A simulation method and device for harmonic detection cable joint interface pressure and a medium

Abstract

The application provides a simulation method and device for harmonic detection of cable joint interface pressure and a medium. The method comprises the following steps: modeling a simulation geometric model of a cable intermediate joint, and setting an ultrasonic excitation source; modeling through a nonlinear spring damper to obtain a cable joint pressure model; simulating nonlinear ultrasonic detection of the cable joint interface pressure, and obtaining a frequency spectrum diagram at each point probe. Through modeling of the nonlinear spring damper on the cable joint model, the nonlinear interaction at the interface of the cable intermediate joint is simulated, the change of the harmonic characteristics when the interface pressure changes is deeply explored by using the nonlinear harmonic detection principle, the relationship between the two is established, the state of the cable intermediate joint under various interface pressures is accurately simulated, the pressure at the interface of the cable intermediate joint is fully considered, and simulation analysis is performed on the cable joint interface pressure detection by establishing a new interface nonlinear model.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment condition monitoring technology, and more specifically, to a simulation method, apparatus, and medium for detecting harmonic stress at the interface of a cable joint. Background Technology

[0002] With the continued deepening of urbanization in China, the scale of cable equipment in urban power grids is constantly increasing. Statistics show that, excluding damage from external forces, 70% of cable faults are caused by cable accessory failures. The silicone rubber-cross-linked polyethylene (XLPE) composite interface between cable accessories and the cable body experiences partial discharge due to electric field stress concentration, leading to insulation breakdown. This makes cable accessories a high-risk location for cable line faults. In other words, in power systems, the interface pressure at cable joints has a significant impact on their performance and safety.

[0003] Traditional testing methods have limitations, either damaging the joint structure or failing to accurately reflect the true pressure. Currently, few researchers in simulation have established three-dimensional models to study the relationship between ultrasonic harmonic parameters and pressure, resulting in a bottleneck in experimental research on the relationship between interfacial pressure and ultrasonic harmonics. Summary of the Invention

[0004] In view of this, the present invention proposes a simulation method, device and medium for harmonic detection of cable joint interface pressure, thereby studying the relationship between interface pressure and ultrasonic harmonic amplitude, providing support for further experimental research methods, and aiming to solve the problem that the existing experimental research on the relationship between interface pressure and ultrasonic harmonics is currently lacking.

[0005] On one hand, this invention proposes a simulation method for harmonic detection of cable joint interface pressure. The method includes the following steps: modeling a simulation geometric model of the cable joint, and setting an ultrasonic excitation source on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves, thereby obtaining a cable joint model; setting spring stiffness and spring force at the contact interface between the upper and lower layers of the cable joint model to obtain a cable joint pressure model, thereby simulating the nonlinear interaction force at the interface of the cable joint through the damping of a nonlinear spring damper; performing nonlinear ultrasonic detection of the cable joint interface pressure on the cable joint pressure model, and obtaining the spectrum diagram at each probe point on the cable joint pressure model, thereby obtaining the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram.

[0006] Furthermore, the above-mentioned simulation method for harmonic detection of cable joint interface pressure, wherein the modeling of the simulation geometric model of the cable intermediate joint and the setting of an ultrasonic excitation source on the upper surface of the first layer of the model to simulate ultrasonic wave emission, includes the following sub-steps: obtaining the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint; based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint, performing an equivalent transformation on the cable intermediate joint, establishing a cuboid three-dimensional geometric model corresponding to the cable intermediate joint, and setting the material and material parameters of the upper silicone rubber model and the lower cross-linked polyethylene model in the cuboid three-dimensional geometric model; wherein the cuboid three-dimensional geometric model includes an upper silicone rubber model and a lower cross-linked polyethylene model, the thickness of the upper silicone rubber model being adapted to the silicone rubber layer in the cable intermediate joint, and the thickness of the lower cross-linked polyethylene model being... The thickness of the cross-linked polyethylene model is adapted to the thickness of the cross-linked polyethylene layer in the cable joint; the material parameters include: elastic modulus, density, Poisson's ratio, and damping ratio; a piecewise function is set on the upper surface of the upper silicone rubber model in the cuboid three-dimensional geometric model, and a specified displacement is added at the middle position of the upper surface of the upper silicone rubber model as an excitation function to set the ultrasonic excitation source to simulate the emission of ultrasonic waves; the boundary conditions of the cuboid three-dimensional geometric model are set, and the two sides of the cuboid three-dimensional geometric model are set as low-reflection boundaries; based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene, tetrahedral meshes are established for the upper silicone rubber model and the lower cross-linked polyethylene model respectively; the calculation setting sub-step is used to determine and set the calculation mode of the nonlinear ultrasonic detection cable joint interface pressure simulation as transient calculation.

[0007] Furthermore, in the above simulation method for harmonic detection of cable joint interface pressure, the excitation function F corresponding to the specified displacement in solid mechanics is:

[0008] F=A(1-cos(2*π*f*t / n))*sin(2*π*f*t);

[0009] Where A is the amplitude of the excitation signal, set to 500nm; f is the frequency of the excitation signal, set to 26165Hz; n is the number of periods of the excitation wave, set to 10; and t is the excitation signal time.

[0010] Furthermore, the above-mentioned simulation method for harmonic detection of cable joint interface pressure determines the damping ratio of the corresponding material based on the mass damping and stiffness damping of the corresponding material; wherein, the damping ratio is determined using the following formula:

[0011]

[0012] Where μ is the damping ratio of the corresponding material; α is the mass damping of the corresponding material; ω is the frequency of the corresponding material; and β is the stiffness damping of the corresponding material.

[0013] Furthermore, the above-mentioned simulation method for harmonic detection cable joint interface pressure, wherein setting spring stiffness and spring force at the upper and lower contact interfaces of the cable joint model to obtain a cable joint pressure model includes the following steps: setting the contact interface stiffness at the contact interface between the two insulation layers in the cable joint model to the spring stiffness in a nonlinear spring damper; setting the interface pressure at the contact interface between the two insulation layers in the cable joint model to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers of the interface, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

[0014] Furthermore, in the above simulation method for harmonic detection cable joint interface pressure, the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers of the interface is calculated using the following formula:

[0015] △F=F st —F dt ;

[0016] Where ΔF is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F represents the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model. dt This represents the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0017] Furthermore, in the above-mentioned simulation method for harmonic detection of cable joint interface pressure, the spring force per unit area on the lower surface of the upper silicone rubber model in the cable joint model is calculated using the following formula:

[0018]

[0019] Where a = 4, b = 5, Z0 = 0.1 nm, k1 = 5 × 10¹² N / m 3 k1 = 3 × 10¹² N / m 3 , Δz represents the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0020] The spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model is calculated using the following formula:

[0021]

[0022] Where b = 5, Z0 = 0.1 nm, and γ is the damping coefficient of cross-linked polyethylene, with a value of 106 Ns / m. 3 Δz is the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model, υ ztυ represents the velocity of the upper surface of the lower cross-linked polyethylene model. zb The velocity of the lower surface of the upper silicone rubber model.

[0023] Furthermore, the above-mentioned simulation method for harmonic detection of cable joint interface pressure, wherein the simulation of nonlinear ultrasonic detection of cable joint interface pressure on the cable joint pressure model and the acquisition of the spectrum at each probe point on the cable joint pressure model include the following steps: setting at least three probe points on the lower surface of the second layer in the cable joint model; adding probe plotting groups to the set probe points to obtain the echo time-domain signals at each probe point under different interface pressures; using Fast Fourier Transform (FFT) to transform the echo time-domain signals at each probe point into frequency-domain signals to obtain the spectrum at each probe point; and extracting the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum.

[0024] On the other hand, the present invention also proposes a simulation device for harmonic detection of cable joint interface pressure. The device includes: a modeling module for modeling a simulation geometric model of the cable joint and setting an ultrasonic excitation source on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves, thereby obtaining a cable joint model; an interface pressure modeling module for setting the spring stiffness and spring force corresponding to a nonlinear spring damper at the contact interface between the upper and lower layers of the cable joint model, thereby obtaining a cable joint pressure model, and simulating the nonlinear interaction force at the interface of the cable joint through the damping of the nonlinear spring damper; and a simulation solution module for performing nonlinear ultrasonic detection of the cable joint interface pressure model, obtaining the spectrum diagram at each probe point on the cable joint pressure model, and obtaining the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram.

[0025] Furthermore, in the aforementioned simulation device for harmonic detection of cable joint interface pressure, the modeling module includes: a thickness acquisition submodule for acquiring the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable joint; and a modeling submodule for performing an equivalent transformation on the cable joint based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer, establishing a cuboid three-dimensional geometric model corresponding to the cable joint, and setting the material and material parameters for the upper silicone rubber model and the lower cross-linked polyethylene model in the cuboid three-dimensional geometric model; wherein the cuboid three-dimensional geometric model includes an upper silicone rubber model and a lower cross-linked polyethylene model, the thickness of the upper silicone rubber model being adapted to the silicone rubber layer in the cable joint, and the thickness of the lower cross-linked polyethylene model being adapted to the thickness of the cross-linked polyethylene layer in the cable joint; The material parameters include: elastic modulus, density, Poisson's ratio, and damping ratio; the excitation source setting submodule is used to set a piecewise function on the upper surface of the upper silicone rubber model in the cuboid three-dimensional geometric model, and add a specified displacement at the middle position of the upper surface of the upper silicone rubber model as the excitation function to set the ultrasonic excitation source to simulate the emission of ultrasonic waves; the boundary condition setting submodule is used to set the boundary conditions of the cuboid three-dimensional geometric model, setting the two sides of the cuboid three-dimensional geometric model as low-reflection boundaries; the mesh generation submodule is used to establish tetrahedral meshes for the upper silicone rubber model and the lower cross-linked polyethylene model based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene; the calculation setting submodule is used to determine and set the calculation mode of the nonlinear ultrasonic testing cable joint interface pressure simulation as transient calculation.

[0026] Furthermore, in the aforementioned simulation device for detecting harmonic pressure at the cable joint interface, the excitation function F corresponding to the specified displacement from solid mechanics is:

[0027] F=A(1-cos(2*π*f*t / n))*sin(2*π*f*t);

[0028] Where A is the amplitude of the excitation signal, set to 500nm; f is the frequency of the excitation signal, set to 26165Hz; n is the number of periods of the excitation wave, set to 10; and t is the excitation signal time.

[0029] Furthermore, the aforementioned simulation device for detecting harmonic stress at the cable joint interface determines the damping ratio of the corresponding material based on its mass damping and stiffness damping; wherein the damping ratio is determined using the following formula:

[0030]

[0031] Where μ is the damping ratio of the corresponding material; α is the mass damping of the corresponding material; ω is the frequency of the corresponding material; and β is the stiffness damping of the corresponding material.

[0032] Furthermore, in the aforementioned simulation device for harmonic detection of cable joint interface pressure, the interface pressure modeling module includes: a stiffness conversion submodule, used to set the contact interface stiffness at the contact interface between the two insulation layers in the cable joint model to the spring stiffness in the nonlinear spring damper; and a pressure setting submodule, used to set the interface pressure at the contact interface between the two insulation layers in the cable joint model to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

[0033] Furthermore, in the aforementioned simulation device for harmonic detection of cable joint interface pressure, the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers of the interface is calculated using the following formula:

[0034] △F=F st —F dt ;

[0035] Where ΔF is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F represents the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model. dt This represents the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0036] Furthermore, in the aforementioned simulation device for harmonic detection of cable joint interface pressure, the spring force per unit area on the lower surface of the upper silicone rubber model in the cable joint model is calculated using the following formula:

[0037]

[0038] Where a = 4, b = 5, Z0 = 0.1 nm, k1 = 5 × 10¹² N / m 3 k1 = 3 × 10¹² N / m 3 , Δz represents the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0039] The spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model is calculated using the following formula:

[0040]

[0041] Where b = 5, Z0 = 0.1 nm, and γ is the damping coefficient of cross-linked polyethylene, with a value of 106 Ns / m. 3 Δz is the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model, υ ztυ represents the velocity of the upper surface of the lower cross-linked polyethylene model. zb The velocity of the lower surface of the upper silicone rubber model.

[0042] Furthermore, in the aforementioned simulation device for harmonic detection of cable joint interface pressure, the simulation solution module includes: a probe setting submodule, used to set at least three point probes on the lower surface of the second layer in the cable joint model; a time-domain signal acquisition submodule, used to add probe plotting groups to the set point probes to obtain the echo time-domain signals at each point probe under different interface pressures; a spectrum acquisition submodule, used to transform the echo time-domain signals at each point probe into frequency-domain signals using Fast Fourier Transform (FFT) to obtain the spectrum at each point probe; and a harmonic amplitude extraction submodule, used to extract the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum.

[0043] In another aspect, a computer-readable storage medium is provided, the storage medium storing a computer program for performing the methods described in any of the above aspects of the present invention.

[0044] In another aspect, an electronic device is provided, the electronic device comprising: a processor; a memory for storing processor-executable instructions; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0045] This invention provides a simulation method, device, and medium for harmonic detection of interface pressure at cable joints. The simulation method belongs to the three-dimensional simulation method for nonlinear harmonic detection of interface pressure at cable joints. For actual high-voltage cable joints, a simulation geometric model of the cable joint is created, and an ultrasonic excitation source is placed on the upper surface of the first layer of the model to simulate ultrasonic wave emission, thus obtaining a cable joint model. A nonlinear spring damper is then used to model the cable joint model to simulate the nonlinear interaction at the interface of the cable joint. Utilizing the principle of nonlinear harmonic detection, the changes in harmonic characteristics with varying interface pressure are explored in depth, thereby establishing the relationship between the two. This allows for accurate simulation of the state of the cable joint under various interface pressures, fully considering the pressure at the cable joint interface, making the simulation results practically meaningful. A novel nonlinear interface model is used for simulation analysis of cable joint interface pressure detection, demonstrating significant innovation. The model employs nonlinear ultrasonic testing to simulate the interface pressure of cable joints, obtaining spectral data at the probe points. Based on this spectral data, the amplitudes of harmonics and subharmonics under different interface pressures are determined, allowing for the study of the relationship between interface pressure and ultrasonic harmonic amplitudes. This utilizes the principle of nonlinear harmonic detection to delve into the changes in harmonic characteristics as interface pressure varies, establishing a direct relationship between the two. This provides support for further experimental research methods and effectively avoids interference with actual cable joints. It enables rapid and accurate assessment of interface pressure, providing crucial data for optimizing the design of cable joints and helping to improve joint structures to better cope with pressure changes. This addresses the bottleneck and lack of existing experimental research on the relationship between interface pressure and ultrasonic harmonics. Furthermore, this method helps in developing scientific maintenance strategies to ensure safe and reliable power transmission and reduce maintenance costs and power outage losses caused by joint failures.

[0046] Furthermore, this method, device, and medium, by combining nonlinear harmonic theory with three-dimensional simulation, can accurately capture harmonic changes caused by pressure variations, reducing errors and providing scientific support for joint condition assessment. It also avoids the problems of traditional detection methods that damage cable joints, ensuring the integrity and stability of the power system. For design and maintenance, based on simulation information, designers can optimize joint structures, enhancing their tolerance to pressure changes and reducing the probability of failure. Maintenance personnel can customize strategies, rationally schedule cycles and priorities, reduce unnecessary maintenance, lower costs, and improve the economic efficiency of the power system. In terms of efficiency, it can quickly simulate a large number of operating conditions to obtain pressure information, and the method is highly versatile, not limited by joint type, size, or material, demonstrating high application potential and academic value. Attached Figure Description

[0047] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0048] Figure 1 A flowchart illustrating the simulation method for harmonic detection of cable joint interface pressure provided in this embodiment of the invention;

[0049] Figure 2 A detailed flowchart of the simulation method for harmonic detection cable joint interface pressure provided in this embodiment of the invention;

[0050] Figure 3 This is a schematic diagram of the structure of a cable connector model provided in an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram of the signal transmission and reception arrangement in the cable connector model provided in the embodiment of the present invention;

[0052] Figure 5 This is a schematic diagram of the structure of the cable joint pressure model provided in an embodiment of the present invention;

[0053] Figure 6 The echo time-domain signal diagram at one of the receiving points, namely the point probe, when the interface pressure is 0, is provided in an embodiment of the present invention.

[0054] Figure 7 A spectrum diagram of one of the receiving points when the interface pressure is 0, provided in an embodiment of the present invention;

[0055] Figure 8 This is an echo time-domain signal diagram at another receiving point when the interface pressure is 0, provided in an embodiment of the present invention.

[0056] Figure 9 A spectrum diagram at another receiving point when the interface pressure is 0, provided in an embodiment of the present invention;

[0057] Figure 10 A flowchart of the modeling steps provided in an embodiment of the present invention;

[0058] Figure 11 A flowchart illustrating the interface pressure modeling steps provided in an embodiment of the present invention;

[0059] Figure 12 A flowchart illustrating the simulation solution steps provided in this embodiment of the invention;

[0060] Figure 13 A structural block diagram of a simulation device for detecting harmonic cable joint interface pressure provided in an embodiment of the present invention;

[0061] Figure 14 This is a structural block diagram of the modeling module provided in an embodiment of the present invention;

[0062] Figure 15 This is a structural block diagram of the interface pressure modeling module provided in an embodiment of the present invention;

[0063] Figure 16 This is a structural block diagram of the simulation solving module provided in an embodiment of the present invention;

[0064] Figure 17 This is a structural block diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0065] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0066] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0067] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0068] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0069] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0070] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0071] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0072] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0073] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0074] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0075] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0076] The embodiments of this invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate together with a wide range of other general-purpose or special-purpose computing system environments or configurations. Well-known examples of terminal devices, computing systems, environments, and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, and servers include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments including any of the above systems, etc.

[0077] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in distributed cloud computing environments, where tasks are executed by remote processing devices linked through communication networks. In distributed cloud computing environments, program modules can reside on local or remote computing system storage media, including storage devices.

[0078] Method Implementation Examples:

[0079] See Figures 1 to 2 The figure illustrates a preferred flow of the simulation method for harmonic detection cable joint interface pressure provided by an embodiment of the present invention. As shown in the figure, the simulation method includes the following steps:

[0080] Modeling step S1 involves creating a simulation geometric model of the cable joint and setting an ultrasonic excitation source on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves, thus obtaining the cable joint model.

[0081] Specifically, based on the solid structure of the cable joint, the finite element software Abaqus is used to model the simulation geometry. By adding a specified displacement from solid mechanics to the upper surface of the first layer of the model, a segmented ultrasonic excitation source is set. That is, the specified displacement from solid mechanics added to the upper surface of the first layer of the model serves as the excitation function. This allows for the setting of multiple ultrasonic excitation sources at different locations on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves, thus obtaining the cable joint model, such as... Figure 3 As shown. The location of the ultrasonic excitation source can be... Figure 4 The signal transmission point is shown.

[0082] In the interface pressure modeling step S2, at the upper and lower contact interfaces of the cable joint model, the contact interface stiffness and interface pressure are set to match the nonlinear spring damper to obtain the cable joint pressure model, so as to simulate the nonlinear interaction force at the interface of the cable intermediate joint through the damping of the nonlinear spring damper.

[0083] Specifically, in the cable joint model, at the contact interface between the two insulation layers—the upper silicone rubber model and the lower cross-linked polyethylene model—a contact interface stiffness and interface pressure matching the nonlinear spring damper can be set. This is equivalent to establishing a nonlinear spring damper model at the interface. In other words, modeling is done using a nonlinear spring damper to simulate the nonlinear interaction forces at the interface, resulting in a cable joint pressure model incorporating nonlinear harmonics. Figure 5 As shown. In other words, by utilizing the principle of nonlinear harmonic detection, we can delve into the changes in harmonic characteristics when the interface pressure changes, thereby establishing the relationship between the two and accurately simulating the state of cable joints under various interface pressures.

[0084] In simulation solution step S3, a nonlinear ultrasonic testing of the cable joint interface pressure model is performed to simulate the pressure of the cable joint interface and obtain the spectrum diagram at each probe point on the cable joint pressure model. Based on the spectrum diagram, the amplitude of harmonics and subharmonics under different interface pressures is obtained.

[0085] Specifically, multiple point probes are set on the lower surface of the lower layer of the cable joint model, i.e., the lower surface of the lower cross-linked polyethylene model. Each point probe can be located directly below a different ultrasonic excitation source. This allows for nonlinear ultrasonic testing of the cable joint interface pressure model, simulating the interface pressure, and obtaining the spectral diagrams at each point probe. For example, the spectral diagram at the point probe when the interface pressure is 0 can be obtained. Figure 7 and Figure 9As shown, this method utilizes nonlinear ultrasound to detect the interface pressure of cable joints. The ultrasonic probe used in the testing is a single transmitter and receiver type. The amplitude of harmonics and subharmonics under different interface pressures is obtained based on the spectrum diagram, enabling rapid and accurate assessment of the interface pressure. This provides crucial data for the design optimization of cable joints, helping to improve the joint structure to better cope with pressure changes. The location of the point probe can be... Figure 4 The signal receiving point is shown; there are multiple point probes so that the echo waveforms of multiple points can be extracted during ultrasonic testing to reduce errors.

[0086] See Figure 10 This is a flowchart of the modeling steps provided in an embodiment of the present invention. As shown in the figure, the modeling step S1 includes the following sub-steps:

[0087] Thickness acquisition sub-step S11: Acquire the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint.

[0088] Specifically, the thickness of the silicone rubber joint and the cross-linked polyethylene (XLPE) of the cable body in the actual cable intermediate structure is measured to obtain the thickness of the XLPE layer and silicone rubber layer in the cable intermediate joint. The cable intermediate joint comprises a three-layer structure, from the inside out: a copper or aluminum core, XLPE, and silicone rubber, with XLPE and silicone rubber serving as insulation layers.

[0089] Modeling sub-step S12 involves performing an equivalent transformation on the cable joint based on the thicknesses of the cross-linked polyethylene layer and the silicone rubber layer, thus establishing a corresponding cuboid three-dimensional geometric model of the cable joint. Figure 3 As shown, the material settings and material parameters of the upper silicone rubber model and the lower cross-linked polyethylene model in the three-dimensional geometric model of the cuboid are set. The three-dimensional geometric model of the cuboid includes the upper silicone rubber model and the lower cross-linked polyethylene model. The thickness of the upper silicone rubber model is adapted to the silicone rubber layer in the cable intermediate joint, and the thickness of the lower cross-linked polyethylene model is adapted to the thickness of the cross-linked polyethylene layer in the cable intermediate joint. The material parameters include: elastic modulus, density, and Poisson's ratio.

[0090] Specifically, firstly, the cable joint is transformed into an equivalent model, with the cross-linked polyethylene (XLPE) layer and silicone rubber layer in the joint represented as cuboid models with matching thicknesses. Based on the thicknesses of the XLPE and silicone rubber layers obtained in sub-step S11, upper silicone rubber models and lower XLPE models with corresponding thicknesses are created using the finite element software Abaqus. These models are then stacked to form a unified model. Next, material settings are applied to the upper silicone rubber and lower XLPE models, with the materials set for silicone rubber and XLPE respectively. Finally, material parameters are set for the corresponding geometric model parts, namely the upper silicone rubber model and the lower XLPE model. These parameters include elastic modulus E, density ρ, and Poisson's ratio σ, and may also include damping ratio. Based on the mass damping and stiffness damping of the corresponding materials, the damping ratio is determined; the damping ratio μ can be determined using the following formula:

[0091]

[0092] Where μ is the damping ratio of the corresponding material; α is the mass damping of the corresponding material; ω is the frequency of the corresponding material; and β is the stiffness damping of the corresponding material.

[0093] In the excitation source setting sub-step S13, a piecewise function is set for the upper surface of the upper silicone rubber model in the cuboid three-dimensional geometric model, and a specified displacement is added at the middle position of the upper surface of the upper silicone rubber model as the excitation function to set the ultrasonic excitation source to simulate the emission of ultrasonic waves.

[0094] Specifically, ultrasonic wave emission is simulated by adding a specified displacement from solid mechanics to the upper surface of the first layer of the model, i.e., the upper silicone rubber model. The corresponding excitation function is:

[0095] F=A(1-cos(2*π*f*t / n))*sin(2*π*f*t);

[0096] Where A is the amplitude of the excitation signal, set to 500nm; f is the frequency of the excitation signal, set to 26165Hz; n is the number of periods of the excitation wave, set to 10; and t is the excitation signal time.

[0097] Boundary condition setting sub-step S14 sets the boundary conditions for the cuboid 3D geometric model, setting the two sides of the cuboid 3D geometric model as low-reflection boundaries.

[0098] Specifically, the boundary conditions of the geometric model are set according to the actual cable joint, and low-reflection boundaries are set on both sides of the geometry.

[0099] In the mesh generation sub-step S15, tetrahedral meshes are created for the upper silicone rubber model and the lower cross-linked polyethylene model based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene, respectively.

[0100] Specifically, a tetrahedral mesh is established. Based on the different ultrasonic velocities of the materials corresponding to different domains, the mesh size varies for each domain, typically taking 1 / 12 of the wavelength λ, where λ is:

[0101]

[0102] Where c is the ultrasonic wave velocity and f is the excitation frequency, set to 26165Hz.

[0103] In the calculation setting sub-step S16, the calculation mode for the simulation of nonlinear ultrasonic testing cable joint interface pressure is determined and set to transient calculation.

[0104] Specifically, transient calculations are used in the simulation of interface pressure for nonlinear ultrasonic testing of cable joints.

[0105] See Figure 11 This is a flowchart of the interface stress modeling step provided in an embodiment of the present invention. As shown in the figure, the interface stress modeling step S2 includes the following sub-steps:

[0106] In stiffness conversion sub-step S21, the contact interface stiffness at the contact interface between the two insulation layers in the cable joint model is set to the spring stiffness in the nonlinear spring damper.

[0107] Specifically, in the cable joint model, the contact interface stiffness at the contact interface between the two insulation layers is converted into the spring stiffness in the nonlinear spring damper.

[0108] In the pressure setting sub-step S22, the interface pressure at the contact interface between the two insulation layers in the cable joint model is set to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

[0109] Specifically, by adjusting the force F applied between the upper and lower materials at the interface. st F dt The difference F st —F dt Set different interface pressures, such as Figure 5 As shown, the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface can be calculated using the following formula:

[0110] △F=F st —F dt ;

[0111] Where ΔF is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F represents the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model. dt This represents the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0112] In this embodiment, the spring force per unit area on the lower surface of the upper silicone rubber model in the cable joint model is calculated using the following formula:

[0113]

[0114] Where a = 4, b = 5, Z0 = 0.1 nm, k1 = 5 × 10¹² N / m 3 k1 = 3 × 10¹² N / m 3 , Δz represents the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0115] The spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model is calculated using the following formula:

[0116]

[0117] Where b = 5, Z0 = 0.1 nm, and γ is the damping coefficient of cross-linked polyethylene, with a value of 106 Ns / m. 3 Δz is the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model, υ zt υ represents the velocity of the upper surface of the lower cross-linked polyethylene model. zb The velocity of the lower surface of the upper silicone rubber model.

[0118] See Figure 12 This is a flowchart of the simulation solution steps provided in this embodiment of the invention. As shown in the figure, simulation solution step S3 includes the following sub-steps:

[0119] In probe setting sub-step S31, at least three point probes are set on the lower surface of the second layer in the cable joint model.

[0120] Specifically, five point probes were placed on the lower surface of the second layer of the model material, namely the lower cross-linked polyethylene model. The point probes were all located directly below different ultrasonic excitation sources.

[0121] In the time-domain signal acquisition sub-step S32, a probe drawing group is added to the set point probes to obtain the echo time-domain signals at each point probe under different interface pressures.

[0122] Specifically, a probe plotting group is added to the results dataset to obtain the time-domain signal of the echo amplitude at different points under different interface pressures. Figure 6 and Figure 8 As shown.

[0123] In the spectrum acquisition sub-step S33, the echo time-domain signal at each probe point is transformed into a frequency-domain signal using Fast Fourier Transform to obtain the spectrum at each probe point.

[0124] Specifically, the Fast Fourier Transform (FFT) is used to transform the echo time-domain signal at different receiving points into a frequency-domain signal, thereby obtaining the spectrum at different receiving points, such as... Figure 7 and Figure 9 As shown.

[0125] The harmonic amplitude extraction sub-step S34 extracts the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram.

[0126] Specifically, the amplitudes of harmonics and subharmonics under different interface pressures are extracted based on the spectrum diagram.

[0127] In this embodiment, in the modeling step S1, the surface with higher stiffness is set as the master surface, while the surface with lower stiffness is selected as the slave surface. That is, in the cable joint model, the lower surface of the first layer and the upper surface of the second layer are set as the master surface, while the surface with lower stiffness is selected as the slave surface.

[0128] In summary, the simulation method for harmonic detection of cable joint interface pressure provided in this embodiment belongs to the three-dimensional simulation method for nonlinear harmonic detection of cable intermediate joint interface pressure. For actual high-voltage cable intermediate joints, a simulation geometric model of the cable intermediate joint is created, and an ultrasonic excitation source is placed on the upper surface of the first layer of the model to simulate ultrasonic wave emission, thus obtaining the cable joint model. Furthermore, a nonlinear spring damper is used to model the cable joint model to simulate the nonlinear interaction at the cable intermediate joint interface. Utilizing the principle of nonlinear harmonic detection, the changes in harmonic characteristics when interface pressure changes are explored in depth, thereby establishing the relationship between the two. This allows for accurate simulation of the state of the cable intermediate joint under various interface pressures, fully considering the pressure at the cable intermediate joint interface, making the simulation results practically meaningful. Moreover, by establishing a new interface... This innovative approach utilizes a nonlinear model to simulate and analyze the interface pressure detection of cable joints. It employs nonlinear ultrasonic testing to simulate the interface pressure of cable joints, obtaining spectral data at the probe points. Based on this spectral data, the amplitudes of harmonics and subharmonics under different interface pressures are determined, allowing for the study of the relationship between interface pressure and ultrasonic harmonic amplitudes. Specifically, by applying the principle of nonlinear harmonic detection, this method delves into the changes in harmonic characteristics as interface pressure changes, establishing a direct relationship between the two. This provides support for further experimental research methods and effectively avoids interference with actual cable joints. It enables rapid and accurate assessment of interface pressure, providing crucial data for optimizing the design of cable joints and helping to improve joint structures to better cope with pressure variations. This addresses the bottleneck and lack of existing experimental research on the relationship between interface pressure and ultrasonic harmonics. Furthermore, this method helps in developing scientific maintenance strategies to ensure safe and reliable power transmission and reduce maintenance costs and power outage losses caused by joint failures.

[0129] Furthermore, this method, by combining nonlinear harmonic theory with 3D simulation, can accurately capture harmonic changes caused by pressure variations, reducing errors and providing scientific support for joint condition assessment. It also avoids the problems of traditional detection methods that damage cable joints, ensuring the integrity and stability of the power system. For design and maintenance, based on simulation information, designers can optimize joint structures, enhancing their tolerance to pressure changes and reducing the probability of failure. Maintenance personnel can customize strategies, rationally schedule cycles and priorities, reduce unnecessary maintenance, lower costs, and improve the economic efficiency of the power system. In terms of efficiency, it can quickly simulate a large number of operating conditions to obtain pressure information, and the method is highly versatile, not limited by joint type, size, or material, demonstrating high application potential and academic value.

[0130] Device Example:

[0131] See Figure 13This is a structural block diagram of the simulation device for harmonic detection of cable joint interface pressure provided in this embodiment of the invention. As shown in the figure, the device further includes: a modeling module 100, an interface pressure modeling module 200, and a simulation solving module 300; wherein, the modeling module 100 is used to model the simulation geometry of the cable joint and set an ultrasonic excitation source on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves, thereby obtaining a cable joint model; the interface pressure modeling module 200 is used to set the contact interface stiffness and interface pressure matching the nonlinear spring damper at the contact interface of the upper and lower layers of the cable joint model, thereby obtaining a cable joint pressure model, so as to simulate the nonlinear interaction force at the interface of the cable joint through the damping of the nonlinear spring damper; the simulation solving module 300 is used to perform nonlinear ultrasonic detection of the cable joint interface pressure simulation on the cable joint pressure model, obtain the spectrum diagram at each probe point on the cable joint pressure model, and obtain the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram.

[0132] See Figure 14 This is a structural block diagram of the modeling module provided in this embodiment of the invention. As shown in the figure, the modeling module 100 includes: a thickness acquisition submodule 110, a modeling submodule 120, an excitation source setting submodule 130, a boundary condition setting submodule 140, a mesh generation submodule 150, and a calculation setting submodule 160; wherein, the thickness acquisition submodule 110 is used to acquire the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable joint; the modeling submodule 120 is used to perform an equivalent transformation on the cable joint based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable joint, establish a cuboid three-dimensional geometric model corresponding to the cable joint, and set the material and material parameters of the upper silicone rubber model and the lower cross-linked polyethylene model in the cuboid three-dimensional geometric model; wherein, the cuboid three-dimensional geometric model includes an upper silicone rubber model and a lower cross-linked polyethylene model, the thickness of the upper silicone rubber model is adapted to the silicone rubber layer in the cable joint, and the thickness of the lower cross-linked polyethylene model is... The thickness is adapted to the thickness of the cross-linked polyethylene layer in the cable joint; material parameters include: elastic modulus, density, Poisson's ratio, and damping ratio; excitation source setting submodule 130 is used to set a piecewise function on the upper surface of the upper silicone rubber model in the cuboid three-dimensional geometric model, and add a specified displacement at the middle position of the upper surface of the upper silicone rubber model as the excitation function to set the ultrasonic excitation source to simulate the emission of ultrasonic waves; boundary condition setting submodule 140 is used to set the boundary conditions of the cuboid three-dimensional geometric model, and set the two sides of the cuboid three-dimensional geometric model as low reflection boundaries; mesh generation submodule 150 is used to establish tetrahedral meshes for the upper silicone rubber model and the lower cross-linked polyethylene model based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene; calculation setting submodule 160 is used to determine and set the calculation mode of the nonlinear ultrasonic testing cable joint interface pressure simulation as transient calculation.

[0133] Preferably, the excitation function F corresponding to the specified displacement in solid mechanics is:

[0134] F=A(1-cos(2*π*f*t / n))*sin(2*π*f*t);

[0135] Where A is the amplitude of the excitation signal, set to 500nm; f is the frequency of the excitation signal, set to 26165Hz; n is the number of periods of the excitation wave, set to 10; and t is the excitation signal time.

[0136] Preferably, the damping ratio of the corresponding material is determined based on its mass damping and stiffness damping; wherein the damping ratio is determined using the following formula:

[0137]

[0138] Where μ is the damping ratio of the corresponding material; α is the mass damping of the corresponding material; ω is the frequency of the corresponding material; and β is the stiffness damping of the corresponding material.

[0139] See Figure 15 This is a structural block diagram of the interface pressure modeling module provided in this embodiment of the invention. As shown in the figure, the interface pressure modeling module 200 includes: a stiffness conversion submodule 210 and a pressure setting submodule 220; wherein, the stiffness conversion submodule 210 is used to set the contact interface stiffness at the contact interface between the two insulation layers in the cable joint model to the spring stiffness in the nonlinear spring damper; the pressure setting submodule 220 is used to set the interface pressure at the contact interface between the two insulation layers in the cable joint model to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers of the interface, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

[0140] Preferably, the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface is calculated using the following formula:

[0141] △F=F st —F dt ;

[0142] Where ΔF is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F represents the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model. dt This represents the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0143] Preferably, the spring force per unit area on the lower surface of the upper silicone rubber model in the cable joint model is calculated using the following formula:

[0144]

[0145] Where a = 4, b = 5, Z0 = 0.1 nm, k1 = 5 × 10¹² N / m 3 k1 = 3 × 10¹² N / m 3 , Δz represents the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model in the cable joint model.

[0146] The spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model is calculated using the following formula:

[0147]

[0148] Where b = 5, Z0 = 0.1 nm, and γ is the damping coefficient of cross-linked polyethylene, with a value of 106 Ns / m. 3 Δz is the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model, υ zt υ represents the velocity of the upper surface of the lower cross-linked polyethylene model. zb The velocity of the lower surface of the upper silicone rubber model.

[0149] See Figure 16 This is a structural block diagram of the simulation solution module provided in this embodiment of the invention. As shown in the figure, the simulation solution module 300 includes: a probe setting submodule 310, a time-domain signal acquisition submodule 320, a spectrum acquisition submodule 330, and a harmonic amplitude extraction submodule 340; wherein, the probe setting submodule 310 is used to set at least three point probes on the lower surface of the second layer in the cable joint model; the time-domain signal acquisition submodule 320 is used to add probe drawing groups to the set point probes to obtain the echo time-domain signals at each point probe under different interface pressures; the spectrum acquisition submodule 330 is used to transform the echo time-domain signals at each point probe into frequency-domain signals using Fast Fourier Transform (FFT) to obtain the spectrum at each point probe; the harmonic amplitude extraction submodule 340 is used to extract the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum.

[0150] Electronic device example:

[0151] See Figure 17 This is a structural block diagram of the electronic device provided in an embodiment of the present invention. For example... Figure 17 As shown, the electronic device 400 includes one or more processors 41 and memory 42.

[0152] The processor 41 may be a central processing unit (CPU) or other form of processing unit with data processing and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0153] The memory 42 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 41 may execute the program instructions to implement the methods of the software programs described in the various embodiments of the present invention above, and / or other desired functions. In one example, the electronic device may also include an input device 43 and an output device 44, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0154] In addition, the input device 43 may also include, for example, a keyboard, a mouse, etc.

[0155] The output device 44 can output various information to the outside. The output device 44 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0156] Of course, for the sake of simplicity, Figure 17 Only some of the components of this electronic device relevant to the present invention are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0157] Examples of computer program products and computer-readable storage media:

[0158] In addition to the methods and apparatus described above, embodiments of the present invention may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0159] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of the present invention. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0160] Furthermore, embodiments of the present invention may also be computer-readable storage media storing computer program instructions thereon, which, when executed by a processor, cause the processor to perform the steps of the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0161] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0162] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0163] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0164] The block diagrams of devices, systems, devices, and systems involved in this invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, systems, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0165] The methods and systems of the present invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of the present invention are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, the present invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers recording media storing programs for performing the methods according to the present invention.

[0166] It should also be noted that in the systems, apparatus, and methods of the present invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalents of the present invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0167] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A simulation method for harmonic detection of interface pressure at cable joints, characterized in that, Includes the following steps: A simulation geometric model of the cable joint is created, and an ultrasonic excitation source is set on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves, thus obtaining the cable joint model. At the upper and lower contact interfaces of the cable joint model, the contact interface stiffness and interface pressure are set to match the nonlinear spring damper to obtain the cable joint pressure model, so as to simulate the nonlinear interaction pressure at the interface of the cable joint through the damping of the nonlinear spring damper. Nonlinear ultrasonic testing was performed on the cable joint pressure model to simulate the interface pressure of the cable joint and obtain the spectrum at each probe point on the cable joint pressure model. Based on the spectrum, the amplitude of harmonics and subharmonics under different interface pressures was obtained. The process of modeling the simulation geometry of the cable joint and setting an ultrasonic excitation source on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves includes the following sub-steps: Obtain the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable joint; Based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable joint, an equivalent transformation is performed on the cable joint to establish a corresponding cuboid three-dimensional geometric model. Material settings and parameter settings are then applied to the upper silicone rubber model and the lower cross-linked polyethylene model within the cuboid three-dimensional geometric model. The cuboid three-dimensional geometric model includes an upper silicone rubber model and a lower cross-linked polyethylene model. The thickness of the upper silicone rubber model is adapted to the thickness of the silicone rubber layer in the cable joint, and the thickness of the lower cross-linked polyethylene model is adapted to the thickness of the cross-linked polyethylene layer in the cable joint. The material parameters include: elastic modulus, density, Poisson's ratio, and damping ratio. A piecewise function is set on the upper surface of the upper silicone rubber model in the three-dimensional geometric model of the cuboid, and a specified displacement is added at the middle position of the upper surface of the upper silicone rubber model as an excitation function to set an ultrasonic excitation source to simulate the emission of ultrasonic waves. Set the boundary conditions of the cuboid three-dimensional geometric model, and set the two sides of the cuboid three-dimensional geometric model as low-reflection boundaries; Based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene, tetrahedral meshes were established for the upper silicone rubber model and the lower cross-linked polyethylene model, respectively. The calculation mode for the simulation of interface pressure of nonlinear ultrasonic testing cable joints was determined and set to transient calculation.

2. The simulation method for harmonic detection cable joint interface pressure according to claim 1, characterized in that, The excitation function F corresponding to the added specified displacement is: ； Where A is the amplitude of the excitation signal, set to 500nm; f is the frequency of the excitation signal, set to 26165Hz; n is the number of periods of the excitation wave, set to 10; and t is the excitation signal time.

3. The simulation method for harmonic detection cable joint interface pressure according to claim 1, characterized in that, Based on the mass damping and stiffness damping of the corresponding material, the damping ratio of the corresponding material is determined; wherein, the damping ratio is determined using the following formula: ； in, This refers to the damping ratio of the corresponding material; For the mass damping of the corresponding material; For the corresponding material frequency; This represents the stiffness and damping of the corresponding material.

4. The simulation method for harmonic detection cable joint interface pressure according to any one of claims 1 to 3, characterized in that, The process of setting contact interface stiffness and interface pressure at the upper and lower contact interfaces of the cable joint model to match the nonlinear spring damper, thereby obtaining the cable joint pressure model, includes the following steps: In the cable joint model, the contact interface stiffness at the contact interface between the two insulation layers is set to the spring stiffness in a nonlinear spring damper. In the cable joint model, the interfacial pressure between the two insulation layers is set as the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

5. The simulation method for harmonic detection cable joint interface pressure according to claim 4, characterized in that, The difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface is calculated using the following formula: △F= F st —F dt ; Where ΔF is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F represents the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model. dt This represents the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model.

6. The simulation method for harmonic detection cable joint interface pressure according to claim 5, characterized in that, The spring force per unit area on the lower surface of the upper silicone rubber model in the cable joint model is calculated using the following formula: ； Where a=4, b=5, Z0=0.1nm, k1=5×10¹²N / m 3 k2 = 3 × 10¹² N / m 3 , , The displacement between the lower surface of the upper silicone rubber model in the cable joint model and the upper surface of the lower cross-linked polyethylene model in the cable joint model; The spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model is calculated using the following formula: ； Where b=5, Z0=0.1nm, The damping coefficient of cross-linked polyethylene is 106 Ns / m. 3 , This represents the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model. The velocity of the upper surface of the lower cross-linked polyethylene model. The velocity of the lower surface of the upper silicone rubber model.

7. The simulation method for harmonic detection cable joint interface pressure according to any one of claims 1 to 3, characterized in that, The nonlinear ultrasonic testing of the cable joint interface pressure model to simulate the pressure of the cable joint and obtain the spectrum at each probe point on the cable joint pressure model includes the following steps: At least three point probes are provided on the lower surface of the second layer in the cable joint model; Add a probe plotting group to the set point probes to obtain the echo time domain signal at each point probe under different interface pressures; The echo time-domain signal at each probe point is transformed into a frequency-domain signal using Fast Fourier Transform (FFT) to obtain the spectrum at each probe point. The amplitudes of harmonics and subharmonics under different interface pressures are extracted from the spectrum.

8. A simulation device for detecting harmonic stress at the interface of a cable joint, characterized in that, include: The model building module is used to model the simulation geometry of the cable joint and to set an ultrasonic excitation source on the upper surface of the first layer of the model to simulate the emission of ultrasonic waves, thus obtaining the cable joint model. The interface pressure modeling module is used to set the contact interface stiffness and interface pressure at the upper and lower contact interfaces of the cable joint model to match the nonlinear spring damper, so as to obtain the cable joint pressure model and simulate the nonlinear interaction force at the interface of the cable intermediate joint through the damping of the nonlinear spring damper. The simulation solution module is used to perform nonlinear ultrasonic testing of the cable joint interface pressure model, obtain the spectrum at each probe point on the cable joint pressure model, and obtain the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum. The model building module includes: The thickness acquisition submodule is used to acquire the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint; The modeling submodule is used to perform an equivalent transformation on the cable joint based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable joint, establish a cuboid three-dimensional geometric model corresponding to the cable joint, and set the material and material parameters for the upper silicone rubber model and the lower cross-linked polyethylene model in the cuboid three-dimensional geometric model. The cuboid three-dimensional geometric model includes an upper silicone rubber model and a lower cross-linked polyethylene model. The thickness of the upper silicone rubber model is adapted to the thickness of the silicone rubber layer in the cable joint, and the thickness of the lower cross-linked polyethylene model is adapted to the thickness of the cross-linked polyethylene layer in the cable joint. The material parameters include: elastic modulus, density, Poisson's ratio, and damping ratio. The excitation source setting submodule is used to set a piecewise function on the upper surface of the upper silicone rubber model in the cuboid three-dimensional geometric model, and to add a specified displacement at the middle position of the upper surface of the upper silicone rubber model as the excitation function, so as to set the ultrasonic excitation source to simulate the emission of ultrasonic waves. The boundary condition setting submodule is used to set the boundary conditions of the cuboid three-dimensional geometric model, setting the two sides of the cuboid three-dimensional geometric model as low-reflection boundaries; The mesh generation submodule is used to create tetrahedral meshes for the upper silicone rubber model and the lower cross-linked polyethylene model based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene. The calculation settings submodule is used to determine and set the calculation mode for the simulation of interface pressure of nonlinear ultrasonic testing cable joints to transient calculation.

9. The simulation device for harmonic detection of cable joint interface pressure according to claim 8, characterized in that, The excitation function F corresponding to the added specified displacement is: ； Where A is the amplitude of the excitation signal, set to 500nm; f is the frequency of the excitation signal, set to 26165Hz; n is the number of periods of the excitation wave, set to 10; and t is the excitation signal time.

10. The simulation device for harmonic detection of cable joint interface pressure according to claim 8, characterized in that, Based on the mass damping and stiffness damping of the corresponding material, the damping ratio of the corresponding material is determined; wherein, the damping ratio is determined using the following formula: ； in, This refers to the damping ratio of the corresponding material; For the mass damping of the corresponding material; For the corresponding material frequency; This represents the stiffness and damping of the corresponding material.

11. The simulation device for harmonic detection of cable joint interface pressure according to any one of claims 8 to 10, characterized in that, The interface pressure modeling module includes: The stiffness conversion submodule is used to set the contact interface stiffness at the contact interface between the two insulation layers in the cable joint model to the spring stiffness in the nonlinear spring damper. The pressure setting submodule is used to set the interface pressure at the contact interface between the two insulation layers in the cable joint model to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulation layers, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

12. The simulation device for harmonic detection of cable joint interface pressure according to claim 11, characterized in that, The difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface is calculated using the following formula: △F= F st —F dt ; Where ΔF is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F represents the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model. dt This represents the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model.

13. The simulation device for harmonic detection of cable joint interface pressure according to claim 12, characterized in that, The spring force per unit area on the lower surface of the upper silicone rubber model in the cable joint model is calculated using the following formula: ； Where a=4, b=5, Z0=0.1nm, k1=5×10¹²N / m 3 k2 = 3 × 10¹² N / m 3 , , The displacement between the lower surface of the upper silicone rubber model in the cable joint model and the upper surface of the lower cross-linked polyethylene model in the cable joint model; The spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable joint model is calculated using the following formula: ； Where b=5, Z0=0.1nm, The damping coefficient of cross-linked polyethylene is 106 Ns / m. 3 , This represents the displacement between the lower surface of the upper silicone rubber model and the upper surface of the lower cross-linked polyethylene model. The velocity of the upper surface of the lower cross-linked polyethylene model. The velocity of the lower surface of the upper silicone rubber model.

14. The simulation device for harmonic detection of cable joint interface pressure according to any one of claims 8 to 10, characterized in that, The simulation solution module includes: The probe setting submodule is used to set at least three point probes on the lower surface of the second layer in the cable joint model. The time-domain signal acquisition submodule is used to add probe drawing groups to the set point probes and obtain the echo time-domain signals at each point probe under different interface pressures. The spectrum acquisition submodule is used to transform the echo time-domain signal at each probe point into a frequency-domain signal using Fast Fourier Transform (FFT) to acquire the spectrum at each probe point. The harmonic amplitude extraction submodule is used to extract the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram.

15. A computer-readable storage medium, characterized in that, The storage medium stores a computer program for performing the method described in any one of claims 1 to 7.

16. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1 to 7.

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