Method and device for extracting high-frequency parameters of converter transformer of null bus high-frequency resonance

Abstract

The invention provides a converter transformer high-frequency parameter extraction method and device for null bus high-frequency resonance, and relates to the field of flexible direct current transmission system converter station operation analysis, and the method comprises the steps: determining a corresponding frequency response characteristic according to the obtained network side voltage data of a converter transformer; constructing a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the network side port of the converter transformer and the frequency response characteristic; and determining corresponding converter transformer high-frequency parameters based on the converter transformer high-frequency model. According to the method, the theoretical frequency response data and the actually measured frequency response data of the converter transformer can be fitted based on the actually measured frequency response data of the converter transformer in engineering, and then the high-frequency model parameters of the converter transformer are obtained through inversion.

Description

Technical Field

[0001] The present application relates to the field of operation analysis of converter stations in flexible direct current transmission systems, and specifically to a method for extracting high-frequency model parameters of converter transformers for high-frequency resonance of empty busbars in flexible direct current converter stations. Background Art

[0002] In recent years, the green and low-carbon transformation of energy has become a new trend, and the grid connection of onshore and offshore wind farm clusters has become a major direction for the development of new energy at this stage. However, since the distribution of renewable energy and the main electricity consumption market are often inversely distributed, large-capacity and long-distance transmission has become the main bottleneck restricting the development of new energy. High-voltage direct current (HVDC) transmission based on modular multilevel converters (flexible direct current) has become an important technical means for large-scale new energy power transmission due to its advantages such as low harmonic content, flexible control, and no commutation failure. However, with the continuous advancement of flexible direct current converter transmission technology in engineering applications, the resulting high-frequency resonance problem has also begun to emerge.

[0003] As a key device in the flexible DC system, the existing high-frequency resonance analysis methods simply use leakage reactance for equivalent modeling, without considering the capacitance effect of the converter transformer in the high-frequency band. In fact, the high-frequency characteristics of the converter transformer have an important influence on the high-frequency resonance of the flexible DC system, especially the high-frequency resonance of the empty busbar of the flexible DC converter station. It is necessary to accurately model and extract the high-frequency resonance parameters of the converter transformer in order to scientifically and rationally study the high-frequency resonance problem of the empty busbar of the flexible DC converter station.

[0004] The high-frequency equivalent model parameters of traditional transformers are obtained through electromagnetic field analysis and calculation or experimental measurement. Electromagnetic field analysis and calculation require the structure, size, medium parameters and other data of the transformer to establish a detailed 3D finite element model. However, for transformers that have been put into operation, the above data is not only difficult to obtain, but also the numerical calculations involved are extremely complex. The experimental measurement operation is complicated and depends on the professional level of the technicians, which can easily lead to inaccurate parameters. For this reason, it is necessary to find a new method for extracting high-frequency model parameters of converter transformers. Summary of the invention

[0005] In response to the problems in the prior art, the present application provides a method and device for extracting high-frequency parameters of a converter transformer with empty bus high-frequency resonance, which can fit the theoretical frequency response data of the converter transformer with the measured frequency response data based on the frequency response data of the converter transformer measured in the project, and then inversely obtain the high-frequency model parameters of the converter transformer.

[0006] In order to solve the above technical problems, this application provides the following technical solutions:

[0007] In a first aspect, the present application provides a method for extracting high-frequency parameters of a converter transformer with empty bus high-frequency resonance, comprising:

[0008] Determine the corresponding frequency response characteristics according to the acquired grid-side voltage data of the converter transformer;

[0009] Constructing a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics;

[0010] The corresponding high-frequency parameters of the converter transformer are determined based on the high-frequency model of the converter transformer.

[0011] Further, the grid-side voltage data includes a response terminal voltage and an excitation terminal voltage; and determining the corresponding frequency response characteristics according to the acquired grid-side voltage data of the converter transformer includes:

[0012] Apply a variable frequency sinusoidal voltage excitation to the first terminal of the grid-side winding of the converter transformer, and connect the second terminal of the grid-side winding of the converter transformer to a matching resistor; wherein the two terminals of the valve-side winding of the converter transformer are suspended;

[0013] The ratio of the response terminal voltage to the excitation terminal voltage at different frequencies is calculated to determine the frequency response characteristics of the transformer.

[0014] Furthermore, the constructing of the converter transformer high-frequency model according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristic includes:

[0015] Determine the equivalent impedance according to the grid-side current of the converter transformer, the response terminal voltage and the excitation terminal voltage;

[0016] The converter transformer high frequency model is determined according to the corresponding relationship between the equivalent impedance and the frequency response characteristic.

[0017] Furthermore, determining the corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer includes:

[0018] Initialize the parameter set to be solved; wherein the parameter set is the optimal point obtained in each iteration;

[0019] Based on the preset objective function, the parameter set obtained by inversion using the improved Powell algorithm is used as the optimal point obtained in the current round of iterations and compared with the optimal point obtained in the previous round of iterations;

[0020] If the difference between the optimal point obtained in the current round of iteration and the optimal point obtained in the previous round of iteration meets the convergence condition or reaches the maximum number of iterations, the program is terminated; wherein the optimal point obtained in the current round of iteration is used as the high-frequency parameter of the converter transformer;

[0021] Otherwise, the parameter set is reinitialized, the search direction group is updated, and the optimal point of the objective function is recalculated.

[0022] Furthermore, the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar further includes:

[0023] Determining the calculated amplitude and calculated phase of the frequency response of the converter transformer by using the converter transformer high frequency model;

[0024] Based on a preset error rate calculation function, the calculated amplitude and calculated phase are compared with corresponding measured data to verify the accuracy of the high-frequency model of the converter transformer.

[0025] In a second aspect, the present application provides a high-frequency parameter extraction device for a converter transformer with empty bus high-frequency resonance, comprising:

[0026] A frequency characteristic determination unit, used to determine a corresponding frequency response characteristic according to the acquired grid-side voltage data of the converter transformer;

[0027] A high-frequency model building unit, used to build a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics;

[0028] A high-frequency parameter determination unit is used to determine the corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer.

[0029] Furthermore, the grid-side voltage data includes a response terminal voltage and an excitation terminal voltage; and the frequency characteristic determination unit includes:

[0030] A voltage excitation module, used for applying a frequency-variable sinusoidal voltage excitation to the first terminal of the grid-side winding of the converter transformer, and connecting the second terminal of the grid-side winding of the converter transformer to a matching resistor; wherein the two terminals of the valve-side winding of the converter transformer are suspended;

[0031] The frequency characteristic determination module is used to calculate the ratio of the response terminal voltage to the excitation terminal voltage at different frequencies to determine the frequency response characteristic of the transformer.

[0032] Furthermore, the high-frequency model building unit includes:

[0033] An equivalent impedance determination module, used to determine the equivalent impedance according to the grid-side current of the converter transformer, the response terminal voltage and the excitation terminal voltage;

[0034] A high-frequency model building module is used to determine the high-frequency model of the converter transformer according to the corresponding relationship between the equivalent impedance and the frequency response characteristic.

[0035] Furthermore, the high frequency parameter determination unit includes:

[0036] A parameter initialization module is used to initialize the parameter set to be solved; wherein the parameter set is the optimal point obtained in each iteration;

[0037] An iterative comparison module is used to compare the parameter set obtained by inversion using the improved Powell algorithm as the optimal point obtained in the current round of iterations with the optimal point obtained in the previous round of iterations based on a preset objective function;

[0038] A difference comparison module is used to terminate the program if the difference between the optimal point obtained in the current round of iteration and the optimal point obtained in the previous round of iteration meets the convergence condition or reaches the maximum number of iterations; wherein the optimal point obtained in the current round of iteration is used as the high-frequency parameter of the converter transformer;

[0039] The calculation module is adjusted to reinitialize the parameter set, update the search direction group, and recalculate the optimal point of the objective function.

[0040] Furthermore, the high-frequency parameter extraction device for the converter transformer with empty bus high-frequency resonance further includes:

[0041] An amplitude and phase module, used to determine the calculated amplitude and calculated phase of the frequency response of the converter transformer using the high-frequency model of the converter transformer;

[0042] The model verification module is used to compare the calculated amplitude and calculated phase with the corresponding measured data based on a preset error rate calculation function to verify the accuracy of the high-frequency model of the converter transformer.

[0043] In a third aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of a method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty bus are implemented.

[0044] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty bus.

[0045] In a fifth aspect, the present application provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty bus.

[0046] In response to the problems in the prior art, the method and device for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar provided in the present application can take into account the capacitance effect of the converter transformer in the high-frequency band, establish a high-frequency equivalent model of the converter transformer, and use the improved Powell algorithm to fit the theoretical frequency response data of the transformer with the measured frequency response data of the transformer, and inversely calculate and obtain the high-frequency model parameters of the converter transformer, thereby avoiding the problems of difficulty in establishing a finite element model for electromagnetic field analysis and calculation, complex calculations, complex experimental measurement operations, inaccurate parameters, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A flowchart of a method for extracting high-frequency model parameters of a converter transformer provided in an embodiment of the present application;

[0049] Figure 2 A schematic diagram of a low-frequency model of a converter transformer provided in an embodiment of the present application;

[0050] Figure 3 A schematic diagram of a high-frequency equivalent model of a converter transformer provided in an embodiment of the present application;

[0051] Figure 4 A schematic diagram of a high-frequency simplified model of a converter transformer ignoring the ground branch provided in an embodiment of the present application;

[0052] Figure 5 A schematic diagram of high-frequency impedance equivalents of a converter transformer provided in an embodiment of the present application;

[0053] Figure 6 A schematic diagram of a transformer frequency response characteristic detection circuit provided in an embodiment of the present application;

[0054] Figure 7 A schematic diagram of the parameter flow of the inversion calculation model of the improved Powell algorithm provided in the embodiment of the present application;

[0055] Figure 8a A schematic diagram of the comparison between the calculated and actual amplitudes within 10kHz provided in the embodiment of the present application;

[0056] Figure 8b A schematic diagram of the comparison between the calculated and actual phases within 10 kHz provided in an embodiment of the present application;

[0057] Figure 9a A schematic diagram of the calculated and actual amplitude error rate within 10kHz provided in an embodiment of the present application;

[0058] Figure 9b A schematic diagram of the calculated and actual phase error rate within 10 kHz provided in an embodiment of the present application;

[0059] Fig.10 This is a schematic diagram of the structure of a four-terminal flexible direct current system provided in an embodiment of the present application;

[0060] Fig.11a This is one of the simulation results before and after considering the high-frequency characteristics of the converter transformer provided in the embodiment of the present application;

[0061] Fig.11b The second simulation result before and after considering the high-frequency characteristics of the converter transformer provided in the embodiment of the present application;

[0062] Fig.12 This is one of the flow charts of the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar in an embodiment of the present application;

[0063] Fig.13 A flowchart for determining corresponding frequency response characteristics in an embodiment of the present application;

[0064] Fig.14 A flowchart of constructing a high-frequency model of a converter transformer in an embodiment of the present application;

[0065] Fig.15 A flowchart for determining high-frequency parameters of a converter transformer in an embodiment of the present application;

[0066] Fig.16 This is the second flow chart of the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar in an embodiment of the present application;

[0067] Fig.17 This is one of the structural diagrams of the high-frequency parameter extraction device of the converter transformer with high-frequency resonance of the hollow bus in the embodiment of the present application;

[0068] Fig.18 This is a structural diagram of a frequency characteristic determination unit in an embodiment of the present application;

[0069] Fig.19 This is a structural diagram of a high-frequency model building unit in an embodiment of the present application;

[0070] Fig. 20This is a structural diagram of a high-frequency parameter determination unit in an embodiment of the present application;

[0071] Fig.21 This is the second structural diagram of the high-frequency parameter extraction device of the converter transformer with high-frequency resonance of the hollow bus in the embodiment of the present application;

[0072] Fig. 22 It is a schematic diagram of the structure of an electronic device in an embodiment of the present application. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0074] The acquisition, storage, use and processing of data in the technical solution of this application comply with the relevant provisions of laws and regulations.

[0075] In one embodiment, see Fig.12 In order to fit the theoretical frequency response data of the converter transformer with the measured frequency response data based on the frequency response data of the converter transformer measured in the project, and then inversely obtain the high-frequency model parameters of the converter transformer, the present application provides a high-frequency parameter extraction method for a converter transformer with empty bus high-frequency resonance, including:

[0076] S101: determining a corresponding frequency response characteristic according to the acquired grid-side voltage data of the converter transformer;

[0077] S102: constructing a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics;

[0078] S103: Determine corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer.

[0079] It is understandable that when the flexible DC converter station operates with an empty busbar, the AC side is not connected to the AC system, and only the converter transformer operates without load. The high-frequency resonance under this condition is closely related to the high-frequency characteristics of the converter transformer. Only by establishing an accurate high-frequency model of the converter transformer can the high-frequency resonance of the empty busbar of the flexible DC converter station be correctly analyzed. At present, the converter transformer modeling for the high-frequency resonance of the empty busbar of the flexible DC system faces many problems, the main problems include:

[0080] 1. When using the existing method to analyze the high-frequency resonance of the flexible DC system, the converter transformer is only equivalent to the leakage inductance. This method only considers its power frequency characteristics, but ignores its high-frequency capacitance effect, and cannot perform high-frequency resonance analysis of the empty busbar of the flexible DC converter station.

[0081] 2. The high-frequency model parameters of existing transformers are obtained through electromagnetic field analysis calculation or experimental measurement. Electromagnetic field analysis calculation requires the structure, size, medium parameters and other data of the transformer to establish a detailed 3D finite element model. These data may not be available due to manufacturing confidentiality, and the numerical calculation itself is extremely complex, the experimental measurement operation is complicated, and the measured parameters are simplified, which can easily lead to inaccurate parameters.

[0082] When performing the high-frequency resonance analysis of the empty busbar of the flexible direct current converter station, the embodiment of the present application takes into account the capacitance effect of the high-frequency band of the converter transformer, establishes a high-frequency equivalent model of the converter transformer, and finds an efficient and accurate method for extracting the high-frequency model parameters of the converter transformer. Specifically, the capacitance effect of the high-frequency band of the converter transformer is taken into account, and a high-frequency equivalent model of the converter transformer is established. The improved Powell algorithm is used to fit the theoretical frequency response data of the transformer with the measured frequency response data of the transformer, and the high-frequency model parameters of the converter transformer are obtained by inverse calculation, thereby avoiding the problems of difficulty in establishing a 3D finite element model for electromagnetic field analysis and calculation, complex calculations, complex experimental measurement operations, and inaccurate parameters.

[0083] In view of this, the present application provides a method for constructing a high-frequency model and extracting parameters of a converter transformer for high-frequency resonance of an empty busbar in a flexible DC converter station. Figure 1 The specific steps include:

[0084] Step S1: by adding concentrated capacitance to the port of the power frequency model to represent the capacitance effect of the converter transformer, a high-frequency simplified model of the converter transformer is established, and the impedance of the grid-side port when the valve-side port of the established model is operated at no load is obtained;

[0085] Step S2: using a frequency sweep method to obtain the frequency response data of the converter transformer by actual measurement, and deriving the corresponding relationship between the frequency response characteristics of the converter transformer and its port impedance;

[0086] Step S3: using the improved Powell algorithm to fit the theoretical frequency response data of the converter transformer with the measured frequency response data, and inversely calculate and obtain the high-frequency equivalent model parameters of the converter transformer;

[0087] Step S4: verifying the extracted high-frequency model parameters of the converter transformer, and determining the applicable scope of establishing the high-frequency model of the converter transformer and the high-frequency model parameter extraction method.

[0088] The technical solution of the present invention is described in detail below in conjunction with specific embodiments.

[0089] First, the establishment of the high-frequency simplified model of the converter transformer and the acquisition of the grid-side port impedance when the valve side is unloaded are introduced in detail as follows.

[0090] (1) Low-frequency modeling of converter transformer

[0091] At low frequencies, the magnetic coupling between transformer coils plays a major role, and the properties of the transformer equivalent model are mainly determined by the inductance component. When analyzing transformers at low frequencies, the following methods are usually used: Figure 2 The inductance representation model of the ideal transformer is shown in Figure 1. Among them, L1 and L2 are the leakage inductance of the winding, L m is the excitation inductance, R1 and R2 are the equivalent resistances corresponding to copper loss, R m is the equivalent resistance corresponding to the iron loss, T is an ideal transformer with a transformation ratio of n1:n2, U1 and I1 are the grid-side input voltage and current of the converter transformer respectively; U2 and I2 are the valve-side input voltage and current of the converter transformer respectively.

[0092] (2) High-frequency equivalent modeling of converter transformer

[0093] As the frequency increases, especially when the frequency exceeds 1kHz, the physical characteristics of the transformer are significantly different from those at low frequencies, and the capacitance effect of the transformer gradually emerges. At this time, the traditional low-frequency model can no longer correctly reflect the high-frequency characteristics of the transformer, and the influence of the capacitance effect needs to be fully considered.

[0094] The converter transformer is installed between the AC grid and the valve side of the flexible DC converter station. It is usually considered as a whole during analysis, focusing on the voltage and current on the grid side and valve side of the converter transformer. In this embodiment of the application, the converter transformer is equivalent to a two-port network. The capacitance effect can be represented by five concentrated capacitance parameters, see Figure 3 As shown. Among them, C 1s and C 2s Represents the inter-turn capacitance of the grid-side and valve-side windings, C 10 and C 20 Represent the capacitance of the grid-side and valve-side windings to ground, respectively, and C 12 Represents the coupling capacitance between the grid side and valve side windings. L1 and L2 are the leakage inductances of the windings. m is the excitation inductance, R1 and R2 are the equivalent resistances corresponding to copper loss, R m is the equivalent resistance corresponding to the iron loss, T is an ideal transformer with a transformation ratio of n1:n2, U1 and I1 are the grid-side input voltage and current of the converter transformer respectively; U2 and I2 are the valve-side input voltage and current of the converter transformer respectively.

[0095] According to on-site analysis, the resonant frequency of high-frequency resonance in flexible DC systems is generally lower than 5kHz. Within this frequency range, the ground capacitance of the grid-side and valve-side windings of the converter transformer has little effect on its high-frequency impedance characteristics. Therefore, the ground capacitance of the grid-side and valve-side windings is ignored to obtain a simplified high-frequency model of the converter transformer, see Figure 4 As shown. Among them, C 1s and C 2s represents the turn-to-turn capacitance of the grid-side and valve-side windings, respectively, and C 12 represents the coupling capacitance between the grid side and valve side windings, L1 and L2 are the leakage inductances of the windings, and L m is the excitation inductance, R1 and R2 are the equivalent resistances corresponding to copper loss, R m is the equivalent resistance corresponding to the iron loss, T is an ideal transformer with a transformation ratio of n1:n2, U1 and I1 are the grid-side input voltage and current of the converter transformer respectively; U2 and I2 are the valve-side input voltage and current of the converter transformer respectively.

[0096] From the above description, it can be seen that the high-frequency parameter extraction method of the converter transformer with high-frequency resonance of the empty busbar provided in the present application can take into account the capacitance effect of the converter transformer in the high-frequency band, establish a high-frequency equivalent model of the converter transformer, and use the improved Powell algorithm to fit the theoretical frequency response data of the transformer with the measured frequency response data of the transformer, and inversely calculate the high-frequency model parameters of the converter transformer, thereby avoiding the problems of difficulty in establishing a finite element model for electromagnetic field analysis and calculation, complex calculations, complex experimental measurement operations, inaccurate parameters, etc.

[0097] In one embodiment, see Fig.13 , the grid-side voltage data includes a response terminal voltage and an excitation terminal voltage; the corresponding frequency response characteristics are determined according to the acquired grid-side voltage data of the converter transformer, including:

[0098] S201: applying a variable-frequency sinusoidal voltage excitation to a first terminal of a grid-side winding of a converter transformer, and connecting a matching resistor to a second terminal of the grid-side winding of the converter transformer; wherein two terminals of a valve-side winding of the converter transformer are suspended;

[0099] S202: Calculate the ratio of the response terminal voltage to the excitation terminal voltage at different frequencies to determine the frequency response characteristics of the transformer.

[0100] It can be understood that in order to determine the frequency response characteristics of the transformer, it is first necessary to solve the equivalent impedance of the grid-side port of the converter transformer.

[0101] Specifically, each branch of the model is represented by an impedance parameter, and the positive direction of the current in each branch is specified as follows: Figure 5As shown. Among them, U1 and I1 are the grid-side input voltage and current of the converter transformer respectively; U2 is the valve-side input voltage of the converter transformer; U0 and I0 are the grid-side voltage and current of the ideal transformer respectively; k is the ideal transformer ratio, i.e. n1:n2; Z1 and Z2 are the grid-side and valve-side winding leakage reactance of the converter transformer respectively; Z m is the impedance of the converter transformer excitation branch; Z 1s and Z 2s are the inter-turn capacitance and reactance of the grid-side and valve-side windings of the converter transformer respectively; Z 12 is the capacitive reactance of the coupling capacitor.

[0102] When the converter transformer valve side is running without load, according to Kirchhoff's voltage-current law, the input voltage and current relationship on the grid side is as follows:

[0103]

[0104] In the formula, U1 and I1 are the grid-side input voltage and current of the converter transformer respectively; U0 and I0 are the grid-side voltage and current of the ideal transformer respectively; k is the ideal transformer ratio, i.e. n1:n2; Z1 and Z2 are the grid-side and valve-side winding leakage reactance of the converter transformer respectively; Z m is the impedance of the converter transformer excitation branch; Z 1s and Z 2s are the inter-turn capacitance and reactance of the grid-side and valve-side windings of the converter transformer respectively; Z 12 is the capacitive reactance of the coupling capacitor.

[0105] Then, the grid-side port impedance of the converter transformer valve side when it is running without load is obtained as follows:

[0106]

[0107] In the formula,

[0108]

[0109] B=Z1(Z m +kZ 2s )+(Z1+Z m )[k 2 Z2+k(k-1)Z 2s ]

[0110] C=kZ 2s (Z1+Z m )

[0111]

[0112] E=(Z m +kZ 2s )[(k-1)Z 2s -Z 12]-(Z 12 +Z 2s )[k 2 Z2+k(k-1)Z 2s ]

[0113] F=(Z m +kZ 2s )(Z 12 +Z 2s )-kZ 2s (Z 12 +Z 2s )

[0114] Z1=R1+sL1;Z2=R2+sL2;

[0115]

[0116] It can be seen from formula (2) that the transformer equivalent impedance can be represented by the inductance, capacitance and resistance parameters in its high-frequency equivalent model.

[0117] Since the converter transformers in flexible DC projects are basically single-phase transformers, the embodiments of the present application mainly focus on the construction of high-frequency equivalent models of single-phase transformers, and do not consider the electromagnetic coupling effect between transformer phases.

[0118] In actual engineering, the frequency response characteristics of the converter transformer are obtained from the winding deformation test. The specific test principles and methods are described in detail below.

[0119] Furthermore, a method for obtaining the frequency response characteristics of the converter transformer is as follows.

[0120] As a passive linear two-port network, the internal characteristics of the transformer can be described by the transfer function (TF) H(jω) in the higher frequency range. If the inductance, capacitance and other parameters inside the transformer change, the zeros and poles of the equivalent network transfer function H(jω) will change, which will cause its frequency response characteristics to change. In actual engineering, the frequency response characteristics of the transformer can be described by Figure 6 The swept frequency method shown is obtained. Figure 6 Middle U s is a frequency-variable sinusoidal voltage excitation source, U0 is the response terminal voltage, R s is the excitation source resistance, R0 is the matching resistance of 50Ω, and I1 is the current flowing through the transformer winding. The specific operation of the frequency sweep method is as follows:

[0121] A variable frequency sinusoidal voltage excitation U is applied to one terminal of the transformer grid-side winding. s, the other terminal is connected to a 50Ω matching resistor R0, and the two terminals of the valve side winding are left hanging. Measure the voltage U0 across R0 and calculate the response terminal voltage U0 and the excitation terminal voltage U0 at different frequencies. i The frequency response characteristics of the transformer can be expressed as:

[0122]

[0123] Where U i (jω) is the excitation terminal voltage, and U0(jω) is the response terminal voltage.

[0124] The amplitude-frequency response characteristics are expressed in logarithmic form, then the amplitude-frequency characteristic M(jω) and the phase-frequency characteristic They can be expressed as:

[0125]

[0126] Where U i (jω) is the excitation terminal voltage, U0(jω) is the response terminal voltage, and are the phases of the excitation terminal voltage and the response terminal voltage respectively.

[0127] It can be seen from the above description that the high-frequency parameter extraction method of the converter transformer with empty bus high-frequency resonance provided in the present application can determine the corresponding frequency response characteristics according to the acquired grid-side voltage data of the converter transformer.

[0128] In one embodiment, see Fig.14 , the step of constructing a high-frequency model of a converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics comprises:

[0129] S301: Determine the equivalent impedance according to the grid-side current of the converter transformer, the response terminal voltage and the excitation terminal voltage;

[0130] S302: Determine the high-frequency model of the converter transformer according to the corresponding relationship between the equivalent impedance and the frequency response characteristic.

[0131] It can be understood that, next, a corresponding relationship between the frequency response characteristics of the converter transformer and the port impedance is established.

[0132] In actual projects, the transformer port impedance is generally not tested, but is reflected by the transformer frequency response characteristics. The transformer frequency response characteristics can be described by the ratio of the response terminal voltage to the excitation terminal voltage. Therefore, the derived transformer grid-side port impedance is further transformed. Figure 6 For the detection circuit shown, the terminal impedance of the transformer can be expressed as:

[0133]

[0134] Where U i (jω) is the excitation terminal voltage, U0(jω) is the response terminal voltage, and I1(jω) is the current flowing through the transformer winding.

[0135] The current flowing through the transformer winding is expressed as:

[0136]

[0137] Where U0(jω) is the response terminal voltage, and R0 is the matching resistor of 50Ω.

[0138] Substituting equation (6) into equation (5), we can get the corresponding relationship between the frequency response characteristics of the transformer and its port impedance as follows:

[0139]

[0140] In the formula, Z eq (jω) is the port impedance of the transformer, R0 is the matching resistor of 50Ω, is [R0+Z eq (jω)].

[0141] It can be seen from formula (7) that the frequency response characteristics of the transformer can be represented by its impedance. Therefore, by fitting the theoretical frequency response data of the transformer with the measured frequency response data of the transformer using the improved Powell algorithm, the high-frequency equivalent model parameters of the transformer can be obtained by inversion.

[0142] The improved Powell algorithm is a search method that uses the property that the conjugate direction can accelerate the convergence speed. It only needs to calculate the objective function to directly find the conjugate direction used for the search, which accelerates the convergence speed near the extreme point. It has the advantages of simple calculation, fast convergence speed, and high convergence accuracy. It is very suitable for solving the minimization problem of the objective function (quadratic function) established in the embodiment of the present application. The following will explain in detail how to extract the high-frequency model parameters of the converter transformer using the improved Powell algorithm.

[0143] From the above description, it can be seen that the high-frequency parameter extraction method of the converter transformer with empty bus high-frequency resonance provided in the present application can construct a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics.

[0144] In one embodiment, see Fig.15 , the determining of the corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer includes:

[0145] S401: Initializing a parameter set to be solved; wherein the parameter set is the optimal point obtained in each iteration;

[0146] S402: Based on a preset objective function, a parameter set obtained by inversion using the improved Powell algorithm is used as the optimal point obtained in the current round of iterations, and is compared with the optimal point obtained in the previous round of iterations;

[0147] S403: If the difference between the optimal point obtained in the current round of iterations and the optimal point obtained in the previous round of iterations meets the convergence condition or reaches the maximum number of iterations, the program is terminated; wherein the optimal point obtained in the current round of iterations is used as the high-frequency parameter of the converter transformer;

[0148] S404: Otherwise, reinitialize the parameter set, update the search direction group, and recalculate the optimal point of the objective function.

[0149] It can be understood that the specific steps of the inverse calculation of the high-frequency model parameters of the converter transformer are as follows:

[0150] Based on the measured frequency response amplitude and phase data of the converter transformer, the improved Powell algorithm is used to inversely calculate the parameters of the established high-frequency simplified model of the converter transformer.

[0151] In order to make the inversion calculation data fit better with the measured data, the algorithm objective function J is constructed. J represents the fitting degree of the measured and calculated data in the entire frequency range, which is expressed as follows:

[0152]

[0153] In the formula, [(TF) i ] measured and [(TF) i ] estimated are the measured and calculated frequency response data at frequency point i (including M(jω) and ), k is the number of frequency points taken. (|TF| i ) estimated It is calculated by equation (2) and equation (7).

[0154] The inverse calculation process of the high-frequency simplified model parameters of the converter transformer based on the improved Powell algorithm can be found in Figure 7 As shown, the main calculation steps are briefly described here.

[0155] ① Initialization: Establish a parameter set consisting of 9 parameters to be solved (R1, R2, L1, L2, L m , R m , C 1s , C 2s , C 12 ) is the optimal point in each iteration of the program;

[0156] ②Estimate: The parameter set inverted by the improved Powell algorithm is used as the optimal point obtained in this iteration and compared with the optimal point obtained in the previous iteration;

[0157] ③ Termination: The program is terminated when the difference between the optimal point obtained in this iteration and the optimal point obtained in the previous iteration meets the convergence condition or the maximum number of iterations is reached;

[0158] ④Update: When the termination condition is not met, update the initial point and search direction group, and use the golden section method to recalculate the optimal point of the objective function J.

[0159] It can be seen from the above description that the high-frequency parameter extraction method of the converter transformer with empty bus high-frequency resonance provided in the present application can determine the corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer.

[0160] In one embodiment, see Fig.16 , the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar further includes:

[0161] S501: Determine the calculated amplitude and calculated phase of the frequency response of the converter transformer by using the high frequency model of the converter transformer;

[0162] S502: Based on a preset error rate calculation function, the calculated amplitude and the calculated phase are compared with corresponding measured data to verify the accuracy of the high-frequency model of the converter transformer.

[0163] It can be understood that the accuracy evaluation process of the converter transformer high frequency model parameters is as follows.

[0164] Table 1 lists the high-frequency simplified model parameters of the flexible DC converter transformer obtained by inversion calculation using the improved Powell algorithm.

[0165] Table 1

[0166]

[0167] According to the parameters listed in Table 1, the amplitude and phase data of the converter transformer frequency response are calculated using equations (2) and (7) and compared with the measured data. The results are as follows: Figure 8a and Figure 8b As shown in Figure 2, the solid line represents the measured amplitude and phase, and the dotted line represents the calculated amplitude and phase. The degree of fit between the two can measure the accuracy of the converter transformer parameters obtained by inversion calculation.

[0168] The error rate can be used to measure the effect of transformer parameter fitting, and it is believed that the fitting effect is better when the error rate is within ±5%. Therefore, ±5% is taken as the maximum allowable error rate to meet the requirements of high-frequency resonance analysis of the empty busbar of the flexible DC converter station. The transformer parameter fitting error rate established is expressed as:

[0169]

[0170] Among them, [(H(jω)] measured and [(H(jω)] estimated The measured and calculated frequency response data are respectively. The amplitude error rate and phase error rate within 10kHz are as follows Figure 9a and Figure 9b shown.

[0171] Depend on Figure 9a and Figure 9b It can be seen that as the frequency increases, the amplitude and phase error rates continue to rise. At 5kHz, the amplitude error rate is 4.18% and the phase error rate is -4.98%, both of which are close to the upper limit of the allowable error. Therefore, below 5kHz, the calculated data has a high degree of fit with the measured data. Therefore, based on the constructed high-frequency simplified model of the converter transformer, the high-frequency model parameter extraction method of the converter transformer proposed in the present invention can more accurately obtain parameters such as turn-to-turn capacitance, coupling capacitance, leakage inductance, etc. within the frequency range of 5kHz, which can meet the requirements of high-frequency resonance analysis of flexible direct current empty busbars.

[0172] Furthermore, the effectiveness of the high-frequency model construction and parameter extraction method of the converter transformer for the high-frequency resonance of the empty busbar of the flexible DC converter station is verified by example.

[0173] Build an electromagnetic simulation model of a four-terminal flexible direct current system, see Fig.10 As shown, the system parameter settings are shown in Table 2. Among them, the flexible DC converter station MMC1 is the sending end converter station, the AC side is operated with empty busbar, and the power outer loop adopts V / f control strategy; the flexible DC converter station MMC2 power outer loop adopts constant DC voltage control strategy; the flexible DC converter station MMC3 and flexible DC converter station MMC4 power outer loop adopt constant power control strategy.

[0174] Table 2

[0175]

[0176] In the period of 0 to 2s, the converter transformer adopts the industrial frequency model. After 2s, it switches to the high frequency model established by the present invention. The simulated waveforms of the AC voltage and current on the grid side of the converter transformer are shown in Fig.11a and Fig.11b As shown. Fig.11a and Fig.11b It can be seen that the converter transformer adopts the industrial frequency model and the converter station operates stably. After switching to the high-frequency model established by the present invention and adopting the high-frequency model parameters (as shown in Table 1), the converter station and the converter transformer interact and high-frequency resonance occurs, proving that the high-frequency model of the converter transformer constructed by the present invention and the corresponding high-frequency model parameter extraction method are suitable for the analysis of the high-frequency resonance problem of the empty busbar of the flexible direct current converter station.

[0177] It can be seen from the above description that the high-frequency parameter extraction method of the converter transformer with high-frequency resonance of the empty bus provided in the present application can verify the accuracy of the high-frequency model of the converter transformer.

[0178] Based on the same inventive concept, the embodiments of the present application also provide a high-frequency parameter extraction device for a converter transformer with high-frequency resonance of an empty bus, which can be used to implement the method described in the above embodiments, as described in the following embodiments. Since the principle of solving the problem by the high-frequency parameter extraction device for a converter transformer with high-frequency resonance of an empty bus is similar to the high-frequency parameter extraction method for a converter transformer with high-frequency resonance of an empty bus, the implementation of the high-frequency parameter extraction device for a converter transformer with high-frequency resonance of an empty bus can refer to the implementation of the method based on software performance benchmark determination, and the repeated parts will not be repeated. As used below, the terms "unit" or "module" can be a combination of software and / or hardware that implements predetermined functions. Although the system described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0179] In one embodiment, see Fig.17 In order to fit the theoretical frequency response data of the converter transformer with the measured frequency response data based on the frequency response data of the converter transformer measured in the project, and then inversely obtain the high-frequency model parameters of the converter transformer, the present application provides a high-frequency parameter extraction device for a converter transformer with empty bus high-frequency resonance, including: a frequency characteristic determination unit 601, a high-frequency model construction unit 602 and a high-frequency parameter determination unit 603.

[0180] The frequency characteristic determination unit 601 is used to determine the corresponding frequency response characteristic according to the acquired grid-side voltage data of the converter transformer;

[0181] A high-frequency model building unit 602 is used to build a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics;

[0182] The high-frequency parameter determination unit 603 is used to determine the corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer.

[0183] In one embodiment, see Fig.18 , the grid-side voltage data includes the response end voltage and the excitation end voltage; the frequency characteristic determination unit 601 includes: a voltage excitation module 701 and a frequency characteristic determination module 702.

[0184] The voltage excitation module 701 is used to apply a variable-frequency sinusoidal voltage excitation to the first terminal of the grid-side winding of the converter transformer, and connect the second terminal of the grid-side winding of the converter transformer to a matching resistor; wherein the two terminals of the valve-side winding of the converter transformer are suspended;

[0185] The frequency characteristic determination module 702 is used to calculate the ratio of the response terminal voltage to the excitation terminal voltage at different frequencies to determine the frequency response characteristic of the transformer.

[0186] In one embodiment, see Fig.19 The high-frequency model building unit 602 includes: an equivalent impedance determination module 801 and a high-frequency model building module 802.

[0187] An equivalent impedance determination module 801 is used to determine the equivalent impedance according to the grid-side current of the converter transformer, the response terminal voltage and the excitation terminal voltage;

[0188] The high-frequency model building module 802 is used to determine the high-frequency model of the converter transformer according to the corresponding relationship between the equivalent impedance and the frequency response characteristic.

[0189] In one embodiment, see Fig. 20 The high frequency parameter determination unit 603 includes: a parameter initialization module 901, an iterative comparison module 902, a difference comparison module 903 and an adjustment calculation module 904.

[0190] The parameter initialization module 901 is used to initialize the parameter set to be solved; wherein the parameter set is the optimal point obtained in each iteration;

[0191] An iterative comparison module 902 is used to compare the parameter set obtained by inversion using the improved Powell algorithm as the optimal point obtained in the current round of iteration with the optimal point obtained in the previous round of iteration based on a preset objective function;

[0192] The difference comparison module 903 is used to terminate the program if the difference between the optimal point obtained in the current round of iteration and the optimal point obtained in the previous round of iteration meets the convergence condition or reaches the maximum number of iterations; wherein the optimal point obtained in the current round of iteration is used as the high-frequency parameter of the converter transformer;

[0193] The adjustment calculation module 904 is used to reinitialize the parameter set, update the search direction group, and recalculate the optimal point of the objective function.

[0194] In one embodiment, see Fig.21 , the high-frequency parameter extraction device for the converter transformer with high-frequency resonance of the empty busbar further includes:

[0195] An amplitude and phase unit 1001, used to determine the calculated amplitude and calculated phase of the frequency response of the converter transformer using the high frequency model of the converter transformer;

[0196] The model verification unit 1002 is used to compare the calculated amplitude and calculated phase with the corresponding measured data based on a preset error rate calculation function to verify the accuracy of the high-frequency model of the converter transformer.

[0197] From the hardware level, in order to fit the theoretical frequency response data of the converter transformer with the measured frequency response data based on the frequency response data of the converter transformer measured in the project, and then inversely obtain the high-frequency model parameters of the converter transformer, the present application provides an embodiment of an electronic device for implementing all or part of the contents of the high-frequency parameter extraction method of the converter transformer with high-frequency resonance of the empty bus, and the electronic device specifically includes the following contents:

[0198] Processor, memory, communication interface and bus; wherein the processor, memory and communication interface communicate with each other through the bus; the communication interface is used to realize information transmission between the high-frequency parameter extraction device of the converter transformer with high-frequency resonance of the empty bus and related equipment such as the core business system, user terminal and related database; the logic controller can be a desktop computer, a tablet computer and a mobile terminal, etc., and the present embodiment is not limited thereto. In the present embodiment, the logic controller can be implemented with reference to the embodiment of the high-frequency parameter extraction method of the converter transformer with high-frequency resonance of the empty bus and the embodiment of the high-frequency parameter extraction device of the converter transformer with high-frequency resonance of the empty bus, and the contents thereof are incorporated herein, and the repeated parts are not repeated.

[0199] It is understandable that the user terminal may include a smart phone, a tablet electronic device, a network set-top box, a portable computer, a desktop computer, a personal digital assistant (PDA), a vehicle-mounted device, a smart wearable device, etc. Among them, the smart wearable device may include smart glasses, a smart watch, a smart bracelet, etc.

[0200] In practical applications, part of the method for extracting high-frequency parameters of the converter transformer with high-frequency resonance of the empty busbar can be executed on the electronic device side as described above, or all operations can be completed in the client device. The selection can be made based on the processing capability of the client device and the limitations of the user's usage scenario. This application does not limit this. If all operations are completed in the client device, the client device may also include a processor.

[0201] The client device may have a communication module (i.e., a communication unit) that can communicate with a remote server to achieve data transmission with the server. The server may include a server on the task scheduling center side, and other implementation scenarios may also include a server on an intermediate platform, such as a server on a third-party server platform that has a communication link with the task scheduling center server. The server may include a single computer device, or a server cluster consisting of multiple servers, or a server structure of a distributed device.

[0202] Fig. 22 FIG. 9 is a schematic block diagram of the system structure of the electronic device 9600 according to an embodiment of the present application. Fig. 22 As shown, the electronic device 9600 may include a central processor 9100 and a memory 9140; the memory 9140 is coupled to the central processor 9100. It is worth noting that Fig. 22 is exemplary; other types of structures may also be used to supplement or replace this structure to implement telecommunication functions or other functions.

[0203] In one embodiment, the function of the high-frequency parameter extraction method of the converter transformer with high-frequency resonance of the empty busbar can be integrated into the central processor 9100. The central processor 9100 can be configured to perform the following control:

[0204] S101: determining a corresponding frequency response characteristic according to the acquired grid-side voltage data of the converter transformer;

[0205] S102: constructing a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics;

[0206] S103: Determine corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer.

[0207] From the above description, it can be seen that the high-frequency parameter extraction method of the converter transformer with high-frequency resonance of the empty busbar provided in the present application can take into account the capacitance effect of the converter transformer in the high-frequency band, establish a high-frequency equivalent model of the converter transformer, and use the improved Powell algorithm to fit the theoretical frequency response data of the transformer with the measured frequency response data of the transformer, and inversely calculate the high-frequency model parameters of the converter transformer, thereby avoiding the problems of difficulty in establishing a finite element model for electromagnetic field analysis and calculation, complex calculations, complex experimental measurement operations, inaccurate parameters, etc.

[0208] In another embodiment, the high-frequency parameter extraction device for the converter transformer with high-frequency resonance of the empty busbar can be configured separately from the central processing unit 9100. For example, the high-frequency parameter extraction device for the converter transformer with high-frequency resonance of the empty busbar of the data composite transmission device can be configured as a chip connected to the central processing unit 9100, and the function of the high-frequency parameter extraction method for the converter transformer with high-frequency resonance of the empty busbar can be realized through the control of the central processing unit.

[0209] like Fig. 22 As shown, the electronic device 9600 may also include: a communication module 9110, an input unit 9120, an audio processor 9130, a display 9160, and a power supply 9170. It is worth noting that the electronic device 9600 does not necessarily have to include Fig. 22 In addition, the electronic device 9600 may also include Fig. 22 For components not shown, reference may be made to the prior art.

[0210] like Fig. 22 As shown, the central processing unit 9100 is sometimes also referred to as a controller or an operation control, and may include a microprocessor or other processor device and / or logic device. The central processing unit 9100 receives input and controls the operation of various components of the electronic device 9600.

[0211] The memory 9140 may be, for example, one or more of a cache, a flash memory, a hard drive, a removable medium, a volatile memory, a non-volatile memory or other suitable devices. The above-mentioned information related to the failure may be stored, and a program for executing the relevant information may also be stored. The CPU 9100 may execute the program stored in the memory 9140 to implement information storage or processing, etc.

[0212] The input unit 9120 provides input to the central processing unit 9100. The input unit 9120 is, for example, a key or a touch input device. The power supply 9170 is used to provide power to the electronic device 9600. The display 9160 is used to display display objects such as images and texts. The display may be, for example, an LCD display, but is not limited thereto.

[0213] The memory 9140 may be a solid-state memory, such as a read-only memory (ROM), a random access memory (RAM), a SIM card, etc. It may also be a memory that saves information even when the power is off, can be selectively erased, and is provided with more data, examples of which are sometimes referred to as EPROMs, etc. The memory 9140 may also be some other type of device. The memory 9140 includes a buffer memory 9141 (sometimes referred to as a buffer). The memory 9140 may include an application / function storage unit 9142, which is used to store application programs and function programs or processes for executing the operation of the electronic device 9600 through the central processor 9100.

[0214] The memory 9140 may also include a data storage unit 9143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 9144 of the memory 9140 may include various drivers for communication functions of the electronic device and / or for executing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0215] The communication module 9110 is a transmitter / receiver that sends and receives signals via the antenna 9111. The communication module (transmitter / receiver) 9110 is coupled to the central processor 9100 to provide input signals and receive output signals, which may be the same as the case of a conventional mobile communication terminal.

[0216] Based on different communication technologies, multiple communication modules 9110 may be provided in the same electronic device, such as a cellular network module, a Bluetooth module and / or a wireless LAN module. The communication module (transmitter / receiver) 9110 is also coupled to a speaker 9131 and a microphone 9132 via an audio processor 9130 to provide an audio output via the speaker 9131 and receive an audio input from the microphone 9132, thereby realizing a common telecommunication function. The audio processor 9130 may include any suitable buffer, decoder, amplifier, etc. In addition, the audio processor 9130 is also coupled to the central processor 9100, so that recording can be performed on the local machine through the microphone 9132, and the sound stored on the local machine can be played through the speaker 9131.

[0217] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps in the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar, in which the execution subject is a server or a client in the above embodiments. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, all the steps in the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar, in which the execution subject is a server or a client in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0218] S101: determining a corresponding frequency response characteristic according to the acquired grid-side voltage data of the converter transformer;

[0219] S102: constructing a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics;

[0220] S103: Determine corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer.

[0221] From the above description, it can be seen that the high-frequency parameter extraction method of the converter transformer with high-frequency resonance of the empty busbar provided in the present application can take into account the capacitance effect of the converter transformer in the high-frequency band, establish a high-frequency equivalent model of the converter transformer, and use the improved Powell algorithm to fit the theoretical frequency response data of the transformer with the measured frequency response data of the transformer, and inversely calculate the high-frequency model parameters of the converter transformer, thereby avoiding the problems of difficulty in establishing a finite element model for electromagnetic field analysis and calculation, complex calculations, complex experimental measurement operations, inaccurate parameters, etc.

[0222] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0223] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (apparatus), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0224] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0225] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0226] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar, characterized in that: include: Determine the corresponding frequency response characteristics according to the acquired grid-side voltage data of the converter transformer; Constructing a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics; The corresponding high-frequency parameters of the converter transformer are determined based on the high-frequency model of the converter transformer.

2. The high-frequency parameter extraction method of the converter transformer with empty bus high-frequency resonance according to claim 1 is characterized in that: The grid-side voltage data includes a response terminal voltage and an excitation terminal voltage; the corresponding frequency response characteristics are determined according to the acquired grid-side voltage data of the converter transformer, including: Apply a variable frequency sinusoidal voltage excitation to the first terminal of the grid-side winding of the converter transformer, and connect the second terminal of the grid-side winding of the converter transformer to a matching resistor; wherein the two terminals of the valve-side winding of the converter transformer are suspended; The ratio of the response terminal voltage to the excitation terminal voltage at different frequencies is calculated to determine the frequency response characteristics of the transformer.

3. The high-frequency parameter extraction method of the converter transformer with empty bus high-frequency resonance according to claim 2 is characterized in that: The step of constructing a high-frequency model of a converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics includes: Determine the equivalent impedance according to the grid-side current of the converter transformer, the response terminal voltage and the excitation terminal voltage; The converter transformer high frequency model is determined according to the corresponding relationship between the equivalent impedance and the frequency response characteristic.

4. The high-frequency parameter extraction method of the converter transformer with empty bus high-frequency resonance according to claim 1 is characterized in that: The determining the corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer includes: Initialize the parameter set to be solved; wherein the parameter set is the optimal point obtained in each iteration; Based on the preset objective function, the parameter set obtained by inversion using the improved Powell algorithm is used as the optimal point obtained in the current round of iterations and compared with the optimal point obtained in the previous round of iterations; If the difference between the optimal point obtained in the current round of iteration and the optimal point obtained in the previous round of iteration meets the convergence condition or reaches the maximum number of iterations, the program is terminated; wherein the optimal point obtained in the current round of iteration is used as the high-frequency parameter of the converter transformer; Otherwise, the parameter set is reinitialized, the search direction group is updated, and the optimal point of the objective function is recalculated.

5. The high-frequency parameter extraction method for converter transformer with empty bus high-frequency resonance according to claim 1 is characterized in that: Also includes: Determining the calculated amplitude and calculated phase of the frequency response of the converter transformer by using the converter transformer high frequency model; Based on a preset error rate calculation function, the calculated amplitude and calculated phase are compared with corresponding measured data to verify the accuracy of the high-frequency model of the converter transformer.

6. A high-frequency parameter extraction device for a converter transformer with empty bus high-frequency resonance, characterized in that: include: A frequency characteristic determination unit, used to determine a corresponding frequency response characteristic according to the acquired grid-side voltage data of the converter transformer; A high-frequency model building unit, used to build a high-frequency model of the converter transformer according to the predetermined equivalent impedance of the grid-side port of the converter transformer and the frequency response characteristics; A high-frequency parameter determination unit is used to determine the corresponding high-frequency parameters of the converter transformer based on the high-frequency model of the converter transformer.

7. The high-frequency parameter extraction device for converter transformer with empty bus high-frequency resonance according to claim 6 is characterized in that: The grid-side voltage data includes a response terminal voltage and an excitation terminal voltage; the frequency characteristic determination unit includes: A voltage excitation module, used for applying a variable-frequency sinusoidal voltage excitation to the first terminal of the grid-side winding of the converter transformer, and connecting the second terminal of the grid-side winding of the converter transformer to a matching resistor; wherein the two terminals of the valve-side winding of the converter transformer are suspended; The frequency characteristic determination module is used to calculate the ratio of the response terminal voltage to the excitation terminal voltage at different frequencies to determine the frequency response characteristic of the transformer.

8. The high-frequency parameter extraction device for converter transformer with empty bus high-frequency resonance according to claim 7 is characterized in that: The high-frequency model building unit comprises: An equivalent impedance determination module, used to determine the equivalent impedance according to the grid-side current of the converter transformer, the response terminal voltage and the excitation terminal voltage; A high-frequency model building module is used to determine the high-frequency model of the converter transformer according to the corresponding relationship between the equivalent impedance and the frequency response characteristic.

9. The high-frequency parameter extraction device for converter transformer with empty bus high-frequency resonance according to claim 6 is characterized in that: The high frequency parameter determination unit comprises: A parameter initialization module is used to initialize the parameter set to be solved; wherein the parameter set is the optimal point obtained in each iteration; An iterative comparison module is used to compare the parameter set obtained by inversion using the improved Powell algorithm as the optimal point obtained in the current round of iterations with the optimal point obtained in the previous round of iterations based on a preset objective function; A difference comparison module is used to terminate the program if the difference between the optimal point obtained in the current round of iteration and the optimal point obtained in the previous round of iteration meets the convergence condition or reaches the maximum number of iterations; wherein the optimal point obtained in the current round of iteration is used as the high-frequency parameter of the converter transformer; The calculation module is adjusted to reinitialize the parameter set, update the search direction group, and recalculate the optimal point of the objective function.

10. The high-frequency parameter extraction device for converter transformer with empty bus high-frequency resonance according to claim 6, characterized in that: Also includes: An amplitude and phase module, used to determine the calculated amplitude and calculated phase of the frequency response of the converter transformer using the high-frequency model of the converter transformer; The model verification module is used to compare the calculated amplitude and calculated phase with the corresponding measured data based on a preset error rate calculation function to verify the accuracy of the high-frequency model of the converter transformer.

11. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method for extracting high-frequency parameters of a converter transformer with empty bus high-frequency resonance as described in any one of claims 1 to 5 are implemented.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar are implemented as described in any one of claims 1 to 5.

13. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the steps of the method for extracting high-frequency parameters of a converter transformer with high-frequency resonance of an empty busbar are implemented as described in any one of claims 1 to 5.

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