CN117129789B - Health state assessment method for power transformer insulation system - Google Patents
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- 238000009413 insulation Methods 0.000 title claims abstract description 95
- 230000036541 health Effects 0.000 title claims abstract description 63
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- 238000001816 cooling Methods 0.000 claims description 7
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- 230000003862 health status Effects 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 230000007613 environmental effect Effects 0.000 claims description 5
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
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Abstract
The invention provides a health state evaluation method of a power transformer insulation system, which comprises the following steps: setting up an aging box, and putting the insulation system into the aging box to accelerate aging; performing FDS frequency domain spectrum test, tensile test and hot spot temperature test on the winding insulation, the lead insulation and the sleeve insulation by using a test instrument, and calculating according to test results to obtain health indexes HI1, HI2 and HI3; constructing a basic evaluation model according to state quantity information of the power transformer; according to the basic evaluation model and combining health indexes HI1, HI2 and HI3, calculating a comprehensive evaluation model of the insulation system; acquiring historical record data of the transformer to be evaluated, and correcting the comprehensive evaluation model to obtain a final evaluation model; and acquiring the operation data of the transformer in real time, inputting the operation data into a final evaluation model, and obtaining an evaluation result. The invention fully considers the factors such as the load level, the operation environment, the partial discharge and the like of the transformer, accords with the actual operation state of the transformer, and improves the accuracy of the health state evaluation of the insulation system.
Description
Technical Field
The invention relates to the technical field of power transformers, in particular to a health state assessment method of a power transformer insulation system.
Background
The power transformer is core power equipment for electric energy transmission and energy conversion in a power system, and is widely applied to a 110kV and above voltage class power grid. In the actual operation process, the oil immersed power transformer insulation system is gradually deteriorated under the influence of electric stress, thermal stress, environmental factors and the like, so that moisture, acid products and the like in an oil tank are gradually increased, the insulation performance of the power transformer is easily reduced due to the aging of the insulation system, even insulation failure is induced, and the safe and stable operation of the transformer and the power system is seriously threatened. Therefore, the reliability of the transformer insulation system is effectively judged, and the method has great significance in ensuring the safe and stable operation of the transformer.
The insulation system of the power transformer comprises a winding, a lead wire, a sleeve and other components, wherein the reliability of the insulation system is determined by the components together and is related to each other. To evaluate the impact of electrical, thermal and environmental factors on an insulation system, an aging box is typically constructed and the insulation system is placed in the aging box for testing to explore the functional relationship between the insulation system health index and the impact factors. However, the existing aging box needs to open the box cover for multiple times to take out the lead wires in the aging test process, the elongation at break retention rate of the lead wires is measured, and the oil temperature and the water content in the aging box can be influenced by uncovering each time, so that the accuracy of an evaluation model is low, and the evaluation of the health state of an insulation system is caused to deviate. In addition, the existing evaluation model does not fully consider the influence of factors such as transformer load level, operation environment, partial discharge and the like on the evaluation, and considered factors are not comprehensive enough, so that a large improvement space exists.
Disclosure of Invention
The invention aims to provide a health state evaluation method of a power transformer insulation system, which solves the problem of low accuracy of an evaluation model of the power transformer insulation system in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme: a health state evaluation method of an insulation system of a power transformer comprises the following steps: s100, constructing an aging box of an insulation system of a power transformer, and putting a plurality of groups of insulation systems into different aging boxes to perform accelerated aging treatment, wherein the insulation systems comprise winding insulation, lead insulation and sleeve insulation which are connected according to actual structures; s200, respectively performing FDS frequency domain spectrum test, tensile test and hot spot temperature test on the winding insulation, the lead insulation and the sleeve insulation by using a test instrument at different ageing temperatures and times, and calculating according to each test result to obtain a health index HI1, a health index HI2 and a health index HI3; s300, constructing a basic evaluation model according to state quantity information of the power transformer, wherein the state quantity information comprises life expectancy, operational years, load level and operation environment; s400, calculating a comprehensive evaluation model of the insulation system according to the basic evaluation model and combining the health index HI1, the health index HI2 and the health index HI3; s500, acquiring historical record data of the transformer to be evaluated, and correcting the comprehensive evaluation model to obtain a final evaluation model; s600, operation data of the power transformer are obtained in real time and are input into the final evaluation model, and a health state evaluation result of the insulation system of the power transformer is obtained.
In step S100, the aging box includes a box body, a winding, a lead wire, a sleeve, an oil storage box, a temperature controller, a dielectric spectrometer, a terminal, a multi-path temperature tester, a tension device and a vacuum pump, wherein the winding, the lead wire and the sleeve are sequentially connected, the winding and the lead wire are arranged inside the box body, the sleeve is fixedly arranged on the upper portion of the box body, insulating oil is filled inside the box body, an oil inlet, an oil outlet and an extraction opening are arranged on the side portion of the box body, the inlet of the oil storage box is communicated with the oil outlet, the outlet of the oil storage box is connected with the oil inlet through an oil pump, a heating pipe is arranged inside the oil storage box, the heating pipe is electrically connected with the terminal through the temperature controller, the extraction opening is connected with the vacuum pump, one end of the dielectric spectrometer is connected with the winding, the other end of the dielectric spectrometer is connected with the terminal, the input end of the multi-path temperature tester is connected with the sleeve and the lead wire, the output end of the multi-path temperature tester is connected with the terminal, and the tension device is arranged on the side wall of the box for carrying out tensile test on the lead wire so as to obtain the elongation at break of insulation of the lead wire.
As a preferred scheme, the tension device comprises a motor, a first rack, a second rack, a driving gear, a connecting rod assembly and a locking sleeve, wherein the motor is fixedly arranged on the outer wall of the box body, the output end of the motor is connected with an output shaft, the output shaft penetrates through the wall surface of the box body, the end part of the output shaft is connected with the driving gear, the first rack and the second rack are positioned on two sides of the driving gear and are in meshed connection with the driving gear, the first rack and the second rack are both in sliding connection with the inner wall of the box body through guide rails, the ends of the first rack and the second rack are respectively connected with the locking sleeve through the connecting rod assembly, the lead comprises a lead insulator and an inner stranded wire, and the locking sleeve is used for being inserted between the lead insulator and the inner stranded wire and clamping the lead insulator; the connecting rod assembly comprises a vertical rod, a cross rod and a chuck rod which are positioned on the same horizontal plane, one end of the vertical rod is fixedly connected with the first rack or the second rack, the other end of the vertical rod is connected with the end part of the cross rod, the other end part of the cross rod is connected with the chuck rod, and the other end part of the chuck rod is fixedly connected with the locking sleeve; pressure sensors are arranged between the upper chuck rod and the lower chuck rod, two ends of each pressure sensor are respectively connected to the two chuck rods through pull ropes, and distance sensors are arranged at corresponding positions between the upper chuck rod and the lower chuck rod.
As the preferable scheme, the lock sleeve comprises a lock sleeve body, an outer lock sleeve and an inner supporting tube, wherein the side part of the lock sleeve body is fixedly connected with the end part of the chuck rod, one end part of the inner supporting tube is fixedly arranged at the end part of the lock sleeve body, the other end of the inner supporting tube is used for being inserted between a lead insulator and an inner stranded wire, one end part of the outer lock sleeve extends into the lock sleeve body and is in threaded connection with the lock sleeve body, and the thickness of the inner wall of the other end part of the outer lock sleeve is increased gradually from outside to inside and is used for clamping the lead insulator.
As a preferred embodiment, the health index HI2 is calculated based on the test result of the tensile test, comprising the steps of: under different ageing temperatures and ageing times, carrying out tensile tests on lead insulation to obtain a plurality of groups of elongation at break retention rates; establishing a relation chart of elongation at break retention and aging time at different aging temperatures; fitting the relation graph by adopting a multiple nonlinear regression method to obtain a regression function M; the reduction of the elongation at break to 50% is taken as a failure threshold for the insulation of the lead, and the health index h2= (50/M).
Preferably, the calculation formula of the basic evaluation model is as follows:
；
；
in the above-mentioned method, the step of,health index of the evaluation model based on +.>For the initial health index of the device, B is the aging coefficient,for the current year->For the year of equipment operation, < > for>For the original intended service life, < >>For load correction factor, ++>Is an environmental correction factor.
As a preferred solution, the comprehensive evaluation model HIcom of the insulation system is:
in the above, the->Is a constant, its value is equal to->Is related to the size of (a).
As a preferable scheme, the history record data comprises equipment operation time T, iron core grounding current I, transformer appearance grade L, sleeve reliability grade R, cooling mode, whether family defects exist, failure defect times n, whether short circuit exists in a near zone or not, and whether partial discharge exists or not; the health index H for the final assessment model is:
in the above-mentioned method, the step of,health index for comprehensive assessment model +.>For the comprehensive correction factor->Is the correction factor of the mth history data.
Compared with the prior art, the invention has the beneficial effects that: the method comprises the steps of placing the windings, the leads and the sleeve in an aging box, carrying out FDS frequency domain spectrum test, tensile test and hot spot temperature test on the windings, the leads and the sleeve according to actual structures in series, obtaining corresponding health indexes, constructing a comprehensive evaluation model by combining a basic evaluation model, and finally correcting the comprehensive evaluation model according to historical record data of a transformer to obtain a final evaluation model, wherein the model fully considers factors such as the load level, the running environment and partial discharge of the transformer, accords with the actual running state of the transformer, and improves the reliability evaluation accuracy of an insulation system. Moreover, the tensile device is adopted to carry out tensile test on the lead in the ageing oven, the ageing oven is not required to be opened, the lead is taken to the outside for detection, the deviation of oil temperature and water content caused by frequent opening of the oven cover is avoided, and the accuracy of the model and the simplicity of the test are further improved.
Drawings
The disclosure of the present invention is described with reference to the accompanying drawings. It is to be understood that the drawings are designed solely for the purposes of illustration and not as a definition of the limits of the invention. In the drawings, like reference numerals are used to refer to like parts. Wherein:
FIG. 1 is a flow chart of a health status assessment method according to an embodiment of the invention;
FIG. 2 is a schematic view of an aging oven according to an embodiment of the present invention;
FIG. 3 is a schematic structural view of a tension device according to an embodiment of the present invention;
fig. 4 is a vertical cross-sectional view of a tension device according to an embodiment of the present invention.
Reference numerals in the drawings: 1 box, 2 tension device, 2.0 guide rail, 2.1 first rack, 2.2 second rack, 2.3 driving gear, 2.4 vertical rod, 2.5 horizontal rod, 2.6 locking sleeve, 2.61 locking sleeve body, 2.62 outer locking sleeve, 2.63 inner supporting tube, 2.7 clamping head rod, 2.8 pressure sensor, 2.9 distance sensor, 3 high-voltage winding, 4 low-voltage winding, 5 high-voltage lead, 5.1 lead insulator, 5.2 inner stranded wire, 6 low-voltage lead, 7 high-voltage sleeve, 8 low-voltage sleeve, 9 dielectric spectrometer, 10 multi-channel temperature tester, 11 terminal machine, 12 oil outlet, 13 oil storage tank, 14 heating tube, 15 temperature controller, 16 oil pump, 17 oil inlet, 18 air extraction opening, 19 vacuum pump, 20 temperature sensor.
Detailed Description
It is to be understood that, according to the technical solution of the present invention, those skilled in the art may propose various alternative structural modes and implementation modes without changing the true spirit of the present invention. Accordingly, the following detailed description and drawings are merely illustrative of the invention and are not intended to be exhaustive or to limit the invention to the precise form disclosed.
An embodiment according to the invention is shown in connection with fig. 1. An evaluation method for the health state of an insulation system of a power transformer comprises the following steps:
s100, constructing an aging box of an insulation system of the power transformer, putting a plurality of groups of insulation systems into different aging boxes for accelerated aging treatment, wherein the insulation systems comprise winding insulation, lead insulation and sleeve insulation which are connected according to actual structures, as shown in fig. 2.
And S200, respectively performing FDS frequency domain spectrum test, tensile test and hot spot temperature test on the winding insulation, the lead insulation and the sleeve insulation by using a test instrument at different ageing temperatures and times, and calculating according to test results to obtain a health index HI1, a health index HI2 and a health index HI3.
According to the test result of the FDS frequency domain spectrum test, calculating to obtain a health index HI1, wherein the method comprises the following steps of:
FDS frequency domain spectrum test is carried out on winding insulation, and dielectric constant frequency domain spectrum is obtained.
And calculating dielectric loss factors according to the dielectric constant frequency domain spectrum and based on an XY model of winding insulation.
The XY model for winding insulation is specifically as follows: and building an XY model according to the number of layers of the insulating plates of the winding, the thickness, the distance of the oil duct, the structures and the electrical parameters of the number of cushion blocks and the number of stays. The X value of the XY model is the ratio of the total thickness of the insulating plate to the main insulation thickness between the high-voltage winding and the low-voltage winding, and the Y value is the ratio of the total width of the stay to the average circumference of the main insulation between the high-voltage winding and the low-voltage winding.
And establishing a fitting function d according to the dielectric loss factors and the aging time corresponding to the dielectric loss factors, and finally obtaining the health index HI1 of winding insulation.
The formula of the health index HI1 for winding insulation is as follows:
in the above-mentioned method, the step of,health index for winding insulation, +.>For the life expectancy of the winding insulation, +.>For loss factor, ++>Respectively constant, d is aging time, +.>Dielectric constant frequency domain spectrum of insulating oil, j is imaginary part,>for the dc conductivity of the insulating oil at temperature T, and (2)>Is vacuum dielectric constant, +.>In order to be of an angular frequency,frequency domain spectrum of dielectric constant for winding insulation, +.>The dielectric constant frequency domain spectrum of the winding insulating plate is obtained, X is the X value of an XY model, and Y is the Y value of the XY model.
B. According to the test result of the tensile test, calculating and obtaining the health index HI2, wherein the method comprises the following steps of:
and under different ageing temperatures and ageing times, carrying out tensile tests on the lead insulation to obtain a plurality of groups of elongation at break retention rates.
And (5) establishing a graph of elongation at break retention and ageing time at different ageing temperatures.
Fitting the relation diagram by adopting a multi-element nonlinear regression method to obtain a regression function M of the elongation at break retention rate.
Defining M as a binary nonlinear regression function of aging temperature t and aging time M, the formula is as follows:
；
wherein a, b, c, d, e are fitting coefficients.
The reduction of the elongation at break to 50% is taken as a failure threshold for the insulation of the lead, and the health index h2= (50/M).
C. According to the test result of the hot spot temperature, calculating and obtaining a health index HI3, wherein the method comprises the following steps of:
(1) Measuring the temperature of a plurality of positions on the sleeve, and estimating the temperature of hot spots in the sleeve, wherein the method specifically comprises the following steps:
the temperature T1 of the upper porcelain bushing and the temperature T2 of the lower porcelain bushing of the sleeve are measured respectively, and the temperature T3 of insulating oil in the box body is measured; the temperature of the hot spot in the sleeveThe method comprises the following steps:
；
(2) The insulating polymerization degree of the sleeve after the aging time d is set asThe health index HI3 of the bushing insulation is formulated as follows:
；
in the above-mentioned method, the step of,for the initial insulation polymerization degree, +.>Is an insulating factor, A is a front factor, d is aging time, E is sleeve activation energy, R is ideal gas constant value, < >>For the temperature of the hot spot in the bushing, +.>Absolute temperature.
S300, constructing a basic evaluation model according to state quantity information of the power transformer, wherein the state quantity information comprises life expectancy, operational years, load levels and operation environments.
The calculation formula of the basic evaluation model is as follows:
；
in the above-mentioned method, the step of,health index of the evaluation model based on +.>For the initial health index of the device, B is the aging coefficient,for the current year->For the year of equipment operation, < > for>For the original intended service life, < >>For load correction factor, ++>Is an environmental correction factor.
S400, calculating a comprehensive evaluation model of the insulation system according to the basic evaluation model and combining the health index HI1, the health index HI2 and the health index HI3.
The comprehensive evaluation model HIcom of the insulation system is:
in the above, the->Is a constant, its value is equal to->Is related to the size of (a).
S500, historical record data of the transformer to be evaluated is obtained, and the comprehensive evaluation model is corrected to obtain a final evaluation model.
In the embodiment of the invention, the history record data comprises equipment operation time T, iron core grounding current I, transformer appearance grade L, sleeve reliability grade R, cooling mode, whether family defects exist, failure defect times n, whether short circuit exists in a near zone or not, and whether partial discharge exists or not; the health index H for the final assessment model is:
in the above-mentioned method, the step of,health index for comprehensive assessment model +.>For the comprehensive correction factor->Is the correction factor of the mth history data.
Wherein, for the equipment operation time T, the unit is year. K1=1 when 0.ltoreq.t.ltoreq.5; k1=1.01 when 5 < T is less than or equal to 10; k1=1.02 when 10 < T is less than or equal to 20; k1=1.05 when 20 < T is less than or equal to 30; k1=1.09 when T > 30.
For core ground current I, the unit is a. When i=0, k2=1; k2=1.05 when 0 < I is less than or equal to 0.1A; k2=1.1 when 0.1A < I is less than or equal to 0.3A; k2=1.2 when I > 0.3A.
For the transformer appearance grade L, k3=0.9+0.1l, where L takes values of 1, 2, …, 5 (grade 1 indicates the best appearance condition, no damage).
And for the reliability grade R of the sleeve, the value of the reliability grade R of the sleeve is 1-5. K4=0.9 when r=1; k4=1 when r=2; k4=1.1 when r=3; when r=4, k4=1.2; when r=5, k4=1.4.
For cooling modes, oil immersed self-cooling ONAN and oil immersed air cooled ONAF, k5=1; forced oil circulation cooling OF, k5=0.96; forced pilot oil circulated cooling OD, k5=0.95.
For the presence or absence of family defects, k6=0.96 if the problem has never occurred with the same series of devices; k6=1 if the same series of devices have few defects, but do not jeopardize operation; if the same series of devices have repeated faults and have potential safety hazards, k6=1.04.
For the failure defect number n, the failure of nearly five years, defect number n. When n=0, k7=0.96; when n=1, k7=1; k7=1.04 when n is 2, 3, 4; k7=1.2 when n is 5, 6, …, 10;
k7=1.4 when n > 10.
Regarding the presence or absence of a short circuit in the near zone, k8=1.04 if an excessive short circuit in the near zone occurs; if no short-circuiting of the near zone occurs, k8=1.
For the presence or absence of partial discharge, k9=1.2 if there is a partial discharge phenomenon; if there is no partial discharge, k9=1. If a certain index is default, the corresponding correction coefficient of the index is 1.
S600, operation data of the power transformer are obtained in real time and are input into a final evaluation model, and a health state evaluation result of the insulation system of the power transformer is obtained. For example: if the calculated health index H is 1.6, it is known from the following table 1 that the health state of the insulation system of the power transformer is at the initial stage of the normal aging phenomenon, and the risk of failure is low, so that the insulation system can be used normally.
Table 1:
referring to fig. 2, in step S100, an aging box of an insulation system of a power transformer is built, the aging box comprises a box body 1, windings, leads, a sleeve, an oil storage box 13, a temperature controller 15, a dielectric spectrometer 9, a terminal 11, a multi-path temperature tester 10, a tension device 2 and a vacuum pump 19, the windings, the leads and the sleeve are sequentially connected, the windings and the leads are arranged in the box body 1, the sleeve is fixedly arranged at the upper part of the box body 1, insulating oil is filled in the box body 1, an oil inlet 17, an oil outlet 12 and an extraction opening 18 are arranged on the side part of the box body 1, the inlet of the oil storage box 13 is communicated with the oil outlet 12, the outlet of the oil storage box is connected with the oil inlet 17 through an oil pump 16, a heating pipe 14 is arranged in the oil storage box 13, the heating pipe 14 is electrically connected with the terminal 11 through the temperature controller 15, the extraction opening 18 is connected with the vacuum pump 19, one end of the dielectric spectrometer 9 is connected with the windings, the other end of the multi-path temperature tester 10 is connected with the sleeve and the leads, the output end of the multi-path temperature tester is connected with the terminal 11, the output end of the winding is connected with the terminal 11, the tension device 2 is arranged on the side wall of the box body 1 for conducting a tensile test to obtain the elongation at break of the leads insulation.
Referring to fig. 3, the tension device 2 includes a motor, a first rack 2.1, a second rack 2.2, a driving gear 2.3, a connecting rod assembly and a locking sleeve 2.6, wherein the motor is fixedly arranged on the outer wall of the box 1, the output end of the motor is connected with an output shaft, the output shaft passes through the wall surface of the box 1, the end of the output shaft is connected with the driving gear 2.3, the first rack 2.1 and the second rack 2.2 are positioned at two sides of the driving gear 2.3 and are in meshed connection with the driving gear 2.3, the first rack 2.1 and the second rack 2.2 are both in sliding connection with the inner wall of the box 1 through a guide rail 2.0, the ends of the first rack 2.1 and the second rack 2.2 are respectively connected with the locking sleeve 2.6 through the connecting rod assembly, and the lead wire comprises a lead insulator 5.1 and an inner stranded wire 5.2, and the locking sleeve 2.6 is used for being inserted between the lead insulator 5.1 and the inner stranded wire 5.2 and clamping the lead insulator 5.1. The connecting rod assembly comprises a vertical rod 2.4, a cross rod 2.5 and a chuck rod 2.7 which are positioned on the same horizontal plane, one end of the vertical rod 2.4 is fixedly connected with the first rack 2.1 or the second rack 2.2, the other end of the vertical rod is connected with the end part of the cross rod 2.5, the other end part of the cross rod 2.5 is connected with the chuck rod 2.7, and the other end part of the chuck rod 2.7 is fixedly connected with the locking sleeve 2.6; a pressure sensor 2.8 is arranged between the upper chuck rod 2.7 and the lower chuck rod 2.7, two ends of the pressure sensor 2.8 are respectively connected to the two chuck rods 2.7 through pull ropes, and a distance sensor 2.9 is arranged between the upper chuck rod 2.7 and the lower chuck rod 2.7 at a corresponding position.
Referring to fig. 4, the lock sleeve 2.6 includes a sleeve body 2.61, an outer sleeve 2.62 and an inner supporting tube 2.63, wherein the side portion of the sleeve body 2.61 is fixedly connected with the end portion of the chuck rod 2.7, one end portion of the inner supporting tube 2.63 is fixedly arranged at the end portion of the sleeve body 2.61, the other end of the inner supporting tube is used for being inserted between the lead insulator 5.1 and the inner stranded wire 5.2, one end portion of the outer sleeve 2.62 extends into the sleeve body 2.61 and is in threaded connection with the inner sleeve body, and the thickness of the inner wall of the other end portion of the outer sleeve is increased from outside to inside uniformly so as to clamp the lead insulator 5.1.
When a tensile test is carried out, only the motor is required to be started, the motor drives the first rack and the second rack to move reversely through the driving gear, so that the lead insulator is stretched, the length of the lead at the time of being broken is obtained through the cooperation of the pressure sensor and the distance sensor, and the elongation at break retention rate of the lead insulation is calculated. The aging box does not need to be opened, the lead is taken to the outside for detection, so that deviation of oil temperature and water content caused by frequent opening of the box cover is avoided, and the accuracy of the model is further improved.
In summary, the beneficial effects of the invention include: the method comprises the steps of placing the windings, the leads and the sleeve in an aging box, carrying out FDS frequency domain spectrum test, tensile test and hot spot temperature test on the windings, the leads and the sleeve according to actual structures in series, obtaining corresponding health indexes, constructing a comprehensive evaluation model by combining a basic evaluation model, and finally correcting the comprehensive evaluation model according to historical record data of a transformer to obtain a final evaluation model, wherein the model fully considers factors such as the load level, the running environment and partial discharge of the transformer, accords with the actual running state of the transformer, and improves the reliability evaluation accuracy of an insulation system. Moreover, the tensile device is adopted to carry out tensile test on the lead wires in the aging box, so that deviation of oil temperature and water content caused by frequent opening of the box cover is avoided, and the accuracy of the model is further improved.
The technical scope of the present invention is not limited to the above description, and those skilled in the art may make various changes and modifications to the above-described embodiments without departing from the technical spirit of the present invention, and these changes and modifications should be included in the scope of the present invention.
Claims (7)
1. The method for evaluating the health state of the insulation system of the power transformer is characterized by comprising the following steps of:
s100, constructing an aging box of an insulation system of a power transformer, and putting a plurality of groups of insulation systems into different aging boxes to perform accelerated aging treatment, wherein the insulation systems comprise winding insulation, lead insulation and sleeve insulation which are connected according to actual structures;
s200, respectively performing FDS frequency domain spectrum test, tensile test and hot spot temperature test on the winding insulation, the lead insulation and the sleeve insulation by using a test instrument at different ageing temperatures and times, and calculating according to each test result to obtain a health index HI1, a health index HI2 and a health index HI3;
s300, constructing a basic evaluation model according to state quantity information of the power transformer, wherein the state quantity information comprises life expectancy, operational years, load level and operation environment;
s400, calculating a comprehensive evaluation model of the insulation system according to the basic evaluation model and combining the health index HI1, the health index HI2 and the health index HI3;
s500, acquiring historical record data of the transformer to be evaluated, and correcting the comprehensive evaluation model to obtain a final evaluation model;
s600, acquiring operation data of the power transformer in real time, and inputting the operation data into the final evaluation model to acquire a health state evaluation result of the insulation system of the power transformer;
wherein the aging box comprises a box body, a high-voltage winding, a low-voltage winding, a high-voltage lead, a low-voltage lead, a high-voltage sleeve, a low-voltage sleeve, an oil storage box, a temperature controller, a dielectric spectrometer, a terminal machine, a multi-path temperature tester, a tension device and a vacuum pump, the high-voltage winding, the low-voltage winding, the high-voltage lead, the low-voltage lead, the high-voltage sleeve and the low-voltage sleeve are sequentially connected, the high-voltage winding, the low-voltage winding, the high-voltage lead and the low-voltage lead are arranged in the box body, the high-voltage sleeve and the low-voltage sleeve are fixedly arranged at the upper part of the box body, insulating oil is filled in the box body, an oil inlet, an oil outlet and an extraction opening are arranged at the side part of the box body, the oil storage tank is characterized in that an inlet of the oil storage tank is communicated with an oil outlet, an outlet of the oil storage tank is connected with an oil inlet through an oil pump, a heating pipe is arranged in the oil storage tank and is electrically connected with a terminal through a temperature controller, a vacuum pump is connected to an extraction opening, one end of a dielectric spectrometer is connected with a high-voltage winding and a low-voltage winding, the other end of the dielectric spectrometer is connected with the terminal, the input end of the multi-channel temperature tester is connected with a high-voltage sleeve, a low-voltage sleeve, a high-voltage lead and a low-voltage lead, the output end of the multi-channel temperature tester is connected with the terminal, the tension device is arranged on the side wall of the tank body and is used for carrying out tensile test on the high-voltage lead and the low-voltage lead so as to obtain the elongation at break of lead insulation.
2. The method for evaluating the health state of an insulation system of a power transformer according to claim 1, wherein the tension device comprises a motor, a first rack, a second rack, a driving gear, a connecting rod assembly and a locking sleeve, the motor is fixedly arranged on the outer wall of the box body, the output end of the motor is connected with an output shaft, the output shaft penetrates through the wall surface of the box body and is connected with the driving gear at the end part of the output shaft, the first rack and the second rack are positioned at two sides of the driving gear and are meshed with the driving gear, the first rack and the second rack are both connected with the inner wall of the box body in a sliding manner through guide rails, the ends of the first rack and the second rack are respectively connected with the locking sleeve through the connecting rod assembly, the high-voltage lead wire and the low-voltage lead wire comprise a lead wire insulator and an inner stranded wire, and the locking sleeve is used for being inserted between the lead wire insulator and the inner stranded wire and clamping the lead wire insulator;
the connecting rod assembly comprises a vertical rod, a cross rod and a chuck rod which are positioned on the same horizontal plane, one end of each vertical rod is fixedly connected with the first rack and the second rack respectively, the other end of each vertical rod is connected with the end part of the cross rod, the other end part of each cross rod is connected with the chuck rod, and the other end part of the chuck rod is fixedly connected with the locking sleeve; pressure sensors are arranged between the upper chuck rod and the lower chuck rod, two ends of each pressure sensor are respectively connected to the two chuck rods through pull ropes, and distance sensors are arranged at corresponding positions between the upper chuck rod and the lower chuck rod.
3. The method for evaluating the health status of an insulation system of a power transformer according to claim 2, wherein the lock sleeve comprises a lock sleeve body, an outer lock sleeve and an inner supporting tube, the side part of the lock sleeve body is fixedly connected with the end part of the clamping head rod, one end part of the inner supporting tube is fixedly arranged at the end part of the lock sleeve body, the other end of the inner supporting tube is used for being inserted between the lead insulator and the inner stranded wire, one end part of the outer lock sleeve extends into the lock sleeve body and is in threaded connection with the lock sleeve body, and the thickness of the inner wall of the other end part of the outer lock sleeve is increased uniformly from outside to inside and is used for clamping the lead insulator.
4. The method for evaluating the health status of an insulation system of a power transformer according to claim 1, wherein the health index HI2 is calculated based on the test result of the tensile test, comprising the steps of:
under different ageing temperatures and ageing times, carrying out tensile tests on lead insulation to obtain a plurality of groups of elongation at break retention rates;
establishing a relation chart of elongation at break retention and aging time at different aging temperatures;
fitting the relation graph by adopting a multi-element nonlinear regression method to obtain a binary nonlinear regression function M about aging temperature and aging time;
the reduction of the elongation at break to 50% is regarded as a failure threshold value of the lead insulation, and the health index h2= (50/M)%.
5. The method for evaluating the health status of an insulation system of a power transformer according to claim 1, wherein the basic evaluation model is calculated as follows:
；
；
in the above-mentioned method, the step of,health index of the evaluation model based on +.>For the initial health index of the device, B is the aging factor, < ->For the current year->For the year of equipment operation, < > for>For the original intended service life, < >>For load correction factor, ++>Is an environmental correction factor.
6. The method for evaluating the health status of an insulation system of a power transformer according to claim 5, wherein the comprehensive evaluation model HIcom of the insulation system is:
in the above, the->Is a constant, its value is equal to->Is related to the size of (a).
7. The method for evaluating the health status of an insulation system of a power transformer according to claim 6, wherein the history data includes equipment operation time T, core grounding current I, transformer appearance level L, sleeve reliability level R, cooling mode, presence or absence of family defect, number of failure defects n, presence or absence of short circuit in a near zone, presence or absence of partial discharge;
the health index H for the final assessment model is:
；
；
in the above-mentioned method, the step of,health index for comprehensive assessment model +.>For the comprehensive correction factor->Is the correction factor of the mth history data.
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