Capacitor temperature field analysis method and device based on harmonic voltage, and storage medium

Abstract

The application relates to the technical field of power equipment, and discloses a capacitor temperature field analysis method based on harmonic voltage, equipment and a storage medium, the method comprising the following steps: constructing a non-uniform loss model according to circuit parameters of a capacitor when the capacitor operates based on harmonic voltage, wherein the circuit parameters are used to represent the state of the capacitor; determining the loss distribution of the capacitor according to the non-uniform loss model; and determining the temperature field distribution of the capacitor according to the loss distribution and in combination with a corresponding thermodynamic model of the capacitor. The technical scheme provided by the application can accurately obtain the temperature field distribution of the capacitor under harmonic voltage by constructing a non-uniform loss model of the capacitor working under harmonic voltage, obtaining the loss distribution of the capacitor, and in combination with the corresponding thermodynamic model of the capacitor, so that the accuracy of the temperature field distribution can be improved, and the accuracy of the relationship between the temperature field and the loss of the capacitor can be improved.

Description

Technical Field

[0001] This invention relates to the field of power equipment technology, and in particular to a method, device and storage medium for analyzing the temperature field of a capacitor based on harmonic voltage. Background Technology

[0002] Capacitors are important and commonly used devices in power grids, playing a role in energy storage and filtering during power transmission and distribution. However, capacitors experience losses during operation, which can affect the normal operation of the power grid.

[0003] In related technologies, the loss of a capacitor can be calculated using a lumped parameter model, and the thermal field and temperature field in the capacitor can be established through finite element analysis, thereby determining the correlation between the loss distribution and the temperature field distribution of the capacitor.

[0004] However, for complex voltage situations such as harmonic voltages, it is impossible to accurately simulate the temperature field of the capacitor, and therefore it is impossible to accurately obtain the relationship between the temperature field and the capacitor loss. Summary of the Invention

[0005] Based on this, in order to address the problem that existing methods cannot accurately simulate the temperature field of capacitors for complex voltages such as harmonic voltages, and thus cannot accurately determine the relationship between the temperature field and capacitor losses, a capacitor temperature field analysis method, device, and storage medium based on harmonic voltage is proposed.

[0006] In a first aspect, a method for analyzing the temperature field of a capacitor based on harmonic voltage is provided, the method comprising:

[0007] A non-uniform loss model is constructed based on the circuit parameters of the capacitor operating under harmonic voltage, wherein the circuit parameters are used to represent the state of the capacitor.

[0008] Based on the non-uniform loss model, the loss distribution of the capacitor is determined;

[0009] Based on the loss distribution and the corresponding thermodynamic model of the capacitor, the temperature field distribution of the capacitor is determined.

[0010] Optionally, determining the temperature field distribution of the capacitor based on the loss distribution and the corresponding thermodynamic model includes:

[0011] Construct the thermodynamic model corresponding to the capacitor. In the thermodynamic model, the first and second surfaces of the medium are both provided with plates. The medium includes multiple temperature micro-elements. The first and second surfaces are parallel.

[0012] Based on the loss distribution and the temperature micro-element, the temperature field distribution of the capacitor is generated.

[0013] Optionally, generating the temperature field distribution of the capacitor based on the loss distribution and the temperature micro-element includes:

[0014] Based on the plate loss density of the plates in the thermodynamic model, the first heat transferred by the medium in a first direction is determined, where the first direction is from the first surface to the second surface;

[0015] Based on the dielectric loss density of the medium, the second heat transmitted by the medium in a second direction is determined, wherein the second direction is perpendicular to the first direction;

[0016] The temperature field distribution is generated based on the first heat and the second heat.

[0017] Optionally, the temperature field distribution includes: a medium temperature field distribution and an electrode temperature field distribution, wherein the medium temperature field distribution is used to represent the temperature distribution of the medium, and the electrode temperature field distribution is used to represent the temperature distribution of the electrode.

[0018] The step of generating the temperature field distribution based on the first heat and the second heat includes:

[0019] The medium temperature field distribution is generated based on the first heat and the second heat.

[0020] The medium boundary temperature of the medium is obtained by calculating based on the loss distribution, the first heat and the second heat.

[0021] The plate temperature field distribution is generated based on the medium temperature field distribution and the medium boundary temperature.

[0022] Optionally, the step of calculating the medium boundary temperature based on the loss distribution, the first heat, and the second heat includes:

[0023] The medium boundary temperature is obtained by calculating the loss distribution, the first heat, and the second heat using the heat distribution and Stefan's law.

[0024] Optionally, determining the loss distribution of the capacitor based on the non-uniform loss model includes:

[0025] The non-uniform loss model is differentiated to obtain a differential structure.

[0026] The loss distribution of the capacitor is obtained based on the differential structure.

[0027] Optionally, obtaining the loss distribution of the capacitor based on the differential structure includes:

[0028] Based on the differential structure, the voltage differential equation and the current differential equation of the capacitor are obtained. The voltage differential equation is used to represent the voltage distribution on the plates of the capacitor, and the current differential equation is used to represent the current distribution on the plates of the capacitor.

[0029] Based on the voltage differential equation and the current differential equation, the total loss, plate loss, and dielectric loss of the capacitor are determined, and the total loss, plate loss, and dielectric loss constitute the loss distribution.

[0030] Optionally, after determining the temperature field distribution of the capacitor based on the loss distribution and the corresponding thermodynamic model, the method further includes:

[0031] Based on the loss distribution and the temperature field distribution, the correspondence between the capacitor's loss and the temperature field is determined.

[0032] Secondly, a capacitor temperature field analysis device based on harmonic voltage is provided, the device comprising:

[0033] The model building module is used to construct a non-uniform loss model based on the circuit parameters of the capacitor operating under harmonic voltage, wherein the circuit parameters are used to represent the state of the capacitor.

[0034] The loss determination module is used to determine the loss distribution of the capacitor based on the non-uniform loss model.

[0035] The temperature field determination module is used to determine the temperature field distribution of the capacitor based on the loss distribution and the corresponding thermodynamic model of the capacitor.

[0036] Optionally, the temperature field determination module is specifically used to construct the thermodynamic model corresponding to the capacitor. In the thermodynamic model, both the first and second surfaces of the dielectric are provided with plates, and the dielectric includes multiple temperature micro-elements. The first and second surfaces are parallel. Based on the loss distribution and combined with the temperature micro-elements, the temperature field distribution of the capacitor is generated.

[0037] Optionally, the temperature field determination module is further configured to determine, based on the plate loss density of the plates in the thermodynamic model, a first heat transmitted by the medium in a first direction, wherein the first direction is the direction from the first surface to the second surface; determine, based on the medium loss density of the medium, a second heat transmitted by the medium in a second direction, wherein the second direction is perpendicular to the first direction; and generate the temperature field distribution based on the first heat and the second heat.

[0038] Optionally, the temperature field distribution includes: a medium temperature field distribution and an electrode temperature field distribution, wherein the medium temperature field distribution is used to represent the temperature distribution of the medium, and the electrode temperature field distribution is used to represent the temperature distribution of the electrode.

[0039] The temperature field determination module is further specifically used to generate the medium temperature field distribution based on the first heat and the second heat; to calculate the medium boundary temperature based on the loss distribution, the first heat and the second heat; and to generate the electrode temperature field distribution based on the medium temperature field distribution and the medium boundary temperature.

[0040] Optionally, the temperature field determination module is further specifically used to calculate the medium boundary temperature based on the heat convection formula and Stefan's law, using the loss distribution, the first heat, and the second heat.

[0041] Optionally, the loss determination module is specifically used to perform differential processing based on the non-uniform loss model to obtain a differential structure; and to obtain the loss distribution of the capacitor based on the differential structure.

[0042] Optionally, the loss determination module is specifically used to obtain the voltage differential equation and current differential equation of the capacitor based on the differential structure, wherein the voltage differential equation represents the plate voltage distribution of the capacitor and the current differential equation represents the plate current distribution of the capacitor; and to determine the total loss, plate loss, and dielectric loss of the capacitor based on the voltage differential equation and the current differential equation, wherein the total loss, plate loss, and dielectric loss constitute the loss distribution.

[0043] Optionally, the device further includes:

[0044] The relationship determination module is used to determine the correspondence between the capacitor's loss and the temperature field based on the loss distribution and the temperature field distribution.

[0045] Thirdly, a capacitor temperature field analysis device based on harmonic voltage is provided, including a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the following steps:

[0046] A non-uniform loss model is constructed based on the circuit parameters of the capacitor operating under harmonic voltage, wherein the circuit parameters are used to represent the state of the capacitor.

[0047] Based on the non-uniform loss model, the loss distribution of the capacitor is determined;

[0048] Based on the loss distribution and the corresponding thermodynamic model of the capacitor, the temperature field distribution of the capacitor is determined.

[0049] Fourthly, a computer-readable storage medium is provided, storing a computer program that, when executed by a processor, causes the processor to perform the following steps:

[0050] A non-uniform loss model is constructed based on the circuit parameters of the capacitor operating under harmonic voltage, wherein the circuit parameters are used to represent the state of the capacitor.

[0051] Based on the non-uniform loss model, the loss distribution of the capacitor is determined;

[0052] Based on the loss distribution and the corresponding thermodynamic model of the capacitor, the temperature field distribution of the capacitor is determined.

[0053] This application provides a method for analyzing the temperature field of a capacitor based on harmonic voltage. By constructing a non-uniform loss model based on the circuit parameters of the capacitor operating under harmonic voltage, and determining the loss distribution of the capacitor based on the non-uniform loss model, the temperature field distribution of the capacitor is determined based on the loss distribution and the corresponding thermodynamic model. By constructing a non-uniform loss model of the capacitor operating under harmonic voltage and obtaining the loss distribution of the capacitor, and then combining it with the corresponding thermodynamic model, the temperature field distribution of the capacitor under harmonic voltage can be accurately obtained, thereby improving the accuracy of the temperature field distribution and, consequently, the accuracy of the relationship between the temperature field and the capacitor loss. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] in:

[0056] Figure 1 A schematic flowchart illustrating a capacitor temperature field analysis method based on harmonic voltage provided in this application embodiment;

[0057] Figure 2 This is a schematic diagram of a non-uniform loss model provided in an embodiment of this application;

[0058] Figure 3 This application provides a schematic diagram of the differential structure in a capacitor.

[0059] Figure 4 This application provides a schematic flowchart for determining the temperature field distribution of a capacitor.

[0060] Figure 5 This application provides a schematic diagram of a thermodynamic model;

[0061] Figure 6 This is a schematic diagram of a capacitor-transformer oil heat exchange model provided in an embodiment of this application;

[0062] Figure 7 This application provides an internal structural diagram of a capacitor temperature field analysis device based on harmonic voltage. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] Power capacitors are important and commonly used devices in power systems. They play a role in energy storage and filtering during power transmission and distribution, reducing harmonics and voltage fluctuations in the system, and improving the efficiency and reliability of the power system. Their operating status is related to the safety and stability of the power grid.

[0065] Capacitors primarily consume reactive power when operating at mains frequency voltage. However, under the influence of high-order harmonic voltages and high transient voltages, their active power losses increase rapidly, significantly impacting the internal temperature of the capacitor. The dielectric loss of the capacitor insulation and the Joule loss on the metal plates constitute the main components of the capacitor's active power losses. Harmonic and transient voltage components in the power grid increase voltage amplitude; under the combined effect of high frequency and high amplitude, the dielectric loss of the capacitor insulation also increases. Furthermore, complex voltage waveforms increase the current flowing through the capacitor plates, thus increasing plate losses. The accumulation of active power losses in capacitors manifests as heating; increased losses lead to temperature rise, posing a serious challenge to the thermal stability and insulation life of the equipment.

[0066] Currently, most research on capacitor loss calculations focuses on using lumped parameter models, lacking a broadband loss model that considers plate current distribution and research on calculation methods for capacitor losses under non-periodic voltage. In studies of capacitor temperature field distribution, the thermal and temperature fields are often established through finite element analysis, but methods for analyzing the internal temperature field of capacitors by establishing the correlation between loss distribution and temperature field distribution still need improvement. The correlation between the internal temperature field distribution and loss distribution characteristics of capacitors, as well as voltage waveform and frequency, also requires further investigation.

[0067] Therefore, this application provides a method for analyzing the temperature field of a capacitor based on harmonic voltage. By constructing a non-uniform loss model based on the circuit parameters of the capacitor operating under harmonic voltage, and determining the loss distribution of the capacitor based on the non-uniform loss model, the temperature field distribution of the capacitor is determined based on the loss distribution and the corresponding thermodynamic model. By constructing a non-uniform loss model of the capacitor operating under harmonic voltage and obtaining the loss distribution of the capacitor, and then combining it with the corresponding thermodynamic model, the temperature field distribution of the capacitor under harmonic voltage can be accurately obtained, thereby improving the accuracy of the temperature field distribution and, consequently, the accuracy of the relationship between the temperature field and the capacitor loss.

[0068] Furthermore, based on the actual internal structure of the capacitor and the basic principles of capacitor loss calculation under harmonic voltage and heat transfer, this application provides an analysis of the temperature field of non-uniform capacitor loss under harmonic voltage. This solves the problems of difficult internal temperature measurement and high experimental testing time cost, and has high accuracy.

[0069] This application provides a method for analyzing the temperature field of a capacitor based on harmonic voltage, such as... Figure 1 As shown, Figure 1 The schematic flowchart illustrates a capacitor temperature field analysis method based on harmonic voltage, which is provided in an embodiment of this application. The method specifically includes the following steps:

[0070] Step 101: Construct a non-uniform loss model based on the circuit parameters of the capacitor operating under harmonic voltage.

[0071] The circuit parameters are used to represent the state of the capacitor. For example, the circuit parameters can be the voltage across the capacitor during operation, or the current flowing through the capacitor. This application does not specifically limit the circuit parameters.

[0072] Before determining the temperature field distribution of the capacitor, a non-uniform loss model can be constructed based on the circuit parameters corresponding to the capacitor during operation. This non-uniform loss model can then be used to determine the loss distribution of the capacitor in subsequent steps.

[0073] For example, see Figure 2 , Figure 2 This is a schematic diagram of a non-uniform loss model provided in an embodiment of this application, as shown below. Figure 2 As shown, the voltage across the capacitor is U0, and the current flowing through the capacitor can be i. Furthermore, the capacitor can include n differential structures, where n is a positive integer representing the number of differential structures. The voltage across the nth differential structure can be U0. n The current flowing through the nth differential structure can be i n .

[0074] Step 102: Determine the loss distribution of the capacitor based on the non-uniform loss model.

[0075] After establishing the non-uniform loss model, various losses that occur during the operation of the capacitor can be simulated based on the non-uniform loss model to determine the energy consumption of the capacitor through heat, so that the temperature field distribution of the capacitor can be generated in subsequent steps based on the loss distribution of the capacitor.

[0076] Optionally, a differential structure can be obtained by first differentiating the non-uniform loss model, and then the loss distribution of the capacitor can be obtained based on the differential structure. For example, Figure 2 As shown, the capacitor in the non-uniform loss model may include multiple differential structures. The embodiments of this application do not specifically limit the number of differential structures.

[0077] For example, see Figure 3 , Figure 3 This application provides a schematic diagram of the differential structure in a capacitor, as shown in the embodiment. Figure 3 As shown, the voltage at the input of the differential structure is U, and the voltage at the output is U+dU. m L is the resistance per unit length of the plates in a capacitor. m Let dU be the inductance per unit length of the plates in the capacitor, and R be the inductance per unit length of the plates. m and L m The voltage divider is formed by both input and output. The current in the input differential structure is I, and the current in the output differential structure is I+dI.

[0078] Furthermore, C0 represents the geometric capacitance of the capacitor, which exhibits a specific structure of insulation per unit length and lossless polarization. The current flowing through C0 is i. C0 R0 is the insulation resistance per unit length in the capacitor, and the current flowing through R0 is i. R0 .

[0079] Furthermore, per unit length, the differential structure can include a polarization loss branch consisting of k branches, and the kth branch can include a polarization capacitor C. k and polarization loss resistance R k .

[0080] Furthermore, in the process of obtaining the loss distribution of the capacitor based on the differential structure, we can start from the differential segments. First, based on the differential structure, we can obtain the voltage differential equation and current differential equation of the capacitor. Then, based on the voltage differential equation and current differential equation, we can further derive the voltage and current distribution characteristics of the capacitor, determine the total loss, plate loss and dielectric loss of the capacitor, and the total loss, plate loss and dielectric loss together constitute the loss distribution.

[0081] Among them, the voltage differential equation is used to represent the voltage distribution on the capacitor plates, and the current differential equation is used to represent the current distribution on the capacitor plates.

[0082] For example, we can first define a parameter Z, which represents the total impedance of the capacitor dielectric per unit length. This total impedance is composed of the main capacitance, insulation resistance, and polarization branches, and Z = R. m +jωL m R m L is the resistance per unit length of the plates in a capacitor. m Let ω be the inductance per unit length of the plates in the capacitor, j be the imaginary unit, and ω be the angular frequency.

[0083] Similarly, the total admittance of the capacitor dielectric per unit length can also be represented by the parameter G, which consists of the main capacitance, insulation resistance, and polarization branches. Where C0 represents the geometric capacitance per unit length of the capacitor, which is characterized by a specific insulating structure and lossless polarization; R0 is the insulation resistance per unit length of the capacitor; and C... i For polarization capacitor and R i There are k polarization loss resistors, k polarization capacitors, and k polarization loss resistors, where j is the imaginary unit and ω is the angular frequency.

[0084] Accordingly, from the differential structure in the capacitor equivalent model, we can obtain:

[0085]

[0086] Differentiating both sides of equations (1) and (2) again with respect to x, we get:

[0087]

[0088] Substituting equations (1) and (2) into equations (3) and (4) and simplifying, we can obtain... Differential equation with respect to x:

[0089]

[0090]

[0091] Solve equations (5) and (6) and substitute the boundary conditions when x = 0, when, we can obtain The analytical expression of is as follows:

[0092]

[0093] In equations (1) to (7), can be the voltage differential equation of the capacitor, can be the current differential equation of the capacitor. Z represents the total impedance of the capacitor dielectric per unit length, G represents the total admittance of the capacitor dielectric per unit length, x represents the length of the capacitor plate, l is a parameter corresponding to the length of the capacitor plate, A1 and A2 are both formula parameters, and e is the natural constant.

[0094] From equation (7), it can be seen that when the length of the capacitor plate is l and the voltage signal is input from one end of the capacitor, the analytical expression of the voltage and current distribution on the capacitor plate. It should be noted that in actual situations, the voltage input signal is often injected from the middle position of the plate. At this time, the capacitor can be divided into two parts, and the voltage and current distributions on both sides of the signal injection point can be calculated separately.

[0095] Furthermore, the losses of the capacitor mainly consist of plate losses and dielectric losses. Under the influence of harmonic voltage, the voltage and current distribution inside the capacitor will change, and the plate losses and dielectric losses will also increase accordingly. When calculating the losses, the total losses, plate losses, and dielectric losses at each position when the voltage is input from one side can be calculated according to the voltage differential equation and the current differential equation.

[0096] Among them, the plate losses and dielectric losses together constitute the total losses of the capacitor. Moreover, the plate losses are uneven in the capacitor, resulting in uneven distribution of the total losses in the capacitor.

[0097] For example, take a point x on the capacitor plate and calculate the loss density at the position of point x and the loss to the end of the capacitor plate (0 < x1 < l). The calculation expressions are as follows:

[0098] The plate loss density p m and the plate loss P m The expressions of are respectively:

[0099]

[0100] Dielectric loss density p d With dielectric loss P d The expressions are as follows:

[0101]

[0102] The expression for the total loss P is:

[0103]

[0104] In equations (8) to (10), R m I is the resistance per unit length of the plates in a capacitor. x Let represent the current at point x, where x represents the length of the capacitor plate at point x, and l is a parameter corresponding to the length of the capacitor plate. This represents the voltage differential equation corresponding to point x, where R0 is the insulation resistance per unit length in the capacitor, and C... i For polarization capacitor and R i There are k polarization loss resistors, k polarization capacitors and k polarization loss resistors. Re[] represents taking the real part of a complex number, j is the imaginary unit, ω is the angular frequency, and cos is the cosine function.

[0105] Step 103: Based on the loss distribution and the corresponding thermodynamic model of the capacitor, determine the temperature field distribution of the capacitor.

[0106] After obtaining the loss distribution of the capacitor, the heat transfer of the capacitor can be analyzed based on the constructed thermodynamic model corresponding to the capacitor. Thus, the temperature field distribution of the capacitor can be determined based on the analysis results, and the correspondence between the capacitor loss and the temperature field can be obtained.

[0107] Accordingly, see Figure 4 , Figure 4 This application provides a schematic flowchart for determining the temperature field distribution of a capacitor. Step 103 may include:

[0108] Step 1031: Construct the thermodynamic model corresponding to the capacitor.

[0109] In the thermodynamic model, both the first and second surfaces of the medium are equipped with plates, and the medium includes multiple temperature micro-elements. The first and second surfaces are parallel.

[0110] For example, see Figure 5 , Figure 5 A schematic diagram of a thermodynamic model provided in this application embodiment is shown below. Figure 5 As shown, the thermodynamic model consists of a medium and plates, with the plates distributed on the upper and lower surfaces of the medium. Furthermore, the medium can include multiple temperature micro-elements. Figure 5(The white area in the image). The temperature on the left side of this temperature element is T. d (x), the temperature on the right side of the temperature element is T. d (x+dx), where the temperatures on both sides of the infinitesimal element are T. m (x), Q1 represents the heat transferred from the right side of the temperature element to the left side via thermal conduction, Q2 represents the heat transferred from the upper and lower plates of the temperature element to the temperature element via thermal conduction, p d p is the dielectric loss density. m This represents the loss density of the two electrode plates.

[0111] Step 1032: Based on the loss distribution and combined with the temperature element, generate the temperature field distribution of the capacitor.

[0112] After obtaining the loss distribution of the capacitor, the temperature field distribution of the capacitor can be derived by combining the temperature infinitesimal elements in the thermodynamic model. This temperature field distribution can include: the dielectric temperature field distribution and the plate temperature field distribution. The dielectric temperature field distribution represents the temperature distribution of the dielectric, and the plate temperature field distribution represents the temperature distribution of the plates.

[0113] Optionally, the first heat transferred by the medium in the first direction can be determined based on the plate loss density of the plates in the thermodynamic model, and the second heat transferred by the medium in the second direction can be determined based on the medium loss density of the medium. Thus, the temperature field distribution can be generated based on the first heat and the second heat.

[0114] The first direction is the direction from the first face to the second face, and the second direction is perpendicular to the first direction.

[0115] Furthermore, in the process of generating the plate temperature field distribution, the medium temperature field distribution can be generated first based on the first heat and the second heat, and then the medium boundary temperature can be obtained by calculation based on the loss distribution, the first heat and the second heat. Finally, the plate temperature field distribution can be generated based on the medium temperature field distribution and the medium boundary temperature.

[0116] Among them, the medium temperature field distribution is used to represent the temperature distribution of the medium.

[0117] For example, taking a temperature infinitesimal element as the research object, according to the law of conservation of energy, we can obtain:

[0118] p d ·dx=Q1+Q2 (11)

[0119] Taking the plates on the upper and lower sides of the temperature element as the research object, and assuming that the upper and lower surfaces of the plates are thermal insulators, according to the law of conservation of energy, we can obtain:

[0120] p m ·dx=Q2 (12)

[0121] According to Fourier's law:

[0122] Q1 = k d ·A·[T d (x+dx)-T d (x)] (13)

[0123] Q2 = k m ·l·dx·[T m (x)-T d (x)] (14)

[0124] From the above formula, we can obtain:

[0125] k d ·A·[T d (x+dx)-T d [x]=p d ·dx+p m ·dx (15)

[0126] Divide both sides by k d ·A·dx =

[0127]

[0128] From this, the temperature field distribution T of the medium can be obtained. d (x):

[0129]

[0130] And because:

[0131] Q2 = k m ·l·dx·[T m (x)-T d [x]=p m ·dx (18)

[0132] From this, the temperature field distribution T of the electrode can be obtained. m (x):

[0133]

[0134] In equations (11) to (19), dx represents the size corresponding to the temperature element, Q1 represents the heat transferred from the right side of the temperature element to the left side by thermal conduction, Q2 represents the heat transferred from the upper and lower plates of the temperature element to the temperature element by thermal conduction, and p d p is the dielectric loss density. m k represents the loss density of the two plates. d k mT is a proportionality coefficient characterizing the thermal conductivity of the dielectric and electrode materials; A is the cross-sectional area of ​​the electrode perpendicular to the paper; l is the radial length perpendicular to the paper; x represents the length of the capacitor electrode corresponding to point x (i.e., the temperature element); T d (x) represents the temperature to the left of the temperature element, T d (x+dx) represents the temperature on the right side of the temperature element, T m (x) represents the temperatures above and below the temperature element, T d (0) represents the dielectric boundary temperature of the capacitor.

[0135] It should be noted that in the process of calculating the medium boundary temperature, the medium boundary temperature can be obtained by using the heat convection formula and Stefan's law, through loss distribution, first heat and second heat.

[0136] For example, see Figure 6 , Figure 6 This application provides a schematic diagram of a capacitor-transformer oil heat exchange model, as shown in the embodiment. Figure 6 As shown, the inside of a capacitor is usually composed of multiple capacitor cores connected in parallel and series, with the upper and lower surfaces of adjacent capacitor cores tightly fitted together.

[0137] In the following analysis, a capacitor core located at the center of the capacitor is taken as the research object. Considering the actual situation of the capacitor element, the upper and lower surfaces of the core are set to be thermally insulated. Its heat dissipation path is only through the curved parts on the left and right sides of the core. There are thermal convection and thermal radiation phenomena between these parts and the insulating oil.

[0138] Taking the capacitor boundary as the research object, according to the law of conservation of energy, the total active power loss generated by the capacitor is equal to the energy output by the capacitor to the transformer oil in the form of thermal convection and thermal radiation. From the thermal convection formula and the Stefan-Boltzmann law, we can obtain:

[0139] P = h[T] d (0)-T oil ]+εAσ b [T d (0)] 4 (20)

[0140] In the formula, P is the total loss of the capacitor, h is the convective heat transfer coefficient, ε is the emissivity of the capacitor surface, A is the radiative surface area of ​​the capacitor, and σ b T is the Stefan-Boltzmann constant. oil T represents the transformer oil temperature. d (0) represents the dielectric boundary temperature of the capacitor.

[0141] Accordingly, given the total loss P, the convective heat transfer coefficient h, the emissivity ε of the capacitor surface, the radiative surface area A of the capacitor, and the transformer oil temperature T...oil In this case, the dielectric boundary temperature T of the capacitor can be solved. d (0).

[0142] Step 104: Determine the correspondence between capacitor loss and temperature field based on loss distribution and temperature field distribution.

[0143] After obtaining the temperature field distribution and loss distribution of the capacitor, the temperature field distribution and loss distribution can be studied according to the different lengths of the capacitor plates, and the correspondence between the capacitor loss and the temperature field can be obtained.

[0144] In summary, the capacitor temperature field analysis method based on harmonic voltage provided in this application constructs a non-uniform loss model based on the circuit parameters of the capacitor operating under harmonic voltage. Based on this model, the loss distribution of the capacitor is determined. Then, based on this loss distribution and the corresponding thermodynamic model, the temperature field distribution of the capacitor is determined. By constructing a non-uniform loss model operating under harmonic voltage and obtaining the capacitor's loss distribution, combined with the corresponding thermodynamic model, the temperature field distribution of the capacitor under harmonic voltage can be accurately obtained, thereby improving the accuracy of the temperature field distribution and, consequently, the accuracy of the relationship between the temperature field and capacitor loss.

[0145] Furthermore, based on the actual internal structure of the capacitor and the basic principles of capacitor loss calculation under harmonic voltage and heat transfer, this application provides an analysis of the temperature field of non-uniform capacitor loss under harmonic voltage. This solves the problems of difficult internal temperature measurement and high experimental testing time cost, and has high accuracy.

[0146] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0147] Corresponding to the capacitor temperature field analysis method based on harmonic voltage described in the above embodiments, a capacitor temperature field analysis device based on harmonic voltage is also provided. For ease of explanation, only the parts related to the embodiments of this application are shown.

[0148] The device includes:

[0149] The model building module is used to construct a non-uniform loss model based on the circuit parameters of the capacitor operating under harmonic voltage. These circuit parameters are used to represent the state of the capacitor.

[0150] The loss determination module is used to determine the loss distribution of the capacitor based on the non-uniform loss model.

[0151] The temperature field determination module is used to determine the temperature field distribution of the capacitor based on the loss distribution and the corresponding thermodynamic model.

[0152] Optionally, the temperature field determination module is specifically used to construct the thermodynamic model corresponding to the capacitor. In the thermodynamic model, both the first and second surfaces of the dielectric are provided with plates. The dielectric includes multiple temperature micro-elements, and the first and second surfaces are parallel. Based on the loss distribution and combined with the temperature micro-elements, the temperature field distribution of the capacitor is generated.

[0153] Optionally, the temperature field determination module is further configured to determine, based on the plate loss density of the plate in the thermodynamic model, a first heat transferred by the medium in a first direction, the first direction being the direction from the first surface to the second surface; determine, based on the medium loss density of the medium, a second heat transferred by the medium in a second direction, the second direction being perpendicular to the first direction; and generate the temperature field distribution based on the first heat and the second heat.

[0154] Optionally, the temperature field distribution includes: a medium temperature field distribution and an electrode temperature field distribution, wherein the medium temperature field distribution is used to represent the temperature distribution of the medium, and the electrode temperature field distribution is used to represent the temperature distribution of the electrode.

[0155] The temperature field determination module is further specifically used to generate the medium temperature field distribution based on the first heat and the second heat; to calculate the medium boundary temperature based on the loss distribution, the first heat and the second heat; and to generate the electrode temperature field distribution based on the medium temperature field distribution and the medium boundary temperature.

[0156] Optionally, the temperature field determination module is also specifically used to calculate the medium boundary temperature based on the heat convection formula and Stefan's law, using the loss distribution, the first heat, and the second heat.

[0157] Optionally, the loss determination module is specifically used to perform differential processing based on the non-uniform loss model to obtain a differential structure; and based on the differential structure, to obtain the loss distribution of the capacitor.

[0158] Optionally, the loss determination module is specifically used to obtain the voltage differential equation and the current differential equation of the capacitor based on the differential structure. The voltage differential equation is used to represent the plate voltage distribution of the capacitor, and the current differential equation is used to represent the plate current distribution of the capacitor. Based on the voltage differential equation and the current differential equation, the total loss, plate loss and dielectric loss of the capacitor are determined. The total loss, plate loss and dielectric loss constitute the loss distribution.

[0159] Optionally, the device may also include:

[0160] The relationship determination module is used to determine the correspondence between the capacitor's loss and the temperature field based on the loss distribution and the temperature field distribution.

[0161] In summary, the capacitor temperature field analysis device based on harmonic voltage provided in this application constructs a non-uniform loss model based on the circuit parameters of the capacitor operating under harmonic voltage. Based on this model, the loss distribution of the capacitor is determined. Then, based on the loss distribution and the corresponding thermodynamic model, the temperature field distribution of the capacitor is determined. By constructing a non-uniform loss model operating under harmonic voltage and obtaining the capacitor's loss distribution, combined with the corresponding thermodynamic model, the temperature field distribution of the capacitor under harmonic voltage can be accurately obtained, thereby improving the accuracy of the temperature field distribution and, consequently, the accuracy of the relationship between the temperature field and capacitor loss.

[0162] Figure 7 This application provides an internal structural diagram of a capacitor temperature field analysis device based on harmonic voltage. This device can be a terminal or a server. Figure 7 As shown, the capacitor temperature field analysis device based on harmonic voltage includes a processor, a memory, and a network interface connected via a system bus. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and may also store a computer program. When executed by the processor, this computer program enables the processor to implement a capacitor temperature field analysis method based on harmonic voltage. The internal memory may also store a computer program, which, when executed by the processor, enables the processor to implement the capacitor temperature field analysis method based on harmonic voltage. Those skilled in the art will understand that... Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0163] In one embodiment, a capacitor temperature field analysis device based on harmonic voltage is provided, including a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the following steps:

[0164] A non-uniform loss model is constructed based on the circuit parameters of the capacitor operating under harmonic voltage, wherein the circuit parameters are used to represent the state of the capacitor.

[0165] Based on the non-uniform loss model, the loss distribution of the capacitor is determined;

[0166] Based on the loss distribution and the corresponding thermodynamic model of the capacitor, the temperature field distribution of the capacitor is determined.

[0167] By constructing a non-uniform loss model operating under harmonic voltage, the loss distribution of the capacitor can be obtained. Combined with the corresponding thermodynamic model of the capacitor, the temperature field distribution of the capacitor under harmonic voltage can be accurately obtained, thereby improving the accuracy of the temperature field distribution and, consequently, the accuracy of the relationship between the temperature field and the capacitor loss.

[0168] In one embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, causes the processor to perform the following steps:

[0169] A non-uniform loss model is constructed based on the circuit parameters of the capacitor operating under harmonic voltage, wherein the circuit parameters are used to represent the state of the capacitor.

[0170] Based on the non-uniform loss model, the loss distribution of the capacitor is determined;

[0171] Based on the loss distribution and the corresponding thermodynamic model of the capacitor, the temperature field distribution of the capacitor is determined.

[0172] By constructing a non-uniform loss model operating under harmonic voltage, the loss distribution of the capacitor can be obtained. Combined with the corresponding thermodynamic model of the capacitor, the temperature field distribution of the capacitor under harmonic voltage can be accurately obtained, thereby improving the accuracy of the temperature field distribution and, consequently, the accuracy of the relationship between the temperature field and the capacitor loss.

[0173] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0174] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0175] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method of capacitor temperature field analysis based on harmonic voltage, characterized by, The method comprises: constructing a non-uniform loss model according to circuit parameters of the capacitor when the capacitor operates based on a harmonic voltage, the circuit parameters being used to represent a state of the capacitor; determining a loss distribution of the capacitor according to the non-uniform loss model; determining a temperature field distribution of the capacitor according to the loss distribution and a corresponding thermodynamic model of the capacitor; the determining of the temperature field distribution of the capacitor according to the loss distribution and the corresponding thermodynamic model of the capacitor comprises: constructing the corresponding thermodynamic model of the capacitor, a first face and a second face of a medium in the thermodynamic model are both provided with an electrode plate, the medium comprises a plurality of temperature elements, and the first face and the second face are parallel; generating the temperature field distribution of the capacitor according to the loss distribution and the temperature elements; the generating of the temperature field distribution of the capacitor according to the loss distribution and the temperature elements comprises: determining a first heat transferred by the medium in a first direction according to an electrode plate loss density of the electrode plate in the thermodynamic model, the first direction being a direction from the first face to the second face; determining a second heat transferred by the medium in a second direction according to a medium loss density of the medium, the second direction being perpendicular to the first direction; generating the temperature field distribution according to the first heat and the second heat.

2. The harmonic voltage-based capacitor temperature field analysis method of claim 1, wherein, the temperature field distribution comprises a medium temperature field distribution and an electrode plate temperature field distribution, the medium temperature field distribution being used to represent a temperature distribution of the medium, and the electrode plate temperature field distribution being used to represent a temperature distribution of the electrode plate; the generating of the temperature field distribution according to the first heat and the second heat comprises: generating the medium temperature field distribution according to the first heat and the second heat; calculating a medium boundary temperature of the medium according to the loss distribution, the first heat and the second heat; generating the electrode plate temperature field distribution according to the medium temperature field distribution and the medium boundary temperature.

3. The harmonic voltage-based capacitor temperature field analysis method of claim 2, wherein, the calculating of the medium boundary temperature of the medium according to the loss distribution, the first heat and the second heat comprises: calculating the medium boundary temperature of the medium according to a heat convection formula and a Stefan law through the loss distribution, the first heat and the second heat.

4. The harmonic voltage-based capacitor temperature field analysis method of claim 1, wherein, the determining of the loss distribution of the capacitor according to the non-uniform loss model comprises: differentially processing the non-uniform loss model to obtain a differential structure; obtaining the loss distribution of the capacitor according to the differential structure.

5. The harmonic voltage-based capacitor temperature field analysis method of claim 4, wherein, the obtaining of the loss distribution of the capacitor according to the differential structure comprises: obtaining a voltage differential equation and a current differential equation of the capacitor according to the differential structure, the voltage differential equation being used to represent an electrode plate voltage distribution of the capacitor, and the current differential equation being used to represent an electrode plate current distribution of the capacitor; According to the voltage differential equation and the current differential equation, total loss, plate loss and dielectric loss of the capacitor are determined, and the total loss, the plate loss and the dielectric loss constitute the loss distribution.

6. The harmonic voltage-based capacitor temperature field analysis method according to any one of claims 1 to 5, characterized in that, After the temperature field distribution of the capacitor is determined according to the loss distribution and the corresponding thermodynamic model of the capacitor, the method further comprises: According to the loss distribution and the temperature field distribution, a corresponding relationship between the loss and the temperature field of the capacitor is determined.

7. A harmonic voltage-based capacitor temperature field analysis device, characterized by, The capacitor temperature field analysis device based on harmonic voltage comprises a memory and a processor, the memory stores a computer program, and the computer program is executed by the processor to enable the processor to execute the steps of the capacitor temperature field analysis method based on harmonic voltage in any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that, The computer program is stored and executed by the processor to enable the processor to execute the steps of the capacitor temperature field analysis method based on harmonic voltage in any one of claims 1 to 6.

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