A high-voltage submarine cable prefabricated plug-in connection system and method

Abstract

The application discloses a high-voltage submarine cable prefabricated plug-in connection system, which comprises a prefabricated high-voltage submarine cable module, the high-voltage submarine cable module is composed of a high-voltage submarine cable and plug-in terminals at both ends of the high-voltage submarine cable, the plug-in terminals complete insulation assembly, sealing and high-voltage test with the high-voltage submarine cable in a factory; the system further comprises plug-in connectors, the plug-in connectors are composed of submarine cable terminal plugs and submarine cable terminal sockets, the submarine cable terminal plugs are integrated on the plug-in terminals, the submarine cable terminal sockets are preassembled on transformers and / or high-voltage switch cabinets GIS and / or converter valves and / or direct current field equipment; the cable core surface of the high-voltage submarine cable is provided with a space charge inhibiting layer, and the cable core periphery of the high-voltage submarine cable is coated with a polarity reversal resistant structure. The application can inhibit space charge density, reduce dielectric loss and local discharge risk.

Description

Technical Field

[0001] This invention relates to high-voltage submarine cables, and more particularly to a prefabricated plug-in connection system for high-voltage submarine cables. Background Technology

[0002] Traditional high-voltage submarine cable terminals require complex procedures such as insulation treatment and stress cone installation on the offshore converter station platform. Due to the harsh marine environment, the following problems exist:

[0003] Space charge accumulation: Under a DC electric field, traditional cross-linked polyethylene (XLPE) insulation materials are prone to the formation of space charge, leading to local electric field distortion (field strength can reach 30kV / mm) and causing insulation breakdown. Under an AC electric field, traditional high-voltage cross-linked polyethylene (XLPE) cables exhibit space charge accumulation, especially when there are defects in the insulation material or inhomogeneous interfaces. Charges temporarily accumulate in local areas, causing increased dielectric loss or partial discharge.

[0004] Insufficient tolerance to polarity reversal: For DC systems, the power fluctuations of offshore wind power cause frequent voltage polarity reversals, and traditional stress cone interfaces are prone to surface flashover (failure probability >20%).

[0005] High-voltage testing is difficult and time-consuming: offshore converter stations have limited operating space, harsh environment, and interference factors such as salt spray and humidity, making testing difficult and the results inconsistent.

[0006] Offshore installation is inefficient: on-site processes require vacuum treatment and manual installation, which takes a long time.

[0007] Low reliability: Impurities are easily introduced during on-site glue / gas injection, and there is a risk of gas leakage and partial discharge during long-term operation. Summary of the Invention

[0008] The purpose of this invention is to provide a prefabricated plug-in connection system for high-voltage submarine cables, which has a nano-modified insulation layer that can suppress space charge density, reduce dielectric loss, and reduce the risk of partial discharge.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A prefabricated pluggable connection system for high-voltage submarine cables includes a prefabricated high-voltage submarine cable module, which consists of a high-voltage submarine cable and pluggable terminals at both ends of the high-voltage submarine cable. The pluggable terminals undergo insulation assembly, sealing, and high-voltage testing with the high-voltage submarine cable at the factory. The system also includes a pluggable connector, which consists of a submarine cable terminal plug and a submarine cable terminal socket. The submarine cable terminal plug is integrated onto the pluggable terminal, and the submarine cable terminal socket is pre-installed on transformers and / or high-voltage switchgear GIS and / or converter valves and / or DC field equipment. The core surface of the high-voltage submarine cable has a space charge suppression layer, and the core is surrounded by a polarity reversal withstand structure.

[0011] In the aforementioned prefabricated plug-in connection system for high-voltage submarine cables, the high-voltage submarine cable is a high-voltage DC submarine cable. The space charge suppression layer is composed of cross-linked polyethylene doped with nano-boron nitride. The nano-boron nitride is surface modified by hydroxylation, and its interfacial bonding strength with the cross-linked polyethylene matrix is ​​≥15MPa. The boron nitride has a mass fraction of 0.8%-1.2% and a particle size of 50-100nm, and is used for insulation and suppression of space charge.

[0012] In the aforementioned prefabricated plug-in connection system for high-voltage submarine cables, the high-voltage submarine cable is a high-voltage AC submarine cable, and the space charge suppression layer is a ternary ethylene propylene rubber insulation layer doped with nano-Al2O3, with an Al2O3 mass fraction of 2%-3%, used for insulation and reducing dielectric loss.

[0013] In the aforementioned prefabricated plug-in connection system for high-voltage submarine cables, the polarity reversal tolerance structure is a three-layer composite stress cone, comprising an inner layer of plasma-sprayed silicon carbide, a middle layer of graphene paper, and an outer layer of fluororubber matrix.

[0014] In the aforementioned prefabricated pluggable connection system for high-voltage submarine cables, the connection between the high-voltage submarine cable and the pluggable terminal is sealed by a dynamic compensation sealing component. This dynamic compensation sealing component is a magnetic fluid-titanium alloy bellows composite sealing structure. The magnetic fluid is a mixture of Fe3O4 nanoparticles and perfluoropolyether oil at a ratio of 20 wt%, with the Fe3O4 nanoparticles having a particle size of 10 nm. The leakage rate of the magnetic fluid-titanium alloy bellows composite sealing structure is ≤1×10⁻⁶. -9 Pa·m 3 / s.

[0015] In the aforementioned prefabricated plug-in connection system for high-voltage submarine cables, the intelligent monitoring unit consists of a distributed fiber Bragg grating sensor embedded within the high-voltage submarine cable. One fiber Bragg grating sensor is arranged every 0.5m along the axial direction of the high-voltage submarine cable. The spatial resolution of the distributed fiber Bragg grating sensor is 0.1m, and it is used to monitor the temperature, strain, and partial discharge of the high-voltage submarine cable.

[0016] In the aforementioned prefabricated plug-in connection system for high-voltage submarine cables, the high-voltage submarine cable modules are prefabricated using the following method:

[0017] Step S001: Install a composite stress cone in the workshop. The composite stress cone is pre-filled with SF6 / N2 mixed gas at a pressure of 0.4 MPa.

[0018] Step S002: Conduct high voltage withstand test, lightning impulse test, and partial discharge test on the prefabricated module;

[0019] Step S003: Using a deck-rail robot equipped with a laser-vision positioning system, align the submarine cable terminal plug with the submarine cable terminal socket with a positioning accuracy of ±0.1mm; the deck-rail robot integrates laser-ultrasonic positioning and a hydraulic insertion mechanism with a positioning accuracy of ±0.05mm and an insertion time of ≤2 hours;

[0020] Step S004: Hydraulic drive insertion, bellows compensation for ±15mm axial displacement, magnetic fluid seal for lateral vibration, amplitude ±3mm, frequency ≤20Hz;

[0021] Step S005: After power-on, the data is monitored in real time by distributed fiber optic sensors and uploaded to the land-based monitoring platform.

[0022] In the aforementioned prefabricated plug-in connection system for high-voltage submarine cables, the plug-in interface of the submarine cable terminal plug and the submarine cable terminal socket is provided with three layers of nonlinear conductive silicone rubber, with an inner layer of 15wt% carbon black concentration, a middle layer of 10wt% carbon black concentration, and an outer layer of 5wt% carbon black concentration, and a field strength dependence coefficient β = 0.05.

[0023] Compared with existing technologies, this invention can suppress space charge density, reduce dielectric loss, and mitigate the risk of partial discharge. Through collaborative innovation in materials, structure, monitoring, and testing, it suppresses space charge accumulation, reduces dielectric loss, partial discharge, and insulation aging in high-voltage AC submarine cables, improves the polarity reversal tolerance of high-voltage DC submarine cables, and adapts to the special operating conditions of deep-sea offshore converter stations. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the system connection relationship according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the connection relationship in the first application mode of the present invention;

[0026] Figure 3 This is a schematic diagram of the connection relationship in the second application mode of the present invention;

[0027] Figure 4 This is a schematic diagram of the connection relationship in the third application mode of the present invention;

[0028] Figure 5 This is a schematic diagram of the cross-sectional structure of a three-layer composite stress cone.

[0029] Reference numerals: 1-High-voltage submarine cable, 2-Plug-in terminal, 3-Submarine cable terminal plug, 4-Submarine cable terminal socket, 5-Transformer, 6-High-voltage switchgear GIS, 7-Converter valve, 8-DC field equipment, 9-Three-layer composite stress cone, 91-Inner layer plasma-sprayed silicon carbide, 92-Middle layer graphene paper, 93-Outer layer fluororubber matrix.

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0031] Embodiment 1 of the present invention: A prefabricated pluggable connection system for high-voltage submarine cables, comprising a prefabricated high-voltage submarine cable module, the high-voltage submarine cable module consisting of a high-voltage submarine cable 1 and pluggable terminals 2 at both ends of the high-voltage submarine cable 1, wherein the pluggable terminals 2 are insulated, sealed and tested with the high-voltage submarine cable in the factory; it also includes a pluggable connector, which consists of a submarine cable terminal plug 3 and a submarine cable terminal socket 4, the submarine cable terminal plug 3 being integrated on the pluggable terminal 2, and the submarine cable terminal socket 4 being pre-installed on a transformer 5 and / or a high-voltage switchgear GIS 6 and / or a converter valve 7 and / or a DC field device 8; the pluggable interface of the submarine cable terminal plug 3 and the submarine cable terminal socket 4 is provided with three layers of nonlinear conductive silicone rubber, the inner layer having a carbon black concentration of 15wt%, the middle layer 10wt%, and the outer layer 5wt%, with a field strength dependence coefficient β = 0.05; the surface of the cable core of the high-voltage submarine cable 1 has a space charge suppression layer, and the periphery of the cable core of the high-voltage submarine cable 1 is covered with a polarity reversal tolerance structure. The polarity reversal tolerance structure is a three-layer composite stress cone 9, comprising an inner layer of plasma-sprayed silicon carbide 91SiC (thickness 200μm, conductivity 10-3S / m), a middle layer of graphene paper 92 (thickness 0.1mm, tensile modulus 1TPa), and an outer layer of fluororubber matrix 93 (dielectric constant ε_r = 3.2).

[0032] The high-voltage submarine cable 1 is a high-voltage DC submarine cable. The space charge suppression layer is composed of cross-linked polyethylene doped with nano-boron nitride. The nano-boron nitride is surface modified by hydroxylation, and the interfacial bonding strength with the cross-linked polyethylene matrix is ​​≥15MPa. The boron nitride mass fraction is 1.0%, and the particle size is 50-100nm. After extrusion molding, the charge density is verified by the electroacoustic pulse method (PEA) and cured to form an insulation layer with a thickness of 25mm. It is used for insulation and suppression of space charge.

[0033] The connection between the high-voltage submarine cable 1 and the pluggable terminal 2 is sealed by a dynamic compensation sealing assembly. This assembly is a magnetic fluid-titanium alloy bellows composite sealing structure. The magnetic fluid is a mixture of Fe3O4 nanoparticles and perfluoropolyether oil at a ratio of 20 wt%, with the Fe3O4 nanoparticles having a particle size of 10 nm. The leakage rate of the magnetic fluid-titanium alloy bellows composite sealing structure is ≤1×10⁻⁶. -9 Pa·m 3 / s.

[0034] As an intelligent monitoring unit, the high-voltage submarine cable 1 is embedded with a distributed fiber Bragg grating sensor. One fiber Bragg grating sensor is arranged every 0.5m along the axial direction of the high-voltage submarine cable 1. The spatial resolution of the distributed fiber Bragg grating sensor is 0.1m, which is used to monitor the temperature, strain and partial discharge of the high-voltage submarine cable 1.

[0035] Example 2: A prefabricated pluggable connection system for high-voltage submarine cables includes a prefabricated high-voltage submarine cable module, which consists of a high-voltage submarine cable 1 and pluggable terminals 2 at both ends of the high-voltage submarine cable 1. The pluggable terminals 2 are insulated, sealed, and subjected to high-voltage testing with the high-voltage submarine cable in the factory. The system also includes a pluggable connector, which consists of a submarine cable terminal plug 3 and a submarine cable terminal socket 4. The submarine cable terminal plug 3 is integrated onto the pluggable terminal 2, and the submarine cable terminal socket 4 is pre-installed on a transformer 5 and / or a high-voltage switchgear GIS 6 and / or a converter valve 7 and / or a DC field device 8. The pluggable interface of the submarine cable terminal plug 3 and the submarine cable terminal socket 4 is provided with three layers of nonlinear conductive silicone rubber, with an inner layer of 15wt% carbon black concentration, a middle layer of 10wt%, and an outer layer of 5wt%, and a field strength dependence coefficient β = 0.05. The surface of the core of the high-voltage submarine cable 1 has a space charge suppression layer, and the core of the high-voltage submarine cable 1 is surrounded by a polarity reversal tolerance structure. The polarity reversal tolerance structure is a three-layer composite stress cone 9, comprising an inner layer of plasma-sprayed silicon carbide 91SiC (thickness 200μm, conductivity 10-3S / m), a middle layer of graphene paper 92 (thickness 0.1mm, tensile modulus 1TPa), and an outer layer of fluororubber matrix 93 (dielectric constant ε_r = 3.2).

[0036] The high-voltage submarine cable 1 is a high-voltage AC submarine cable. The space charge suppression layer is a ternary ethylene propylene rubber insulation layer doped with nano-Al2O3, with an Al2O3 mass fraction of 2.5%, and the dielectric loss is tested (≤0.02% at 1kHz); it is used for insulation and reducing dielectric loss.

[0037] The connection between the high-voltage submarine cable 1 and the pluggable terminal 2 is sealed by a dynamic compensation sealing assembly. This assembly is a magnetic fluid-titanium alloy bellows composite sealing structure. The magnetic fluid is a mixture of Fe3O4 nanoparticles and perfluoropolyether oil at a ratio of 20 wt%, with the Fe3O4 nanoparticles having a particle size of 10 nm. The leakage rate of the magnetic fluid-titanium alloy bellows composite sealing structure is ≤1×10⁻⁶. -9 Pa·m 3 / s.

[0038] As an intelligent monitoring unit, the high-voltage submarine cable 1 is embedded with a distributed fiber Bragg grating sensor. One fiber Bragg grating sensor is arranged every 0.5m along the axial direction of the high-voltage submarine cable 1. The spatial resolution of the distributed fiber Bragg grating sensor is 0.1m, which is used to monitor the temperature, strain and partial discharge of the high-voltage submarine cable 1.

[0039] The high-voltage submarine cable prefabrication plug-in connection system described in the above embodiments uses the following method for prefabrication of the high-voltage submarine cable module:

[0040] Step S001: Install the composite stress cone 9 in the workshop using a robot. The composite stress cone 9 is pre-filled with SF6 / N2 mixed gas (volume ratio 3:7, gas pressure 0.4MPa) and the gas pressure of the mixed gas is 0.4MPa; it is then sealed in a protective cylinder filled with dry nitrogen.

[0041] Step S002: Conduct high voltage withstand test, lightning impulse test, partial discharge test, polarity reversal test (1000 times), and other electrical and mechanical tests on the prefabricated module;

[0042] Step S003: Using a deck-rail robot equipped with a laser-vision positioning system, the submarine cable terminal plug 3 and the submarine cable terminal socket 4 are aligned with a positioning accuracy of ±0.1mm; the deck-rail robot integrates laser-ultrasonic positioning and hydraulic insertion mechanism, with a positioning accuracy of ±0.05mm and an insertion time of ≤2 hours;

[0043] Step S004: Hydraulic drive insertion, bellows compensation for ±15mm axial displacement, magnetohydrodynamic seal lateral vibration, amplitude ±3mm, frequency ≤20Hz; seal performance is tested by helium mass spectrometry leak detector, and after passing the test, it is packaged and transported.

[0044] Step S005: After power-on, the data is monitored in real time by distributed fiber optic sensors and uploaded to the land-based monitoring platform.

[0045] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0046] 1. Nano-modified insulating layer: suppresses space charge density, reduces dielectric loss and the risk of partial discharge;

[0047] 2. Composite stress cone: withstands ±500kV polarity reversal 1000 times;

[0048] 3. Dynamic sealing: compensates for ±15mm displacement, leakage rate ≤1×10 -9 Pa·m 3 / s;

[0049] 4. Intelligent Interlocking: Deck rail robot integrating laser-ultrasonic positioning and hydraulic interlocking mechanism.

[0050] Installation of a single circuit was completed in 2 hours;

[0051] 5. Factory high-voltage test: All electrical and mechanical verifications are completed before leaving the factory.

[0052] 6. Factory prefabrication and standardization: Submarine cable modules are prefabricated in a cleanroom.

Claims

1. A prefabricated pluggable connection system for high-voltage submarine cables, characterized in that, It includes a prefabricated high-voltage submarine cable module, which consists of a high-voltage submarine cable (1) and pluggable terminals (2) at both ends of the high-voltage submarine cable (1). The pluggable terminals (2) are insulated, sealed and tested with the high-voltage submarine cable in the factory. It also includes a plug-in connector, which consists of a submarine cable terminal plug (3) and a submarine cable terminal socket (4). The submarine cable terminal plug (3) is integrated on the plug-in terminal (2), and the submarine cable terminal socket (4) is pre-installed on the transformer (5) and / or the high-voltage switchgear GIS (6) and / or the converter valve (7) and / or the DC field equipment (8). The core surface of the high-voltage submarine cable (1) has a space charge suppression layer, and the core of the high-voltage submarine cable (1) is covered with a polarity reversal tolerance structure. The high-voltage submarine cable (1) is a high-voltage DC submarine cable, and the space charge suppression layer is composed of cross-linked polyethylene doped with nano boron nitride; or the high-voltage submarine cable (1) is a high-voltage AC submarine cable, and the space charge suppression layer is a ternary ethylene propylene rubber insulation layer doped with nano Al2O3. The polarity reversal tolerance structure is a three-layer composite stress cone (9), comprising an inner layer of plasma-sprayed silicon carbide (91), a middle layer of graphene paper (92), and an outer layer of fluororubber matrix (93).

2. The prefabricated plug-in connection system for high-voltage submarine cables according to claim 1, characterized in that, The nano-boron nitride is surface-modified by hydroxylation, and has an interfacial bonding strength with the cross-linked polyethylene matrix of ≥15MPa. The boron nitride mass fraction is 0.8%-1.2%, and the particle size is 50-100nm. It is used for insulation and suppression of space charge.

3. The prefabricated plug-in connection system for high-voltage submarine cables according to claim 1, characterized in that, Al2O3 has a mass fraction of 2%-3% and is used for insulation and reducing dielectric loss.

4. The prefabricated pluggable connection system for high-voltage submarine cables according to claim 1, characterized in that, The connection between the high-voltage submarine cable (1) and the plug-in terminal (2) is sealed by a dynamic compensation sealing assembly. The dynamic compensation sealing assembly is a magnetic fluid-titanium alloy bellows composite sealing structure. The magnetic fluid is a mixture of Fe3O4 nanoparticles and perfluoropolyether oil at a ratio of 20wt%, and the particle size of the Fe3O4 nanoparticles is 10nm. The leakage rate of the magnetic fluid-titanium alloy bellows composite sealing structure is ≤1×10 -9 Pa·m³ / s.

5. A prefabricated pluggable connection system for high-voltage submarine cables according to claim 4, characterized in that, The high-voltage submarine cable (1) is embedded with a distributed fiber Bragg grating sensor. A fiber Bragg grating sensor is arranged every 0.5m along the axial direction of the high-voltage submarine cable (1). The spatial resolution of the distributed fiber Bragg grating sensor is 0.1m. It is used to monitor the temperature, strain and partial discharge of the high-voltage submarine cable (1).

6. A prefabricated pluggable connection system for high-voltage submarine cables according to claim 1, characterized in that, The high-voltage submarine cable module is prefabricated using the following method: Step S001: Install the composite stress cone (9) in the workshop. The composite stress cone (9) is pre-filled with SF6 / N2 mixed gas with a pressure of 0.4MPa. Step S002: Conduct high voltage withstand test, lightning impulse test, and partial discharge test on the prefabricated module; Step S003: Using a laser-vision positioning system mounted on a deck rail robot, the submarine cable terminal plug (3) is aligned with the submarine cable terminal socket (4) with a positioning accuracy of ±0.1mm; the deck rail robot integrates laser-ultrasonic positioning and hydraulic insertion mechanism with a positioning accuracy of ±0.05mm and an insertion time of ≤2 hours; Step S004: Hydraulic drive insertion, bellows compensation ±15mm axial displacement, magnetic fluid seal lateral vibration, amplitude ±3mm, frequency ≤20Hz; Step S005: After power-on, the data is monitored in real time by distributed fiber optic sensors and uploaded to the land-based monitoring platform.

7. A prefabricated pluggable connection system for high-voltage submarine cables according to claim 1, characterized in that, The insertion and removal interfaces of the submarine cable terminal plug (3) and the submarine cable terminal socket (4) are provided with three layers of nonlinear conductive silicone rubber, with an inner layer carbon black concentration of 15wt%, a middle layer of 10wt%, and an outer layer of 5wt%, and a field strength dependence coefficient β=0.05.

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