Method for calculating static pressure generated by arc discharge in transformer oil tank

Abstract

The invention discloses a method for calculating static pressure generated by arc discharge in a transformer oil tank, and the method comprises the steps: obtaining an expansion coefficient c of the transformer oil tank; electric arc time-varying power P (t) and energy W (t) of electric arc discharge in the transformer oil tank are obtained through calculation; the arc discharge product temperature T of arc discharge in the transformer oil tank is obtained; a gas space V0 existing in the transformer oil tank is measured, and the amount Vg of gas dissolved in oil is calculated according to the solubility kh of characteristic gas generated by the electric arc in the oil; and calculating static pressure p generated by arc discharge in the transformer oil tank according to a static pressure calculation formula.

Description

Technical Field

[0001] The invention relates to the technical field of transformer detection, in particular to a method for calculating static pressure generated by arc discharge in a transformer oil tank. Background Art

[0002] When a short circuit occurs in the transformer tank, an arc discharge will occur, causing the transformer oil to decompose and produce gas, which will increase the pressure in the tank, further causing the tank to rupture or even explode and catch fire. The pressure in the tank is divided into dynamic pressure and static pressure. Existing studies have shown that the main reason for the damage to the tank is the increase in static pressure caused by the accumulation of gas generated by the arc in the tank. Therefore, it is necessary to calculate the static pressure for the explosion-proof design of the transformer tank. The existing technology for calculating the static pressure in the tank has a large deviation, and does not take into account the existence of gas space in the tank and the dissolution of gas generated by discharge in the oil.

[0003] The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0004] In view of the shortcomings or defects of the above-mentioned prior art, a method for calculating the static pressure generated by arc discharge in a transformer oil tank is provided, which can effectively and accurately calculate the static pressure of arc discharge in the transformer oil tank, reduce the cost of discharge experiments, and provide support for the explosion-proof design of the transformer oil tank.

[0005] The purpose of the present invention is achieved through the following technical solutions.

[0006] A method for calculating the static pressure generated by arc discharge in a transformer oil tank includes:

[0007] Obtain the expansion coefficient c of the transformer tank;

[0008] The arc time-varying power P(t) of the arc discharge in the transformer oil tank is calculated and integrated to obtain the energy W(t). Based on the relationship between arc energy and gas production, that is, the discharge gas production is proportional to the arc energy, the arc discharge gas production V in the transformer oil is obtained. g ;

[0009] Obtaining the arc discharge product temperature T of the arc discharge in the transformer oil tank;

[0010] Measure the gas space V0 in the transformer oil tank, and the solubility k of the characteristic gas generated by the arc in the oil h , calculate the amount of dissolved gas in oil V g ;

[0011] According to the static pressure calculation formula, the static pressure p generated by arc discharge in the transformer tank is calculated. p: static pressure of liquid and gas in transformer oil tank, unit is bar, c: oil tank expansion coefficient, unit is L / bar, V g : discharge gas production, which is the volume under normal pressure, the unit is L, T: arc discharge product temperature, T0: ambient temperature, V0: gas space in the transformer tank before discharge, the unit is L, k h : Henry's constant, which characterizes the volume of gas generated by discharge dissolved in unit volume of oil at atmospheric pressure, with the unit being L.

[0012] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the expansion coefficient c of the transformer oil tank is obtained by an explicit dynamics method or a strain measurement method, wherein the explicit dynamics method is used to calculate the stress, strain or deformation amount when pressure exists in the transformer oil tank to obtain the expansion coefficient c of the transformer oil tank, and the explicit dynamics calculation result is verified by strain measurement and displacement measurement of the deformation amount.

[0013] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the arc time-varying power P(t) and energy W(t) are calculated by measuring the measured data of arc voltage u(t) and current i(t) through the arc measurement, or according to the estimation method of short-circuit arc voltage, wherein the arc measurement experiment measures the current and voltage of the arc discharge through a current sensor and a voltage sensor, or deduces the arc voltage through recorded data, or estimates the arc voltage based on transformer disassembly analysis combined with an arc voltage estimation method, and then calculates the waveform of the arc power and energy varying with time based on the arc voltage and current.

[0014] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the Rogowski coil measures the arc discharge current, and the high-voltage differential probe measures the arc discharge voltage.

[0015] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the arc voltage is estimated by using the Ayrton model, the Cassie arc voltage model or the Mayr arc voltage model.

[0016] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the arc discharge product temperature T is measured based on a transient high temperature measurement experiment or is deduced through an ideal gas state equation.

[0017] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, gas is injected into the oil tank through a gas injection experiment in the oil tank, and the gas space V0 is calculated by counting the gas injection amount and its corresponding static pressure in the oil tank. An air bag diaphragm is set at the gas injection port to prevent the injected gas from affecting the gas content in the oil.

[0018] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the amount of dissolved gas in the oil V g The relationship between it and the corresponding static pressure p in the fuel tank is a linear relationship.

[0019] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the amount of dissolved gas in the oil V g The linear relationship between the static pressure p in the corresponding oil tank is: V0′=V0+k h , V′0 is the equivalent reserved gas volume including dissolved gas.

[0020] In the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the static pressure indicates that the pressure is evenly distributed in the oil tank, and the static pressure has a time-varying characteristic that changes with time. The changing trend of the static pressure in the oil tank with the gas production and the equivalent reserved gas volume V′0 is plotted and displayed in a three-dimensional contour map.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention considers the existence of gas space in the oil tank and the dissolution of gas generated by discharge in the oil, analyzes and calculates the static pressure change trend under the influence of multiple factors, and analyzes the change law of static pressure gradient under the influence of multiple factors. The gradient reflects the strong and weak relationship of the influence of multiple factors on static pressure. The static pressure of arc discharge in the transformer oil tank can be calculated more effectively and accurately, which can reduce the cost of discharge experiments and provide support for the explosion-proof design of transformer oil tanks.

[0023] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to achieve the extent that those skilled in the art can implement it according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0025] In the attached picture:

[0026] Figure 1It is a flow chart of a method for calculating the static pressure generated by arc discharge in a transformer tank;

[0027] Figure 2 is the simulation and experimental measurement results of the tank strain;

[0028] Figure 3 It is the power and energy waveform calculated based on the arc voltage and current in the experiment;

[0029] Figure 4 It is the result of experimental measurements of the existence of gas space within the tank;

[0030] FIG5(a) is a comparison of the calculation results of the calculation method proposed by the present invention and the existing method when the temperature of the discharge product is cooled to room temperature;

[0031] FIG5( b ) is a comparison of the calculation results of the calculation method proposed by the present invention and the existing method when considering the temperature change of the discharge product during the arc burning process;

[0032] Figure 6 It is a three-dimensional contour map of static pressure change trends under the influence of various factors;

[0033] Figure 7 It is a graph showing the change in static pressure gradient under the influence of multiple factors.

[0034] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0036] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0037] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0038] For a better understanding, Figures 1 to 7 As shown, a method for calculating the static pressure generated by arc discharge in a transformer oil tank includes:

[0039] Obtain the expansion coefficient c of the transformer tank;

[0040] The arc time-varying power P(t) of the arc discharge in the transformer oil tank is calculated and integrated to obtain the energy W(t). Based on the relationship between arc energy and gas production, that is, the discharge gas production is proportional to the arc energy, the arc discharge gas production V in the transformer oil is obtained. g ;

[0041] Obtaining the arc discharge product temperature T of the arc discharge in the transformer oil tank;

[0042] Measure the gas space V0 in the transformer oil tank, and the solubility k of the characteristic gas generated by the arc in the oil h , calculate the amount of dissolved gas in oil V g ;

[0043] According to the static pressure calculation formula, the static pressure p generated by arc discharge in the transformer tank is calculated. p: static pressure of liquid and gas in transformer oil tank, unit is bar, c: oil tank expansion coefficient, unit is L / bar, V g : discharge gas production, which is the volume under normal pressure, the unit is L, T: arc discharge product temperature, T0: ambient temperature, V0: gas space in the transformer tank before discharge, the unit is L, k h : Henry's constant, which characterizes the volume of gas generated by discharge dissolved in unit volume of oil at atmospheric pressure, with the unit being L.

[0044] In a preferred embodiment of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the expansion coefficient c of the transformer oil tank is obtained by an explicit dynamics method or a strain measurement method, wherein the explicit dynamics method is used to calculate the stress, strain or deformation amount when pressure exists in the transformer oil tank to obtain the expansion coefficient c of the transformer oil tank, and the explicit dynamics calculation results are verified by strain measurement and displacement measurement of the deformation amount.

[0045] In the preferred embodiment of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the measured data of arc voltage u(t) and current i(t) are measured by the arc, or the time-varying power P(t) of the arc is calculated according to the estimation method of short-circuit arc voltage and the energy W(t) is obtained by integration, wherein the arc measurement experiment measures the current and voltage of the arc discharge by current sensor and voltage sensor, or deduce the arc voltage by recording data, or estimate the arc voltage according to transformer disassembly analysis combined with arc voltage estimation method, and then calculates the waveform of arc power and energy changing with time according to arc voltage and current. Based on the relationship between arc energy and gas production, that is, the discharge gas production is proportional to the arc energy, the arc discharge gas production V in transformer oil is obtained. g .

[0046] In a preferred implementation of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the Rogowski coil measures the arc discharge current, and the high-voltage differential probe measures the arc discharge voltage.

[0047] In a preferred implementation of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the arc voltage is estimated using an Ayrton model, a Cassie arc voltage model or a Mayr arc voltage model.

[0048] In a preferred embodiment of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the arc discharge product temperature T is measured based on a transient high temperature measurement experiment or is deduced through an ideal gas state equation.

[0049] In a preferred embodiment of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, gas is injected into the oil tank through a gas injection experiment in the oil tank, and the gas space V0 is calculated by counting the gas injection amount and its corresponding static pressure in the oil tank, and an airbag diaphragm is set at the gas injection port to prevent the injected gas from affecting the gas content in the oil.

[0050] In the preferred embodiment of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the amount of dissolved gas in the oil V g The relationship between it and the corresponding static pressure p in the fuel tank is a linear relationship.

[0051] In the preferred embodiment of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the amount of dissolved gas in the oil V g The linear relationship between the static pressure p in the corresponding oil tank is: V′0=V0+k h , V′0 is the equivalent reserved gas volume including dissolved gas.

[0052] In a preferred implementation of the method for calculating the static pressure generated by arc discharge in the transformer oil tank, the static pressure indicates that the pressure is evenly distributed in the oil tank, and the static pressure has a time-varying characteristic that changes with time. The changing trend of the static pressure in the oil tank with the gas production and the equivalent reserved gas volume V′0 is plotted and displayed in a three-dimensional contour map.

[0053] In one embodiment, a method for calculating static pressure generated by arc discharge in a transformer tank includes:

[0054] Obtain the expansion coefficient c of the oil tank by explicit dynamics method or strain measurement method;

[0055] The time-varying arc power is calculated by the measured data of arc voltage and current, or by the estimation method of short-circuit arc voltage, and the energy W(t) is obtained by integration. Based on the relationship between arc energy and gas production, that is, the discharge gas production is proportional to the arc energy, the arc discharge gas production V in transformer oil is obtained. g ;

[0056] The arc discharge product temperature T is derived from the ideal gas state equation or measured experimentally based on transient high temperature measurement technology.

[0057] Through the gas injection experiment in the oil tank, the gas space existing in the oil tank is measured, and the amount of dissolved gas in the oil is calculated based on the solubility of the characteristic gas generated by the arc in the oil.

[0058] Substituting the above parameters into the static pressure calculation formula proposed in the present invention, the time variation law of the static pressure generated by the arc discharge in the transformer oil tank is calculated.

[0059] In a preferred embodiment of the method, it is necessary to obtain the expansion coefficient c of the oil tank in the calculation object, which is used to quantitatively characterize the flexibility of the oil tank. The acquisition method includes but is not limited to: using an explicit dynamics method to calculate parameters such as stress, strain, and deformation when there is pressure in the oil tank, and verifying the explicit dynamics calculation results by strain measurement, displacement measurement of deformation, etc.

[0060] In a preferred embodiment of the method, in experimental measurement, the current and voltage of the arc discharge can be measured by a current sensor and a voltage sensor. However, in an arc fault that occurs during actual operation of the transformer, the arc voltage cannot be accurately obtained. In this case, the arc voltage needs to be deduced through the waveform recording data, or the arc voltage needs to be estimated based on the transformer disassembly analysis and arc voltage estimation method. Subsequently, the waveform of the arc power and energy changing with time is calculated based on the arc voltage and current.

[0061] In a preferred embodiment of the method, a small amount of gas may be stored in the transformer tank, or a pressure protection measure of a buffer air bag is expected to exist. The gas space in the transformer tank needs to be considered, and when calculating the static pressure, the accurate value of the gas space V0 needs to be obtained.

[0062] In a preferred embodiment of the method, in actual measurement, V'0 can be calculated by injecting gas into the oil tank and counting the amount of gas injected and its corresponding static pressure in the oil tank. In order to prevent the injected gas from affecting the gas content in the oil, an airbag diaphragm can be set at the gas injection port to prevent the gas from dissolving in the oil. At this time, V0 is obtained.

[0063] In a preferred embodiment of the method, the volume k of dissolved gas per unit pressure in the transformer tank is calculated based on the characteristic gas composition and content generated by arc discharge in the tank and the solubility of the characteristic gas in the oil. h .

[0064] In the preferred implementation of the method, based on the above parameters, the corresponding static pressure waveform in the transformer tank is calculated according to the arc energy waveform. It is worth noting that static pressure does not mean that the pressure is constant, but that the pressure is evenly distributed in the tank. The static pressure will also change with time and has a time-varying characteristic.

[0065] In a preferred implementation of the method, in order to more intuitively demonstrate the differences in the degree of influence of various factors on the static pressure in the oil tank, the changing trend of the static pressure in the oil tank with the gas production and the equivalent reserved gas volume is calculated and plotted, and displayed in a three-dimensional contour map.

[0066] In a preferred embodiment of the method, in order to further obtain the strength relationship of the influence of different factors on the static pressure in the fuel tank, a gradient analysis method is used to analyze the strong and weak coupling mechanism of the static pressure in the fuel tank.

[0067] In this embodiment, the explicit dynamic finite element calculation method is first used to establish a three-dimensional model of the experimental oil tank, and pressure is applied to the inner wall to calculate the change in internal volume under different pressures. Two sampling points are set at the side wall flange and the top to analyze the stress change. Strain gauges and strain meters are used to carry out strain measurement experiments. Gas is filled into the oil tank to subject its inner wall to pressure and generate strain. Strain gauges are pasted at the corresponding positions of the two sampling points in the simulation, and the strain values ​​of the oil tank are measured and compared with the simulation values. The accuracy of the simulation results is verified. The experimental and simulation comparison results are shown in the figure. Figure 2 As shown. The fuel tank expansion coefficient is defined as the change in the volume of the fuel tank under unit pressure. The fuel tank expansion coefficient is about 0.0042L / bar.

[0068] In this embodiment, the arc discharge current is measured by a Rogowski coil, and the arc discharge voltage is measured by a high-voltage differential probe. The power and energy waveforms of the arc are calculated according to the following formula.

[0069] P(t)=u(t)i(t)(1)

[0070] W(t)=∫P(t)dt(2)

[0071] Where: u(t) is the arc voltage, i(t) is the arc current, P(t) is the arc power, and W(t) is the arc energy

[0072] When the arc voltage needs to be estimated, the Ayrton model (as shown below), the Cassie arc voltage model or the Mayr arc voltage model can generally be used to estimate the arc voltage, and further obtain the arc power and energy waveform.

[0073]

[0074] Among them, l is the arc length, a, b, c, d are model parameters

[0075] In this embodiment, when the oil tank is almost full of oil, there are still a few micro air gaps in the oil tank. In order to calculate the volume occupied by the gas in the micro air gaps, gas is injected into the oil tank and the gas injection volume V is calculated. g And its corresponding static pressure p in the oil tank, the gas space in the oil tank can be calculated according to the following formula. Since the airbag diaphragm is not used in this experiment, that is, the injected gas will be partially dissolved in the oil, the equivalent reserved gas volume V′0 obtained by fitting includes the dissolved gas: Figure 4 The slope of the fitting line is V′0=0.275L

[0076]

[0077] In this embodiment, the gas composition and content generated by the arc is about 70% H2, 15% CH4, 10% C2H2, and 5% others. According to the solubility of the above characteristic gases in oil, it is calculated that the amount of dissolved gas in the transformer oil in the oil tank is about 200mL under normal pressure.

[0078] In this embodiment, the calculation formula of the static pressure in the oil tank is as follows:

[0079]

[0080] Where, p: static pressure of liquid and gas in the tank, unit bar = 100kPa = 1atm. c: expansion coefficient of the tank, unit L / bar. V g: Discharge gas production (volume under normal pressure), unit is L. T: Average temperature of arc discharge products. T0: Ambient temperature, usually room temperature. V0: The volume of gas at normal pressure reserved in the experimental chamber before discharge, or the volume of the gas bag, unit is L. k h : Henry's constant, which characterizes the volume of gas generated by discharge dissolved in unit volume of oil under atmospheric pressure, with the unit being L.

[0081] In the above formula, V0, which represents the reserved gas volume, and k, which represents the amount of dissolved gas in the discharge h In mathematical form, it has a symmetrical position, that is, the effect of gas dissolution in oil and the gas space reserved in the oil tank on the discharge static pressure is equivalent. In order to simplify the study, V0′=V0+k h , which is called the equivalent reserved gas volume in the fuel tank.

[0082] Substituting the above parameters into the static pressure calculation formula proposed by the present invention, the static pressure generated by arc discharge in the transformer tank is calculated to change with time. The calculation results are compared with the existing calculation method, and the results are shown in Figure 5 (a) and Figure 5 (b). The calculation results proposed by the present invention are significantly better than the existing calculation method.

[0083] In this embodiment, in order to more intuitively demonstrate the differences in the degree of influence of the three factors of fuel tank expansion coefficient, gas production, and equivalent reserved gas volume on the static pressure in the fuel tank, under different fuel tank expansion coefficient conditions, the changing trends of the static pressure in the fuel tank with gas production and equivalent reserved gas volume are calculated and plotted, and displayed in a three-dimensional contour map.

[0084] In this embodiment, in order to further obtain the strength relationship of the influence of the three factors of fuel tank expansion coefficient, gas production, and equivalent reserved gas volume on the static pressure in the fuel tank, the gradient analysis method is used to solve the gradient of the static pressure calculation expression. Under different independent variable ranges, the gradient of the static pressure is solved, and the strength and weakness coupling mechanism of the above three factors on the static pressure in the fuel tank is characterized.

[0085] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0086] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for calculating the static pressure generated by arc discharge in a transformer oil tank, characterized in that: These include, Obtain the expansion coefficient c of the transformer tank; The arc time-varying power P(t) of the arc discharge in the transformer oil tank is calculated and integrated to obtain the energy W(t). Based on the relationship between arc energy and gas production, that is, the discharge gas production is proportional to the arc energy, the arc discharge gas production V in the transformer oil is obtained. g ; Obtaining the arc discharge product temperature T of the arc discharge in the transformer oil tank; Measure the gas space V0 in the transformer oil tank, and the solubility k of the characteristic gas generated by the arc in the oil h , calculate the amount of dissolved gas in oil V g ; According to the static pressure calculation formula, the static pressure p generated by arc discharge in the transformer tank is calculated. p: static pressure of liquid and gas in transformer oil tank, unit is bar, c: oil tank expansion coefficient, unit is L / bar, V g : discharge gas production, which is the volume under normal pressure, the unit is L, T: arc discharge product temperature, T0: ambient temperature, V0: gas space in the transformer tank before discharge, the unit is L, k h : Henry's constant, which characterizes the volume of gas generated by discharge dissolved in unit volume of oil at atmospheric pressure, with the unit being L.

2. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 1, characterized in that: Preferably, the expansion coefficient c of the transformer oil tank is obtained by an explicit dynamics method or a strain measurement method, wherein the explicit dynamics method is used to calculate the stress, strain or deformation amount when pressure exists in the transformer oil tank to obtain the expansion coefficient c of the transformer oil tank, and the explicit dynamics calculation result is verified by strain measurement and displacement measurement of the deformation amount.

3. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 1, characterized in that: The measured data of arc voltage u(t) and current i(t) are measured by arc measurement, or the time-varying arc power P(t) is calculated according to the estimation method of short-circuit arc voltage and the energy W(t) is obtained by integration. In the arc measurement experiment, the current and voltage of arc discharge are measured by current sensor and voltage sensor, or the arc voltage is deduced by waveform recording data, or the arc voltage is estimated according to the transformer disassembly analysis combined with the arc voltage estimation method, and then the waveform of arc power and energy varying with time is calculated according to the arc voltage and current; based on the relationship between arc energy and gas production, that is, the discharge gas production is proportional to the arc energy, the arc discharge gas production V in transformer oil is obtained. g .

4. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 3, characterized in that: The arc discharge current was measured by Rogowski coil and the arc discharge voltage was measured by high voltage differential probe.

5. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 3, characterized in that: The arc voltage is estimated using the Ayrton model, the Cassie arc voltage model or the Mayr arc voltage model.

6. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 1, characterized in that: The arc discharge product temperature T is measured based on transient high temperature measurement experiments or is deduced through the ideal gas state equation.

7. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 1, characterized in that: Gas is injected into the oil tank through the gas injection experiment, and the gas space V0 is calculated by counting the gas injection volume and its corresponding static pressure in the oil tank. An air bag diaphragm is set at the gas injection port to prevent the injected gas from affecting the gas content in the oil.

8. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 1, characterized in that: The amount of gas dissolved in oil V g The relationship between it and the corresponding static pressure p in the fuel tank is a linear relationship.

9. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 1, characterized in that: The amount of gas dissolved in oil V g The linear relationship between the static pressure p in the corresponding oil tank is: V0′=V0+k h , V′0 is the equivalent reserved gas volume including dissolved gas.

10. The method for calculating the static pressure generated by arc discharge in a transformer oil tank according to claim 9, characterized in that: Static pressure means that the pressure is evenly distributed in the oil tank. Static pressure has a time-varying characteristic that changes with time. The changing trend of static pressure in the oil tank with gas production and equivalent reserved gas volume V′0 is plotted and displayed in a three-dimensional contour map.

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