CN111579948A - Method for analyzing fault of mixed insulating oil transformer based on dissolved gas in oil - Google Patents
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Abstract
The invention relates to a method for analyzing faults of a mixed insulating oil transformer based on dissolved gas in oil, and belongs to the technical field of automation. The method comprises the following steps: s1: carrying out a test of gas production characteristics under thermal fault and discharge fault; s2: analyzing the characteristics of dissolved gas in oil under thermal fault and discharge fault; s3: researching characteristic gas under the ternary mixed oilpaper insulation overheating fault and the discharge fault; s4: and establishing a triangular graphic diagnosis model of dissolved gas in oil of the overheat fault and the discharge fault of the hybrid insulating oil transformer. The method divides the typical faults of the mixed insulating oil transformer by the content and the proportion of the dissolved gas in the oil, fills the blank of the fault diagnosis method of the mixed insulating oil transformer, and provides technical support for popularization, application, operation and maintenance of the mixed insulating oil transformer.
Description
Technical Field
The invention belongs to the technical field of automation, and relates to a method for analyzing faults of a mixed insulating oil transformer based on dissolved gas in oil.
Background
In 2006, researches by the French Ashi enamel group C.Perrier and the French Lyon university A.Beroual et al indicate that the mixed oil consisting of 80 vol.% of mineral oil and 20 vol.% of synthetic ester can effectively improve the power frequency breakdown voltage and the aging resistance of the oil product. In 2009-2012, Chongqing university developed a mixed insulating oil with a formula of 20 vol.% olive oil and 80 vol.% mineral oil, and the key parameters of the mixed insulating oil meet the requirements of national standard GB2536-90 and can effectively delay the thermal aging of oil paper insulation. 2012-2014, a Chongqing university team and Chongqing electric power company collaborate to develop an application research of a scientific and technological project of improving the performance of insulating oil to prolong the service life of a distribution transformer, two 10kV/200kVA mixed insulating oil distribution transformers are researched and successfully developed internationally for the first time, and the grid-connected operation is realized in the district of the northriver power supply office of the electric power company in Chongqing city of the state grid. In 2019, a novel ternary mixed insulating oil is developed at home and abroad by Chongqing university, the performance parameters of the ternary mixed insulating oil meet the requirements of the standard GB 2536-. Compared with mineral insulating oil, the novel ternary mixed insulating oil has higher power frequency breakdown voltage, better fireproof performance and more excellent thermal performance, and can obviously delay the aging of insulating paper/paperboard cellulose. At present, a mixed insulating oil transformer adopting the novel ternary mixed insulating oil is operated in a power supply district of Yongchuan Chongqing by hanging a network.
Thermal failure and insulation discharge failure are the main factors causing the shutdown of the transformer, and the thermal failure is mainly divided into three levels, i.e.<300℃、300℃<t<700°、>700 ℃; the discharge fault mainly comprises three types of partial discharge, low-energy discharge (small oil gap surface flashover, power frequency breakdown, lightning impulse breakdown and the like), and high-energy discharge (long oil gap discharge breakdown and the like). Thermal and insulation discharge failures can both cause the decomposition of the oiled paper insulation material, producing H2、CO2Iso-non-hydrocarbon gas, and CH4、C2H2And the like, and therefore, the type of the transformer discharge fault can be judged according to the difference of the contents of various characteristic gases dissolved in the oil.
The fault diagnosis method based on analysis of dissolved gas in oil has the advantage of no need of stopping the transformer, and is widely applied to fault diagnosis of the oil-immersed transformer. At present, IEEE Std C57.104 published abroadTM2008 IEEE Guide for the Interpretation of gas Generated in Oil-amplified transformations and IEEE StdC57.155TM-2014 Standard IEEE Guide for Interpretation of gas Generated in Natural and Synthetic Instrument provides theoretical and methodological guidance for fault diagnosis of mineral oil transformers and natural Ester/Synthetic Ester transformers based on analysis of dissolved gas in oil. DLT722-2014 'guide rules for analyzing and judging dissolved gas in transformer oil' proposed for mineral oil transformers in China has already been mature in application, but specific guide rules and standards for fault diagnosis of natural ester/synthetic ester transformers based on analysis of dissolved gas in oil are still lacking.
Compared with mineral oil and natural ester, the mixed insulating oil is formed by mixing a plurality of single oil products, and the insulating failure gas production characteristic of the mixed insulating oil is different from that of the single oil product. At present, no related analysis method for fault diagnosis of the mixed insulating oil transformer is available at home and abroad. With the popularization and application of the mixed insulating oil transformer, in view of the advantage of transformer fault diagnosis, a method for analyzing and identifying the type of the insulating discharge fault of the mixed insulating oil transformer based on the dissolved gas in the oil is needed, firstly, the insulating discharge defect of the mixed insulating oil transformer is discovered as soon as possible by the method, and the safe operation of the mixed insulating oil transformer is guaranteed; and secondly, aiming at the type of the insulation discharge fault, a technical support is provided for operation and maintenance of the insulation discharge fault.
Disclosure of Invention
In view of the above, the present invention provides a method for analyzing a fault of a hybrid insulating oil transformer based on a gas dissolved in oil.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for analyzing the fault of a hybrid insulating oil transformer based on dissolved gas in oil comprises the following steps:
s1: carrying out a test of gas production characteristics under thermal fault and discharge fault;
s2: analyzing the characteristics of dissolved gas in oil under thermal fault and discharge fault;
s3: researching characteristic gas under the ternary mixed oilpaper insulation overheating fault and the discharge fault;
s4: and establishing a triangular graphic diagnosis model of dissolved gas in oil of the overheat fault and the discharge fault of the hybrid insulating oil transformer.
Optionally, the S1 specifically includes:
normal heat aging
In a normal thermal aging gas production test of ternary mixed insulating paper, the thermal aging temperature is 120 ℃, the moisture content of the dried ternary mixed insulating oil is about 14ppm, and the moisture content of the insulating paper is less than 1%; the 12 wide-mouth bottles with 500mL are divided into 2 groups, namely a pure oil thermal aging group and an oil paper thermal aging group; 500mL of ternary mixed insulating oil is poured into the pure oil thermal aging group, insulating paper is added into the oil paper thermal aging group after the insulating oil is removed, and the oil paper mass ratio is controlled to be 20: 1; placing all the jars under the condition of 60 ℃/50Pa for 24h to finish the oil immersion process, and finally sealing all the jars in a nitrogen environment;
aging the samples immersed in the oil at 120 ℃, wherein the sampling interval is 10 days, and testing the components and the content of the dissolved gas in the oil sampled each time until 6 samples are taken;
② overheating fault
According to different temperatures of the hot spots, transformer overheating faults are divided into low-temperature overheating, namely, the temperature is less than 300 ℃, medium-temperature overheating, namely 300-700 ℃, and high-temperature overheating, namely, the temperature is more than or equal to 700 ℃; the method is characterized in that the method adopts a tubular muffle furnace heating mode to simulate overheating at different temperatures, and comprises the tubular muffle furnace and a special heating pipe; the sample amount added into the sample chamber is controlled in each test, the adding amount of insulating oil is 30mL, the insulating oil in the oil-impregnated paper sample is 30mL, the mass of the insulating paper is 1.3g, and the oil-paper ratio is kept to be about 20: 1; during the test, the tubular muffle furnace is used for heating to a specific temperature, the gas generated by overheating of the sample is led out to a closed container filled with 500mL of insulating oil through the sample tube, and the gas generated by overheating can be dissolved in the degassed insulating oil; when the overheating test time is up, taking out the heating pipe and standing for 5 minutes to enable the generated gas to be uniformly dissolved in 500mL of insulating oil; finally, taking an insulating oil sample to test the content of dissolved gas in the insulating oil sample;
(iii) discharge failure
1) Partial discharge fault
Making a corona discharge and air gap defect model according to a CIGRE Method II electrode system structure, and simulating corona discharge of a metal tip in a transformer by adopting a needle-plate electrode, wherein the distance between the needle plate electrodes is 10 mm; the air gap defect is formed by adopting a ball electrode and tightly bonding oil-immersed paperboards through 704 high-voltage silicon rubber, and the inner diameter D of a pore is 3.5 cm; the partial discharge fault gas production test adopts a constant voltage method, 1.2 times of initial discharge voltage is selected as test voltage, and the test voltage of corona discharge and air gap discharge is respectively 24kV and 7.5 kV; after the external applied voltage is slowly increased to the test voltage, respectively extracting insulating oil samples when partial discharge is carried out for 6 hours, 12 hours and 24 hours, and measuring the components and the content of dissolved gas in each sample oil;
2) breakdown fault at power frequency
The industrial frequency breakdown fault gas production test of the ternary mixed insulating oil uses a standard oil cup specified by national standard, the electrode adopts a plate electrode, and the oil gap width between the electrodes is 2.5 mm; standing for 3 minutes before the first test of the insulating oil; after each time of breakdown of the insulating oil, stirring the insulating oil for 1 minute and standing for 3 minutes; uniformly boosting at a speed of 2kV/s until the insulating oil breaks down, respectively breaking down for 10 times, 20 times, 40 times and 60 times, extracting the broken-down insulating oil sample, and measuring the components and the content of each dissolved gas;
in a power frequency breakdown fault gas production test of the oil-immersed insulating paperboard, a testing electrode selects a column electrode with equal diameter; the thickness of the paperboard is 0.5mm, and the boosting rate is 1 kV/s; after 20 times, 40 times and 60 times of breakdown of the insulating oil-immersed paperboard, extracting an insulating oil sample and measuring components and contents of various dissolved gases;
3) flashover fault along surface
Simulating the oil-paper surface flashover fault under the condition of an internal electrode uneven electric field and a slightly uneven electric field of the transformer by using a copper needle-plate electrode and a finger-finger electrode, wherein the radius of curvature of a needle point is 0.25mm, and the radius of the tip end of the finger electrode is 2.5 mm; the boosting rate of the alternating voltage is 3kV/s, and the distance between the high-voltage electrode and the low-voltage electrode is 10 mm; after 3, 5, 10, 15 and 20 surface flashover faults occur, extracting an insulating oil sample and measuring the components and the content of each dissolved gas;
4) breakdown fault of lightning impulse
The lightning impulse test system consists of an impulse voltage generation system, a signal measurement system and an experimental electrode; the external applied voltage of a lightning impulse breakdown fault gas production test is standard lightning impulse voltage waves, namely 1.2 +/-30% mu s and 50 +/-20% mu s, and a pin-plate electrode is adopted to simulate an electrode uneven electric field, wherein the curvature radius of the tip of a tungsten pin electrode is 50 mu m, and the diameter of a copper plate electrode is 50 mm; in an insulating oil lightning impulse breakdown fault gas production test, the length of a pin-plate electrode oil gap is 10mm, and test voltage amplitudes under positive and negative polarities are respectively set to be 50kV and 55kV according to the lightning impulse breakdown voltage of the insulating oil; respectively performing breakdown for 20 times, 40 times and 60 times under the action of positive and negative polarity lightning impulse voltage, then extracting an insulating oil sample and measuring components and contents of each dissolved gas;
in a lightning impulse breakdown fault gas production test of the oil-immersed insulating paper board, the thickness of the paper board is 1mm, and the amplitude of lightning impulse voltage under positive and negative polarities is 120 kV; and (3) respectively puncturing the oil-immersed insulating paper board for 6 times, 12 times and 18 times under the action of positive and negative polarity lightning impulse voltages, then extracting an insulating oil sample and measuring components and contents of various dissolved gases.
Optionally, the S2 specifically includes:
normal heat aging
CO dissolved in ternary mixed insulating oil in 120 ℃ thermal aging process2Highest content, next to H2、C2H6And CO, the peroxidation of unsaturated fatty acids of vegetable oils at low temperature and overheating is C2H6The reason for the higher yield; the gas generated by the insulation aging of the ternary mixed oilpaper still contains CO2Mainly of CO, and2over 85 percent of the total gas, and CO is aged than pure oil2The percentage of total gas is significantly higher;
② overheating fault
When the medium and low temperature is overheated, the gas generated by the ternary insulating oil is CO2High temperature overheating fault H2And a significant increase in hydrocarbon gas content; the gas generated by the oiled paper insulation at different overheating temperatures is CO2And CO produced by overheating of the oiled paper as compared to overheating of pure oil at the same temperature2The amount is obviously increased, and CO is generated for the overheating of pure oil23-5 times of the amount of the pure oil, wherein the CO gas production is 2-3 times of the pure oil overheating; the total amount of gas generated by the ternary mixed oilpaper insulation overheating is obviously more than that generated by the pure oil overheating, the extra gas is carbon oxide, even if the hydrocarbon gas generation amount is greatly increased when the ternary mixed oilpaper insulation overheating is performed at high temperature, the total amount of the carbon oxide still accounts for more than 70% of the total gas, and the percentage of the carbon oxide is far higher than that of the pure oil overheating;
(iii) discharge failure
1) Partial discharge fault
Dissolved CO in oil under partial discharge failure2And little change in CO content; h is generated under two partial discharge faults of ternary mixed insulating oil2Similar to the gas quantity and proportion of hydrocarbon gas, the characteristic gas in partial discharge fault is H2(ii) a Except for H2External, partial dischargeThe two gases produced at the most are CH4And C2H2And the content is less than H21/3 of (1);
2) breakdown fault at power frequency
The gas generated in the breakdown process of the ternary mixed insulating oil is C2H2、H2And C2H4Increasing with increasing number of breakdowns, especially C2H2The content of the gas is increased most obviously in the breakdown process and is the characteristic gas of breakdown failure; compared with the characteristic gas C2H2，H2Is less than C2H2Half of the production; the gas generated after the oil-immersed insulating paperboard is punctured for many times is greatly different from that generated after the oil-immersed insulating paperboard is punctured for many times; the most obvious different phenomenon is H generated after the breakdown of the oil-immersed paperboard2The amount is obviously increased compared with the breakdown of pure oil, and the production amount is similar to or slightly higher than C2H2The gas yield of (2) is one of characteristic gases of the oil-immersed paperboard under breakdown failure; secondly, when the oil-immersed insulating paperboard breaks down, C2H2The content of the characteristic gas which is generated in a large amount after multiple breakdowns is obviously increased along with the increase of the number of breakdowns; compared with the breakdown fault of pure oil, C generated after the oil-immersed paperboard is broken down for the same times2H2The amount is larger;
3) flashover fault along surface
H dissolved in oil with increasing flashover times along the surface2And a significant increase in hydrocarbon gas content, in which C is dissolved in the oil2H2And H2The content changes remarkably; compared with 3 flashovers, the oil-paper has 20 surface flashovers of CO in the oil2The content ratio is obviously reduced, and H2And the content of each hydrocarbon gas is obviously increased, wherein C2H2The content ratio exceeds 40 percent; the content and the proportion of C2H2 change obviously before and after the surface flashover fault, and the carbon dioxide is used as the characteristic gas of the surface flashover fault of the ternary mixed insulating oil-paper composite system;
4) breakdown fault of lightning impulse
With the increase of the breakdown times of lightning impulse, the concentration of each characteristic gas in the oil is equalNow in an increasing trend, H in non-hydrocarbon gases2Content and C in hydrocarbon gas2H2The content is obviously improved; compared with the trace proportion in the new oil, the positive and negative polarities are punctured for 60 times and then H2And C2H2The sum of the content ratios is up to 72.84% and 66.71%, and the sum is used as the characteristic gas of the lightning impulse breakdown fault of the ternary mixed insulating oil;
compared with insulating oil, the H dissolved in the oil after the lightning impulse breakdown of the insulating oil-immersed paperboard2And higher content of hydrocarbon gases, in which the oil contains dissolved CH4、C2H4And C2H6The content ratio is obviously improved; h2And C2H2The content of the gas is the highest in the oil, and the difference between the gas and the oil is smaller than the difference of the pure oil after lightning impulse breakdown.
Optionally, the S3 specifically includes:
the characteristic gas diagnosis method is a diagnosis method for distinguishing transformer faults according to the components and the contents of main and secondary gases; and (4) qualitatively reflecting the fault type of the equipment according to the gas production characteristics under the ternary mixed oil paper insulation overheating fault and the discharge fault.
Optionally, the S4 specifically includes:
the gas with the largest amount of breakdown failure generation is C2H2And H2The gas generated by partial discharge is H2，C2H2The production amount is less; according to C2H2And H2Distinguishing the relation among the contents, namely distinguishing an oil breakdown fault, an oil-impregnated paper breakdown fault and a partial discharge fault; c is to be2H2And H2Characteristic gases as a graphic diagnostic;
CO removal of gas generated under overheating fault and ternary mixed oilpaper insulation overheating fault2And CO is other than C2H6、C2H4(ii) a Certain amount of C is also generated due to peroxidation of unsaturated fatty acid during normal thermal aging of the ternary mixed insulating oil2H6Will interfere with the determination of the result, and C2H4Difficult to form at normal aging temperatures; bonding ofUnder electrical fault H2The differentiating action of (1) selecting from C2H4And H2Two gases to distinguish different overheating faults;
to sum up, select C2H2、H2And C2H4The three gases are used as characteristic gases of a triangle graphic diagnostic method and are used for fault diagnosis of the ternary mixed insulating oil; are respectively provided with C2H2、H2And C2H4As X, Y and X axis, the coordinate calculation method in the triangular coordinate system corresponding to each gas sample is shown in formulas (1) to (3);
wherein X, Y and Z are respectively C2H2、H2、C2H4Coordinates of three characteristic gases in a triangular coordinate system, C (C)2H2)、c(H2)、c(C2H4) The content of the three gases is respectively, and the unit is mu L/L; and substituting the test results under the ternary mixed oilpaper insulation overheating fault and the electrical fault into the formulas (1) to (3) to obtain coordinate values, and listing data points in a triangle.
The invention has the beneficial effects that: the invention divides the typical overheating fault and the discharging fault of the transformer by the characteristic gas components and contents. Firstly, aiming at the thermal fault of the transformer, the overheating faults of the mixed insulating oil paper at different temperatures are simulated, and the content of dissolved gas in oil of each insulating oil sample after the thermal fault is tested. And secondly, simulating a partial discharge fault, a surface flashover fault, a power frequency breakdown fault and an impact breakdown fault of the mixed insulating liquid oilpaper aiming at the typical discharge fault of the transformer, and testing the content of dissolved gas in oil of each insulating oil sample after the discharge fault. Finally, according to the characteristics of dissolved gas in oil under various overheating faults and discharge faults of the mixed insulating oil paper, obtaining main characteristic gas and secondary characteristic gas under various typical faults; based on the proportion of each characteristic gas in oil under typical faults, a diagnosis method for the faults of the mixed insulating oil transformer is provided, and the accuracy of the diagnosis method is verified. The method divides the typical faults of the mixed insulating oil transformer by the content and the proportion of the dissolved gas in the oil, fills the blank of the fault diagnosis method of the mixed insulating oil transformer, and provides technical support for popularization, application, operation and maintenance of the mixed insulating oil transformer.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a simulated superheater structure;
FIG. 3 is a typical partial discharge defect model; FIG. 3(a) is a corona discharge model; FIG. 3(b) is an air gap discharge model;
FIG. 4 is a power frequency breakdown fault electrode structure; FIG. 4(a) is a power frequency breakdown model of insulating oil; FIG. 4(b) is a power frequency breakdown model of the oil-immersed paperboard;
FIG. 5 is a planar flashover fault electrode configuration;
FIG. 6 is a lightning impulse breakdown fault testing system;
FIG. 7 is the content of each dissolved gas in oil under normal thermal aging of ternary mixed oiled paper insulation; FIG. 7(a) is a ternary mixed insulating oil; FIG. 7(b) ternary hybrid oilpaper insulation;
FIG. 8 is the content of each dissolved gas in oil under the fault of overheating of ternary mixed oilpaper insulation; FIG. 8(a) is a ternary mixed insulating oil; FIG. 8(b) is a ternary mixed oilpaper insulation;
FIG. 9 shows the content of each dissolved gas in oil under partial discharge failure of ternary mixed oilpaper insulation; FIG. 9(a) is a corona discharge; FIG. 9(b) is an air gap discharge;
FIG. 10 shows the content of each dissolved gas in oil under the power frequency breakdown fault of the ternary mixed oilpaper insulation; FIG. 10(a) is a ternary mixed insulating oil; FIG. 10(b) is a ternary mixed oilpaper insulation;
FIG. 11 shows the content of each dissolved gas in oil under the flashover fault along the surface of the ternary mixed oil paper insulation; FIG. 11(a) is a pin-plate electrode; FIG. 11(b) shows finger-finger electrodes;
FIG. 12 is the content of each dissolved gas in oil under breakdown failure of lightning impulse insulation of ternary mixed oil paper; FIG. 12(a) is a ternary mixed insulating oil; fig. 12(b) is a ternary hybrid insulating oil-impregnated paper board;
FIG. 13 is a triangular graphical representation of the dissolved gas in oil diagnostic model for a hybrid insulating oil transformer overheating fault and discharge fault;
fig. 14 is a verification of the ternary mixed insulating oil graphical diagnostic method.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
FIG. 1 is a flow chart of the present invention; FIG. 2 is a simulated superheater structure; FIG. 3 is a typical partial discharge defect model; FIG. 3(a) is a corona discharge model; FIG. 3(b) is an air gap discharge model; FIG. 4 is a power frequency breakdown fault electrode structure; FIG. 4(a) is a power frequency breakdown model of insulating oil; FIG. 4(b) is a power frequency breakdown model of the oil-immersed paperboard; FIG. 5 is a planar flashover fault electrode configuration; FIG. 6 is a lightning impulse breakdown fault testing system; FIG. 7 is the content of each dissolved gas in oil under normal thermal aging of ternary mixed oiled paper insulation; FIG. 7(a) is a ternary mixed insulating oil; FIG. 7(b) ternary hybrid oilpaper insulation; FIG. 8 is the content of each dissolved gas in oil under the fault of overheating of ternary mixed oilpaper insulation; FIG. 8(a) is a ternary mixed insulating oil; FIG. 8(b) is a ternary mixed oilpaper insulation; FIG. 9 shows the content of each dissolved gas in oil under partial discharge failure of ternary mixed oilpaper insulation; FIG. 9(a) is a corona discharge; FIG. 9(b) is an air gap discharge; FIG. 10 shows the content of each dissolved gas in oil under the power frequency breakdown fault of the ternary mixed oilpaper insulation; FIG. 10(a) is a ternary mixed insulating oil; FIG. 10(b) is a ternary mixed oilpaper insulation; FIG. 11 shows the content of each dissolved gas in oil under the flashover fault along the surface of the ternary mixed oil paper insulation; FIG. 11(a) is a pin-plate electrode; FIG. 11(b) shows finger-finger electrodes; FIG. 12 is the content of each dissolved gas in oil under breakdown failure of lightning impulse insulation of ternary mixed oil paper; FIG. 12(a) is a ternary mixed insulating oil; fig. 12(b) is a ternary hybrid insulating oil-impregnated paper board; FIG. 13 is a triangular graphical representation of the dissolved gas in oil diagnostic model for a hybrid insulating oil transformer overheating fault and discharge fault; fig. 14 is a verification of the ternary mixed insulating oil graphical diagnostic method.
The invention diagnoses and analyzes the ternary mixed oil paper insulation fault type based on the characteristic of dissolved gas in oil, and the patent implementation flow chart is shown in figure 1.
1 test method of gas production characteristics under thermal fault and discharge fault
Normal heat aging
In a normal thermal aging gas production test of the ternary mixed insulating paper, the thermal aging temperature is 120 ℃, the moisture content of the dried ternary mixed insulating oil is about 14ppm, and the moisture content of the insulating paper is less than 1%. 12 jars of 500mL are divided into 2 groups, pure oil heat aging group and oil paper heat aging group respectively. 500mL of ternary mixed insulating oil is poured into the pure oil thermal aging group, insulating paper is added into the oil paper thermal aging group after the insulating oil is removed, and the mass ratio of the oil paper is controlled to be 20: 1. All jars were placed at 60 ℃/50Pa for 24h to complete the oil immersion process, and finally all jars were sealed under nitrogen.
Aging the oil-immersed samples at 120 ℃ at sampling intervals of 10 days until 6 samples are taken, and testing the components and the content of the dissolved gas in the oil sampled each time.
② overheating fault
According to different temperatures of the hot spot, the overheat faults of the transformer can be divided into low-temperature overheat (less than 300 ℃), medium-temperature overheat (300-700 ℃) and high-temperature overheat (more than or equal to 700 ℃). The tube muffle furnace heating was used herein to simulate superheating at different temperatures, as shown in fig. 2.
The device main body consists of a tubular muffle furnace and a special heating pipe. The sample amount added into the sample chamber is controlled in each test, the adding amount of the insulating oil is 30mL, the insulating oil in the oil-impregnated paper sample is also 30mL, the mass of the insulating paper is 1.3g, and the oil-paper ratio is kept to be about 20: 1. In the test, the temperature is raised to a specific temperature by using a tubular muffle furnace, the gas generated by overheating of the sample is led out into a closed container filled with 500mL of insulating oil (depending on the oil for the test) through a sample tube, and the gas generated by overheating can be dissolved in the degassed insulating oil. The test times were different, as shown in table 1, given the different rates of superheated gassing of the samples at the different temperatures. When the overheating test time is up, the heating pipe is taken out and is kept stand for 5 minutes, so that the generated gas can be uniformly dissolved in 500mL of insulating oil. Finally, a sample of the insulating oil was taken to test the dissolved gas content therein.
TABLE 1 test times for different superheat temperatures
(iii) discharge failure
1) Partial discharge fault
Making a corona discharge and air gap defect model by referring to a CIGRE Method II electrode system structure, as shown in FIG. 3, simulating corona discharge of a metal tip in a transformer by adopting a needle-plate electrode, wherein the electrode distance of a needle plate is 10 mm; the air gap defect adopts a ball electrode, oil-immersed paperboards are tightly bonded through 704 high-voltage silicon rubber, and the inner diameter D of a pore is 3.5 cm. The partial discharge fault gas production test adopts a constant voltage method, 1.2 times of initial discharge voltage is selected as test voltage, and the test voltage of corona discharge and air gap discharge is respectively 24kV and 7.5 kV. And after the external voltage is slowly increased to the test voltage, respectively extracting insulating oil samples at 6h, 12h and 24h of partial discharge, and measuring the components and the content of the dissolved gas in each sample oil.
2) Breakdown fault at power frequency
The industrial frequency breakdown fault gas production test of the ternary mixed insulating oil uses a standard oil cup specified by national standards, the electrode adopts a plate electrode, and the width of an oil gap between the electrodes is 2.5mm, as shown in fig. 4 (a). The insulating oil was allowed to stand for 3 minutes before the first test. After each breakdown of the insulating oil thereafter, the insulating oil was stirred for 1 minute and left to stand for 3 minutes. And (3) boosting at a constant speed of 2kV/s until the insulating oil breaks down, respectively breaking down for 10 times, 20 times, 40 times and 60 times, and extracting the broken-down insulating oil sample to measure the components and the content of each dissolved gas.
In the industrial frequency breakdown fault gas production test of the oil-immersed insulating paperboard, the testing electrode is selected from a column electrode with the same diameter, and the electrode parameters are shown in fig. 4 (b). The thickness of the paperboard is 0.5mm, and the boosting speed is 1 kV/s. After 20, 40 and 60 breakdowns of the insulating oil impregnated paper board occurred, samples of the insulating oil were extracted and the respective dissolved gas components and contents were measured.
3) Flashover fault along surface
A copper needle-plate electrode and a finger-finger electrode are adopted to simulate the oil-paper surface flashover fault under the condition of an internal electrode uneven electric field and a slightly uneven electric field of the transformer, the size of the electrode is shown in figure 5, wherein the radius of curvature of a needle point is 0.25mm, and the radius of a tip end of the finger electrode is 2.5 mm. The boosting speed of the alternating voltage is 3kV/s, and the distance between the high-voltage electrode and the low-voltage electrode is 10 mm. After 3, 5, 10, 15 and 20 surface flashover failures, insulating oil samples were withdrawn and the respective dissolved gas components and contents were measured.
4) Breakdown fault of lightning impulse
The lightning impulse test system is shown in fig. 6 and mainly comprises an impulse voltage generation system, a signal measurement system and an experimental electrode. The external applied voltage of a lightning impulse breakdown fault gas production test is standard lightning impulse voltage waves (1.2 +/-30% mu s and 50 +/-20% mu s), and a pin-plate electrode is adopted to simulate an electrode uneven electric field, wherein the curvature radius of the tip of a tungsten pin electrode is 50 mu m, and the diameter of a copper plate electrode is 50 mm. In an insulating oil lightning impulse breakdown fault gas production test, the length of a pin-plate electrode oil gap is 10mm, and test voltage amplitudes under positive and negative polarities are respectively set to be 50kV and 55kV according to the lightning impulse breakdown voltage of insulating oil. And respectively performing breakdown for 20 times, 40 times and 60 times under the action of positive and negative polarity lightning impulse voltage, then extracting an insulating oil sample and measuring the components and the content of each dissolved gas.
In a lightning impulse breakdown fault gas production test of the oil-immersed insulating paper board, the thickness of the paper board is 1mm, and the amplitude of lightning impulse voltage under positive and negative polarities is 120 kV. And (3) respectively puncturing the oil-immersed insulating paper board for 6 times, 12 times and 18 times under the action of positive and negative polarity lightning impulse voltages, then extracting an insulating oil sample and measuring components and contents of various dissolved gases.
2 characteristics of dissolved gas in oil under thermal and discharge failures
Normal heat aging
CO dissolved in ternary mixed insulating oil in 120 ℃ thermal aging process2Highest content, next to H2、C2H6And CO, the peroxidation of unsaturated fatty acids of vegetable oils at low temperature and overheating is C2H6The main reason for the higher yield. The gas generated by the insulation aging of the ternary mixed oilpaper still contains CO2Mainly, as shown in FIG. 7(b), and CO2Over 85 percent of the total gas, and CO is aged than pure oil2The percentage of total gas is significantly higher.
② overheating fault
Fig. 8(a) shows the dissolved content of each characteristic gas in the ternary mixed insulating oil at different superheating temperatures. When the medium and low temperature is overheated, the gas generated by the ternary insulating oil is mainly CO2High temperature overheating fault H2And the increase in hydrocarbon gas content is significant. The gas generated by the oiled paper insulation at different overheating temperatures is mainly CO2And CO produced by overheating of the oiled paper as compared to overheating of pure oil at the same temperature2The quantity is obviously increased and is about that of CO generated by overheating pure oil23-5 times of the amount of the pure oil, and 2-3 times of the amount of the CO produced by the pure oil, as shown in figure 7 (b). The total amount of gas generated by the three-component mixed oilpaper insulation overheating is obviously more than that generated by the pure oil overheating, but the excessive gas is mainly carbon oxide, even if the hydrocarbon gas generation amount is greatly increased when the oil paper insulation overheating is carried out at high temperature, the total amount of the carbon oxide still accounts for more than 70% of the total gas, and the percentage of the carbon oxide is far higher than that of the pure oil overheating.
(iii) discharge failure
1) Partial discharge fault
Dissolved CO in oil under partial discharge failure2And CO content change is small, and FIG. 9 shows H dissolved in oil under the three-component mixed oilpaper insulation corona discharge fault and air gap discharge fault2And hydrocarbon gas content. H is generated under two partial discharge faults of ternary mixed insulating oil2Similar to the gas quantity and proportion of hydrocarbon gas, the main characteristic gas in partial discharge fault is H2. Except for H2In addition, the two gases most produced under partial discharge are CH4And C2H2And the content is less than H21/3 of (1).
2) Breakdown fault at power frequency
The main gas generated in the breakdown process of the ternary mixed insulating oil is C2H2、H2And C2H4Increasing with increasing number of breakdowns, especially C2H2The increase in the content is most significant during breakdown and is the gas that is the main characteristic of breakdown failure, as shown in fig. 10 (a). Compared with the main characteristic gas C2H2，H2Is less than C2H2Half of the production. The gas generated after the oil-immersed insulating paperboard is punctured for many times is greatly different from that generated after the oil-immersed insulating paperboard is punctured for many times. The most obvious different phenomenon is H generated after the breakdown of the oil-immersed paperboard2The amount is obviously increased compared with the breakdown of pure oil, and the production amount is similar to or slightly higher than C2H2The gas yield of (2) is one of the main characteristic gases of the oil-immersed paperboard under breakdown failure. Secondly, when the oil-immersed insulating paperboard breaks down, C2H2The content of the characteristic gas generated after multiple breakdown is obviously increased along with the increase of the breakdown number. Compared with the breakdown fault of pure oil, C generated after the oil-immersed paperboard is broken down for the same times2H2The larger the amount.
3) Flashover fault along surface
FIG. 11 shows H dissolved in oil after multiple flashover of ternary mixed oilpaper insulation under extremely and slightly non-uniform electric fields2And hydrocarbon gas content variations. H dissolved in oil with increasing flashover times along the surface2And a significant increase in hydrocarbon gas content, in which C is dissolved in the oil2H2And H2The content varies significantly. Compared with 3 flashovers, the oil-paper has 20 surface flashovers of CO in the oil2The content ratio is obviously reduced, and H2And the content of each hydrocarbon gas is obviously increased, wherein C2H2The content ratio is more than 40%. The content and the proportion of C2H2 change obviously before and after the surface flashover fault, so that the carbon dioxide can be used as the characteristic gas of the surface flashover fault of a ternary mixed insulating oil-paper composite system.
4) Breakdown fault of lightning impulse
FIG. 12(a) is the gas generation characteristic of lightning impulse breakdown failure of the insulating oil, and as the number of lightning impulse breakdown increases, the concentration of each characteristic gas in the oil tends to increase, and H in the non-hydrocarbon gas2Content and C in hydrocarbon gas2H2The content is obviously improved. Compared with the trace proportion in the new oil, the positive and negative polarities are punctured for 60 times and then H2And C2H2The sum of the contents of the components reaches 72.84 percent and 66.71 percent, and the gas can be used as the characteristic gas of the lightning impulse breakdown fault of the ternary mixed insulating oil.
Compared with insulating oil, the H dissolved in the oil after the lightning impulse breakdown of the insulating oil-immersed paperboard2And higher content of hydrocarbon gases, in which the oil contains dissolved CH4、C2H4And C2H6The content ratio was significantly increased as shown in fig. 12 (b). H2And C2H2The content of the gas is the highest in the oil, and the difference between the gas and the oil is smaller than the difference of the pure oil after lightning impulse breakdown.
3-ternary mixed oilpaper insulation overheating fault and discharge fault main characteristic gas
The characteristic gas diagnosis method is a diagnosis method for distinguishing transformer faults according to main and secondary gas components and contents. According to the gas generation characteristics under the 2 nd section ternary mixed oilpaper insulation overheating fault and the discharge fault, the main characteristic gas and the secondary characteristic gas generated by different fault types can be summarized into a table 2, so that the fault types of the reaction equipment can be qualitatively determined.
TABLE 2 ternary mixed oilpaper insulation overheating and discharge failure primary and secondary gases
Triangular graphical representation diagnosis model for dissolved gas in oil of overheat fault and discharge fault of 4-hybrid insulating oil transformer
The gas with the largest amount of breakdown failure generation is C2H2And H2The gas generated by partial discharge is mainly H2，C2H2The production amount is less. According to C2H2And H2The relationship between the contents can distinguish the breakdown fault of oil, the breakdown fault of oil-impregnated paper (board) and the partial discharge fault. Thus C is2H2And H2As a characteristic gas for a graphical diagnostic method.
CO removal of gas generated under overheating fault and ternary mixed oilpaper insulation overheating fault2And CO is mainly C2H6、C2H4. Certain amount of C is also generated due to peroxidation of unsaturated fatty acid during normal thermal aging of the ternary mixed insulating oil2H6Possibly interfering with the determination of the result, and C2H4Difficult to form at normal aging temperatures. Combined with electrical fault H2The differentiating action of (1) selecting from C2H4And H2Two gases to distinguish between different overheating faults.
To sum up, select C2H2、H2And C2H4The three gases are used as characteristic gases of a triangle graphic diagnostic method for fault diagnosis of the ternary mixed insulating oil. Are respectively provided with C2H2、H2And C2H4As X, Y and X-axis, the coordinate calculation method in the triangular coordinate system corresponding to each gas sample is shown in formulas (1) to (3).
Wherein X, Y and Z are respectively C2H2、H2、C2H4Coordinates of three characteristic gases in a triangular coordinate system, C (C)2H2)、c(H2)、c(C2H4) The contents of these three gases (μ L/L) were measured. The test results under the ternary mixed oilpaper insulation overheating fault and the electrical fault are substituted into the formulas (1) to (3) to obtain each coordinate value, and the data points are listed in a triangle, as shown in fig. 13. The blue dashed lines demarcate the different failure zones and their boundary conditions are listed in table 3.
TABLE 3 boundary threshold of dissolved gas in oil for overheat and discharge failure of hybrid insulating oil transformer
Validation of 5-triangle-pictorial diagnostic model
To test the accuracy of the triangle diagnostics of fig. 13, the following three types of failure were used for verification of gas production characteristics. First, when the field transformer normally works, the temperature of the insulating oil is generally lower than 90 ℃, and if the local oil temperature reaches 120 ℃, it is considered as low-temperature overheating, so the gas generation of the insulating oil and the oil-immersed insulating paper at 120 ℃ should fall in the region T1 in fig. 13. Secondly, lightning impulse voltages with positive and negative polarities are used for carrying out breakdown on the ternary mixed insulating oil-immersed paper board (1mm) for multiple times, and data points of impulse breakdown gas generation should fall into a breakdown discharge area. And thirdly, simulating the surface flashover fault of the oil-paper interface, wherein a discharge channel is formed in the insulating oil in the flashover process, so that data points fall into the breakdown fault area of the insulating oil after multiple surface flashovers. Finally, the gas production conditions under the three faults are substituted into the triangular diagnostic diagram, and the result is shown in fig. 14. The results show that all three faults fall into the corresponding regions, and the result is verified to be C2H2、H2、C2H4The triangles for the three characteristic gases illustrate the accuracy of the fault diagnostics.
Gas distribution coefficient: according to the national Standard gas chromatography determination of the content of dissolved gas components in insulating oil (GB/T176232017), the distribution coefficient of the ternary mixed insulating oil at 50 ℃ is shown in Table 4.
TABLE 4 ternary mixed insulating oil gas distribution coefficient
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (5)
1. The method for analyzing the fault of the hybrid insulating oil transformer based on the dissolved gas in the oil is characterized by comprising the following steps of: the method comprises the following steps:
s1: carrying out a test of gas production characteristics under thermal fault and discharge fault;
s2: analyzing the characteristics of dissolved gas in oil under thermal fault and discharge fault;
s3: researching characteristic gas under the ternary mixed oilpaper insulation overheating fault and the discharge fault;
s4: and establishing a triangular graphic diagnosis model of dissolved gas in oil of the overheat fault and the discharge fault of the hybrid insulating oil transformer.
2. The method for analyzing the failure of the hybrid insulating oil transformer based on the dissolved gas in the oil according to claim 1, wherein: the S1 specifically includes:
normal heat aging
In a normal thermal aging gas production test of ternary mixed insulating paper, the thermal aging temperature is 120 ℃, the moisture content of the dried ternary mixed insulating oil is about 14ppm, and the moisture content of the insulating paper is less than 1%; the 12 wide-mouth bottles with 500mL are divided into 2 groups, namely a pure oil thermal aging group and an oil paper thermal aging group; 500mL of ternary mixed insulating oil is poured into the pure oil thermal aging group, insulating paper is added into the oil paper thermal aging group after the insulating oil is removed, and the oil paper mass ratio is controlled to be 20: 1; placing all the jars under the condition of 60 ℃/50Pa for 24h to finish the oil immersion process, and finally sealing all the jars in a nitrogen environment;
aging the samples immersed in the oil at 120 ℃, wherein the sampling interval is 10 days, and testing the components and the content of the dissolved gas in the oil sampled each time until 6 samples are taken;
② overheating fault
According to different temperatures of the hot spots, transformer overheating faults are divided into low-temperature overheating, namely, the temperature is less than 300 ℃, medium-temperature overheating, namely 300-700 ℃, and high-temperature overheating, namely, the temperature is more than or equal to 700 ℃; the method is characterized in that the method adopts a tubular muffle furnace heating mode to simulate overheating at different temperatures, and comprises the tubular muffle furnace and a special heating pipe; the sample amount added into the sample chamber is controlled in each test, the adding amount of insulating oil is 30mL, the insulating oil in the oil-impregnated paper sample is 30mL, the mass of the insulating paper is 1.3g, and the oil-paper ratio is kept to be about 20: 1; during the test, the tubular muffle furnace is used for heating to a specific temperature, the gas generated by overheating of the sample is led out to a closed container filled with 500mL of insulating oil through the sample tube, and the gas generated by overheating can be dissolved in the degassed insulating oil; when the overheating test time is up, taking out the heating pipe and standing for 5 minutes to enable the generated gas to be uniformly dissolved in 500mL of insulating oil; finally, taking an insulating oil sample to test the content of dissolved gas in the insulating oil sample;
(iii) discharge failure
1) Partial discharge fault
Making a corona discharge and air gap defect model according to a CIGRE Method II electrode system structure, and simulating corona discharge of a metal tip in a transformer by adopting a needle-plate electrode, wherein the distance between the needle plate electrodes is 10 mm; the air gap defect is formed by adopting a ball electrode and tightly bonding oil-immersed paperboards through 704 high-voltage silicon rubber, and the inner diameter D of a pore is 3.5 cm; the partial discharge fault gas production test adopts a constant voltage method, 1.2 times of initial discharge voltage is selected as test voltage, and the test voltage of corona discharge and air gap discharge is respectively 24kV and 7.5 kV; after the external applied voltage is slowly increased to the test voltage, respectively extracting insulating oil samples when partial discharge is carried out for 6 hours, 12 hours and 24 hours, and measuring the components and the content of dissolved gas in each sample oil;
2) breakdown fault at power frequency
The industrial frequency breakdown fault gas production test of the ternary mixed insulating oil uses a standard oil cup specified by national standard, the electrode adopts a plate electrode, and the oil gap width between the electrodes is 2.5 mm; standing for 3 minutes before the first test of the insulating oil; after each time of breakdown of the insulating oil, stirring the insulating oil for 1 minute and standing for 3 minutes; uniformly boosting at a speed of 2kV/s until the insulating oil breaks down, respectively breaking down for 10 times, 20 times, 40 times and 60 times, extracting the broken-down insulating oil sample, and measuring the components and the content of each dissolved gas;
in a power frequency breakdown fault gas production test of the oil-immersed insulating paperboard, a testing electrode selects a column electrode with equal diameter; the thickness of the paperboard is 0.5mm, and the boosting rate is 1 kV/s; after 20 times, 40 times and 60 times of breakdown of the insulating oil-immersed paperboard, extracting an insulating oil sample and measuring components and contents of various dissolved gases;
3) flashover fault along surface
Simulating the oil-paper surface flashover fault under the condition of an internal electrode uneven electric field and a slightly uneven electric field of the transformer by using a copper needle-plate electrode and a finger-finger electrode, wherein the radius of curvature of a needle point is 0.25mm, and the radius of the tip end of the finger electrode is 2.5 mm; the boosting rate of the alternating voltage is 3kV/s, and the distance between the high-voltage electrode and the low-voltage electrode is 10 mm; after 3, 5, 10, 15 and 20 surface flashover faults occur, extracting an insulating oil sample and measuring the components and the content of each dissolved gas;
4) breakdown fault of lightning impulse
The lightning impulse test system consists of an impulse voltage generation system, a signal measurement system and an experimental electrode; the external applied voltage of a lightning impulse breakdown fault gas production test is standard lightning impulse voltage waves, namely 1.2 +/-30% mu s and 50 +/-20% mu s, and a pin-plate electrode is adopted to simulate an electrode uneven electric field, wherein the curvature radius of the tip of a tungsten pin electrode is 50 mu m, and the diameter of a copper plate electrode is 50 mm; in an insulating oil lightning impulse breakdown fault gas production test, the length of a pin-plate electrode oil gap is 10mm, and test voltage amplitudes under positive and negative polarities are respectively set to be 50kV and 55kV according to the lightning impulse breakdown voltage of the insulating oil; respectively performing breakdown for 20 times, 40 times and 60 times under the action of positive and negative polarity lightning impulse voltage, then extracting an insulating oil sample and measuring components and contents of each dissolved gas;
in a lightning impulse breakdown fault gas production test of the oil-immersed insulating paper board, the thickness of the paper board is 1mm, and the amplitude of lightning impulse voltage under positive and negative polarities is 120 kV; and (3) respectively puncturing the oil-immersed insulating paper board for 6 times, 12 times and 18 times under the action of positive and negative polarity lightning impulse voltages, then extracting an insulating oil sample and measuring components and contents of various dissolved gases.
3. The method for analyzing the failure of the hybrid insulating oil transformer based on the dissolved gas in the oil according to claim 1, wherein: the S2 specifically includes:
normal heat aging
CO dissolved in ternary mixed insulating oil in 120 ℃ thermal aging process2Highest content, next to H2、C2H6And CO, the peroxidation of unsaturated fatty acids of vegetable oils at low temperature and overheating is C2H6The reason for the higher yield; the gas generated by the insulation aging of the ternary mixed oilpaper still contains CO2Mainly of CO, and2over 85 percent of the total gas, and CO is aged than pure oil2The percentage of total gas is significantly higher;
② overheating fault
When the medium and low temperature is overheated, the gas generated by the ternary insulating oil is CO2High temperature overheating fault H2And a significant increase in hydrocarbon gas content; the gas generated by the oiled paper insulation at different overheating temperatures is CO2And CO produced by overheating of the oiled paper as compared to overheating of pure oil at the same temperature2The amount is obviously increased, and CO is generated for the overheating of pure oil23-5 times of the amount of the pure oil, wherein the CO gas production is 2-3 times of the pure oil overheating; the total amount of gas generated by the ternary mixed oilpaper insulation overheating is obviously more than that generated by the pure oil overheating, the extra gas is carbon oxide, even if the hydrocarbon gas generation amount is greatly increased when the ternary mixed oilpaper insulation overheating is performed at high temperature, the total amount of the carbon oxide still accounts for more than 70% of the total gas, and the percentage of the carbon oxide is far higher than that of the pure oil overheating;
(iii) discharge failure
1) Partial discharge fault
Dissolved CO in oil under partial discharge failure2And little change in CO content; h is generated under two partial discharge faults of ternary mixed insulating oil2And hydrocarbon gasThe gas quantity and proportion of the body are similar, and the characteristic gas under partial discharge fault is H2(ii) a Except for H2In addition, the two gases most produced under partial discharge are CH4And C2H2And the content is less than H21/3 of (1);
2) breakdown fault at power frequency
The gas generated in the breakdown process of the ternary mixed insulating oil is C2H2、H2And C2H4Increasing with increasing number of breakdowns, especially C2H2The content of the gas is increased most obviously in the breakdown process and is the characteristic gas of breakdown failure; compared with the characteristic gas C2H2，H2Is less than C2H2Half of the production; the gas generated after the oil-immersed insulating paperboard is punctured for many times is greatly different from that generated after the oil-immersed insulating paperboard is punctured for many times; the most obvious different phenomenon is H generated after the breakdown of the oil-immersed paperboard2The amount is obviously increased compared with the breakdown of pure oil, and the production amount is similar to or slightly higher than C2H2The gas yield of (2) is one of characteristic gases of the oil-immersed paperboard under breakdown failure; secondly, when the oil-immersed insulating paperboard breaks down, C2H2The content of the characteristic gas which is generated in a large amount after multiple breakdowns is obviously increased along with the increase of the number of breakdowns; compared with the breakdown fault of pure oil, C generated after the oil-immersed paperboard is broken down for the same times2H2The amount is larger;
3) flashover fault along surface
H dissolved in oil with increasing flashover times along the surface2And a significant increase in hydrocarbon gas content, in which C is dissolved in the oil2H2And H2The content changes remarkably; compared with 3 flashovers, the oil-paper has 20 surface flashovers of CO in the oil2The content ratio is obviously reduced, and H2And the content of each hydrocarbon gas is obviously increased, wherein C2H2The content ratio exceeds 40 percent; the content and the proportion of C2H2 change obviously before and after the surface flashover fault, and the carbon dioxide is used as the characteristic gas of the surface flashover fault of the ternary mixed insulating oil-paper composite system;
4) breakdown fault of lightning impulse
With the increase of the lightning impulse breakdown times, the concentration of each characteristic gas in the oil shows an ascending trend, and H in the non-hydrocarbon gas2Content and C in hydrocarbon gas2H2The content is obviously improved; compared with the trace proportion in the new oil, the positive and negative polarities are punctured for 60 times and then H2And C2H2The sum of the content ratios is up to 72.84% and 66.71%, and the sum is used as the characteristic gas of the lightning impulse breakdown fault of the ternary mixed insulating oil;
compared with insulating oil, the H dissolved in the oil after the lightning impulse breakdown of the insulating oil-immersed paperboard2And higher content of hydrocarbon gases, in which the oil contains dissolved CH4、C2H4And C2H6The content ratio is obviously improved; h2And C2H2The content of the gas is the highest in the oil, and the difference between the gas and the oil is smaller than the difference of the pure oil after lightning impulse breakdown.
4. The method for analyzing the failure of the hybrid insulating oil transformer based on the dissolved gas in the oil according to claim 1, wherein: the S3 specifically includes:
the characteristic gas diagnosis method is a diagnosis method for distinguishing transformer faults according to the components and the contents of main and secondary gases; and (4) qualitatively reflecting the fault type of the equipment according to the gas production characteristics under the ternary mixed oil paper insulation overheating fault and the discharge fault.
5. The method for analyzing the failure of the hybrid insulating oil transformer based on the dissolved gas in the oil according to claim 1, wherein: the S4 specifically includes:
the gas with the largest amount of breakdown failure generation is C2H2And H2The gas generated by partial discharge is H2，C2H2The production amount is less; according to C2H2And H2Distinguishing the relation among the contents, namely distinguishing an oil breakdown fault, an oil-impregnated paper breakdown fault and a partial discharge fault; c is to be2H2And H2Characteristic gases as a graphic diagnostic;
CO removal of gas generated under overheating fault and ternary mixed oilpaper insulation overheating fault2And CO is other than C2H6、C2H4(ii) a Certain amount of C is also generated due to peroxidation of unsaturated fatty acid during normal thermal aging of the ternary mixed insulating oil2H6Will interfere with the determination of the result, and C2H4Difficult to form at normal aging temperatures; combined with electrical fault H2The differentiating action of (1) selecting from C2H4And H2Two gases to distinguish different overheating faults;
to sum up, select C2H2、H2And C2H4The three gases are used as characteristic gases of a triangle graphic diagnostic method and are used for fault diagnosis of the ternary mixed insulating oil; are respectively provided with C2H2、H2And C2H4As X, Y and X axis, the coordinate calculation method in the triangular coordinate system corresponding to each gas sample is shown in formulas (1) to (3);
wherein X, Y and Z are respectively C2H2、H2、C2H4Coordinates of three characteristic gases in a triangular coordinate system, C (C)2H2)、c(H2)、c(C2H4) The content of the three gases is respectively, and the unit is mu L/L; and substituting the test results under the ternary mixed oilpaper insulation overheating fault and the electrical fault into the formulas (1) to (3) to obtain coordinate values, and listing data points in a triangle.
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