CN115081264A - COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method and system - Google Patents
COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method and system Download PDFInfo
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Abstract
The invention discloses a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method and a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis system, which define simulation parameters of rated voltage, current, oil tank temperature and the like of a transformer bushing; establishing a three-dimensional model of the transformer bushing and importing COMSOL; defining physical parameters such as relative dielectric constant, thermal conductivity, Young modulus and the like of the material in the sleeve; adding modules of static electricity, current, solid heat transfer, solid mechanics and multiple physical fields, and setting boundary conditions of all the physical fields; determining a grid precision division model and setting solver parameters; carrying out finite element simulation calculation; and drawing the distribution conditions of the electric field, the temperature and the stress under the coupling of multiple physical fields. When the simulation transformer bushing works at a rated voltage, the distribution condition of each key parameter under the environment of multi-physical-field coupling is considered, and a reference standard is provided for judging whether the transformer bushing works in a normal state.
Description
Technical Field
The invention belongs to the technical field of high voltage and insulation, and relates to a transformer bushing electricity-heat-machine coupling simulation analysis method and system based on COMSOL.
Background
The transformer bushing is a main insulation device outside the transformer box, needs to be used as a lead wire for insulation against the ground, and plays a role in fixing the lead wire, so the transformer bushing needs good electrical strength and enough mechanical strength; meanwhile, the transformer needs to have good thermal stability due to the fact that large load current passes through the transformer for a long time in the running process of the transformer, and can bear instant overheating when short-circuit current passes through the transformer. The transformer bushing plays an extremely important role in a power system, and various parameters are required to be kept normal under a rated working condition.
When the transformer bushing works, the transformer bushing is in a more complex state due to the influence of a plurality of physical fields such as electricity, heat, machinery and the like. The existence of the current causes the generation of joule heat, and meanwhile, an electric field and temperature rise also generate mechanical power, thermal stress and the like to cause certain influence on the mechanical structure of the transformer bushing.
For transformer bushings with complex working states, simulation analysis is mostly carried out on a single physical field in the existing research; obviously, the complete working condition information of the transformer bushing cannot be reflected by the simulation aiming at the single physical field, so a multi-physical-field simulation analysis method comprising a full-flow transformer bushing is urgently needed.
Disclosure of Invention
The invention aims to solve the problems in the prior art, provides a transformer bushing electricity-heat-machine coupling simulation analysis method and system based on COMSOL, and aims to solve the technical problem that in the prior art, most of transformer bushings with complex working states are subjected to simulation analysis aiming at a single physical field, and the complete working condition information of the transformer bushings cannot be reflected.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the invention provides a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method which is characterized by comprising the following steps of:
establishing a transformer bushing three-dimensional model according to parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis, and introducing the transformer bushing three-dimensional model into COMSOL;
respectively determining material attributes required for performing the transformer bushing electricity-heat-machine coupling simulation according to the transformer bushing materials;
adding physical fields required by transformer bushing electricity-heat-machine coupling simulation analysis, and respectively setting boundary conditions of the physical fields and coupling according to actual conditions and parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis;
and setting a mesh precision subdivision three-dimensional model mesh, setting solver parameters to accelerate simulation convergence, and realizing the transformer bushing electricity-heat-machine coupling finite element simulation calculation.
Preferably, the parameters required for the transformer bushing electro-thermo-mechanical coupling simulation analysis include geometric parameters and external variables of the transformer bushing;
the geometric structure parameters comprise the height and the thickness of a transformer bushing capacitive screen and the size and the number of umbrellas; external variables include rated voltage, current, and tank temperature;
establishing a transformer bushing three-dimensional model comprising a guide rod, a capacitive screen, upper and lower porcelain sleeves, a flange and a voltage-sharing ball part;
the transformer bushing three-dimensional model is simplified in order to improve the simulation efficiency on the premise of ensuring the simulation accuracy:
1) removing complex characteristics of the bushing part of the transformer;
2) simplifying the fillet structure of the transformer bushing part into a right-angle structure;
3) and removing the bolt and the nut in the transformer bushing.
Preferably, the materials required for performing the electric-thermal-mechanical coupling simulation of the transformer bushing comprise copper laid at a guide rod, oil paper and aluminum foil laid at a capacitive screen, transformer oil laid inside the bushing and at an oil tank, ceramics laid at upper and lower porcelain bushings, flanges and steel laid at a pressure equalizing ball;
the material properties required for performing the transformer bushing electricity-heat-machine coupling simulation comprise the relative dielectric constant and the electrical conductivity required in electric field analysis, the thermal conductivity and the constant-pressure heat capacity required in solid heat transfer field analysis, and the Young modulus and the Poisson ratio required in solid mechanics analysis;
in the running process of the transformer bushing, the influence of temperature rise generated when the transformer bushing runs is simulated by adopting a linear resistivity model, the change of the resistivity of the material along with the temperature is simulated, and the calculation of the conductivity sigma of the material is shown as a formula (1):
where ρ is 0 For reference resistivity, T ref T is the temperature and alpha is the temperature coefficient of resistance.
Preferably, the physical fields required for the added transformer bushing electro-thermo-mechanical coupling simulation analysis include electrostatic, current and solid heat transfer and solid mechanical fields.
Preferably, for a transformer bushing, the system of equations satisfied by the added electrostatic field is as shown in equation (2):
wherein D is the electric flux density, E is the electric field intensity,
is an electric potential; according to an equation set satisfied by the electrostatic field, the boundaries required to be set in the electrostatic field simulation of the transformer bushing are potential, grounding and charge conservation.
Preferably, for a transformer bushing, the system of equations that the added current field needs to satisfy is as shown in equation (3):
wherein J is a current density vector, sigma is the conductivity of the material, and E is the electric field strength; according to the equation set satisfied by the current field, the transformer bushing is provided with the boundaries of current, grounding and contact impedance in the current field simulation.
Preferably, for a transformer bushing, the added solid heat transfer field satisfies the equation shown in equation (4):
wherein, rho, C p K is the density, constant pressure heat capacity and heat conductivity coefficient of the material respectively, T is the temperature, u is the fluid flow rate, and Q is the heat source distribution; according to an equation set met by a solid heat transfer field, the boundaries required to be set in the simulation of the solid heat transfer field of the transformer bushing are temperature and heat flux;
when a current field and a solid heat transfer field are carried outIn the coupling, the electromagnetic heat generated in the current field is used as a part of the heat source for calculation, and the Joule heat Q e Is calculated as shown in equation (5):
Q e ＝J·E (5)。
preferably, for a transformer bushing, the added solid mechanical field satisfies the equation shown in equation (6):
wherein S is the stress tensor, F v Is force per unit volume; in the simulation process of the transformer bushing in the solid mechanical field, a boundary condition of fixed constraint needs to be added to the transformer bushing.
Preferably, when the influence of the electrostatic field on the structure of the transformer bushing is considered, the action of the electromagnetic stress is analyzed, the electromechanical power is added into the multi-physical-field module, the electrostatic field and the solid mechanical field are selected, and the electromagnetic stress sigma is EM Is calculated as shown in equation (7):
wherein δ is a Kronecker function;
when the influence caused by the solid heat transfer field is considered, the thermal expansion caused by temperature rise is analyzed, the thermal expansion is added in the multi-physical-field module, the solid heat transfer and the solid mechanics are selected, and the thermal stress belongs to the element th Is calculated as shown in equation (8):
∈ th ＝α(t)(T-T 0 ) (8)
wherein α (T) is the coefficient of thermal expansion of the material, T 0 Is the initial temperature.
The invention provides a system of a transformer bushing electricity-heat-machine coupling simulation analysis method based on COMSOL, which comprises the following steps:
the model building module is used for building a transformer bushing three-dimensional model according to parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis and guiding the transformer bushing three-dimensional model into COMSOL;
the material attribute determining module is used for respectively determining the material attributes required by the transformer bushing electricity-heat-machine coupling simulation according to the transformer bushing materials;
the system comprises a physical field boundary condition determining and coupling module, a transformer bushing electric-thermal-mechanical coupling simulation analysis module and a control module, wherein the physical field boundary condition determining and coupling module is used for adding a physical field required by the transformer bushing electric-thermal-mechanical coupling simulation analysis, and respectively setting boundary conditions of each physical field and coupling according to actual conditions and parameters required by the transformer bushing electric-thermal-mechanical coupling simulation analysis;
the transformer bushing electric-thermal-mechanical coupling finite element simulation calculation module is used for setting a mesh precision subdivision three-dimensional model mesh and setting solver parameters to accelerate simulation convergence, so that the transformer bushing electric-thermal-mechanical coupling finite element simulation calculation is realized.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method, which provides a reference standard for judging whether a transformer bushing works in a normal state or not by considering the distribution condition of each key parameter under the environment of multi-physical field coupling. The problem of to the transformer bushing that operating condition is complicated among the prior art, carry out simulation analysis to single physical field mostly, can not embody the complete operating mode information of transformer bushing is solved.
The invention provides a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method system, which divides the system into a model building module, a material attribute determining module required by coupling simulation, a physical field boundary condition determining and coupling module and a transformer bushing electricity-heat-machine coupling finite element simulation calculating module, adopts a modularization idea to make the modules independent from each other, and is convenient for unified management of the modules.
Drawings
In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a flow chart of COMSOL-based transformer bushing electro-thermal-mechanical coupling simulation analysis according to the present invention.
Fig. 2 is a three-dimensional model diagram of the transformer bushing of the present invention.
Fig. 3 is a diagram showing potential distribution of the transformer bushing electro-thermo-mechanical coupling simulation of the present invention.
Fig. 4 is a diagram of a transformer bushing electro-thermal-mechanical coupling simulation system of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.
In the description of the embodiments of the present invention, it should be noted that, if the terms "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which the product of the present invention is used to usually place, it is only for convenience of describing the present invention and simplifying the description, but it is not necessary to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The invention is described in further detail below with reference to the accompanying drawings:
as shown in fig. 1, the method for simulating and analyzing the electrical-thermal-mechanical coupling of the transformer bushing based on COMSOL provided by the invention comprises the following steps:
establishing a transformer bushing three-dimensional model according to parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis, and introducing the transformer bushing three-dimensional model into COMSOL;
respectively determining material attributes required for performing the transformer bushing electricity-heat-machine coupling simulation according to the transformer bushing materials;
adding physical fields required by transformer bushing electricity-heat-machine coupling simulation analysis, and respectively setting boundary conditions of the physical fields and coupling according to actual conditions and parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis;
setting a mesh precision subdivision three-dimensional model mesh, setting solver parameters to accelerate simulation convergence, and realizing the transformer bushing electricity-heat-machine coupling finite element simulation calculation;
and performing post-processing on the result of the simulation calculation, wherein the post-processing process required to be performed comprises the step of drawing the distribution conditions of the potential, the electric field, the temperature and the stress of the transformer bushing in the multi-physical-field coupling environment.
The invention provides a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method, which specifically comprises the following steps of:
step 1: parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis are defined.
Considering a 330kV transformer bushing, the parameters that need to be defined include two parts: geometry parameters and external variables. The geometric structure parameters comprise the height and thickness of a transformer bushing capacitive screen, the size and number of umbrellas and the like, and the external variables comprise rated voltage and current of the transformer bushing, temperature of a connecting oil tank and the like.
Step 2: and establishing a three-dimensional model of the transformer bushing and guiding the three-dimensional model into COMSOL.
For improving simulation efficiency under the prerequisite of guaranteeing the simulation accuracy, simplify transformer bushing's model, include: removing small but complex features of the transformer bushing portion; simplifying the fillet structures of a flange, an umbrella and the like into right-angle structures; and removing parts such as bolts, nuts and the like which are not necessary for simulation.
Constructing each main part of the transformer bushing according to the form of parts by using three-dimensional modeling software, wherein the main parts comprise a guide rod, a capacitive screen, upper and lower porcelain sleeves, a flange, a voltage-sharing ball and the like, and the parts are shown in figure 2; and adds an infinite field for the model, denoted as infinity.
And step 3: and respectively determining the material properties required for simulation according to the transformer bushing material.
According to the structure of the transformer bushing, determining the materials to be laid of each part as follows: copper laid at the guide rod, transformer oil laid inside the sleeve and at the oil tank, oil paper and aluminum foil laid at the capacitive screen, ceramics laid at the upper and lower porcelain bushings, and steel laid at the flange and the pressure equalizing ball.
For the above materials, the material properties required to be set in the electro-thermal-mechanical coupling simulation include the relative dielectric constant, the electrical conductivity and the like required in the electric field analysis, the thermal conductivity, the constant-pressure heat capacity and the like required in the solid heat transfer field analysis, and the young modulus, the poisson ratio and the like required in the solid mechanical analysis.
During the operation of the transformer bushing, the temperature of the components will rise due to the electromagnetic heat, resulting in a change in the resistivity of the material. Here, a linear resistivity model is used to simulate the change of resistivity with temperature, and the conductivity σ of the material is calculated as shown in formula (1):
where ρ is 0 For reference resistivity, T ref α is a temperature coefficient of resistance as a reference temperature.
And 4, step 4: adding physical fields required by simulation analysis, and respectively setting boundary conditions of the physical fields according to actual conditions and defined simulation parameters and coupling.
Static electricity, current, solid heat transfer and solid mechanics physical field modules are added in the COMSOL, and multiple physical field modules are added for coupling between physical fields.
In the electrostatic field, the equation system required to be satisfied by the transformer bushing is shown in formula (2):
wherein D is the electric flux density, E is the electric field intensity,
is an electrical potential.
According to the equation set, the boundary conditions required to be set in the electrostatic field simulation of the transformer bushing are as follows: adding at the guide rod
Setting grounding conditions at the flange and at infinity; setting a low dielectric constant thin gap condition at the junction of the layered structure of the capacitive screen, wherein the relative dielectric constant is the same as that of aluminum; charge conservation is provided for air and transformer oil.
For a transformer bushing, the system of equations that the added current field needs to satisfy is shown in equation (3):
where J is the current density vector and σ is the conductivity of the material.
For the transformer bushing, the added current field needs to satisfy the following conditions: adding a 1250A current terminal at the upper end of the guide rod, and forming a closed loop at the lower end through grounding; contact impedances are provided at the junctions of the layered structure of the capacitive screen, wherein the electrical conductivity and the relative permittivity are the same as those of aluminum.
The equation conditions that the transformer bushing needs to satisfy in the solid heat transfer module are shown in equation (4):
wherein, rho, C p And k are density, constant-pressure heat capacity and heat conductivity coefficient of the material respectively, T is temperature, u is fluid flow rate, and Q is heat source distribution.
The boundary conditions required to be set in the temperature field simulation of the transformer bushing are as follows: setting the area of the transformer bushing model, which is made of air and transformer oil, as the boundary condition of the fluid; the temperature of the transformer oil is constant at 90 degrees; and (3) adding heat flux conditions for an infinite element domain, selecting convection heat flux and setting a corresponding heat transfer coefficient h to be 8.
When the current field is coupled with the solid heat transfer field, electromagnetic heat needs to be added in the multi-physical field module and the current field and the solid heat transfer need to be selected, namely, the electromagnetic heat generated in the current field is used as a part of heat source for calculation, and the Joule heat Q is calculated e Is calculated as shown in equation (5):
Q e ＝J·E (5)
for a transformer bushing, the solid mechanical field to be satisfied satisfies the equation shown in equation (6):
wherein S is the stress tensor, F v Is force per unit volume.
In the simulation process of the solid mechanical field, a fixed constraint needs to be added on the solid contact surface of the transformer bushing as a boundary condition.
The stress-related physical field coupling analysis mainly includes electromagnetic stress and thermal stress.
When the influence of the electrostatic field on the structure of the transformer bushing is considered, the action of electromagnetic stress is analyzed, electromechanical power is added into the multi-physical-field module, the electrostatic field and the solid mechanical field are selected, and the electromagnetic stress sigma is EM Is calculated as shown in equation (7):
where δ is the Kronecker function.
When the influence caused by a solid heat transfer field is considered, analyzing the thermal expansion caused by temperature rise, adding the thermal expansion into the multi-physical-field module, selecting the solid heat transfer and the solid mechanics, and selecting the thermal stress epsilon th Is calculated as shown in equation (8):
∈ th ＝α(t)(T-T 0 ) (8)
where α (T) is the coefficient of thermal expansion of the material, T 0 Is the initial temperature.
And 5: and setting grid precision subdivision three-dimensional model grids, and setting solver parameters to accelerate simulation convergence.
Step 6: and carrying out electric-thermal-mechanical coupling finite element simulation calculation on the transformer bushing.
And 7: and carrying out post-processing on the result of the simulation calculation.
For the result of the calculation, the post-processing process required to be performed includes drawing the distribution of the potential, the electric field, the temperature and the stress of the transformer bushing in the multi-physics coupling environment, as shown in fig. 3.
The invention provides a transformer bushing electricity-heat-machine coupling simulation analysis method based on COMSOL, as shown in FIG. 4, comprising:
the model building module is used for building a transformer bushing three-dimensional model according to parameters required by transformer bushing electricity-heat-machine coupling simulation analysis and guiding the transformer bushing three-dimensional model into COMSOL;
the material attribute determining module is used for respectively determining the material attributes required by the transformer bushing electricity-heat-machine coupling simulation according to the transformer bushing materials;
the system comprises a physical field boundary condition determining and coupling module, a transformer bushing electric-thermal-mechanical coupling simulation analysis module and a control module, wherein the physical field boundary condition determining and coupling module is used for adding a physical field required by the transformer bushing electric-thermal-mechanical coupling simulation analysis, and respectively setting boundary conditions of each physical field and coupling according to actual conditions and parameters required by the transformer bushing electric-thermal-mechanical coupling simulation analysis;
the transformer bushing electric-thermal-mechanical coupling finite element simulation calculation module is used for setting a mesh precision subdivision three-dimensional model mesh and setting solver parameters to accelerate simulation convergence, so that the transformer bushing electric-thermal-mechanical coupling finite element simulation calculation is realized.
The invention provides a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method and a COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis system, which are characterized in that firstly, simulation parameters such as rated voltage, current, oil tank temperature and the like of a transformer bushing are defined; establishing a three-dimensional model of the transformer bushing and importing COMSOL; defining physical parameters such as relative dielectric constant, thermal conductivity, Young modulus and the like of the material in the sleeve; adding modules of static electricity, current, solid heat transfer, solid mechanics and multiple physical fields, and setting boundary conditions of all the physical fields; determining a grid precision division model and setting solver parameters; carrying out finite element simulation calculation; and drawing the distribution conditions of the electric field, the temperature and the stress under the coupling of multiple physical fields. When the simulated transformer bushing works at a rated voltage, the distribution condition of each key parameter under the environment of multi-physical-field coupling is considered, and a reference standard is provided for judging whether the transformer bushing works in a normal state.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A transformer bushing electricity-heat-machine coupling simulation analysis method based on COMSOL is characterized by comprising the following steps:
establishing a transformer bushing three-dimensional model according to parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis, and introducing the transformer bushing three-dimensional model into COMSOL;
respectively determining material attributes required for performing the transformer bushing electricity-heat-machine coupling simulation according to the transformer bushing materials;
adding physical fields required by transformer bushing electricity-heat-machine coupling simulation analysis, and respectively setting boundary conditions of the physical fields and coupling according to actual conditions and parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis;
and setting a mesh precision subdivision three-dimensional model mesh, setting solver parameters to accelerate simulation convergence, and realizing the transformer bushing electricity-heat-machine coupling finite element simulation calculation.
2. A COMSOL-based transformer bushing electric-thermal-mechanical coupling simulation analysis method according to claim 1, wherein the parameters required for transformer bushing electric-thermal-mechanical coupling simulation analysis include geometric parameters and external variables of the transformer bushing;
the geometric structure parameters comprise the height and the thickness of a transformer bushing capacitive screen and the size and the number of umbrellas; external variables include rated voltage, current, and tank temperature;
establishing a transformer bushing three-dimensional model comprising a guide rod, a capacitive screen, upper and lower porcelain sleeves, a flange and a voltage-sharing ball part;
the transformer bushing three-dimensional model is simplified in order to improve the simulation efficiency on the premise of ensuring the simulation accuracy:
1) removing complex characteristics of the bushing part of the transformer;
2) simplifying the fillet structure of the transformer bushing part into a right-angle structure;
3) and removing the bolt and the nut in the transformer bushing.
3. The COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method of claim 2, wherein the materials required for performing the transformer bushing electricity-heat-machine coupling simulation include copper laid at a guide rod, oiled paper and aluminum foil laid at a capacitive screen, transformer oil laid inside a bushing and at an oil tank, ceramics laid at upper and lower porcelain bushings, flanges and steel laid at a pressure equalizing ball;
the material properties required for performing the transformer bushing electricity-heat-machine coupling simulation comprise the relative dielectric constant and the electrical conductivity required in electric field analysis, the thermal conductivity and the constant-pressure heat capacity required in solid heat transfer field analysis, and the Young modulus and the Poisson ratio required in solid mechanical analysis;
in the running process of the transformer bushing, the influence of temperature rise generated in the running process of the transformer bushing is simulated by adopting a linear resistivity model to simulate the change of the resistivity of a material along with the temperature, and the calculation of the conductivity sigma of the material is shown as a formula (1):
where ρ is 0 For reference resistivity, T ref T is the temperature and alpha is the temperature coefficient of resistance.
4. The COMSOL-based transformer bushing electric-thermal-mechanical coupling simulation analysis method of claim 3, wherein the physical fields required for adding the transformer bushing electric-thermal-mechanical coupling simulation analysis include electrostatic field, current field and solid heat transfer field and solid mechanics field.
5. The COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method of claim 4, wherein for a transformer bushing, the added electrostatic field satisfies the equation set shown in equation (2):
wherein D is the electric flux density, E is the electric field intensity,
is an electric potential; according to an equation set met by the electrostatic field, the boundaries required to be set in the electrostatic field simulation of the transformer bushing are potential, grounding and charge conservation.
6. The COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method of claim 5, wherein for a transformer bushing, the added current field needs to satisfy the equation set as shown in equation (3):
wherein J is a current density vector, sigma is the conductivity of the material, and E is the electric field strength; according to the equation set satisfied by the current field, the transformer bushing is provided with the boundaries of current, grounding and contact impedance in the current field simulation.
7. The COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method of claim 6, wherein for a transformer bushing, the added solid heat transfer field satisfies the equation shown in equation (4):
wherein, rho, C p K is the density, constant pressure heat capacity and heat conductivity coefficient of the material respectively, T is the temperature, u is the fluid flow rate, and Q is the heat source distribution; according to an equation set met by a solid heat transfer field, the boundaries required to be set in the simulation of the solid heat transfer field of the transformer bushing are temperature and heat flux;
when the current field is coupled with the solid heat transfer field, the electromagnetic heat generated in the current field is used as a part of heat source for calculation, namely Joule heat Q e Is calculated as shown in equation (5):
Q e ＝J·E (5)。
8. the COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method of claim 7, wherein for a transformer bushing, the added solid mechanical field satisfies the equation shown in equation (6):
wherein S is the stress tensor, F v Is force per unit volume; in the simulation process of the transformer bushing in the solid mechanical field, a boundary condition of fixed constraint needs to be added to the transformer bushing.
9. A COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method according to claim 8, characterized in that, when considering the influence of electrostatic field on the structure of transformer bushing, analyzing the effect of electromagnetic stress, adding machine electricity in multi-physics field module and selecting electrostatic field and solid mechanics field, electromagnetic stress σ EM Is calculated as shown in equation (7):
wherein δ is a Kronecker function;
when the influence caused by the solid heat transfer field is considered, the thermal expansion caused by temperature rise is analyzed, the thermal expansion is added in the multi-physical-field module, the solid heat transfer and the solid mechanics are selected, and the thermal stress belongs to the element th Is calculated as shown in equation (8):
∈ th ＝α(t)(T-T 0 ) (8)
where α (T) is the coefficient of thermal expansion of the material, T 0 Is the initial temperature.
10. The system adopting the COMSOL-based transformer bushing electricity-heat-machine coupling simulation analysis method of any claim 1-9, is characterized by comprising the following steps:
the model building module is used for building a transformer bushing three-dimensional model according to parameters required by the transformer bushing electricity-heat-machine coupling simulation analysis and guiding the transformer bushing three-dimensional model into COMSOL;
the material attribute determining module is used for respectively determining the material attributes required by the transformer bushing electricity-heat-machine coupling simulation according to the transformer bushing materials;
the system comprises a physical field boundary condition determining and coupling module, a transformer bushing electric-thermal-mechanical coupling simulation analysis module and a control module, wherein the physical field boundary condition determining and coupling module is used for adding a physical field required by the transformer bushing electric-thermal-mechanical coupling simulation analysis, and respectively setting boundary conditions of each physical field and coupling according to actual conditions and parameters required by the transformer bushing electric-thermal-mechanical coupling simulation analysis;
the transformer bushing electric-thermal-mechanical coupling finite element simulation calculation module is used for setting a mesh precision subdivision three-dimensional model mesh and setting solver parameters to accelerate simulation convergence, so that the transformer bushing electric-thermal-mechanical coupling finite element simulation calculation is realized.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113466636A (en) * | 2021-05-24 | 2021-10-01 | 广西大学 | Insulation simulation modeling method for capacitive bushing based on finite element considering uneven degradation state |
| CN115906555A (en) * | 2022-10-12 | 2023-04-04 | 中建二局安装工程有限公司 | COMSOL-based prediction method for residual stress and leakage magnetic field thereof in welding process |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113466636A (en) * | 2021-05-24 | 2021-10-01 | 广西大学 | Insulation simulation modeling method for capacitive bushing based on finite element considering uneven degradation state |
| CN115906555A (en) * | 2022-10-12 | 2023-04-04 | 中建二局安装工程有限公司 | COMSOL-based prediction method for residual stress and leakage magnetic field thereof in welding process |
| CN115906555B (en) * | 2022-10-12 | 2023-09-19 | 中建二局安装工程有限公司 | Residual stress and leakage magnetic field prediction method in welding process based on COMSOL |
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