JP4703223B2 - Degradation diagnosis method for oil-filled transformers - Google Patents

Description

The present invention relates to a method for diagnosing deterioration of an oil-filled transformer using a CO ₂ + CO method, a furfural method, a polymerization degree method, or the like.

  The life of an oil-filled transformer is determined mainly by a decrease in mechanical strength (decrease in average polymerization degree) of coil insulating paper. The life level of the coil insulating paper is an average polymerization degree of 450 according to the Japan Electrical Manufacturers Association standard (JEM standard) issued in 1993 (JEM 1463). Assuming that the degree is around 1000, the life of the oil-filled transformer is about 30 years. The average degree of polymerization means the average number of repeating hexagonal glucose rings in cellulose constituting the insulating paper.

  In such oil-filled transformers, reliability has improved due to advances in design and manufacturing technology and maintenance and inspection technology, and accidents that have occurred during their lifetime have been decreasing year by year. The impact of the case will be very large. From the viewpoint of detecting abnormalities at an early stage and preventing the occurrence of a major accident, the deterioration diagnosis of oil-filled transformers over 20 years old is performed. Is preferred.

The deterioration diagnosis of an oil-filled transformer is based on the correlation between the amount of this specific component and the average degree of polymerization of the coil insulating paper after collecting the insulating oil inside the transformer and analyzing the specific component in this insulating oil. Based on this, a method for estimating the average degree of polymerization of the coil insulating paper (for example, CO ₂ + CO method, furfural method) and an insulator (for example, press board, lead insulating paper) that can be collected inside the transformer are collected, and this By obtaining the average degree of polymerization of the insulator, it is roughly classified into a method for estimating the average degree of polymerization of the coil insulating paper (for example, the degree of polymerization method) (Non-Patent Document 1).

In the gas analysis in insulating oil, carbon monoxide (CO) and carbon dioxide (CO ₂ ) that appear in the insulating oil are also analyzed, and the amount of these (CO ₂ + CO) due to the decomposition components of the coil insulating paper deteriorates. Used for diagnosis. This is the CO ₂ + CO method. In the CO ₂ + CO method, for example, a correlation diagram between the amount of (CO ₂ + CO) and the average degree of polymerization of coil insulating paper as shown in FIG. 3 (a) is provided (Non-Patent Document 2). The average degree of polymerization of the coil insulating paper can be estimated from the relationship diagram. For example, when performing deterioration diagnosis on the safety side, if the amount of (CO ₂ + CO) exceeds 0.2 [ml / g], the average degree of polymerization is less than 450, and the oil-filled transformer has reached the end of its life. Become.

  In addition, furfural as an aldehyde component is generated during the decomposition process of cellulose constituting the coil insulating paper. Most of the generated furfural is adsorbed by insulating paper, but part of it is dissolved in insulating oil. The amount of furfural dissolved in this insulating oil is used for deterioration diagnosis. This is the furfural method. In the furfural method, for example, a correlation diagram between the amount of furfural and the average degree of polymerization of the coil insulating paper as shown in FIG. 3B is provided (Non-Patent Document 2). The average degree of polymerization can be estimated. For example, when performing deterioration diagnosis on the safe side, if the amount of furfural exceeds 0.0015 [ml / g], the average degree of polymerization is less than 450 and the oil-filled transformer has reached the end of its life.

  Furthermore, the degree of polymerization method is a method for collecting deterioration of the coil insulation paper by collecting a portion of the press board that does not affect the insulation from the inside of the transformer when the transformer is stopped, such as during open inspection. The method for measuring the average degree of polymerization is defined in JEM 1455 of the Japan Electrical Manufacturers' Association. The procedures are “dissolution”, “measurement of specific viscosity”, and “calculation of average degree of polymerization”. The polymerization degree method is a method for estimating the degree of deterioration of the coil insulating paper in the hot spot portion of the coil where the temperature is highest. In addition, as a method similar to the polymerization degree method, a method has been proposed in which lead insulating paper is taken instead of the press board and the degree of deterioration of the hot spot portion is estimated from the average polymerization degree. If there is no, it is called the polymerization degree method including both.

Technical Committee on Reliability Maintenance Technology for Aging Transformers, “Current Status and Trends of Reliability Maintenance Technology for Aging Transformers”, IEEJ Technical Report, IEEJ, March 2003, No. 922, p20-27 Power Transformer Maintenance Management Special Committee, “Maintenance management of oil-filled transformers”, Electric Cooperative Research, Electric Cooperative Research Group, February 1999, Vol. 54, No. 5 (Part 1)

However, each of these methods has advantages and disadvantages. In the CO ₂ + CO method and the furfural method, insulating oil can be collected even while the transformer is in operation, so there is no need to stop the operation of the transformer when diagnosing deterioration, and deterioration diagnosis can be performed at any time. Although it is easy to collect oil, there is an advantage of a simple and inexpensive method. However, since the degree of deterioration varies depending on the operating temperature condition of the oil-filled transformer, the accuracy of the diagnosis result is not good. Further, since the amount of (CO ₂ + CO) and the amount of furfural are different from the average degree of polymerization of the coil insulating paper, the accuracy of the diagnosis result is not good in this respect. These facts can be understood from the fact that the correlation diagram shown in FIG.

On the other hand, the degree of polymerization method is not the average degree of polymerization of coil insulating paper, but it measures the average degree of polymerization of press board and lead insulating paper with the same dimensions, so compared to the CO ₂ + CO method and the furfural method. It has the advantage of high accuracy in the diagnostic results and is an ideal method. However, the transformer must be disassembled as well as the sample cannot be taken unless the transformer is stopped. Therefore, it is a very expensive method and is not suitable for monitoring deterioration diagnosis (continuous deterioration diagnosis).

  Therefore, the present invention provides a method for diagnosing deterioration of an oil-filled transformer that can make use of the advantages of both, that is, can perform deterioration diagnosis simply and inexpensively and obtain a highly accurate diagnosis result. The task is to do.

The present invention collects insulating oil inside the oil-filled transformer at a predetermined point in time from the use of the oil-filled transformer to the end of its life, and analyzes CO ₂ and CO in the insulating oil. Based on the correlation between the amount of CO ₂ and CO and the average degree of polymerization of the coil insulating paper, the CO ₂ + CO method for estimating the average degree of polymerization of the coil insulating paper , or after analyzing the furfural in the insulating oil Based on the correlation between the amount of furfural and the average degree of polymerization of the coil insulating paper, the furfural method for estimating the average degree of polymerization of the coil insulating paper is used as a basis, and the same timing as the predetermined time point or a large time difference from that. At the time of opening inspection of the oil-filled transformer that is conducted during the period, the insulation that can be collected inside the oil-filled transformer is collected, and the average degree of polymerization of the insulation is obtained by calculating the average degree of polymerization of the insulation. Perform polymerization degree method to estimate The difference between the average degree of polymerization of the coil insulating paper estimated by the CO ₂ + CO method or the furfural method and the average degree of polymerization of the coil insulating paper estimated by the polymerization degree method is obtained, and based on the difference, CO ₂ and CO The amount of furfural or the amount of furfural and the average degree of polymerization of the coil insulating paper are corrected, and on the basis of this optimized correlation , the CO ₂ + CO method or the furfural method is performed regularly or irregularly. Thus, the average polymerization degree of the coil insulating paper is monitored.
In this case, the diagnosis is not good accurate results, easily and inexpensively with a basic CO ₂ + CO method or furfural method can be carried out, CO ₂ + CO method or the disadvantages of furfural method the accuracy of the diagnosis result high degree of polymerization By supplementing with the method, it is intended to improve the accuracy of the diagnostic result in the CO ₂ + CO method or the furfural method. That is, the correlation between the amount of the specific component and the average degree of polymerization of the coil insulating paper in the CO ₂ + CO method or the furfural method is likely to have an error. The difference between the average degree of polymerization of the coil insulating paper obtained from this and the average degree of polymerization of the coil insulating paper obtained by carrying out the CO ₂ + CO method or the furfural method at that time or while not greatly deviating from the above is obtained. and correcting the correlation as an error included in the correlation, based on the optimized correlation relationship, if we go to CO ₂ + CO method or furfural process, even CO ₂ + CO method or furfural method, A highly accurate diagnosis result can be obtained.

In addition, according to the present invention, at the time of opening inspection of the oil-filled transformer performed in the monitoring process by the CO ₂ + CO method or the furfural method after correcting the correlation , the degree of polymerization is performed to correct the correlation again. Such a method can also be adopted .
Further, as the insulator, a line lead which is provided at a position near the hot spot portion having the highest temperature of the coil of the oil-filled transformer and whose average polymerization degree can be regarded as the average polymerization degree of the coil insulating paper. It is preferable to select insulating paper .

The correction of the correlation is, for example, CO ₂ In the correlation diagram showing the correlation between the amount of CO and the amount of furfural and the average degree of polymerization of the coil insulating paper, the curve shown in the correlation diagram is shift-corrected based on the difference.

As described above, according to the present invention, the base is by taking the CO ₂ + CO method or furfural method, simple and inexpensive to be carried out degradation diagnosis, moreover, CO ₂ + CO method of poor accuracy of the diagnosis results Alternatively , by compensating for the shortcomings of the furfural method with a polymerization degree method with high accuracy of the diagnostic result, a highly accurate diagnostic result can be obtained even with the CO ₂ + CO method or the furfural method .

  Hereinafter, an oil-filled transformer deterioration diagnosis method according to an embodiment of the present invention will be described with reference to FIG. In addition, although the timing which starts the deterioration diagnosis method of the oil-filled transformer which concerns on this embodiment is not specifically limited, since it is preferable to perform the deterioration diagnosis of the oil-filled transformer which passed about 20 years or more, oil It shall start 20 years after using the transformer.

First, the insulating oil inside the transformer is sampled (S1), and the amount of (CO ₂ + CO), which is a specific component in this insulating oil, is analyzed (S2), and then from the obtained (CO ₂ + CO) amount Based on the correlation diagram shown in FIG. 3A, the average degree of polymerization of the coil insulating paper is estimated (S3). That is, the CO ₂ + CO method is performed (S1 to S2), and the average degree of polymerization of the coil insulating paper is estimated (S3).

  In addition, the line lead insulating paper is sampled at the same timing or at the timing of open inspection or the like that is performed without much time difference (S4), and the average degree of polymerization of the line lead insulating paper is calculated (S5). Then, the average polymerization degree of the coil insulating paper is estimated from the obtained average polymerization degree of the line lead insulating paper (S6). That is, the polymerization degree method is performed (S4 to S5), and the average polymerization degree of the coil insulating paper is estimated (S6). Since the line lead is provided near the hot spot portion of the oil-filled transformer, the average degree of polymerization of the line lead insulating paper can be regarded as the average degree of polymerization of the coil insulating paper or is small. Just temperature correction.

  Next, a difference d between the average degree of polymerization of the coil insulating paper estimated in S3 and the average degree of polymerization of the coil insulating paper estimated in S6 is calculated (S7), and FIG. The correlation diagram shown in (a) is corrected (S8). For example, if the average degree of polymerization of the coil insulating paper estimated in S6 is larger than the average degree of polymerization of the coil insulating paper estimated in S3, it is actually larger than the correlation diagram shown in FIG. As shown in FIG. 2 (a), correction (from broken line to solid line) is performed, and the average degree of polymerization of the coil insulating paper estimated in S3 is assumed. If the average degree of polymerization of the coil insulating paper estimated in S6 is smaller, it is assumed that the deterioration of the coil insulating paper has actually progressed more than the correlation diagram shown in FIG. (B) Correction (from broken line to solid line) is performed.

In the CO ₂ + CO method, as described above ([Problem to be solved by the invention] column), the degree of deterioration of the coil insulating paper varies depending on the operating temperature condition of the oil-filled transformer, and is measured (CO ₂ + CO ) The amount is different from the average degree of polymerization of the coil insulation paper, and as shown in FIG. 3 (a), the correlation diagram itself is wide, so the accuracy of the diagnosis result is not good. . The essence of this embodiment is that the correlation diagram is optimized by actually measuring the average degree of polymerization of the line lead insulating paper having the same dimension as the coil insulating paper and correcting based on this. By the way.

  Moreover, as described above ([Background Art] column), the life of the oil-filled transformer is mainly determined by a decrease in mechanical strength of the coil insulating paper (decrease in average polymerization degree). Precisely speaking, it can be said that it is determined by a decrease in the average polymerization degree of the coil insulating paper in the hot spot portion of the coil where the temperature is the highest, which is the weak point of the oil-filled transformer. In this embodiment, the position close to the hot spot portion. Since the average degree of polymerization is measured by collecting the line lead insulating paper provided in the above, it can be said that the reliability of the correlation diagram is highly reliable.

Then, after that, the CO ₂ + CO method is carried out regularly or irregularly, and the average degree of polymerization of the coil insulating paper is monitored (S9). Thus, while compensating disadvantages of CO ₂ + CO method, it is possible to benefit from the advantages of CO ₂ + CO method. That is, according to the present embodiment, by adopting the CO ₂ + CO method as a basis, deterioration diagnosis can be performed easily and inexpensively, and the degree of polymerization method is performed on the way and the correlation in the CO ₂ + CO method is performed. By correcting the relationship, a highly accurate diagnosis result can be obtained even with the CO ₂ + CO method.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

For example, in the above embodiment, the CO ₂ + CO method is employed, but instead of this, the furfural method may be employed, or both may be used in combination.

  In the above embodiment, the line lead insulating paper is collected as the polymerization degree method, but tap lead insulating paper or a press board may be collected. However, since the tap lead is provided at a position away from the hot spot portion of the oil-filled transformer, in order to increase the reliability of optimization of the correlation diagram, the tap lead insulating paper and the coil insulating paper It is important to optimize the temperature correction process.

Moreover, in the said embodiment, although the polymerization degree method is implemented only once, it is not limited to this. For example, if open inspection is scheduled in the monitoring process using the corrected CO ₂ + CO method, the correlation diagram is corrected again by performing the polymerization method at that time, thereby further optimizing the correlation diagram. Can be achieved.

  Moreover, in the said embodiment, although the correlation diagram provided by the nonpatent literature 2 is used, it is not limited to this, It is known provided by other academic societies, a transformer maker, an insulating paper maker, etc. It is also possible to use a correlation diagram of

  The correlation according to the present invention is not limited to these correlation diagrams, but may be a correlation formula provided by an academic society, a transformer manufacturer, an insulating paper manufacturer, or the like.

The flowchart of the deterioration diagnostic method of the oil-filled transformer which concerns on this embodiment is shown. It corrected by the degradation diagnostic method for an oil-filled transformer according to the embodiment, showing a correlation graph showing the relationship between (CO ₂ + CO) quantity and average polymerization degree of the coil insulating paper. (A) is a correlation diagram between the amount of (CO ₂ + CO) provided by the Electric Cooperative Research Group and the average degree of polymerization of the coil insulating paper, and (b) is the amount of furfural provided by the Electric Cooperative Research Group. And a correlation diagram between the average degree of polymerization of the coil insulating paper.

Claims (4)

At a given point during from using oil-filled transformers up to lifetime, in terms of the oil-filled transformer in the insulating oil was sampled and analyzed for CO ₂ and CO of the insulating oil, the CO ₂ And the CO ₂ + CO method for estimating the average degree of polymerization of the coil insulating paper based on the correlation between the amount of CO and the average degree of polymerization of the coil insulating paper , or analyzing the furfural in the insulating oil, Based on the correlation between the amount and the average degree of polymerization of the coil insulating paper, the Furfural method is used to estimate the average degree of polymerization of the coil insulating paper. in overhaul inspection time of dividing the oil-filled transformer, the oil-filled transformer internal harvestable insulator was collected, by obtaining the average polymerization degree of the insulating material, the degree of polymerization of estimating an average degree of polymerization of the coil insulating paper Do the law and CO ₂ The difference between the average polymerization degree of the coil insulating paper estimated by the + CO method or the furfural method and the average polymerization degree of the coil insulating paper estimated by the polymerization degree method is obtained, and the amount of CO ₂ and CO or furfural is calculated based on the difference. The coil insulation is corrected by correcting the correlation between the amount of copper and the average degree of polymerization of the coil insulating paper , and then performing the CO ₂ + CO method or the furfural method regularly or irregularly based on this optimized correlation. A method for diagnosing deterioration of an oil-filled transformer, characterized by monitoring an average degree of polymerization of paper. _{2. The} oil according to claim 1, wherein the degree of polymerization is again corrected by performing the polymerization degree method at the time of opening inspection of the oil-filled transformer performed in the monitoring process by the CO ₂ + CO method or the furfural method after correcting the correlation. Degradation diagnosis method for input transformer. The insulation is provided at a position near the hottest hot spot portion of the coil of the oil-filled transformer, and the line lead insulation paper whose average polymerization degree can be regarded as the average polymerization degree of the coil insulation paper. The deterioration diagnosis method for an oil-filled transformer according to claim 1 or 2. Correcting the correlation means CO ₂ 2. A correlation diagram showing the correlation between the amount of CO and the amount of furfural and the average degree of polymerization of the coil insulating paper, wherein the curve shown in the correlation diagram is shift-corrected based on the difference. 4. The deterioration diagnosis method for an oil-filled transformer according to any one of items 1 to 3.

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