Simulation Method and System for Arc Fault Pressure Inside Oil-Immersed Transformer Tank

Abstract

This invention discloses a method and system for simulating the pressure of an arc fault inside an oil-immersed transformer tank, belonging to the field of power equipment safety protection technology. The method includes: establishing a geometric simulation model of the oil-immersed transformer tank and dividing the geometric simulation model into a network model; establishing a gas compression model based on the network model, and establishing a gas generation model by combining the relationship between gas production and arc energy, and the gas content in the oil during the operation of the oil-immersed transformer; establishing an energy transfer model based on the gas generation model and the relationship between arc energy and arc discharge time; and obtaining a pressure change cloud map inside the tank based on the energy transfer model and a transient pressure acoustic model. This invention overcomes the technical problem of existing technologies that struggle to improve the efficiency of pressure simulation while ensuring its accuracy.

Description

Technical Field

[0001] This invention relates to the field of power equipment safety protection technology, specifically to a method and system for simulating the pressure of arc faults inside the oil tank of an oil-immersed transformer. Background Technology

[0002] As a key piece of equipment in the power system, the safe and stable operation of oil-immersed transformers is crucial to the power grid. When a fault occurs inside the transformer, it goes through stages such as the breakdown of insulation materials to generate an electric arc, the conversion of energy between the arc and the oil, a sudden increase in local pressure, the propagation of pressure waves leading to tank rupture, and spontaneous combustion of flammable mixture. Due to their large size and complex structure, oil-immersed transformers are prone to failure to quickly transmit pressure to the main body when a fault occurs, which can easily lead to the tank bursting due to the failure of the main body pressure relief valve to activate. Therefore, to improve the safety of oil-immersed transformers, it is crucial to simulate and analyze the arc discharge pressure to promptly detect internal transformer faults. Existing technologies mainly use fluid dynamics simulation models for simulation, such as the simulation modeling method for arc discharge pressure in transformer oil (patent publication number CN116738875A), which includes the following steps: Step S1: Collect the dimensions of the transformer tank, perform 3D modeling of the tank based on the dimensions, and mesh the model; Step S2: Select a fluid dynamics calculation model; Step S3: Input the arc energy curve into the fluid dynamics calculation model; Step S4: Simulate the vaporization and decomposition process of transformer oil under the action of the arc using a mass transfer model; Step S5: Calculate the deformation of the tank wall caused by the impact and the pressure field distribution inside the tank by setting the appropriate fluid-structure interaction algorithm based on the tank material. The aforementioned fluid dynamics simulation model involves complex chemical reactions, which improves the accuracy of pressure simulation, but it suffers from a large computational load. When faced with some urgent fault situations, the simulation calculation speed will lag behind the fault evolution process, making it difficult to meet the real-time early warning requirements. Therefore, how to improve the efficiency of pressure simulation while ensuring its accuracy is a technical challenge that needs to be overcome by existing technologies. Summary of the Invention

[0003] To address the technical challenge of simultaneously ensuring accuracy and efficiency in pressure simulation using existing technologies, this invention provides a method and system for simulating arc faults inside the tank of an oil-immersed transformer. By employing a gas compression model and considering the relationship between gas generation and arc energy, as well as the gas content in the oil during transformer operation, a gas generation model is established. Based on this model and the relationship between arc energy and arc discharge time, an energy transfer model capable of being processed by a transient pressure acoustic model is created. The arc fault process is accurately simulated by examining key aspects of gas generation and energy transfer. Furthermore, the low computational complexity of the transient pressure acoustic model allows for the acquisition of pressure change contour maps within the tank. This overcomes the technical difficulty of simultaneously ensuring accuracy and efficiency in pressure simulation using existing technologies.

[0004] To address the aforementioned technical problems, this invention provides a method for simulating the pressure of an arc fault inside the oil tank of an oil-immersed transformer, comprising the following steps:

[0005] A geometric simulation model of the oil tank of an oil-immersed transformer is established, and a network model is obtained by dividing the geometric simulation model into a network.

[0006] A gas compression model is established based on a network model, and a gas production model is established by combining the relationship between gas production and arc energy and the gas content in oil during the operation of an oil-immersed transformer.

[0007] An energy transfer model is established based on the gas generation model and the relationship between arc energy and arc discharge time. Based on the energy transfer model and the transient pressure acoustic model, a pressure change cloud map inside the oil tank is obtained.

[0008] By adopting the above technical solution, the present invention has the following advantages:

[0009] By employing a gas compression model, combining the relationship between gas generation and arc energy, and the gas content in the oil during the operation of an oil-immersed transformer, a gas generation model is established. Based on the gas generation model and the relationship between arc energy and arc discharge time, an energy transfer model that can be processed by a transient pressure acoustic model is established. The arc fault process is accurately simulated from the key stages of gas generation and energy transfer. Furthermore, the low computational complexity of the transient pressure acoustic model is utilized to obtain pressure change contour maps inside the oil tank. This overcomes the technical challenge of existing technologies in simultaneously ensuring the accuracy and efficiency of pressure simulation.

[0010] By accurately and quickly acquiring pressure change cloud maps, high-risk areas can be located rapidly, enabling timely responses and improving the safety of oil-immersed transformers.

[0011] Preferably, the establishment of the geometric simulation model of the oil-immersed transformer tank includes:

[0012] Establish a benchmark simulation model that includes the outer shell of the fuel tank and the electromagnetic module inside the fuel tank. Based on any module inside the fuel tank other than the electromagnetic module, obtain several comparative simulation models with the benchmark simulation model.

[0013] Under the same boundary conditions, obtain the absolute difference between the physical quantities characterizing pressure in the benchmark simulation model and the comparative simulation model;

[0014] The geometric simulation model is obtained by performing a union operation between the comparative simulation model with an absolute difference greater than a preset difference and the benchmark simulation model.

[0015] In this scheme, due to the complex internal structure of oil-immersed transformers, which includes structures with relatively minor impact on arc fault pressure, a baseline simulation model is first constructed. Then, several comparative simulation models are obtained by sequentially adding structures. Under the same boundary conditions, the absolute differences between the physical quantities representing pressure characteristics in the baseline and comparative simulation models are obtained. Comparative simulation models with absolute differences greater than a preset value are then merged with the baseline simulation model to obtain the geometric simulation model. This approach ensures the accuracy of subsequent simulations while reducing the complexity of the geometric simulation model. This solves the technical problem of low computational efficiency caused by the complex internal structure of oil-immersed transformers and the redundancy of non-critical structures in arc fault pressure simulation.

[0016] Preferably, the step of establishing a gas compression model based on a network model, and establishing a gas production model by combining the relationship between gas production and arc energy, and the gas content in the oil during the operation of the oil-immersed transformer, includes:

[0017] The network model was imported into the simulation software, and a gas compression model was established by combining the relationship between the tank expansion coefficient and the tank pressure.

[0018] Based on the law of conservation of mass, and combined with the relationship between gas production and arc energy, the consumption function of oil volume consumed during arc discharge is obtained.

[0019] Based on the gas compression model, a gas production model is obtained by combining the gas content in oil with the consumption function.

[0020] Preferably, the establishment of the energy transfer model based on the gas generation model and the relationship between arc energy and arc discharge time includes:

[0021] The pressure of the gas inside the bubble during the arc discharge process is obtained based on the gas generation model, and the pressure difference between the gas inside the bubble and the oil interface is obtained based on the pressure of the gas inside the bubble.

[0022] An energy transfer model is obtained based on the relationship between pressure difference, arc energy, and arc discharge time.

[0023] Preferably, obtaining the pressure of the gas inside the bubble during the arc discharge process based on the gas generation model includes:

[0024] The initial pressure of the gas inside the bubble during the arc discharge process is obtained based on the gas generation model.

[0025] The shape parameters of the bubble are extracted based on the edge detection algorithm, and the equivalent radius of curvature of the bubble is obtained based on the shape parameters;

[0026] The pressure of the gas inside the bubble is obtained by correcting the initial pressure based on the equivalent radius of curvature.

[0027] In this scheme, since the bubbles have different shapes, and the initial pressure is obtained by assuming that the bubble shape is spherical, the initial pressure is corrected by obtaining the equivalent radius of curvature that characterizes the bubble shape. Through a closed-loop calculation system of initial spherical assumption, real-time shape recognition, equivalent radius of curvature, and pressure correction compensation, the accuracy of the gas pressure inside the bubble is improved.

[0028] Preferably, the step of correcting the initial pressure based on the equivalent radius of curvature to obtain the pressure of the gas inside the bubble includes:

[0029] The interfacial tension correction is obtained based on the equivalent radius of curvature and the oil interfacial tension; the viscous resistance correction is obtained based on the equivalent radius of curvature and the oil viscosity; and the inertial resistance correction is obtained based on the equivalent radius of curvature and the oil density.

[0030] The pressure of the gas inside the bubble is obtained by correcting the initial pressure based on the interfacial tension correction, viscous resistance correction, and inertial resistance correction.

[0031] In this scheme, due to the interaction between pressure and bubbles—that is, during arc discharge, bubbles do not exist in isolation, but rather expand / contract, pushing the surrounding oil to move, while the viscosity and inertia of the oil, in turn, hinder bubble deformation—and simultaneously, the surface tension and non-spherical deformation of the bubbles themselves alter the internal force balance. These interactions directly lead to a significant deviation between the initial pressure calculated by the gas generation model and the actual internal pressure. Therefore, by obtaining corrections for interfacial tension, viscous resistance, and inertial resistance to correct the initial pressure, not only is the interaction between pressure and bubbles considered, but also the morphological changes of the bubbles, significantly improving the accuracy of the gas pressure inside the bubbles, and thus significantly improving the accuracy of pressure simulation.

[0032] Preferably, the step of obtaining the pressure change cloud map inside the fuel tank based on the energy transfer model and the transient pressure acoustic model includes:

[0033] The relationship between pressure field strength and arc discharge time is obtained based on the energy transfer model and background pressure. The transient pressure acoustic model is used as a conditional constraint on the relationship between pressure field strength and arc discharge time, thereby obtaining pressure change contour maps.

[0034] The beneficial effects of this plan are:

[0035] By employing a gas compression model and considering the relationship between gas generation and arc energy, as well as the gas content in the oil during the operation of an oil-immersed transformer, a gas generation model is established. Based on the gas generation model and the relationship between arc energy and arc discharge time, an energy transfer model that can be processed by a transient pressure acoustic model is established. Specifically, the relationship between pressure field strength and arc discharge time obtained by combining the energy transfer model with background pressure is used as the input to the transient pressure acoustic model, achieving effective coupling of multiple physics fields. By accurately simulating the arc fault process from the key stages of gas generation and energy transfer, and leveraging the low computational complexity of the transient pressure acoustic model, pressure change cloud maps inside the oil tank are obtained. This overcomes the technical challenge of existing technologies in simultaneously ensuring the accuracy and efficiency of pressure simulation.

[0036] By obtaining the absolute difference between the physical quantities characterizing pressure in the benchmark simulation model and the comparative simulation model, and performing a union operation between the comparative simulation model with an absolute difference greater than a preset difference and the benchmark simulation model, a geometric simulation model is obtained. This ensures the accuracy of subsequent simulations while reducing the complexity of the geometric simulation model. It solves the technical problem of low computational efficiency caused by the complex internal structure of oil-immersed transformers and the redundancy of non-critical structures in arc fault pressure simulation.

[0037] By correcting the initial pressure using the interfacial tension correction, viscous resistance correction, and inertial resistance correction, not only is the interaction between pressure and bubbles considered, but also the morphological changes of bubbles are taken into account. This significantly improves the accuracy of the pressure of the gas inside the bubbles, and thus significantly improves the accuracy of pressure simulation.

[0038] This invention also provides a simulation system for the internal arc fault pressure of an oil-immersed transformer tank, applicable to the aforementioned method for simulating the internal arc fault pressure of an oil-immersed transformer tank, comprising:

[0039] The network model acquisition module is used to establish a geometric simulation model of the oil-immersed transformer tank and to perform network partitioning on the geometric simulation model to obtain the network model.

[0040] The gas generation model acquisition module is used to establish a gas compression model based on the network model, and to establish a gas generation model by combining the relationship between gas generation and arc energy and the gas content in oil during the operation of oil-immersed transformers.

[0041] The pressure simulation result acquisition module is used to establish an energy transfer model based on the gas generation model and the relationship between arc energy and arc discharge time, and to obtain the pressure change cloud map inside the oil tank based on the energy transfer model and the transient pressure acoustic model.

[0042] Preferably, the pressure simulation result acquisition module includes:

[0043] The pressure difference acquisition module is used to acquire the pressure of the gas inside the bubble during the arc discharge process based on the gas generation model, and to acquire the pressure difference between the gas inside the bubble and the oil interface based on the pressure of the gas inside the bubble.

[0044] The energy transfer model acquisition module is used to acquire the energy transfer model based on the relationship between pressure difference, arc energy and arc discharge time.

[0045] The pressure change cloud map acquisition module is used to acquire the pressure change cloud map inside the fuel tank based on the energy transfer model and the transient pressure acoustic model.

[0046] The beneficial effects of this plan are:

[0047] By employing a gas compression model, combining the relationship between gas generation and arc energy, and the gas content in the oil during the operation of an oil-immersed transformer, a gas generation model is established. Based on the gas generation model and the relationship between arc energy and arc discharge time, an energy transfer model that can be processed by a transient pressure acoustic model is established. The arc fault process is accurately simulated from the key stages of gas generation and energy transfer. Furthermore, the low computational complexity of the transient pressure acoustic model is utilized to obtain pressure change contour maps inside the oil tank. This overcomes the technical challenge of existing technologies in simultaneously ensuring the accuracy and efficiency of pressure simulation.

[0048] By accurately and quickly acquiring pressure change cloud maps, high-risk areas can be located rapidly, enabling timely responses and improving the safety of oil-immersed transformers.

[0049] The present invention also provides a computer device, including: a processor, a memory, and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the computer device is running, the processor communicates with the memory via the bus, and the processor executes the machine-readable instructions to perform the steps of the described method for simulating the internal arc fault pressure of an oil-immersed transformer tank. Attached Figure Description

[0050] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. The drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0051] Figure 1 This is a flowchart illustrating the pressure simulation method for internal arc faults in the oil tank of an oil-immersed transformer according to the present invention.

[0052] Figure 2 This is a flowchart of the gas generation model acquisition process in the oil-immersed transformer tank internal arc fault pressure simulation method of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only one preferred embodiment of this invention and are only used to explain this invention. They do not limit the scope of protection of this invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0054] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations (or steps) as sequential processes, many of the operations (or steps) can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but it may also have additional steps not included in the figures; the process may correspond to a method, function, procedure, subroutine, subroutine, etc.

[0055] Example 1: As Figure 1 As shown, the simulation method for arc fault pressure inside the oil tank of an oil-immersed transformer includes the following steps:

[0056] S1: Establish a geometric simulation model of the oil-immersed transformer tank, and perform network partitioning on the geometric simulation model to obtain a network model.

[0057] In some embodiments, a geometric simulation model of the oil-immersed transformer tank is established, including:

[0058] S11: Establish a benchmark simulation model including the outer shell of the fuel tank and the electromagnetic module inside the fuel tank. Based on any module inside the fuel tank other than the electromagnetic module, obtain several comparative simulation models with the benchmark simulation model.

[0059] S12: Under the same boundary conditions, obtain the absolute difference between the physical quantities characterizing pressure in the benchmark simulation model and the comparative simulation model;

[0060] S13: Perform a union operation between the comparative simulation model with an absolute difference greater than a preset difference and the benchmark simulation model to obtain the geometric simulation model.

[0061] The electromagnetic module specifically includes an internal iron core and coils. Boundary conditions include the density, viscosity, and specific heat capacity of the transformer oil, as well as the density and elastic modulus of the tank shell and the electromagnetic module. Users can flexibly set preset differences according to their requirements for the accuracy and efficiency of pressure simulation.

[0062] In this embodiment, the union operation specifically refers to: if the comparative simulation models with an absolute difference greater than a preset difference are model A and model B, where model A specifically includes the tank shell, the electromagnetic module inside the tank, and module a, and model B specifically includes the tank shell, the electromagnetic module inside the tank, and module b, then the geometric simulation model at this time includes the tank shell, the electromagnetic module inside the tank, module a, and module b. In this embodiment, by constructing a baseline simulation model, and then obtaining several comparative simulation models by sequentially adding structures, and under the same boundary conditions, obtaining the absolute difference of the physical quantities characterizing pressure features in the baseline simulation model and the comparative simulation models, the geometric simulation model is obtained by performing a union operation between the comparative simulation model with an absolute difference greater than a preset difference and the baseline simulation model. This ensures the accuracy of subsequent simulations while reducing the complexity of the geometric simulation model and improving the efficiency of pressure simulation. It solves the technical problem of low computational efficiency caused by the complex internal structure of oil-immersed transformers and the redundancy of non-critical structures in arc fault pressure simulation. In addition, to further simplify the computation, an on-axis line source is used to simulate the pressure source generated by arc fault discharge.

[0063] S2: Establish a gas compression model based on the network model, and establish a gas production model by combining the relationship between gas production and arc energy and the gas content in oil during the operation of oil-immersed transformers.

[0064] Specifically, such as Figure 2 As shown, a gas compression model is established based on a network model, and a gas production model is established by combining the relationship between gas production and arc energy and the gas content in oil during the operation of an oil-immersed transformer, including:

[0065] S21: Import the network model into the simulation software and establish a gas compression model by combining the relationship between the tank expansion coefficient and the tank pressure.

[0066] S22: Based on the law of conservation of mass, and combined with the relationship between gas production and arc energy, obtain the consumption function of oil volume consumed during arc discharge.

[0067] S23: Obtain the gas production model based on the gas compression model, combined with the oil gas content and consumption function.

[0068] In this embodiment, the relationship between the fuel tank expansion coefficient and the fuel tank pressure is as follows: In the formula, This indicates the fuel tank pressure. Indicates the dynamic amplification factor. Indicates the arc energy transfer coefficient. Indicates the energy of the electric arc. This represents the coefficient of thermal expansion of the fuel tank at a Kelvin temperature of [value missing]. At that time, the arc energy transfer coefficient Considering that the density of transformer oil changes under pressure, the specific relationship between transformer oil density and tank pressure is as follows: In the formula, This indicates the density of the transformer oil after compression. Indicates the original density of transformer oil. This indicates the bulk modulus of elasticity of transformer oil. The volume of the compressed transformer oil can be obtained from the density of the compressed transformer oil. In this embodiment, the purpose of the gas compression model is to obtain the volume of compressed transformer oil. The gas compression model specifically includes:

[0069] ;

[0070] ;

[0071] ;

[0072] In the formula, This indicates the mass of the compressed transformer oil.

[0073] The specific relationship between gas production and arc energy is as follows: , This indicates the gas production rate. Based on the relationship between gas production rate and arc energy, the gas production rate of transformer oil under any arc energy can be calculated. Early studies in oil circuit breakers showed that oil vapor accounted for 40% of the total gas bubble volume, while other gases accounted for 60%. A GIGRE working group report indicated that, in addition to oil vapor, the gas produced by arc discharge also contains 70%... 25% And 5% of other hydrocarbons ( and Based on the density of the gas at standard atmospheric pressure, the mass of the gas produced by an electric arc with energy E can be calculated. According to the law of conservation of mass, this mass is equal to the mass of the transformer oil consumed. The consumption function can be obtained from the mass of the consumed transformer oil and the density of the compressed transformer oil, and the volume of oil consumed can be obtained from the consumption function. Assuming an extreme case where the gas density during the arc is equal to the density of the transformer oil, the density of the compressed transformer oil can be calculated using the relationship between the tank expansion coefficient and tank pressure, and the relationship between the transformer oil density and tank pressure. Therefore, the volume of the compressed transformer oil can be obtained as follows: It only accounts for a small percentage of the gas content of oil. The volume change caused by the compression of the liquid medium is negligible, which is 0.49%. Therefore, the gas production model is specifically as follows: In the formula, This indicates the volume of gas in the tank during the arc discharge process. This indicates the volume of oil consumed.

[0074] S3: An energy transfer model is established based on the gas generation model and the relationship between arc energy and arc discharge time. Based on the energy transfer model and the transient pressure acoustic model, a pressure change cloud map inside the oil tank is obtained.

[0075] Specifically, an energy transfer model is established based on the gas generation model and the relationship between arc energy and arc discharge time, including:

[0076] S31: Obtain the pressure of the gas inside the bubble during the arc discharge process based on the gas generation model, and obtain the pressure difference between the gas inside the bubble and the oil interface based on the pressure of the gas inside the bubble.

[0077] S32: Obtain an energy transfer model based on the relationship between pressure difference, arc energy and arc discharge time.

[0078] In this embodiment, the expression for obtaining the pressure difference between the gas inside the bubble and the oil interface based on the pressure of the gas inside the bubble is as follows: , This represents the pressure difference between the gas and oil interface inside the bubble. This indicates the pressure of the gas inside the bubble. Equal to the gas pressure at the oil interface. Indicates atmospheric pressure. , This indicates the pressure of the gas inside the bubble. This indicates static oil pressure.

[0079] The specific relationship between arc energy and arc discharge time is as follows: , This represents the rate of increase of the electric arc energy over a certain period of time. This represents the arc discharge time. Energy transfer models include:

[0080] ;

[0081] ;

[0082] The relationship between arc energy and time can be converted into a relationship between pressure difference and time using an energy transfer model. In this embodiment, a gas generation model is established by combining a gas compression model with the relationship between gas production and arc energy, and the gas content in the oil during the operation of an oil-immersed transformer. Based on the gas generation model and the relationship between arc energy and arc discharge time, an energy transfer model that can be processed by a transient pressure acoustic model is established. By accurately simulating the arc fault process from the key stages of gas generation and energy transfer, the accuracy of the pressure simulation is ensured. Furthermore, the low computational complexity of the transient pressure acoustic model is used to obtain a pressure change cloud map inside the oil tank. This overcomes the technical problem of existing technologies that struggle to improve the efficiency of pressure simulation while ensuring its accuracy.

[0083] In some embodiments, obtaining the pressure of the gas inside the bubble during arc discharge based on a gas generation model includes:

[0084] The initial pressure of the gas inside the bubble during the arc discharge process is obtained based on the gas generation model.

[0085] The shape parameters of the bubble are extracted based on the edge detection algorithm, and the equivalent radius of curvature of the bubble is obtained based on the shape parameters;

[0086] The pressure of the gas inside the bubble is obtained by correcting the initial pressure based on the equivalent radius of curvature.

[0087] In this embodiment, the expression for obtaining the initial pressure of the gas inside the bubble during the arc discharge process based on the gas generation model is as follows: In the formula, This represents the initial pressure. The expression for obtaining the equivalent radius of curvature of the bubble based on its shape parameters is as follows: , Represents the equivalent radius of curvature. Indicates the major axis of the bubble, The minor axis represents the bubble, and the major and minor axes of the bubble are the shape parameters of the bubble.

[0088] In other embodiments, the pressure of the gas inside the bubble is obtained by correcting the initial pressure based on the equivalent radius of curvature, including:

[0089] The interfacial tension correction is obtained based on the equivalent radius of curvature and the oil interfacial tension; the viscous resistance correction is obtained based on the equivalent radius of curvature and the oil viscosity; and the inertial resistance correction is obtained based on the equivalent radius of curvature and the oil density.

[0090] The pressure of the gas inside the bubble is obtained by correcting the initial pressure based on the interfacial tension correction, viscous resistance correction, and inertial resistance correction.

[0091] In this embodiment, the expression for obtaining the interfacial tension correction amount based on the equivalent radius of curvature and the oil interfacial tension is as follows: , This indicates the amount of interfacial tension correction. This represents the interfacial tension of the oil. The expression for the correction to the viscous resistance, derived from the equivalent radius of curvature and oil viscosity, is as follows: , This indicates the correction amount for viscous resistance. This represents the oil viscosity. The expression for the inertial drag correction, based on the equivalent radius of curvature and oil density, is as follows: , This represents the correction for inertial drag. The pressure of the gas inside the bubble. By obtaining the correction values ​​for interfacial tension, viscous resistance, and inertial resistance to correct the initial pressure, not only is the interaction between pressure and bubbles taken into account, but also the morphological changes of bubbles are considered, which significantly improves the accuracy of the pressure of the gas inside the bubbles, and thus significantly improves the accuracy of pressure simulation.

[0092] In some embodiments, obtaining a pressure change cloud map inside the fuel tank based on an energy transfer model and a transient pressure acoustic model includes:

[0093] The relationship between pressure field strength and arc discharge time is obtained based on the energy transfer model and background pressure. The transient pressure acoustic model is used as a conditional constraint on the relationship between pressure field strength and arc discharge time, thereby obtaining pressure change contour maps.

[0094] In this embodiment, the background pressure refers to the pressure of the transformer oil before it is disturbed by an electric arc discharge. The pressure field strength is composed of the background pressure and the pressure difference. The transient pressure acoustic model is as follows: , This indicates the propagation speed of pressure waves in insulating oil. This indicates a strong pressure field. , Indicates background pressure. Represents the gradient operator, Indicates a dipole source. Represents the correlation coefficient. This represents a monopole source. In this embodiment, the pressure changes under different discharge durations can be simulated by using the relationship between the pressure field strength and the arc discharge time, and the constraints of the transient pressure acoustic model, thus obtaining an internal pressure change cloud map. The efficiency of pressure simulation is improved by utilizing the low computational complexity of the transient pressure acoustic model to obtain the pressure change cloud map inside the oil tank.

[0095] Example 2: This example also provides a simulation system for the internal arc fault pressure of an oil-immersed transformer tank, applicable to the aforementioned simulation method for the internal arc fault pressure of an oil-immersed transformer tank, including:

[0096] The network model acquisition module is used to establish a geometric simulation model of the oil-immersed transformer tank and to perform network partitioning on the geometric simulation model to obtain the network model.

[0097] The gas generation model acquisition module is used to establish a gas compression model based on the network model, and to establish a gas generation model by combining the relationship between gas generation and arc energy and the gas content in oil during the operation of oil-immersed transformers.

[0098] The pressure simulation result acquisition module is used to establish an energy transfer model based on the gas generation model and the relationship between arc energy and arc discharge time, and to obtain the pressure change cloud map inside the oil tank based on the energy transfer model and the transient pressure acoustic model.

[0099] Specifically, the pressure simulation result acquisition module includes:

[0100] The pressure difference acquisition module is used to acquire the pressure of the gas inside the bubble during the arc discharge process based on the gas generation model, and to acquire the pressure difference between the gas inside the bubble and the oil interface based on the pressure of the gas inside the bubble.

[0101] The energy transfer model acquisition module is used to acquire the energy transfer model based on the relationship between pressure difference, arc energy and arc discharge time.

[0102] The pressure change cloud map acquisition module is used to acquire the pressure change cloud map inside the fuel tank based on the energy transfer model and the transient pressure acoustic model.

[0103] The gas compression model specifically includes:

[0104] ;

[0105] ;

[0106] ;

[0107] In the formula, This indicates the fuel tank pressure. Indicates the dynamic amplification factor. Indicates the arc energy transfer coefficient. Indicates the energy of the electric arc. Indicates the coefficient of thermal expansion of the fuel tank. This indicates the density of the transformer oil after compression. Indicates the original density of transformer oil. This indicates the bulk modulus of elasticity of transformer oil. , This indicates the volume of compressed transformer oil. This represents the mass of the compressed transformer oil. In this embodiment, the purpose of the gas compression model is to obtain the volume of the compressed transformer oil.

[0108] The gas production model is specifically as follows In the formula, This indicates the volume of gas in the tank during the arc discharge process. This represents the volume of oil consumed. Energy transfer models include:

[0109] ;

[0110] ;

[0111] In the formula, This represents the pressure difference between the gas and oil interface inside the bubble. This indicates the pressure of the gas inside the bubble. Equal to the gas pressure at the oil interface. Indicates atmospheric pressure. , This indicates the pressure of the gas inside the bubble. Indicates hydrostatic pressure. This represents the rate of increase of the electric arc energy over a certain period of time. This indicates the duration of the electric arc discharge.

[0112] The transient pressure acoustic model is as follows: , This indicates the propagation speed of pressure waves in insulating oil. This indicates a strong pressure field. , Indicates background pressure. Represents the gradient operator, Indicates a dipole source. Represents the correlation coefficient. This represents a monopole source.

[0113] In this embodiment, a gas generation model is established by using a gas compression model, combining the relationship between gas generation and arc energy, and the gas content in the oil during the operation of an oil-immersed transformer. Based on the gas generation model and the relationship between arc energy and arc discharge time, an energy transfer model that can be processed by a transient pressure acoustic model is established. By accurately simulating the arc fault process from the key stages of gas generation and energy transfer, and taking advantage of the low computational complexity of the transient pressure acoustic model, a pressure change cloud map inside the oil tank is obtained. This overcomes the technical problem of existing technologies that struggle to improve the efficiency of pressure simulation while ensuring its accuracy.

[0114] Example 3: This example also provides a computer device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions that the processor can execute. When the computer device is running, the processor communicates with the memory through the bus, and the processor executes the machine-readable instructions to perform the steps of the oil-immersed transformer tank internal arc fault pressure simulation method.

[0115] The specific embodiments described above are preferred embodiments of the oil-immersed transformer tank internal arc fault pressure simulation method and system of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the specific embodiments described above. All equivalent changes made in accordance with the shape and structure of the present invention are within the protection scope of the present invention.

Claims

1. A method for simulating an internal arc fault pressure in an oil-immersed transformer tank, characterized in that, The method comprises the following steps: a geometric simulation model of the oil tank of the oil-immersed transformer is established, and a network model is obtained by network partitioning on the geometric simulation model; a gas compression model is established based on the network model, a gas production model is established in combination with a relationship between gas production and arc energy and an oil gas content in an operation process of the oil-immersed transformer; an energy transfer model is established based on the gas production model and a relationship between arc energy and arc discharge time, and a pressure change cloud diagram inside the oil tank is obtained based on the energy transfer model and a transient pressure acoustic model; the gas compression model is established based on the network model, the gas production model is established in combination with the relationship between the gas production and the arc energy and the oil gas content in the operation process of the oil-immersed transformer, and the gas compression model comprises: the network model is imported into simulation software, and a gas compression model is established in combination with a relationship between an oil tank expansion coefficient and an oil tank pressure; a consumption function of a consumed oil volume in an arc discharge process is obtained according to a mass conservation law and in combination with a relationship between gas production and arc energy; a gas production model is obtained in combination with the oil gas content and the consumption function according to the gas compression model; the energy transfer model is established based on the gas production model and a relationship between arc energy and arc discharge time, and the energy transfer model comprises: a pressure of gas inside a bubble in the arc discharge process is obtained based on the gas production model, and a pressure difference between the gas inside the bubble and an oil interface is obtained based on the pressure of the gas inside the bubble; the energy transfer model is obtained based on the pressure difference, the arc energy and the arc discharge time; the pressure change cloud diagram inside the oil tank is obtained based on the energy transfer model and a background pressure, the transient pressure acoustic model is taken as a conditional constraint of a relationship between a pressure field strength and the arc discharge time, and then the pressure change cloud diagram is obtained. the geometric simulation model of the oil tank of the oil-immersed transformer comprises:

2. The oil-immersed transformer tank internal arc fault pressure simulation method according to claim 1, characterized in that, a reference simulation model comprising an oil tank shell and an electromagnetic module inside the oil tank is established, and a plurality of comparison simulation models are obtained based on any module inside the oil tank except the electromagnetic module and the reference simulation model; absolute difference values of physical quantities representing pressure characteristics in the reference simulation model and the comparison simulation models are obtained under the same boundary conditions; the comparison simulation model and the reference simulation model whose absolute difference value is greater than a preset difference value are subjected to a set operation to obtain the geometric simulation model. the pressure of the gas inside the bubble in the arc discharge process is obtained based on the gas production model, and the pressure of the gas inside the bubble comprises:

3. The oil-immersed transformer tank internal arc fault pressure simulation method according to claim 1, characterized in that, an initial pressure of the gas inside the bubble in the arc discharge process is obtained based on the gas production model; a shape parameter of the bubble is extracted according to an edge detection algorithm, and an equivalent curvature radius of the bubble is obtained based on the shape parameter; the pressure of the gas inside the bubble is obtained by correcting the initial pressure according to the equivalent curvature radius. the pressure of the gas inside the bubble is obtained by correcting the initial pressure according to the equivalent curvature radius, and the pressure of the gas inside the bubble comprises:

4. The oil-immersed transformer tank internal arc fault pressure simulation method according to claim 3, characterized in that, an interface tension correction amount is obtained according to the equivalent curvature radius and an oil interface tension, a viscous resistance correction amount is obtained according to the equivalent curvature radius and an oil viscosity, and an inertial resistance correction amount is obtained based on the equivalent curvature radius and an oil density; the pressure of the gas inside the bubble is obtained by correcting the initial pressure based on the interface tension correction amount, the viscous resistance correction amount and the inertial resistance correction amount. ​ 5. An oil-immersed transformer tank internal arc fault pressure simulation system, suitable for the oil-immersed transformer tank internal arc fault pressure simulation method according to any one of claims 1 to 4, characterized in that, ​ The network model acquisition module is configured to establish a geometric simulation model of the oil tank of the oil-immersed transformer and perform network partitioning on the geometric simulation model to obtain a network model. The gas production model acquisition module is configured to establish a gas compression model based on the network model, and establish a gas production model in combination with a relationship between a gas production amount and an arc energy and an oil gas content in an operation process of the oil-immersed transformer. The pressure simulation result acquisition module is configured to establish an energy transfer model based on the gas production model and a relationship between the arc energy and an arc discharge time, and obtain a pressure change cloud diagram inside the oil tank based on the energy transfer model and a transient pressure acoustic model.

6. The oil-immersed transformer tank internal arc fault pressure simulation system according to claim 5, characterized in that, The pressure simulation result acquisition module includes: The pressure difference acquisition module is configured to obtain a pressure of gas inside a bubble in an arc discharge process based on the gas production model, and obtain a pressure difference between the gas inside the bubble and an oil interface based on the pressure of the gas inside the bubble. The energy transfer model acquisition module is configured to obtain the energy transfer model based on the pressure difference and the relationship between the arc energy and the arc discharge time. The pressure change cloud diagram acquisition module is configured to obtain the pressure change cloud diagram inside the oil tank based on the energy transfer model and the transient pressure acoustic model.

7. A computer device, characterized by: The computer device includes a processor, a memory and a bus. The memory stores machine readable instructions executable by the processor. When the computer device is running, the processor communicates with the memory through the bus. The processor executes the machine readable instructions to perform the steps of the oil-immersed transformer oil tank internal arc fault pressure simulation method according to any one of claims 1-4. ​

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