Method, device and equipment for determining transmission impedance of cable and medium

Abstract

The invention discloses a transmission impedance determination method and device of a cable, equipment and a medium, and belongs to the field of power systems, and the method comprises the steps: obtaining a first actual voltage data set and a first actual current data set of the cable, and obtaining a second actual voltage data set and a second actual current data set; according to the second data set, adopting a signal separation method to obtain an estimated voltage data set, a current component data set of each broadband oscillation source and an estimated current data set; a mathematical model is established according to the four-end network model of the cable, the objective function is obtained according to the first actual data set and the estimated data set, and the constraint condition is obtained according to the four-end network model; solving the mathematical model through a preset solving algorithm to obtain a parameter set, and further determining the transmission impedance of the cable. Therefore, by implementing the method and the device, the problem that the transmission impedance of the cable is difficult to accurately determine while the broadband oscillation influence is considered in the prior art can be solved.

Description

Technical Field

[0001] The present invention relates to the field of power systems, and in particular to a method and device for determining the transmission impedance of a cable, equipment, and a medium. Background Art

[0002] In modern power systems, cables are core transmission components, and determining their transmission impedance is fundamental to system power flow calculations, fault analysis, and stability control. With the large-scale integration of nonlinear devices such as renewable energy grid-connected equipment and industrial frequency converters, broadband oscillations are becoming more frequent in power systems, significantly altering the transmission impedance of cables.

[0003] In the prior art, traditional methods for determining cable transmission impedance typically directly employ simplified circuit models at the fundamental frequency, without considering the influence of broadband oscillation sources. Furthermore, due to the lack of an effective signal separation mechanism, prior art also struggles to extract the independent current components of each broadband oscillation source from the mixed signal, resulting in a mismatch between the cable equivalent model and the actual operating conditions. Furthermore, prior art does not establish a mathematical model containing constraints based on the multi-port network characteristics of the cable, but rather solves the impedance parameters through simple algebraic operations. Therefore, there is an urgent need for a method that can accurately determine the transmission impedance of a cable while taking into account the influence of broadband oscillations. Summary of the Invention

[0004] The present invention provides a method and apparatus, a device and a medium for determining the transmission impedance of a cable, which can solve the problem in the prior art that it is difficult to accurately determine the transmission impedance of a cable while taking into account the influence of broadband oscillation.

[0005] In a first aspect, an embodiment of the present invention provides a method for determining the transmission impedance of a cable, comprising:

[0006] Acquire a first actual voltage data set and a first actual current data set of the cable, and obtain a second actual voltage data set and a second actual current data set based on the first actual voltage data set and the first actual current data set; wherein the cable includes a plurality of broadband oscillation sources;

[0007] Using a signal separation method to obtain an estimated voltage dataset and a current component dataset of each broadband oscillation source based on the second actual voltage dataset and the second actual current dataset, and obtaining an estimated current dataset based on the current component dataset of each broadband oscillation source;

[0008] Establishing a mathematical model based on the four-terminal network model of the cable; wherein the objective function of the mathematical model is obtained based on the first actual voltage data set, the first actual current data set, the estimated voltage data set, and the estimated current data set; and the constraints of the mathematical model are obtained based on the four-terminal network model of the cable;

[0009] The mathematical model is solved by a preset solving algorithm to obtain a parameter set, and the transmission impedance of the cable is determined according to the parameter set.

[0010] The embodiment of the present application obtains a first actual voltage dataset and a first actual current dataset of the cable and obtains a second actual voltage dataset and a second actual current dataset based on the first actual voltage dataset and the first actual current dataset. Then, based on the preprocessed second actual voltage dataset and current dataset, a signal separation method is used to accurately separate the independent current components of each broadband oscillation source and the corresponding estimated voltage and current datasets from a mixed signal containing multiple broadband oscillation sources. This process breaks through the limitation of traditional methods that only consider the fundamental frequency and further considers the impact of each broadband oscillation source in a complex environment, providing initial estimated data for mathematical modeling. Then, when establishing a mathematical model based on the four-terminal network model of the cable, the present application constructs an objective function based on the error between the actual measured data and the estimated data to ensure that the model output can closely match the actual operating state of the cable; at the same time, constraints based on the characteristics of the multi-port network are introduced to limit the model parameters to conform to the physical characteristics of the cable. Finally, the mathematical model is iteratively optimized and solved using a preset solution algorithm to obtain a parameter set including parameters such as longitudinal resistance, reactance, and parallel conductance, and the transmission impedance of the cable is then determined based on this parameter set. Therefore, through the above technical means, the transmission impedance of the cable can be accurately determined while taking into account the influence of broadband oscillation.

[0011] As a preferred example of the first aspect, the estimated voltage dataset and the current component datasets of each broadband oscillation source are obtained by using a signal separation method based on the second actual voltage dataset and the second actual current dataset, specifically:

[0012] Processing the second actual voltage data set and the second actual current data set using a mixed signal construction method to obtain a mixed signal data set;

[0013] A signal separation method is used to separate the mixed signal data set into an estimated voltage data set and a current component data set of each broadband oscillation source.

[0014] In this preferred example, the preprocessed voltage and current data sets are processed by a mixed signal construction method, and the preprocessed voltage and current data sets can be processed into a mixed signal to facilitate unified analysis; the signal separation method is used to decouple the estimated voltage and the current components of each broadband oscillation source, thereby achieving precise separation of each broadband oscillation source in the mixed signal, and providing accurate initial estimation data for the cable transmission impedance calculation.

[0015] As a preferred example of the first aspect, the objective function of the mathematical model is obtained based on the first actual voltage dataset, the first actual current dataset, the estimated voltage dataset, and the estimated current dataset, and is specifically:

[0016] The objective function of the mathematical model is expressed as follows:

[0017]

[0018] Among them, V r,j is the real part of the jth actual voltage in the first actual voltage data set, V m,j is the imaginary part of the jth actual voltage in the first actual voltage data set, I r,j is the real part of the jth actual current in the first actual current data set, I m,j is the imaginary part of the jth actual current in the first actual current data set, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set.

[0019] In this preferred example, by taking the sum of the squares of the real and imaginary errors of the first actual voltage and current data set and the estimated voltage and current data set as the objective function of the mathematical model, the overall deviation between the measured data and the estimated data can be minimized, forcing the model parameters to be optimized in the direction of truly reflecting the broadband oscillation characteristics of the cable, thereby ensuring that the constructed multi-port network model can be highly consistent with the actual electrical behavior of the cable, providing a reliable optimization target for the subsequent solution of the multi-port network parameters, and thereby improving the accuracy of the cable transmission impedance results.

[0020] As a preferred example of the first aspect, the constraints of the mathematical model are obtained based on the multi-port network of the cable, specifically:

[0021] The constraint conditions of the mathematical model are expressed as follows:

[0022]

[0023] in, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set, and a′, a″, b′, b″, c′, c″, d′ and d″ are parameters of the multi-port network of the cable.

[0024] In this preferred example, by using the cable's multi-port network parameter relationships as constraints in the mathematical model, the electrical logical relationship between the estimated voltage and current data and the multi-port network parameters is enforced, ensuring that the parameters solved by the model strictly adhere to the physical structural characteristics of the cable. This constraint mechanism effectively avoids invalid solutions that deviate from practical physical meaning, ensuring that the mathematical model is always optimized within the feasible domain that conforms to the cable's electrical principles, and ultimately ensuring that the resulting transmission impedance results are closer to the actual value.

[0025] As a preferred example of the first aspect, determining the transmission impedance of the cable according to the parameter set is specifically:

[0026] Obtaining longitudinal resistance, reactance, parallel conductance, and parallel susceptance through conversion formulas according to the parameter set;

[0027] Obtaining a series impedance according to the longitudinal resistance and the reactance, and obtaining a parallel admittance according to the parallel conductance and the parallel susceptance;

[0028] A final transmission impedance of the cable is determined according to the series impedance and the shunt admittance.

[0029] In this preferred example, specific electrical parameters such as longitudinal resistance and reactance are obtained through parameter set conversion, and the abstract model is converted into an intuitive physical description; then the transmission impedance is determined by series impedance and parallel admittance, which can accurately determine the transmission impedance of the cable while taking into account the influence of broadband oscillations.

[0030] In a second aspect, the present invention provides a device for determining transmission impedance of a cable, comprising: a data acquisition module, a data processing module, a model building module, and an impedance determination module;

[0031] The data acquisition module is configured to acquire a first actual voltage data set and a first actual current data set of the cable, and obtain a second actual voltage data set and a second actual current data set based on the first actual voltage data set and the first actual current data set; wherein the cable includes a plurality of broadband oscillation sources;

[0032] The data processing module is configured to obtain an estimated voltage dataset and current component datasets of each broadband oscillation source using a signal separation method based on the second actual voltage dataset and the second actual current dataset, and obtain an estimated current dataset based on the current component datasets of each broadband oscillation source;

[0033] The model building module is configured to build a mathematical model based on the four-terminal network model of the cable; wherein the objective function of the mathematical model is obtained based on the first actual voltage data set, the first actual current data set, the estimated voltage data set, and the estimated current data set; and the constraints of the mathematical model are obtained based on the four-terminal network model of the cable;

[0034] The impedance determination module is configured to solve the mathematical model using a preset solution algorithm to obtain a parameter set, and determine the transmission impedance of the cable according to the parameter set.

[0035] As a preferred example of the second aspect, the data processing module includes a first processing unit and a second processing unit;

[0036] The first processing unit is configured to process the second actual voltage data set and the second actual current data set using a mixed signal construction method to obtain a mixed signal data set;

[0037] The second processing unit is configured to separate the mixed signal data set into an estimated voltage data set and a current component data set of each broadband oscillation source by using a signal separation method.

[0038] As a preferred example of the second aspect, the objective function of the mathematical model is obtained based on the first actual voltage dataset, the first actual current dataset, the estimated voltage dataset, and the estimated current dataset, and is specifically:

[0039] The objective function of the mathematical model is expressed as follows:

[0040]

[0041] Among them, V r,j is the real part of the jth actual voltage in the first actual voltage data set, V m,j is the imaginary part of the jth actual voltage in the first actual voltage data set, I r,j is the real part of the jth actual current in the first actual current data set, I m,j is the imaginary part of the jth actual current in the first actual current data set, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set.

[0042] As a preferred example of the second aspect, the constraints of the mathematical model are obtained based on the multi-port network of the cable, specifically:

[0043] The constraint conditions of the mathematical model are expressed as follows:

[0044]

[0045] in, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set, and a′, a″, b′, b″, c′, c″, d′ and d″ are parameters of the multi-port network of the cable.

[0046] As a preferred example of the second aspect, the impedance determination module includes a first determination unit, a second determination unit, and a third determination unit;

[0047] The first determining unit is configured to obtain longitudinal resistance, reactance, parallel conductance, and parallel susceptance through a conversion formula according to the parameter set;

[0048] The second determining unit is configured to obtain a series impedance according to the longitudinal resistance and the reactance, and to obtain a parallel admittance according to the parallel conductance and the parallel susceptance;

[0049] The third determining unit is configured to determine a final transmission impedance of the cable according to the series impedance and the parallel admittance.

[0050] In summary, the embodiment of the present application obtains a first actual voltage dataset and a first actual current dataset of the cable and obtains a second actual voltage dataset and a second actual current dataset based on the first actual voltage dataset and the first actual current dataset. Then, based on the preprocessed second actual voltage dataset and current dataset, a signal separation method is used to accurately separate the independent current components of each broadband oscillation source and the corresponding estimated voltage and current datasets from a mixed signal containing multi-source broadband oscillations. This process breaks through the limitation of traditional methods that only consider the fundamental frequency, further considers the impact of each broadband oscillation source in a complex environment, and provides initial estimated data for mathematical modeling. Then, when establishing a mathematical model based on the four-terminal network model of the cable, the present application constructs an objective function based on the error between the actual measured data and the estimated data to ensure that the model output can closely match the actual operating state of the cable; at the same time, constraints based on the characteristics of the multi-port network are introduced to limit the model parameters to conform to the physical characteristics of the cable. Finally, the mathematical model is iteratively optimized and solved using a preset solution algorithm to obtain a parameter set including parameters such as longitudinal resistance, reactance, and parallel conductance, and then the transmission impedance of the cable is determined based on this parameter set. Therefore, through the above technical means, the transmission impedance of the cable can be accurately determined while taking into account the influence of broadband oscillation.

[0051] Another embodiment of the present invention further provides a terminal device, comprising: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the steps of the method for determining the transmission impedance of the cable of the present invention are implemented.

[0052] Another embodiment of the present invention further provides a computer-readable storage medium item, comprising: a stored computer program, which controls the device where the computer-readable storage medium is located to execute the steps of the method for determining the transmission impedance of the cable of the present invention when the computer program is executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0054] Figure 1 A schematic flow chart of an embodiment of a method for determining the transmission impedance of a cable provided by the present invention;

[0055] Figure 2 A schematic diagram of the equivalent reactance of a cable according to an embodiment of a method for determining the transmission impedance of a cable provided by the present invention;

[0056] Figure 3 A simplified equivalent circuit diagram of a cable according to an embodiment of a method for determining transmission impedance of a cable provided by the present invention;

[0057] Figure 4 This is a module structure diagram of an embodiment of a device for determining the transmission impedance of a cable provided by the present invention. DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0060] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0061] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0062] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0063] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0064] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0065] Example 1

[0066] See also Figure 1 To address the problem in the prior art of difficulty in accurately determining the transmission impedance of a cable while taking into account the influence of broadband oscillation, an embodiment of the present invention provides a method for determining the transmission impedance of a cable, comprising:

[0067] S1. Obtain a first actual voltage dataset and a first actual current dataset of the cable, and obtain a second actual voltage dataset and a second actual current dataset based on the first actual voltage dataset and the first actual current dataset; wherein the cable includes a plurality of broadband oscillation sources;

[0068] Specifically, acquiring the first actual voltage dataset and the first actual current dataset of the cable, and obtaining the second actual voltage dataset and the second actual current dataset based on the first actual voltage dataset and the first actual current dataset can be implemented in the following manner:

[0069] The voltage and current phasor data are collected in real time by a data acquisition card and high-precision voltage probes and current probes installed at both ends of the cable, and then the collected first actual voltage data set and the first actual current data set are transmitted to the data preprocessing module. In the data preprocessing module, the collected first actual current data set and the first actual current data set are denoised and normalized to obtain the second actual voltage data set and the second actual current data set. The denoising process mentioned above can use methods such as low-pass filters or wavelet transforms to remove high-frequency noise components and retain the main features of the signal. The data is smoothed by the moving average method to reduce the impact of random errors and improve the stability of the data. Normalization processing can process the data through the normalization formula, and the normalization formula is:

[0070]

[0071] Among them, x i is the original data, For the normalized data, min(x) and max(x) are the minimum and maximum values ​​of the data respectively.

[0072] S2. Using a signal separation method to obtain an estimated voltage dataset and current component datasets of each broadband oscillation source based on the second actual voltage dataset and the second actual current dataset, and obtaining an estimated current dataset based on the current component datasets of each broadband oscillation source;

[0073] Specifically, in order to fully explain the above steps, the following scheme is used as an example for illustration: Further, in some embodiments of the present application, the estimated voltage dataset and the current component dataset of each broadband oscillation source are obtained by using a signal separation method based on the second actual voltage dataset and the second actual current dataset, specifically:

[0074] Processing the second actual voltage data set and the second actual current data set using a mixed signal construction method to obtain a mixed signal data set;

[0075] A signal separation method is used to separate the mixed signal data set into an estimated voltage data set and a current component data set of each broadband oscillation source.

[0076] Specifically, in order to fully explain the above steps, the following scheme is used as an example:

[0077] First, establish a mixed signal model: Assuming that there are multiple broadband oscillator sources in the cable system, the measured voltage and current phasor data can be expressed as a mixed signal of the broadband oscillator source and the cable impedance. The mixed signal model can be expressed as:

[0078] x(t)=As(t)+n(t)

[0079] Where x(t) is the observed voltage and current phasor data, A is the mixing matrix, s(t) is the current component of each broadband oscillator source, and n(t) is the noise.

[0080] Then, the independent component analysis algorithm is applied to decompose the mixed signal into independent source signals by maximizing the non-Gaussianity of the signal, which includes the following process:

[0081] (1) Data preprocessing

[0082] ①Centralized processing

[0083] The collected current data is centered so that the mean of the data is zero. The specific formula is as follows:

[0084] Icentered =I-μ

[0085]

[0086] Where I is the collected current data matrix, each column represents the current measurement value at a time point, μ is the mean vector of the current data, T is the number of time points, I centered is the current data matrix after centralization.

[0087] ② Whiten the centralized current data to eliminate the correlation in the data. Whitening can be achieved through singular value decomposition (SVD).

[0088] I white =WI centered

[0089] Among them, W is the whitening matrix, which is obtained by singular value decomposition (SVD), I white is the whitened matrix.

[0090] (2) Initialize the separation matrix A -1 Through iterative optimization algorithm, the separation matrix A is gradually adjusted -1 , so as to maximize the non-Gaussianity of the separated signal. Commonly used non-Gaussianity measurement methods include negative entropy and kurtosis.

[0091] (3) Estimation of the current component of the broadband oscillation source

[0092] After iterative optimization, the separation matrix A is obtained -1 It can be used to estimate the current components of each broadband oscillator source:

[0093] I source =A -1 I white

[0094] Among them, I source is the current component matrix of the separated broadband oscillator source, each column represents a current component of the broadband oscillator source; A -1 is the optimized separation matrix; I white is the whitened current data matrix.

[0095] like Figure 2 As shown, the frequency characteristics of the separated current components of each broadband oscillator source are further analyzed. The current component of each broadband oscillator source can be expressed as:

[0096]

[0097] Among them, I source,i (t) is the current component of the i-th broadband oscillator source, I measured,m(t) is the current phasor at the mth measurement point, a im is an element of the mixing matrix, which represents the contribution of the i-th broadband oscillator source to the m-th measurement point.

[0098] like Figure 3 As shown in Figure 1, the equivalent impedance of the cable is estimated based on the separated broadband oscillation source current component and the measured voltage phasor data. The equivalent impedance can be expressed as:

[0099]

[0100] Among them, Z Estimated is the equivalent impedance, V measured (t) is the measured voltage phasor, I source,i (t) is the current component of the i-th broadband oscillator source, and N is the number of broadband oscillators.

[0101] S3. Establishing a mathematical model based on the four-terminal network model of the cable; wherein the objective function of the mathematical model is obtained based on the first actual voltage data set, the first actual current data set, the estimated voltage data set, and the estimated current data set; and the constraints of the mathematical model are obtained based on the four-terminal network model of the cable;

[0102] Furthermore, in some embodiments of the present application, the objective function of the mathematical model is obtained based on the first actual voltage dataset, the first actual current dataset, the estimated voltage dataset, and the estimated current dataset, and is specifically:

[0103] The objective function of the mathematical model is expressed as follows:

[0104]

[0105] Among them, V r,j is the real part of the jth actual voltage in the first actual voltage data set, V m,j is the imaginary part of the jth actual voltage in the first actual voltage data set, I r,j is the real part of the jth actual current in the first actual current data set, I m,j is the imaginary part of the jth actual current in the first actual current data set, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set.

[0106] Furthermore, in some embodiments of the present application, the constraints of the mathematical model are obtained based on the multi-port network of the cable, specifically:

[0107] The constraint conditions of the mathematical model are expressed as follows:

[0108]

[0109] in, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set, and a′, a″, b′, b″, c′, c″, d′ and d″ are parameters of the multi-port network of the cable.

[0110] S4. Solve the mathematical model using a preset solution algorithm to obtain a parameter set, and determine the transmission impedance of the cable according to the parameter set.

[0111] Furthermore, in some embodiments of the present application, determining the transmission impedance of the cable according to the parameter set is specifically:

[0112] Obtaining longitudinal resistance, reactance, parallel conductance, and parallel susceptance through conversion formulas according to the parameter set;

[0113] Obtaining a series impedance according to the longitudinal resistance and the reactance, and obtaining a parallel admittance according to the parallel conductance and the parallel susceptance;

[0114] A final transmission impedance of the cable is determined according to the series impedance and the shunt admittance.

[0115] Specifically, in order to fully explain the above steps, the following scheme is used as an example:

[0116] The optimization problem is solved using an iterative optimization algorithm to obtain a parameter set, which includes a′, a″, b′, b″, c′, c″, d′, and d″. Among them, b is the voltage-current relationship parameter of the four-terminal network, which indicates the magnitude of the voltage at the transmitting end when the current at the receiving end is 1; d is the current-current relationship parameter of the four-terminal network, which indicates the magnitude of the current at the transmitting end when the current at the receiving end is 1. It can be converted to the Norton impedance Z in the equivalent model by the following formula Norton :

[0117] Z Norton =(b′+b″) / (d′+d″)

[0118] Among them, ZNorton The real part represents the longitudinal resistance, Z Norton The imaginary part represents reactance.

[0119] a is the voltage-current relationship parameter of the four-terminal network, which indicates the magnitude of the current at the sending end when the voltage at the receiving end is 1; c is the current-current relationship parameter of the four-terminal network, which indicates the magnitude of the current at the sending end when the current at the receiving end is 1. It can be converted into the parallel admittance Y using the following formula:

[0120] Y = (c′ + c″) / (a′ + a″)

[0121] Here, the real part Y represents the parallel conductance, and the imaginary part Y represents the parallel susceptance.

[0122] In the above steps, we get the longitudinal resistance, reactance, parallel conductance and parallel susceptance. These parameters are important parameters for describing the transmission characteristics of the cable and can be used to calculate the transmission impedance of the cable. The transmission impedance Z of the cable can be expressed as:

[0123] Z=R+jX

[0124] Where R is the longitudinal resistance, X is the reactance, and j is the imaginary unit.

[0125] The parallel admittance Y is usually used to describe the admittance part of the cable parallel branch. It reflects the current shunting effect of the cable and can be expressed as:

[0126] Y=G+jB

[0127] Where G is the parallel conductance and B is the parallel susceptance.

[0128] In practical applications, the transmission impedance of a cable not only includes the series impedance but may also be affected by the parallel admittance. Therefore, considering both series and parallel parameters, the transmission impedance of a cable can be expressed as:

[0129]

[0130] Among them, Z total is the final transmission impedance of the cable, Z is the transmission impedance of the cable, and Y is the shunt admittance.

[0131] In summary, the embodiment of the present application obtains a first actual voltage dataset and a first actual current dataset of the cable and obtains a second actual voltage dataset and a second actual current dataset based on the first actual voltage dataset and the first actual current dataset. Then, based on the preprocessed second actual voltage dataset and current dataset, a signal separation method is used to accurately separate the independent current components of each broadband oscillation source and the corresponding estimated voltage and current datasets from a mixed signal containing multi-source broadband oscillations. This process breaks through the limitation of traditional methods that only consider the fundamental frequency, further considers the impact of each broadband oscillation source in a complex environment, and provides initial estimated data for mathematical modeling. Then, when establishing a mathematical model based on the four-terminal network model of the cable, the present application constructs an objective function based on the error between the actual measured data and the estimated data to ensure that the model output can closely match the actual operating state of the cable; at the same time, constraints based on the characteristics of the multi-port network are introduced to limit the model parameters to conform to the physical characteristics of the cable. Finally, the mathematical model is iteratively optimized and solved using a preset solution algorithm to obtain a parameter set including parameters such as longitudinal resistance, reactance, and parallel conductance, and then the transmission impedance of the cable is determined based on this parameter set. Therefore, through the above technical means, the transmission impedance of the cable can be accurately determined while taking into account the influence of broadband oscillation.

[0132] Example 2

[0133] like Figure 4 As shown, based on the above method embodiment, a corresponding device embodiment is provided;

[0134] An embodiment of the present invention provides a device for determining transmission impedance of a cable, comprising: a data acquisition module 41, a data processing module 42, a model building module 43, and an impedance determination module 44;

[0135] Furthermore, in some embodiments of the present application, the data acquisition module 41 is used to acquire a first actual voltage data set and a first actual current data set of the cable, and obtain a second actual voltage data set and a second actual current data set based on the first actual voltage data set and the first actual current data set; wherein, the cable includes several broadband oscillation sources; the data processing module 42 is used to obtain an estimated voltage data set and a current component data set of each broadband oscillation source based on the second actual voltage data set and the second actual current data set using a signal separation method, and obtain an estimated current data set based on the current component data set of each broadband oscillation source; the model establishment module 43 is used to establish a mathematical model based on the four-terminal network model of the cable; wherein, the objective function of the mathematical model is obtained based on the first actual voltage data set, the first actual current data set, the estimated voltage data set and the estimated current data set; the constraint conditions of the mathematical model are obtained based on the four-terminal network model of the cable; the impedance determination module 44 is used to solve the mathematical model through a preset solution algorithm, obtain a parameter set, and determine the transmission impedance of the cable based on the parameter set.

[0136] Furthermore, in some embodiments of the present application, the data processing module 42 includes a first processing unit and a second processing unit; the first processing unit is used to process the second actual voltage data set and the second actual current data set using a mixed signal construction method to obtain a mixed signal data set; the second processing unit is used to separate the mixed signal data set into an estimated voltage data set and a current component data set of each wide-band oscillation source using a signal separation method.

[0137] Furthermore, in some embodiments of the present application, the objective function of the mathematical model is obtained based on the first actual voltage dataset, the first actual current dataset, the estimated voltage dataset, and the estimated current dataset, and is specifically:

[0138] The objective function of the mathematical model is expressed as follows:

[0139]

[0140] Among them, V r,j is the real part of the jth actual voltage in the first actual voltage data set, V m,j is the imaginary part of the jth actual voltage in the first actual voltage data set, I r,j is the real part of the jth actual current in the first actual current data set, I m,j is the imaginary part of the jth actual current in the first actual current data set, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set.

[0141] Furthermore, in some embodiments of the present application, the constraints of the mathematical model are obtained based on the multi-port network of the cable, specifically:

[0142] The constraint conditions of the mathematical model are expressed as follows:

[0143]

[0144] in, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set, and a′, a″, b′, b″, c′, c″, d′ and d″ are parameters of the multi-port network of the cable.

[0145] Furthermore, in some embodiments of the present application, the impedance determination module 44 includes a first determination unit, a second determination unit, and a third determination unit; the first determination unit is used to obtain the longitudinal resistance, reactance, parallel conductance, and parallel susceptance through a conversion formula based on the parameter set; the second determination unit is used to obtain the series impedance based on the longitudinal resistance and the reactance, and to obtain the parallel admittance based on the parallel conductance and the parallel susceptance; the third determination unit is used to determine the final transmission impedance of the cable based on the series impedance and the parallel admittance.

[0146] For more detailed steps and working principles of this embodiment, please refer to, but not limited to, the relevant records of Embodiment 1.

[0147] In summary, the embodiment of the present application obtains a first actual voltage dataset and a first actual current dataset of the cable and obtains a second actual voltage dataset and a second actual current dataset based on the first actual voltage dataset and the first actual current dataset. Then, based on the preprocessed second actual voltage dataset and current dataset, a signal separation method is used to accurately separate the independent current components of each broadband oscillation source and the corresponding estimated voltage and current datasets from a mixed signal containing multi-source broadband oscillations. This process breaks through the limitation of traditional methods that only consider the fundamental frequency, further considers the impact of each broadband oscillation source in a complex environment, and provides initial estimated data for mathematical modeling. Then, when establishing a mathematical model based on the four-terminal network model of the cable, the present application constructs an objective function based on the error between the actual measured data and the estimated data to ensure that the model output can closely match the actual operating state of the cable; at the same time, constraints based on the characteristics of the multi-port network are introduced to limit the model parameters to conform to the physical characteristics of the cable. Finally, the mathematical model is iteratively optimized and solved using a preset solution algorithm to obtain a parameter set including parameters such as longitudinal resistance, reactance, and parallel conductance, and then the transmission impedance of the cable is determined based on this parameter set. Therefore, through the above technical means, the transmission impedance of the cable can be accurately determined while taking into account the influence of broadband oscillation.

[0148] It can be understood that the above-mentioned device embodiment corresponds to the method embodiment of the present invention, and can implement the method for determining the transmission impedance of the cable provided by any of the above-mentioned method embodiments of the present invention.

[0149] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. Furthermore, in the drawings of the device embodiments provided by the present invention, the connection relationship between modules indicates that they have a communication connection, which may be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement the present invention without inventive effort.

[0150] Example 3

[0151] Based on the above-mentioned embodiment of the method for determining the transmission impedance of a cable, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the method for determining the transmission impedance of a cable according to any embodiment of the present invention is implemented.

[0152] For example, in this embodiment, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to implement the present invention. The one or more module elements may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in the terminal device.

[0153] The terminal device may be a computing device such as a desktop computer, a notebook computer, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0154] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the terminal device, connecting various parts of the entire terminal device using various interfaces and lines.

[0155] Example 4

[0156] Based on the above method embodiments, another embodiment of the present invention provides a computer-readable storage medium, including a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the method for determining the transmission impedance of the cable described in any one of the above method embodiments of the present invention.

[0157] Wherein, the module / unit integrated in the device / terminal equipment, if implemented in the form of a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by the processor, it can implement the steps of the above-mentioned various method embodiments. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0158] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for determining the transmission impedance of a cable, characterized in that: include: Acquire a first actual voltage data set and a first actual current data set of the cable, and obtain a second actual voltage data set and a second actual current data set based on the first actual voltage data set and the first actual current data set; wherein the cable includes a plurality of broadband oscillation sources; Using a signal separation method to obtain an estimated voltage dataset and current component datasets of each broadband oscillation source based on the second actual voltage dataset and the second actual current dataset, and obtaining an estimated current dataset based on the current component datasets of each broadband oscillation source; Establishing a mathematical model based on the four-terminal network model of the cable; wherein the objective function of the mathematical model is obtained based on the first actual voltage data set, the first actual current data set, the estimated voltage data set, and the estimated current data set; and the constraints of the mathematical model are obtained based on the four-terminal network model of the cable; The mathematical model is solved by a preset solving algorithm to obtain a parameter set, and the transmission impedance of the cable is determined according to the parameter set.

2. The method for determining the transmission impedance of a cable according to claim 1, wherein: The method of using a signal separation method to obtain an estimated voltage dataset and a current component dataset of each broadband oscillation source according to the second actual voltage dataset and the second actual current dataset is specifically as follows: Processing the second actual voltage data set and the second actual current data set using a mixed signal construction method to obtain a mixed signal data set; A signal separation method is used to separate the mixed signal data set into an estimated voltage data set and a current component data set of each broadband oscillation source.

3. The method for determining the transmission impedance of a cable according to claim 1, wherein: The objective function of the mathematical model is obtained according to the first actual voltage data set, the first actual current data set, the estimated voltage data set, and the estimated current data set, and is specifically: The objective function of the mathematical model is expressed as follows: Among them, V r,j is the real part of the jth actual voltage in the first actual voltage data set, V m,j is the imaginary part of the jth actual voltage in the first actual voltage data set, I r,j is the real part of the jth actual current in the first actual current data set, I m,j is the imaginary part of the jth actual current in the first actual current data set, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set.

4. The method for determining the transmission impedance of a cable according to claim 1, wherein: The constraints of the mathematical model are obtained based on the multi-port network of the cable, specifically: The constraint conditions of the mathematical model are expressed as follows: in, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set, and a′, a″, b′, b″, c′, c″, d′ and d″ are parameters of the multi-port network of the cable.

5. The method for determining the transmission impedance of a cable according to claim 1, wherein: The determining of the transmission impedance of the cable according to the parameter set is specifically: Obtaining longitudinal resistance, reactance, parallel conductance, and parallel susceptance through conversion formulas according to the parameter set; Obtaining a series impedance according to the longitudinal resistance and the reactance, and obtaining a parallel admittance according to the parallel conductance and the parallel susceptance; A final transmission impedance of the cable is determined according to the series impedance and the shunt admittance.

6. A device for determining the transmission impedance of a cable, characterized in that: include: Data acquisition module, data processing module, model building module and impedance determination module; The data acquisition module is configured to acquire a first actual voltage data set and a first actual current data set of the cable, and obtain a second actual voltage data set and a second actual current data set based on the first actual voltage data set and the first actual current data set; wherein the cable includes a plurality of broadband oscillation sources; The data processing module is configured to obtain an estimated voltage dataset and current component datasets of each broadband oscillation source using a signal separation method based on the second actual voltage dataset and the second actual current dataset, and obtain an estimated current dataset based on the current component datasets of each broadband oscillation source; The model building module is configured to build a mathematical model based on the four-terminal network model of the cable; wherein the objective function of the mathematical model is obtained based on the first actual voltage data set, the first actual current data set, the estimated voltage data set, and the estimated current data set; and the constraints of the mathematical model are obtained based on the four-terminal network model of the cable; The impedance determination module is configured to solve the mathematical model using a preset solution algorithm to obtain a parameter set, and determine the transmission impedance of the cable according to the parameter set.

7. The device for determining transmission impedance of a cable according to claim 6, wherein: The data processing module includes a first processing unit and a second processing unit; The first processing unit is configured to process the second actual voltage data set and the second actual current data set using a mixed signal construction method to obtain a mixed signal data set; The second processing unit is configured to separate the mixed signal data set into an estimated voltage data set and a current component data set of each broadband oscillation source by using a signal separation method.

8. The device for determining transmission impedance of a cable according to claim 6, wherein: The objective function of the mathematical model is obtained according to the first actual voltage data set, the first actual current data set, the estimated voltage data set, and the estimated current data set, and is specifically: The objective function of the mathematical model is expressed as follows: Among them, V r,j is the real part of the jth actual voltage in the first actual voltage data set, V m,j is the imaginary part of the jth actual voltage in the first actual voltage data set, I r,j is the real part of the jth actual current in the first actual current data set, I m,j is the imaginary part of the jth actual current in the first actual current data set, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set.

9. The device for determining transmission impedance of a cable according to claim 6, wherein: The constraints of the mathematical model are obtained based on the multi-port network of the cable, specifically: The constraint conditions of the mathematical model are expressed as follows: in, is the real part of the j-th estimated voltage in the estimated voltage data set, is the imaginary part of the j-th estimated voltage in the estimated voltage data set, is the real part of the j-th estimated current in the estimated current data set, is the imaginary part of the j-th estimated current in the estimated current data set, and a′, a″, b′, b″, c′, c″, d′ and d″ are parameters of the multi-port network of the cable.

10. The device for determining transmission impedance of a cable according to claim 6, wherein: The impedance determination module includes a first determination unit, a second determination unit and a third determination unit; The first determining unit is configured to obtain longitudinal resistance, reactance, parallel conductance, and parallel susceptance through a conversion formula according to the parameter set; The second determining unit is configured to obtain a series impedance according to the longitudinal resistance and the reactance, and to obtain a parallel admittance according to the parallel conductance and the parallel susceptance; The third determining unit is configured to determine a final transmission impedance of the cable according to the series impedance and the parallel admittance.

11. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, the method for determining the transmission impedance of the cable according to any one of claims 1 to 5 is implemented.

12. A computer-readable storage medium, characterized in that include: A stored computer program, wherein when the computer program is run, the device where the computer-readable storage medium is located is controlled to execute the method for determining the transmission impedance of a cable according to any one of claims 1 to 5.

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