Submarine cable non-uniform aging simulation and magnetic induction detection system

Abstract

The invention discloses a submarine cable non-uniform aging simulation and magnetic induction detection system. The system comprises (1) a submarine cable non-uniform aging simulation module under laboratory conditions; (2) a submarine cable power-on operation simulation module under laboratory conditions; and (3) a magnetic induction detection module for the non-uniformly aged submarine cable under the condition of live operation. The problem that the research on the uneven aging of submarine cable lines is difficult is solved, the research cost and complexity are greatly reduced, and the internal mechanism and characteristics of the uneven aging of submarine cables can be analyzed and grasped; and meanwhile, multi-point detection under the non-uniform aging condition can be completed, a new thought is provided for daily inspection of the submarine cable, and therefore the safety and stability of the submarine cable line are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment testing, and in particular to a system for simulating uneven aging of submarine cables and detecting magnetic induction. Background Technology

[0002] With the rapid development of urbanization, the demand for electricity has increased significantly. Power cables are a key component in transmitting electrical energy and play a vital role in modern society. Compared to overhead lines, power can be transmitted from power sources to where it is needed more efficiently, reliably, cleanly, and aesthetically pleasingly, supporting people's production and daily lives. Submarine cables are cables laid on the seabed for power transmission and data communication. In recent years, with the advancement of the integrated energy internet and the construction of new power systems, the number of marine power transmission projects, mainly AC submarine cables, in my country's coastal and near-shore areas has been increasing, and the length of submarine cables in operation is growing daily, highlighting the growing importance of submarine cable lines.

[0003] Submarine cables have high voltage levels, large transmission capacities, and operate in complex environments. For terrestrial cables, the insulation aging is often uniform and consistent due to the relatively uniform burial environment. Unlike terrestrial cables, submarine cables are much longer, and their laying environment changes as they extend, traversing different sections such as land, shallow water, and deep water. The land section is the transition zone from underwater to land and is the bottleneck for the entire line's current carrying capacity. The large temperature variations in this section are a significant factor accelerating the thermal aging process of the insulation. Insulation aging is less likely to occur in the shallow and deep water sections of submarine cables because the seabed is generally relatively stable, with relatively low temperatures and relatively constant water quality conditions that help slow down the aging process. This leads to uneven aging in submarine cables. On the one hand, since most sections of submarine cables are underwater, daily maintenance and inspection are difficult, and underwater repair requires advanced technology. On the other hand, most submarine cables are still in their initial operational phase and are in good condition. Therefore, there is currently limited research on uneven aging of submarine cables in operation. With the emergence of problems caused by uneven aging of submarine cables in recent years, simulating uneven aging of submarine cables and developing a targeted detection system is beneficial for studying and understanding the characteristics of uneven aging of submarine cables and expanding the means of detecting live submarine cables. This has important practical significance and application value. Summary of the Invention

[0004] The purpose of this invention is to provide a system for simulating and detecting uneven aging of submarine cables using magnetic induction. The system utilizes a heating cable to accelerate thermal aging by wrapping both ends of a submarine cable sample, mimicking the thermal aging of the landing section. The remaining section of the cable sample is exposed to constant-temperature air to simulate the relatively stable temperature conditions in shallow and deep-sea sections. After the uneven aging process, a specific current is applied to the cable core based on its type, current-carrying capacity, and load to simulate actual operating conditions. Finally, a high-precision magnetic field sensor is used to measure the magnetic induction voltage signal at various points on the cable sample, forming a complete system for simulating and detecting uneven aging of submarine cables. The distortion of the induced voltage signal can be further used as an assessment basis for uneven aging of the cable.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a system for simulating and detecting uneven aging of submarine cables using magnetic induction, comprising:

[0006] (1) Simulation module for uneven aging of submarine cable under laboratory conditions: The two ends of the submarine cable sample are wrapped with heating and tracing tape to accelerate thermal aging and simulate the thermal aging of the landing section of the submarine cable; the remaining part of the middle section of the submarine cable sample is exposed to constant temperature air to simulate the relatively stable temperature conditions of the shallow and deep sea sections of the submarine cable; the heating temperature, heating time and the proportion of the two ends to the total length of the sample are controlled according to the actual operation and laying environment of the submarine cable.

[0007] (2) Submarine cable power-on operation simulation module under laboratory conditions: The power supply system consists of a voltage regulator and a high current generator, which form a circuit with the submarine cable sample with added stress cone and subjected to uneven aging process. According to the voltage level of the submarine cable and the operation and load conditions to be simulated, a certain amount of current is supplied to the core of the sample to simulate the actual operation state.

[0008] (3) Magnetic induction detection module for unevenly aged submarine cable under energized operation: Based on the energized operation simulation module for unevenly aged submarine cable, a high-precision inductive magnetic field sensor module is used to vertically attach to the outer surface of the submarine cable sample to measure the magnetic induction voltage signal at each point of the submarine cable sample, which serves as the basis for the study of uneven aging of submarine cable.

[0009] Furthermore, long spikes were driven into the copper cores at both ends of the submarine cable sample section for subsequent test wiring.

[0010] Furthermore, glass fiber heating tape or silicone rubber heating tape was used to wrap the corresponding parts at both ends of the submarine cable sample to simulate accelerated thermal aging test, and the heating temperature was controlled by the heating tape temperature controller.

[0011] Furthermore, during the simulation, the proportion of the aging section to the total length should not exceed 25%.

[0012] Furthermore, the high-precision inductive magnetic field sensor module is in the form of a probe, and its internal structure mainly includes two parts: a sensing element and an amplification circuit. The sensing element consists of a magnetic core and an induction coil. The amplification circuit is constructed using an amplification stage, a filtering stage, and a feedback stage.

[0013] Furthermore, the sensor core is made of permalloy 1J85, which has a high magnetic permeability, and the aspect ratio of the core is 20.

[0014] Furthermore, the diameter of the copper enameled wire of the induction coil is dcu=0.08 mm, the number of coil turns is N=11000, and the mass of the coil is 30 g.

[0015] Furthermore, the amplification stage employs a two-stage amplification configuration; the filtering stage first uses a high-pass filter circuit to filter out low-frequency signals, and then uses a low-pass filter circuit to filter out high-frequency signals; a path is led out from the output of the high-pass filter circuit to introduce a magnetic flux negative feedback loop to the induction coil; the main function of the two voltage followers is to act as buffer stages, reducing signal loss at the output impedance of the previous stage when the input impedance of the subsequent stage is low, thereby improving the circuit's signal output capability.

[0016] Furthermore, the vertical close contact with the outer surface of the submarine cable sample means that the inductive magnetic field sensor probe is closely attached to the outer surface of the submarine cable sample, and is perpendicular to the axial direction of the submarine cable sample and the cross-section of the outer surface of the submarine cable sample at 90°.

[0017] The beneficial effects of this invention are:

[0018] This invention provides a system for simulating and detecting uneven aging of submarine cables using magnetic induction. Establishing such a system is of great significance for studying and understanding the characteristics of uneven aging in submarine cables and for assessing their operational status. Specific beneficial effects of this invention include:

[0019] 1) Based on the actual laying environment and uneven aging of submarine cables, a laboratory simulation method for uneven aging of submarine cables is proposed. Submarine cables in operation are very long, and the vast majority are underwater. Even routine maintenance and underwater repair techniques present many challenges, making it difficult to implement and conduct research on uneven thermal aging of in-operation submarine cables. This invention opens up a simulation research path for uneven thermal aging of submarine cables. By controlling the heating temperature, heating time, and the proportion of aging sections at both ends, various situations of uneven aging in actual submarine cables can be simulated. From the perspective of experimental simulation, this solves the problem of the difficulty in studying uneven aging of submarine cable lines, greatly reduces research costs and complexity, and helps to analyze and grasp the internal mechanism and characteristics of uneven aging of submarine cables.

[0020] 2) Based on the simulation of uneven aging of submarine cables, this paper simulates the energized operation of submarine cables and proposes a magnetic induction detection system with a high-precision magnetic field sensor as its core. On one hand, the inductive magnetic field sensor probe measures the induced voltage waveform at various points on the submarine cable, which is simple to operate and portable. On the other hand, the sensor has good detection accuracy and anti-interference performance, enabling multi-point detection under uneven aging conditions. This submarine cable magnetic induction detection system expands the means of energized submarine cable detection, providing a new approach for daily inspection of submarine cables, thereby ensuring the safety and stability of submarine cable lines. Attached Figure Description

[0021] The various advantages and benefits that this technology brings to those working in the field of electrical equipment condition monitoring are illustrated through the detailed description of the following preferred embodiments. The following figures are for illustrative purposes only and should not be considered as limitations of the invention. Furthermore, in all figures, the same reference numerals represent the same components. In the figures:

[0022] Figure 1 A schematic diagram of the environment for laying submarine cables;

[0023] Figure 2 A schematic diagram of a method for simulating uneven aging of submarine cables;

[0024] Figure 3 Circuit diagram for simulated operation test of submarine cable;

[0025] Figure 4 This is a diagram of the internal structure of an inductive magnetic field sensor.

[0026] Figure 5 Example of an induced voltage waveform measured by a magnetic field sensor;

[0027] Figure 6 This is a schematic diagram of a magnetic induction detection system for unevenly aging submarine cables. Detailed Implementation

[0028] The illustrative embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The drawings are used to illustrate exemplary embodiments of the invention, but it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. The provided embodiments are intended to assist the reader in a more comprehensive understanding of the invention and to fully convey the content of the invention to those skilled in the art.

[0029] In a specific embodiment of the invention, glass fiber heating tape is used to wrap both ends of the submarine cable sample for accelerated thermal aging testing, while the middle section is exposed to constant-temperature air. This simulates the uneven thermal aging of the submarine cable, where the landing section is prone to aging while the deep / shallow sea sections are less prone to aging. For the unevenly aged submarine cable, this embodiment uses a voltage regulator combined with a high-current generator to form a power system, supplying operating current to the core of the submarine cable sample to simulate the actual operating state of the submarine cable. A high-precision inductive magnetic field sensor is designed as the core of the magnetic induction detection system, enabling non-invasive live detection of the induced voltage signal at various points on the unevenly aged submarine cable. The specific steps are as follows:

[0030] 1. Simulation of uneven aging of submarine cables under laboratory conditions

[0031] Figure 1 This diagram illustrates the environment in which submarine cables are laid. The landing sections at both ends of the submarine cable line are the bottleneck sections for the entire line's current carrying capacity and are also the high-risk areas for insulation thermal aging. In contrast, the shallow and deep-sea sections of the submarine cable located underwater have lower and more stable environmental temperatures, making them less prone to overall aging. Figure 2 A schematic diagram of a method for simulating non-uniform aging of submarine cables is shown. Specific requirements for simulating non-uniform aging of submarine cables under laboratory conditions are as follows:

[0032] (1) Considering that submarine cables are relatively thick and the outer layer of the cable is difficult to peel off, it is considered to drive 4cm long nails into the copper cores at both ends of the submarine cable sample section to a depth of 2cm for subsequent test wiring;

[0033] (2) For the simulation of the aging section of the submarine cable, glass fiber heating tape or silicone rubber heating tape should be used to wrap the corresponding parts at both ends to conduct accelerated thermal aging test simulation, and the heating temperature should be controlled by the heating tape temperature controller.

[0034] (3) For the simulation of non-aging sections of submarine cables, the corresponding middle section of the submarine cable should be exposed to constant temperature air without accelerated thermal aging to simulate the relatively stable temperature conditions of shallow and deep sea sections of submarine cables.

[0035] (4) Maintain a constant ambient air temperature of 20°C in the middle section of the submarine cable, based on the actual ambient temperature of the shallow / deep sea section. The temperature control can be adjusted according to the simulated marine environment.

[0036] (5) Considering that the maximum allowable operating temperature of power cables is 90℃, the heating band temperature can be set to 90℃, 105℃, 120℃, 135℃, etc., according to actual needs during the accelerated aging simulation process. The heating temperature should not exceed 150℃.

[0037] (6) Insulation aging at different degrees and stages can be simulated by controlling the heating time of the heating belt. Usually, the aging time of the geometric series is used to study the changes in various aspects of performance during the aging process.

[0038] (7) By controlling the proportion of the accelerated aging section at both ends of the submarine cable sample to the total length, the aging conditions under different laying conditions are simulated. Considering the actual laying conditions, the proportion of the aging section to the total length should not exceed 25% during the simulation process; otherwise, it will lose its reference value to a large extent.

[0039] (8) When using heating tape to wrap submarine cables for accelerated aging, the heating tape should be as close to the surface of the submarine cable as possible, and the heating tape should not overlap during the wrapping process, so as to simulate the overall insulation aging of the aging section to the greatest extent.

[0040] 2. Simulation of submarine cable energization operation under laboratory conditions

[0041] After simulating the uneven aging process of the submarine cable, the energized operation of the submarine cable was simulated under laboratory conditions. Figure 3 This is a circuit diagram for a simulated operation test of a submarine cable. A voltage regulator combined with a high-current generator is used to supply operating current to the core of the submarine cable sample, simulating the actual operating conditions of the cable. The power supply system includes a 220V AC power supply, a voltage regulator, and a high-current generator.

[0042] (1) The input voltage of the voltage regulator is 220 V, and the output voltage range is 0-250 V. The output voltage is controlled by a knob.

[0043] (2) The high current generator is connected to the voltage regulator. The input voltage is the output voltage of the voltage regulator. When the input voltage of the high current generator changes, its output current will also change accordingly. By controlling the voltage regulator knob, the output secondary current of the high current generator is in the range of 0-100 A.

[0044] (3) This experiment is an applied current test. The high current generator and the submarine cable sample are connected by bare copper wire with strong current carrying capacity.

[0045] (4) By controlling the voltage regulator knob, a certain amount of current, such as 30A or 50A, is supplied to the core of the submarine cable to simulate the energized operation of the submarine cable.

[0046] 3. Design of a high-precision inductive magnetic field sensor

[0047] Inductive magnetic sensors mainly consist of two parts: the sensing element and the amplification circuit. The magnetic core and the induction coil constitute the sensing element of the sensor. The internal structure of an inductive magnetic field sensor is as follows: Figure 4As shown. Inductive magnetic sensors measure magnetic fields by utilizing the change in magnetic flux passing through the inside of a coil, generating an induced electromotive force. During measurement, the shape and position of the coil loop remain stationary, thus it is used to measure changing magnetic fields. The measured magnetic flux is perpendicular to the magnetic flux of the magnetic core cross-section.

[0048] (1) For the sensor core, a material with high permeability is selected. Here, Permalloy 1J85 is used, and the optimal aspect ratio of the core is determined to be 20.

[0049] (2) For the induction coil, noise and coil quality optimization were performed. The diameter of the copper enameled wire was determined to be dcu=0.08 mm, the number of coil turns N=11000, and the mass of the coil was 30 g;

[0050] (3) For the amplifier circuit, amplification, filtering, and feedback are used to construct it. The amplification stage adopts a two-stage amplification form; the filtering stage first uses a high-pass filter circuit to filter out low-frequency signals, and then uses a low-pass filter circuit to filter out high-frequency signals; a path is led out from the output of the high-pass filter circuit to introduce a magnetic flux negative feedback stage to the induction coil; the main function of the two voltage followers is to act as a buffer stage to reduce the signal loss on the output impedance of the previous stage when the input impedance of the subsequent stage is low, thereby improving the circuit's signal output capability.

[0051] (4) The signal detected by the high-precision inductive magnetic field sensor is a magnetic induction voltage signal, and the waveform example is as follows. Figure 5 .

[0052] 4. Magnetic induction detection of unevenly aging submarine cables

[0053] Figure 6 A schematic diagram of a magnetic induction detection system for unevenly aging submarine cables is presented. A data acquisition system and a data analysis and processing system are added to a submarine cable energized operation simulation system. The data acquisition system consists of a magnetic field sensor probe, a coaxial cable, and an oscilloscope. The induced voltage signal at various points on the submarine cable sample is measured using an inductive magnetic field sensor probe, and the signal waveform is displayed on the oscilloscope. The oscilloscope is connected to a computer, where waveform distortion caused by uneven aging of the submarine cable is analyzed and studied.

[0054] (1) During the test, the inductive magnetic field sensor probe should be in close contact with the outer surface of the submarine cable sample and be perpendicular to the submarine cable axis and the outer surface section of the submarine cable at 90°.

[0055] (2) Based on actual research needs, a detection point is set at regular intervals. In this embodiment, a detection point is set every 200 mm. All detection points should be in a straight line along the axial direction of the submarine cable.

[0056] Thus, combined with the simulated aging process, a complete system for simulating and detecting uneven aging of submarine cables and magnetic induction is formed. The distortion of the induced voltage signal can be further used as an assessment basis for uneven aging of submarine cables. Experimental simulation was used to study the uneven thermal aging problem of submarine cables and to conduct non-invasive detection research on magnetic field signals. This provides a research approach for the uneven thermal aging problem of submarine cables beyond software simulation and proposes a targeted live-line detection method.

Claims

1. A system for simulating uneven aging of submarine cables and detecting magnetic induction, characterized in that... The system includes: (1) Simulation module for uneven aging of submarine cable under laboratory conditions: The two ends of the submarine cable sample are wrapped with heating and tracing tape to accelerate thermal aging and simulate the thermal aging of the landing section of the submarine cable; the remaining part of the middle section of the submarine cable sample is exposed to constant temperature air to simulate the relatively stable temperature conditions of the shallow and deep sea sections of the submarine cable; the heating temperature, heating time and the proportion of the two ends to the total length of the sample are controlled according to the actual operation and laying environment of the submarine cable. (2) Submarine cable power-on operation simulation module under laboratory conditions: The power supply system consists of a voltage regulator and a high current generator, which form a circuit with the submarine cable sample with added stress cone and subjected to uneven aging process. According to the voltage level of the submarine cable and the operation and load conditions to be simulated, a certain amount of current is supplied to the core of the sample to simulate the actual operation state. (3) Magnetic induction detection module for unevenly aged submarine cable under energized operation: Based on the energized operation simulation module for unevenly aged submarine cable, a high-precision inductive magnetic field sensor module is used to vertically attach to the outer surface of the submarine cable sample to measure the magnetic induction voltage signal at each point of the submarine cable sample, which serves as the basis for the study of uneven aging of submarine cable.

2. The system according to claim 1, characterized in that: Long spikes are driven into the copper cores at both ends of the submarine cable sample section for subsequent test wiring.

3. The system according to claim 1, characterized in that: The corresponding parts at both ends of the submarine cable sample were wrapped with glass fiber heating tape or silicone rubber heating tape to simulate accelerated thermal aging test, and the heating temperature was controlled by the heating tape temperature controller.

4. The system according to claim 1, characterized in that: During the simulation, the proportion of the aging section to the total length should not exceed 25%.

5. The system according to claim 1, characterized in that: The high-precision inductive magnetic field sensor module is in the form of a probe, and its internal structure mainly includes two parts: a sensing element and an amplification circuit. The sensing element consists of a magnetic core and an induction coil. The amplification circuit is constructed using an amplification stage, a filtering stage, and a feedback stage.

6. The system according to claim 5, characterized in that: The sensor core is made of permalloy 1J85, which has a high magnetic permeability, and the aspect ratio of the core is 20.

7. The system according to claim 5, characterized in that: The diameter of the copper enameled wire of the induction coil is dcu=0.08 mm, the number of coil turns is N=11000, and the mass of the coil is 30 g.

8. The system according to claim 5, characterized in that: The amplification stage employs a two-stage amplification configuration; the filtering stage first uses a high-pass filter circuit to filter out low-frequency signals, and then uses a low-pass filter circuit to filter out high-frequency signals; a path is led out from the output of the high-pass filter circuit to introduce a magnetic flux negative feedback loop to the induction coil; the main function of the two voltage followers is to act as buffer stages, reducing signal loss at the output impedance of the previous stage when the input impedance of the subsequent stage is low, thereby improving the circuit's signal output capability.

9. The system according to claim 1, characterized in that: The vertical close contact with the outer surface of the submarine cable sample means that the inductive magnetic field sensor probe is closely attached to the outer surface of the submarine cable sample, and is perpendicular to the axial direction and the outer surface cross-section of the submarine cable sample at 90°.

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