Extra-high voltage converter transformer insulation life prediction method, equipment and medium

Abstract

The invention provides a method and equipment for predicting the insulation life of an extra-high voltage converter transformer, and a medium, and relates to the technical field of transformer fault diagnosis and state evaluation. The method comprises the following steps: performing high-reduction-degree simulation modeling on the extra-high voltage converter transformer to obtain a simulation model; on the basis of the equivalent B-H curve of converting the time domain into the frequency domain, simulating B-H characteristics of a nonlinear ferromagnetic material to carry out transformer leakage flux distribution frequency domain calculation on the simulation model to obtain a first calculation result; on the basis of the first calculation result and loss influence data of the skin effect on winding harmonic eddy-current loss, calculating loss of the transformer under harmonic influence to obtain a second calculation result; and based on the second calculation result, taking the fundamental wave loss as excitation, calculating hot spot distribution of the transformer under harmonic waves or rated working conditions, and predicting the insulation life of the transformer under the influence of the harmonic waves. According to the method, the efficiency of frequency domain simulation calculation and the accuracy of a correction result are improved, the service life of equipment is prolonged, and the operation and maintenance cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer fault diagnosis and state evaluation, and particularly relates to a method, device and medium for predicting insulation life of an extra-high voltage converter transformer. BACKGROUND

[0002] Compared with AC power transmission, high voltage direct current (HVDC) and extra-high voltage direct current (EHVDC) transmission has advantages in long-distance and large-capacity power transmission and power grid interconnection, such as lower line investment, flexible operation, no limitation of power system synchronous operation stability, high controllability, and smaller line charging power. The converter transformer is a core component of HVDC transmission. However, in actual operation, a large amount of harmonics is generated in the process of AC-DC conversion of the converter transformer, which will affect the leakage magnetic field, loss and temperature rise of the converter transformer, and ultimately affect the thermal life of the converter transformer. Therefore, it is of great significance to consider the influence of harmonics on the thermal insulation life of the converter transformer under actual working conditions.

[0003] Generally, the converter transformer winding loss of the extra-high voltage converter transformer is calculated by using the frequency domain analysis method and the time domain analysis method respectively. By comparing and analyzing the calculation results of the two methods, it is found that the frequency domain analysis method is more suitable for actual production design, but the B-H characteristics of the nonlinear ferromagnetic material are not considered in the simulation process. Alternatively, a simplified calculation model of the converter transformer under the time-harmonic field is established by using the Magnet software, and the harmonic loss in the winding and metal structural parts is simulated and calculated by using the finite element method. However, the influence of the skin effect on the winding harmonic eddy current loss is ignored in the simulation process. It can be seen that the B-H curve is the core of electromagnetic simulation, which accurately represents the nonlinear characteristics of the magnetic material and directly affects the accuracy of magnetic field calculation, loss analysis and temperature rise prediction. Ignoring the nonlinear characteristics of the B-H curve will cause serious distortion of the electromagnetic simulation results. Compared with time domain simulation, frequency domain simulation can greatly save calculation time, and therefore has important advantages in complex modeling and simulation. However, the traditional frequency domain simulation method is difficult to accurately restore the nonlinear B-H characteristics of the ferromagnetic material.

[0004] In related technologies, the relative permeability of the ferromagnetic material is set to a constant in the calculation of the frequency domain simulation of the leakage magnetic loss, loss temperature and other parameters of the extra-high voltage converter transformer, and the nonlinear B-H characteristics of the material itself are ignored. Although the influence of the skin effect on the winding eddy current loss under harmonics has been analyzed, there is no systematic integration of the skin effect correction method in the electromagnetic simulation framework based on the effective B-H curve.

[0005] Therefore, there is an urgent need to provide a method for predicting the insulation life of an extra-high voltage converter transformer to solve the problem that the related art has not systematically integrated the skin effect correction method in the electromagnetic simulation framework based on the effective B-H curve. Summary of the Invention

[0006] The present invention addresses the problems of the prior art by providing a method, device, and medium for predicting the insulation life of ultra-high voltage converter transformers. Based on fundamental-wave magnetic flux leakage simulation of the converter transformer, an equivalent BH curve is used in the frequency-domain simulation process to restore the nonlinear BH characteristics of ferromagnetic materials. The method analyzes the thermal field distribution under harmonic influences, focusing on the impact of the skin effect on the winding harmonic eddy current losses of the ultra-high voltage converter transformer. The thermal life of the ultra-high voltage converter transformer is predicted using a thermal life calculation formula. Furthermore, the original harmonic losses are multiplied by a harmonic loss factor correction coefficient, improving the efficiency of the frequency-domain simulation calculation and the accuracy of the correction results. This method optimizes the maintenance plan for the ultra-high voltage converter transformer, extends the equipment life, reduces operation and maintenance costs, improves the operational reliability of the ultra-high voltage converter transformer, and provides support for equipment upgrades and grid security.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a method for predicting the insulation life of an ultra-high voltage converter transformer, the method comprising:

[0009] Use 3D modeling software to simulate the UHV converter transformer with high fidelity to obtain a simulation model;

[0010] Based on the equivalent BH curve converted from the time domain to the frequency domain, the BH characteristics of the nonlinear ferromagnetic material are simulated to perform frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model to obtain a first calculation result;

[0011] Calculating the loss of the UHV converter transformer under the influence of harmonics based on the first calculation result and the loss impact data of the skin effect on the winding harmonic eddy current loss to obtain a second calculation result;

[0012] Based on the second calculation result, calculating the hot spot distribution of the UHV converter transformer under harmonic operating conditions or rated operating conditions with the fundamental wave loss as an excitation;

[0013] The insulation life of the UHV converter transformer under the influence of harmonics is predicted based on the hot spot distribution.

[0014] In some embodiments, based on the first calculation result and the loss impact data of the skin effect on the winding harmonic eddy current loss, the loss of the ultra-high voltage converter transformer under the influence of harmonics is calculated to obtain a second calculation result, including:

[0015] Calculating fundamental wave losses of various components of the UHV converter transformer based on fundamental wave leakage magnetic flux of the UHV converter transformer; wherein the fundamental wave losses include winding DC resistance loss, winding eddy current loss, core loss, or structural component stray loss;

[0016] Based on the fundamental wave loss and the loss impact data of the skin effect on the winding harmonic eddy current loss, the harmonic losses of each component of the ultra-high voltage converter transformer are calculated using the harmonic loss calculation formula; wherein the harmonic losses include harmonic DC resistance loss, winding harmonic eddy current loss or harmonic structural component stray loss.

[0017] In some embodiments, after calculating the fundamental wave loss of each component of the UHV converter transformer based on the fundamental wave magnetic leakage of the UHV converter transformer, the method further includes:

[0018] According to the calculation result of the fundamental wave loss, parameters including harmonic order, harmonic current amplitude or frequency are introduced;

[0019] The loss values ​​of the main structure of the ultra-high voltage converter transformer at different harmonic orders are calculated respectively by using the harmonic loss calculation formula; wherein the main structure of the ultra-high voltage converter transformer includes an iron core, a winding, a magnetic shield or an oil tank structure.

[0020] In some embodiments, a high-fidelity simulation model is performed on the UHV converter transformer using 3D modeling software to obtain a simulation model, including:

[0021] Carry out true modeling according to the actual size of the main structure of the UHV converter transformer;

[0022] With respect to the secondary structure of the UHV converter transformer, corresponding simplification is performed on the basis of retaining the key electromagnetic characteristics of the secondary structure to establish a true three-dimensional simulation model with high restoration degree.

[0023] In some embodiments, the method further comprises:

[0024] Finite element simulation software is used to construct a magnetic field simulation model using the fundamental current of the ultra-high voltage converter transformer as an excitation source.

[0025] In some embodiments, the method further comprises:

[0026] Setting a simulated current direction for excitation according to the actual flow direction of the current in each winding of the ultra-high voltage converter transformer;

[0027] A frequency domain solver is used instead of a transient solver to quickly solve the UHV converter transformer.

[0028] In some embodiments, based on an equivalent BH curve converted from the time domain to the frequency domain, the BH characteristics of the nonlinear ferromagnetic material are simulated to perform frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model, and obtain a first calculation result, including:

[0029] Based on the energy equivalence principle, the conversion target corresponding to the input variable is set according to the type of the input variable;

[0030] Performing spectrum analysis on the input signal of the input variable by using Fast Fourier Transform (FFT), converting the input signal from the time domain to the frequency domain, and obtaining a converted input signal;

[0031] Extract the amplitude and phase of the fundamental component of the converted input signal, and retain the main harmonic components of the converted input signal to provide basic data for subsequent energy modeling and fitting through sine function;

[0032] Based on the definition relationship of magnetic energy density, an integral model describing the magnetization behavior of nonlinear ferromagnetic materials is established;

[0033] The electromagnetic energy within one cycle is solved using numerical methods to satisfy the energy conservation condition;

[0034] Taking the fundamental component in the frequency domain as the target, the amplitude and phase of the equivalent sine wave are adjusted to obtain a sinusoidal form variable that meets the requirements of frequency domain simulation and obtain the calculation result of the fundamental wave loss.

[0035] In some embodiments, adjusting the amplitude and phase of the equivalent sine wave with the fundamental component in the frequency domain as a target includes:

[0036] Taking the fundamental component in the frequency domain as the target, the amplitude and phase of the equivalent sine wave are adjusted through an iterative optimization algorithm;

[0037] When the amplitude and phase of the equivalent sine wave are equivalent to those of the original waveform in terms of energy distribution, the iterative operation is stopped.

[0038] In a second aspect, the present invention further provides a device for predicting the insulation life of an ultra-high voltage converter transformer, comprising:

[0039] The simulation modeling unit is configured to use three-dimensional modeling software to perform high-fidelity simulation modeling on the ultra-high voltage converter transformer to obtain a simulation model;

[0040] The first calculation unit is configured to simulate the BH characteristics of the nonlinear ferromagnetic material based on the equivalent BH curve converted from the time domain to the frequency domain, and perform frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model to obtain a first calculation result;

[0041] a second calculation unit configured to calculate, based on the first calculation result and skin effect loss influence data of winding harmonic eddy current loss, a loss of the UHV converter transformer under harmonic influence to obtain a second calculation result;

[0042] a hot spot distribution calculation unit configured to calculate, based on the second calculation result, a hot spot distribution of the UHV converter transformer under a harmonic working condition or a rated working condition with the fundamental wave loss as an excitation;

[0043] a prediction unit configured to predict, according to the hot spot distribution, an insulation life of the UHV converter transformer under harmonic influence.

[0044] In a third aspect, the present application further provides a computer device, which comprises:

[0045] at least one processor; and,

[0046] a memory in communication connection with the at least one processor; wherein,

[0047] the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the above-mentioned prediction method for the insulation life of the UHV converter transformer.

[0048] In a fourth aspect, the present application further provides a computer readable storage medium storing computer instructions for causing a computer to perform the above-mentioned prediction method for the insulation life of the UHV converter transformer.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] The present application provides a prediction method for the insulation life of the UHV converter transformer, which combines the influence of the actual harmonic environment on the loss, is based on the fundamental wave leakage magnetic simulation of the converter transformer, adopts equivalent B-H curves in the frequency domain simulation process to restore the nonlinear B-H characteristics of the ferromagnetic material, analyzes the thermal field distribution under the action of the harmonic in view of the influence of the skin effect on the winding harmonic eddy current loss of the UHV converter transformer, and predicts the thermal life of the UHV converter transformer by using a thermal life calculation formula. Moreover, the original harmonic loss is corrected by multiplying a harmonic loss factor correction coefficient, which improves the efficiency of the frequency domain simulation calculation and the accuracy of the correction result, optimizes the maintenance plan of the UHV converter transformer, prolongs the service life of the equipment, reduces the operation and maintenance cost, improves the operation reliability of the UHV converter transformer, and provides support for equipment upgrading and power grid safety. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1A flowchart of a method for predicting the insulation life of a UHV converter transformer provided in an embodiment of the present disclosure;

[0052] Figure 2 Temperature cloud diagram and temperature time domain variation diagram of the effective BH curve magnetization model provided by the embodiment of the present disclosure;

[0053] Figure 3 The temperature cloud map and temperature time domain variation map of the relative permeability magnetization model provided in the embodiment of the present disclosure;

[0054] Figure 4 A schematic diagram of a frequency domain calculation model provided in an embodiment of the present disclosure;

[0055] Figure 5 A schematic diagram of a time domain computing model provided in an embodiment of the present disclosure;

[0056] Figure 6 A schematic diagram of a calculation model under harmonic working conditions provided by an embodiment of the present disclosure;

[0057] Figure 7 A schematic diagram of a calculation model under rated operating conditions provided by an embodiment of the present disclosure;

[0058] Figure 8 A schematic diagram of the structure of a device for predicting the insulation life of an ultra-high voltage converter transformer provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0059] It is worth noting that the methods used in the present invention are all conventional methods unless otherwise specified; the raw materials and devices used are all conventional commercially available products, and their sources are not specifically limited unless otherwise specified.

[0060] See also Figure 1 , Figure 1 A flowchart of a method for predicting the insulation life of a UHV converter transformer provided in an embodiment of the present disclosure is provided. The method for predicting the insulation life of a UHV converter transformer provided in an embodiment of the present disclosure includes the following steps:

[0061] S101. Use three-dimensional modeling software to perform high-fidelity simulation modeling on the ultra-high voltage converter transformer to obtain a simulation model.

[0062] This disclosed embodiment uses 3D modeling software to create a highly realistic 3D model of a ±800kV UHV converter transformer, comprehensively covering its core structural and functional components. Specifically, this includes detailed modeling of the core, windings, fuel tank, and other main structures; precise modeling of key structural components such as clamps and pull plates; and detailed modeling of protective devices such as the magnetic shielding of the winding lobes and fuel tank.

[0063] S102 , based on an equivalent BH curve converted from the time domain to the frequency domain, simulating the BH characteristics of the nonlinear ferromagnetic material, performing frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model to obtain a first calculation result.

[0064] Finite element simulation software is used to construct a magnetic field simulation model with the fundamental current of the UHV converter transformer as the excitation source. The equivalent BH curve converted from time domain to frequency domain is used to simulate the BH characteristics of nonlinear ferromagnetic materials to accurately solve the magnetic field distribution inside the UHV converter transformer.

[0065] The disclosed embodiment utilizes finite element simulation software and introduces an energy conservation mechanism to construct an equivalent BH curve model in the frequency domain. This significantly reduces the simulation time cost while achieving high-fidelity restoration of the response characteristics of nonlinear ferromagnetic materials. This effectively overcomes the problem that traditional frequency domain simulation has difficulty restoring the nonlinear ferromagnetic material response characteristics of the equivalent BH curve.

[0066] S103. Based on the first calculation result and the loss impact data of the skin effect on the winding harmonic eddy current loss, calculate the loss of the ultra-high voltage converter transformer under the influence of harmonics to obtain a second calculation result.

[0067] S104. Based on the second calculation result, with the fundamental wave loss as an excitation, calculate the hot spot distribution of the UHV converter transformer under harmonic operating conditions or rated operating conditions.

[0068] Alternatively, the formula using the fundamental wave loss of each component of the UHV converter transformer under the action of harmonics as the excitation is as follows:

[0069]

[0070] Wherein, Q represents the heat loss density of the UHV converter transformer; P0 represents the loss of the corresponding components of the UHV converter transformer; V represents the volume of the corresponding components of the UHV converter transformer;

[0071] The heat transfer formula between solid and fluid is as follows:

[0072]

[0073] Where P represents the material density; C p represents specific heat capacity; T represents temperature; u represents fluid velocity field; k represents thermal conductivity; Q represents heat source term; t represents time; Represents the temperature gradient.

[0074] The disclosed embodiment utilizes finite element simulation software to perform multi-physics field simulation, couples the solid heat transfer and fluid heat transfer physical fields with the magnetic field, and uses the losses of various components of the UHV converter transformer (including core loss, winding loss, magnetic shielding loss, and tank stray loss) as thermal excitation sources to calculate the hotspot distribution of the UHV converter transformer.

[0075] S105: Predicting the insulation life of the UHV converter transformer under the influence of harmonics based on the hotspot distribution.

[0076] Based on the calculation results of hot spot distribution of UHV converter transformer under harmonics and combined with the Arrhenius insulation material thermal aging calculation formula, the thermal life of winding insulation materials is predicted.

[0077] In some embodiments, the calculation formula for the insulation life of the UHV converter transformer under the influence of harmonics is as follows:

[0078]

[0079] Where L represents the insulation life of the UHV converter transformer winding under the influence of harmonics; A represents the pre-exponential factor; Ea represents the activation energy; k B represents the Boltzmann constant; T represents the hot spot temperature of the UHV converter transformer winding.

[0080] The embodiment of the present disclosure predicts the insulation life of the UHV converter transformer under the influence of harmonics based on the hot spot distribution of the UHV converter transformer under harmonic working conditions.

[0081] The present invention provides a method for predicting the insulation life of a UHV converter transformer. i Integrating the impact of actual harmonic environments on losses, and based on fundamental flux leakage simulation of UHV converter transformers, this study employed equivalent BH curves in frequency-domain simulations to replicate the nonlinear BH characteristics of ferromagnetic materials. The study analyzed the impact of the skin effect on the harmonic eddy current losses in the UHV converter transformer windings, analyzed the thermal field distribution under harmonic influence, and used thermal life calculation formulas to predict the thermal life of the UHV converter transformer. Furthermore, a harmonic loss correction factor was multiplied by the original harmonic losses. This improved the efficiency of the frequency-domain simulation calculations and the accuracy of the correction results, optimizing the maintenance plan for the UHV converter transformers, extending equipment life, reducing operation and maintenance costs, and improving the operational reliability of the UHV converter transformers. This also provided support for equipment upgrades and grid security.

[0082] In some embodiments, based on the first calculation result and the loss impact data of the skin effect on the winding harmonic eddy current loss, the loss of the ultra-high voltage converter transformer under the influence of harmonics is calculated to obtain a second calculation result, including:

[0083] Calculating fundamental wave losses of various components of the UHV converter transformer based on fundamental wave leakage magnetic flux of the UHV converter transformer; wherein the fundamental wave losses include winding DC resistance loss, winding eddy current loss, core loss, or structural component stray loss;

[0084] Based on the fundamental wave loss and the loss impact data of the skin effect on the winding harmonic eddy current loss, the harmonic losses of each component of the ultra-high voltage converter transformer are calculated using the harmonic loss calculation formula; wherein the harmonic losses include harmonic DC resistance loss, winding harmonic eddy current loss or harmonic structural component stray loss.

[0085] Optionally, based on the fundamental wave leakage magnetic flux of the UHV converter transformer, the fundamental wave loss of each component of the UHV converter transformer is calculated using the following formula:

[0086] P i =I 2 ·R;

[0087] Among them, P i It represents the resistance loss of each harmonic component of the winding; I represents the effective value of each fundamental current component; R represents the winding resistance of the UHV converter transformer.

[0088] The total resistance loss of the UHV converter transformer is expressed by the following calculation formula:

[0089]

[0090] Where P represents the total resistance loss.

[0091] Alternatively, since harmonics have little effect on the core loss of the UHV converter transformer, only the fundamental wave loss of the core is calculated. The calculation formula is as follows:

[0092]

[0093] Among them, Q represents the fundamental wave loss of the core; K h It represents the fundamental wave loss calculation coefficient of the core, which is usually taken as 1000; f represents the fundamental wave frequency, which is usually taken as 50Hz; B represents the magnetic induction intensity of the core.

[0094] Optionally, the calculation formula for the stray loss of structural components under fundamental wave is as follows:

[0095]

[0096] Among them, P SE1 represents the stray loss of the structural parts under the fundamental wave; σ represents the electrical conductivity; E represents the electric field strength; μ0 represents the vacuum magnetic permeability; μ1 represents the magnetic loss factor of the nonlinear ferromagnetic material; ω represents the angular frequency; H represents the magnetic field strength.

[0097] Optionally, the calculation formula for each harmonic loss of the structural component is as follows:

[0098]

[0099] Among them, P SEi Indicates the stray loss of structural components under each harmonic; P SE1 Indicates the stray loss of structural components under fundamental wave; I h Indicates the effective value of the current corresponding to the hth harmonic; F h is the hth harmonic frequency; I1 is the rated current effective value; F1 represents the power frequency, which is 50Hz.

[0100] Optionally, in the embodiment of the present disclosure, the stray loss of the structural components under the fundamental wave is first calculated, and then the stray loss of the structural components under each harmonic is calculated based on the fundamental wave loss. Finally, the stray loss of the structural components under each harmonic is summed up using a summation calculation formula to obtain the total harmonic stray loss of the structural components. The calculation formula is as follows:

[0101]

[0102] Among them, P SEi It represents the stray loss of structural components under each harmonic; P represents the total harmonic stray loss of structural components.

[0103] Optionally, the calculation formula for the winding fundamental wave eddy current loss is as follows:

[0104]

[0105] Among them, P WE1 represents the fundamental eddy current loss of the winding; ρ represents the resistivity of the winding; B represents the magnetic induction intensity of the winding; ω represents the angular frequency; R i Indicates the distance from the i-th unit to the center line of the core; S i represents the area of ​​the i-th unit.

[0106] Optionally, based on the fundamental wave loss, the harmonic loss calculation formula is used and the loss impact data of the skin effect on the winding harmonic eddy current loss is considered to calculate the harmonic loss of each component of the UHV converter transformer, using the following calculation formula:

[0107]

[0108] Among them, P WEi Indicates the eddy current loss of the UHV converter transformer winding under this harmonic; I h Indicates the effective value of the current corresponding to the hth harmonic; F h Indicates the hth harmonic frequency; I1 indicates the effective value of the rated current; F1 indicates the power frequency, which is 50Hz.

[0109] Optionally, in the process of solving the winding harmonic eddy current loss, considering the influence of the actual skin effect on the winding harmonic eddy current loss, the embodiment of the present disclosure adopts an accurate calculation method based on a skin correction factor, by establishing a quantitative relationship between the skin depth and the size of the conductor, a dynamic correction factor F related to the frequency is introduced, and the non-uniformity of the current density distribution and the harmonic superposition effect are comprehensively considered to correct the winding harmonic eddy current loss:

[0110]

[0111] ξ=T / δ

[0112]

[0113]

[0114] Wherein, F represents the skin correction factor; T represents the height of the conductor; p represents the resistivity of the conductor material; μ represents the magnetic permeability of the conductor material; f represents the fundamental frequency; h represents the harmonic order; δ1, δ respectively represent the skin depth of the conductor under the fundamental frequency and the harmonic; and ξ represents a defined variable.

[0115] Optionally, the total winding eddy current loss is represented by the following calculation formula:

[0116]

[0117] Wherein, P represents the total winding eddy current loss of the UHV converter transformer; P WEi represents the winding eddy current loss of the UHV converter transformer under the harmonic.

[0118] In some embodiments, after calculating the fundamental loss of each component of the UHV converter transformer according to the fundamental leakage magnetic flux of the UHV converter transformer, the method further comprises:

[0119] According to the calculation result of the fundamental loss, introducing parameters containing harmonic order, harmonic current amplitude or frequency;

[0120] Calculating the loss value of the main structure of the UHV converter transformer under different harmonic orders by the harmonic loss calculation formula; wherein the main structure of the UHV converter transformer includes the core, winding, magnetic shield or oil tank structure.

[0121] In some embodiments, a three-dimensional modeling software is used to simulate the UHV converter transformer with high fidelity to obtain a simulation model, including:

[0122] According to the actual size of the main structure of the UHV converter transformer, a true model is established;

[0123] With respect to the secondary structure of the UHV converter transformer, corresponding simplification is performed on the basis of retaining the key electromagnetic characteristics of the secondary structure to establish a true three-dimensional simulation model with high restoration degree.

[0124] Optionally, a high-fidelity true-to-life three-dimensional simulation model is established according to the actual dimensions of each component of the UHV converter transformer, wherein the main structures such as the core and winding are modeled at a 1:1 ratio, and the remaining secondary structures such as pull plates, clamps, oil tank magnetic shielding and lung lobe magnetic shielding are moderately simplified while retaining key electromagnetic characteristics to achieve high-fidelity true-to-life simulation modeling.

[0125] In some embodiments, the method further comprises:

[0126] Finite element simulation software is used to construct a magnetic field simulation model using the fundamental current of the ultra-high voltage converter transformer as an excitation source.

[0127] In some embodiments, the method further comprises:

[0128] Setting a simulated current direction for excitation according to the actual flow direction of the current in each winding of the ultra-high voltage converter transformer;

[0129] A frequency domain solver is used instead of a transient solver to quickly solve the UHV converter transformer.

[0130] In some embodiments, based on an equivalent BH curve converted from the time domain to the frequency domain, the BH characteristics of the nonlinear ferromagnetic material are simulated to perform frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model, and obtain a first calculation result, including:

[0131] Based on the energy equivalence principle, the conversion target corresponding to the input variable is set according to the type of the input variable;

[0132] Performing spectrum analysis on the input signal of the input variable by using Fast Fourier Transform (FFT), converting the input signal from the time domain to the frequency domain, and obtaining a converted input signal;

[0133] Extract the amplitude and phase of the fundamental component of the converted input signal, and retain the main harmonic components of the converted input signal to provide basic data for subsequent energy modeling and fitting through sine function;

[0134] Based on the definition relationship of magnetic energy density, an integral model describing the magnetization behavior of nonlinear ferromagnetic materials is established;

[0135] The electromagnetic energy within one cycle is solved using numerical methods to satisfy the energy conservation condition;

[0136] The amplitude and phase of the equivalent sinusoidal wave are adjusted to obtain a sinusoidal form variable satisfying the frequency domain simulation requirement, and a calculation result of the fundamental loss is obtained.

[0137] Optionally, if the magnetic induction intensity B(t) is an input variable, the equivalent magnetic field intensity H ep needs to be calculated, and if the magnetic field intensity H(t) is an input variable, the equivalent magnetic induction intensity B ep needs to be calculated. The conversion process is based on the energy equivalence principle, and ensures that the energy contained in the output variable is consistent with the original variable.

[0138] Optionally, based on the magnetic energy density definition relationship, an integral model describing the magnetization behavior of the nonlinear ferromagnetic material is established, and a numerical method is used to solve the electromagnetic energy in a period, so that the energy conservation condition is established.

[0139] Optionally, the fundamental component in the frequency domain is targeted, and the amplitude and phase of the equivalent sinusoidal wave are adjusted by an iterative optimization algorithm, so that the equivalent sinusoidal wave is equivalent to the original waveform in energy distribution, so that a sinusoidal form variable Bep(t) or Hep(t) satisfying the frequency domain simulation requirement is obtained.

[0140]

[0141] Wherein, B ep represents the equivalent magnetic induction intensity in the frequency domain; H ep represents the equivalent magnetic field intensity in the frequency domain; B represents the magnetic induction intensity; H represents the magnetic field intensity; represents the conjugate of the magnetic field intensity; represents the conjugate of the magnetic induction intensity. The embodiments of the present disclosure utilize the finite element simulation software to perform magnetic field simulation calculation by taking the fundamental current of the ultra-high voltage converter transformer as excitation, and consider the B-H characteristics of the nonlinear ferromagnetic material by the method of equivalent B-H curve in the frequency domain to more accurately obtain the leakage magnetic distribution of the whole ultra-high voltage converter transformer.

[0142] In some embodiments, the amplitude and phase of the equivalent sinusoidal wave are adjusted by targeting the fundamental component in the frequency domain, including:

[0143] The amplitude and phase of the equivalent sinusoidal wave are adjusted by targeting the fundamental component in the frequency domain through an iterative optimization algorithm.

[0144] When the amplitude and phase of the equivalent sinusoidal wave are equivalent to the original waveform in energy distribution, the iterative operation is stopped.

[0145] A method for predicting the insulation life of an ultra-high voltage converter transformer provided in an embodiment of the present disclosure has broad application prospects in engineering practice. Combining the impact of an actual harmonic environment on losses and based on fundamental magnetic flux leakage simulation of the ultra-high voltage converter transformer, while retaining the advantage of rapid frequency domain simulation calculations, the method ensures the accuracy of insulation life prediction results based on the equivalent BH curve method. The method considers the influence of the skin effect on winding harmonic eddy current losses, analyzes the thermal field distribution under the action of harmonics, and uses a thermal life calculation formula to predict the thermal life of the ultra-high voltage converter transformer. This method helps to optimize maintenance plans, extend equipment life, reduce operation and maintenance costs, improve operational reliability, and provide support for equipment upgrades and grid security.

[0146] See also Figure 2 、 Figure 3 As shown, Figure 2 The temperature cloud diagram and temperature time domain variation diagram of the effective BH curve magnetization model provided by the embodiment of the present disclosure are: Figure 3 The temperature cloud map and temperature time-domain variation diagram of the relative permeability magnetization model provided in the embodiments of the present disclosure are shown. The embodiments of the present disclosure use two magnetization models, the effective BH curve magnetization model and the relative permeability magnetization model, to calculate the three-dimensional model of the same ultra-high voltage converter transformer. During the simulation process, except for the difference in the magnetization model, the remaining materials, meshes, physical fields, and solver settings are the same. The hotspot temperature calculated for the effective BH curve magnetization model is 92.9 degrees Celsius, while the hotspot temperature calculated for the relative permeability magnetization model is 87.3 degrees Celsius. The hotspot temperature of the effective BH curve magnetization model is 5.6 degrees Celsius higher than that of the relative permeability magnetization model. The thermal life of the effective BH curve magnetization model is calculated to be 9.3 years, while the thermal life of the relative permeability magnetization model is calculated to be 14.6 years. The thermal life of the effective BH curve magnetization model is 5.3 years less than that of the relative permeability magnetization model. It can be seen from this that if the frequency domain calculation is performed using the ordinary relative permeability magnetization model, the thermal life margin of the winding may be overestimated, causing unnecessary losses to the equipment.

[0147] See also Figure 4 、 Figure 5 As shown, Figure 4 A schematic diagram of a frequency domain calculation model provided in an embodiment of the present disclosure, Figure 5 This is a schematic diagram of the time domain calculation model provided in an embodiment of the present disclosure. In the embodiment of the present disclosure, the magnetic field results calculated in the frequency domain and the losses simulated in the magnetic field calculated in the time domain are used as excitations and coupled with the temperature field simulation in the time domain. The settings of the excitation, material grid, etc. are exactly the same. The hot spot difference between the simulation results of the frequency domain calculation model and the time domain calculation model is small, only 1.2 degrees Celsius. The total time used for the frequency domain and time domain simulations are 323 minutes and 764 minutes respectively. The total time of the time domain simulation is 2.36 times that of the frequency domain simulation. It can be seen that the use of the frequency domain solver greatly saves simulation time.

[0148] See also Figure 6 、 Figure 7 As shown, Figure 6 This is a schematic diagram of a calculation model under harmonic conditions provided by an embodiment of the present disclosure. Figure 7 This is a schematic diagram of a calculation model under rated operating conditions provided by an embodiment of the present disclosure. This embodiment of the present disclosure compares the hotspot temperature of a UHV converter transformer operating under rated operating conditions (no harmonics) with the hotspot temperature of a UHV toroidal transformer operating under a harmonic operating condition. The comparison results show that the hotspot temperature of the UHV converter transformer under rated operating conditions (no harmonics) is 92.9 degrees Celsius, while the hotspot temperature of the UHV toroidal transformer under a harmonic operating condition is 87.6 degrees Celsius. The hotspot temperature under a harmonic operating condition is 5.3 degrees Celsius higher than that under rated operating conditions. The thermal life of the UHV converter transformer under rated operating conditions (no harmonics) is calculated to be 9.3 years, compared to 14.2 years for the UHV toroidal transformer under a harmonic operating condition. The thermal life of the effective BH curve magnetization model is 4.9 years shorter than that of the relative permeability magnetization model.

[0149] See also Figure 8 , Figure 8 This is a schematic diagram of the structure of a device for predicting the insulation life of a UHV converter transformer provided in an embodiment of the present disclosure. The device for predicting the insulation life of a UHV converter transformer provided in an embodiment of the present disclosure includes:

[0150] The simulation modeling unit 81 is configured to perform high-fidelity simulation modeling of the UHV converter transformer using three-dimensional modeling software to obtain a simulation model;

[0151] The first calculation unit 82 is configured to simulate the BH characteristics of the nonlinear ferromagnetic material based on the equivalent BH curve converted from the time domain to the frequency domain, and perform frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model to obtain a first calculation result;

[0152] A second calculation unit 83 is configured to calculate the loss of the UHV converter transformer under the influence of harmonics based on the first calculation result and the loss impact data of the skin effect on the winding harmonic eddy current loss, to obtain a second calculation result;

[0153] a hotspot distribution calculation unit 84 configured to calculate, based on the second calculation result and with the fundamental wave loss as an excitation, a hotspot distribution of the UHV converter transformer under harmonic operating conditions or rated operating conditions;

[0154] The prediction unit 85 is configured to predict the insulation life of the UHV converter transformer under the influence of harmonics according to the hot spot distribution.

[0155] The present invention further provides a computer device, comprising:

[0156] at least one processor; and,

[0157] a memory communicatively connected to the at least one processor; wherein,

[0158] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the above-mentioned method for predicting the insulation life of the ultra-high voltage converter transformer.

[0159] The present invention also provides a computer-readable storage medium, which stores computer instructions. The computer instructions are used to enable a computer to execute the above-mentioned method for predicting the insulation life of an ultra-high voltage converter transformer.

[0160] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for predicting the insulation life of a UHV converter transformer, characterized in that: The method comprises: Use 3D modeling software to simulate the UHV converter transformer with high fidelity to obtain a simulation model; Based on the equivalent BH curve converted from the time domain to the frequency domain, the BH characteristics of the nonlinear ferromagnetic material are simulated to perform frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model to obtain a first calculation result; Calculating the loss of the UHV converter transformer under the influence of harmonics based on the first calculation result and the loss impact data of the skin effect on the winding harmonic eddy current loss to obtain a second calculation result; Based on the second calculation result, calculating the hot spot distribution of the UHV converter transformer under harmonic operating conditions or rated operating conditions with the fundamental wave loss as an excitation; The insulation life of the UHV converter transformer under the influence of harmonics is predicted based on the hot spot distribution.

2. The method for predicting the insulation life of a UHV converter transformer according to claim 1, wherein: Based on the first calculation result and the loss impact data of the skin effect on the winding harmonic eddy current loss, the loss of the ultra-high voltage converter transformer under the influence of harmonics is calculated to obtain a second calculation result, including: Calculating fundamental wave losses of various components of the UHV converter transformer based on fundamental wave leakage magnetic flux of the UHV converter transformer; wherein the fundamental wave losses include winding DC resistance loss, winding eddy current loss, core loss, or structural component stray loss; Based on the fundamental wave loss and the loss impact data of the skin effect on the winding harmonic eddy current loss, the harmonic losses of each component of the ultra-high voltage converter transformer are calculated using the harmonic loss calculation formula; wherein the harmonic losses include harmonic DC resistance loss, winding harmonic eddy current loss or harmonic structural component stray loss.

3. The method for predicting the insulation life of a UHV converter transformer according to claim 2, wherein: After calculating the fundamental wave loss of each component of the UHV converter transformer based on the fundamental wave magnetic leakage of the UHV converter transformer, the method further includes: According to the calculation result of the fundamental wave loss, parameters including harmonic order, harmonic current amplitude or frequency are introduced; The loss values ​​of the main structure of the ultra-high voltage converter transformer at different harmonic orders are calculated respectively by using the harmonic loss calculation formula; wherein the main structure of the ultra-high voltage converter transformer includes an iron core, a winding, a magnetic shield or an oil tank structure.

4. The method for predicting the insulation life of a UHV converter transformer according to claim 1, wherein: Use 3D modeling software to simulate the UHV converter transformer with high fidelity, and obtain a simulation model including: Carry out true modeling according to the actual size of the main structure of the UHV converter transformer; With respect to the secondary structure of the UHV converter transformer, corresponding simplification is performed on the basis of retaining the key electromagnetic characteristics of the secondary structure to establish a true three-dimensional simulation model with high restoration degree.

5. The method for predicting the insulation life of a UHV converter transformer according to claim 4, characterized in that: The method further comprises: Finite element simulation software is used to construct a magnetic field simulation model using the fundamental current of the ultra-high voltage converter transformer as an excitation source.

6. The method for predicting the insulation life of a UHV converter transformer according to claim 5, characterized in that: The method further comprises: Setting a simulated current direction for excitation according to the actual flow direction of the current in each winding of the ultra-high voltage converter transformer; A frequency domain solver is used instead of a transient solver to quickly solve the UHV converter transformer.

7. The method for predicting the insulation life of a UHV converter transformer according to claim 1, wherein: Based on the equivalent BH curve converted from the time domain to the frequency domain, the BH characteristics of the nonlinear ferromagnetic material are simulated to perform frequency domain calculation of the leakage magnetic distribution of the ultra-high voltage converter transformer on the simulation model, and a first calculation result is obtained, including: Based on the energy equivalence principle, the conversion target corresponding to the input variable is set according to the type of the input variable; Performing spectrum analysis on the input signal of the input variable by using Fast Fourier Transform (FFT), converting the input signal from the time domain to the frequency domain, and obtaining a converted input signal; Extract the amplitude and phase of the fundamental component of the converted input signal, and retain the main harmonic components of the converted input signal to provide basic data for subsequent energy modeling and fitting through sine function; Based on the definition of magnetic energy density, an integral model is established to describe the magnetization behavior of nonlinear ferromagnetic materials; The electromagnetic energy within one cycle is solved using numerical methods to satisfy the energy conservation condition; Taking the fundamental component in the frequency domain as the target, the amplitude and phase of the equivalent sine wave are adjusted to obtain a sinusoidal form variable that meets the requirements of frequency domain simulation and obtain the calculation result of the fundamental wave loss.

8. The method for predicting the insulation life of a UHV converter transformer according to claim 7, characterized in that: Targeting the fundamental component in the frequency domain, adjust the amplitude and phase of the equivalent sine wave, including: Taking the fundamental component in the frequency domain as the target, the amplitude and phase of the equivalent sine wave are adjusted through an iterative optimization algorithm; When the amplitude and phase of the equivalent sine wave are equivalent to those of the original waveform in terms of energy distribution, the iterative operation is stopped.

9. A computer device, characterized in that: The computer device comprises: at least one processor; and, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method for predicting the insulation life of the ultra-high voltage converter transformer according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, which are used to enable a computer to execute the method for predicting the insulation life of an ultra-high voltage converter transformer according to any one of claims 1 to 8.

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