A method and device for obtaining short-circuit impedance of high-speed railway traction transformer

Abstract

The application relates to a method and system for obtaining short-circuit impedance of a high-speed rail traction transformer, which comprises the following steps: obtaining voltage and current fundamental signals of high-voltage side and low-voltage side windings of the high-speed rail traction transformer; constructing an elliptic equation according to the difference between the voltages of the high-voltage side and low-voltage side windings and the sum of the currents of the high-voltage side and low-voltage side windings; constructing a simplified equivalent circuit of the traction transformer under power frequency to obtain several constraint conditions of the elliptic equation coefficients; and calculating the reactance component and resistance component of the short-circuit impedance of the high-speed rail traction transformer based on the elliptic parameters of the elliptic equation and the obtained several constraint conditions. Compared with the prior art, the short-circuit impedance of the high-speed rail traction transformer is calculated by using the voltage and current signals of the high-voltage side and low-voltage side windings, the calculation precision is high, the calculation can be performed on line, and the method can be used for on-line state monitoring and fault diagnosis of the traction transformer.

Description

Technical Field

[0001] This invention relates to the field of transformer parameter identification technology, and in particular to a method and apparatus for obtaining the short-circuit impedance of a high-speed railway traction transformer. Background Technology

[0002] With the rapid development of high-power converter technology, high-speed railways generally adopt AC drive traction systems using an AC-DC-AC configuration to provide power. The AC drive traction system of high-speed railways mainly consists of a pantograph, traction transformer, traction rectifier, traction inverter, and traction motor. The traction transformer is one of the core components of the AC drive traction system, responsible for stepping down the 25kV high-voltage electricity from the traction grid to a low-voltage 1-2kV voltage that the subsequent converter can handle. Compared to ordinary power transformers operating statically, traction transformers operate under harsh conditions such as large temperature / humidity differences, strong vibrations, grid voltage fluctuations, high-order harmonics, frequent starts and stops, and frequent load changes. The cumulative effects of these long-term negative impacts can lead to latent faults in the transformer, which may develop into actual failures under certain conditions. Faults increase transformer heat generation, reduce insulation performance, and in severe cases, pose a fire hazard. Therefore, real-time online monitoring of the traction transformer's operating status is of great significance for the safe and reliable operation of high-speed railways. Due to strict limitations on external dimensions and axle load, traction transformers cannot be equipped with as many monitoring devices as ordinary power transformers, making online monitoring of traction transformers more difficult than that of ordinary power transformers.

[0003] Short-circuit impedance refers to the equivalent series impedance between the terminals of one winding in a transformer pair at rated frequency and reference temperature. It includes reactive and resistive components. The reactive component is affected by factors such as the relative positions and geometric dimensions of transformer components, mainly reflecting structural changes in components such as windings and core. The resistive component is affected by the state of the winding circuit, mainly reflecting short circuits between turns and layers, and open circuits. The degree of change in short-circuit impedance is a key indicator of transformer performance and has long been used in transformer condition assessment and fault diagnosis.

[0004] Traditional methods for measuring the short-circuit impedance of traction transformers require connection to a high-capacity, low-voltage adjustable power supply with adjustable amplitude before the transformer is put into operation. While this method offers high accuracy, it suffers from drawbacks such as being time-consuming, requiring power outages, and failing to detect faults promptly. Other methods for monitoring the condition and diagnosing faults in traction transformers, including chemical methods such as dissolved gas analysis and oil quality analysis, and electrical tests such as winding DC resistance testing and winding ratio testing, currently share the limitation of not being able to perform online monitoring. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a method and apparatus for obtaining the short-circuit impedance of a high-speed railway traction transformer.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for obtaining the short-circuit impedance of a high-speed railway traction transformer includes the following steps:

[0008] Acquire the fundamental voltage and current signals of the high-voltage and low-voltage windings of the high-speed railway traction transformer;

[0009] Construct an elliptic equation based on the voltage difference between the high-voltage and low-voltage windings of the transformer and the sum of the currents in the high-voltage and low-voltage windings;

[0010] A simplified equivalent circuit of the traction transformer at power frequency is constructed to obtain several constraint conditions for the coefficients of the elliptic equation.

[0011] Based on the elliptic parameters of the elliptic equation and several constraints, the reactance and resistance components of the short-circuit impedance of the high-speed railway traction transformer are calculated.

[0012] Furthermore, the process of extracting the fundamental voltage and current signals is as follows:

[0013] Extract the fundamental frequencies of the voltage and current signals from the high-voltage and low-voltage sides of the high-speed rail traction transformer for at least one cycle, and transfer the voltage and current from the low-voltage side to the high-voltage side to construct the expressions for the transformer's port voltage and current.

[0014] Furthermore, the processing expression for reducing the voltage and current on the low-voltage side to the high-voltage side includes:

[0015] U2=U 20 *K,I2=I 20 / K

[0016] In the formula, K is the transformer turns ratio; U 20 ,I 20 U1 and U2 are the amplitudes of the voltage and current at the low-voltage winding 1, respectively; U2 and I2 are the amplitudes of the voltage and current at the low-voltage winding 1 after being referred to the high-voltage side, respectively.

[0017] Furthermore, the expressions for the port voltage and current of the constructed transformer are as follows:

[0018] y=u1-u2=U1sin(ωt+α1)-U2sin(ωt+α2)

[0019] x=i1+i2=I1sin(ωt+β1)+I2sin(ωt+β2)

[0020] In the formula, y is the voltage difference between the high-voltage and low-voltage windings of the transformer, u1 is the voltage of the high-voltage winding of the transformer, u2 is the voltage of the low-voltage winding of the transformer, i1 is the current of the high-voltage winding of the transformer, i2 is the current of the low-voltage winding of the transformer, U1 and U2 are the amplitudes of the high-voltage winding branch terminal voltage and the low-voltage winding terminal voltage referred to the high-voltage side, respectively, I1 and I2 are the amplitudes of the high-voltage winding branch current and the low-voltage winding current referred to the high-voltage side, respectively, ω is the angular frequency of the traction grid; α1 and α2 are the initial phases of the high-voltage winding branch terminal voltage and the low-voltage winding terminal voltage, respectively, and β1 and β2 are the initial phases of the high-voltage winding branch current and the low-voltage winding current, respectively.

[0021] Furthermore, the expression for the constructed ellipse equation is:

[0022] Ax 2 +Bxy+Cy 2 +D=0

[0023] Where A, B, C, and D are the coefficients of the ellipse equation:

[0024]

[0025] C=1

[0026] D=-[U2sin(α2-k2)-U1sin(α1-k2)] 2 .

[0027] Furthermore, by neglecting the influence of the excitation current, a simplified equivalent circuit of the traction transformer at power frequency is constructed, yielding several constraint conditions for the coefficients of the elliptic equation, including:

[0028] k1 = 2I2, k2 = 0

[0029] U1cosα1=I2(R k +R L ),U1sinα1=I2(X k +X L )

[0030] U2cosα2=I2R L U²sinα²=I²X L

[0031] In the formula, R k X k These are the resistive and reactive components of the transformer's short-circuit impedance, R. L X L These are the resistive and reactive components of the load connected to the transformer, respectively.

[0032] Furthermore, the ellipse parameters of the ellipse equation include the ellipse inclination angle θ, the semi-major axis a, and the semi-minor axis b.

[0033] Based on the elliptic parameters of the elliptic equation and several constraints, the reactance component X of the short-circuit impedance of the high-speed rail traction transformer is obtained. k The calculation expression is:

[0034]

[0035] In the formula, X k This represents the reactance component of the short-circuit impedance.

[0036] Furthermore, the reactance component X of the short-circuit impedance k In the calculation expression, the magnitude of the current at the low-voltage winding 1 end after being referred to the high-voltage side, I2, is 0.5*(I1+I2).

[0037] Furthermore, the calculation process for the resistive component of the short-circuit impedance is as follows:

[0038] The resistive component R of the short-circuit impedance k The formula for calculating a quadratic equation in one variable is given. Solving it yields two solutions, but the one with a magnitude much larger than R is discarded. k The meaningless solution is given by the other solution, which is the resistive component R of the short-circuit impedance. k ;

[0039] The formula for calculating the quadratic equation in one variable is:

[0040]

[0041] Furthermore, the method also includes online condition monitoring and fault diagnosis of the high-speed railway traction transformer based on the reactance and resistance components of the short-circuit impedance obtained.

[0042] The present invention also provides a system for obtaining the short-circuit impedance of a high-speed railway traction transformer, including a memory and a processor. The memory stores a computer program, and the processor calls the computer program to execute the steps of the method described above.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) This invention is based on a simplified equivalent circuit of a transformer and uses the voltage and current signals of the high-voltage and low-voltage windings of the transformer to calculate the short-circuit impedance of the high-speed rail traction transformer. This method has high accuracy, can be calculated online, and can be used for online status monitoring and fault diagnosis of traction transformers.

[0045] (2) This invention uses the voltage and current signals of the high-voltage and low-voltage windings of the high-speed rail traction transformer to calculate the short-circuit impedance. No additional monitoring equipment is required, and online calculation can be achieved.

[0046] (3) The method of this invention can be used for online condition monitoring and fault diagnosis of high-speed railway traction transformers. Since short-circuit impedance has a clear physical meaning, its interpretability is stronger than traditional methods such as frequency response analysis. Attached Figure Description

[0047] Figure 1 This is a flowchart illustrating a method for obtaining the short-circuit impedance of a high-speed railway traction transformer provided in an embodiment of the present invention.

[0048] Figure 2 This is a schematic diagram of an axially split four-part transformer provided in an embodiment of the present invention;

[0049] Figure 3 This invention provides a simplified equivalent circuit for a high-speed rail traction transformer in an embodiment of the invention.

[0050] Figure 4 This invention provides a simulation calculation of the resistance component R of the short-circuit impedance at different times, as provided in this embodiment. k and reactance component X k The result image. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0053] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0054] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0055] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0056] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0057] Example 1

[0058] like Figure 1 As shown in the figure, this embodiment provides a method for obtaining the short-circuit impedance of a high-speed railway traction transformer, including the following steps:

[0059] Step 1: Obtain the fundamental voltage and current signals of the high-voltage and low-voltage windings of the high-speed rail traction transformer;

[0060] Step 2: Construct an elliptic equation based on the voltage difference between the high-voltage and low-voltage windings of the transformer and the sum of the currents in the high-voltage and low-voltage windings;

[0061] Step 3: Construct a simplified equivalent circuit of the traction transformer at power frequency to obtain several constraint conditions for the coefficients of the elliptic equation.

[0062] Step 4: Based on the elliptic parameters of the elliptic equation and the obtained constraints, calculate the reactance and resistance components of the short-circuit impedance of the high-speed rail traction transformer.

[0063] The following is a detailed description of each step.

[0064] Step 1:

[0065] High-speed rail traction transformers generally employ an axial n-split winding configuration, meaning the high-voltage winding has n branches and the low-voltage winding has n windings, with each high-voltage branch coupled to only one low-voltage winding. This invention describes the most common axial four-split transformer (n=4), such as... Figure 2 As shown, the same applies to other cases. This scheme uses the fundamental frequencies of the voltage and current signals from the high-voltage and low-voltage sides of the high-speed rail traction transformer to calculate the short-circuit impedance. Since there are a large number of power electronic switches in the traction power grid, the original voltage and current signals will contain a large number of harmonic components. Therefore, it is necessary to first filter them to retain only the fundamental components.

[0066] Select a high-voltage winding branch 1 and its coupled low-voltage winding 1 to be tested. Let i1 and u1 be the terminal current and terminal voltage of the high-voltage winding branch 1, and i2 and u2 be the terminal current and terminal voltage of the low-voltage winding 1 referred to the high-voltage side according to the turns ratio. Since traction transformers are all single-phase transformers, the method for referring the voltage and current on the low-voltage side to the high-voltage side is: U2 = U 20 *K,I2=I 20 / K. Where K is the transformer turns ratio; U 20 ,I 20 U1 and U2 are the amplitudes of the voltage and current at the low-voltage winding 1, respectively; U2 and I2 are the amplitudes of the voltage and current at the low-voltage winding 1 after being referred to the high-voltage side, respectively.

[0067] Ideally, the instantaneous values ​​of the transformer's port voltage and current can be represented by trigonometric functions:

[0068] y=Δu=u1-u2=U1sin(ωt+α1)-U2sin(ωt+α2)#(1)

[0069] x=∑i=i1+i2=I1sin(ωt+β1)+I2sin(ωt+β2)#(2)

[0070] Where ω is the angular frequency of the traction power grid; α1 and α2 are the initial phases of the high-voltage winding branch voltage and the low-voltage winding terminal voltage, respectively; β1 and β2 are the initial phases of the high-voltage winding branch current and the low-voltage winding current, respectively; U1 and U2 are the amplitudes of the high-voltage winding branch voltage and the low-voltage winding terminal voltage, respectively; and I1 and I2 are the amplitudes of the high-voltage winding branch current and the low-voltage winding current, respectively.

[0071] Step Two:

[0072] Since i1 and i2 have the same frequency, equation (2) can be transformed into:

[0073] x=k1sin(ωt+k2)#(3)

[0074] Where the coefficients k1 and k2 are respectively:

[0075]

[0076] From equation (3), we get:

[0077]

[0078] Substitute equation (5) into equation (1). And because... Therefore:

[0079]

[0080] Equation (6) can be rearranged as follows:

[0081]

[0082] Squaring both sides of equation (7) and rearranging, we get:

[0083]

[0084] Equation (8) can also be written in the following form:

[0085] Ax 2 +Bxy+Cy 2 +D=0#(9)

[0086] in:

[0087] #

[0088]

[0089] C=1, D=-[U2sin(α2-k2)-U1sin(α1-k2)] 2 #(10)

[0090] Step 3:

[0091] The excitation current measured under no-load conditions of a traction transformer is typically only about 0.5% of its rated current. According to relevant circuit knowledge, if the influence of the excitation current is ignored, the traction transformer can be used at power frequency. Figure 3 The simplified equivalent circuit representation is shown below. Where R... k X k These are the resistive and reactive components of the transformer's short-circuit impedance, R. L X L These are the resistive and reactive components of the load connected to the transformer, respectively.

[0092] from Figure 3 We can see that I1 = I2 and β1 = β2. Letting β1 = β2 = 0 and substituting into equation (4) gives:

[0093] k1 = 2I2, k2 = 0#(11)

[0094] also, Figure 3 The following relationship can also be obtained:

[0095] U1cos α1=I2(R k +R L ), U1sinα1=I2(X k +X L )

[0096] U2cosα2=I2R L U2sinα2=I2X L #(12)

[0097] Substituting equations (11) to (12) into equation (10) and rearranging, we get:

[0098]

[0099] Therefore, for equation (9), we have:

[0100]

[0101] According to relevant mathematical knowledge, when B 2 -4AC: When greater than 0, equation (9) represents a hyperbola; when equal to 0, equation (9) represents a parabola; when less than 0, equation (9) represents an ellipse. Since in equation (14) the numerator U2sin(α2-k2)-U1sin(α1-k2)=I2X k Since k≠0, and the denominator k₁ = 2I₂ ≠0, therefore B 2 -4AC<0. Equation (9) is an elliptic equation.

[0102] Based on relevant mathematical knowledge, the ellipse Ax 2 +Bxy+Cy 2 +D=0 satisfies the following formula:

[0103] 1. Formula for the inclination angle θ of an ellipse:

[0104]

[0105] 2. Formula for the semi-major axis 'a' of an ellipse:

[0106]

[0107] 3. Formula for the semi-minor axis b of an ellipse:

[0108]

[0109] Step Four:

[0110] Substituting equation (13) into equations (15) and (16), we get:

[0111]

[0112]

[0113] Multiplying equations (18) and (19) and simplifying, we get:

[0114]

[0115] Therefore, the reactance component X of the short-circuit impedance k The calculation formula is:

[0116]

[0117] In practice, there will be a slight difference between the amplitude of the high-voltage winding branch current and the amplitude of the low-voltage winding current referred to the high-voltage side. I2 in equation (21) can be replaced by 0.5*(I1+I2) to improve the accuracy of the calculation.

[0118] Substituting equation (13) into equation (15) and rearranging, we get:

[0119]

[0120] Due to the reactance component X of the short-circuit impedance k It has been calculated by equation (21). Therefore, the resistive component R of the short-circuit impedance k The formula for calculating it is a quadratic equation in one variable:

[0121]

[0122] The discriminant of equation (23) is:

[0123]

[0124] For high-speed rail traction transformers, in order to reduce short-circuit current and lower losses, X is incorporated into the design. k Typically several hundred ohms, which is R k The value is ten to several tens of times greater than the given value, at which point Δ must be greater than 0. Therefore, equation (23) has two solutions: one is the solution to the problem of finding R. k One is that the order of magnitude is much larger than R. k The meaningless solution is discarded.

[0125] This embodiment also provides a system for obtaining the short-circuit impedance of a high-speed railway traction transformer, including a memory and a processor. The memory stores a computer program, and the processor calls the computer program to execute the steps of the method for obtaining the short-circuit impedance of a high-speed railway traction transformer as described above.

[0126] The following is a simulation verification process for the transformer short-circuit impedance calculation method of the present invention:

[0127] A field-circuit coupling simulation model of the traction transformer and traction rectifier was established, simulating the actual working state of the traction transformer in high-speed rail. The traction transformer was modeled using a two-dimensional finite element method, and the traction rectifier using a circuit model. Simulation parameters are shown in Table 1. After obtaining the voltage and current signals on the high-voltage and low-voltage sides of the transformer through simulation, the elliptic equation was fitted using the least squares method. The resistance component of the transformer's short-circuit impedance calculated by simulation differs from the sum of the high-voltage winding branch resistance and the low-voltage winding resistance calculated according to the turns ratio on the high-voltage side by approximately 3%, a deviation that meets engineering requirements.

[0128] exist Figure 4 In the simulation, the transformer short-circuit impedance is pre-set to be calculated every 20 milliseconds. During the 300-millisecond period (0.9-1.2 seconds after simulation begins), X... k The deviation from the average value shall not exceed 0.05%. k The deviation from the average value is no more than 1.2%, and the fluctuation does not affect the condition monitoring and fault diagnosis of the traction transformer, indicating that the short-circuit impedance calculation method of the present invention can be used for online real-time calculation.

[0129] After adding an inductor or resistor in series with the low-voltage winding of the transformer, the short-circuit impedance of the transformer will change accordingly. As can be seen from Tables 2 and 3, the short-circuit impedance calculation method of the present invention can accurately reflect the changes before and after adding the inductor or resistor. Specifically, the error in calculating the added inductor is 0.69%, and the error in calculating the added resistance is 3.22%, indicating that the short-circuit impedance calculation method of the present invention has high accuracy.

[0130] Table 1 Simulation Parameters

[0131]

[0132] 1) Continuous calculation verification: R is calculated at different times. k and X k The result is as follows Figure 4 As shown.

[0133] 2) Accuracy verification:

[0134] 2.1. Connect a 0.1mH inductor in series in the low-voltage winding circuit, with the inductor positioned between the load and the low-voltage winding. The calculation results are shown in Table 2.

[0135] Table 2. Low-voltage winding circuit with series 0.1mH inductor before and after

[0136] parameter <![CDATA[R k / Oh]]> <![CDATA[X k / Oh]]> Calculated values ​​without series inductor 14.0935 422.1552 Calculated value after series inductance 14.2111 443.5384 Calculated value of 0.1mH inductance —— 21.3832 Actual value of 0.1mH inductance* —— 21.2372 error —— 0.69％

[0137] *Referred to the high-voltage side according to the transformer turns ratio

[0138] 2.2. A 0.005Ω resistor was connected in series in the low-voltage winding circuit, with the resistor positioned between the load and the low-voltage winding. The results are shown in Table 3.

[0139] Table 3 shows the series resistance of 0.005Ω before and after the low-voltage winding circuit.

[0140] parameter <![CDATA[R k / Oh]]> <![CDATA[X k / Oh]]> Calculated value without series resistor 14.0935 422.1552 Calculated value after series resistance 17.5823 421.5540 Calculated value of 0.005Ω resistance 3.4888 —— Actual value of 0.005Ω resistor* 3.3800 —— error 3.22％ ——

[0141] *Referred to the high-voltage side according to the transformer turns ratio

[0142] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for obtaining the short-circuit impedance of a high-speed railway traction transformer, characterized in that, Includes the following steps: Acquire the fundamental voltage and current signals of the high-voltage and low-voltage windings of the high-speed railway traction transformer; Construct an elliptic equation based on the voltage difference between the high-voltage and low-voltage windings of the transformer and the sum of the currents in the high-voltage and low-voltage windings; A simplified equivalent circuit of the traction transformer at power frequency is constructed to obtain several constraint conditions for the coefficients of the elliptic equation. Based on the elliptic parameters of the elliptic equation and several constraints, the reactance and resistance components of the short-circuit impedance of the high-speed rail traction transformer are calculated. The expression for the constructed ellipse equation is as follows: In the formula, y This is the voltage difference between the high-voltage and low-voltage windings of the transformer. , These are the amplitudes of the high-voltage winding branch terminal voltage and the low-voltage winding terminal voltage referred to the high-voltage side, respectively. , These are the initial phases of the high-voltage winding branch voltage and the low-voltage winding terminal voltage, respectively. and For coefficients, , , , These are the amplitudes of the high-voltage winding branch current and the low-voltage winding current referred to the high-voltage side, respectively. , These are the initial phases of the high-voltage winding branch current and the low-voltage winding current, respectively. By neglecting the influence of the excitation current, a simplified equivalent circuit of the traction transformer at power frequency is constructed, and several constraint conditions for the coefficients of the elliptic equation are obtained, including: In the formula, , These are the resistive and reactive components of the transformer's short-circuit impedance, respectively. , These are the resistive and reactive components of the load connected to the transformer, respectively. It is the amplitude of the low-voltage winding current after being referred to the high-voltage side.

2. The method for obtaining the short-circuit impedance of a high-speed railway traction transformer according to claim 1, characterized in that, The specific process of extracting the fundamental voltage and current signals is as follows: Extract the fundamental frequencies of the voltage and current signals from the high-voltage and low-voltage sides of the high-speed rail traction transformer for at least one cycle, and transfer the voltage and current from the low-voltage side to the high-voltage side to construct the expressions for the transformer's port voltage and current.

3. The method for obtaining the short-circuit impedance of a high-speed railway traction transformer according to claim 2, characterized in that, The expressions for the port voltage and current of the constructed transformer are as follows: In the formula, This refers to the voltage of the high-voltage winding of the transformer. This refers to the voltage of the low-voltage winding of the transformer. This refers to the current in the high-voltage winding of the transformer. This refers to the current in the low-voltage winding of the transformer. This is the angular frequency of the traction power grid.

4. The method for obtaining the short-circuit impedance of a high-speed railway traction transformer according to claim 1, characterized in that, The ellipse parameters in the ellipse equation include the ellipse inclination angle. ellipse semi-major axis and the semi-minor axis of the ellipse ; Based on the elliptic parameters derived from the elliptic equation and several constraints, the reactance component of the short-circuit impedance of the high-speed rail traction transformer is obtained. The calculation expression is: In the formula, This represents the reactance component of the short-circuit impedance.

5. The method for obtaining the short-circuit impedance of a high-speed railway traction transformer according to claim 4, characterized in that, The reactance component of the short-circuit impedance In the calculation expression, the amplitude of the current at terminal 1 of the low-voltage winding after being referred to the high-voltage side. The value is 0.5 ( ).

6. The method for obtaining the short-circuit impedance of a high-speed railway traction transformer according to claim 4, characterized in that, The calculation process for the resistive component of the short-circuit impedance is as follows: The resistive component of the short-circuit impedance The formula for calculating a quadratic equation in one variable yields two solutions; the one with a magnitude much larger than 1 is discarded. The meaningless solution is given by the other solution, which is the resistive component of the short-circuit impedance. ; The formula for calculating the quadratic equation in one variable is:

7. The method for obtaining the short-circuit impedance of a high-speed railway traction transformer according to claim 1, characterized in that, The method also includes online condition monitoring and fault diagnosis of the high-speed railway traction transformer based on the reactance and resistance components of the short-circuit impedance obtained.

8. A system for obtaining the short-circuit impedance of a high-speed railway traction transformer, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program, and the processor invokes the computer program to perform the steps of the method as described in any one of claims 1 to 7.

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