A method and related device for power cable broadband impedance physical simulation based on LC cascade circuit

Abstract

The application discloses a kind of based on LC cascade circuit's power cable broadband impedance physical simulation method and device, belong to power cable state diagnosis technical field.The method is replaced by LC cascade circuit equivalent to replace entity cable, accurately reproduces the broadband impedance characteristic of different voltage grades, different length power cable of 10kV~500kV.Detailed steps include: determining cable unit length distribution parameter, calculating cable basic characteristic parameter, determining LC simulation circuit unit number and lumped parameter, establishing LC cascade circuit model and setting work frequency band.The application greatly reduces the cost and land requirement of experimental platform, can construct standardized cable simulation platform, supports large-scale personnel practical operation training, provides unified calibration reference for instrument performance test, and has significant economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of power cable technology. Background Technology

[0002] Broadband impedance spectroscopy (BIS) is one of the key technologies that has rapidly developed in the field of nondestructive testing of power cables in recent years. Based on the frequency domain reflection principle (FDR), this technology injects a broadband excitation signal at the beginning of the power cable and analyzes the variation of the reflection coefficient with frequency, achieving highly sensitive detection of minute changes such as changes in the cable's physical structure, insulation degradation, and the evolution of local defects. Compared with time domain reflection, broadband impedance spectroscopy has advantages such as richer high-frequency information, stronger anti-interference ability, and greater sensitivity to minute defects, demonstrating significant engineering adaptability in cables of all voltage levels. However, the widespread application of this technology in engineering faces key bottlenecks.

[0003] The closest existing solution in the engineering field is to rely entirely on real cables for broadband impedance testing, which is currently the only way to obtain a true physical response. However, the inventors found that this method is costly, space-consuming, difficult to standardize, and cannot cover the diverse needs of different voltage levels and lengths. This results in a lack of a unified calibration standard for testing instruments and makes data comparison between different institutions difficult. Furthermore, because the high-frequency characteristics of cables vary significantly due to manufacturing tolerances and laying methods, using real cables cannot serve as a unified "impedance standard sample." The disadvantages of the aforementioned existing technologies are: 1. Extremely high construction costs and large land area required; physical cables are expensive, and simulating long-distance transmission requires a huge experimental site; 2. Poor flexibility in scenario adaptation, making it difficult to simultaneously construct standardized simulation environments covering different voltage levels (10kV-500kV) and different lengths within a limited space; 3. Lack of a unified calibration benchmark; due to the use of discrete, non-standardized physical old or new cables, there is a lack of standardized "calibration cable samples" in the industry, resulting in inconsistent performance indicators of BIS testing instruments and widespread false labeling of parameters; 4. Limited talent training; due to the high cost and scarcity of experimental conditions, it is impossible to support large-scale broadband impedance testing practical training.

[0004] Current technologies rely entirely on physical entities to carry electrical signal transmission. Due to the physical characteristics of power cables, their high-frequency impedance characteristics depend on the actual conductor length and insulation structure, making it impossible to adjust their electrical parameters without changing their physical dimensions, and also impossible to directly reproduce their macroscopic transmission behavior using low-cost microelectronic methods. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a physical simulation method for wideband impedance of power cables based on LC cascade circuits.

[0006] This invention primarily addresses the technical problems of existing broadband impedance test platforms for power cables, such as high cost, large footprint, and difficulty in adapting to different types, which prevent large-scale practical training and lack of unified instrument calibration standards.

[0007] The technical solution adopted in this invention is: a method for physical simulation of broadband impedance of power cables based on LC cascaded circuits, characterized in that it includes:

[0008] Determine the distribution parameters per unit length of the cable to be simulated;

[0009] Calculate the basic characteristic parameters of the cable based on the unit length distribution parameters and the total length of the cable to be simulated;

[0010] Calculate the number of LC analog circuit units and lumped parameters based on the basic characteristic parameters of the cable;

[0011] An LC cascaded circuit model is established based on the number of LC analog circuit units and lumped parameters, and the operating frequency band is set according to the upper limit of the network operating frequency.

[0012] The determination of the unit length distribution parameters of the cable to be simulated specifically includes:

[0013] Determine the resistance R0, inductance L0, capacitance G0, and conductance C0 per unit length of the cable:

[0014] (1);

[0015] (2);

[0016] (3);

[0017] (4);

[0018] In the formula, ω=2πf is the angular frequency, and r c and r s These are the cable core radius and the inner radius of the metal sheath, respectively, ρ c and ρ s These represent the resistivity of the cable core and the resistivity of the metal sheath, respectively; μ0 is the permeability of vacuum; ε is the dielectric constant of the dielectric; and σ is the conductivity of the dielectric.

[0019] The calculation of the basic characteristic parameters of the cable based on the unit length distribution parameters and the total length of the cable to be simulated specifically includes:

[0020] At the cable end (i.e., z=0), voltage U(z) and current I(z) are obtained. The traveling voltage U is obtained through equations (5) and (6). + , reverse wave U -With the characteristic impedance Z of the cable c :

[0021] (5);

[0022] (6);

[0023] In the formula, Let α be the propagation constant, β be the attenuation constant of the cable, and β be the phase constant of the cable.

[0024] Cable head reflection coefficient Γ in (ω) is:

[0025] (10);

[0026] First-end input impedance Z in (ω) is:

[0027] (11);

[0028] The cable wave velocity v is:

[0029] (12);

[0030] The equivalent bandwidth at any position z of the cable is:

[0031] (13);

[0032] In the formula, f eq The equivalent frequency is l, the total length of the cable to be simulated is l, and z is the distance between the target position and the beginning of the cable of length l.

[0033] The calculation of the number of LC analog circuit units and lumped parameters based on the basic characteristic parameters of the cable specifically includes:

[0034] In the LC cascade circuit model, one LC unit corresponds to one period of the input impedance spectrum. The number of effective periods, i.e., the number of LC circuit units, N, is defined as the input impedance amplitude |Z|. in The number of peaks encountered as the peak decays from the first maximum value to a preset threshold;

[0035] The number of LC circuit units N is:

[0036] (14);

[0037] Where f * The input impedance magnitude |Z in |The frequency at which the maximum amplitude decays to a preset threshold; the preset threshold is 10% to 30% of the maximum amplitude; ω * To be with f* The corresponding angular frequency; f min The initial frequency is specified; int(.) represents the floor function.

[0038] After obtaining the number of LC elements N, the lumped parameters R, L, G, and C of the LC elements can be obtained by using the cable length l to be simulated and the previously calculated cable distribution parameters R0, L0, G0, and C0.

[0039] (15).

[0040] The step of establishing an LC cascaded circuit model based on the number of LC analog circuit units and lumped parameters, and setting the operating frequency band based on the upper limit of the network operating frequency, specifically includes:

[0041] N LC analog circuit units are connected end to end along the signal transmission direction to form an LC cascaded analog channel, and an input terminal and an output terminal are respectively set at both ends of the analog channel, wherein the equivalent cable length corresponding to each LC analog circuit unit is l / N;

[0042] The unit circuit is constructed according to the lumped parameters R, L, G, C of each LC analog circuit unit. The lumped parameters R and L are set in the series branch of the unit, and the lumped parameters G and C are set in the parallel branch of the unit to form an LC analog circuit unit. In the same simulation channel, each LC analog circuit unit uses the same lumped parameters to simulate a uniform cable segment.

[0043] When it is necessary to simulate cables of different lengths or voltage levels, multiple independent simulation channels can be set up by changing the number N and l of cascaded LC simulation circuit units or changing the lumped parameters R, L, G, C of each LC simulation circuit unit, and the parameters of the LC simulation circuit units in each simulation channel can be configured respectively.

[0044] Based on the characteristic impedance data, the upper frequency f of the covered frequency band max Set an upper limit for the network operating frequency so that the operating frequency of the analog network does not exceed the upper limit frequency f. max ;

[0045] The upper frequency f of the characteristic impedance data coverage band max for:

[0046] (16).

[0047] The present invention also provides a physical simulation device for broadband impedance of power cables based on LC cascaded circuits, comprising:

[0048] The distributed parameter determination module is used to determine the distributed parameters per unit length of the cable to be simulated;

[0049] The feature parameter calculation module is used to calculate the basic feature parameters of the cable based on the unit length distribution parameters and the total length of the cable to be simulated.

[0050] The module for calculating the number of units and lumped parameters is used to calculate the number of units and lumped parameters of the LC analog circuit based on the basic characteristic parameters of the cable.

[0051] The model building and frequency band setting module establishes an LC cascaded circuit model based on the number of LC analog circuit units and lumped parameters, and sets the working frequency band according to the upper limit of the network working frequency.

[0052] The distribution parameter determination module is specifically used for:

[0053] Determine the resistance R0, inductance L0, capacitance G0, and conductance C0 per unit length of the cable:

[0054] (1);

[0055] (2);

[0056] (3);

[0057] (4);

[0058] In the formula, ω=2πf is the angular frequency, and r c and r s These are the cable core radius and the inner radius of the metal sheath, respectively, ρ c and ρ s These represent the resistivity of the cable core and the resistivity of the metal sheath, respectively; μ0 is the permeability of vacuum; ε is the dielectric constant of the dielectric; and σ is the conductivity of the dielectric.

[0059] The feature parameter calculation module is specifically used for:

[0060] At the cable end (i.e., z=0), voltage U(z) and current I(z) are obtained. The traveling voltage U is obtained through equations (5) and (6). + , reverse wave U - With the characteristic impedance Z of the cable c :

[0061] (5);

[0062] (6);

[0063] In the formula, Let α be the propagation constant, β be the attenuation constant of the cable, and β be the phase constant of the cable.

[0064] Cable head reflection coefficient Γ in (ω) is:

[0065] (10);

[0066] First-end input impedance Z in (ω) is:

[0067] (11);

[0068] The cable wave velocity v is:

[0069] (12);

[0070] The equivalent bandwidth at any position z of the cable is:

[0071] (13);

[0072] In the formula, f eq The equivalent frequency is l, the total length of the cable to be simulated is l, and z is the distance between the target position and the beginning of the cable of length l.

[0073] The module for calculating the number of units and lumped parameters is specifically used for:

[0074] In the LC cascade circuit model, one LC unit corresponds to one period of the input impedance spectrum. The number of effective periods, i.e., the number of LC circuit units, N, is defined as the input impedance amplitude |Z|. in The number of peaks encountered as the peak decays from the first maximum value to a preset threshold;

[0075] The number of LC circuit units N is:

[0076] (14);

[0077] Where f * The input impedance magnitude |Z in |The frequency at which the maximum amplitude decays to a preset threshold; the preset threshold is 10% to 30% of the maximum amplitude; ω * To be with f * The corresponding angular frequency; f min The initial frequency is specified; int(.) represents the floor function.

[0078] After obtaining the number of LC elements N, the lumped parameters R, L, G, and C of the LC elements can be obtained by using the cable length l to be simulated and the previously calculated cable distribution parameters R0, L0, G0, and C0.

[0079] (15).

[0080] The model building and frequency band setting module is specifically used for:

[0081] N LC analog circuit units are connected end to end along the signal transmission direction to form an LC cascaded analog channel, and an input terminal and an output terminal are respectively set at both ends of the analog channel, wherein the equivalent cable length corresponding to each LC analog circuit unit is l / N;

[0082] The unit circuit is constructed according to the lumped parameters R, L, G, C of each LC analog circuit unit. The lumped parameters R and L are set in the series branch of the unit, and the lumped parameters G and C are set in the parallel branch of the unit to form an LC analog circuit unit. In the same simulation channel, each LC analog circuit unit uses the same lumped parameters to simulate a uniform cable segment.

[0083] When it is necessary to simulate cables of different lengths or voltage levels, multiple independent simulation channels can be set up by changing the number N and l of cascaded LC simulation circuit units or changing the lumped parameters R, L, G, C of each LC simulation circuit unit, and the parameters of the LC simulation circuit units in each simulation channel can be configured respectively.

[0084] Based on the characteristic impedance data, the upper frequency f of the covered frequency band max Set an upper limit for the network operating frequency so that the operating frequency of the analog network does not exceed the upper limit frequency f. max ;

[0085] The upper frequency f of the characteristic impedance data coverage band max for:

[0086] (16).

[0087] The present invention also provides a multi-channel cable characteristic simulation device, comprising multiple independent simulation channels for parallel simulation of broadband impedance characteristics of cables of different lengths; each simulation channel is composed of N LC simulation circuit units connected end to end along the signal transmission direction; the parameters of the LC simulation circuit units in each simulation channel are set using the above-mentioned physical simulation method of broadband impedance of power cables based on LC cascade circuit.

[0088] The capacitance and inductance parameters of all LC analog circuit units within the same channel are kept consistent to ensure the continuity of the simulation length; the capacitance and inductance parameters of LC analog circuit units in different channels are set differently to achieve parallel simulation of the wideband impedance characteristics of cables of different lengths.

[0089] Another aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the physical simulation method for broadband impedance of power cables based on LC cascaded circuits as described in the first aspect.

[0090] In another aspect, the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the physical simulation method for broadband impedance of power cables based on LC cascaded circuits as described in the first aspect.

[0091] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0092] 1) Significantly reduces costs and space requirements. Existing technologies use bulky physical cables, while this invention uses miniaturized PCB circuits to condense several kilometers of cable onto a single PCB board. This eliminates the need for expensive cable materials and large experimental spaces, solving the problem that universities and training institutions cannot build large-scale experimental platforms.

[0093] 2) Provides a high-precision standard calibration benchmark. Existing technologies lack standards, but this invention provides a reproducible standard "calibration component" with precise and controllable parameters. This solves the problem of the lack of a unified calibration source for broadband impedance testing instruments in the industry, which helps to standardize the instrument market and improve the reliability of power grid operation and maintenance testing.

[0094] 3) Enables flexible multi-scenario simulation. Existing technologies cannot flexibly adjust parameters. This invention can flexibly simulate the characteristics of cables of different voltage levels and lengths from 10kV to 500kV by adjusting circuit parameters, changing the L, C values ​​and the number of cascade stages, which greatly enriches the scenario coverage of experiments and training. Attached Figure Description

[0095] Figure 1 This is a cross-sectional view of an XLPE cable.

[0096] Figure 2 It is the input impedance spectrum of a 10kV cable and an LC circuit.

[0097] Figure 3 It is a circuit topology diagram of a simulated cable model.

[0098] Figure 4 This is an actual diagram of a simulated cable model. Detailed Implementation

[0099] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0100] This invention proposes a cable simulation architecture based on LC cascaded circuits. It uses discrete inductors (L) and capacitors (C) in a cascaded topology to equivalently replace high-voltage power cables, providing a technical solution for wideband impedance characteristic reproduction. A specific cable parameter to circuit parameter mapping algorithm is employed, including: deriving distributed parameters from the cable's physical structure; determining the number of simulation units and the length of a single simulation section based on wave velocity and equivalent bandwidth; and finally, determining the quantization method for circuit component values. This invention also provides a standardized multi-channel hardware implementation device, integrating multiple sets of LC channels with different parameters on a PCB board, connected via an SMA interface, enabling a simulator device capable of simultaneously simulating the characteristics of cables of different specifications.

[0101] The present invention provides a method for physical simulation of broadband impedance of power cables based on LC cascaded circuits. This method uses LC cascaded circuits to replace physical cables and consists of three main parts: collection of cable distributed parameters, simulation calculation of broadband impedance characteristics, and physical construction. Finally, a case study is used to demonstrate the feasibility of this method.

[0102] S1. Collection and Calculation of Cable Distribution Parameters

[0103] Based on current standards (DL / T 838, GB / T 3956) and enterprise technical documents, collect physical parameters such as voltage rating, length, core radius, insulation type, and cable type of the cable object to be simulated. The following method uses XLPE cable (e.g., Figure 1 (As shown) for example:

[0104] (1) Determine the core radius r of the target voltage level c ( Figure 1 The outer radius of the middle conductor and the radius r of the metal shielding layer s ( Figure 1 (inner radius of the metal shield), where r c Determined by the nominal cross-sectional area of ​​the conductor and the compaction process; r s Then by r c The thicknesses of the superimposed conductor shielding layer, insulation layer, and metallic shielding layer are determined. The insulation layer thickness needs to be determined by referring to standards based on the voltage level of the cable to be simulated (e.g., 10kV~500kV).

[0105] (2) Determine the resistivity ρ of the cable core conductor c and the resistivity ρ of the shielding layer s (e.g., the resistivity of copper or aluminum materials); determine the dielectric constant ε and conductivity σ of the insulating medium.

[0106] According to transmission line theory, the resistance R0 and inductance L0 per unit length of the cable can be expressed by equations (1) and (2).

[0107] (1)

[0108] (2)

[0109] In the formula, ω=2πf is the angular frequency, and r c and r s These are the cable core radius and the metal shielding radius, respectively, ρ c and ρ s These represent the resistivity of the cable core and the resistivity of the metal shielding layer, respectively, while μ0 is the permeability of vacuum.

[0110] The capacitance G0 and conductance C0 per unit length of the cable can be expressed by equations (3) and (4):

[0111] (3)

[0112] (4)

[0113] In the formula, ε is the dielectric constant of the dielectric, and σ is the conductivity of the dielectric.

[0114] Based on the known permeability, conductivity, and dielectric constant of the dielectric, the precise physical parameters are substituted into the aforementioned formula to calculate the power cable distribution parameters, thus forming the power cable body parameters for different voltage levels. According to the differentiated equivalent analysis of cable component types, based on the body distribution parameters, the joint is equivalent to the body with added extra insulation (adjusting the inner radius of the shielding layer to adapt to parameter changes), and the terminal is equivalent to the intermediate joint and reuses the joint parameter system. The distribution parameters of each component are determined respectively. The cable body, joint, and terminal distribution parameters are calculated according to equations (1)-(4). These parameters will be used for subsequent calculations of the cable input broadband impedance spectrum and wave velocity.

[0115] S2, Wideband Impedance Characteristic Simulation Calculation

[0116] After obtaining the cable's distributed parameters, the next step is to calculate the cable's broadband impedance characteristics based on these parameters, including the cable's input impedance spectrum, wave velocity, and equivalent bandwidth.

[0117] (1) Calculation of input broadband impedance of cable

[0118] The key to this method lies in simulating the broadband impedance spectrum of the cable. Therefore, the first step is to calculate the broadband impedance of the cable. The voltage U(z) and current I(z) at any position z on the cable body (assuming z=0 at the beginning and z=1 at the end) can be expressed as the superposition of the incident wave (forward wave) and the reflected wave (backward wave).

[0119] (5)

[0120] Among them U + U -These are the forward input emission voltage and the reverse transmission reflected voltage of the cable, respectively. These two parameters are crucial for subsequent calculations of the input reflection coefficient. Z is a propagation constant used to describe the attenuation and phase change characteristics of a test signal as it propagates along the cable. c The characteristic impedance of the cable can be expressed as:

[0121] (6)

[0122] Where R0, L0, G0, and C0 are the cable distribution parameters calculated by equations (1) to (4); α represents the cable attenuation constant, indicating the rate at which the amplitude of the electromagnetic wave decays exponentially with distance during propagation; β represents the cable phase constant, indicating the radian of phase change per unit distance propagated by the electromagnetic wave; α and β can be expressed as:

[0123] (7)

[0124] Wherein, under the high-frequency condition that R0 << ωL0 and G0 << ωC0 (R0 / ωL0 ≤ 0.1 and G0 / ωC0 ≤ 0.1), α and β can be simplified to:

[0125] (8)

[0126] (9)

[0127] At the cable end (i.e., z=0), the voltage U(z) and current I(z) are obtained, and then the voltage traveling wave U is obtained through equations (5) and (6). + , reverse wave U - With characteristic impedance Z c Calculate its input reflection coefficient Γ at the front end. in (ω) and the input impedance Z at the beginning in (ω):

[0128] (10)

[0129] First-end input impedance Z in (ω) can be derived from the reflection coefficient input at the head end.

[0130] (11)

[0131] (2) Calculate the cable wave velocity

[0132] Based on the cable unit length distribution parameters obtained in the previous step and the classical formula for calculating the resonant wave velocity of electromagnetic waves propagating in a uniform transmission line in transmission line theory, the wave velocity can be calculated, and its expression is:

[0133] (12)

[0134] In the formula, v is the propagation speed of electromagnetic waves in the cable, in m / s; L0 is the distributed inductance per unit length of the cable, in H / m; and C0 is the distributed capacitance per unit length of the cable, in F / m.

[0135] (3) Calculate the equivalent bandwidth of the cable

[0136] Based on equivalent frequency f eq The formula for the equivalent bandwidth at any position z of the cable can be derived:

[0137] (13)

[0138] In the formula, FT(l,z,v) is the equivalent bandwidth of the cable at position z, l is the total length of the cable, z is the distance between the target position and the beginning of the cable of length l, and v is the cable wave velocity.

[0139] S3. Calculate the number of units and lumped parameters of the LC analog circuit.

[0140] Once the broadband impedance characteristics of the cable are determined, the LC cascade circuit can be designed. The first step is to determine the number of LC units. The LC cascade circuit model is a circuit model composed of multiple Pi-type LC units cascaded together. In the LC cascade circuit model, one LC unit corresponds to one period in the input impedance spectrum. The number of effective periods N (also the number of LC analog circuit units) is defined as the input impedance amplitude |Z. in The number of peaks encountered when the signal decays from its first maximum peak to 20% (a preset threshold) reflects the bandwidth of the signal's effective transmission in the cable. The preset threshold of 20% is chosen to preserve the main resonant characteristics of the input impedance spectrum while eliminating the influence of subsequent low-amplitude weak peaks and noise disturbances on the determination of the number of LC units. This ensures that the determined number of units balances the ability to reproduce wideband impedance characteristics with the feasibility of actual component size. In other embodiments, the preset ratio can also be other values ​​between 10% and 30%, with 20% being a preferred value. The formula for the number of effective cycles N is...

[0141] (14)

[0142] Where f * The input impedance magnitude |Z in The frequency at which the maximum amplitude decays to 20%, ω * To be with f * The corresponding angular frequency, ω * with f * They can be converted to each other according to equation (14); f minThe starting frequency is 0Hz; FT(l,z,v) is the equivalent bandwidth of the cable at position z, which can be calculated by equation (13).

[0143] After obtaining the number of LC elements N, the lumped parameters R, L, G, and C of the LC elements can be obtained by using the required cable length l to be simulated and the previously calculated cable distribution parameters R0, L0, G0, and C0. The calculation formulas are as follows:

[0144] (15)

[0145] S4. Establish an LC cascade circuit model and calculate the upper limit frequency.

[0146] The unit circuit is constructed according to the lumped parameters R, L, G, C of each LC analog circuit unit. The lumped parameters R and L are set in the series branch of the unit, and the lumped parameters G and C are set in the parallel branch of the unit to form an LC analog circuit unit. In the same simulation channel, each LC analog circuit unit uses the same lumped parameters to simulate a uniform cable segment.

[0147] When it is necessary to simulate cables of different lengths or voltage levels, multiple independent simulation channels can be set up by changing the number N and l of cascaded LC simulation circuit units or changing the lumped parameters R, L, G, C of each LC simulation circuit unit, and the parameters of the LC simulation circuit units in each simulation channel can be configured respectively.

[0148] After obtaining the parameters of the LC cascade unit, it is also necessary to avoid severe dispersion or reflection distortion of signals in the analog unit under high-frequency conditions. The upper limit of the operating frequency of the analog circuit must meet a specific constraint relationship with the cable length. This constraint relationship can be quantified in engineering practice using an empirical formula, namely, the upper limit frequency f of the characteristic impedance data coverage band. max The calculation formula is

[0149] (16)

[0150] In the formula, f max The upper limit of the frequency band covered by the characteristic impedance data of the cable is denoted by l, where l is the total length of the cable, L0 is the distributed inductance per unit length of the cable, and C0 is the distributed capacitance per unit length of the cable.

[0151] S5, Physical construction of broadband impedance simulation for power cables

[0152] (1) Simulation Case

[0153] This section uses the physical parameters of a 200 m 10 kV XLPE cable for simulation calculations. The parameter settings are shown in Table 1.

[0154] Table 1. Simulation cable model parameters

[0155]

[0156] The distributed parameters of the 10 kV XLPE cable and the lumped parameters of the LC cascade circuit (N=10) were calculated based on the parameters in Table 1, as shown in Table 2.

[0157] Table 2 Parameters of 10 kV Cable and LC Circuit

[0158]

[0159] The input impedance spectrum of a 10 kV / 200 m cable and an LC cascade circuit (N=10) was calculated based on the above formula and parameters, with a frequency range of 10 Hz to 10 MHz. Figure 2 As shown.

[0160] A small number of LC units have been able to reproduce the amplitude and periodic relationship of the maximum and minimum values ​​of the input impedance spectrum of real cables well in the low-frequency band, proving that the LC cascade circuit model can accurately simulate the broadband impedance characteristics of real cables.

[0161] (2) Physical simulation

[0162] To initially verify the effectiveness of this architecture for simulating cable characteristics, an experimental model was constructed using common, general-purpose capacitors and inductors as core components. The capacitors and inductors used in the model were selected from commercially available surface-mount capacitors, and their parameter accuracy met the requirements for impedance simulation trend matching in the initial verification stage. All LC units were soldered according to an LC cascade circuit topology.

[0163] The model is based on an LC ladder network architecture and has four independent simulation channels (CH1~CH4). It adopts the configuration principle of unified unit parameters in the same channel and differentiated parameters between channels: the capacitance and inductance parameters of all LC simulation units in the same channel are kept consistent to ensure the continuity of the simulation length; the LC parameters between channels are differentiated to achieve parallel simulation of the broadband impedance characteristics of cables of different lengths, providing multiple sets of comparative samples for subsequent validity verification. Figure 3 , Figure 4 It is a circuit topology diagram and an actual diagram of a simulated cable model.

[0164] This invention also provides a physical simulation device for broadband impedance of power cables based on LC cascaded circuits, comprising:

[0165] The distributed parameter determination module is used to determine the distributed parameters per unit length of the cable to be simulated;

[0166] The feature parameter calculation module is used to calculate the basic feature parameters of the cable based on the unit length distribution parameters and the total length of the cable to be simulated.

[0167] The module for calculating the number of units and lumped parameters is used to calculate the number of units and lumped parameters of the LC analog circuit based on the basic characteristic parameters of the cable.

[0168] The model building and frequency band setting module establishes an LC cascaded circuit model based on the number of LC analog circuit units and lumped parameters, and sets the working frequency band according to the upper limit of the network working frequency.

[0169] The distribution parameter determination module is specifically used for:

[0170] Determine the resistance R0, inductance L0, capacitance G0, and conductance C0 per unit length of the cable:

[0171] (1);

[0172] (2);

[0173] (3);

[0174] (4);

[0175] In the formula, ω=2πf is the angular frequency, and r c and r s These are the cable core radius and the inner radius of the metal sheath, respectively, ρ c and ρ s These represent the resistivity of the cable core and the resistivity of the metal sheath, respectively; μ0 is the permeability of vacuum; ε is the dielectric constant of the dielectric; and σ is the conductivity of the dielectric.

[0176] The feature parameter calculation module is specifically used for:

[0177] At the cable end (i.e., z=0), voltage U(z) and current I(z) are obtained. The traveling voltage U is obtained through equations (5) and (6). + , reverse wave U - With the characteristic impedance Z of the cable c :

[0178] (5);

[0179] (6);

[0180] In the formula, Let α be the propagation constant, β be the attenuation constant of the cable, and β be the phase constant of the cable.

[0181] Cable head reflection coefficient Γ in (ω) is:

[0182] (10);

[0183] First-end input impedance Z in (ω) is:

[0184] (11);

[0185] The cable wave velocity v is:

[0186] (12);

[0187] The equivalent bandwidth at any position z of the cable is:

[0188] (13);

[0189] In the formula, f eq The equivalent frequency is l, the total length of the cable to be simulated is l, and z is the distance between the target position and the beginning of the cable of length l.

[0190] The module for calculating the number of units and lumped parameters is specifically used for:

[0191] In the LC cascade circuit model, one LC unit corresponds to one period of the input impedance spectrum. The number of effective periods, i.e., the number of LC circuit units, N, is defined as the input impedance amplitude |Z|. in The number of peaks encountered as the peak decays from the first maximum value to a preset threshold;

[0192] The number of LC circuit units N is:

[0193] (14);

[0194] Where f * The input impedance magnitude |Z in |The frequency at which the maximum amplitude decays to a preset threshold; the preset threshold is 10% to 30% of the maximum amplitude; ω * To be with f * The corresponding angular frequency; f min The initial frequency is specified; int(.) represents the floor function.

[0195] After obtaining the number of LC elements N, the lumped parameters R, L, G, and C of the LC elements can be obtained by using the cable length l to be simulated and the previously calculated cable distribution parameters R0, L0, G0, and C0.

[0196] (15).

[0197] The model building and frequency band setting module is specifically used for:

[0198] N LC analog circuit units are connected end to end along the signal transmission direction to form an LC cascaded analog channel, and an input terminal and an output terminal are respectively set at both ends of the analog channel, wherein the equivalent cable length corresponding to each LC analog circuit unit is l / N;

[0199] The unit circuit is constructed according to the lumped parameters R, L, G, C of each LC analog circuit unit. The lumped parameters R and L are set in the series branch of the unit, and the lumped parameters G and C are set in the parallel branch of the unit to form an LC analog circuit unit. In the same simulation channel, each LC analog circuit unit uses the same lumped parameters to simulate a uniform cable segment.

[0200] When it is necessary to simulate cables of different lengths or voltage levels, multiple independent simulation channels can be set up by changing the number N and l of cascaded LC simulation circuit units or changing the lumped parameters R, L, G, C of each LC simulation circuit unit, and the parameters of the LC simulation circuit units in each simulation channel can be configured respectively.

[0201] Based on the characteristic impedance data, the upper frequency f of the covered frequency band max Set an upper limit for the network operating frequency so that the operating frequency of the analog network does not exceed the upper limit frequency f. max ;

[0202] The upper frequency f of the characteristic impedance data coverage band max for:

[0203] (16).

[0204] The present invention also provides a multi-channel cable characteristic simulation device, including multiple independent simulation channels; the simulation channels are set based on an LC cascaded circuit model; the capacitance and inductance parameters of all LC simulation circuit units in the same channel are kept consistent to ensure the continuity of the simulation length; the capacitance and inductance parameters of the LC simulation circuit units in different channels are set differently to achieve parallel simulation of the broadband impedance characteristics of cables of different lengths.

[0205] Another aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the physical simulation method for broadband impedance of power cables based on LC cascaded circuits as described in the first aspect.

[0206] In another aspect, the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the physical simulation method for broadband impedance of power cables based on LC cascaded circuits as described in the first aspect.

[0207] This invention employs a "low-cost hardware equivalent" architecture, utilizing discrete inductor and capacitor units to construct LC cascaded circuits, accurately reproducing the high-frequency transmission and wideband impedance characteristics of power cables of different voltage levels and lengths from 10kV to 500kV. The aim is to significantly reduce the cost and footprint of the experimental platform, constructing a standardized "cable simulation platform" that can support large-scale practical training for personnel and provide a unified calibration benchmark for instrument performance verification.

[0208] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0209] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0210] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0211] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0212] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for physical simulation of broadband impedance of power cables based on LC cascaded circuits, characterized in that: include: Determine the distribution parameters per unit length of the cable to be simulated; Calculate the basic characteristic parameters of the cable based on the unit length distribution parameters and the total length of the cable to be simulated; Calculate the number of LC analog circuit units and lumped parameters based on the basic characteristic parameters of the cable; An LC cascaded circuit model is established based on the number of LC analog circuit units and lumped parameters, and the operating frequency band is set according to the upper limit of the network operating frequency.

2. The method for physical simulation of broadband impedance of power cables based on LC cascaded circuits according to claim 1, characterized in that: The determination of the unit length distribution parameters of the cable to be simulated specifically includes: Determine the resistance R0, inductance L0, capacitance G0, and conductance C0 per unit length of the cable: (1)； (2)； (3)； (4)； In the formula, ω=2πf is the angular frequency, and r c and r s These are the cable core radius and the inner radius of the metal sheath, respectively, ρ c and ρ s These represent the resistivity of the cable core and the resistivity of the metal sheath, respectively; μ0 is the permeability of vacuum; ε is the dielectric constant of the dielectric; and σ is the conductivity of the dielectric.

3. The method for physical simulation of broadband impedance of power cables based on LC cascaded circuits according to claim 2, characterized in that: The calculation of the basic characteristic parameters of the cable based on the unit length distribution parameters and the total length of the cable to be simulated specifically includes: At the cable end, voltage U(z) and current I(z) are obtained, and the voltage traveling wave U is obtained through equations (5) and (6). + , reverse wave U - With the characteristic impedance Z of the cable c : (5)； (6)； In the formula, Let α be the propagation constant, β be the attenuation constant of the cable, and β be the phase constant of the cable. Cable head reflection coefficient Γ in (ω) is: (10)； First-end input impedance Z in (ω) is: (11)； The cable wave velocity v is: (12)； The equivalent bandwidth at any position z of the cable is: (13)； In the formula, f eq The equivalent frequency is l, the total length of the cable to be simulated is l, and z is the distance between the target position and the beginning of the cable of length l.

4. The method for physical simulation of broadband impedance of power cables based on LC cascaded circuits according to claim 3, characterized in that: The calculation of the number of LC analog circuit units and lumped parameters based on the basic characteristic parameters of the cable specifically includes: In the LC cascade circuit model, one LC unit corresponds to one period of the input impedance spectrum. The number of effective periods, i.e., the number of LC circuit units, N, is defined as the input impedance amplitude |Z|. in The number of peaks encountered as the peak decays from the first maximum value to a preset threshold; The number of LC circuit units N is: (14)； Where f * The input impedance magnitude |Z in |The frequency at which the maximum amplitude decays to a preset threshold; the preset threshold is 10% to 30% of the maximum amplitude; ω * To be with f * The corresponding angular frequency; f min The initial frequency is specified; int(.) represents the floor function. After obtaining the number of LC elements N, the lumped parameters R, L, G, and C of the LC elements can be obtained by using the cable length l to be simulated and the previously calculated cable distribution parameters R0, L0, G0, and C0. (15)。 5. The method for physical simulation of broadband impedance of power cables based on LC cascaded circuits according to claim 4, characterized in that: The step of establishing an LC cascaded circuit model based on the number of LC analog circuit units and lumped parameters, and setting the operating frequency band based on the upper limit of the network operating frequency, specifically includes: N LC analog circuit units are connected end to end along the signal transmission direction to form an LC cascaded analog channel, and an input terminal and an output terminal are respectively set at both ends of the analog channel, wherein the equivalent cable length corresponding to each LC analog circuit unit is l / N; The unit circuit is constructed according to the lumped parameters R, L, G, C of each LC analog circuit unit. The lumped parameters R and L are set in the series branch of the unit, and the lumped parameters G and C are set in the parallel branch of the unit to form an LC analog circuit unit. In the same simulation channel, each LC analog circuit unit uses the same lumped parameters to simulate a uniform cable segment. When it is necessary to simulate cables of different lengths or voltage levels, multiple independent simulation channels can be set up by changing the number N and l of cascaded LC simulation circuit units or changing the lumped parameters R, L, G, C of each LC simulation circuit unit, and the parameters of the LC simulation circuit units in each simulation channel can be configured respectively. Based on the characteristic impedance data, the upper frequency f of the covered frequency band max Set an upper limit for the network operating frequency so that the operating frequency of the analog network does not exceed the upper limit frequency f. max ; The upper frequency f of the characteristic impedance data coverage band max for: (16)。 6. A physical simulation device for broadband impedance of power cables based on LC cascaded circuits, characterized in that: include: The distributed parameter determination module is used to determine the distributed parameters per unit length of the cable to be simulated; The feature parameter calculation module is used to calculate the basic feature parameters of the cable based on the unit length distribution parameters and the total length of the cable to be simulated. The module for calculating the number of units and lumped parameters is used to calculate the number of units and lumped parameters of the LC analog circuit based on the basic characteristic parameters of the cable. The model building and frequency band setting module establishes an LC cascade circuit model based on the number of LC analog circuit units and lumped parameters, and sets the working frequency band according to the upper limit of the network working frequency.

7. The power cable broadband impedance physical simulation device based on LC cascaded circuit according to claim 6, characterized in that: The distribution parameter determination module is specifically used for: Determine the resistance R0, inductance L0, capacitance G0, and conductance C0 per unit length of the cable: (1)； (2)； (3)； (4)； In the formula, ω=2πf is the angular frequency, and r c and r s These are the cable core radius and the inner radius of the metal sheath, respectively, ρ c and ρ s These represent the resistivity of the cable core and the resistivity of the metal sheath, respectively; μ0 is the permeability of vacuum; ε is the dielectric constant of the dielectric; and σ is the conductivity of the dielectric.

8. The power cable broadband impedance physical simulation device based on LC cascaded circuit according to claim 7, characterized in that: The feature parameter calculation module is specifically used for: At the cable end, voltage U(z) and current I(z) are obtained, and the voltage traveling wave U is obtained through equations (5) and (6). + , reverse wave U - With the characteristic impedance Z of the cable c : (5)； (6)； In the formula, Let α be the propagation constant, β be the attenuation constant of the cable, and β be the phase constant of the cable. Cable head reflection coefficient Γ in (ω) is: (10)； First-end input impedance Z in (ω) is: (11)； The cable wave velocity v is: (12)； The equivalent bandwidth at any position z of the cable is: (13)； In the formula, f eq The equivalent frequency is l, the total length of the cable to be simulated is l, and z is the distance between the target position and the beginning of the cable of length l.

9. The power cable broadband impedance physical simulation device based on LC cascaded circuit according to claim 8, characterized in that: The module for calculating the number of units and lumped parameters is specifically used for: In the LC cascade circuit model, one LC unit corresponds to one period of the input impedance spectrum. The number of effective periods, i.e., the number of LC circuit units, N, is defined as the input impedance amplitude |Z|. in The number of peaks encountered as the peak decays from the first maximum value to a preset threshold; The number of LC circuit units N is: (14)； Where f * The input impedance magnitude |Z in |The frequency at which the maximum amplitude decays to a preset threshold; the preset threshold is 10% to 30% of the maximum amplitude; ω * To be with f * The corresponding angular frequency; f min The initial frequency is specified; int(.) represents the floor function. After obtaining the number of LC elements N, the lumped parameters R, L, G, and C of the LC elements can be obtained by using the cable length l to be simulated and the previously calculated cable distribution parameters R0, L0, G0, and C0. (15)。 10. The power cable broadband impedance physical simulation device based on LC cascaded circuit according to claim 9, characterized in that: The model building and frequency band setting module is specifically used for: N LC analog circuit units are connected end to end along the signal transmission direction to form an LC cascaded analog channel, and an input terminal and an output terminal are respectively set at both ends of the analog channel, wherein the equivalent cable length corresponding to each LC analog circuit unit is l / N; The unit circuit is constructed according to the lumped parameters R, L, G, C of each LC analog circuit unit. The lumped parameters R and L are set in the series branch of the unit, and the lumped parameters G and C are set in the parallel branch of the unit to form an LC analog circuit unit. In the same simulation channel, each LC analog circuit unit uses the same lumped parameters to simulate a uniform cable segment. When it is necessary to simulate cables of different lengths or voltage levels, multiple independent simulation channels can be set up by changing the number N and l of cascaded LC simulation circuit units or changing the lumped parameters R, L, G, C of each LC simulation circuit unit, and the parameters of the LC simulation circuit units in each simulation channel can be configured respectively. Based on the characteristic impedance data, the upper frequency f of the covered frequency band max Set an upper limit for the network operating frequency so that the operating frequency of the analog network does not exceed the upper limit frequency f. max ; The upper frequency f of the characteristic impedance data coverage band max for: (16)。 11. A multi-channel cable characteristic simulation device, characterized in that: It includes multiple independent simulation channels for parallel simulation of broadband impedance characteristics of cables of different lengths; each simulation channel is composed of N LC simulation circuit units connected end to end along the signal transmission direction; the parameters of the LC simulation circuit units in each simulation channel are set using the physical simulation method of broadband impedance of power cables based on LC cascaded circuits as described in any one of claims 1-5.

12. An electronic device, characterized in that: It includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the physical simulation method for broadband impedance of power cables based on LC cascaded circuits as described in any one of claims 1-5.

13. A non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for physical simulation of broadband impedance of power cables based on LC cascaded circuits as described in any one of claims 1-5.

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