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

Abstract

The application 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 following steps: obtaining resistance values of the power transmission line at multiple frequency points and inductance values at the multiple frequency points; performing polynomial fitting on the resistance values at the multiple frequency points and the inductance values at the multiple frequency points; and establishing an impedance model of the power transmission line based on the obtained frequency response fitting result of the resistance and inductance of the power transmission line. Thus, by comprehensively considering the distributed parameter characteristics and frequency dependence of the power transmission line, a model capable of accurately describing the impedance characteristics of the power transmission line at different frequencies is constructed, the problem of the prior art that is limited due to the fact that only the distributed parameter characteristics of the power transmission line are simulated and the frequency dependence of the power transmission line parameters is not considered is solved, the accuracy of the impedance modeling of the power transmission line is improved, and a theoretical basis is provided for power system oscillation stability analysis.

Description

TECHNICAL FIELD

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

[0002] The interaction between the power transmission line in the power system and the grid-connected inverter can cause unstable oscillation risk. Accurate modeling of the power transmission line is of great significance for oscillation analysis and evaluation. The power transmission line not only has a distributed parameter characteristic, but also has a frequency-dependent characteristic of the line resistance and inductance due to the skin effect and proximity effect.

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

[0004] However, the above models can only simulate the distributed parameter characteristic of the power transmission line, and do not consider the frequency dependence of the power transmission line parameters, so there are limitations that need to be solved. SUMMARY

[0005] The present application provides a frequency-dependent impedance modeling method, device, equipment and medium of a power transmission line to solve the problem of limitations in the prior art due to only simulating the distributed parameter characteristic of the power transmission line and not considering the frequency dependence of the power transmission line parameters, thereby improving the accuracy of the impedance modeling of the power transmission line and providing a theoretical basis for power system oscillation stability analysis.

[0006] To achieve the above purpose, the first aspect of the present application provides a frequency-dependent impedance modeling method of a power transmission line, comprising the following steps:

[0007] Obtaining resistance values at a plurality of frequency points and inductance values at a plurality of frequency points of the power transmission line;

[0008] Polynomial fitting is performed on the resistance values at the plurality of frequency points and the inductance values at the plurality of frequency points to obtain a frequency response fitting result of the resistance and inductance of the power transmission line;

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

[0010] According to one embodiment of the present application, the polynomial fitting of the resistance values at the plurality of frequency points and the inductance values at the plurality of frequency points to obtain the frequency response fitting result of the resistance and inductance of the power transmission line comprises:

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

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

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

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

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

[0016] Based on the transmission line model considering parameter frequency correlation, 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 open circuit at the end of the transmission line.

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

[0018]

[0019] wherein, 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 per unit length of the transmission line, Y(ω) is the admittance per unit length of the transmission line, and l is the length of the transmission line.

[0020] According to an embodiment of the present application, when the end grounding of the transmission line is connected, the impedance model of the transmission line is:

[0021]

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

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

[0024]

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

[0026] According to the frequency-dependent impedance modeling method of the power transmission line provided in the embodiments of the present application, by obtaining the resistance values at multiple frequency points and the inductance values at multiple frequency points of the power transmission line, and performing polynomial fitting on the resistance values at multiple frequency points and the inductance values at multiple frequency points, the impedance model of the power transmission line can be established based on the obtained frequency response fitting result of the resistance and inductance of the power transmission line. Thus, by comprehensively considering the distributed parameter characteristics and frequency dependence of the power transmission line, a model capable of accurately describing the impedance characteristics of the power transmission line at different frequencies is constructed, thereby solving the problem of the prior art that has limitations due to only simulating the distributed parameter characteristics of the power transmission line without considering the frequency dependence of the power transmission line parameters, and improving the accuracy of the impedance modeling of the power transmission line, thereby providing a theoretical basis for power system oscillation stability analysis.

[0027] To achieve the above object, the second aspect of the embodiments of the present application provides a frequency-dependent impedance modeling device of a power transmission line, comprising:

[0028] The obtaining module is configured to obtain resistance values at multiple frequency points and inductance values at multiple frequency points of the power transmission line.

[0029] The fitting module is configured to perform polynomial fitting 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 power transmission line.

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

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

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

[0033] Based on the initial fitting result, it is judged whether the 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 taken as the frequency response fitting result of the resistance and inductance of the power transmission line, otherwise, the current fitting order is iteratively increased according to a preset rule until the root mean square error corresponding to a new initial fitting result is less than or equal to the preset error threshold.

[0035] According to an embodiment of the present application, the establishing module is specifically configured to:

[0036] Based on the frequency response fitting result of the resistance and inductance of the power transmission line, a power transmission line model considering parameter frequency correlation is obtained according to a preset relationship between voltages and currents at the head and tail ends of the power transmission line.

[0037] Based on the power transmission line model considering parameter frequency correlation, an impedance model of the power transmission line is established according to a tail end state of the power transmission line, wherein the tail end state of the power transmission line includes a tail end connecting impedance of the power transmission line, a tail end grounding of the power transmission line and a tail end open circuit of the power transmission line.

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

[0039]

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

[0041] According to an embodiment of the present application, when the tail end grounding of the power transmission line, the impedance model of the power transmission line is:

[0042]

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

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

[0045]

[0046] wherein, Z linefor an impedance model of a power transmission line, Z(ω) is an impedance of the power transmission line per unit length, Y(ω) is an admittance of the power transmission line per unit length, and l is a length of the power transmission line.

[0047] The frequency-dependent impedance modeling device for a power transmission line provided by the embodiment of the present application can obtain resistance values at multiple frequency points and inductance values at multiple frequency points of the power transmission line, and perform polynomial fitting on the resistance values at multiple frequency points and the inductance values at multiple frequency points, so as to establish an impedance model of the power transmission line based on the obtained frequency response fitting result of the impedance and inductance of the power transmission line. Thus, by comprehensively considering the distributed parameter characteristics and frequency dependence of the power transmission line, a model capable of accurately describing impedance characteristics of the power transmission line at different frequencies is constructed, the problem of the prior art that is limited due to only simulating the distributed parameter characteristics of the power transmission line and not considering the frequency dependence of the power transmission line parameters is solved, and the accuracy of impedance modeling of the power transmission line is improved, thereby providing a theoretical basis for power system oscillation stability analysis.

[0048] To achieve the above object, the third aspect of 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 the processor executes the program to implement the frequency-dependent impedance modeling method for a power transmission line as described in the above embodiments.

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

[0050] To achieve the above object, the fifth aspect of the present application provides a computer program product comprising a computer program, wherein the computer program is executed by a processor to implement the frequency-dependent impedance modeling method for a power transmission line as described in the above embodiments.

[0051] Additional aspects and advantages of the present application will be made apparent from the following description of embodiments, which proceeds with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

[0056] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which like or similar elements are denoted by the same or similar reference signs throughout the drawings. The embodiments described below are exemplary and are intended to explain the present application, and should not be understood as limiting the present application.

[0057] A method, device, equipment and medium for modeling frequency-dependent impedance of a power transmission line according to an embodiment of the present application are described below with reference to the accompanying drawings.

[0058] Figure 1 A flowchart of a method for modeling frequency-dependent impedance of a power transmission line according to an embodiment of the present application is provided.

[0059] Exemplarily, as shown in Figure 1 the method for modeling frequency-dependent impedance of a power transmission line includes the following steps:

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

[0061] The power transmission line refers to a facility for long-distance transmission of electric energy in a power system, and usually includes high-voltage transmission lines, towers and the like.

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

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

[0064] It can be understood that although increasing the number of frequency points can improve the accuracy of fitting, too many frequency points will also cause a significant increase in 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 measurement and calculation workload can be effectively controlled while ensuring the fitting quality.

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

[0066] However, in some cases, it is not possible to directly obtain the measured data of the power transmission line parameters in actual engineering, and another method (2) can be used. A model of the same type of power transmission line as in the actual engineering is built in the electromagnetic transient simulation software to simulate the actual power transmission line in the software environment, and a series of frequency values f i (where i = 1, 2, …, k) are set, and simulation tests are performed at different frequencies to measure the line resistance and inductance values at these frequencies in the simulation software. Through this method, the resistance and inductance parameter values of the power transmission line at different frequencies can be obtained without actual measurement data.

[0067] In step S102, the resistance values at multiple frequency points and the inductance values at multiple frequency points are polynomial fitted to obtain the frequency response fitting result of the resistance and inductance of the power transmission line.

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

[0069] For ease of understanding, how 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 power transmission line is described in detail below.

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

[0071] It should be noted that in the process of analyzing the transmission line, when considering the influence of the skin effect and the 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 represented as a function of the square root of the frequency. The skin effect refers to the phenomenon that the distribution of alternating current inside a conductor is not uniform, mainly concentrated on the surface of the conductor; the proximity effect refers to the fact that when two or more conductors are close to each other, the distribution of current in these conductors will be affected by each other. Both of these effects will have a significant impact on the resistance and inductance of the transmission line.

[0072] Specifically, based on the least square method strategy, the resistance values R at the plurality of frequency points and the inductance values L at the plurality of frequency points are respectively polynomial fitted, and the fitting expression is as follows:

[0073]

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

[0075] In the process of data fitting, in order to evaluate the accuracy of the initial fitting result, the performance of the fitting model can be evaluated by calculating the root mean square error corresponding to each fitting result (a method for measuring the difference between the predicted value of the model and the actual observed 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, a preset error threshold is set, which is the maximum error range that can be accepted. By calculating the root mean square error corresponding to the current fitting result, it can be judged whether the fitting result meets the accuracy requirement. 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 requirement. Therefore, in order to improve the fitting accuracy of the model, the fitting order of the polynomial can be increased by one, and then the fitting process is performed again. This process is repeated until the accuracy requirement is 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 can be understood that the order of the polynomial determines the complexity of the model. The higher the order, the stronger the fitting ability of the model, but it may also lead to overfitting. Therefore, in actual operation, a balance point between fitting ability and model generalization ability can be found, and a suitable fitting order can be selected. Preferably, the fitting order selected by the embodiments of the present application is 3-4.

[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 met.

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

[0080] That is, by performing detailed fitting analysis on the frequency response of the resistance and inductance of the power transmission line, an accurate impedance model of the power transmission line can be further constructed. The model will be based on actual measurement data, considering the resistance and inductance characteristics of the line, and fitting out its frequency response curve through mathematical methods. In this way, the impedance characteristics of the power transmission line at different frequencies can be more accurately described, thereby providing important reference for the stable operation and fault analysis of the power system.

[0081] Next, how to establish the impedance model of the power transmission line based on the fitting result of the frequency response of the resistance and inductance of the power transmission line will be described in detail.

[0082] As a possible implementation manner, in some embodiments, establishing the impedance model of the power transmission line based on the fitting result of the frequency response of the resistance and inductance of the power transmission line comprises: based on the fitting result of the frequency response of the resistance and inductance of the power transmission line, obtaining a power transmission line model considering frequency correlation of parameters according to a preset relationship between voltages and currents at the first end and the end of the power transmission line; and based on the power transmission line model considering frequency correlation of parameters, establishing the impedance model of the power transmission line according to an end state of the power transmission line, wherein the end state of the power transmission line includes an end connection impedance of the power transmission line, an end grounding of the power transmission line, and an end open circuit of the power transmission line.

[0083] Specifically, by accurately fitting the frequency response of the impedance of the transmission line, the behavior characteristics of the transmission line at different frequencies can be further understood. Based on the fitting results, in combination with the preset relationship between the voltage and the current at the first end and the end of the transmission line, a transmission line model considering the frequency correlation of parameters can be obtained. The preset relationship between the voltage and the current at the first end and the end of the transmission line is as follows:

[0084]

[0085] wherein,

[0086] Z(ω) = R(ω) + jωL(ω); (4)

[0087] Y(ω) = jωC; (5)

[0088] wherein, is the voltage at the first end of the transmission line, is the current at the first end 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 the inductance L(ω) are related to the frequency, Y(ω) is the admittance of the transmission line per unit length, the capacitance C is independent of the frequency, j is the imaginary unit in the complex number, sinh(·) is the hyperbolic sine function, and cosh(·) is the hyperbolic cosine function.

[0089] By substituting equation (1) and equation (2) into equation (3), the transmission line model considering the frequency correlation of parameters can be obtained.

[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 specific state of the end of the transmission line will be described in detail below.

[0091] Alternatively, in some embodiments, when the end of the transmission line is connected with the impedance, the impedance model of the transmission line is:

[0092]

[0093] wherein, Z line is the impedance model of the transmission line, Z g is the impedance connected with the end 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 connected with the end of the transmission line is Zg (impedance characteristic of the device or load connected at the end of the transmission line), then the voltage and current at the end of the transmission line satisfy:

[0095]

[0096] In combination with the transmission line model considering the frequency dependence of parameters and equation (7), the impedance model of the transmission line viewed from the beginning of the line is shown as equation (6).

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

[0098]

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

[0100] That is, when the end of the transmission line is grounded, in combination with the transmission line model considering the frequency dependence of parameters, the impedance model of the transmission line viewed from the beginning of the line is shown as equation (8).

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

[0102]

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

[0104] That is, when the end of the transmission line is open, in combination with the transmission line model considering the frequency dependence of parameters, the impedance model of the transmission line viewed from the beginning of the line is shown as equation (9).

[0105] According to the frequency-dependent impedance modeling method of the power transmission line provided in the embodiments of the present application, the resistance values of the power transmission line at multiple frequency points and the inductance values of the power transmission line at multiple frequency points are obtained, and the resistance values at multiple frequency points and the inductance values at multiple frequency points are polynomially fitted, so that the impedance model of the power transmission line can be established based on the obtained frequency response fitting result of the resistance and inductance of the power transmission line. Thus, by comprehensively considering the distributed parameter characteristics and the frequency dependence of the power transmission line, a model capable of accurately describing the impedance characteristics of the power transmission line at different frequencies is constructed, the problem of the limitation of the prior art due to the simulation of only the distributed parameter characteristics of the power transmission line without considering the frequency dependence of the power transmission line parameters is solved, the accuracy of the impedance modeling of the power transmission line is improved, and a theoretical basis is provided for the power system oscillation stability analysis.

[0106] Secondly, the frequency-dependent impedance modeling device of the power transmission line provided in the embodiments of the present application is described with reference to the accompanying drawings.

[0107] Figure 2 FIG. 1 is a block schematic diagram of the frequency-dependent impedance modeling device of the power transmission line according to an embodiment of the present application.

[0108] As shown in FIG. 1, the frequency-dependent impedance modeling device 10 of the power transmission line includes an obtaining module 100, a fitting module 200 and an establishing module 300. Figure 2 The obtaining module 100 is configured to obtain the resistance values of the power transmission line at multiple frequency points and the inductance values of the power transmission line at multiple frequency points.

[0109] The fitting module 200 is configured to polynomially fit 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 power transmission line.

[0110] The establishing module 300 is configured to establish an impedance model of the power transmission line based on the frequency response fitting result of the resistance and inductance of the power transmission line.

[0111] Further, in some embodiments, the fitting module 200 is specifically configured to:

[0112] based on a least square method strategy, polynomially fit the resistance values at multiple frequency points and the inductance values at multiple frequency points to obtain an initial fitting result and a root mean square error corresponding to the initial fitting result, and record a current fitting order of the polynomial;

[0113] based on the initial fitting result, judge whether the root mean square error corresponding to the initial fitting result is less than or equal to a preset error threshold;

[0114] if the root mean square error corresponding to the initial fitting result is less than or equal to the preset error threshold, the fitting module 200 stops the fitting process; or

[0115] if the root mean square error corresponding to the initial fitting result is greater than the preset error threshold, the fitting module 200 increases the fitting order of the polynomial, and performs the polynomial fitting again.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 taken as the frequency response fitting result of the resistance and inductance of the power 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.

[0116] Further, in some embodiments, the establishing module 300 is specifically used for:

[0117] Based on the frequency response fitting result of the resistance and inductance of the power transmission line, the power transmission line model considering the frequency correlation of parameters is obtained according to the preset relationship between the voltage and the current at the head and the tail of the power transmission line.

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

[0119] Further, in some embodiments, when the end connection impedance of the power transmission line, the impedance model of the power transmission line is:

[0120]

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

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

[0123]

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

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

[0126]

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

[0128] It should be noted that the foregoing explanation of the embodiment of the method for modeling frequency-dependent impedance of a power transmission line also applies to the device for modeling frequency-dependent impedance of a power transmission line of the embodiment, which will not be described here again.

[0129] The device for modeling frequency-dependent impedance of a power transmission line according to the embodiment of the application obtains the resistance values of the power transmission line at multiple frequency points and the inductance values of the power transmission line at multiple frequency points, and performs polynomial fitting on the resistance values at multiple frequency points and the inductance values at multiple frequency points, so as to establish an impedance model of the power transmission line based on the obtained frequency response fitting result of the resistance and inductance of the power transmission line. Thus, by comprehensively considering the distributed parameter characteristics and frequency dependence of the power transmission line, a model capable of accurately describing the impedance characteristics of the power transmission line at different frequencies is constructed, the problem of the prior art that is limited due to only simulating the distributed parameter characteristics of the power transmission line without considering the frequency dependence of the power transmission line parameters is solved, and the accuracy of the impedance modeling of the power transmission line is improved, thereby providing a theoretical basis for the oscillation stability analysis of a power system.

[0130] Figure 3 The electronic device provided in the embodiment of the application has the structure shown in the structural schematic diagram of the electronic device. The electronic device can include:

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

[0132] The processor 302 implements the method for modeling frequency-dependent impedance provided in the above embodiments when executing the program.

[0133] Further, the electronic device further includes:

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

[0135] The memory 301 is used for storing the computer program executable on the processor 302.

[0136] The memory 301 can include a high-speed RAM (Random Access Memory, random access memory) memory and can 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 with each other through a bus and complete communication between 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 the convenience of representation, Figure 3 Only one thick line is used in the figure to represent the bus, but it 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 complete communication between each other through an internal interface.

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

[0140] The embodiment of the present application further provides a computer readable storage medium, which has a computer program stored thereon, and the program is executed by a processor to implement the frequency-dependent impedance modeling method.

[0141] The embodiment of the present application further provides a computer program product, which includes a computer program, and the program is executed by a processor to implement the frequency-dependent impedance modeling method.

[0142] In addition, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited.

[0143] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the 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 is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method of modeling frequency dependent impedance of a power transmission line, characterized by, The method comprises the following steps: obtaining resistance values of a power transmission line at multiple frequency points and inductance values at the 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 power transmission line; establishing an impedance model of the power transmission line based on the frequency response fitting result of the resistance and inductance of the power transmission line; wherein the 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 power transmission line comprises: based on a least square method strategy, performing polynomial fitting on the resistance values at the multiple frequency points and the inductance values at the multiple frequency points respectively to obtain an initial fitting result and a root mean square error corresponding to the initial fitting result, and recording a current fitting order of the polynomial, based on the initial fitting result, judging whether the 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, taking the initial fitting result as the frequency response fitting result of the resistance and inductance of the power transmission line, otherwise, iteratively increasing the current fitting order according to a preset rule until a new initial fitting result corresponding to the root mean square error is less than or equal to the preset error threshold; the establishment of the impedance model of the power transmission line based on the frequency response fitting result of the resistance and inductance of the power transmission line comprises: based on the frequency response fitting result of the resistance and inductance of the power transmission line, obtaining a power transmission line model considering parameter frequency correlation according to a preset relationship between voltages and currents at a first end and a last end of the power transmission line, and based on the power transmission line model considering parameter frequency correlation, establishing the impedance model of the power transmission line according to a last end state of the power transmission line, wherein the last end state of the power transmission line comprises a last end connecting impedance of the power transmission line, a last end grounding of the power transmission line and a last end open circuit of the power transmission line.

2. The method of claim 1, wherein, when the last end connecting impedance of the power transmission line exists, the impedance model of the power transmission line is: wherein, is an impedance model of a power transmission line, is an impedance of a terminal connection of the power transmission line, is an impedance of the power transmission line per unit length, is an admittance of the power transmission line per unit length, is a length of the power transmission line.

3. The method of claim 1, wherein, when the last end grounding of the power transmission line exists, the impedance model of the power transmission line is: wherein, is an impedance model of a power transmission line, is an impedance of the power transmission line per unit length, is an admittance of the power transmission line per unit length, is a length of the power transmission line.

4. The method of claim 1, wherein, when the last end open circuit of the power transmission line exists, the impedance model of the power transmission line is: wherein, is an impedance model of a power transmission line, is an impedance of the power transmission line per unit length, is an admittance of the power transmission line per unit length, is a length of the power transmission line.

5. A device for modeling frequency dependent impedance of a power transmission line, characterized by, comprise: an acquisition module configured to obtain resistance values of a power transmission line at multiple frequency points and inductance values at the multiple frequency points; a fitting module configured 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 power transmission line; an establishment module configured to establish an impedance model of the power transmission line based on the frequency response fitting result of the resistance and inductance of the power transmission line; The fitting module is specifically configured to: based on a least square method strategy, perform polynomial fitting on the resistance values at the plurality of frequency points and the inductance values at the plurality of frequency points respectively, to obtain an initial fitting result and a root mean square error corresponding to the initial fitting result, and record a current fitting order of a polynomial, based on the initial fitting result, determine whether the 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, take the initial fitting result as the frequency response fitting result of the resistance and inductance of the power transmission line, otherwise, iteratively increase the current fitting order according to a preset rule until a new initial fitting result corresponding to the root mean square error is less than or equal to the preset error threshold; The establishing module is specifically configured to: based on the frequency response fitting result of the resistance and inductance of the power transmission line, according to a preset relationship between voltages and currents at a first end and a last end of the power transmission line, obtain a power transmission line model considering parameter frequency correlation, and based on the power transmission line model considering parameter frequency correlation, according to a last end state of the power transmission line, establish an impedance model of the power transmission line, wherein the last end state of the power transmission line includes a last end connecting impedance of the power transmission line, a last end grounding of the power transmission line and a last end open circuit of the power transmission line.

6. An electronic device, comprising: The computer program is executed by the processor to implement the power transmission line frequency-dependent impedance modeling method according to any one of claims 1-4. The program is executed by the processor to implement the power transmission line frequency-dependent impedance modeling method according to any one of claims 1-4.

7. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the power transmission line frequency-dependent impedance modeling method according to any one of claims 1-4.

8. A computer program product, characterised in that, ​

Images