Simulation method and device for harmonic detection of interface pressure of cable joint, and medium

Abstract

The invention provides a simulation method and device for detecting interface pressure of a cable joint through harmonic waves and a medium. The method comprises the following steps: modeling a simulation geometric model for the cable intermediate joint, and setting an ultrasonic excitation source; modeling through a nonlinear spring damper to obtain a cable joint pressure model; and performing nonlinear ultrasonic detection cable joint interface pressure simulation on the cable joint pressure model to obtain a spectrogram at each point probe. According to the invention, on a cable joint model, modeling is carried out through a nonlinear spring damper, nonlinear interaction at a cable intermediate joint interface is simulated, a nonlinear harmonic detection principle is utilized, and the change of harmonic characteristics when the interface pressure changes is deeply explored, so that the relationship between the two is established; the states of the cable intermediate joint under various interface pressures are accurately simulated, the interface pressure of the cable intermediate joint is fully considered, and simulation analysis is performed on the interface pressure detection of the cable joint by establishing a new interface nonlinear model.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment state detection, and in particular to a simulation method, device and medium for harmonic detection of cable joint interface pressure. Background Art

[0002] As the domestic urbanization process continues to deepen, the scale of cable equipment in urban power grids continues to rise. According to statistics, 70% of cable failures are caused by cable accessory failures, except for external force damage. The silicone rubber-cross-linked polyethylene (XLPE) composite interface between the cable accessories and the cable body has concentrated electric field stress, causing local discharge and insulation breakdown, making the cable accessories a high-incidence part of the cable line failure. In other words, in the power system, the interface pressure of the cable intermediate joint has a significant impact on its performance and safety.

[0003] Traditional detection methods have shortcomings, either destroying the joint structure or failing to accurately reflect the real pressure. At present, few researchers in the field of 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 interface 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, so as to study the relationship between interface pressure and ultrasonic harmonic amplitude, provide support for further experimental research methods, and aim to solve the bottleneck problem of the existing experimental research on the relationship between interface pressure and ultrasonic harmonics.

[0005] On the one hand, the present invention proposes a simulation method for harmonic detection of cable joint interface pressure, which method includes the following steps: modeling a simulation geometric model of a cable intermediate 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, so as to obtain a cable joint model; setting spring stiffness and spring force at the contact interface of the upper and lower layers of the cable joint model to obtain a cable joint pressure model, so as to simulate the nonlinear interaction force at the interface of the cable intermediate joint through the damping of a nonlinear spring damper; performing nonlinear ultrasonic detection of the cable joint interface pressure simulation on the cable joint pressure model, and obtaining a frequency spectrum at each point probe on the cable joint pressure model, so as to obtain the amplitude of harmonics and subharmonics under different interface pressures based on the frequency spectrum.

[0006] Furthermore, the above-mentioned simulation method for harmonic detection of cable joint interface pressure, the modeling of the simulation geometric model of the cable intermediate 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: 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 rectangular three-dimensional geometric model corresponding to the cable intermediate joint, and setting materials and material parameters for the upper silicone rubber model and the lower cross-linked polyethylene model in the rectangular three-dimensional geometric model; wherein the rectangular 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 intermediate joint, and the lower cross-linked polyethylene model is adapted to the silicone rubber layer in the cable intermediate joint. The thickness of the cross-linked polyethylene model is adapted to the thickness of the cross-linked polyethylene layer in the intermediate joint of the cable; the material parameters include: elastic modulus, density, Poisson's ratio and damping ratio; a piecewise function is set for the upper surface of the upper silicone rubber model in the rectangular 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 an ultrasonic excitation source to simulate the emission of ultrasonic waves; the boundary conditions of the rectangular three-dimensional geometric model are set, and the two sides of the rectangular 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; a calculation setting sub-step is performed to determine and set the calculation mode of the nonlinear ultrasonic detection cable joint interface pressure simulation to transient calculation.

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

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

[0009] Among them, A is the excitation signal amplitude, which is set to 500nm; f is the excitation signal frequency, which is set to 26165Hz; n is the number of cycles of the excitation wave, which is 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] Among them, 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; β is the stiffness damping of the corresponding material.

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

[0014] Furthermore, in the above-mentioned simulation method for harmonic detection of cable joint interface pressure, 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:

[0015] △F=F st —F dt ;

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

[0017] Furthermore, in the above-mentioned simulation method for harmonic detection of cable joint interface pressure, the spring force per unit area of ​​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=3×1012N / m 3 , Δz is 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;

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

[0021]

[0022] Where b = 5, Z0 = 0.1 nm, γ is the damping coefficient of cross-linked polyethylene, which is 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 ztis the velocity of the upper surface of the lower cross-linked polyethylene model, υ zb is 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, the cable joint pressure model is subjected to nonlinear ultrasonic detection of cable joint interface pressure simulation, and the frequency spectrum diagram at each point probe on the cable joint pressure model is obtained, including the following steps: at least three point probes are set on the lower surface of the second layer in the cable joint model; a probe drawing group is added 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 point probe is transformed into a frequency domain signal by using fast Fourier transform (FFT) to obtain the frequency spectrum diagram at each point probe; and the amplitude of harmonics and subharmonics under different interface pressures is extracted according to the frequency spectrum diagram.

[0024] On the other hand, the present invention also proposes a simulation device for harmonic detection of cable joint interface pressure, which includes: a modeling module, which is used to model a simulation geometric model of the cable intermediate 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, so as to obtain a cable joint model; an interface pressure modeling module, which is used to set the spring stiffness and spring force corresponding to the nonlinear spring damper at the contact interface between the upper and lower layers of the cable joint model, so as to obtain a 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; a simulation solution module, which is used to perform nonlinear ultrasonic detection of the cable joint interface pressure simulation on the cable joint pressure model, and obtain the frequency spectrum at each point probe on the cable joint pressure model, so as to obtain the amplitude of harmonics and subharmonics under different interface pressures based on the frequency spectrum.

[0025] Furthermore, in the above-mentioned simulation device for harmonic detection of cable joint interface pressure, the modeling module includes: a thickness acquisition submodule, which is used to obtain the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint; a modeling submodule, which is used to perform an equivalent transformation on the cable intermediate joint based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint, establish a rectangular three-dimensional geometric model corresponding to the cable intermediate joint, and set materials and material parameters for the upper silicone rubber model and the lower cross-linked polyethylene model in the rectangular three-dimensional geometric model; wherein the rectangular 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 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, Poisson's ratio and damping ratio; an excitation source setting submodule, which is used to set a piecewise function for the upper surface of the upper silicone rubber model in the rectangular three-dimensional geometric model, and add a specified displacement 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; a boundary condition setting submodule, which is used to set the boundary conditions of the rectangular three-dimensional geometric model, and set the two sides of the rectangular three-dimensional geometric model as low-reflection boundaries; a mesh division submodule, which is used to establish tetrahedral meshes for the upper silicone rubber model and the lower cross-linked polyethylene model respectively based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene; a calculation setting submodule, which is used to determine and set the calculation mode of the interface pressure simulation of the nonlinear ultrasonic detection cable joint to transient calculation.

[0026] Furthermore, in the above-mentioned simulation device for harmonic detection of cable joint interface pressure, the excitation function F corresponding to the specified displacement in solid mechanics is added as follows:

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

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

[0029] Furthermore, the above-mentioned simulation device 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:

[0030]

[0031] Among them, 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; β is the stiffness damping of the corresponding material.

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

[0033] Furthermore, in the above-mentioned 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 insulating layers of the interface is calculated using the following formula:

[0034] △F=F st —F dt ;

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

[0036] Furthermore, in the above-mentioned simulation device for harmonic detection of cable joint interface pressure, the spring force per unit area of ​​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=3×1012N / m 3 , Δz is 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;

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

[0040]

[0041] Where b = 5, Z0 = 0.1 nm, γ is the damping coefficient of cross-linked polyethylene, which is 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 ztis the velocity of the upper surface of the lower cross-linked polyethylene model, υ zb is the velocity of the lower surface of the upper silicone rubber model.

[0042] Furthermore, in the above-mentioned simulation device for harmonic detection of cable joint interface pressure, the simulation solution module includes: a probe setting submodule, which is 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, which is used to add a probe drawing group to the set point probes to obtain the echo time domain signal at each point probe under different interface pressures; a spectrum graph acquisition submodule, which is used to transform the echo time domain signal at each point probe into a frequency domain signal by using a fast Fourier transform (FFT) to obtain the spectrum graph at each point probe; a harmonic amplitude extraction submodule, which is used to extract the amplitude of harmonics and subharmonics under different interface pressures according to the spectrum graph.

[0043] In yet another aspect, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method described in any one of the above aspects of the present invention.

[0044] In another aspect, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; 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 the above aspects of the present invention.

[0045] The present invention provides a simulation method, device and medium for harmonic detection of cable joint interface pressure. The simulation method belongs to a three-dimensional simulation method for nonlinear harmonic detection of cable intermediate joint interface pressure. For an actual high-voltage cable intermediate joint, a simulation geometric model of the cable intermediate joint is modeled, 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, so as to obtain a cable joint model; and a nonlinear spring damper is used to model the cable joint model to simulate the nonlinear interaction at the interface of the cable intermediate joint, so as to utilize the nonlinear harmonic detection principle to deeply explore the change of harmonic characteristics when the interface pressure changes, so as to establish the relationship between the two, so as to accurately simulate the state of the cable intermediate joint under various interface pressures, so as to fully consider the pressure at the interface of the cable intermediate joint, so that the simulation result has practical significance, and by establishing The new interface nonlinear model simulates and analyzes the cable joint interface pressure detection, which is highly innovative; the cable joint pressure model is used to simulate the cable joint interface pressure by nonlinear ultrasonic detection, and the spectrum diagram at the point probe is obtained to obtain the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram, so as to study the relationship between interface pressure and ultrasonic harmonic amplitude, that is, using the principle of nonlinear harmonic detection, deeply explore the changes in harmonic characteristics when the interface pressure changes, so as to establish the relationship between the two, provide support for further experimental research methods, and effectively avoid interference with actual cable joints, quickly and accurately evaluate interface pressure, provide key data for the design optimization of cable intermediate joints, help improve the joint structure to better cope with pressure changes, and solve the bottleneck problem of the experimental research on the relationship between interface pressure and ultrasonic harmonics. At the same time, this method helps to formulate scientific maintenance strategies to ensure safe and reliable power transmission and reduce maintenance costs and power outage losses caused by joint failures.

[0046] In addition, in terms of accuracy, this method, device, and medium combine nonlinear harmonic theory with three-dimensional simulation, which can keenly obtain harmonic changes caused by pressure changes, reduce errors, and provide scientific support for joint status assessment. At the same time, it avoids the problem of traditional detection damaging cable joints, ensuring the integrity and stability of the power system. For design and maintenance, based on simulation information, designers can optimize the joint structure, enhance its tolerance to pressure changes, and reduce the probability of failure. Maintenance personnel can customize strategies, reasonably arrange cycles and priorities, reduce unnecessary maintenance, reduce costs, and improve the economy of the power system. In terms of efficiency, a large number of working conditions can be quickly simulated to obtain pressure information, and the method is highly versatile and is not limited by joint type, size, or material. It has high application potential and academic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0048] Figure 1 A flowchart of a simulation method for harmonic detection of cable joint interface pressure provided by an embodiment of the present invention;

[0049] Figure 2 A specific flow chart of a simulation method for harmonic detection of cable joint interface pressure provided by an embodiment of the present invention;

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

[0051] Figure 4 A schematic diagram of the structure of the signal transmission and reception arrangement structure in the cable connector model provided by an embodiment of the present invention;

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

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

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

[0055] Figure 8 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] Fig. 9 A spectrum diagram at another receiving point when the interface pressure is 0 provided in an embodiment of the present invention;

[0057] Fig.10 A flowchart of the modeling steps provided by the embodiment of the present invention;

[0058] Fig.11 A flowchart of the interface pressure modeling step provided in an embodiment of the present invention;

[0059] Fig.12 A flowchart of the simulation solution steps provided by the embodiment of the present invention;

[0060] Fig.13 A structural block diagram of a simulation device for harmonic detection of cable joint interface pressure provided by an embodiment of the present invention;

[0061] Fig.14 A structural block diagram of a modeling module provided in an embodiment of the present invention;

[0062] Fig.15 A structural block diagram of an interface pressure modeling module provided in an embodiment of the present invention;

[0063] Fig.16 A structural block diagram of a simulation solution module provided in an embodiment of the present invention;

[0064] Fig.17 This is a structural block diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0065] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

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

[0067] Those skilled in the art can understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0068] It should also be understood that, in the embodiments of the present invention, “plurality” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[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 limited or otherwise indicated in the context.

[0070] In addition, the term "and / or" in the present invention is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0071] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0072] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

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

[0074] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

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

[0076] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, servers, etc., which can operate with many other general or special computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, servers, etc. 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 personal computers, small computer systems, large computer systems, and distributed cloud computing technology environments including any of the above systems, etc.

[0077] Electronic devices such as terminal devices, computer systems, servers, etc. can be described in the general context of computer system executable instructions (such as program modules) executed by computer systems. Generally, 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 a distributed cloud computing environment, where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0078] Method Example:

[0079] See also Figure 1 to Figure 2 , which shows the preferred process of the simulation method for harmonic detection of 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] In the modeling step S1, a simulation geometric model is built for the middle joint of the cable, 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, so as to obtain a cable joint model.

[0081] Specifically, based on the entity structure of the cable intermediate joint, the finite element software Abaqus is used to model the simulation geometry model, and by adding a specified displacement in solid mechanics on the upper surface of the first layer of the model, a segmented ultrasonic excitation source is set, that is, the specified displacement in solid mechanics added on the upper surface of the first layer of the model is used as the excitation function, and a segmented ultrasonic excitation source can be set on the upper surface of the first layer of the model, that is, multiple ultrasonic excitation sources are set at different positions to simulate the emission of ultrasonic waves, and a cable joint model is obtained, such as Figure 3 As shown in Figure 2. The position of the ultrasonic excitation source can be Figure 4 The signal is shown.

[0082] The interface pressure modeling step S2 sets the contact interface stiffness and interface pressure matching the nonlinear spring damper at the upper and lower contact interfaces of the cable joint model to obtain a cable joint pressure model, so as to simulate the nonlinear interaction force at the interface of the cable middle joint through the damping of the nonlinear spring damper.

[0083] Specifically, in the cable joint model, the contact interface stiffness and interface pressure matching the nonlinear spring damper can be set at the contact interface between the two insulating layers in the cable joint model, namely, the upper silicone rubber model and the lower cross-linked polyethylene model. That is, setting the contact interface stiffness and interface pressure matching the nonlinear spring damper is equivalent to establishing a nonlinear spring damper model at the interface. In other words, modeling is performed by the nonlinear spring damper to simulate the nonlinear interaction force at the interface through the nonlinear spring damper, and a cable joint pressure model with nonlinear harmonics is obtained, such as Figure 5 That is to say, by using the principle of nonlinear harmonic detection, we deeply explore the changes in harmonic characteristics when the interface pressure changes, so as to establish the relationship between the two and accurately simulate the state of the cable intermediate joint under various interface pressures.

[0084] In the simulation solution step S3, a nonlinear ultrasonic detection cable joint interface pressure simulation is performed on the cable joint pressure model to obtain a spectrum diagram at each point probe on the cable joint pressure model, so as to obtain the amplitudes of harmonics and subharmonics under different interface pressures based on the spectrum diagram.

[0085] Specifically, a plurality of point probes are arranged 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 may be located directly below a different ultrasonic excitation source. The cable joint pressure model may be subjected to nonlinear ultrasonic detection of the cable joint interface pressure simulation to obtain a spectrum at each point probe. For example, a spectrum at the point probe when the interface pressure is 0 may be obtained, such as Figure 7 and Fig. 9As shown in the figure, the interface pressure of the cable joint is detected based on nonlinear ultrasound, and the ultrasonic probe used in the ultrasonic detection is a one-transmit-one-receive type, so as to obtain the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram, so as to quickly and accurately evaluate the interface pressure, thereby providing key data for the design optimization of the intermediate joint of the cable, and helping to improve the joint structure to better cope with pressure changes. Among them, the position of the point probe can be Figure 4 At the signal receiving point shown, there are multiple point probes so as to extract echo waveforms of multiple points during ultrasonic detection to reduce errors.

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

[0087] The thickness obtaining sub-step S11 obtains the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint.

[0088] Specifically, the thickness of the joint silicone rubber and the cross-linked polyethylene of the cable body in the actual physical structure in the middle of the cable is measured to obtain the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint. The cable intermediate joint includes a three-layer structure, which is copper core or aluminum core, cross-linked polyethylene, and silicone rubber from the inside to the outside, and the cross-linked polyethylene and silicone rubber are used as insulation layers.

[0089] In the modeling sub-step S12, based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint, an equivalent transformation is performed on the cable intermediate joint to establish a rectangular three-dimensional geometric model corresponding to the cable intermediate joint, such as 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 rectangular three-dimensional geometric model are set; wherein the rectangular 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 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, first, the cable intermediate joint is equivalently transformed, and the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint are equivalent to a rectangular model with an adaptive thickness, and based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer obtained in the thickness acquisition sub-step S11, the finite element software Abaqus is used to establish an upper silicone rubber model and a lower cross-linked polyethylene model with corresponding thicknesses of the cross-linked polyethylene layer and the silicone rubber layer, and the upper silicone rubber model and the lower cross-linked polyethylene model are stacked up and down to form an overall model. Then, the material setting is performed on the upper silicone rubber model and the lower cross-linked polyethylene model, that is, the materials of the upper silicone rubber model and the lower cross-linked polyethylene model are set in silicone rubber and cross-linked polyethylene respectively. Finally, the material parameters of the corresponding geometric model parts, namely the upper silicone rubber model and the lower cross-linked polyethylene model, are set respectively, that is, the material parameters of the upper silicone rubber model and the lower cross-linked polyethylene model are set respectively, and the material parameters include elastic modulus E, density ρ and Poisson's ratio σ, and can also include damping ratio. 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 μ can be determined using the following formula:

[0091]

[0092] Among them, 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; 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 rectangular 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.

[0094] Specifically, the emission of ultrasound is simulated by adding a specified displacement in 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] Among them, A is the excitation signal amplitude, which is set to 500nm; f is the excitation signal frequency, which is set to 26165Hz; n is the number of cycles of the excitation wave, which is set to 10; and t is the excitation signal time.

[0097] The boundary condition setting sub-step S14 sets the boundary conditions of the rectangular three-dimensional geometric model, and sets the two sides of the rectangular three-dimensional geometric model as low-reflection boundaries.

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

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

[0100] Specifically, a tetrahedral mesh is established. According to the different ultrasonic sound velocities of the materials corresponding to different domains, the mesh sizes of different domains are different, usually 1 / 12 of the wavelength λ, where λ is:

[0101]

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

[0103] The calculation setting sub-step S16 determines and sets the calculation mode of the nonlinear ultrasonic detection cable joint interface pressure simulation to transient calculation.

[0104] Specifically, transient calculation is used in the simulation of interface pressure of nonlinear ultrasonic testing cable joints.

[0105] See also Fig.11 , which is a flowchart of the interface pressure modeling step provided by an embodiment of the present invention. As shown in the figure, the interface pressure modeling step S2 includes the following sub-steps:

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

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

[0108] The pressure setting sub-step S22 sets the interface pressure of the contact interface between the two insulating layers in the cable joint model to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface, 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, that is, 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 △F is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F is the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model; dt is the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable connector model.

[0112] In this embodiment, the spring force per unit area of ​​the lower surface of the upper silicone rubber model in the cable connector 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=3×1012N / m 3 , Δz is 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;

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

[0116]

[0117] Where b = 5, Z0 = 0.1 nm, γ is the damping coefficient of cross-linked polyethylene, which is 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 is the velocity of the upper surface of the lower cross-linked polyethylene model, υ zb is the velocity of the lower surface of the upper silicone rubber model.

[0118] See also Fig.12 , which is a flowchart of the simulation solution step provided by an embodiment of the present invention. As shown in the figure, the simulation solution step S3 includes the following sub-steps:

[0119] In the 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 are arranged on the lower surface of the second layer material of the model, ie, the lower cross-linked polyethylene model, and the positions of the point probes are all 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 plot group is added to the result data set to obtain the change trend of the echo amplitude at different points under different interface pressures over time, i.e., the echo time domain signal, such as Figure 6 and Figure 8 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 by using a fast Fourier transform to acquire the spectrum at each probe point.

[0124] Specifically, the echo time domain signals at different receiving points are transformed into frequency domain signals using Fast Fourier Transform (FFT), and the spectrum diagrams at different receiving points are obtained, such as Figure 7 and Fig. 9 shown.

[0125] The harmonic amplitude extraction sub-step S34 extracts the amplitudes of harmonics and subharmonics under different interface pressures according to the frequency spectrum.

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

[0127] In this embodiment, in the modeling step S1, the surface with higher stiffness is set as the main surface, and the surface with lower stiffness is selected as the slave surface. That is, the surface with higher stiffness among the lower surface of the first layer and the upper surface of the second layer in the cable connector model is set as the main surface, and 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 a three-dimensional simulation method for nonlinear harmonic detection of cable intermediate joint interface pressure. For the actual high-voltage cable intermediate joint, the cable intermediate joint is simulated by modeling a geometric model, 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, so as to obtain a cable joint model; and on the cable joint model, a nonlinear spring damper is used to model the nonlinear interaction at the interface of the cable intermediate joint, so as to utilize the principle of nonlinear harmonic detection to deeply explore the changes in harmonic characteristics when the interface pressure changes, so as to establish the relationship between the two, so as to accurately simulate the state of the cable intermediate joint under various interface pressures, so as to fully consider the pressure at the interface of the cable intermediate joint, so that the simulation results have practical significance, and by establishing a new interface The nonlinear model simulates and analyzes the cable joint interface pressure detection, which is highly innovative; the cable joint pressure model is simulated by nonlinear ultrasonic detection of the cable joint interface pressure, and the spectrum diagram at the point probe is obtained to obtain the amplitude of harmonics and subharmonics under different interface pressures based on the spectrum diagram, so as to study the relationship between interface pressure and ultrasonic harmonic amplitude, that is, using the principle of nonlinear harmonic detection, deeply explore the changes in harmonic characteristics when the interface pressure changes, so as to establish the relationship between the two, provide support for further experimental research methods, and effectively avoid interference with actual cable joints, quickly and accurately evaluate the interface pressure, provide key data for the design optimization of cable intermediate joints, help improve the joint structure to better cope with pressure changes, and solve the bottleneck problem of the experimental research on the relationship between interface pressure and ultrasonic harmonics. At the same time, this method helps to formulate scientific maintenance strategies to ensure safe and reliable power transmission and reduce maintenance costs and power outage losses caused by joint failures.

[0129] In addition, in terms of accuracy, this method combines nonlinear harmonic theory with three-dimensional simulation, which can keenly obtain harmonic changes caused by pressure changes, reduce errors, and provide scientific support for joint status assessment. At the same time, it avoids the problem of traditional detection damaging cable joints, ensuring the integrity and stability of the power system. For design and maintenance, based on simulation information, designers can optimize the joint structure, enhance its tolerance to pressure changes, and reduce the probability of failure. Maintenance personnel can customize strategies, reasonably arrange cycles and priorities, reduce unnecessary maintenance, reduce costs, and improve the economy of the power system. In terms of efficiency, a large number of working conditions can be quickly simulated to obtain pressure information, and the method is highly versatile and is not limited by joint type, size, or material. It has high application potential and academic value.

[0130] Device Example:

[0131] See also Fig.13, which is a structural block diagram of a simulation device for harmonic detection of cable joint interface pressure provided by an embodiment of the present invention. As shown in the figure, the device also includes: a modeling module 100, an interface pressure modeling module 200 and a simulation solution module 300; wherein, the modeling module 100 is used to model the simulation geometric model of the cable intermediate 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 to obtain 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 to obtain a 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; the simulation solution 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 point probe 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 also Fig.14 , which is a structural block diagram of the modeling module provided by an embodiment of the present 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 meshing submodule 150 and a calculation setting submodule 160; wherein, the thickness acquisition submodule 110 is used to obtain the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint; the modeling submodule 120 is used to perform an equivalent transformation on the cable intermediate joint based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint, establish a rectangular three-dimensional geometric model corresponding to the cable intermediate joint, and perform material settings and material parameter settings on the upper silicone rubber model and the lower cross-linked polyethylene model in the rectangular three-dimensional geometric model; wherein, the rectangular 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 intermediate joint, and the lower cross-linked polyethylene model is adapted to the silicone rubber layer in the cable intermediate joint. The thickness is adapted to the thickness of the cross-linked polyethylene layer in the intermediate joint of the cable; the material parameters include: elastic modulus, density, Poisson's ratio and damping ratio; the excitation source setting submodule 130 is used to set a piecewise function for the upper surface of the upper silicone rubber model in the rectangular three-dimensional geometric model, and add a specified displacement 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 condition setting submodule 140 is used to set the boundary conditions of the rectangular three-dimensional geometric model, and set the two sides of the rectangular three-dimensional geometric model as low-reflection boundaries; the meshing submodule 150 is used to establish tetrahedral meshes for the upper silicone rubber model and the lower cross-linked polyethylene model respectively based on the ultrasonic wavelengths of silicone rubber and cross-linked polyethylene; the calculation setting submodule 160 is used to determine and set the calculation mode of the nonlinear ultrasonic detection cable joint interface pressure simulation to transient calculation.

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

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

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

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

[0137]

[0138] Among them, 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; β is the stiffness damping of the corresponding material.

[0139] See also Fig.15 , which is a structural block diagram of the interface pressure modeling module provided by an embodiment of the present 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 insulating 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 of the contact interface between the two insulating layers in the cable joint model to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating 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 △F is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F is the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model; dt is the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable connector model.

[0143] Preferably, the spring force per unit area of ​​the lower surface of the upper silicone rubber model in the cable connector 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=3×1012N / m 3 , Δz is 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;

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

[0147]

[0148] Where b = 5, Z0 = 0.1 nm, γ is the damping coefficient of cross-linked polyethylene, which is 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 is the velocity of the upper surface of the lower cross-linked polyethylene model, υ zb is the velocity of the lower surface of the upper silicone rubber model.

[0149] See also Fig.16 , which is a structural block diagram of the simulation solution module provided by an embodiment of the present 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 a probe drawing group to the set point probes to obtain the echo time domain signal at each point probe under different interface pressures; the spectrum acquisition submodule 330 is used to transform the echo time domain signal at each point probe into a frequency domain signal by using a 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 according to the spectrum.

[0150] Electronic device embodiment:

[0151] See also Fig.17 , which is a structural block diagram of an electronic device provided by an embodiment of the present invention. Fig.17 As shown, the electronic device 400 includes one or more processors 41 and a memory 42 .

[0152] The processor 41 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities 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, and the computer program product 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 (cache), etc. 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 run the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above and / or other desired functions. In one example, the electronic device may also include: an input device 43 and an output device 44, which are 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, and can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0156] Of course, to simplify, Fig.17 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0157] Computer program product and computer readable storage medium embodiments:

[0158] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above-mentioned "Exemplary Method" section of this specification.

[0159] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the embodiments of the present invention, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0160] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above “Exemplary Method” section of this specification.

[0161] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, system or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0162] The basic principle of the present invention is described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. must be possessed by each embodiment of the present invention. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, rather than limitation, and the above details do not limit the present invention to being implemented by adopting the above specific details.

[0163] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0164] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0165] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware or any combination of software, hardware, firmware. The above order of steps for the method is only for illustration, and the steps of the method of the present invention are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers a recording medium storing a program for executing the method according to the present invention.

[0166] It should also be noted that in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in the field to make or use the present invention. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but in accordance with the widest range consistent with the principles and novel features disclosed here.

[0167] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A simulation method for harmonic detection of cable joint interface pressure, characterized in that: The steps include: A simulation geometric model of the cable intermediate joint is modeled, 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 to obtain a cable joint model; At the upper and lower contact interfaces of the cable joint model, a contact interface stiffness and an interface pressure matching the nonlinear spring damper are set to obtain a cable joint pressure model, so as to simulate the nonlinear interaction pressure at the interface of the cable middle joint through the damping of the nonlinear spring damper; The nonlinear ultrasonic detection of the cable joint interface pressure simulation is performed on the cable joint pressure model to obtain the spectrum diagram at each point probe on the cable joint pressure model, so as to obtain the amplitude of the harmonics and subharmonics under different interface pressures based on the spectrum diagram.

2. The simulation method for harmonic detection of cable joint interface pressure according to claim 1 is characterized in that: The method of modeling a simulation geometric model of the cable intermediate 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 intermediate joint; Based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint, the cable intermediate joint is equivalently transformed, a rectangular three-dimensional geometric model corresponding to the cable intermediate joint is established, and material settings and material parameters are set for the upper silicone rubber model and the lower cross-linked polyethylene model in the rectangular three-dimensional geometric model; wherein the rectangular 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 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, Poisson's ratio and damping ratio; A piecewise function is set on the upper surface of the upper silicone rubber model in the rectangular 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 an ultrasonic excitation source to simulate the emission of ultrasonic waves; Setting boundary conditions of the three-dimensional rectangular parallelepiped geometric model, setting two sides of the three-dimensional rectangular parallelepiped geometric model 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; Determine and set the calculation mode of nonlinear ultrasonic testing cable joint interface pressure simulation to transient calculation.

3. The simulation method for harmonic detection of cable joint interface pressure according to claim 2 is characterized in that: The activation function F corresponding to the specified displacement in the added solid mechanics is: F=A(1-cos(2*π*f*t / n))*sin(2*π*f*t); Among them, A is the excitation signal amplitude, which is set to 500nm; f is the excitation signal frequency, which is set to 26165Hz; n is the number of cycles of the excitation wave, which is set to 10; and t is the excitation signal time.

4. The simulation method for harmonic detection of cable joint interface pressure according to claim 2 is 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: Among them, 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; β is the stiffness damping of the corresponding material.

5. The method for simulating interface pressure of a harmonic detection cable joint according to any one of claims 1 to 4, characterized in that: The step of setting the contact interface stiffness and interface pressure matching the nonlinear spring damper at the upper and lower contact interfaces of the cable joint model to obtain the cable joint pressure model comprises the following steps: The contact interface stiffness between the two insulating layers in the cable joint model is set to the spring stiffness in the nonlinear spring damper; The interface pressure of the contact interface between the two insulating layers in the cable joint model is set to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

6. The method for simulating the interface pressure of a harmonic detection cable joint according to claim 5, 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 △F is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F is the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model; dt is the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable connector model.

7. The method for simulating interface pressure of a harmonic detection cable joint according to claim 5, characterized in that: The spring force per unit area of ​​the lower surface of the upper silicone rubber model in the cable connector model is calculated using the following formula: Where a = 4, b = 5, Z0 = 0.1 nm, k1 = 5 × 1012 N / m 3 , k1=3×1012N / m 3 , Δz is 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 connector model is calculated using the following formula: Where b = 5, Z0 = 0.1 nm, γ is the damping coefficient of cross-linked polyethylene, which is 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 is the velocity of the upper surface of the lower cross-linked polyethylene model, υ zb is the velocity of the lower surface of the upper silicone rubber model.

8. The method for simulating interface pressure of a harmonic detection cable joint according to any one of claims 1 to 4, characterized in that: The method of performing nonlinear ultrasonic detection of the cable joint interface pressure simulation on the cable joint pressure model to obtain the frequency spectrum at each point probe on the cable joint pressure model comprises the following steps: At least three point probes are arranged on the lower surface of the second layer in the cable joint model; Add a probe drawing group to the set point probes to obtain the echo time domain signals at each point probe under different interface pressures; The echo time domain signal at each probe point is transformed into a frequency domain signal by using Fast Fourier Transform (FFT) to obtain the spectrum diagram at each probe point; The amplitudes of harmonics and subharmonics under different interface pressures are extracted based on the spectrum.

9. A simulation device for harmonic detection of cable joint interface pressure, characterized in that: include: A modeling module is used to model a simulation geometric model of the cable intermediate 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 to obtain a cable joint model; An interface pressure modeling module is used to set a contact interface stiffness and an interface pressure matching the nonlinear spring damper at the upper and lower contact interfaces of the cable joint model to obtain a cable joint pressure model, so as to simulate the nonlinear interaction force at the interface of the cable middle joint through the damping of the nonlinear spring damper; The simulation solution module 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 point probe on the cable joint pressure model, and obtain the amplitude of the harmonics and subharmonics under different interface pressures based on the spectrum diagram.

10. The device for simulating the interface pressure of a cable joint according to claim 9, characterized in that: The modeling module includes: The thickness acquisition submodule is used to obtain the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint; A modeling submodule, for performing an equivalent transformation on the cable intermediate joint based on the thickness of the cross-linked polyethylene layer and the silicone rubber layer in the cable intermediate joint, establishing a rectangular three-dimensional geometric model corresponding to the cable intermediate joint, and setting materials and material parameters for an upper silicone rubber model and a lower cross-linked polyethylene model in the rectangular three-dimensional geometric model; wherein the rectangular 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 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, Poisson's ratio and damping ratio; An excitation source setting submodule is used to set a piecewise function for the upper surface of the upper silicone rubber model in the rectangular 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 an excitation function to set an ultrasonic excitation source to simulate the emission of ultrasonic waves; A boundary condition setting submodule is used to set the boundary conditions of the rectangular three-dimensional geometric model, and set the two sides of the rectangular three-dimensional geometric model as low-reflection boundaries; A meshing submodule is used to establish tetrahedral meshes for the upper silicone rubber model and the lower cross-linked polyethylene model respectively based on the ultrasonic wavelengths of the silicone rubber and the cross-linked polyethylene; The calculation setting submodule is used to determine and set the calculation mode of the nonlinear ultrasonic detection cable joint interface pressure simulation to transient calculation.

11. The device for simulating interface pressure of a harmonic detection cable joint according to claim 10, characterized in that: The activation function F corresponding to the specified displacement in the added solid mechanics is: F=A(1-cos(2*π*f*t / n))*sin(2*π*f*t); Among them, A is the excitation signal amplitude, which is set to 500nm; f is the excitation signal frequency, which is set to 26165Hz; n is the number of cycles of the excitation wave, which is set to 10; and t is the excitation signal time.

12. The device for simulating interface pressure of a harmonic detection cable joint according to claim 10, 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: Among them, 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; β is the stiffness damping of the corresponding material.

13. The simulation device for harmonic detection of cable joint interface pressure according to any one of claims 9 to 12, characterized in that: The interface pressure modeling module includes: A stiffness conversion submodule is used to set the contact interface stiffness between two insulating 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 of the contact interface between the two insulating layers in the cable joint model to the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface, so as to simulate the nonlinear interaction at the interface through the nonlinear spring damper.

14. The device for simulating interface pressure of a harmonic detection cable joint according to claim 13, 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 △F is the difference in spring force corresponding to the nonlinear spring damper applied between the two insulating layers of the interface; F st F is the spring force per unit area on the lower surface of the upper silicone rubber model in the cable connector model; dt is the spring force per unit area on the upper surface of the lower cross-linked polyethylene model in the cable connector model.

15. The device for simulating interface pressure of a harmonic detection cable joint according to claim 14, characterized in that: The spring force per unit area of ​​the lower surface of the upper silicone rubber model in the cable connector model is calculated using the following formula: Where a = 4, b = 5, Z0 = 0.1 nm, k1 = 5 × 1012 N / m 3 , k1=3×1012N / m 3 , Δz is 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 connector model is calculated using the following formula: Where b = 5, Z0 = 0.1 nm, γ is the damping coefficient of cross-linked polyethylene, which is 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 is the velocity of the upper surface of the lower cross-linked polyethylene model, υ zb is the velocity of the lower surface of the upper silicone rubber model.

16. The device for simulating interface pressure of a harmonic detection cable joint according to any one of claims 9 to 12, characterized in that: The simulation solution module includes: A probe setting submodule, used for setting 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 a probe drawing group to the set point probes to 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 by using a fast Fourier transform (FFT) to acquire the spectrum at each probe point; The harmonic amplitude extraction submodule is used to extract the amplitudes of harmonics and subharmonics under different interface pressures according to the spectrum diagram.

17. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 8.

18. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is used to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 8.

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