Quantitative method for furan concentration, transformer degradation diagnosis method using the method and device thereof

Abstract

A method for quantifying the furan concentration of a transformer deterioration state for effective on-site management is disclosed. The method for quantifying the furan concentration comprises: mixing a color reagent in an extraction solution for extracting furan from an insulating oil sample to react, and measuring the degree of color development of the extraction solution; and quantifying the furan concentration by correcting the degree of color development of the extraction solution based on the correlation between precise analysis and simple analysis. In this case, the precise analysis may be an analysis using high performance liquid chromatography (HPLC) performed in a laboratory to analyze furan compounds in transformer insulating oil and obtaining a quantitative value by column separation, and the simple analysis may be an analysis of the chromaticity value of an actual transformer sample obtained on-site.

Description

Technical Field

[0001] The present invention relates to a method for quantifying furan concentration, a method for diagnosing transformer degradation using the method and a device thereof, and more particularly to a method for quantifying furan concentration of an insulating oil sample collected from a transformer and diagnosing the degradation state of the transformer using the quantified furan concentration so as to effectively manage the degradation state of the transformer on site, a method for diagnosing transformer degradation using the method and a device thereof (METHOD FOR QUANTIFYING OF FURANCONCENTRATION, METHOD AND APPARATUS FOR DIAGNOSING TRANSFORMER DETERIORATION USING THE SAME).

[0002] The present invention claims priority from Korean Patent No. 10-2019-0102500, filed on August 21, 2019, the disclosure of which is incorporated herein by reference. Background Art

[0003] Typically, the life of a transformer is limited by the aging or degradation of the insulating paper wound on the transformer windings. However, it is practically impossible to inspect the inside of the transformer directly, so an indirect method for evaluating the insulating paper inside the transformer is needed.

[0004] Insulation paper is made of cellulose. Since the main component unit of cellulose is a single molecule of glucose, a pentagonal furan compound is generated through a condensation reaction.

[0005] Insulating oil begins to thermally decompose when the boiling point is above 400°C. As the temperature rises, this decomposition increases, producing deterioration products such as furfural (2-furaldehyde), which is a furan compound. At this time, the main gases produced are low molecular weight hydrocarbons such as CH4, C2H6, C2H4, and hydrogen (H2) that are highly soluble in insulating oil.

[0006] On the other hand, in order to analyze furan compounds in transformer insulating oil, high performance liquid chromatography (HPLC) is usually used. After furan is first extracted from the oil, HPLC is used to analyze while the mobile phase solvent is flowing. This analysis method is a classic organic compound analysis method. Since it requires expensive equipment and skilled professionals, it has the disadvantages of being time-consuming and difficult to maintain. In other words, this analysis method cannot be used for direct diagnosis on site.

[0007] Therefore, a furan diagnostic device has been proposed that can be used on site by non-professionals by using an analytical method using a chemical reaction of a furan compound and aniline acetate. This furan diagnostic device can quantify the furan concentration using the degree of color development of a pink complex generated by a color development reaction of a furan compound and aniline acetate, and can diagnose the deterioration of an old transformer.

[0008] However, the simple analysis method using the color reaction is used as a method of visually observing the color or performing screening when the concentration reaches a predetermined concentration or above. This qualitative method cannot replace the quantitative analysis method compared with the laboratory analysis method.

[0009] Conventionally, when using a commercial colorimeter, it is possible to calibrate using a standard substance and then perform quantification. However, if the manufacturer cannot insert a calibration program, there is a disadvantage that a program that exports data to an external source for quantification must be used.

[0010] In addition, when non-professionals use the furan diagnostic device, the meaning of the quantitative furan concentration value cannot be clearly understood.

[0011] Therefore, existing furan diagnostic devices require the selection of optimal color development wavelength and calibration algorithms to measure accurate concentrations. Summary of the invention

[0012] Technical problem to be solved by the invention

[0013] The object of the present invention is to provide a method for quantifying the furan concentration of an insulating oil sample collected from a transformer and diagnosing the deterioration state of the transformer using the quantified furan concentration so as to effectively manage the deterioration state of the transformer on site, a transformer degradation diagnosis method using the method, and a device thereof.

[0014] Means for solving technical problems

[0015] The method for quantifying furan concentration in an embodiment of the present invention includes: mixing a color developing reagent in an extraction solution for extracting furan from an insulating oil sample to react, and measuring the color development degree of the extraction solution; and quantifying the furan concentration by correcting the color development degree of the extraction solution based on the correlation between precise analysis and simple analysis, wherein the precise analysis is an analysis using high performance liquid chromatography (HPLC) performed in a laboratory to analyze furan compounds in transformer insulating oil and obtaining quantitative values ​​through column separation, and the simple analysis is an analysis of the chromaticity value of an actual transformer sample obtained on site.

[0016] The extraction solution may be a layer formed at the bottom of the insulating oil sample after the insulating oil sample is mixed with the extraction solvent and the sample is allowed to stand in a vertical direction.

[0017] The insulating oil sample and the extraction solvent may be mixed by a sample mixer at 90 degrees to the left and right for 1 minute or 50 times.

[0018] The ratio of aniline to acetate in the color developing reagent may be 1:6.

[0019] The ratio of the extraction solution to the color developing reagent is 1:1.5, and the reaction time of the extraction solution and the color developing reagent can be 4 minutes.

[0020] The measuring the color development degree of the extraction solution may be measuring the color development degree of the extraction solution in a wavelength region of 520 nm and 530 nm.

[0021] In the correlation between the precise analysis and the simple analysis, the confidence can be verified by Pearson correlation analysis using the Pearson correlation coefficient (r) calculated by the following formula,

[0022] Mode:

[0023] (in, The two variables x and y are linearly related.

[0024] In addition, the transformer degradation diagnosis method of the embodiment of the present invention may include: a step of quantifying the furan concentration of the insulating oil sample collected through the transformer; and a step of diagnosing the degradation state of the transformer using the quantified furan concentration based on the correlation between the furan concentration and the degree of polymerization of the insulating paper.

[0025] In the quantitative method, a color developing reagent is mixed in an extraction solution for extracting furan from an insulating oil sample to react, and the color development degree of the extraction solution is measured; and the concentration of furan is quantified by correcting the color development degree of the extraction solution based on the correlation between precise analysis and simple analysis, wherein the precise analysis is an analysis using high performance liquid chromatography (HPLC) performed in a laboratory to analyze furan compounds in transformer insulating oil and obtaining quantitative values ​​through column separation, and the simple analysis is an analysis of the chromaticity value of an actual transformer sample obtained on site.

[0026] In the diagnosis step, the deterioration state of the transformer with respect to furan concentration may be diagnosed by a Chendong model representing a correlation between furan concentration and a degree of polymerization of insulation paper.

[0027] In the diagnosis step, step-by-step diagnosis results may be provided based on the furan concentration at which the degree of polymerization of the insulation paper drops below 50%.

[0028] The diagnosis results can be provided by the distribution transformer and the transmission transformer respectively.

[0029] In addition, the transformer degradation diagnosis device of the embodiment of the present invention includes: at least one processor; and a memory for storing computer-readable instructions; when the instructions are executed by the at least one processor, the transformer degradation diagnosis device can perform: quantitatively determining the furan concentration of the insulating oil sample collected through the transformer, and based on the correlation between the furan concentration and the degree of polymerization of the insulating paper, using the quantitative furan concentration to diagnose the degradation state of the transformer.

[0030] When the instruction is executed by the at least one processor, the transformer degradation diagnosis device can be caused to perform the following steps: when quantifying the furan concentration, a color developing reagent is mixed in an extraction solution for extracting furan from an insulating oil sample to react, and the degree of color development of the extraction solution is measured; and the furan concentration is quantified by correcting the degree of color development of the extraction solution based on a correlation between a precise analysis and a simple analysis, wherein the precise analysis is an analysis in which a quantitative value is obtained by using high performance liquid chromatography (HPLC) performed in a laboratory in order to analyze furan compounds in the transformer insulating oil and by column separation, and the simple analysis is an analysis in which a chromatic value of an actual transformer sample is obtained on site.

[0031] The extraction solution is a layer formed at the bottom of the insulating oil sample after the insulating oil sample is mixed with the extraction solvent and is left to stand in a vertical direction. The transformer degradation diagnosis device may also include a sample mixer for mixing the insulating oil sample with the extraction solvent at 90 degrees to the left and right for 1 minute or 50 times.

[0032] According to an embodiment, the transformer degradation diagnosis device may further include a display for displaying the quantitative furan concentration and a step-by-step diagnosis result based on the quantitative furan concentration.

[0033] Effects of the Invention

[0034] In the present invention, the furan concentration of the insulating oil sample collected from the transformer is quantified, and the deterioration state of the transformer is diagnosed using the quantified furan concentration, so that the deterioration state of the transformer can be effectively managed on site.

[0035] Furthermore, in the present invention, instead of making a qualitative comparison with the naked eye according to the chromaticity change at each concentration level, the furan in the insulating oil can be quantified to diagnose the degradation state by additionally providing a diagnostic standard for power transmission and distribution transformers of various voltages.

[0036] Furthermore, in the present invention, degradation products used for soundness evaluation due to extension of the life limit of a long-term operating transmission and distribution transformer can be accurately quantified, and the degradation state of the transformer can be ultimately diagnosed by applying a diagnosis algorithm for each voltage.

[0037] Furthermore, in the present invention, an algorithm capable of indirectly predicting the degree of polymerization of insulating paper used for degradation assessment of old transformers may be included, and factors that hinder diagnostic accuracy due to methods with high human uncertainty may be removed by a screening method that performs diagnosis based on a colorimetric table using only chromaticity values.

[0038] Furthermore, in the present invention, non-professionals can also confirm the diagnosis results through the improvement of analysis accuracy and the diagnostic algorithm that can predict the degree of polymerization.

[0039] Furthermore, in the present invention, it is possible to significantly improve transformer management while ensuring competitiveness in diagnostic accuracy while being quickly and easily used on site.

[0040] Furthermore, in the present invention, the efficiency of on-site diagnosis can be improved by reducing the unit cost to about 1 / 5 compared with laboratory analysis, and the accuracy can be improved and a diagnostic algorithm can be provided compared with precise laboratory analysis of furan concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A diagram showing a method for quantifying furan concentration according to an embodiment of the present invention.

[0042] Figure 2 It is a graph showing the degree of color development at each concentration of aniline acetate (1:3).

[0043] Figure 3 To express Figure 2 A graph showing the absorbance values ​​per minute for each concentration (1:3).

[0044] Figure 4 It is a graph showing the degree of color development at each concentration of aniline acetate (1:6).

[0045] Figure 5 To express Figure 4 A graph showing the absorbance values ​​per minute for each concentration (1:6).

[0046] Figure 6 It is a graph showing the response value per minute at each wavelength for each concentration of the standard substance.

[0047] Figure 7 It is a graph showing the response values ​​of the standard substances at various concentrations at 520 nm.

[0048] Figure 8 It is a graph showing the response values ​​of the standard substances at various concentrations at 530 nm.

[0049] Fig. 9 The figure shows a color development photograph of 1 mL of a reaction sample and 300 μL of a color development reagent (1:6).

[0050] Fig.10 This is a picture showing a color development photograph of 1 mL of a reaction sample and 1 mL of a color development reagent (1:6).

[0051] Fig.11 It is a graph showing the absorbance value per minute at each concentration of the color developing reagent (1 mL of the extraction solution, 300 μL of the color developing reagent).

[0052] Fig.12 It is a graph showing the absorbance value per minute at each concentration of the color developing reagent (1 mL of the extraction solution, 1 mL of the color developing reagent).

[0053] Fig.13 It is a graph showing the absorbance value per minute at each concentration of the color developing reagent (1.5 mL of the extraction solution, 1 mL of the color developing reagent).

[0054] Fig.14 This is a graph showing the data of the results of the precise analysis and the simple analysis.

[0055] Fig.15 This is a graph showing the comparison between the results of precise analysis and simple analysis.

[0056] Fig.16 This is a graph showing the Pearson correlation analysis results of the precise analysis and the simple analysis results.

[0057] Fig.17 FIG. 1 is a diagram showing a transformer degradation diagnosis method according to an embodiment of the present invention.

[0058] Fig.18 A diagram illustrating the degradation mechanism of cellulose molecules.

[0059] Fig.19 This is a diagram showing furan compounds.

[0060] Fig. 20 This is a graph showing the results of the degree of polymerization analysis of the insulation paper of the grounding transformer.

[0061] Fig.21 To express Fig. 20 A graph showing the relationship between furan concentration and degree of polymerization of insulation paper in actual field samples.

[0062] Fig. 22 This is a graph showing the relationship between the furan concentration and the average degree of polymerization of the insulating paper.

[0063] Fig.23 Figure 2 is a diagram showing the Furan diagnostic criteria for distribution transformers.

[0064] Fig.24 A diagram showing the Furan diagnostic criteria for transmission and transformation transformers.

[0065] Figure 25 to Figure 27 FIG. 1 is a diagram showing a transformer degradation diagnosis device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0066] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, detailed descriptions of known functions or structures that may obscure the subject matter of the present invention in the following description and the accompanying drawings will be omitted. In addition, it should be noted that in all the accompanying drawings, the same structural elements are generally represented by the same symbol.

[0067] The terms or words used in the text and the scope of protection of the invention described below should not be interpreted as limited to the general meaning or dictionary meaning, but should be interpreted as meanings and concepts that are consistent with the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to best explain his invention.

[0068] Therefore, it should be understood that the embodiment described in this article and the structure shown in the drawings are merely one embodiment of the preferred embodiment of the present invention and do not represent all the technical spirit of the present invention. Therefore, various equivalent replacements and modifications can be made as far as this application is concerned.

[0069] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in several different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the accompanying drawings, parts that are not relevant to the description are omitted, and similar parts are marked with similar reference numerals throughout the specification.

[0070] Hereinafter, preferred embodiments of the present invention are described with reference to the accompanying drawings.

[0071] In the transformer degradation diagnosis device of the embodiment of the present invention, furan (furfural) in the insulating oil of the transformer is extracted from the optimal extraction solvent, and after the furan concentration is quantified at the maximum color development wavelength, a diagnostic algorithm based on the correlation between the furan concentration and the degree of polymerization of the insulating paper is applied to each voltage to diagnose the degradation of the transformer based on the furan concentration derived by quantitative analysis.

[0072] As described above, the transformer degradation diagnosis device does not perform qualitative analysis of comparing colors for each concentration level with the naked eye according to the change in the color development degree of furan in the transformer insulating oil, and thus can eliminate uncertainties caused by measurement personnel.

[0073] In addition, the transformer degradation diagnosis device prepares degradation diagnosis standards for the transmission transformer and the distribution transformer according to each voltage based on the furan concentration derived by quantitative analysis so as to accurately diagnose the degradation of the transformer.

[0074] Before describing the transformer degradation diagnosis device, a quantitative analysis method of furan concentration and a transformer degradation diagnosis method used in the transformer degradation diagnosis device are described in detail.

[0075] Figure 1 A diagram showing a method for quantifying furan concentration according to an embodiment of the present invention.

[0076] like Figure 1 As shown, an insulating oil sample is collected from a transformer for judging degradation (step S11), wherein 10 mL of the insulating oil sample is collected.

[0077] Then, the insulating oil sample and the extraction solvent are mixed (step S12). At this time, the insulating oil sample and the extraction solvent are injected into the Econo-Pac Chromatography Column (hereinafter referred to as the "column"), and then mixed evenly by the sample mixer. In addition, the sample mixer automatically shakes the column left and right for 1 minute (about 50 times).

[0078] The column was filled with 500 μL (total volume) of a predetermined resin, and the column cover was opened to inject the extraction solvent and insulating oil sample. In addition, in order to extract furan, 3 mL of 40% methanol was injected as the extraction solvent, and 10 mL of the insulating oil sample was injected.

[0079] Then, the mixed solution of the insulating oil sample and the extraction solvent is left to stand, and the extraction solution is layered at the bottom (step S13). At this time, the column cover is opened and the column is left to stand in a vertical direction.

[0080] Then, the extraction solution from which furan has been extracted is aliquoted (step S14). At this time, the tip of the column is removed, and 1.5 mL of the extraction solution is aliquoted into a vial.

[0081] Then, a color developing reagent is mixed into the extraction solution (ie, the reaction sample) to carry out a reaction (step S15). At this time, the reaction time is 4 minutes.

[0082] The color developing reagent is a reagent in which the ratio of aniline to acetic acid is 1:6. In addition, the color developing reagent is 1 mL and the extraction solution is 1.5 mL. In other words, the ratio of the color developing reagent to the extraction solution is 1:1.5.

[0083] Then, the furan concentration (ie, furan concentration) relative to the color development degree of the extraction solution is quantified by calibration based on the comparison results of the precise analysis and the simple analysis (step S16).

[0084] On the other hand, after the extraction solution reacts with the color developing reagent and turns pink, in order to obtain the optimal wavelength region, the following is determined Figure 1 The ratio of color developing reagent, reaction time and ratio of extraction solution and color developing reagent mentioned in the invention.

[0085] To this end, the present invention is based on Figure 1 The experiment is carried out in the order described above, and the ratio of the color developing reagent, the ratio of the extraction solution to the color developing reagent, and the reaction time are determined by the experimental results. Here, new oil standard substances can be used to replace the insulating oil sample.

[0086] First, in order to Figure 1 The optimal ratio of color developing reagents was obtained, and comparative experiments were carried out with the ratio of aniline to acetic acid being 1:3 and 1:6.

[0087] Figure 2 This is a graph showing the degree of color development at each concentration of aniline acetate (1:3). Figure 3 To express Figure 2 The absorbance value per minute of each concentration (1:3) is plotted. Figure 4 This is a graph showing the degree of color development at each concentration of aniline acetate (1:6). Figure 5 To express Figure 4 A graph showing the absorbance values ​​per minute for each concentration (1:6).

[0088] refer to Figures 2 to 5 ,It can be seen that the chromaticity value is slightly higher at the ,ratio of 1:3.

[0089] However, when the proportion of aniline in the color developing reagent becomes higher, the color development of the extraction solution may be affected by the color of the reagent itself.

[0090] Therefore, in order to increase the proportion of acetic acid and show the best colorimetric reaction, the ratio of the color developing reagent is determined to be 1:6 for aniline and acetic acid. Figure 1 In step S15, a color developing reagent having a ratio of aniline to acetic acid of 1:6 is used.

[0091] Then, a commercial colorimeter can be used to detect that the wavelength region where the extraction solution reacts with the color developing reagent to develop pink is 520 nm and 530 nm.

[0092] In order to Figure 1 The optimal reaction time was derived and a comparative experiment was performed with respect to the colorimeter reaction value of the color development reaction per minute.

[0093] Figure 6 This is a graph showing the response values ​​per minute at each wavelength for each concentration of standard substances. Figure 7 This is a graph showing the response values ​​of each concentration of the standard substance at 520 nm. Figure 8 It is a graph showing the response values ​​of the standard substances at various concentrations at 530 nm.

[0094] refer to Figures 6 to 8 , it can be seen that the response values ​​at 520nm and 530nm do not show significant differences. Therefore, the optimal wavelength region (wavelength range) can be selected from 520nm to 530nm.

[0095] In order to take advantage of the on-site diagnostic kit, it is not advisable to extend the reaction time by more than 10 minutes. Therefore, the results with a reaction time of 7 minutes are reflected, but in Figure 6 The optimal reaction time was determined to be 4 minutes.

[0096] The optimal reaction time is equivalent to the time required for 50 mixings at 90 degrees to the left and right when furan is extracted using an automatic mixer. Preferably, the optimal reaction time is set to prevent the furan from emulsifying due to excessive mixing when furan is extracted.

[0097] Next, in order to Figure 1 The ratio of the extraction solution to the colorimetric reagent was derived so that the addition ratio of the colorimetric reagent was at least 300 μL and at most 1 mL. The amount of the extraction solution for the reaction was 1 ml and 1.5 ml for comparison experiments.

[0098] Fig. 9 This is a picture showing the color development of 1 mL of the reaction sample and 300 μL of the color development reagent (1:6). Fig.10This is a picture showing the color development of 1 mL of the reaction sample and 1 mL of the color development reagent (1:6). Fig.11 This is a graph showing the absorbance value per minute at each concentration of the color developing reagent (1 mL of extraction solution, 300 μL of color developing reagent). Fig.12 This is a graph showing the absorbance value per minute at each concentration of the colorimetric reagent (1 mL of extraction solution, 1 mL of colorimetric reagent). Fig.13 It is a graph showing the absorbance value per minute at each concentration of the color developing reagent (1.5 mL of the extraction solution, 1 mL of the color developing reagent).

[0099] refer to Figures 9 to 13 In the same volume of extraction solution, the more color reagent is mixed, the stronger the pink color is. In addition, it can be seen that when the amount of the extraction solution to be reacted is 1.5 mL at most, the chromaticity value is higher.

[0100] Therefore, the ratio of the extraction solution to the color developing reagent is selected to be 1.5: 1. That is, the extraction solution can be 1.5 mL and the color developing reagent can be 1 mL.

[0101] On the other hand, in order to Figure 1 In step S16, the furan concentration was quantified relative to the degree of color development of the extraction solution, and the correlation between the results of the precise analysis and the results of the simple analysis was confirmed.

[0102] Among them, "precise analysis" refers to the use of high performance liquid chromatography (HPLC) in the laboratory to perform column separation to obtain quantitative values ​​for analyzing furan compounds in transformer insulating oil, and "simple analysis" refers to the color value of actual transformer samples obtained on site. In other words, simple analysis refers to the use of transformer degradation diagnostic equipment to obtain color values.

[0103] Therefore, based on the correlation between the precise analysis result and the simple analysis result (i.e., the comparison result of the precise analysis result and the simple analysis), the simple analysis result can be quantified by correction to a confidence level that matches the precise analysis result. Therefore, the furan concentration confirmed by the transformer degradation diagnosis device can be quantified by correction to a confidence level that matches the precise analysis result.

[0104] Fig.14 This is a graph showing data from a sophisticated analysis and a simple analysis. Fig.15 This is a graph showing the comparison between the results of a precise analysis and a simple analysis.

[0105] refer to Fig.14 By comparing the results of the precise analysis using HPLC, the confidence of the simple analysis results confirmed by the transformer degradation diagnosis device was confirmed.

[0106] Furthermore, in order to eliminate human uncertainty, an automatic mixer was introduced, and it was installed because it takes 4 minutes to mix about 50 times at 90 degrees to the left and right when extracting furan.

[0107] In addition, in order to improve the accuracy of the comparison and verification, 24 samples of distribution-level transformers actually operating on site were collected as comparison objects.

[0108] refer to Fig.15 , the comparison chart of the precise analysis and simple analysis results shows that the simple analysis result value shows a trend of about 17% higher than the precise analysis result value. At this time, there is no significant difference between the values ​​measured according to the overall measurement method, and the trend linearity on the graph also shows good linearity. That is, the graph is presented in the form of a straight line graph of y=1.173*x+2.124.

[0109] In addition, in order to verify the confidence of simple analysis and precise analysis, the correlation between the measured values ​​of each device was analyzed. At this time, the statistical processing used the SPSS (Statistical Package for the Social Science) statistical program. In addition, the correlation between each measurement device was analyzed using the Pearson Correlation Coefficient (Pearson's r).

[0110] The Pearson correlation coefficient (r) is often used to find the correlation between two variables. As one of the most convenient calculations, if two variables x and y are linearly correlated, the calculation is as follows.

[0111]

[0112] in,

[0113]

[0114]

[0115] The range of the Pearson correlation coefficient (r) is -1≤r≤+1.

[0116] At this time, if r=1, it means that there is a complete positive linear correlation between the two variables x and y. If r=0, it means that the two variables x and y are completely independent of each other, that is, there is no linear correlation. If r=-1, it means that there is a complete negative linear correlation between the two variables x and y. The situation of r=0 occurs when xy=0.

[0117] Generally, the Pearson correlation coefficient (r) can be interpreted as shown in Table 1 below.

[0118] Table 1

[0119] The range of Pearson correlation coefficient (r) meaning -1.0≤r≤-0.7 Very strong negative (-) correlation -0.7≤r≤-0.3 Strong negative (-) correlation -0.3≤r≤-0.1 Weak negative (-) correlation -0.1≤r≤0.1 No correlation exists 0.1≤r≤0.3 Weak positive (+) correlation 0.3≤r≤0.7 Strong positive (+) correlation 0.7≤r≤1.0 Very strong positive (+) correlation

[0120] Fig.16 This is a graph showing the Pearson correlation analysis results of the precise analysis and the simple analysis results.

[0121] exist Fig.16 In the correlation analysis results between the precise analysis and simplified analysis results, the Pearson correlation coefficient was 0.978, indicating a very strong positive (+) correlation.

[0122] The significance probability (p-value) is 0.000, which can be interpreted as supporting a high correlation between the precise analysis and the simplified analysis.

[0123] Finally, it can be seen that the simple analysis can have an appropriate confidence level because it has a high correlation with the sophisticated analysis.

[0124] Therefore, the correction result of the precise analysis compared with the simple analysis is reflected in the algorithm for quantifying the furan concentration by the colorimetric measurement relative to the extraction solution in the transformer degradation diagnosis device. Thus, the furan concentration quantified by the simple analysis can be corrected to show a confidence level matching that of the precise analysis.

[0125] In the following, the references mentioned below Fig.17 The transformer degradation diagnosis method is explained in detail.

[0126] Fig.17 : is a diagram showing a transformer degradation diagnosis method according to an embodiment of the present invention, Fig.18 This is a diagram illustrating the mechanism of cellulose molecule degradation. Fig.19 This is a diagram showing furan compounds.

[0127] like Fig.17 As shown, the transformer degradation diagnosis device is used to quantify the furan concentration in the insulating oil of the transformer (step S110). Figure 1 The method for quantifying the furan concentration described above quantifies the furan concentration. Therefore, since the detailed description of the method for quantifying the furan concentration is repeated, its description is omitted.

[0128] Then, the transformer degradation diagnosis device diagnoses the degradation of the transformer according to the furan concentration based on the correlation between the furan concentration and the insulation paper polymerization degree (step S120). That is, the diagnosis algorithm is generated based on the correlation between the furan concentration and the insulation paper polymerization degree.

[0129] Before studying the correlation between furan concentration and degree of polymerization of insulating paper, we refer to Fig.18 as well as Fig.19 , studying the molecular deterioration mechanism of cellulose and furan compounds.

[0130] refer to Fig.18 , the insulating paper used as the main insulator (solid insulating material) of the transformer has a cellulose fiber structure extracted from wood pulp raw material.

[0131] The cellulose fiber structure is composed of cellulose molecular bundles of different lengths, and is formed in the form of molecular bonds based on hydroxyl (OH) and carbon (C). Cellulose itself is a linear polymer of glucose molecular weight, which is bonded by glycosidic molecular bands.

[0132] This cellulose molecular degradation mechanism is complex and depends on the state of the usage environment. However, it is known that when used as an insulator for electrical equipment, the cellulose molecular degradation mechanism is most significant due to thermal factors.

[0133] Due to the deterioration caused by moisture and heat, the glucose bonds of cellulose are broken, and glucose decomposition products remain in the insulation paper. The glucose produced under the action of moisture and acid is decomposed again to produce furfural derivatives. Depending on the conditions, furfural derivatives form Fig.19 The structures of the six furanic compounds are shown.

[0134] Since this furan derivative accurately provides information on the decomposition of insulation paper, this furan derivative series has become one of the diagnostic factors for transformer degradation. In particular, the concentration of furfural, that is, the furan concentration, can be used to indirectly evaluate the decomposition of cellulose.

[0135] Therefore, the use of furan concentration to diagnose transformers is ultimately to prevent failures due to insulation breakdown in advance by determining the degree of decomposition of the transformer insulator, and the correlation analysis between furan concentration and the degree of polymerization of insulating paper shows that since the life of the transformer matches the life of the insulator, the current degradation state of the transformer can be diagnosed.

[0136] Therefore, in order to derive a diagnostic algorithm for diagnosing the deterioration state of the transformer, a correlation analysis between the degree of polymerization of the insulation paper and the furan concentration was actually performed.

[0137] Fig. 20 This is a graph showing the results of the degree of polymerization analysis of the insulation paper of the grounding transformer.

[0138] Fig. 20The results of the analysis of the polymerization degree of the insulation paper of the grounding transformer show the results of the analysis of the polymerization degree of the insulation paper collected on site, expressed by converting the percentage of the polymerization degree of the new paper to each insulation paper. In addition, transformers 4 and 5 could not obtain new paper from the manufacturer, so the average value of the polymerization degree of the new paper at the other three locations was assumed to be the new paper corresponding to the two lines and expressed as a percentage.

[0139] refer to Fig. 20 The higher the furan concentration, the lower the residual polymerization rate of the insulation paper. In particular, the polymerization degree of the insulation paper on the lead side is the lowest. It can be seen that the higher the furan concentration, the more serious the deterioration of the insulation paper.

[0140] Generally, when the degree of polymerization drops to 50% of the initial value, it is judged that the insulation paper has reached its life limit. Fig. 20 It can be judged that the insulation paper of transformers with furan concentrations of 1062ppb and 834ppb respectively have reached their maximum lifespan.

[0141] In addition, when the furan concentration is 354 ppb in the line transformer, the insulating paper at all positions except the upper insulating paper has reached the limit life, and the polymerization degree residual rate of the upper insulating paper is 51%, so it can be judged that it has almost reached the limit.

[0142] In the case of the line transformer with a furan concentration of 107 ppb, the residual rate of the insulating paper on the lead wire side was 56%, and the residual rate of the insulating paper at other locations was 60% or more, which can be judged to be good.

[0143] In addition, in the case of the line transformer having a furan concentration of 87 ppb, the residual polymerization rate of the insulating paper was 70% or more in all cases, and thus it can be judged that the state of the insulating paper was very good.

[0144] Fig.21 To express Fig. 20 The relationship between the furan concentration of the actual field samples and the degree of polymerization of the insulation paper is shown in the figure. Fig. 22 is a graph showing the relationship between furan concentration and average degree of polymerization of insulating paper, Fig.23 A diagram showing the Furan diagnostic criteria for distribution transformers, Fig.24 A diagram showing the Furan diagnostic criteria for transmission and transformation transformers.

[0145] Fig.21 express Fig. 20 Correlation between furan concentration in lead insulation paper (the location with the most serious deterioration) and degree of polymerization of insulation paper of five line transformers.

[0146] refer to Fig.21, it can be seen that the lower the degree of polymerization of the insulation paper, the higher the furan concentration. It can be seen that there is a correlation between the furan concentration and the degree of polymerization of the insulation paper, among which the degree of deterioration of the insulation compared with the furan concentration can be indirectly diagnosed.

[0147] The relationship between the furan concentration of actual field samples and the degree of polymerization of insulating paper Fig. 22 The relationship between the furan concentration in the insulating paper and the average degree of polymerization is roughly the same. Fig. 22 The Chendong model is a prediction curve representing the relationship between furan concentration and degree of polymerization of insulating paper.

[0148] This Chen Dong model is a model that can predict the degree of polymerization of insulating paper from the furan concentration, and the model formula is defined as follows: Equation 1.

[0149] Formula 1: log 10 (2FAL) = 1.51 - 0.0035 × DP

[0150] Where 2FAL refers to the furan concentration in the insulating oil, in mg / L. DP refers to the average degree of polymerization of the insulating paper.

[0151] The deterioration state of the insulating material can be indirectly diagnosed by simulating the relationship between insulating oil and insulating paper according to Equation 1 in the laboratory.

[0152] The transformer degradation diagnosis device according to the embodiment of the present invention is designed to diagnose the current state of the transformer with respect to the furan concentration by using the diagnosis algorithm according to Formula 1.

[0153] refer to Fig.23 ,According to the furan diagnostic standard of the distribution transformer of the diagnostic algorithm, when the furan concentration is 400ppb, the polymerization degree of the insulating paper drops below 50%. Therefore, based on this concentration, four levels of diagnostic results, including normal, concern, attention, and abnormal, can be provided.

[0154] refer to Fig.24 According to the diagnostic algorithm, the furan diagnostic standard for transmission and transformation transformers (transformers above 154kV) is based on a furan concentration of 350ppb, which is higher than the concentration standard for distribution transformers. It can provide three levels of diagnostic results: normal, attention required, and abnormal.

[0155] Figure 25 to Figure 27 FIG. 1 is a diagram showing a transformer degradation diagnosis device according to an embodiment of the present invention.

[0156] like Figure 25 to Figure 27 As shown, the transformer degradation diagnosis device 200 according to the embodiment of the present invention is a portable furan diagnosis device that quantifies furan compounds decomposed from transformer insulation through optimal reaction time, wavelength region and color developing reagent, and displays the diagnosis results according to each voltage.

[0157] The transformer degradation diagnosis device 200 includes a component 210 , a sample mixer 220 , and a colorimeter 230 .

[0158] Part 210 includes an extraction solvent container 212a having an extraction solvent 212 and a color development reagent container 211a having a color development reagent 211. The extraction solvent container 212a may be an econo-pack chromatographic column, and the color development reagent container 211a may be a vial. The extraction solvent 212 is stored in the container in consideration of the amount and optimal ratio of the reaction sample. In addition, the color development reagent 211 derives the optimal reaction conditions and sets the ratio of aniline to acetic acid to 1:6.

[0159] In addition, the sample mixer 220 continuously shakes the extraction solvent container 212a 90 degrees to mix the mixture. At this time, the mixed solution of the extraction solvent and the insulating oil sample is stationary at the bottom of the extraction solvent container 212a, so that the extraction solution is separated into layers.

[0160] In order to extract furan from the insulating oil sample, if the mixing is too vigorous, the furan is emulsified, so mixing is performed at an appropriate speed using the sample mixer 220. Since the sample mixing process has a large human uncertainty factor depending on the analyst, the optimal reaction time of the sample mixer 220 is set, and furan is extracted from the insulating oil sample in an optimal state.

[0161] In addition, the colorimeter 230 includes a display 232 , a colorimetric filter 231 , a processor 233 , and a memory 234 .

[0162] First, the display 232 can display the Figure 1 The furan concentration was confirmed by the quantitative method described in Fig.17 The transformer degradation diagnosis result confirmed by the transformer degradation diagnosis method of the present invention. For example, the display 232 can be a touch screen with input function and display function. At this time, the display 232 displays the degradation diagnosis result of the distribution transformer or the transmission and distribution transformer according to each voltage classification.

[0163] In addition, the colorimetric filter 231 enables measurement of the color for quantifying the furan concentration in the optimal wavelength region (520 nm, 530 nm) after the extraction solution reacts with the color developing reagent 211 and turns pink.

[0164] In addition, the processor 233 may also be referred to as a controller, a microcontroller, a microprocessor, a microcomputer, etc. In addition, the processor 203 may be implemented by hardware, firmware, software, or a combination thereof.

[0165] In addition, the memory 234 may be a storage device, or may be a collective term for a plurality of storage elements, and is configured to store executable program codes or parameters, data.

[0166] Such memory 234 may include random access memory (RAM), or may include non-volatile memory (NVRAM) such as a disk storage device or flash memory.

[0167] When the computer readable instructions stored in the memory 234 are executed, the processor 233 executes Figure 1 The quantification method of furan concentration described in Fig.17 That is, the transformer degradation diagnosis device 200 performs Figure 1 The quantification method of furan concentration described in Fig.17 Transformer degradation diagnosis method described in .

[0168] In this way, the transformer degradation diagnosis device 200 can accurately quantify the furan concentration and diagnose the insulation degradation state of the transformer.

[0169] As described above, in order to improve the accuracy of furan concentration quantification, the extraction solvent, the mixing ratio of the color developing reagent, and the optimal wavelength are set, and a sample mixer is used to remove human uncertainties. A calibration algorithm and a transformer degradation diagnosis algorithm are included to correct the accuracy of simple analysis and precise analysis.

[0170] In addition, the transformer degradation diagnosis device 200 applies a diagnosis algorithm based on the furan concentration in the insulating oil of the distribution transformer and the transmission and distribution transformer, respectively, so that the "normal", "caution" and "abnormal" judgment criteria can be confirmed, and the user can immediately diagnose the degradation state of the transformer.

[0171] According to the method of some embodiments, the form of executable program instructions can be realized by various computer means and recorded in a computer-readable medium. The computer-readable medium may contain program instructions, data files, data structures, etc., alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the present invention, or may be known and usable by technicians in the field of computer software. Examples of computer-readable recording media include magnetic media (magnetic media), such as magnetic media such as hard disks, floppy disks, and tapes; optical recording media, such as CDROMs and DVDs; magneto-optical media (magneto-optical media), such as floppy disks (floptical disks); and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include not only machine language codes generated by compilers, for example, but also high-level language codes that can be executed by computers using interpreters, etc.

[0172] Although the above description focuses on the novel features of the present invention as applied to various embodiments, it will be appreciated by those skilled in the art that various deletions, substitutions and changes may be made to the form and details of the above-mentioned apparatus and method without departing from the scope of the present invention. Therefore, the scope of the present invention is defined by the appended invention claims rather than by the above description. All modifications within the equivalent scope of the invention claims are included within the scope of the present invention.

Claims

1. A transformer degradation diagnosis method, wherein: include: Steps for quantifying the furan concentration of an insulating oil sample collected from a transformer; as well as A step of diagnosing a degradation state of the transformer using the quantitative furan concentration based on a correlation between the furan concentration and the degree of polymerization of the insulation paper; The step of quantifying the furan concentration of the insulating oil sample collected through the transformer comprises: The steps of mixing a color developing reagent in which aniline and acetic acid are mixed in a specified ratio into an extraction solution for extracting furan from an insulating oil sample to react, and measuring the color development degree of the extraction solution; and a step of quantifying the furan concentration by correcting the color development degree of the extraction solution based on the correlation between precise analysis and simple analysis, The precision analysis is to analyze the furan compounds in the transformer insulating oil using high performance liquid chromatography performed in the laboratory and to obtain quantitative values ​​through column separation. The simple analysis is to obtain the chromaticity value of the actual transformer sample on site. The insulating oil sample and the extraction solvent are mixed 50 times at 90 degrees to the left and right by the sample mixer for a reaction time of 4 minutes. The color development degree of the extraction solution is measured in the wavelength region of 520 nm and 530 nm, Using the furan concentration derived from the quantitative analysis, the transformer degradation diagnosis criteria are prepared for each voltage; In the step of diagnosing the deterioration state of the transformer, after quantifying the furan concentration, the deterioration state of the transformer for the furan concentration is diagnosed according to each voltage by a diagnostic algorithm based on a Chendong model formula, wherein the Chendong model formula represents the correlation between the furan concentration and the degree of polymerization of the insulating paper; The Chen Dong model is a model for predicting the degree of polymerization of insulating paper from the furan concentration. The Chen Dong model formula is defined as follows: log 10 (2FAL)=1.51-0.0034×DP Wherein, the 2FAL refers to the furan concentration in the insulating oil, in mg / L; and the DP refers to the average degree of polymerization of the insulating paper.

2. The transformer degradation diagnosis method according to claim 1, wherein: The extraction solution is a layer formed at the bottom of the insulating oil sample after the insulating oil sample is mixed with the extraction solvent and the sample is allowed to stand in a vertical direction.

3. The transformer degradation diagnosis method according to claim 1, wherein: In the color developing reagent, the ratio of aniline to acetic acid is 1:

6.

4. The transformer degradation diagnosis method according to claim 3, wherein: The ratio of the extraction solution to the color developing reagent is 1:1.5, The reaction time of the extraction solution and the color developing reagent is 4 minutes.

5. The transformer degradation diagnosis method according to claim 1, wherein: In the correlation between the precise analysis and the simple analysis, the confidence is verified by Pearson correlation analysis using the Pearson correlation coefficient (r) calculated by the following formula, Mode: in, The two variables x and y are linearly related.

6. The transformer degradation diagnosis method according to claim 1, wherein: In the diagnosis step, step-by-step diagnosis results are provided based on the furan concentration at which the degree of polymerization of the insulation paper drops below 50%.

7. The transformer degradation diagnosis method according to claim 6, wherein: The diagnosis results can be provided by the distribution transformer and the transmission transformer respectively.

8. A transformer degradation diagnosis device, in, include: at least one processor; and a memory for storing computer readable instructions, When the instruction is executed by the at least one processor, the transformer degradation diagnosis device is enabled to: Quantify the furan concentration in insulating oil samples collected from transformers, Based on the correlation between furan concentration and the degree of polymerization of insulating paper, the quantitative furan concentration is used to diagnose the deterioration state of the transformer, When the instruction is executed by the at least one processor, the transformer degradation diagnosis device is enabled to: When quantifying the furan concentration, a color developing reagent in which aniline and acetic acid are mixed in a prescribed ratio is mixed in an extraction solution for extracting furan from an insulating oil sample to react, and the degree of color development of the extraction solution is measured; quantifying the furan concentration by correcting the color development degree of the extraction solution based on the correlation between precise analysis and simple analysis; The precision analysis is to analyze the furan compounds in the transformer insulating oil using high performance liquid chromatography performed in the laboratory and to obtain quantitative values ​​through column separation. The simple analysis is to obtain the chromaticity value of the actual transformer sample on site. The insulating oil sample and the extraction solvent are mixed 50 times at 90 degrees to the left and right by the sample mixer for a reaction time of 4 minutes. The color development degree of the extraction solution is measured in the wavelength region of 520 nm and 530 nm, Using the furan concentration derived from the quantitative analysis, the transformer degradation diagnosis criteria are prepared for each voltage; In the diagnosing the deterioration state of the transformer, after the furan concentration is quantified, the deterioration state of the transformer for the furan concentration is diagnosed according to each voltage by a diagnostic algorithm based on a Chendong model formula, wherein the Chendong model formula represents the correlation between the furan concentration and the degree of polymerization of the insulating paper; The Chen Dong model is a model for predicting the degree of polymerization of insulating paper from the furan concentration. The Chen Dong model formula is defined as follows: log 10 (2FAL)=1.51-0.0034×DP Wherein, the 2FAL refers to the furan concentration in the insulating oil, in mg / L; and the DP refers to the average degree of polymerization of the insulating paper.

9. The transformer degradation diagnosis device according to claim 8, wherein: The extraction solution is a layer formed at the bottom of the insulating oil sample after the insulating oil sample is mixed with the extraction solvent and the sample is allowed to stand in a vertical direction.

10. The transformer degradation diagnosis device according to claim 9, wherein: Also included is a display for displaying the quantified furan concentration and a step-by-step diagnostic result based on the quantified furan concentration.

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