Submarine cable temperature rise experiment platform considering complex laying conditions

Abstract

The invention discloses a submarine cable temperature rise experiment platform considering complex laying conditions. In the platform, an experiment cable and a second cable comprise conductors, insulation shields and sheaths, an air section experiment cable extends from a land cable terminal, a direct burial section experiment cable is directly buried in the ground from the tail end of the air section cable, and the direct burial section experiment cable further comprises a pipe penetrating section cable which penetrates through a pipe and is buried in the ground. The seabed section experiment cable extends into water from the tail end of the direct burial section cable, and the tail end of the seabed section experiment cable is provided with a submarine cable terminal; the second cable is a whole loop and comprises a pipe penetrating section and a direct burial section. The current transformer is arranged on the experimental cable and the second cable to measure the current of the experimental cable and the second cable; the feed-through transformer is connected with the alternating current voltage regulator to output alternating current voltage to control voltage loaded on the experimental cable and the second cable; the thermocouple temperature measurement module comprises a thermocouple and a temperature acquisition module, wherein the thermocouple is connected with the conductor, the insulation shield and the sheath. The distributed optical fiber temperature sensor cooperates with the optical fiber to detect the temperature of the outer sheath of the experimental submarine cable in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature rise of high-voltage direct current submarine cables, in particular to a temperature rise experimental platform for submarine cables. Background Art

[0002] With the rapid development of offshore wind power technology, high-voltage direct current (HVDC) submarine cables have become increasingly widespread. Compared to terrestrial cables, submarine cables face a more complex installation environment, primarily due to the interplay of environmental factors such as seawater temperature, ocean current velocity, and soil thermal conductivity. These factors lead to significant variations in the thermal conductivity and heat dissipation conditions of submarine cables across different installation sections. Even under the same load, the current carrying capacity and temperature vary significantly across different installation sections. Therefore, to ensure safe operation of submarine cables and prevent insulation degradation and even failure due to localized overheating, it is necessary to experimentally test the temperature of different cable installation sections to study the temperature variations under fluctuating loads.

[0003] Current experimental platforms for submarine cable temperature testing focus on temperature rise tests using air as the primary laying method. These tests utilize a through-hole transformer to heat the cable, and a real-time temperature monitoring device is used to measure the cable's heat generation under current flow. The current reading when the cable conductor is heated and stabilized at 70°C is used as the cable's current carrying capacity under these conditions. Thermocouples are added to the cable to measure the internal conductor temperature, insulation shield temperature, and outer sheath temperature. This experimental platform measures the temperature of the submarine cable only under air-laying conditions. However, in actual projects, the proportion of submarine cable sections laid in air is relatively small, and air sections are not temperature-sensitive. Furthermore, the actual operating environment of submarine cables includes sections such as the seabed, air sections, and conduit sections. Therefore, establishing a temperature rise test platform solely for cables laid in air as the primary laying method cannot reflect the actual operating conditions of submarine cables. Temperature rise tests under other laying environments are needed.

[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 response to the shortcomings or defects of the existing technology, a temperature rise test platform for submarine cables is provided. By simulating the complex laying environment of submarine cables, the temperature change law of submarine cables during actual operation can be better obtained, providing data support for studying the temperature changes of submarine cables under different laying environments.

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

[0007] A temperature rise test platform for submarine cables includes: An experimental cable comprising a conductor, an insulating shield and a sheath, wherein the experimental cable includes, from an extending direction, Land cable terminal, an air segment cable extending from said land cable terminal, The direct buried cable segment is directly buried into the ground from the end of the air segment cable. The direct buried cable segment also includes a pipe-through cable segment buried in the ground. A seabed section cable extending from the end of the directly buried section cable into the water, the seabed section cable including a seabed section cable repair joint, the end of which is provided with a cable terminal; a current transformer, provided on the test cable and the second cable to measure the current of the test cable; A through-hole transformer connected to an AC voltage regulator to output an AC voltage to control the voltage applied to the experimental cable and the second cable; Distributed fiber optic temperature sensor, which works with optical fiber to detect the outer sheath temperature of the experimental submarine cable in real time; The second cable is laid side by side with the experimental cable. The second cable includes a conductor, an insulating shield, and a sheath. The second cable is divided into a direct buried section cable and a pipe-through section cable in the extension direction. A thermocouple temperature measurement module includes thermocouples connected to the conductor, insulation shield, and sheath of the second cable, and a temperature acquisition module. The submarine cable temperature rise test platform also includes a computer connected to the current transformer, feedthrough transformer, thermocouple temperature measurement module, and distributed fiber optic temperature sensors. Based on the collected data, the computer generates a temperature trend over time for each section of the test cable under different loads.

[0008] In the temperature rise test platform for submarine cables, the burial depth of the directly buried cable section is consistent with the water depth of the repair joint of the submarine cable on the seabed section.

[0009] In the temperature rise test platform for submarine cables, the burial depth of the direct buried section of the cable is 1m; the burial depth of the pipe-through section of the cable is 1m; and the water depth of the repair joint of the submarine cable in the seabed section is 1m.

[0010] In the temperature rise test platform for submarine cables, the air section cable includes a straight section and a curved section.

[0011] In the temperature rise test platform for submarine cables, the armor of the experimental cable and the second cable are stripped off, and the two cables are heated by a core transformer. Each group of thermocouples in the thermocouple temperature measurement module contains three thermocouples, which respectively test the internal conductor temperature, insulation shield temperature and outer sheath temperature of the second cable. The thermocouples are externally connected to a temperature acquisition module to measure and record the temperature of the measured parts in real time.

[0012] In the temperature rise test platform for submarine cables, optical fibers are wound around the outer surface of the test cable, and distributed optical fiber temperature sensors are connected to measure and record the temperature of the outer sheath in real time.

[0013] In the temperature rise test platform for submarine cables, load cycle testing is performed by adjusting the AC voltage regulator to output different voltages.

[0014] In the temperature rise test platform of the submarine cable, during the load cycle test, the maximum temperature of the conductor is greater than or equal to 70°C, and the temperature difference between the inside and outside of the cable insulation is Between 12K and 16K.

[0015] In the temperature rise test platform for submarine cables, the directly buried section of the cable includes a sea-land transition joint and a submarine cable soft joint.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention simulates a ±400 kV high-voltage DC submarine cable in a complex laying environment, which can better understand the temperature variation law of the submarine cable under different laying environments and obtain the temperature weak section of the submarine cable, providing data support for avoiding insulation aging caused by local overheating during the operation of the submarine cable.

[0017] 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 easier to understand, so that those skilled in the art can implement it according to the contents of the description, 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 embodiments of the present invention are illustrated below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.

[0019] In the attached figure: Figure 1 It is a structural schematic diagram of the present invention; Figure 2 This is a schematic diagram of a thermocouple temperature measurement module of the present invention; Figure 3 Schematic diagram of temperature changes over time in different laying sections of a submarine cable in the HL high-load experiment of the present invention; Figure 4 Schematic diagram of temperature changes over time in different laying sections of a submarine cable in the LC load cycle experiment of the present invention.

[0020] The present invention will be further explained below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0021] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. 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 set forth herein. Rather, 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.

[0022] 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 invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0023] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings. However, the accompanying drawings do not limit the embodiments of the present invention.

[0024] For better understanding, Figures 1 to 4 As shown, a temperature rise test platform for submarine cables includes: The test cable is composed of a conductor, an insulating shield and a sheath. The test cable includes, from the extension direction, Land cable terminal, an air segment cable extending from said land cable terminal, The direct buried cable segment is directly buried into the ground from the end of the air segment cable. The direct buried cable segment also includes a pipe-through cable segment buried in the ground. A seabed section cable extending from the end of the directly buried section cable into the water, the seabed section cable including a seabed section cable repair joint, the end of which is provided with a cable terminal; a current transformer, provided on the test cable to measure the current of the test cable and a second cable; A through-hole transformer connected to an AC voltage regulator to output an AC voltage to control the voltage applied to the experimental cable and the second cable; Distributed fiber optic temperature sensor, which works with optical fiber to detect the outer sheath temperature of the experimental submarine cable in real time; The second cable is laid side by side with the experimental cable. The second cable includes a conductor, an insulating shield, and a sheath. The second cable is divided into a direct buried section cable and a pipe-through section cable in the extension direction. The thermocouple temperature measurement module includes a thermocouple connected to the conductor, insulation shield and sheath of the second cable and a temperature acquisition module. The second cable forms an analog loop and can measure temperature in real time.

[0025] In a preferred embodiment of the temperature rise test platform for submarine cables, it also includes a computer connected to the current transformer, the through-hole transformer, the thermocouple temperature measurement module and the distributed optical fiber temperature sensor, which forms the temperature change trend of each laying section of the experimental cable under different loads over time based on the collected data.

[0026] In a preferred embodiment of the temperature rise test platform for submarine cables, the burial depth of the directly buried section of the cable is consistent with the water depth of the repair joint of the seabed section of the submarine cable.

[0027] In a preferred embodiment of the temperature rise test platform for submarine cables, the burial depth of the direct buried section of the cable is 1m; the burial depth of the pipe-through section of the cable is 1m; and the water depth of the repair joint of the seabed section of the submarine cable is 1m.

[0028] In a preferred embodiment of the temperature rise test platform for submarine cables, the air section cable includes a straight section and a curved section.

[0029] In a preferred embodiment of the temperature rise test platform for submarine cables, the armor of the second cable and the test cable is stripped off, the two cables are heated by a through-core transformer, and each group of thermocouples in the thermocouple temperature measurement module contains three thermocouples, which respectively test the internal conductor temperature, insulation shield temperature and outer sheath temperature of the second cable. The thermocouples are externally connected to a temperature acquisition module to measure and record the temperature of the measured parts in real time.

[0030] In a preferred embodiment of the temperature rise test platform for submarine cables, optical fibers are wound around the outer surface of the test cable, and distributed optical fiber temperature sensors are connected to measure and record the temperature of the outer sheath in real time.

[0031] In a preferred embodiment of the temperature rise test platform for submarine cables, a load cycle test is performed by adjusting an AC voltage regulator to output different voltages.

[0032] In the preferred embodiment of the temperature rise test platform for submarine cables, during the load cycle test, the maximum temperature of the conductor is greater than or equal to 70°C, and the temperature difference between the inside and outside of the cable insulation is Between 12K and 16K.

[0033] In a preferred embodiment of the temperature rise test platform for submarine cables, the directly buried section of the cable includes a sea-land transition joint and a submarine cable flexible joint.

[0034] In one embodiment, Figure 1 As shown in the figure, the temperature rise test platform consists of an experimental cable, a second cable, a submarine cable flexible joint, a sea-to-land transition joint, a submarine cable repair joint, a submarine cable terminal, a land cable terminal, a current transformer, an AC voltage regulator, a feedthrough transformer, a thermocouple temperature measurement module, a distributed fiber optic temperature sensor, and optical fiber. The current transformer is used to measure the current in the experimental cable and the second cable at this time; the AC voltage regulator is connected to the feedthrough transformer and controls the voltage applied to the experimental cable and the second cable by outputting an AC voltage; the thermocouple temperature measurement module consists of a thermocouple and a temperature acquisition device. Its structure and thermocouple arrangement are shown in the figure. Figure 2 As shown; a distributed fiber optic temperature sensor is used in conjunction with the optical fiber to monitor the outer sheath temperature of the experimental cable in real time. The specific model parameters of the experimental equipment are shown in Table 1. Direct burial involves burying the submarine cable underground at a depth of 1m; the conduit section involves direct burial of the submarine cable through a conduit at a depth of 1m; air-laid installation includes both straight and curved sections, and seawater-laid installation involves burying the submarine cable in water at a depth of 1m. DC cable temperature testing was conducted at the experimental site. The second cable's armor was stripped and heated through a through-hole transformer. Three sets of thermocouples, each containing three thermocouples, were added to different sections of the cable. Each set measured the second cable's internal conductor temperature, insulation shield temperature, and sheath temperature. The thermocouples were connected to a temperature acquisition module to measure and record the temperature of the measured area in real time. Optical fiber was wrapped around the outer surface of the experimental cable and connected to a distributed fiber optic temperature acquisition device to measure and record the outer sheath temperature in real time.

[0035] The experiment includes LC load cycle test and HL high load test. The applied test voltage, polarity and cycle days are shown in Table 2. During the experiment, by adjusting the size of the AC voltage regulator, different voltages are output to control the load size applied to the submarine cable. The change of voltage over time is shown in Table 2. Among them, U0 is the rated voltage of the submarine cable 400kV. The voltage pause time between the load cycle tests of different polarities is not less than 24h, and the load cycle does not stop. During the experiment, the AC power output by the through-hole transformer heats the conductor. In the LC load cycle test and the HL high cycle test, the maximum temperature of the conductor is greater than or equal to 70°C, and the temperature difference between the inside and outside of the cable insulation is The voltage and current values ​​for the daily cycle are shown in Table 3. Finally, the temperatures of the conductors, insulation shield, and sheath at the cable repair joints in the air, in the direct buried section, in the conduit section, and on the seabed section were recorded every 1 minute.

[0036] Table 1 Experimental equipment parameters

[0037] Table 2 Experimental voltage changes over time

[0038] Table 3 Experimental voltage and current changes over time

[0039] Temperature rise experiments were conducted on ±400 kV submarine cables in air, direct buried, piped, and seabed installations. The three sets of thermocouples in each installation were used to measure the temperature of the same cable structure, and the average of the final temperature measurement results was taken. Finally, in a high-load experiment, the temperature changes of the conductor, insulation shield, and sheath in different installations over time were shown in the figure below. Figure 3 In the load cycle test, the temperature changes of the conductor, insulation shield and sheath in different laying sections over time are shown in Figure 4 The ambient temperature is measured using an outdoor thermometer.

[0040] This invention enables precise measurement and analysis of temperature variations in submarine cables under different installation conditions. The experimental and secondary cables consist of conductors, insulation shields, and sheaths, and include different sections (e.g., air section, direct buried section, conduit section, and seabed section) to simulate the operating environment of actual submarine cables under complex installation conditions. This design facilitates comprehensive evaluation of the cable's thermal performance in various environments. Current transformers accurately measure the current in the experimental and secondary cables, while a through-hole transformer controls the voltage applied to the cables by connecting to an AC voltage regulator. This allows researchers to accurately adjust and monitor the cable's operating load and study its temperature variations under various load conditions. The thermocouple temperature measurement module includes thermocouples connected to the conductors, insulation shield, and sheath, enabling real-time temperature measurement and recording. Each set of three thermocouples ensures precise measurement of the temperature distribution within the cable structure, providing insight into the thermal behavior of each layer of the cable. Distributed fiber optic temperature sensors, used in conjunction with optical fibers, enable real-time monitoring of the outer sheath temperature. Compared to traditional point-type temperature sensors, fiber optic sensors provide continuous temperature information along the cable's length, significantly improving the spatial resolution and accuracy of temperature monitoring. The computer system connecting all sensors and equipment can generate time-varying temperature trends for each section of the experimental cable under different loads based on the collected data. This not only simplifies data processing but also allows researchers to more deeply analyze the cable's thermal performance under various operating conditions, providing a scientific basis for optimizing cable design and operation. By adjusting the AC voltage regulator's output voltage to different levels for load cycling testing, the long-term reliability of the cable can be evaluated under simulated operating conditions. In particular, setting the maximum conductor temperature to 70°C or higher and the temperature difference between the inside and outside of the cable insulation to between 12K and 16K helps determine the cable's performance limits under extreme conditions. Clearly defined experimental equipment parameters (such as the basic parameters of the feedthrough transformer, the temperature range and accuracy of the thermocouples, etc.), as well as a detailed scheme for the time-varying experimental voltage and current (Tables 2 and 3), ensure high repeatability and reliable results, facilitating cross-laboratory comparison and validation.

[0041] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0042] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application 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, alterations, additions, and sub-combinations thereof.

Claims

1. A temperature rise test platform for submarine cables, characterized in that: These include, An experimental cable comprising a conductor, an insulating shield and a sheath, wherein the experimental cable includes, from an extending direction, Land cable terminal, an air segment cable extending from said land cable terminal, The direct buried cable segment is directly buried into the ground from the end of the air segment cable. The direct buried cable segment also includes a pipe-through cable segment buried in the ground. A seabed section cable extending from the end of the directly buried section cable into the water, the seabed section cable including a seabed section cable repair joint, the end of which is provided with a cable terminal; a current transformer, provided on the test cable and the second cable to measure the current of the test cable; A feedthrough transformer connected to an AC voltage regulator to output an AC voltage to control the voltage applied to the experimental cable and the second cable; Distributed fiber optic temperature sensor, which works with optical fiber to detect the outer sheath temperature of the experimental submarine cable in real time; The second cable is laid side by side with the experimental cable. The second cable includes a conductor, an insulating shield, and a sheath. The second cable is divided into a direct buried section cable and a pipe-through section cable in the extension direction. The thermocouple temperature measurement module includes a thermocouple connected to the conductor, insulation shield and sheath of the second cable and a temperature acquisition module.

2. The temperature rise test platform for submarine cables according to claim 1, characterized in that: Preferably, it also includes a computer connected to the current transformer, the through-hole transformer, the thermocouple temperature measurement module and the distributed optical fiber temperature sensor, which forms the temperature change trend of each laying section of the experimental cable under different loads over time based on the collected data.

3. The temperature rise test platform for submarine cables according to claim 1, characterized in that: The burial depth of the direct buried section of the cable is consistent with the water depth of the seabed section of the submarine cable repair joint.

4. The temperature rise test platform for submarine cables according to claim 1, characterized in that: The burial depth of the direct buried section of the cable is 1m; the burial depth of the cable in the pipe section is 1m; the water depth of the repair joint of the submarine cable in the seabed section is 1m.

5. The temperature rise test platform for submarine cables according to claim 1, characterized in that: The air segment cable includes a straight segment and a curved segment.

6. The temperature rise test platform for submarine cables according to claim 1, characterized in that: The armor of the experimental cable and the second cable are stripped off, and the two cables are heated by a through-core transformer. Each group of thermocouples in the thermocouple temperature measurement module contains three thermocouples, which respectively test the internal conductor temperature, insulation shielding temperature and sheath temperature of the second cable. The thermocouples are externally connected to a temperature acquisition module to measure and record the temperature of the measured parts in real time.

7. The temperature rise test platform for submarine cables according to claim 1, characterized in that: Optical fiber is wrapped around the outer surface of the experimental cable, and a distributed optical fiber temperature sensor is connected to measure and record the temperature of the outer sheath in real time.

8. The temperature rise test platform for submarine cables according to claim 1, characterized in that: Load cycle test by adjusting the AC voltage regulator to output different voltages.

9. The temperature rise test platform for submarine cables according to claim 8, characterized in that: During the load cycle test, the maximum conductor temperature is greater than or equal to 70°C, and the temperature difference between the inside and outside of the cable insulation is Between 12K and 16K.

10. The temperature rise test platform for submarine cables according to claim 1, characterized in that: The directly buried section cable includes a sea-land transition joint and a submarine cable flexible joint.

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