Electric strength prediction method for oil paper insulation of converter transformer

Abstract

The invention relates to the technical field of power system transformers, and discloses a converter transformer oil paper insulation electrical strength prediction method, which comprises the following steps: S01, setting the temperature of a converter transformer oil paper insulation sample, S02, applying voltage to the converter transformer oil paper insulation sample to generate breakdown, S03, collecting breakdown strength data, and S04, determining the electrical strength of the converter transformer oil paper insulation sample. S04, analyzing breakdown strength data, S05, fitting breakdown data according to a quadratic nonlinear regression equation, and S06, predicting the electrical strength of the oil paper insulation of the converter transformer, namely predicting the breakdown strength of the oil paper insulation material under different temperature and harmonic frequency conditions, and determining the electrical strength of the oil paper insulation according to the influence of the temperature and the frequency on the electrical strength of the oil paper insulation. The method can more comprehensively reflect the insulation state under the actual operation condition, and provides a theoretical basis for the evaluation of the insulation performance of the converter transformer equipment in the actual operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system transformer, more particularly to a method for predicting electrical strength of oil-paper insulation of converter transformer. BACKGROUND

[0002] Converter transformer is an indispensable component in power systems, widely used in AC-DC hybrid power transmission systems, especially playing a crucial role in high voltage direct current (HVDC) transmission systems. It can efficiently realize the conversion of electrical energy between AC and DC systems, and has irreplaceable advantages in long-distance power transmission, stable grid operation, improved transmission capacity and reduced transmission loss. However, with the increasing demand for electricity and the continuous expansion of the power grid, converter transformers are facing increasingly severe working environments, especially in HVDC systems, due to the combined use of high voltage direct current and alternating current, the insulation system of the transformer must withstand more complex electrical stress.

[0003] The main insulation material of converter transformer is oil-paper insulation, which plays a crucial role in electrical isolation and thermal management in high voltage direct current transmission systems. However, in this complex working environment, oil-paper insulation is not only exposed to high temperature and voltage stress, but also subjected to high frequency harmonic voltage. These high frequency harmonic voltages have a particularly significant impact on oil-paper insulation, as they can cause local overheating and uneven electric field distribution, leading to insulation material aging, breakdown and even damage. In particular, oil-paper insulation exposed to high frequency harmonic voltage for a long time may undergo thermal degradation under uneven electric field distribution and overheating conditions, which will reduce its insulation strength and affect the safety and reliability of the converter transformer. Therefore, in-depth study of the influence of temperature, harmonic frequency on the breakdown characteristics of oil-paper insulation and the interaction mechanism is of great practical significance for improving the operation safety of converter transformers, prolonging the service life of equipment and optimizing the operation of power systems.

[0004] However, although existing literature has made in-depth exploration of individual factors, the influence of multiple factors such as temperature and harmonic frequency on the breakdown characteristics of oil-paper insulation, especially under high frequency harmonic voltage, is still relatively rare. In addition, existing research mostly focuses on the independent influence of temperature and harmonic frequency, lacking systematic analysis of the synergistic effect of these two factors. In fact, in the actual operation of converter transformers, temperature, harmonic frequency and other electrical stresses usually exist simultaneously, and their interaction may cause the breakdown characteristics of oil-paper insulation to exhibit more complex nonlinear changes. Therefore, how to accurately evaluate the comprehensive influence of these factors and establish the corresponding prediction model has become a major challenge in current research. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the present application provides a method for predicting the electrical strength of oil-paper insulation of a converter transformer to solve the problems existing in the above-mentioned background art.

[0006] The present application provides the following technical solution: a method for predicting the electrical strength of oil-paper insulation of a converter transformer, comprising the following steps:

[0007] Step S01: temperature setting of the oil-paper insulation sample of the converter transformer: the oil-paper insulation sample of the converter transformer is immersed in transformer oil, and the temperature is set to simulate the performance of the oil-paper insulation of the converter transformer, and the heating of the sample is completed by a temperature controller, a strip heater and a thermocouple system;

[0008] Step S02: applying voltage to the oil-paper insulation sample of the converter transformer to cause breakdown: a high-frequency high-voltage power supply is used to apply voltage to the oil-paper insulation sample of the converter transformer, and the power supply is remotely controlled by a computer;

[0009] Step S03: breakdown strength data collection: the breakdown strength data is collected by changing the frequency of the high-frequency high-voltage power supply;

[0010] Step S04: breakdown strength data analysis: the average breakdown strength of the oil-paper insulation sample under different heat aging times, different frequencies and temperature conditions is analyzed according to the collected breakdown strength data;

[0011] Step S05: fitting the breakdown data according to the quadratic nonlinear regression equation: a quadratic nonlinear regression equation is established to fit the breakdown data, and the comprehensive influence of temperature and frequency on the breakdown strength is analyzed;

[0012] Step S06: prediction of the electrical strength of the oil-paper insulation of the converter transformer: the breakdown strength of the oil-paper insulation material under different temperature and frequency conditions is predicted according to the quadratic nonlinear regression equation, and the electrical strength of the oil-paper insulation of the converter transformer is predicted.

[0013] Preferably, in the step S01 of temperature setting of the oil-paper insulation sample of the converter transformer, the oil-paper insulation sample of the converter transformer is immersed in No. 25 transformer oil through a high-frequency breakdown test platform, and the heating of the oil-paper insulation sample of the converter transformer is controlled by a temperature controller, a strip heater and a thermocouple system, and the temperature is set to simulate the performance of the oil-paper insulation of the converter transformer, and the temperature includes 20℃, 40℃, 60℃ and 80℃.

[0014] Preferably, in the step S02 of applying voltage to the oil-paper insulation sample of the converter transformer to cause breakdown, the voltage is applied to the oil-paper insulation sample of the converter transformer to cause breakdown by a high-frequency high-voltage power supply, the frequency range is from 100Hz to 1000Hz, the power supply is remotely controlled by a computer, and a 20MΩ high-voltage resistor is connected with a spherical electrode.

[0015] Preferably, in the step S03 of breakdown strength data collection, the specific content of breakdown strength data collected by changing the frequency of high-frequency high-voltage power supply is as follows:

[0016] The breakdown strength data is collected under different frequencies and temperatures, and the data collection is repeated three times to obtain three sets of harmonic breakdown data, which are represented as S1, S2 and S3, respectively. The three sets of harmonic breakdown data are represented as {S};

[0017] The breakdown strength data of the oil-paper insulation sample of the converter transformer is collected at different frequencies at 20°C, and the collected data set is represented as {f1(S)};

[0018] The breakdown strength data of the oil-paper insulation sample of the converter transformer is collected at different frequencies at 40°C, and the collected data set is represented as {f2(S)};

[0019] The breakdown strength data of the oil-paper insulation sample of the converter transformer is collected at different frequencies at 60°C, and the collected data set is represented as {f3(S)};

[0020] The breakdown strength data of the oil-paper insulation sample of the converter transformer is collected at different frequencies at 80°C, and the collected data set is represented as {f4(S)}.

[0021] Preferably, in the step S04 of breakdown strength data analysis, the specific content of the average breakdown strength of the oil-paper insulation sample under different thermal aging times at different frequencies and temperatures is analyzed according to the collected breakdown strength data as follows:

[0022] When the frequency increases from 100 Hz to 1000 Hz, the breakdown strength decreases from 51.2 kV / mm to 42.4 kV / mm at 20°C, with a decrease of 17.2%;

[0023] When the frequency increases from 100 Hz to 1000 Hz, the breakdown strength decreases from 36.6 kV / mm to 29.1 kV / mm at 80°C, with a decrease of 20.5%;

[0024] When the temperature increases from 20°C to 80°C, the breakdown strength decreases by 28.5% at 100 Hz, and by 31.4% at 1000 Hz;

[0025] The analysis of the breakdown strength data shows that the change of the breakdown strength of the oil-paper insulation sample of the converter transformer due to temperature is higher than the change of the breakdown strength of the oil-paper insulation sample of the converter transformer due to frequency.

[0026] Preferably, in the step S05, the breakdown data is fitted according to a quadratic nonlinear regression equation, and the expression of the quadratic nonlinear regression equation is: Eb = E0 + a1 x T + b1 x f + a2 x T 2 + b2 x f 2 wherein E b represents the fitting output value of the quadratic nonlinear regression equation, E0 represents the theoretical breakdown strength at 0℃ and 0Hz, T represents the test temperature, f represents the test frequency, a1 represents the linear correlation coefficient of the test temperature T, a2 represents the quadratic correlation coefficient of the test temperature T, b1 represents the linear correlation coefficient of the test frequency f, and b2 represents the quadratic correlation coefficient of the test frequency f.

[0027] Preferably, in the step S06 of predicting the electrical strength of the oil-paper insulation of the converter transformer, the specific content of predicting the breakdown strength of the oil-paper insulation material under different temperature and frequency conditions according to the quadratic nonlinear regression equation is: inputting the temperature and frequency data as variables into the nonlinear regression equation, and the fitting output value corresponding to the nonlinear regression equation is the predicted fitting breakdown value, so as to complete the prediction of the electrical strength of the oil-paper insulation of the converter transformer.

[0028] The technical effects and advantages of the present application are as follows:

[0029] The present application predicts the breakdown strength of the oil-paper insulation material under different temperature and harmonic frequency conditions by means of the steps S01 of setting the temperature of the oil-paper insulation sample of the converter transformer, the step S02 of applying voltage to the oil-paper insulation sample of the converter transformer to cause breakdown, the step S03 of collecting the breakdown strength data, the step S04 of analyzing the breakdown strength data, the step S05 of fitting the breakdown data according to the quadratic nonlinear regression equation, and the step S06 of predicting the electrical strength of the oil-paper insulation of the converter transformer, so as to more comprehensively reflect the insulation state under the actual operating conditions according to the influence of temperature and frequency on the electrical strength of the oil-paper insulation.

[0030] The prediction of the breakdown strength of the oil-paper insulation material under different temperature and harmonic frequency conditions provides an effective tool, which not only helps to understand the synergistic effect of temperature and frequency, but also provides a theoretical basis for the insulation performance evaluation of the converter transformer and other devices in actual operation. Future research can further explore the oil-paper insulation performance under more complex electrical stress conditions to improve the operation safety and reliability of the converter transformer. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a flowchart of a method for predicting the electrical strength of the oil-paper insulation of a converter transformer. DETAILED DESCRIPTION

[0032] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. In addition, the forms of the structures described in the following embodiments are only examples, and the electrical strength prediction method of the oil-paper insulation of a converter transformer involved in the present application is not limited to the structures described in the following embodiments. All other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0033] As shown in Figure 1 The present application provides an electrical strength prediction method of oil-paper insulation of a converter transformer, comprising the following steps:

[0034] Step S01: Temperature setting of the oil-paper insulation sample of the converter transformer: The oil-paper insulation sample of the converter transformer is soaked in transformer oil, and the temperature is set to simulate the performance of the oil-paper insulation of the converter transformer. The heating of the sample is completed by a temperature controller, a strip heater and a thermocouple system;

[0035] Step S02: Apply voltage to the oil-paper insulation sample of the converter transformer to cause breakdown: A high-frequency high-voltage power supply is used to apply voltage to the oil-paper insulation sample of the converter transformer, and the power supply is remotely controlled by a computer;

[0036] Step S03: Breakdown strength data collection: The breakdown strength data is collected by changing the frequency of the high-frequency high-voltage power supply;

[0037] Step S04: Breakdown strength data analysis: According to the collected breakdown strength data, the average breakdown strength of the oil-paper insulation sample under different heat aging times, different frequencies and different temperature conditions is analyzed;

[0038] Step S05: Fitting the breakdown data according to the quadratic nonlinear regression equation: A quadratic nonlinear regression equation is established to fit the breakdown data, and the comprehensive influence of temperature and frequency on the breakdown strength is analyzed;

[0039] Step S06: Electrical strength prediction of the oil-paper insulation of the converter transformer: The breakdown strength of the oil-paper insulation material under different temperature and frequency conditions is predicted according to the quadratic nonlinear regression equation, and the electrical strength prediction of the oil-paper insulation of the converter transformer is completed.

[0040] In this embodiment, it needs to be specifically pointed out that in the step S01 of setting the temperature of the converter transformer oil paper insulation sample, through the high-frequency breakdown test platform, the platform can provide a high-precision electrical test environment, in order to prevent surface flashover phenomenon, the converter transformer oil paper insulation sample is immersed in No. 25 transformer oil, which not only provides additional electrical insulation for the sample, but also helps to maintain thermal stability and uniform temperature distribution, thereby avoiding test errors caused by overheating, the heating of the converter transformer oil paper insulation sample is controlled by a temperature controller, a strip heater and a thermocouple system, which accurately heats the sample to the set test temperature, the set temperature simulates the performance of the converter transformer oil paper insulation, and the temperature includes 20℃, 40℃, 60℃ and 80℃.

[0041] In this embodiment, it needs to be specifically pointed out that in the step S02 of applying voltage to the converter transformer oil paper insulation sample to cause breakdown, a high-frequency high-voltage power supply is used to apply voltage to the converter transformer oil paper insulation sample until breakdown occurs, the frequency range is from 100Hz to 1000Hz, covering multiple high-frequency harmonic frequencies, in order to study the comprehensive influence of temperature and harmonic frequency on the breakdown characteristics of oil paper insulation, the power supply is remotely controlled by a computer, and is connected with a spherical electrode through a 20MΩ high-voltage resistor, according to the IEC60156 standard, the experiment adopts a sphere-plate electrode system to ensure that the electric field is uniformly distributed on both sides of the sample, the spherical electrode is in close contact with the plate-shaped electrode, and the application accuracy of the voltage is ensured. In the experiment, the voltage gradually increases at a rate of 1kV / s until breakdown occurs, and breakdown is defined as when the voltage between the two ends of the sample drops by 50 volts, the insulation material breaks down.

[0042] In this embodiment, it needs to be specifically pointed out that in the step S03 of collecting breakdown strength data, the specific content of the breakdown strength data collected by changing the frequency data through the high-frequency high-voltage power supply is as follows:

[0043] Breakdown strength data is collected under different frequency and temperature conditions, and the data collection is repeated three times to obtain three sets of harmonic breakdown data, which are represented as S1, S2 and S3 respectively, and the three sets of harmonic breakdown data are represented as {S};

[0044] The breakdown strength data of the converter transformer oil paper insulation sample at different frequencies is collected at 20℃, and the collected data set is represented as {f1(S)};

[0045] The breakdown strength data of the converter transformer oil paper insulation sample at different frequencies is collected at 40℃, and the collected data set is represented as {f2(S)};

[0046] The breakdown strength data of the converter transformer oil paper insulation sample at different frequencies is collected at 60℃, and the collected data set is represented as {f3(S)};

[0047] The breakdown strength data of the oil-paper insulation sample of the converter transformer at different frequencies is collected at 80℃, and the data collection is represented as {f4(S)}.

[0048] In this embodiment, it needs to be specifically pointed out that in the breakdown strength data analysis of step S04, the specific content of analyzing the average breakdown strength of the oil-paper insulation sample under different heat aging time at different frequency and temperature conditions according to the collected breakdown strength data is as follows:

[0049] When the frequency increases from 100Hz to 1000Hz, the breakdown strength decreases from 51.2kV / mm to 42.4kV / mm at 20℃, and the decrease amplitude is 17.2%;

[0050] When the frequency increases from 100Hz to 1000Hz, the breakdown strength decreases from 36.6kV / mm to 29.1kV / mm at 80℃, and the decrease amplitude is 20.5%;

[0051] When the temperature increases from 20℃ to 80℃, the breakdown strength decreases by 28.5% at 100Hz, and the breakdown strength decreases by 31.4% at 1000Hz;

[0052] The results show that the influence of temperature on the breakdown strength decay of the unaged sample is more significant than the change of frequency, and therefore, the temperature has a more significant influence on the breakdown characteristics of the unaged oil-paper insulation material, and the breakdown strength decrease caused by the temperature change is obviously higher than the influence caused by the frequency change;

[0053] From the data, it can be concluded that although the increase of frequency will cause the breakdown strength to decrease, the influence of temperature is more prominent in the whole experimental range, especially at higher temperature, the breakdown strength of the material decreases significantly, which indicates that the performance of the oil-paper insulation material will be more affected in the high temperature environment, and this phenomenon shows that special attention should be paid to the long-term influence of the high temperature environment on the oil-paper insulation material in the design and application, so as to ensure the stability and safety of the converter transformer under different working conditions.

[0054] In this embodiment, it needs to be specifically pointed out that in step S05, the breakdown data is fitted according to the quadratic nonlinear regression equation, and the expression of the quadratic nonlinear regression equation is: b E = E0+a1×T+b1×f+a2×T 2 +b2×f 2 Wherein, E bThe fitting output value representing a quadratic nonlinear regression equation, E0 is the theoretical breakdown strength at 0°C and 0Hz, T represents the test temperature, f represents the test frequency, a1 represents the first order correlation coefficient of the test temperature T, a2 represents the second order correlation coefficient of the test temperature T, b1 represents the first order correlation coefficient of the test frequency f, and b2 represents the second order correlation coefficient of the test frequency f.

[0055] In the embodiment, it is particularly pointed out that in the step S06 of predicting the electrical strength of the oil-paper insulation of the converter transformer, the specific content of predicting the breakdown strength of the oil-paper insulation material under different temperature and frequency conditions according to the quadratic nonlinear regression equation is that the temperature and frequency data are input into the nonlinear regression equation as variables, and the fitting output value corresponding to the nonlinear regression equation is the predicted fitting breakdown value, thereby completing the prediction of the electrical strength of the oil-paper insulation of the converter transformer.

[0056] The difference between the embodiment and the prior art mainly lies in that the embodiment is provided with the steps S01 of setting the temperature of the oil-paper insulation sample of the converter transformer, the step S02 of applying voltage to the oil-paper insulation sample of the converter transformer to cause breakdown, the step S03 of collecting the breakdown strength data, the step S04 of analyzing the breakdown strength data, the step S05 of fitting the breakdown data according to the quadratic nonlinear regression equation, and the step S06 of predicting the electrical strength of the oil-paper insulation of the converter transformer, thereby predicting the breakdown strength of the oil-paper insulation material under different temperature and harmonic frequency conditions, and comprehensively reflecting the insulation state under the actual operation condition according to the influence of temperature and frequency on the electrical strength of the oil-paper insulation.

[0057] The prediction of the breakdown strength of the oil-paper insulation material under different temperature and harmonic frequency conditions provides an effective tool, the model not only helps to understand the synergistic effect of temperature and frequency, but also provides a theoretical basis for the insulation performance evaluation of the converter transformer and other devices in actual operation, and future research can further explore the oil-paper insulation performance under more complex electrical stress conditions to improve the operation safety and reliability of the converter transformer.

[0058] Finally, the above description is only the preferred embodiment of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0059] The above description is only the specific implementation manner of the present application, but the protection scope of the present application is not limited to this, any modification or replacement within the technical range disclosed by the present application can be easily thought by any person skilled in the art, and shall be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for predicting the electrical strength of oil-paper insulation of a converter transformer, characterized by: The following steps are involved: Step S01: Setting the temperature of the converter transformer oil-paper insulation sample: The converter transformer oil-paper insulation sample is immersed in transformer oil, and the temperature is set to simulate the converter transformer oil-paper insulation performance. The sample is heated by a temperature controller, a strip heater, and a thermocouple system. Step S02: applying voltage to the converter transformer oil-paper insulation sample to cause breakdown: applying voltage to the converter transformer oil-paper insulation sample via a high-frequency high-voltage power supply, the power supply being remotely controlled by a computer; Step S03: breakdown strength data collection: collecting breakdown strength data by changing the frequency of a high-frequency high-voltage power supply; Step S04: breakdown strength data analysis: analyzing the average breakdown strength of oil-paper insulation samples after different thermal aging times under different frequency and temperature conditions based on the collected breakdown strength data; Step S05: Fitting the breakdown data according to the quadratic nonlinear regression equation: Establishing a quadratic nonlinear regression equation to fit the breakdown data, and analyzing the comprehensive effects of temperature and frequency on the breakdown strength; Step S06: Prediction of the electrical strength of the oil-paper insulation of the converter transformer: The breakdown strength of the oil-paper insulation material under different temperature and frequency conditions is predicted based on the quadratic nonlinear regression equation to complete the electrical strength prediction of the oil-paper insulation of the converter transformer.

2. The method for predicting the electrical strength of oil-paper insulation of a converter transformer according to claim 1, wherein: In step S01, the temperature of the converter transformer oil-paper insulation sample is set. The converter transformer oil-paper insulation sample is immersed in No. 25 transformer oil through a high-frequency breakdown test platform. The heating of the converter transformer oil-paper insulation sample is controlled by a temperature controller, a strip heater and a thermocouple system. The set temperature simulates the converter transformer oil-paper insulation performance. The temperatures include: 20°C, 40°C, 60°C and 80°C.

3. The method for predicting the electrical strength of oil-paper insulation of a converter transformer according to claim 1, wherein: In step S02, voltage is applied to the oil-paper insulation sample of the converter transformer to cause breakdown. Voltage is applied to the oil-paper insulation sample of the converter transformer until breakdown occurs through a high-frequency high-voltage power supply, with a frequency range from 100 Hz to 1000 Hz. The power supply is remotely controlled by a computer and connected to the spherical electrode through a 20 MΩ high-voltage resistor.

4. The method for predicting the electrical strength of oil-paper insulation of a converter transformer according to claim 1, wherein: In the step S03 of collecting breakdown strength data, the specific contents of collecting breakdown strength data by changing the frequency of the high-frequency high-voltage power supply are as follows: The breakdown strength data is collected under different frequency and temperature conditions. The data collection is repeated three times to obtain three sets of harmonic breakdown data, which are represented as: S1, S2 and S3 respectively. The three sets of harmonic breakdown data are represented as {S}; The breakdown strength data of the converter transformer oil-paper insulation sample at different frequencies are collected at 20℃, and the collected data set is represented as {f1(S)}; The breakdown strength data of the converter transformer oil-paper insulation sample at different frequencies are collected at 40℃, and the collected data set is represented as {f2(S)}; The breakdown strength data of the converter transformer oil-paper insulation sample at different frequencies are collected at 60℃, and the collected data set is represented as {f3(S)}; The breakdown strength data of the converter transformer oil-paper insulation sample at different frequencies are collected at 80°C, and the collected data set is represented as {f4(S)}.

5. The method for predicting the electrical strength of oil-paper insulation of a converter transformer according to claim 1, wherein: In the breakdown strength data analysis step S04, the specific contents of analyzing the average breakdown strength of the oil-paper insulation samples after different heat aging times under different frequency and temperature conditions based on the collected breakdown strength data are as follows: When the frequency increases from 100 Hz to 1000 Hz, at 20°C, the breakdown strength decreases from 51.2 kV / mm to 42.4 kV / mm, a decrease of 17.2%. When the frequency increases from 100 Hz to 1000 Hz, at 80°C, the breakdown strength decreases from 36.6 kV / mm to 29.1 kV / mm, a decrease of 20.5%. When the temperature increases from 20°C to 80°C, the breakdown strength decreases by 28.5% at 100 Hz and by 31.4% at 1000 Hz. The analysis of breakdown strength data shows that the effect of temperature on breakdown strength degradation of converter transformer oil-paper insulation samples is greater than the effect of frequency on breakdown strength degradation of converter transformer oil-paper insulation samples.

6. The method for predicting the electrical strength of oil-paper insulation of a converter transformer according to claim 1, wherein: In step S05, the breakdown data is fitted according to a quadratic nonlinear regression equation, and the expression of the quadratic nonlinear regression equation is: b =E0+a1×T+b1×f+a2×T 2 +b2×f 2 , where E b represents the fitting output value of the quadratic nonlinear regression equation, E0 is the theoretical breakdown strength at 0°C and 0 Hz, T represents the test temperature, f represents the test frequency, a1 represents the first-order correlation coefficient of the test temperature T, a2 represents the second-order correlation coefficient of the test temperature T, b1 represents the first-order correlation coefficient of the test frequency f, and b2 represents the second-order correlation coefficient of the test frequency f.

7. The method for predicting the electrical strength of oil-paper insulation of a converter transformer according to claim 1, wherein: In the step S06 of predicting the electrical strength of the oil-paper insulation of the converter transformer, the specific content of predicting the breakdown strength of the oil-paper insulation material under different temperature and frequency conditions based on the quadratic nonlinear regression equation is as follows: temperature and frequency data are input into the nonlinear regression equation as variables, and the fitting output value corresponding to the nonlinear regression equation is the predicted fitting breakdown value, thereby completing the electrical strength prediction of the oil-paper insulation of the converter transformer.

Images