to-one posterior probability estimation of various SVMs; finally, a multistage comprehensive diagnosis system is created. The method can fully utilize redundant or complementary information of chromatographic data and solves a problem of uncertainty between a fault mode and fault characteristics; at the same time, the analyzability of the system can be improved, the identification capability of the fault mode is effectively improved, and the accuracy and reliability of a diagnosis result can be remarkably improved in comparison with those of a conventional diagnosis result.

Description

technical field [0001] The invention relates to a novel multi-level fault diagnosis method for power transformers. Background technique [0002] The power transformer is an important equipment in the power system. Once a failure occurs, it will cause huge economic losses. Therefore, the fault diagnosis of power transformer plays a very important role in the safe operation of power system. Due to the complex structure of power transformers, there are many uncertain factors involved in faults, and the faults reflected by traditional characteristic signals (such as oil chromatography, dielectric loss, iron core ground current, partial discharge, etc.) have great limitations. Therefore, it is urgent to study some new intelligent algorithms applied to the fault diagnosis of power transformers. [0003] For many years, the dissolved gas analysis technique in oil (DGA) is suitable for the on-line monitoring of power transformers and has the advantages of good analysis results. It...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/00
Inventor 孙志何菲梅军
Owner STATE GRID CORP OF CHINA
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