Method and device for determining winding stress of transformer winding, equipment and medium

Abstract

The invention discloses a winding stress determination method and device of a transformer winding, equipment and a medium, and relates to the field of power transformer winding vibration stress analysis, and the method comprises the steps: determining a harmonic current component under a harmonic current of each frequency corresponding to a transformer; determining a Young modulus corresponding to the harmonic current component under the harmonic current of each frequency, and determining an electromagnetic force related to the Young modulus and corresponding to the harmonic current of each frequency; temperatures corresponding to different harmonic current components under the harmonic currents with different frequencies are the same or different; the Young modulus at different temperatures is different; calculating the single winding mechanical stress of the harmonic current of each frequency based on the Young modulus, and calculating the total winding mechanical stress; calculating a single electromagnetic stress of the harmonic current of each frequency based on the electromagnetic force, and calculating a total electromagnetic stress; and calculating the sum of the total winding mechanical stress and the total electromagnetic stress to obtain the winding stress. And the winding stress under the action of different harmonic currents can be determined.

Description

Technical Field

[0001] The invention relates to the field of power transformer winding vibration stress analysis, and in particular to a method, device, equipment and medium for determining winding stress of a transformer winding. Background Art

[0002] At present, the harmonic problem caused by the "double high" characteristics of the new power system is becoming increasingly prominent, with serious increase in harmonic components, uncertain flow direction, and complex propagation mechanism. Harmonics have a significant impact on the safe operation of power equipment, and are prone to cause equipment overheating, increased vibration, accelerated equipment aging, and shortened equipment life. Therefore, it is of great significance to study the impact of harmonic current on the vibration characteristics of transformers.

[0003] Regarding the research on the stress distribution characteristics of transformer windings, existing studies have mainly focused on the analysis of the influence of short-circuit current on the stress distribution characteristics of windings. Wang Xue and others from North China Electric Power University studied the cumulative deformation characteristics of windings under multiple short-circuit currents. The study first considered the nonlinear elastic characteristics of the pads at different temperatures, and then calculated the stress and displacement distribution characteristics of the windings under the action of short-circuit currents through the electromagnetic-structural coupling finite element method. The research results show that with the increase of temperature under multiple short-circuit currents, the stress and plastic deformation of the transformer windings increase. Jawad Faiz and others from the University of Tehran in Iran obtained the electromagnetic force distribution characteristics of various parts of the winding under the action of short-circuit current based on the simulation of the two-dimensional finite element model of the transformer. The results show that the local axial force at the upper and lower ends of the transformer winding under the action of short-circuit current is much greater than the axial force in the middle part of the winding. The invention patent "Method for Calculating Short-Circuit Stress of Transformer Winding Transposition Structure" constructs a calculation model for the power frequency current short-circuit stress distribution of the transformer winding transposition structure by measuring the dimensional parameters of the transformer winding transposition structure. Based on the calculation results of the short-circuit electromagnetic force of the conductors in the transformer winding transposition structure, the spatial distribution of the axial, radial and total short-circuit stress of the conductors in the transformer winding transposition structure is obtained.

[0004] However, since harmonic current contains power frequency and multiple frequency current components, which are significantly different from power frequency short-circuit current, the existing research methods are not applicable to analyzing the stress distribution characteristics of windings under the action of harmonic current.

[0005] In summary, how to determine the winding stress under the action of different harmonic currents is a problem that needs to be solved urgently. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a method, device, equipment and medium for determining winding stress of a transformer winding, which can determine the winding stress under the action of different harmonic currents. The specific scheme is as follows:

[0007] In a first aspect, the present application discloses a method for determining winding stress of a transformer winding, comprising:

[0008] Determine the harmonic current components at each frequency of the harmonic current corresponding to the target transformer of the target material and the target type;

[0009] Determine a current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency, and determine a pre-calculated electromagnetic force associated with the current Young's modulus and corresponding to the harmonic current of each frequency; wherein the temperatures corresponding to different harmonic current components under the harmonic currents of different frequencies are the same or different; and the Young's modulus at different temperatures is different;

[0010] Calculating the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus, and calculating the sum of all the single winding mechanical stresses to obtain the total winding mechanical stress;

[0011] Calculating the single electromagnetic stress corresponding to the harmonic current of each frequency based on the electromagnetic force, and obtaining the total electromagnetic stress based on calculating the sum of all the single electromagnetic stresses;

[0012] The sum of the total winding mechanical stress and the total electromagnetic stress is calculated to obtain the winding stress of the transformer winding.

[0013] The calculating of the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus includes:

[0014] The single winding mechanical stress corresponding to the harmonic current of each frequency is obtained by calculating the product of the current Young's modulus, the linear expansion coefficient corresponding to the harmonic current component under the harmonic current of each frequency, and the temperature change value.

[0015] Before determining the pre-calculated electromagnetic force related to the current Young's modulus and corresponding to the harmonic current of each frequency, the method further includes:

[0016] Constructing a correlation model corresponding to the target transformer that represents the relationship between temperature and Young's modulus;

[0017] A dynamic response vibration model related to Young's modulus and electromagnetic force based on the transformer winding is constructed, and the dynamic response vibration model is coupled with the correlation model to calculate the electromagnetic force related to Young's modulus and corresponding to the harmonic current of each frequency.

[0018] The step of constructing a correlation model corresponding to the target transformer and representing the relationship between temperature and Young's modulus includes:

[0019] Determine temperatures corresponding to different harmonic current components at harmonic currents of different frequencies corresponding to the target transformer;

[0020] The Young's modulus corresponding to the partial temperature is measured, and a correlation model representing the relationship between temperature and Young's modulus is fitted based on the partial temperature and the style modulus corresponding to the partial temperature, including a temperature sensitivity coefficient; wherein the temperature sensitivity coefficient represents the sensitivity coefficient of Young's modulus to temperature changes; and is the same as or different from the temperature sensitivity coefficients corresponding to different harmonic current components under harmonic currents of different frequencies.

[0021] Wherein, determining the temperature corresponding to different harmonic current components of the target transformer under the harmonic currents of different frequencies includes:

[0022] Calculate the current density corresponding to different harmonic current components under the harmonic current of different frequencies;

[0023] Calculating the winding loss corresponding to the transformer winding according to the current density; the winding loss corresponding to different harmonic current components under harmonic currents of different frequencies is different;

[0024] The temperature of the target transformer corresponding to different harmonic current components under the harmonic currents of different frequencies is determined based on the winding loss.

[0025] The calculation of the current density corresponding to different harmonic current components under the harmonic currents of different frequencies includes:

[0026] Constructing a harmonic current coupling circuit model including a harmonic current model and a voltage balance model, and determining current values ​​corresponding to different harmonic current components under harmonic currents of different frequencies based on the harmonic current coupling circuit model;

[0027] An electromagnetic field model is constructed, and current densities corresponding to different harmonic current components under harmonic currents of different frequencies are calculated based on the current value and the electromagnetic field model.

[0028] In a second aspect, the present application discloses a device for determining winding stress of a transformer winding, comprising:

[0029] A harmonic current component determination module, used to determine the harmonic current component of the harmonic current at each frequency corresponding to the target transformer of the target material and the target type;

[0030] A Young's modulus determination module, used to determine a current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency; wherein the temperatures corresponding to different harmonic current components under the harmonic current of different frequencies are the same or different; and the Young's modulus at different temperatures is different;

[0031] an electromagnetic force determination module, for determining a pre-calculated electromagnetic force associated with the current Young's modulus and corresponding to the harmonic current of each frequency;

[0032] A mechanical stress calculation module, used for calculating the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus, and calculating the sum of all the single winding mechanical stresses to obtain the total winding mechanical stress;

[0033] An electromagnetic stress calculation module, used for calculating the single electromagnetic stress corresponding to the harmonic current of each frequency based on the electromagnetic force, and obtaining the total electromagnetic stress based on the sum of all the single electromagnetic stresses;

[0034] The winding stress calculation module is used to calculate the sum of the total winding mechanical stress and the total electromagnetic stress to obtain the winding stress of the transformer winding.

[0035] Among them, the mechanical stress calculation module is specifically used to calculate the product of the current Young's modulus and the linear expansion coefficient corresponding to the harmonic current component under the harmonic current of each frequency and the temperature change value to obtain the single winding mechanical stress corresponding to the harmonic current of each frequency.

[0036] In a third aspect, the present application discloses an electronic device, comprising:

[0037] Memory, used to store computer programs;

[0038] A processor is used to execute the computer program to implement the winding stress determination method of the transformer winding disclosed above.

[0039] In a fourth aspect, the present application discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the aforementioned method for determining winding stress of a transformer winding is implemented.

[0040] It can be seen that the harmonic current components under the harmonic current of each frequency corresponding to the target transformer of the target material and the target type are determined; the current Young's modulus corresponding to the harmonic current components under the harmonic current of each frequency is determined, and the electromagnetic force related to the current Young's modulus and corresponding to the harmonic current of each frequency, which is pre-calculated, is determined; wherein the temperatures corresponding to different harmonic current components under the harmonic currents of different frequencies are the same or different; the Young's modulus at different temperatures is different; the single winding mechanical stress corresponding to the harmonic current of each frequency is calculated based on the current Young's modulus, and the total winding mechanical stress is obtained by calculating the sum of all the single winding mechanical stresses; the single electromagnetic stress corresponding to the harmonic current of each frequency is calculated based on the electromagnetic force, and the total electromagnetic stress is obtained based on the calculation of the sum of all the single electromagnetic stresses; the winding stress of the transformer winding is obtained by calculating the sum of the total winding mechanical stress and the total electromagnetic stress. It can be seen that, first, the electromagnetic stress caused by the electromagnetic force generated by harmonic currents of different frequencies on the winding is taken into account when calculating the winding stress in the present application, thereby improving the calculation of the winding stress when harmonic currents exist; second, the present application determines the current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency, and the calculation of the winding mechanical stress and the winding electromagnetic stress both utilize the current Young's modulus. Therefore, the harmonic current will cause temperature changes, and the Young's modulus will be different at different temperatures. Therefore, the present application takes into account the impact of temperature changes on the winding stress, thereby improving the accuracy of the winding stress calculation; in summary, the present application can determine the winding stress under different harmonic currents. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0042] Figure 1 A flow chart of a method for determining winding stress of a transformer winding disclosed in the present application;

[0043] Figure 2 A flowchart of a method for determining winding stress of a specific transformer winding disclosed in the present application;

[0044] Figure 3 A schematic diagram of a winding stress determination process of a transformer winding disclosed in the present application;

[0045] Figure 4 A schematic diagram of a transformer winding circuit model disclosed in this application;

[0046] Figure 5 A schematic diagram of a longitudinal leakage magnetic flux density disclosed in the present application varying with the height of the main air channel;

[0047] Figure 6 A schematic diagram of a transverse leakage magnetic flux density according to the change of the main air channel height disclosed in the present application;

[0048] Figure 7 A schematic diagram of temperature distribution disclosed in this application;

[0049] Figure 8 A schematic diagram of the variation of Poisson's ratio and Young's modulus with temperature disclosed in the present application;

[0050] Fig. 9 A schematic diagram comparing transformer conditions with those with harmonic temperature rise ignored and those with harmonic temperature rise considered disclosed in the present application;

[0051] Fig.10 A schematic diagram of the structure of a device for determining winding stress of a transformer winding disclosed in the present application;

[0052] Fig.11 This is a structural diagram of an electronic device disclosed in this application. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Since harmonic current contains power frequency and multiple frequency current components, it is significantly different from power frequency short-circuit current. Existing research methods are not suitable for analyzing the stress distribution characteristics of windings under the action of harmonic current.

[0055] To this end, an embodiment of the present application proposes a winding stress determination scheme for a transformer winding, which can determine the winding stress under the action of different harmonic currents.

[0056] The present application discloses a method for determining winding stress of a transformer winding. Figure 1 As shown, the method includes:

[0057] Step S11: determining the harmonic current components of the harmonic current at each frequency corresponding to the target transformer of the target material and the target type.

[0058] In this embodiment, the corresponding currents of target transformers of different target materials and target types may be different, so the material and type need to be considered when calculating the stress.

[0059] Step S12: Determine the current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency, and determine the pre-calculated electromagnetic force related to the current Young's modulus and corresponding to the harmonic current of each frequency; wherein the temperatures corresponding to different harmonic current components under harmonic currents of different frequencies are the same or different; and the Young's modulus at different temperatures is different.

[0060] In this embodiment, since the temperatures corresponding to different harmonic current components under harmonic currents of different frequencies are the same or different, and the Young's modulus at different temperatures is different, it is necessary to determine the current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency, specifically based on the correspondence between the temperature obtained in advance based on the target transformer and the different harmonic current components under harmonic currents of different frequencies, as well as the relationship between temperature and Young's modulus.

[0061] Step S13: calculating the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus, and calculating the sum of all the single winding mechanical stresses to obtain the total winding mechanical stress.

[0062] In this embodiment, the calculation of the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus includes: calculating the product of the current Young's modulus and the linear expansion coefficient and temperature change value corresponding to the harmonic current component under the harmonic current of each frequency to obtain the single winding mechanical stress corresponding to the harmonic current of each frequency.

[0063] It should be pointed out that the formula for calculating the mechanical stress of a single winding is as follows:

[0064] ;

[0065] in, It represents the linear expansion coefficient under the kth harmonic (related to the material), without unit; Indicates the temperature change value under the kth harmonic ; Indicates the current Young's modulus, in Pa; Indicates the mechanical stress of a single winding, in Pa; It represents the mechanical stress of a single winding of the kth harmonic, in Pa.

[0066] The total winding mechanical stress calculation formula is as follows: .

[0067] Step S14: calculating the single electromagnetic stress corresponding to the harmonic current of each frequency based on the electromagnetic force, and obtaining the total electromagnetic stress based on calculating the sum of all the single electromagnetic stresses.

[0068] In this embodiment, the single electromagnetic stress calculation formula is as follows:

[0069] ;

[0070] in, is the single electromagnetic stress, which is the single electromagnetic stress when the kth harmonic current is present, and the unit is Pa; is the transformer conductor cross-sectional area, in units of ; is the electromagnetic force when the kth harmonic current is generated, and the unit is N.

[0071] The formula for the total electromagnetic stress is as follows:

[0072] ;

[0073] in, is the total electromagnetic stress.

[0074] Step S15: Calculate the sum of the total winding mechanical stress and the total electromagnetic stress to obtain the winding stress of the transformer winding.

[0075] The calculation formula for winding stress is as follows:

[0076] ;

[0077] in, Represents the winding stress of the transformer winding.

[0078] In summary, the present application firstly considers the influence of the temperature rise effect caused by harmonic current on the Young's modulus of the winding copper material, and then calculates the influence degree of the temperature rise effect of harmonic current on the mechanical stress of the winding; secondly, considers the influence of the nonlinear electromagnetic force generated by currents of different frequencies on the electromagnetic stress of the winding, and of course also considers the influence of the temperature rise effect on the electromagnetic force (Young's modulus), which is conducive to improving the accuracy of stress determination.

[0079] It can be seen that the present application determines the harmonic current components under the harmonic current of each frequency corresponding to the target transformer of the target material and the target type; determines the current Young's modulus corresponding to the harmonic current components under the harmonic current of each frequency, and determines the pre-calculated electromagnetic force related to the current Young's modulus and corresponding to the harmonic current of each frequency; wherein the temperatures corresponding to different harmonic current components under the harmonic currents of different frequencies are the same or different; the Young's modulus at different temperatures is different; based on the current Young's modulus, the single winding mechanical stress corresponding to the harmonic current of each frequency is calculated, and the sum of all the single winding mechanical stresses is calculated to obtain the total winding mechanical stress; based on the electromagnetic force, the single electromagnetic stress corresponding to the harmonic current of each frequency is calculated, and the total electromagnetic stress is obtained based on the calculation of the sum of all the single electromagnetic stresses; the sum of the total winding mechanical stress and the total electromagnetic stress is calculated to obtain the winding stress of the transformer winding. It can be seen that, first, the electromagnetic stress caused by the electromagnetic force generated by harmonic currents of different frequencies on the winding is taken into account when calculating the winding stress in the present application, thereby improving the calculation of the winding stress when harmonic currents exist; second, the present application determines the current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency, and the calculation of the winding mechanical stress and the winding electromagnetic stress both utilize the current Young's modulus. Therefore, the harmonic current will cause temperature changes, and the Young's modulus will be different at different temperatures. Therefore, the present application takes into account the impact of temperature changes on the winding stress, thereby improving the accuracy of the winding stress calculation; in summary, the present application can determine the winding stress under different harmonic currents.

[0080] The embodiment of the present application discloses a specific method for determining the winding stress of a transformer winding. Compared with the previous embodiment, this embodiment further illustrates and optimizes the technical solution. Figure 2 As shown, specifically including:

[0081] Step S21: constructing a correlation model corresponding to the target transformer that represents the relationship between temperature and Young's modulus.

[0082] In this embodiment, building an association model requires determining temperature and Young's modulus; the construction of the association model representing the relationship between temperature and Young's modulus corresponding to the target transformer includes: determining the temperature corresponding to different harmonic current components under harmonic currents of different frequencies corresponding to the target transformer; measuring the Young's modulus corresponding to some temperatures, and fitting the association model representing the relationship between temperature and Young's modulus including a temperature sensitivity coefficient based on the partial temperatures and the style modulus corresponding to the partial temperatures; wherein the temperature sensitivity coefficient represents the sensitivity coefficient of Young's modulus to temperature changes; and is the same as or different from the temperature sensitivity coefficient corresponding to different harmonic current components under harmonic currents of different frequencies.

[0083] It is important to point out that the association model is as follows:

[0084]

[0085] in, is the Young's modulus at temperature T, in Pa; is the reference temperature Young's modulus under , in Pa; It is the sensitivity coefficient of Young's modulus to temperature change and has no unit.

[0086] In this embodiment, determining the temperature corresponding to the target transformer under different harmonic current components of harmonic currents of different frequencies includes: calculating the current density corresponding to the different harmonic current components under the harmonic currents of different frequencies; calculating the winding loss corresponding to the transformer winding according to the current density; the winding losses corresponding to the different harmonic current components under the harmonic currents of different frequencies are different; and determining the temperature corresponding to the target transformer under different harmonic current components of harmonic currents of different frequencies based on the winding losses.

[0087] It should be noted that the loss may include network-measured winding loss and valve-side winding loss.

[0088] It should be pointed out that the winding losses corresponding to different harmonic current components under harmonic currents of different frequencies are calculated using the following formula:

[0089] ;

[0090] in, is the winding loss, in W; is the volume in units of ; t is time, unit is s; A sine cycle , unit is s; is the winding loss density, in units of ; Represents the current density of DC, in units of ; etc. are respectively expressed as the winding current density under different harmonic currents, and the unit is , n represents different harmonic currents.

[0091] It should be pointed out that the winding loss is substituted into the temperature calculation model (heat transfer equation and Navier-Stokes equation) to obtain the temperature distribution. The heat transfer equation is:

[0092] ;

[0093] The Navier-Stokes equation is given by:

[0094] ;

[0095] Finally, the temperature distribution can be obtained.

[0096] in, is the specific heat capacity, in J / (kg∙K); is the flow rate, in m / s, with a subscript Represents direction; is the external force on the fluid element, and the subscript Represents direction, the unit is N; is the pressure, the unit is Pa; is the dynamic viscosity, in N∙s / m2; is the density in Se is the ratio of the inertial force to the viscous force caused by the secondary flow, dimensionless, is the total winding loss in W.

[0097] In this embodiment, the calculation of current density corresponding to different harmonic current components under harmonic currents of different frequencies includes: constructing a harmonic current coupling circuit model including a harmonic current model and a voltage balance model, and determining current values ​​corresponding to different harmonic current components under harmonic currents of different frequencies based on the harmonic current coupling circuit model; constructing an electromagnetic field model, and calculating current density corresponding to different harmonic current components under harmonic currents of different frequencies based on the current value and the electromagnetic field model.

[0098] It should be pointed out that the harmonic current model is as follows:

[0099] ;

[0100] The voltage balance model is shown below:

[0101] ;

[0102] Among them, U(t) is the instantaneous value of the power supply voltage, the unit is V; i is the coil excitation current, the unit is A; R is the resistance matrix of the circuit, no unit; is the rated current of the winding, in A; is the circuit dynamic inductance matrix, unitless; is the potential generated by the harmonic current, in V; is the harmonic current content, no unit; n is the harmonic current number, no unit; t is the time, unit is s; It is the phase of harmonic current and has no units.

[0103] The current distribution data output by the above harmonic current coupling circuit model As the input condition of electromagnetic field simulation. The finite element method is used to calculate the magnetic field of the converter transformer under the action of harmonic current, the energy balance finite element method is used to calculate the magnetic vector potential A, and the vector magnetic potential A is used to solve the boundary value problem of the transformer nonlinear eddy current field. On this basis, the current density Jc of the winding and the magnetic induction intensity B at each point are further obtained.

[0104] The electromagnetic field model is shown below:

[0105] ;

[0106] in, is the vector magnetic potential, unit is Wb / m; is the magnetic induction intensity, the unit is T; is the winding current density, in units of ; is the conductivity, the unit is S / m; is the magnetic permeability, and its unit is H / m.

[0107] Step S22: construct a dynamic response vibration model related to Young's modulus and electromagnetic force based on the transformer winding, and couple the dynamic response vibration model with the association model to calculate the electromagnetic force related to Young's modulus and corresponding to the harmonic current of each frequency.

[0108] In this embodiment, the dynamic response vibration model is as follows:

[0109] ;

[0110] Among them, M is the winding mass matrix, without unit; C is the damping coefficient matrix, without unit; K(T) is the stiffness coefficient matrix considering the temperature effect, without unit; is the cross-sectional area of ​​the winding, in units of ; x is the winding displacement vector, unitless; f and G are the electromagnetic force and gravity of the converter transformer winding under the action of harmonics, unit N; is the current excitation amplitude The function represents the electromagnetic force caused by the current, with the unit of N; E(T) is the Young's modulus at temperature T, with the unit of Pa; L is the conductor length, with the unit of m.

[0111] It can be seen that the present application constructs an association model corresponding to the target transformer that represents the relationship between temperature and Young's modulus; constructs a dynamic response vibration model related to Young's modulus and electromagnetic force based on the transformer winding, and couples the dynamic response vibration model with the association model to calculate the electromagnetic force related to Young's modulus and corresponding to the harmonic current of each frequency. It can be seen that the present application associates electromagnetic force with Young's modulus for subsequent calculation of stress, and fully considers the influence of temperature on stress.

[0112] See also Figure 3 As shown, it is a schematic diagram of the winding stress determination process of a transformer winding; in the figure, a new model for calculating the vibration stress of the transformer winding considering the harmonic current temperature rise effect is first proposed, and then the harmonic current coupling circuit model is used to simulate the electromagnetic parameters of the transformer winding, and then the electromagnetic-heat flow coupling model is used to simulate the harmonic current temperature rise effect of the transformer winding, and finally the stress distribution characteristics of the transformer winding are calculated by coupling the harmonic current temperature rise effect; specifically, in step one, the mechanical stress and electromagnetic stress under the condition of harmonics and temperature changes caused by harmonics are calculated; in step two, the current is calculated by the harmonic current coupling circuit model, and the electromagnetic induction intensity is calculated according to the current and electromagnetic field model, that is, the electromagnetic density is calculated; in step three, the loss is calculated by the current density, and the temperature distribution is calculated based on the loss according to the heat transfer equation and the Navier-Tokes equation; in step four, the correlation between temperature and Young's modulus is constructed, and the stress distribution under the harmonic current and its temperature rise effect is obtained based on the winding dynamic response vibration equation.

[0113] Taking ZZDFPZ-405000 / 500-400 UHV converter transformer as an example, a detailed implementation method and specific operation process are given.

[0114] 1) Construct a harmonic current coupling circuit model to obtain the key electromagnetic parameters of the winding

[0115] Based on the geometric structure and material parameters of ZZDFPZ-405000 / 500-400 UHV converter transformer, a converter transformer winding circuit model with fundamental wave superimposed harmonic current is constructed. Figure 4 As shown in the figure, it is a schematic diagram of a transformer winding circuit model. Figure 4 The following contents are disclosed in the specification. First, there are voltage regulating windings, grid-side windings and valve-side windings in the transformer, and the current formulas corresponding to 1 and 2 in the transformer are as follows:

[0116] ;

[0117] ;

[0118] ;

[0119] ;

[0120] in, , represents the harmonic current source, , represents a fundamental sinusoidal current source, Indicates the content of harmonic current, It refers to the current phase angle, the unit is rad, and A is the current unit ampere.

[0121] The transient value of the coil current is solved by the circuit differential equation. The transient differential equation of the converter transformer winding circuit system is as follows:

[0122] ;

[0123] Among them, U(t) is the instantaneous value of the power supply voltage, the unit is V; i is the coil excitation current, the unit is A; R is the resistance matrix of the circuit, no unit; is the rated current of the winding, in A; is the circuit dynamic inductance matrix, unitless; is the harmonic current content, no unit; k is the harmonic current order, no unit; t is the time, unit is s; Phase, unitless.

[0124] The coil current distribution data obtained As the input condition of electromagnetic field simulation, the above electromagnetic field model is substituted as shown in the formula to calculate the distribution of magnetic induction intensity of the converter transformer. The distribution law of winding magnetic flux density under different harmonic currents is as follows: Figure 5 and Figure 6 As shown, Figure 5 It is a schematic diagram of the change of longitudinal leakage flux density with the height of the main air channel. Figure 6 Schematic diagram of the change of transverse leakage flux density with the height of the main air channel.

[0125] 2) Obtaining winding temperature distribution based on electromagnetic-thermal flow field

[0126] Based on the above finite element simulation solution, the magnetic flux density distribution and current density distribution of the UHV converter transformer can be obtained, and the winding loss can be further obtained by the analytical method. The calculated magnetic flux density distribution value is substituted into the above loss calculation model to obtain the grid-side winding and valve-side winding loss values ​​under harmonic currents of different frequencies. This paper simulates and calculates the winding loss distribution under the influence of the superposition of harmonic currents and fundamental currents with frequencies of 250Hz, 350Hz, 550Hz, and contents of 0%-20% at 250Hz, 350Hz, 550Hz, and 650Hz, respectively. This patent takes several typical harmonic currents as examples to carry out theoretical analysis, and the winding loss calculation results are shown in Table 1.

[0127] Table 1

[0128] Serial number Harmonic current content Grid side winding loss (W) Valve side winding loss (W) 1 0% 229386 271691 2 5%650Hz 252235 284157 3 10%650Hz 318638 321528 4 15%650Hz 429311 383813 5 20%650Hz 584252 471012 6 20%550Hz 485751 418920 7 20%350Hz 334086 334454 8 20%250Hz 282410 303964

[0129] Taking the loss density of the grid-side winding and valve-side winding obtained by electromagnetic field calculation as the heat source excitation for the thermal-flow field simulation calculation, this patent constructs a two-dimensional flow field model of the converter transformer with fine modeling. Based on the main control equations in the thermal flow field calculation, the heat transfer equation and the Navier-Stokes equation, the temperature distribution of the winding under the action of different harmonic currents is obtained. The winding temperature distribution characteristics under the influence of the superposition of harmonic currents and fundamental currents with frequencies of 250Hz, 350Hz, 550Hz, and contents of 0%, 5%, 10%, 15%, and 20% are simulated and analyzed. Taking the harmonic current frequencies of 250Hz and 650Hz as examples, this paper analyzes the distribution of the hot spot temperature of the grid-side winding and the valve-side winding under the action of different harmonic current contents, such as Figure 7 As shown, this is a schematic diagram of temperature distribution.

[0130] 3) Vibration stress calculation based on electromagnetic-thermal-solid force coupling model related to temperature and Young's modulus

[0131] Firstly, based on the material parameters of ZZDFPZ-405000 / 500-400 UHV converter transformer, the relationship between the Poisson's ratio and Young's modulus of the semi-hard copper material of the winding and temperature is obtained: nu(T), E(T) Figure 8 shown.

[0132] Then, the finite element method is used to couple the winding temperature distribution value obtained by the heat flow model to the solid force field model, and the magnetic field strength value obtained by the coupling circuit model is further used to obtain the electromagnetic stress value caused by the harmonic current. It is used as an excitation source to bring it into the vibration equation of the winding to obtain the force distribution of the total stress of the winding under the influence of different harmonic current components. Finally, the stress distribution of the converter transformer winding under the condition of ignoring the harmonic temperature rise is compared with the situation when the temperature rise effect caused by the harmonic current is considered. The distribution comparison cloud diagram is shown as follows: Fig. 9As shown in the figure, it is a schematic diagram comparing transformer conditions with ignoring harmonic temperature rise and considering harmonic temperature rise. After considering the harmonic current temperature rise, the distribution of the stress value of the winding changes. First, the overall stress of the winding is transferred to the middle of the winding, and secondly, the stress concentration point of the single-pie winding is also transferred to the middle of the single-pie winding. In addition, the simulation also calculates the change of the maximum stress value of the grid-side winding and the valve-side winding within a vibration cycle. Since the position of the maximum stress value changes within a cycle, the corresponding temperature field will also change. Therefore, the temperature rise effect caused by the harmonic current has different effects on the maximum stress value, increasing or weakening. Taking the most significant point of the stress effect as an example, a quantitative analysis is carried out. The harmonic temperature rise increases the maximum stress value of the grid-side winding by 40,000,000 N / m², an increase of 7.89%; the maximum stress value of the valve-side winding increases by 750,000 N / m², an increase of 20.05%. The results show that the temperature rise caused by the harmonic current has a significant impact on the winding stress, and also verify the scientificity and effectiveness of this simulation method.

[0133] In summary, this application proposes a new model for calculating the vibration stress of transformer windings taking into account the temperature rise effect of harmonic current, and then uses a harmonic current coupling circuit model to simulate and obtain the electromagnetic parameters of the transformer windings. Then, an electromagnetic-thermal flow coupling model is used to simulate and obtain the temperature rise effect of the harmonic current of the transformer windings. Finally, the harmonic current temperature rise effect is coupled to calculate the stress distribution characteristics of the transformer windings.

[0134] Correspondingly, the embodiment of the present application also discloses a device for determining winding stress of a transformer winding, see Fig.10 As shown, the device comprises:

[0135] A harmonic current component determination module 11 is used to determine the harmonic current component of each frequency of the harmonic current corresponding to the target transformer of the target material and the target type;

[0136] The Young's modulus determination module 12 is used to determine the current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency; wherein the temperatures corresponding to different harmonic current components under the harmonic current of different frequencies are the same or different; and the Young's modulus at different temperatures is different;

[0137] An electromagnetic force determination module 13, for determining a pre-calculated electromagnetic force associated with the current Young's modulus and corresponding to the harmonic current of each frequency;

[0138] A mechanical stress calculation module 14 is used to calculate the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus, and calculate the sum of all the single winding mechanical stresses to obtain the total winding mechanical stress;

[0139] An electromagnetic stress calculation module 15, configured to calculate the single electromagnetic stress corresponding to the harmonic current of each frequency based on the electromagnetic force, and obtain the total electromagnetic stress based on the sum of all the single electromagnetic stresses;

[0140] The winding stress calculation module 16 is used to calculate the sum of the total winding mechanical stress and the total electromagnetic stress to obtain the winding stress of the transformer winding.

[0141] The mechanical stress calculation module 14 is specifically used to calculate the product of the current Young's modulus and the linear expansion coefficient corresponding to the harmonic current component under the harmonic current of each frequency and the temperature change value to obtain the single winding mechanical stress corresponding to the harmonic current of each frequency.

[0142] Among them, the more specific working process of each of the above modules can refer to the corresponding content disclosed in the above embodiments, which will not be repeated here.

[0143] It can be seen that the harmonic current components under the harmonic current of each frequency corresponding to the target transformer of the target material and the target type are determined; the current Young's modulus corresponding to the harmonic current components under the harmonic current of each frequency is determined, and the electromagnetic force related to the current Young's modulus and corresponding to the harmonic current of each frequency, which is pre-calculated, is determined; wherein the temperatures corresponding to different harmonic current components under the harmonic currents of different frequencies are the same or different; the Young's modulus at different temperatures is different; the single winding mechanical stress corresponding to the harmonic current of each frequency is calculated based on the current Young's modulus, and the total winding mechanical stress is obtained by calculating the sum of all the single winding mechanical stresses; the single electromagnetic stress corresponding to the harmonic current of each frequency is calculated based on the electromagnetic force, and the total electromagnetic stress is obtained based on the calculation of the sum of all the single electromagnetic stresses; the winding stress of the transformer winding is obtained by calculating the sum of the total winding mechanical stress and the total electromagnetic stress. It can be seen that, first, the electromagnetic stress caused by the electromagnetic force generated by harmonic currents of different frequencies on the winding is taken into account when calculating the winding stress in the present application, thereby improving the calculation of the winding stress when harmonic currents exist; second, the present application determines the current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency, and the calculation of the winding mechanical stress and the winding electromagnetic stress both utilize the current Young's modulus. Therefore, the harmonic current will cause temperature changes, and the Young's modulus will be different at different temperatures. Therefore, the present application takes into account the impact of temperature changes on the winding stress, thereby improving the accuracy of the winding stress calculation; in summary, the present application can determine the winding stress under different harmonic currents.

[0144] Furthermore, an embodiment of the present application also provides an electronic device. Fig.11 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content in the diagram cannot be considered as any limitation on the scope of use of the present application.

[0145] Fig.11 The present invention provides a schematic diagram of the structure of an electronic device 20 provided in an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a display screen 23, an input / output interface 24, a communication interface 25, a power supply 26, and a communication bus 27. The memory 22 is used to store a computer program, and the computer program is loaded and executed by the processor 21 to implement the relevant steps in the method for determining the winding stress of the transformer winding disclosed in any of the aforementioned embodiments. In addition, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0146] In this embodiment, the power supply 26 is used to provide working voltage for each hardware device on the electronic device 20; the communication interface 25 can create a data transmission channel between the electronic device 20 and the external device, and the communication protocol it follows is any communication protocol that can be applied to the technical solution of the present application, and is not specifically limited here; the input and output interface 24 is used to obtain external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs and is not specifically limited here.

[0147] In addition, the memory 22, as a carrier for storing resources, may be a read-only memory, a random access memory, a disk or an optical disk, etc., and the resources stored thereon may include a computer program 221, and the storage method may be temporary storage or permanent storage. In addition to including a computer program that can be used to complete the method for determining the winding stress of a transformer winding executed by the electronic device 20 disclosed in any of the aforementioned embodiments, the computer program 221 may further include a computer program that can be used to complete other specific tasks.

[0148] Furthermore, an embodiment of the present application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the aforementioned method for determining winding stress of a transformer winding disclosed above is implemented.

[0149] The specific steps of the method can refer to the corresponding contents disclosed in the above embodiments, which will not be repeated here.

[0150] The various embodiments in this application are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0151] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0152] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0153] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0154] The above is a detailed introduction to the winding stress determination method, device, equipment, and storage medium of a transformer winding provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for determining winding stress of a transformer winding, characterized in that: include: Determine the harmonic current components at each frequency of the harmonic current corresponding to the target transformer of the target material and the target type; Determine a current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency, and determine a pre-calculated electromagnetic force associated with the current Young's modulus and corresponding to the harmonic current of each frequency; wherein the temperatures corresponding to different harmonic current components under the harmonic currents of different frequencies are the same or different; and the Young's modulus at different temperatures is different; Calculating the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus, and calculating the sum of all the single winding mechanical stresses to obtain the total winding mechanical stress; Calculating the single electromagnetic stress corresponding to the harmonic current of each frequency based on the electromagnetic force, and obtaining the total electromagnetic stress based on calculating the sum of all the single electromagnetic stresses; The sum of the total winding mechanical stress and the total electromagnetic stress is calculated to obtain the winding stress of the transformer winding.

2. The method for determining winding stress of a transformer winding according to claim 1, characterized in that: The calculating, based on the current Young's modulus, a single winding mechanical stress corresponding to the harmonic current of each frequency comprises: The single winding mechanical stress corresponding to the harmonic current of each frequency is obtained by calculating the product of the current Young's modulus, the linear expansion coefficient corresponding to the harmonic current component under the harmonic current of each frequency, and the temperature change value.

3. The method for determining winding stress of a transformer winding according to claim 1 or 2, characterized in that: Before determining the pre-calculated electromagnetic force related to the current Young's modulus and corresponding to the harmonic current of each frequency, the method further includes: Constructing a correlation model corresponding to the target transformer that represents the relationship between temperature and Young's modulus; A dynamic response vibration model related to Young's modulus and electromagnetic force based on the transformer winding is constructed, and the dynamic response vibration model is coupled with the correlation model to calculate the electromagnetic force related to Young's modulus and corresponding to the harmonic current of each frequency.

4. The method for determining winding stress of a transformer winding according to claim 3, characterized in that: The step of constructing a correlation model corresponding to the target transformer and representing the relationship between temperature and Young's modulus includes: Determine temperatures corresponding to different harmonic current components at harmonic currents of different frequencies corresponding to the target transformer; The Young's modulus corresponding to the partial temperature is measured, and a correlation model representing the relationship between temperature and Young's modulus is fitted based on the partial temperature and the style modulus corresponding to the partial temperature, including a temperature sensitivity coefficient; wherein the temperature sensitivity coefficient represents the sensitivity coefficient of Young's modulus to temperature changes; and is the same as or different from the temperature sensitivity coefficients corresponding to different harmonic current components under harmonic currents of different frequencies.

5. The method for determining winding stress of a transformer winding according to claim 4, characterized in that: The determining the temperature corresponding to the target transformer and corresponding to different harmonic current components under harmonic currents of different frequencies includes: Calculate the current density corresponding to different harmonic current components under the harmonic current of different frequencies; Calculating the winding loss corresponding to the transformer winding according to the current density; the winding loss corresponding to different harmonic current components under harmonic currents of different frequencies is different; The temperature of the target transformer corresponding to different harmonic current components under the harmonic currents of different frequencies is determined based on the winding loss.

6. The method for determining winding stress of a transformer winding according to claim 5, characterized in that: The calculating of current densities corresponding to different harmonic current components under harmonic currents of different frequencies includes: Constructing a harmonic current coupling circuit model including a harmonic current model and a voltage balance model, and determining current values ​​corresponding to different harmonic current components under harmonic currents of different frequencies based on the harmonic current coupling circuit model; An electromagnetic field model is constructed, and current densities corresponding to different harmonic current components under harmonic currents of different frequencies are calculated based on the current value and the electromagnetic field model.

7. A device for determining winding stress of a transformer winding, characterized in that: include: A harmonic current component determination module, used to determine the harmonic current component of the harmonic current at each frequency corresponding to the target transformer of the target material and the target type; A Young's modulus determination module, used to determine a current Young's modulus corresponding to the harmonic current component under the harmonic current of each frequency; wherein the temperatures corresponding to different harmonic current components under the harmonic current of different frequencies are the same or different; and the Young's modulus at different temperatures is different; an electromagnetic force determination module, for determining a pre-calculated electromagnetic force associated with the current Young's modulus and corresponding to the harmonic current of each frequency; A mechanical stress calculation module, used for calculating the single winding mechanical stress corresponding to the harmonic current of each frequency based on the current Young's modulus, and calculating the sum of all the single winding mechanical stresses to obtain the total winding mechanical stress; An electromagnetic stress calculation module, used for calculating the single electromagnetic stress corresponding to the harmonic current of each frequency based on the electromagnetic force, and obtaining the total electromagnetic stress based on the sum of all the single electromagnetic stresses; The winding stress calculation module is used to calculate the sum of the total winding mechanical stress and the total electromagnetic stress to obtain the winding stress of the transformer winding.

8. The device for determining winding stress of a transformer winding according to claim 7, characterized in that: The mechanical stress calculation module is specifically used to calculate the product of the current Young's modulus and the linear expansion coefficient corresponding to the harmonic current component under the harmonic current of each frequency and the temperature change value to obtain the single winding mechanical stress corresponding to the harmonic current of each frequency.

9. An electronic device, characterized in that: include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the method for determining the winding stress of a transformer winding according to any one of claims 1 to 6.

10. A computer-readable storage medium, characterized in that: Used to store a computer program; wherein, when the computer program is executed by a processor, the method for determining the winding stress of a transformer winding according to any one of claims 1 to 6 is implemented.

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