Multi-physics field coupling experiment platform for submarine power cable

Abstract

In the platform, a submarine cable penetrates through an impounding reservoir, a lifting support is arranged in the impounding reservoir and supports the submarine cable in a lifting mode to form a local suspension section, and a flow generation system is arranged in the impounding reservoir to generate uniform flow and oscillatory flow towards the local suspension section. The first temperature probe measures the first temperature of a submarine cable insulating layer of the local suspension section, the second temperature probe measures the second temperature of a conductor of the local suspension section, the fiber grating sensor measures strain parameters of the local suspension section during oscillation in water, and the ultrasonic flow meter is arranged in the reservoir to measure the flow velocity. The feed-through transformer is arranged around the submarine cable outside the reservoir so as to conduct current to the submarine cable through electromagnetic induction, and the lightning surge generator is connected with the submarine cable outside the reservoir so as to generate overvoltage on a submarine cable conductor. The oscilloscope is connected with the submarine cable outside the reservoir to monitor the waveform of the overvoltage and the voltage waveform sensed by the shielding layer of the submarine cable.

Description

Technical Field

[0001] The invention relates to the technical field of submarine power cable operation characteristic analysis, in particular to a submarine power cable multi-physical field coupling experimental platform. Background Art

[0002] After the submarine cable is laid on the seabed, the scouring of ocean currents and submarine geological activities change the laying environment of the submarine cable, resulting in partially exposed or even suspended sections where the submarine cable is not in direct contact with the seabed surface. The suspended section of the submarine cable produces extreme response and vortex-induced vibration response under the action of wave flow, which will cause strength failure and fatigue damage of the cable, and damage the submarine cable structure. Therefore, it is very necessary to analyze the operation characteristics of the submarine cable under the conditions of force, electricity and heat coupling.

[0003] Existing research on the operating characteristics of submarine cables mostly only considers single physical fields such as force or electricity, ignoring the effects of multi-physical field coupling and the influence of environmental parameters on material parameter performance. There are few experimental studies on the operating characteristics of submarine cables under simulated real ocean environments and multi-physical field coupling.

[0004] The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0005] In view of the shortcomings or defects of the above-mentioned prior art, a submarine power cable multi-physical field coupling experimental platform is provided, which simulates the real marine environment and the monitoring of the operating characteristics of the submarine power cable under the coupling of the "force-electricity-heat" multi-physical fields; it is of great value for studying the real operation of the submarine cable, as well as remote fault diagnosis, status warning, risk assessment and deduction.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A submarine power cable multi-physics field coupling experimental platform includes:

[0008] Reservoirs,

[0009] A submarine cable passing through the reservoir,

[0010] A lifting bracket is arranged in the water reservoir and can lift and lower the submarine cable to form a partially suspended section.

[0011] a flow-generating system, which is arranged in the water reservoir to generate a uniform flow and an oscillating flow toward the local suspended section,

[0012] a first temperature probe for measuring a first temperature of an insulation layer of the submarine cable of the local suspended section,

[0013] a second temperature probe measuring a second temperature of the conductor of the partially suspended segment,

[0014] a fiber grating sensor for measuring the strain parameters of the local suspended segment when it oscillates in water,

[0015] An ultrasonic flow meter is arranged in the water reservoir to measure the flow velocity,

[0016] A through-hole transformer is arranged around the submarine cable outside the reservoir to pass current through the submarine cable by electromagnetic induction.

[0017] a lightning surge generator connected to a submarine cable outside the reservoir to generate an overvoltage on a submarine cable conductor,

[0018] An oscilloscope is connected to the submarine cable outside the water reservoir to monitor the waveform of the overvoltage and the waveform of the voltage induced by the shielding layer of the submarine cable.

[0019] The multi-physical field coupling experimental platform for submarine power cables also includes a computer connected to the flow generation system and the fiber grating sensor, which processes the strain data of the submarine cable under the action of uniform flow or oscillating flow measured by the fiber grating sensor to obtain the vortex-induced vibration response of the submarine cable, wherein the computer performs spectrum analysis on the strain time-varying curve to obtain the peak frequency as the natural frequency of the submarine cable, and obtains the time-varying data of the displacement of the submarine cable by performing modal analysis on the strain data to analyze its vibration characteristics.

[0020] In the submarine power cable multi-physical field coupling experimental platform, the computer is connected to the first temperature probe, the second temperature probe, the ultrasonic flow meter, the through-hole transformer and the lightning surge generator. The computer adjusts the through-hole transformer to generate a relationship curve between current, flow rate and the first temperature and the second temperature. The computer controls the lightning surge generator to adjust the lightning overvoltage.

[0021] In the submarine power cable multi-physics field coupling experimental platform, the flow generation system generates a uniform flow with a maximum speed of 4 m / s and an oscillating flow with a peak value of 2 m / s in the reservoir.

[0022] In the submarine power cable multi-physical field coupling experimental platform, the angle between the flow direction and the wave direction of the oscillating flow varies between 0-90°.

[0023] In the submarine power cable multi-physical field coupling experimental platform, the lifting range of the lifting rod bracket is 0.5 to 1.5 m, and a buffer layer is provided between the lifting bracket and the submarine cable.

[0024] In the submarine power cable multi-physics field coupling experimental platform, the second temperature probe is buried at a depth of 10 mm in the conductor of the submarine cable.

[0025] In the submarine power cable multi-physical field coupling experimental platform, the velocity measurement range of the ultrasonic flow meter is 0-5 m / s, the velocity measurement error is within 0.001 m / s, and the maximum sampling frequency is 70 Hz.

[0026] In the submarine power cable multi-physical field coupling experimental platform, the range of the fiber grating sensor is ±1500με, the central working wavelength range is 1525-1560 nm, and the lightning surge generator can generate a standard lightning wave waveform of 1.2 / 50us, with a voltage peak of 5 kV and a current peak of 2.5 kA.

[0027] In the submarine power cable multi-physics field coupling experimental platform, the maximum current applied to the through-hole transformer is 2500A to perform temperature rise experiments and imbalance detection.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention is a submarine power cable "force-electricity-heat" multi-physics field coupling experimental platform, which is used to simulate the operating characteristics of submarine power cables in real marine environments. It improves the experimental accuracy and coupling degree. It is of great value in studying the real operation of submarine cables, as well as remote fault diagnosis, status warning, risk assessment and deduction.

[0030] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to achieve the extent that those skilled in the art can implement it according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0032] In the attached picture:

[0033] Figure 1 It is a structural schematic diagram of the present invention;

[0034] Figure 2 This is a schematic diagram of burying the second temperature probe of the present invention;

[0035] Figure 3 It is a schematic diagram of the submarine cable suspension span of the present invention;

[0036] Figure 4 It is a schematic diagram of the frequency domain response under the action of the square wave signal of the present invention.

[0037] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0038] The following will refer to the attached Figures 1 to 4 Specific embodiments of the present invention are described in more detail. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0039] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0040] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0041] For a better understanding, Figures 1 to 3 As shown, a submarine power cable multi-physics field coupling experimental platform includes:

[0042] Reservoir 2,

[0043] The submarine cable 1 passes through the reservoir 2.

[0044] A lifting bracket 4 is disposed in the water reservoir 2 and can lift and lower the submarine cable 1 to form a partially suspended section.

[0045] a flow generating system 3, which is arranged in the water reservoir 2 to generate a uniform flow and an oscillating flow toward the local suspended section,

[0046] a first temperature probe 5, which measures a first temperature of the insulation layer of the submarine cable 1 of the local suspended section,

[0047] A second temperature probe 6, which measures a second temperature of the conductor of the partially suspended section,

[0048] a fiber grating sensor 8 for measuring the strain parameters of the local suspended segment when it oscillates in water,

[0049] An ultrasonic flow meter 7 is arranged in the water reservoir 2 to measure the flow velocity.

[0050] A through-hole transformer 9 is arranged around the submarine cable 1 outside the reservoir 2 to pass current through the submarine cable 1 by electromagnetic induction.

[0051] A lightning surge generator 14 is connected to the submarine cable 1 outside the reservoir 2 to generate an overvoltage on the conductor of the submarine cable 1.

[0052] The oscilloscope 10 is connected to the submarine cable 1 outside the water reservoir 2 to monitor the waveform of the overvoltage and the voltage waveform induced by the shielding layer of the submarine cable 1 .

[0053] In a preferred embodiment of the submarine power cable multi-physical field coupling experimental platform, a computer is also included that is connected to the flow generation system 3 and the fiber grating sensor 8, which processes the strain data of the submarine cable 1 under the action of uniform flow or oscillating flow measured by the fiber grating sensor 8 to obtain the vortex-induced vibration response of the submarine cable 1, wherein the computer performs a spectrum analysis on the strain time-varying curve to obtain the peak frequency as the natural frequency of the submarine cable 1, and obtains the time-varying data of the displacement of the submarine cable 1 by performing a modal analysis on the strain data to analyze its vibration characteristics.

[0054] In one embodiment, frequency domain analysis converts the periodic excitation signal and response into the sum of several sinusoidal wave signals, and calculates the amplitude amplification factor of each frequency respectively. The frequency with the largest amplitude amplification factor is closer to the natural frequency. Take a periodic square wave as an example:

[0055] Assume that a system is excited by a periodic square wave, the value of which is F0 and the period is T.

[0056] (1)

[0057] Expanding it into a Fourier series: ,in , is the angular frequency of the excitation system. After converting the periodic excitation into the sum of several sine waves, the response of each frequency excitation can be obtained separately, and then the responses are synthesized into the total response. Each frequency has its amplitude amplification factor β, which represents the response replica size generated by the excitation at a specific frequency and a specific assignment. The amplitude amplification factor is calculated as:

[0058] (2)

[0059] in , is the natural frequency of the system, is the damping coefficient, both of which are independent of excitation. By using software to plot the amplitude amplification factor, the natural frequency of the system can be obtained.

[0060] like Figure 4 As shown, it is for a , The frequency domain response of the system under the action of the above square wave signal. The natural frequency of the system is six times the excitation frequency, so and The amplitude amplification factor is larger.

[0061] Furthermore, for a linear multi-degree-of-freedom system, there are multiple natural frequencies equal to the number of degrees of freedom n. Each natural frequency corresponds to a specific vibration mode of the system. The natural frequency and vibration mode determine the form of the free vibration of the system, which is called the mode of the system. There are two main types of modal analysis, modal decomposition and modal testing. Modal decomposition is to analyze the modes of a known system through its mass matrix, damping matrix, and stiffness matrix, and modal testing is to analyze its modes through external excitation and vibration displacement. This modal analysis mainly uses nonlinear weighted least squares method for multi-modal identification.

[0062] According to the frequency band, the modes are divided into the modes to be identified n1~n2, the low frequency band 1~n1-1 and the high frequency band n2+1~n. The frequency response function in the fitting frequency band can be expressed as:

[0063] (3)

[0064] in, is the complex feature quality; They are the complex modal mass, complex modal stiffness, complex modal frequency, and complex modal damping ratio of the structural damping system respectively; are all complex modal vectors, which are arrays of displacement amplitudes of the free response of the complex modal system. The subsequent analysis steps are:

[0065] Based on the measured frequency response function, the single mode identification method is used to estimate the complex mode frequency and damping in the fitting frequency band. , . Use the above calculated values ​​as initial values, iterate, and calculate the linear parameters and variance. If the calculated variance does not meet the requirements, then give and Add a small increment and , get the complex modal frequency and damping of the next iteration , Until the variance is less than the precision When , the iteration is terminated and the linear parameters and complex modal frequencies and damping are output. , .

[0066] In the preferred embodiment of the submarine power cable multi-physics field coupling experimental platform, the computer is connected to the first temperature probe 5, the second temperature probe 6, the ultrasonic flow meter 7, the through-core transformer 9 and the lightning surge generator 14, the computer adjusts the through-core transformer 9 to generate a relationship curve between current, flow rate, first temperature and second temperature, and the computer controls the lightning surge generator 14 to generate lightning overvoltage. The temperature value displayed on the temperature sensor can be monitored, the current value passing through the through-core transformer can be changed, and then the conductor temperature can be changed until the conductor temperature reaches a suitable range. In the preferred embodiment of the submarine power cable multi-physics field coupling experimental platform, the flow generation system 3 generates a uniform flow with a maximum velocity of 4 m / s and an oscillating flow with a peak value of 2 m / s in the reservoir 2.

[0067] In a preferred embodiment of the submarine power cable multi-physical field coupling experimental platform, the angle between the flow direction and the wave direction of the oscillating flow varies between 0-90°.

[0068] In a preferred embodiment of the submarine power cable multi-physical field coupling experimental platform, the lifting range of the lifting rod bracket is 0.5 to 1.5 m, and a buffer layer is provided between the lifting bracket 4 and the submarine cable 1 .

[0069] In a preferred embodiment of the submarine power cable multi-physical field coupling experimental platform, the second temperature probe 6 is buried at a depth of 10 mm in the conductor of the submarine cable 1 .

[0070] In the preferred embodiment of the submarine power cable multi-physics field coupling experimental platform, the speed measurement range of the ultrasonic flow meter is 0~5 m / s, the speed measurement error is within 0.001 m / s, and the sampling frequency is up to 70 Hz. In the preferred embodiment of the submarine power cable multi-physics field coupling experimental platform, the range of the fiber grating sensor is ±1500 με, the central working wavelength range is 1525-1560 nm, and the lightning surge generator 14 can generate a standard lightning wave waveform of 1.2 / 50us, with a voltage peak of 5kV and a current peak of 2.5 kA. In the preferred embodiment of the submarine power cable multi-physics field coupling experimental platform, the through-core transformer 9 applies a maximum current of 2500 A to perform temperature rise experiments and imbalance detection.

[0071] In one embodiment, a submarine power cable multi-physics field coupling experimental platform is composed of a water reservoir 2, a flow generation system 3, a lifting bracket 4, a flow meter, a fiber optic Bragg grating sensor 8, two sets of temperature probes, an oscilloscope 10, a lightning surge generator 14, and a set of through-core transformers 9. The experimental platform can control the temperature of the submarine cable 1 by passing current through the through-core transformer 9 using electromagnetic induction. The flow generation system 3 in the water reservoir 2 can create water flow, causing vortex-induced vibration in the local suspended section of the submarine cable 1 in the water reservoir, and the seawater flow rate can be monitored by the flow meter. The lightning surge generator is used to generate lightning overvoltage, and the electromagnetic transient response of the submarine cable 1 can be analyzed by waveform analysis of the oscilloscope 10. Figure 1 As shown. The components in the reservoir 2 are responsible for stress monitoring and vibration characteristic analysis of the submarine cable 1; the through-core transformer 9 is responsible for inducing current on the conductor of the submarine cable 1 through the law of electromagnetic induction and controlling the conductor temperature of the submarine cable 1; the lightning surge generator 14 and the oscilloscope 10 are used to apply lightning overvoltage to the cable conductor and monitor the electromagnetic induction phenomenon of the shielding layer.

[0072] In one embodiment, the reservoir 2 is 40 m long, 2 m wide and 1.5 m deep, and is the main test site for the strain and vibration response of the submarine cable 1. The flow system 3 can generate a uniform flow with a maximum velocity of 3.5 m / s and an oscillating flow with a peak value of 2.5 m / s in the reservoir. The angle between the flow direction and the wave direction can be changed between 0 and 90° as required. The lifting bracket 4 is used to support the submarine cable 1 to form a local suspended section, simulating the following example: Figure 1 The actual suspension of the submarine cable 1 on the seabed is shown in the figure, and the lifting range is 0.3 m to 1.0 m. In order to avoid damage to the cable insulation layer, a buffer layer needs to be added between the bracket and the submarine cable 1. The two temperature probes are used to monitor the temperature of the insulation layer and the conductor of the submarine cable 1 respectively. The second temperature probe 6 is arranged as shown in the figure. Figure 2As shown, the second temperature probe 6 is buried at a depth of about 10 mm in the conductor 21 of the submarine cable 1; the conductor shielding layer 22, the insulating layer 23, the insulating shielding layer 24, the semi-conductive water layer 25, the alloy lead sheath 26, the PE sheath 27, the steel wire armor 28, the PP outer sheath 29, and the heat preservation material 30 wrapping the temperature probe constitute the submarine cable 1.

[0073] In one embodiment, the ultrasonic flow meter 7 has a velocity measurement range of 0~4 m / s and a sampling frequency of 1~ 400 Hz. The fiber grating sensor 8 is used to monitor the strain parameters of the submarine cable 1 when it oscillates in a water pool. The principle is that when stress acts, the refractive index of the grating core changes, thereby changing the wavelength of the reflected light. By comparing the wavelength of the reflected light before and after the strain occurs, the strain magnitude can be obtained. The sampling rate of the selected fiber grating sensor 8 is 1000 Hz, and the wavelength range is 1510-1590 nm. By performing a spectrum analysis on the strain time-varying curve, the peak frequency can be obtained, which is the natural frequency of the submarine cable 1. By performing a modal analysis on the strain of the submarine cable 1, the time-varying data of the displacement of the submarine cable 1 can be obtained, and its vibration characteristics can be analyzed. The through-core transformer 9 can perform temperature rise experiments and imbalance detection on multiple cables with a length of less than 100 meters. The experimental platform is equipped with 42 through-core transformers, and the maximum current that can be applied is 2500 A. The bandwidth of the four-channel oscilloscope 10 is 200 MHz, and the sampling rate is 5 GS / s. The first cable 11 and the second cable 12 connecting the shielding layer and the conductor of the submarine cable 1 are as follows: Figure 1 The connector 13 of the submarine cable 1 is used to connect the submarine cable 1, and the lightning surge generator 14 can generate a voltage peak of 5 kV and a current peak of 2.5 kA.

[0074] During the experiment, firstly, current is passed through the conductor of the submarine cable 1 using the through-hole transformer 9. When the through-hole transformer 9 is heated to the set temperature, the through-hole transformer 9 is closed. At this time, the temperature information of the insulation layer and the conductor of the submarine cable 1 can be monitored respectively by the first temperature probe 5 and the second temperature probe 6; when analyzing the vibration characteristics of the submarine cable 1, the flow generation system 3 is turned on to generate water flow, and the strain data of the submarine cable 1 under the action of uniform flow or oscillating flow is monitored by the fiber optic grating sensor 8, and the vortex-induced vibration response of the submarine cable 1 is obtained by computer processing; when analyzing the electromagnetic transient characteristics of the submarine cable 1, an overvoltage is generated on the conductor of the submarine cable 1 by the lightning surge generator 14, and the overvoltage waveform and the voltage waveform induced by the shielding layer of the submarine cable 1 are monitored by the oscilloscope 10, and the electromagnetic transient characteristics of the submarine cable 1 at this time are recorded. After the experiment, the flow generation system 3 is turned off, and the submarine cable 1 is allowed to cool naturally.

[0075] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0076] 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 application to the forms disclosed herein. Although multiple 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 submarine power cable multi-physics field coupling experimental platform, characterized in that: These include, Reservoirs, A submarine cable passing through the reservoir, A lifting bracket is arranged in the water reservoir and can lift and lower the submarine cable to form a partially suspended section. a flow-generating system, which is arranged in the water reservoir to generate a uniform flow and an oscillating flow toward the local suspended section, a first temperature probe for measuring a first temperature of an insulation layer of the submarine cable of the local suspended section, a second temperature probe measuring a second temperature of the conductor of the partially suspended segment, a fiber grating sensor for measuring the strain parameters of the local suspended segment when it oscillates in water, An ultrasonic flow meter is arranged in the water reservoir to measure the flow velocity, A through-hole transformer is arranged around the submarine cable outside the reservoir to pass current through the submarine cable by electromagnetic induction. a lightning surge generator connected to a submarine cable outside the reservoir to generate an overvoltage on a conductor of the submarine cable, An oscilloscope is connected to the submarine cable outside the water reservoir to monitor the waveform of the overvoltage and the voltage waveform induced by the shielding layer of the submarine cable.

2. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: Preferably, it also includes a computer connected to the flow generation system and the fiber grating sensor.

3. The submarine power cable multi-physics field coupling experimental platform according to claim 2, characterized in that: The computer is connected to the first temperature probe, the second temperature probe, the ultrasonic flow meter, the through-core transformer and the lightning surge generator.

4. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: The flow-generating system generates a uniform flow with a maximum velocity of 4 m / s and an oscillating flow with a peak velocity of 2 m / s in the reservoir.

5. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: The angle between the flow direction and the wave direction of the oscillating flow varies between 0-90°.

6. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: The lifting range of the lifting rod bracket is 0.5 to 1.5 m, and a buffer layer is provided between the lifting bracket and the submarine cable.

7. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: The second temperature probe is buried at a depth of 10 mm in the conductor of the submarine cable.

8. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: The velocity measurement range of the ultrasonic flow meter is 0~5 m / s, the velocity measurement error is within 0.001 m / s, and the maximum sampling frequency is 70 Hz.

9. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: The measuring range of the fiber Bragg grating sensor is ±1500 με, the central working wavelength range is 1525-1560 nm, and the lightning surge generator can generate a standard lightning wave waveform of 1.2 / 50us, with a voltage peak of 5 kV and a current peak of 2.5 kA.

10. The submarine power cable multi-physics field coupling experimental platform according to claim 1, characterized in that: The maximum current applied to the through-hole transformer is 2500 A for temperature rise test and unbalance detection.

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