Frequency dependent impedance modeling method, device and equipment of power transmission line and medium

Abstract

The invention relates to the technical field of power system modeling analysis, in particular to a frequency dependent impedance modeling method, device and equipment of a power transmission line and a medium. The method comprises the steps of obtaining resistance values and inductance values of a power transmission line at multiple frequency points, performing polynomial fitting on the resistance values and the inductance values at the multiple frequency points, and establishing an impedance model of the power transmission line based on an obtained frequency response fitting result of resistance and inductance of the power transmission line. Therefore, by comprehensively considering the distribution parameter characteristics and frequency correlation of the power transmission line, a model capable of accurately describing the impedance characteristics of the power transmission line under different frequencies is constructed, and the problem that the impedance characteristics of the power transmission line under different frequencies cannot be accurately described because only the distribution parameter characteristics of the power transmission line are simulated in the prior art is solved. The method solves the problem that limitation exists due to the fact that the frequency correlation of power transmission line parameters is not considered, improves the accuracy of power transmission line impedance modeling, and provides a theoretical basis for power system oscillation stability analysis.

Description

Technical Field

[0001] The present application relates to the technical field of power system modeling and analysis, and in particular to a method, device, equipment and medium for modeling frequency-dependent impedance of a transmission line. Background Art

[0002] The interaction between transmission lines and grid-connected inverters in power systems may cause unstable oscillation risks. Accurate modeling of transmission lines is of great significance for oscillation analysis and evaluation. Transmission lines not only have distributed parameter characteristics, but also have frequency-dependent characteristics of line resistance and inductance due to skin effect and proximity effect.

[0003] In the related art, commonly used models include the Bergeron model and the series π model.

[0004] However, the above model can only simulate the distributed parameter characteristics of the transmission line, without considering the frequency correlation of the transmission line parameters, resulting in limitations that need to be solved urgently. Summary of the invention

[0005] The present application provides a method, device, equipment and medium for frequency-dependent impedance modeling of a transmission line to solve the problem that the prior art has limitations due to only simulating the distributed parameter characteristics of the transmission line without considering the frequency correlation of the transmission line parameters, thereby improving the accuracy of transmission line impedance modeling and providing a theoretical basis for power system oscillation stability analysis.

[0006] To achieve the above-mentioned object, the first embodiment of the present application proposes a method for modeling frequency-dependent impedance of a transmission line, comprising the following steps:

[0007] Obtain the resistance value of the transmission line at multiple frequency points and the inductance value at multiple frequency points;

[0008] Performing polynomial fitting on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points to obtain a frequency response fitting result of the resistance and inductance of the transmission line;

[0009] Based on the frequency response fitting result of the resistance and inductance of the transmission line, an impedance model of the transmission line is established.

[0010] According to an embodiment of the present application, performing polynomial fitting on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points to obtain a frequency response fitting result of the resistance and inductance of the transmission line includes:

[0011] Based on the least squares method strategy, polynomial fitting is performed on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points respectively, an initial fitting result and a root mean square error corresponding to the initial fitting result are obtained, and a current fitting order of the polynomial is recorded;

[0012] Based on the initial fitting result, determining whether a root mean square error corresponding to the initial fitting result is less than or equal to a preset error threshold;

[0013] If the root mean square error corresponding to the initial fitting result is less than or equal to the preset error threshold, the initial fitting result is used as the frequency response fitting result of the transmission line inductance; otherwise, the current fitting order is iteratively increased according to a preset rule until the root mean square error corresponding to the new initial fitting result is less than or equal to the preset error threshold.

[0014] According to an embodiment of the present application, establishing the impedance model of the transmission line based on the frequency response fitting result of the resistance and inductance of the transmission line includes:

[0015] Based on the frequency response fitting result of the resistance and inductance of the transmission line, and according to the preset relationship between the voltage and current at the head end and the end end of the transmission line, a transmission line model considering the frequency correlation of parameters is obtained;

[0016] Based on the transmission line model that takes into account the frequency correlation of parameters, an impedance model of the transmission line is established according to the end state of the transmission line, wherein the end state of the transmission line includes the end connection impedance of the transmission line, the end grounding of the transmission line and the end open circuit of the transmission line.

[0017] According to one embodiment of the present application, when the end of the transmission line is connected to an impedance, the impedance model of the transmission line is:

[0018]

[0019] Among them, Z line is the impedance model of the transmission line, Z g is the impedance of the end connection of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0020] According to one embodiment of the present application, when the end of the transmission line is grounded, the impedance model of the transmission line is:

[0021]

[0022] Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0023] According to one embodiment of the present application, when the end of the transmission line is open, the impedance model of the transmission line is:

[0024]

[0025] Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0026] According to the frequency-dependent impedance modeling method of the transmission line proposed in the embodiment of the present application, by obtaining the resistance value of the transmission line at multiple frequency points and the inductance value at multiple frequency points, and performing polynomial fitting on the resistance value at multiple frequency points and the inductance value at multiple frequency points, the impedance model of the transmission line can be established based on the obtained frequency response fitting results of the resistance and inductance of the transmission line. Thus, by comprehensively considering the distributed parameter characteristics and frequency correlation of the transmission line, a model that can accurately describe the impedance characteristics of the transmission line at different frequencies is constructed, which solves the problem that the prior art has limitations due to only simulating the distributed parameter characteristics of the transmission line and not considering the frequency correlation of the transmission line parameters, improves the accuracy of the transmission line impedance modeling, and provides a theoretical basis for the oscillation stability analysis of the power system.

[0027] To achieve the above-mentioned purpose, a second embodiment of the present application provides a frequency-dependent impedance modeling device for a transmission line, comprising:

[0028] An acquisition module, used to acquire resistance values ​​of a transmission line at multiple frequency points and inductance values ​​at multiple frequency points;

[0029] A fitting module, used to perform polynomial fitting on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points to obtain a frequency response fitting result of the resistance and inductance of the transmission line;

[0030] An establishing module is used to establish an impedance model of the transmission line based on a frequency response fitting result of the resistance and inductance of the transmission line.

[0031] According to one embodiment of the present application, the fitting module is specifically used for:

[0032] Based on the least squares method strategy, polynomial fitting is performed on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points respectively, an initial fitting result and a root mean square error corresponding to the initial fitting result are obtained, and a current fitting order of the polynomial is recorded;

[0033] Based on the initial fitting result, determining whether a root mean square error corresponding to the initial fitting result is less than or equal to a preset error threshold;

[0034] If the root mean square error corresponding to the initial fitting result is less than or equal to the preset error threshold, the initial fitting result is used as the frequency response fitting result of the transmission line inductance; otherwise, the current fitting order is iteratively increased according to a preset rule until the root mean square error corresponding to the new initial fitting result is less than or equal to the preset error threshold.

[0035] According to one embodiment of the present application, the establishment module is specifically used to:

[0036] Based on the frequency response fitting result of the resistance and inductance of the transmission line, and according to the preset relationship between the voltage and current at the head end and the end end of the transmission line, a transmission line model considering the frequency correlation of parameters is obtained;

[0037] Based on the transmission line model that takes into account the frequency correlation of parameters, an impedance model of the transmission line is established according to the end state of the transmission line, wherein the end state of the transmission line includes the end connection impedance of the transmission line, the end grounding of the transmission line and the end open circuit of the transmission line.

[0038] According to one embodiment of the present application, when the end of the transmission line is connected to an impedance, the impedance model of the transmission line is:

[0039]

[0040] Among them, Z line is the impedance model of the transmission line, Z g is the impedance of the end connection of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0041] According to one embodiment of the present application, when the end of the transmission line is grounded, the impedance model of the transmission line is:

[0042]

[0043] Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0044] According to one embodiment of the present application, when the end of the transmission line is open, the impedance model of the transmission line is:

[0045]

[0046] Among them, Z lineis the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0047] According to the frequency-dependent impedance modeling device of the transmission line proposed in the embodiment of the present application, by obtaining the resistance value of the transmission line at multiple frequency points and the inductance value at multiple frequency points, and performing polynomial fitting on the resistance value at multiple frequency points and the inductance value at multiple frequency points, the impedance model of the transmission line can be established based on the obtained frequency response fitting results of the resistance and inductance of the transmission line. Therefore, by comprehensively considering the distributed parameter characteristics and frequency correlation of the transmission line, a model that can accurately describe the impedance characteristics of the transmission line at different frequencies is constructed, which solves the problem that the prior art has limitations due to only simulating the distributed parameter characteristics of the transmission line and not considering the frequency correlation of the transmission line parameters, improves the accuracy of the transmission line impedance modeling, and provides a theoretical basis for the oscillation stability analysis of the power system.

[0048] To achieve the above-mentioned objectives, the third aspect embodiment of the present application proposes an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the frequency-dependent impedance modeling method of the transmission line as described in the above-mentioned embodiment.

[0049] To achieve the above objectives, the fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the frequency-dependent impedance modeling method of the transmission line as described in the above embodiments.

[0050] To achieve the above objectives, a fifth aspect of the present application provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it is used to implement the frequency-dependent impedance modeling method of the transmission line as described in the above embodiments.

[0051] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0053] Figure 1 A flowchart of a method for modeling frequency-dependent impedance of a power transmission line provided according to an embodiment of the present application;

[0054] Figure 2A block diagram of a frequency-dependent impedance modeling device for a power transmission line provided according to an embodiment of the present application;

[0055] Figure 3 It is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0056] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0057] The following describes a method, apparatus, device and medium for modeling frequency-dependent impedance of a power transmission line according to an embodiment of the present application with reference to the accompanying drawings.

[0058] Figure 1 It is a flow chart of a method for modeling frequency-dependent impedance of a transmission line according to an embodiment of the present application.

[0059] For example, Figure 1 As shown, the frequency-dependent impedance modeling method of the transmission line includes the following steps:

[0060] In step S101, the resistance value of the power transmission line at multiple frequency points and the inductance value at multiple frequency points are obtained.

[0061] Among them, transmission lines refer to facilities in the power system used to transmit electrical energy over long distances, usually including high-voltage transmission lines, towers, etc.

[0062] That is, by obtaining the resistance values ​​of the transmission line at a plurality of different frequency points and the inductance values ​​at these frequency points, the resistance and inductance characteristics of the transmission line at different frequencies can be obtained.

[0063] Specifically, in the frequency range of interest [f min ,f max ], k frequency points f can be selected i (i=1,2,...,k), and when making this selection, it is necessary to ensure that the number of these frequency points k is greater than the order of the polynomial fitting to be performed in the subsequent steps. Since polynomial fitting requires sufficient data points to ensure the accuracy and reliability of the fitting, preferably, the number of selected frequency points k can be greater than or equal to 5 to ensure that the fitting process has sufficient data support.

[0064] It is understandable that although increasing the number of frequency points can improve the accuracy of fitting, too many frequency points will also lead to a significant increase in the measurement workload. Therefore, when determining the number of frequency points, the number of frequency points k should not be too large to avoid unnecessary measurement burden and data processing complexity. By reasonably selecting the number and distribution of frequency points, the workload of measurement and calculation can be effectively controlled while ensuring the quality of fitting.

[0065] Furthermore, the resistance and inductance values ​​of the transmission line at multiple frequency points can be obtained in the following two ways: (1) If the measured data of the resistance and inductance of the same type of transmission line can be obtained in actual engineering, the required parameter values ​​can be directly obtained based on these data. These measured data usually come from detailed measurements of existing transmission lines, and these measurement results can accurately reflect the resistance and inductance characteristics of the line at different frequencies. In this way, it can be ensured that the obtained parameter values ​​have high practical application value and accuracy.

[0066] However, in some cases, when it is impossible to directly obtain the measured data of the transmission line parameters in the actual project, another method can be used: (2) build a transmission line model of the same type as the actual project in the electromagnetic transient simulation software to simulate the actual transmission line in the software environment and set a series of frequency values ​​f i (where i = 1, 2, ..., k), and conduct simulation tests at different frequencies to measure the line resistance and inductance values ​​at these frequencies in the simulation software. In this way, the resistance and inductance parameter values ​​of the transmission line at different frequencies can be obtained without actual measurement data.

[0067] In step S102, polynomial fitting is performed on the resistance values ​​at multiple frequency points and the inductance values ​​at multiple frequency points to obtain a frequency response fitting result of the resistance and inductance of the transmission line.

[0068] That is to say, by measuring and recording the resistance values ​​at multiple different frequency points in detail, the polynomial fitting method can be used to analyze and process these data. Similarly, for the inductance values ​​at multiple different frequency points, similar polynomial fitting can be performed. Through this mathematical modeling method, the law of the change of resistance and inductance in the transmission line with frequency can be obtained, thereby obtaining the fitting result of the frequency response of the resistance and inductance of the transmission line. The fitting result helps to better understand the electrical characteristics of the transmission line at different frequencies, and provides an important reference for the optimization design and fault analysis of the power system.

[0069] For ease of understanding, the following describes in detail how to perform polynomial fitting on resistance values ​​at multiple frequency points and inductance values ​​at multiple frequency points to obtain frequency response fitting results of transmission line resistance and inductance.

[0070] As a possible implementation method, in some embodiments, polynomial fitting is performed on the resistance values ​​at multiple frequency points and the inductance values ​​at multiple frequency points to obtain the frequency response fitting result of the resistance and inductance of the transmission line, including: based on the least squares strategy, polynomial fitting is performed on the resistance values ​​at multiple frequency points and the inductance values ​​at multiple frequency points respectively to obtain the initial fitting result and the root mean square error corresponding to the initial fitting result, and the current fitting order of the polynomial is recorded; based on the initial fitting result, it is determined whether the root mean square error corresponding to the initial fitting result is less than or equal to the preset error threshold; if the root mean square error corresponding to the initial fitting result is less than or equal to the preset error threshold, the initial fitting result is used as the frequency response fitting result of the resistance and inductance of the transmission line, otherwise, the current fitting order is iteratively increased according to the preset rule until the root mean square error corresponding to the new initial fitting result is less than or equal to the preset error threshold.

[0071] It should be noted that when analyzing the transmission line, considering the influence of skin effect and proximity effect on the resistance and inductance of the transmission line, in order to accurately describe this influence, the resistance R and inductance L of the transmission line can be expressed as a function of the square root of the frequency. Among them, the skin effect refers to the phenomenon that the AC current is unevenly distributed inside the conductor and is mainly concentrated on the surface of the conductor; the proximity effect refers to the fact that when two or more conductors are close, the distribution of current in these conductors will be affected by each other. Both effects will have a significant impact on the resistance and inductance of the transmission line.

[0072] Specifically, based on the least squares method, polynomial fitting is performed on the resistance value R at multiple frequency points and the inductance value L at multiple frequency points, and the fitting expression is as follows:

[0073]

[0074] Among them, R(ω) is the initial fitting result of resistance, L(ω) is the initial fitting result of inductance, ω is the angular frequency, n is the fitting order of the polynomial of resistance, m is the fitting order of the polynomial of inductance, and a i is the coefficient of the resistance fitting polynomial, b i are the coefficients of the inductance fitting polynomial.

[0075] In the process of data fitting, in order to evaluate the accuracy of the initial fitting results, the performance of the fitting model can be evaluated by calculating the root mean square error corresponding to each fitting result (a method to measure the difference between the model prediction value and the actual observation value, which can be obtained by averaging the square of the error and then taking the square root), thereby providing a basis for further analysis and optimization.

[0076] First, an error threshold is set, and the preset error threshold is the maximum acceptable error range. By calculating the root mean square error corresponding to the current fitting result, it can be determined whether the fitting result meets the accuracy requirements. If the calculated root mean square error corresponding to the current fitting result is greater than the preset error threshold, it indicates that the fitting effect of the current model is not ideal and cannot meet the accuracy requirements. Then in order to improve the fitting accuracy of the model, measures can be taken to increase the fitting order of the polynomial, that is, increase the fitting order of the polynomial by one order, and then re-perform the fitting process, and so on, until the accuracy requirements are met, that is, the calculated root mean square error corresponding to the current fitting result is not greater than the preset error threshold.

[0077] It is understandable that the order of the polynomial determines the complexity of the model. The higher the order, the stronger the model's fitting ability, but it may also lead to overfitting. Therefore, in actual operation, a balance can be found between the fitting ability and the generalization ability of the model, and a suitable fitting order can be selected. Preferably, the embodiment of the present application selects a fitting order of 3 to 4.

[0078] Therefore, by gradually increasing the fitting order of the polynomial and calculating the root mean square error, the model can be continuously optimized until the preset accuracy standard is reached.

[0079] In step S103, an impedance model of the transmission line is established based on the frequency response fitting result of the resistance and inductance of the transmission line.

[0080] That is to say, through a detailed fitting analysis of the frequency response of the resistance and inductance of the transmission line, an accurate transmission line impedance model can be further constructed. This model will be based on actual measurement data, take into account the resistance and inductance characteristics of the line, and fit its frequency response curve through mathematical methods. In this way, the impedance characteristics of the transmission line at different frequencies can be more accurately described, thus providing an important reference for the stable operation and fault analysis of the power system.

[0081] Next, we will explain in detail how to establish the impedance model of the transmission line based on the frequency response fitting results of the transmission line resistance and inductance.

[0082] As a possible implementation method, in some embodiments, an impedance model of a transmission line is established based on a frequency response fitting result of the resistance and inductance of the transmission line, including: based on the frequency response fitting result of the resistance and inductance of the transmission line, according to a preset relationship between the voltage and current at the head end and the end end of the transmission line, a transmission line model that considers the frequency correlation of parameters is obtained; based on the transmission line model that considers the frequency correlation of parameters, according to the end state of the transmission line, an impedance model of the transmission line is established, wherein the end state of the transmission line includes the end connection impedance of the transmission line, the end grounding of the transmission line, and the end open circuit of the transmission line.

[0083] Specifically, by accurately fitting the frequency response of the transmission line impedance and inductance, we can further understand the behavioral characteristics of the transmission line at different frequencies. Based on this fitting result, combined with the preset relationship between the voltage and current at the beginning and end of the transmission line, a transmission line model that considers the frequency correlation of parameters can be obtained. Among them, the preset relationship between the voltage and current at the beginning and end of the transmission line is shown in the following formula:

[0084]

[0085] in,

[0086] Z(ω)=R(ω)+jωL(ω); (4)

[0087] Y(ω)=jωC; (5)

[0088] in, is the voltage at the beginning of the transmission line, is the current at the beginning of the transmission line, is the voltage at the end of the transmission line, is the current at the end of the transmission line, l is the length of the transmission line, Z(ω) is the impedance of the transmission line per unit length, the resistance R(ω) and inductance L(ω) are frequency-dependent, Y(ω) is the admittance of the transmission line per unit length, the capacitance C is independent of frequency, j is the imaginary sign of the complex number, sinh(·) is the hyperbolic sine function, and cosh(·) is the hyperbolic cosine function.

[0089] Substituting equations (1) and (2) into equation (3), we can obtain a transmission line model that takes into account the frequency correlation of parameters.

[0090] Based on the transmission line model considering the frequency correlation of parameters, the impedance model of the transmission line can be further established according to the specific state of the end of the transmission line. The following will be described in detail according to the specific state of the end of the transmission line.

[0091] Optionally, in some embodiments, when the end of the transmission line is connected to an impedance, the impedance model of the transmission line is:

[0092]

[0093] Among them, Z line is the impedance model of the transmission line, Z g is the impedance of the end connection of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, l is the length of the transmission line, and tanh(·) is the hyperbolic tangent function.

[0094] That is, if the impedance of the end connection of the transmission line is Zg (impedance characteristics of the equipment or load connected at the end of the transmission line), the voltage and current at the end of the transmission line satisfy:

[0095]

[0096] Combining the transmission line model that considers the frequency correlation of parameters and equation (7), the impedance model of the transmission line viewed from the head end of the line can be obtained as shown in equation (6).

[0097] Optionally, in some embodiments, when the end of the transmission line is grounded, the impedance model of the transmission line is:

[0098]

[0099] Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0100] That is to say, if the end of the transmission line is grounded, combined with the transmission line model that considers the frequency correlation of parameters, the impedance model of the transmission line viewed from the head end of the transmission line can be obtained as shown in formula (8).

[0101] Optionally, in some embodiments, when the end of the transmission line is open, the impedance model of the transmission line is:

[0102]

[0103] Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0104] That is to say, if the end of the transmission line is open, combined with the transmission line model that considers the frequency correlation of parameters, the impedance model of the transmission line viewed from the head end of the transmission line can be obtained as shown in formula (9).

[0105] According to the frequency-dependent impedance modeling method of the transmission line proposed in the embodiment of the present application, by obtaining the resistance value of the transmission line at multiple frequency points and the inductance value at multiple frequency points, and performing polynomial fitting on the resistance value at multiple frequency points and the inductance value at multiple frequency points, the impedance model of the transmission line can be established based on the obtained frequency response fitting results of the resistance and inductance of the transmission line. Thus, by comprehensively considering the distributed parameter characteristics and frequency correlation of the transmission line, a model that can accurately describe the impedance characteristics of the transmission line at different frequencies is constructed, which solves the problem that the prior art has limitations due to only simulating the distributed parameter characteristics of the transmission line and not considering the frequency correlation of the transmission line parameters, improves the accuracy of the transmission line impedance modeling, and provides a theoretical basis for the oscillation stability analysis of the power system.

[0106] Next, a frequency-dependent impedance modeling device for a power transmission line proposed in an embodiment of the present application will be described with reference to the accompanying drawings.

[0107] Figure 2 It is a block diagram of a frequency-dependent impedance modeling device for a transmission line according to an embodiment of the present application.

[0108] like Figure 2 As shown, the frequency-dependent impedance modeling device 10 for a transmission line includes: an acquisition module 100 , a fitting module 200 and a building module 300 .

[0109] The acquisition module 100 is used to acquire the resistance value of the transmission line at multiple frequency points and the inductance value at multiple frequency points;

[0110] The fitting module 200 is used to perform polynomial fitting on the resistance values ​​at multiple frequency points and the inductance values ​​at multiple frequency points to obtain the frequency response fitting result of the resistance and inductance of the transmission line;

[0111] The module 300 is established to establish an impedance model of the transmission line based on the frequency response fitting result of the resistance and inductance of the transmission line.

[0112] Furthermore, in some embodiments, the fitting module 200 is specifically configured to:

[0113] Based on the least squares method, polynomial fitting is performed on the resistance values ​​at multiple frequency points and the inductance values ​​at multiple frequency points, and the initial fitting result and the root mean square error corresponding to the initial fitting result are obtained, and the current fitting order of the polynomial is recorded;

[0114] Based on the initial fitting result, determining whether a root mean square error corresponding to the initial fitting result is less than or equal to a preset error threshold;

[0115] If the root mean square error corresponding to the initial fitting result is less than or equal to the preset error threshold, the initial fitting result is used as the frequency response fitting result of the transmission line impedance inductance; otherwise, the current fitting order is iteratively increased according to the preset rules until the root mean square error corresponding to the new initial fitting result is less than or equal to the preset error threshold.

[0116] Furthermore, in some embodiments, the module 300 is established to:

[0117] Based on the frequency response fitting result of the transmission line impedance and inductance, and according to the preset relationship between the voltage and current at the head end and the end end of the transmission line, a transmission line model considering the frequency correlation of the parameters is obtained;

[0118] Based on the transmission line model considering the frequency correlation of parameters, an impedance model of the transmission line is established according to the terminal state of the transmission line, wherein the terminal state of the transmission line includes the terminal connection impedance of the transmission line, the terminal grounding of the transmission line and the terminal open circuit of the transmission line.

[0119] Furthermore, in some embodiments, when the end of the transmission line is connected to an impedance, the impedance model of the transmission line is:

[0120]

[0121] Among them, Z line is the impedance model of the transmission line, Z g is the impedance of the end connection of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0122] Further, in some embodiments, when the end of the transmission line is grounded, the impedance model of the transmission line is:

[0123]

[0124] Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0125] Furthermore, in some embodiments, when the end of the transmission line is open, the impedance model of the transmission line is:

[0126]

[0127] Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

[0128] It should be noted that the above explanation of the embodiment of the method for frequency-dependent impedance modeling of a power transmission line is also applicable to the device for frequency-dependent impedance modeling of a power transmission line of this embodiment, and will not be repeated here.

[0129] According to the frequency-dependent impedance modeling device of the transmission line proposed in the embodiment of the present application, by obtaining the resistance value of the transmission line at multiple frequency points and the inductance value at multiple frequency points, and performing polynomial fitting on the resistance value at multiple frequency points and the inductance value at multiple frequency points, the impedance model of the transmission line can be established based on the obtained frequency response fitting results of the resistance and inductance of the transmission line. Therefore, by comprehensively considering the distributed parameter characteristics and frequency correlation of the transmission line, a model that can accurately describe the impedance characteristics of the transmission line at different frequencies is constructed, which solves the problem that the prior art has limitations due to only simulating the distributed parameter characteristics of the transmission line and not considering the frequency correlation of the transmission line parameters, improves the accuracy of the transmission line impedance modeling, and provides a theoretical basis for the oscillation stability analysis of the power system.

[0130] Figure 3 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0131] A memory 301 , a processor 302 , and a computer program stored in the memory 301 and executable on the processor 302 .

[0132] When the processor 302 executes the program, the frequency-dependent impedance modeling method provided in the above embodiment is implemented.

[0133] Furthermore, the electronic device further comprises:

[0134] The communication interface 303 is used for communication between the memory 301 and the processor 302 .

[0135] The memory 301 is used to store computer programs that can be run on the processor 302 .

[0136] The memory 301 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0137] If the memory 301, the processor 302 and the communication interface 303 are implemented independently, the communication interface 303, the memory 301 and the processor 302 can be connected to each other through a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 3 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0138] Optionally, in a specific implementation, if the memory 301, the processor 302 and the communication interface 303 are integrated on a chip, the memory 301, the processor 302 and the communication interface 303 can communicate with each other through an internal interface.

[0139] The processor 302 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application.

[0140] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, which implements the above frequency-dependent impedance modeling method when executed by a processor.

[0141] An embodiment of the present application also provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the program implements the above frequency-dependent impedance modeling method.

[0142] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0143] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0144] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for modeling frequency-dependent impedance of a transmission line, characterized in that: The following steps are involved: Obtain the resistance value of the transmission line at multiple frequency points and the inductance value at multiple frequency points; Performing polynomial fitting on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points to obtain a frequency response fitting result of the resistance and inductance of the transmission line; Based on the frequency response fitting result of the resistance and inductance of the transmission line, an impedance model of the transmission line is established.

2. The method according to claim 1, characterized in that The performing polynomial fitting on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points to obtain the frequency response fitting result of the resistance and inductance of the transmission line includes: Based on the least squares method strategy, polynomial fitting is performed on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points respectively, an initial fitting result and a root mean square error corresponding to the initial fitting result are obtained, and a current fitting order of the polynomial is recorded; Based on the initial fitting result, determining whether a root mean square error corresponding to the initial fitting result is less than or equal to a preset error threshold; If the root mean square error corresponding to the initial fitting result is less than or equal to the preset error threshold, the initial fitting result is used as the frequency response fitting result of the transmission line inductance; otherwise, the current fitting order is iteratively increased according to a preset rule until the root mean square error corresponding to the new initial fitting result is less than or equal to the preset error threshold.

3. The method according to claim 1, characterized in that The step of establishing the impedance model of the transmission line based on the frequency response fitting result of the resistance and inductance of the transmission line comprises: Based on the frequency response fitting result of the resistance and inductance of the transmission line, and according to the preset relationship between the voltage and current at the head end and the end end of the transmission line, a transmission line model considering the frequency correlation of parameters is obtained; Based on the transmission line model that takes into account the frequency correlation of parameters, an impedance model of the transmission line is established according to the end state of the transmission line, wherein the end state of the transmission line includes the end connection impedance of the transmission line, the end grounding of the transmission line and the end open circuit of the transmission line.

4. The method according to claim 3, characterized in that When the end of the transmission line is connected to an impedance, the impedance model of the transmission line is: Among them, Z line is the impedance model of the transmission line, Z g is the impedance of the end connection of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

5. The method according to claim 3, characterized in that: When the end of the transmission line is grounded, the impedance model of the transmission line is: Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

6. The method according to claim 3, characterized in that When the end of the transmission line is open, the impedance model of the transmission line is: Among them, Z line is the impedance model of the transmission line, Z(ω) is the impedance of the transmission line per unit length, Y(ω) is the admittance of the transmission line per unit length, and l is the length of the transmission line.

7. A frequency-dependent impedance modeling device for a transmission line, characterized in that: include: An acquisition module, used to acquire resistance values ​​of a transmission line at multiple frequency points and inductance values ​​at multiple frequency points; A fitting module, used to perform polynomial fitting on the resistance values ​​at the multiple frequency points and the inductance values ​​at the multiple frequency points to obtain a frequency response fitting result of the resistance and inductance of the transmission line; An establishing module is used to establish an impedance model of the transmission line based on a frequency response fitting result of the resistance and inductance of the transmission line.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the frequency-dependent impedance modeling method for a power transmission line according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the frequency-dependent impedance modeling method for a transmission line as described in any one of claims 1 to 6.

10. A computer program product, characterized in that It comprises a computer program, which, when executed by a processor, is used to implement the frequency-dependent impedance modeling method of the transmission line according to any one of claims 1 to 6.

Images