A deep-sea ROV high-voltage direct-current power supply system

Abstract

The application discloses a kind of deep-sea ROV high-voltage direct-current power supply systems, including water surface main power circuit, water surface auxiliary power supply circuit is placed in the underwater voltage reduction variable unit of dry pressure cabin body, still including the double CAN bus communication subsystem of two-way data transmission by water surface CAN bus and water surface main control gateway and underwater CAN bus and underwater main control gateway, for system multistage fault protection and execute power-on, power-off, emergency shutdown, fault shutdown and reset procedure, the fault level includes event record level, alarm level, sequential shutdown level and emergency shutdown level;The application cable loss is low, control electricity is reliable, cooling maintenance-free, can be adapted to different cable length, suitable for 6000 meters level deep-sea ROV power supply.

Description

Technical Field

[0001] This invention belongs to the field of power supply and control technology for deep-sea operation equipment, specifically relating to a high-voltage DC power supply system suitable for 6000-meter-class deep-sea remotely operated vehicles (ROVs). Background Technology

[0002] The power supply system of deep-sea ROVs needs to transmit power from the surface mother ship to the underwater environment via a kilometre cable several kilometers long. This faces constraints such as long-distance transmission losses, high static pressure in the deep sea, and the difficulty of online maintenance of underwater equipment. Although AC transmission schemes can step up the voltage on the surface and step down the voltage underwater for rectification, the distributed capacitance of long lines is significant, the charging current increases with the cable length, the transmission efficiency decreases, and the alternating electromagnetic field can also interfere with communication signals transmitted on the same cable.

[0003] Oil-immersed pressure compensation schemes involve immersing power devices in insulating oil and balancing the internal and external pressure differences using pressure compensators. However, the devices are subjected to high static pressure for extended periods, the oil has poor compatibility with materials, and maintenance requires draining and replenishing oil, making the process cumbersome. Existing research on ROV high-voltage DC power distribution focuses primarily on power conversion topologies and inter-module communication, lacking system-level solutions for 12-pulse rectification, umbilical cable voltage drop adaptation, dual-circuit auxiliary power supply, system-level power-on / off state machines, multi-level fault hierarchical response, and dry compartment fluoride cooling.

[0004] Furthermore, different water depths and operating radii correspond to umbilical cables of different lengths, resulting in significant differences in DC voltage drop across the cables. Underwater converters with fixed input ranges are difficult to use universally, limiting the system's reusability in different sea areas. Summary of the Invention

[0005] To overcome the above shortcomings, the purpose of this invention is to provide a deep-sea ROV high-voltage DC power supply system with low transmission loss, strong cable length adaptability, reliable control, maintenance-free underwater cooling, and closed-loop control and protection.

[0006] To achieve the above objectives, the technical solution adopted by this invention to solve its technical problem is: a high-voltage DC power supply system for deep-sea ROVs, comprising a surface main power circuit, a surface auxiliary power supply circuit electrically isolated from the surface main power circuit, and an underwater depressurization conversion unit placed inside a dry pressure tank. The surface main power circuit includes a three-winding rectifier transformer whose primary side is connected to 690V ship power. The two sets of secondary windings of the three-winding rectifier transformer output AC power with a 30° phase difference using delta and star connections respectively, which are then fed to… Two sets of three-phase 12-pulse full-bridge rectifiers are input, and the outputs are superimposed in series to generate 5000V DC power. The surface auxiliary power supply circuit includes a 10kVA auxiliary transformer connected to the 690V ship power supply on the primary side. The auxiliary transformer steps up the ship power to 3300V and transmits it to the underwater dry pressure tank via an auxiliary umbilical cable. The dry pressure tank is filled with fluorinated liquid as a cooling medium. The underwater step-down conversion unit steps down the high-voltage DC input from the surface main power circuit and the surface auxiliary power supply circuit to a low voltage usable by the electrical equipment via the main umbilical cable. The DC power supply to the DC bus includes parallel multi-channel step-down DC / DC power conversion modules forming an N+1 redundant low-voltage DC control circuit. Each DC / DC power conversion module has a fuse connected to its front end. Within a wide input range, it directly converts the high-voltage DC input from the umbilical cable into 600V regulated DC, with the output connected in parallel to the 600V DC bus to cover the voltage drop on the cable caused by variations in umbilical cable length and load. In the event of a failure in any DC / DC power conversion module, the fuse at its front end automatically isolates the fault, and the controller automatically activates the backup DC / DC power conversion module to maintain power supply. The system also includes a dual CAN bus communication subsystem that uses a surface CAN bus and a surface main control gateway, as well as an underwater CAN bus and an underwater main control gateway master node, as gateways to achieve bidirectional data transmission between the surface and underwater environments. This dual CAN bus communication subsystem transmits multi-level status control signals for multi-level system fault protection and execution of power-on, power-off, emergency shutdown, fault shutdown, and reset procedures. The fault levels include event logging, alarm, sequential shutdown, and emergency shutdown.

[0007] The aforementioned deep-sea ROV high-voltage DC power supply system has a surface auxiliary power supply circuit that converts low-voltage AC to low-voltage AC via an auxiliary step-down transformer and outputs a first low-voltage DC control power supply through rectification. This first low-voltage DC control power supply is then connected in parallel with the second low-voltage DC control power supply obtained by stepping down the DC bus on the surface main power circuit via the underwater step-down link and fed into the control bus to form a redundant power supply.

[0008] The aforementioned deep-sea ROV high-voltage DC power supply system physically separates the surface CAN bus and the underwater CAN bus. The surface CAN bus sends transparent control frames to the underwater CAN bus through a gateway node, and the underwater CAN bus sends transparent status frames to the surface CAN bus through a gateway node.

[0009] Furthermore, the surface CAN bus and underwater CAN bus send heartbeat frames at fixed intervals through the gateway node, and set a timeout retry mechanism for the transparent control frame. If the frame is not received within the set time, the node is determined to be offline, and a communication fault alarm is set if the retry fails.

[0010] The aforementioned deep-sea ROV high-voltage DC power supply system includes a humidity sensor and a pressure sensor inside its dry pressure-resistant hull to monitor the hull's sealing status. When the humidity inside the hull rises abnormally, it triggers a multi-level fault protection system with an early warning level and notifies the surface. When the pressure inside the hull rises abnormally, it triggers an emergency shutdown protection system. Before the seawater comes into contact with the energized components, it cuts off the main power supply of the surface main power circuit. After triggering the emergency shutdown, the surface auxiliary power supply circuit maintains low-voltage DC control power supply and continuously reports the hull status.

[0011] Furthermore, the power-on process is performed in the following order: powering on the auxiliary power supply circuit on the water surface, powering on the main power circuit on the water surface, pre-charging, and starting the DC / DC power conversion module; the power-off process is the reverse of the power-on process.

[0012] Furthermore, the emergency shutdown procedure involves immediately entering the emergency shutdown state when an emergency shutdown-level fault or external emergency stop signal is detected under any condition, simultaneously disconnecting all contactors and sending an emergency shutdown message, requiring manual reset before power can be restored; the fault shutdown procedure involves switching to the fault shutdown state when a sequential shutdown-level fault is detected and shutting down according to the power-off procedure sequence.

[0013] Furthermore, the reset process involves clearing the fault latch after the fault source is restored and a reset command is received, and then returning to the initial power-off state via the emergency shutdown process or the fault shutdown process.

[0014] Furthermore, the pre-charging process is executed in two coordinated stages: on the surface side and underwater side. On the surface side, the distributed capacitance of the umbilical cable and the DC bus capacitor are charged through the current-limiting resistor. After the bus voltage reaches a predetermined proportion of the rated value and the charging current decays to a steady state, the pre-charging is determined to be complete and the main contactor is closed. On the underwater side, after the input voltage rises to a safe threshold, the input capacitor of the underwater step-down converter is pre-charged a second time. Before entering the pre-charging stage, a mandatory check is performed to ensure that all multi-dimensional interlocking conditions, such as insulation, cabinet door interlocking, transformer and cooling temperature, online status of key communication nodes, cabin sealing status, and current fault level, are met.

[0015] The beneficial effects of this invention are as follows: This invention reduces cable loss and harmonic pollution by using 12-pulse rectification and 5000V high-voltage DC transmission; it covers voltage drops of different cable lengths with wide input voltage reduction and achieves platform-based reuse; the low-voltage DC control power supply is dual-source redundant, controllable in the initial power-on stage, and can report faults; the dry tank fluorinated liquid cooling decouples pressure bearing and heat dissipation, and is maintenance-free underwater; the multi-level state machine, combined with multi-dimensional interlocks and multi-level fault protection, forms a closed-loop control and protection system; and the dual CAN bus, through gateway transmission, ensures reliable and controllable information links between the surface and underwater. Attached Figure Description

[0016] Figure 1 This is a diagram showing the overall architecture of the high-voltage DC power supply system of the present invention;

[0017] Figure 2 This is a topology diagram of the 12-pulse rectifier of the present invention;

[0018] Figure 3 This is a structural diagram of the underwater pressure reduction conversion unit of the present invention;

[0019] Figure 4 This is the fault level mapping matrix table of the present invention;

[0020] Figure 5 This is a flowchart of the fault classification response of the present invention.

[0021] The attached figures are labeled as follows: 1—Surface main power circuit, 2—Surface auxiliary power supply circuit, 3—Underwater step-down converter unit, 41—Surface CAN bus, 42—Underwater CAN bus. Detailed Implementation

[0022] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Reference Figure 1 As shown, the present invention discloses a deep-sea ROV high-voltage DC power supply system, including a surface main power circuit 1, a surface auxiliary power supply circuit 2, an underwater voltage conversion unit 3, and a dual CAN bus communication subsystem.

[0024] The surface main power circuit 1 steps up and rectifies the ship's electricity into high-voltage DC, and transmits the power to the underwater via the main power core of the umbilical cable. The surface auxiliary power supply circuit 2 independently converts the ship's electricity into high-voltage AC, transmits it to the underwater via the auxiliary umbilical cable, and converts it into low-voltage DC control power. The surface auxiliary power supply circuit 2 is put into operation before the surface main power circuit 1 is powered on, and maintains power supply after the surface main power circuit 1 trips due to a fault.

[0025] Reference Figure 2As shown, the main power circuit 1 on the surface uses a three-winding rectifier transformer in conjunction with a 12-pulse rectifier to step up and rectify the ship's electrical power to 5000V high-voltage DC, which is then transmitted underwater via the main power core of the umbilical cable. The two secondary sides of the transformer are connected in delta and star configurations respectively, naturally forming a 30° phase difference. The outputs of the two bridges are superimposed in series to directly achieve the target voltage. High-voltage DC transmission reduces current and losses on the cable, and the 12-pulse structure suppresses the 5th and 7th characteristic harmonics, reducing harmonic pollution to the mother ship's power grid.

[0026] In this embodiment, the main power circuit 1 on the water surface uses a 250kVA three-winding rectifier transformer. The primary side is connected to the mother ship's 690V / 50Hz AC power, and the secondary side has two sets of windings: a delta-connected 1850V and a star-connected 1850V, with a phase difference of 30°. The two sets of AC power are fed into two sets of three-phase full-bridge rectifiers, with each set outputting approximately 2500V DC. The two sets are connected in series to obtain approximately 5000V DC, which is then sent to the underwater via the main power core of the umbilical cable. The secondary side double-bridge series connection directly reaches 5000V, eliminating the need for a first-stage DC / DC boost stage. The 12-pulse rectifier generates 12 pulses of DC voltage waveform per power frequency cycle, suppressing the 5th and 7th characteristic harmonics, and the total harmonic distortion rate of the input current is lower than that of the 6-pulse scheme.

[0027] This invention uses a three-winding rectifier transformer in conjunction with a 12-pulse rectifier to convert 690V marine power to 5000V high-voltage DC, which is then transmitted to the underwater via the main power core of the umbilical cable. The system is redundantly supplied by an independent auxiliary circuit and a main power derivative circuit connected in parallel. The underwater dry compartment is cooled by fluorinated liquid immersion. The system forms a closed loop with state machine power-on / off control, pre-charge multi-dimensional interlocking, multi-level fault classification protection, and dual CAN gateway pass-through.

[0028] The low-voltage DC control circuit of this invention also includes a path derived from the main power circuit 1 on the water surface, which is obtained by step-down conversion via the DC bus on the main power circuit's underwater step-down link. The second path directly steps down to 24V / 48V via the underwater step-down link (600V DC bus) of the main power circuit 1 on the water surface. The two low-voltage DC control circuits are connected in parallel to the control bus to form redundancy. During periods when the main power circuit 1 on the water surface is not in operation or has tripped due to a fault, the independent auxiliary power supply circuit 2 on the water surface continues to supply power to the control circuit and the CAN communication node; during the operation of the main power circuit 1, both circuits provide power simultaneously, ensuring uninterrupted status monitoring and fault diagnosis.

[0029] Dual-circuit auxiliary power supply, electrically isolated from the main power: Low-voltage DC control power is supplied using dual-source parallel redundancy: The independent auxiliary circuit transmits and converts low-voltage DC control power independently via an auxiliary umbilical cable, is electrically isolated from the main power circuit, and is put into operation before the main power; the main power underwater step-down link can also derive to supply low-voltage DC control power, and the two circuits are connected in parallel to the low-voltage control bus. During the period when the main power is not in operation or during a fault trip, the independent auxiliary circuit maintains underwater control and communication power supply.

[0030] In this embodiment, the surface auxiliary power supply circuit 2 adopts a dual-source parallel redundancy method based on two low-voltage DC control circuits. The first independent auxiliary circuit uses a 10kVA auxiliary transformer to step up the 690V ship power to 3300V AC, which is then directly transmitted underwater via the auxiliary umbilical cable. The underwater auxiliary step-down transformer converts this to low-voltage AC and rectifies it to output 24V / 48V low-voltage DC control power, which is used by the CAN bus, main control gateway, sensors, and contactor coils. The surface auxiliary power supply circuit 2 is electrically isolated from the surface main power circuit 1 and is activated before the main power circuit. The main propulsion load drives the propulsion motor via a DC / AC inverter. The 24V / 48V low-voltage DC control power is obtained by direct step-down conversion from the 600V DC bus, which directly supplies power to the load.

[0031] Reference Figure 3 As shown, the underwater pressure conversion unit 3 is placed inside a dry pressure-resistant tank. The tank is designed to withstand pressure at the target operating water depth, capable of withstanding deep-sea static pressure up to 6000 meters. The tank is filled with fluorinated liquid at a preset ratio to immerse the power devices. An air volume is reserved above the liquid surface to accommodate the thermal expansion of the fluorinated liquid and suppress pressure rise within the tank. Heat dissipation fins are installed on the inner wall of the tank to assist in heat dissipation. The fluorinated liquid is non-conductive, non-flammable, and chemically inert, serving both heat dissipation and auxiliary insulation functions. Dry tank fluorinated liquid immersion cooling and sealing monitoring: a thick-walled pressure-resistant shell withstands the deep-sea static pressure, while fluorinated liquid-immersed power devices provide heat dissipation and auxiliary insulation, decoupling pressure bearing and heat dissipation; humidity and pressure sensors monitor the sealing status, and leakage is triggered by humidity and pressure-level protection, cutting off main power before seawater contacts energized components.

[0032] The dry pressure chamber is equipped with humidity and pressure sensors to monitor the chamber's sealing status. When the humidity inside the chamber rises abnormally, a warning-level fault is triggered and the surface is notified. When the pressure inside the chamber rises abnormally, an emergency shutdown protection is triggered. The main power supply of the surface main power circuit 1 is cut off before the seawater comes into contact with the energized parts. After the emergency shutdown is triggered, the surface auxiliary power supply circuit 2 maintains low-voltage DC control power supply and continuously reports the chamber status.

[0033] The underwater step-down conversion unit 3 includes multiple parallel high-voltage DC / DC power conversion modules forming N+1 redundancy: each module directly converts the high-voltage DC input from the umbilical cable into 600V DC with a wide input range, and the output is connected in parallel to the 600V DC bus to cover the voltage drop on the cable caused by changes in the length of the umbilical cable and the load; when any working module fails, it is automatically isolated by the fuse at the front end of the faulty module, and the controller automatically activates the backup module to maintain power supply; the 600V DC bus directly supplies power to the load, the main propulsion load drives the propulsion motor through the DC / AC inverter, and the low-voltage DC control power is obtained by direct step-down conversion from the 600V DC bus.

[0034] The N+1 parallel redundant DC / DC power conversion module directly regulates the high voltage DC input from the umbilical cable to 600V, and the output is connected in parallel to the 600V DC bus. If any module fails, it is isolated by the front-end fuse and automatically activated as a backup, without secondary voltage reduction at the power stage.

[0035] Each DC / DC power conversion module is designed with a wide input range to adapt to umbilical cable voltage drops: the longer the cable and the heavier the load, the lower the underwater input voltage. The module group maintains a regulated 600V output voltage within the range from the rated output voltage to the voltage drop on the cable after deducting the maximum design cable length and rated load voltage drop, adapting to different cable lengths and operating water depths without hardware modifications. The wide input range of the underwater DC / DC power conversion modules covers the voltage range corresponding to the rated output voltage minus the voltage drop on the cable under the maximum design cable length and rated load conditions, enabling the same power supply system to maintain a stable 600V DC output without hardware configuration changes under different umbilical cable lengths and operating water depths.

[0036] This invention utilizes an N+1 parallel redundant DC / DC power conversion module for underwater voltage reduction. Each module receives high-voltage DC power from the umbilical cable with a wide input range and directly regulates it to 600V, with the output connected in parallel to the 600V DC bus. The bus directly supplies power to the load. The main propulsion load is driven by a DC / AC inverter, and tools are connected to the bus. Low-voltage DC control power is obtained directly from the 600V bus without secondary voltage reduction at the power stage. Any module failure is automatically isolated and a backup is activated. The wide input design covers voltage drop fluctuations caused by cable length and load, allowing the same system to adapt to different operating water depths.

[0037] The dual CAN bus communication subsystem consists of a surface CAN bus 41 and a surface main control gateway, and an underwater CAN bus 42 and an underwater main control gateway. The surface CAN bus 41 and the underwater CAN bus 42 are physically separated. The surface CAN bus 41 sends transparent control frames to the underwater CAN bus 42 through the gateway node, and the underwater CAN bus 42 sends transparent status frames to the surface CAN bus 41 through the gateway node. The underwater node status frame is forwarded to the surface control terminal as a transparent status frame, and the control frame of the surface control terminal to the underwater equipment is forwarded to the underwater target node. The surface CAN bus 41 and the underwater CAN bus 42 send heartbeat frames at fixed intervals through the gateway node. A timeout retry mechanism is set for the transparent control frame. If the frame is not received within the set time, the node is determined to be offline. If the retry fails, a communication fault alarm is set. Fault protection is organized in a hierarchical manner according to events, alarms, sequential shutdown, and emergency shutdown. The fault source is automatically mapped to the corresponding level according to the degree of physical quantity and responds differently. Faults at the sequential shutdown level and above are automatically latched. Power can only be restored after the fault source is recovered and manually reset.

[0038] The dual CAN bus communication subsystem transmits multi-level status control signals for multi-level system fault protection and to execute power-on, power-off, emergency stop, fault stop, and reset procedures.

[0039] The fault levels include event logging, alarm, sequential shutdown, and emergency shutdown. Faults are automatically mapped to the corresponding level based on their source and trigger differentiated responses. Event logging only records logs; alarms output prompts with unlimited power, and alarms also provide HMI and communication status prompts with unlimited power; sequential shutdown triggers sequential shutdown according to the power outage sequence; emergency shutdown immediately and synchronously disconnects all contactors. Each fault source is automatically mapped to the corresponding level based on the severity of the physical quantity. The same fault source can be mapped to different levels at different severity ranges; faults at the sequential shutdown level and above are automatically latched, requiring the fault source to be restored and a manual reset command to be received before power can be restored.

[0040] Figure 4 The fault level mapping matrix table of this invention is divided into 14 types of fault sources, ranging from level 0 to level 3. The faulty module is isolated by the front-end fuse, and the PLC automatically activates the backup (≤200ms). Figure 5 This is a flowchart of the fault classification response of the present invention.

[0041] The power-on process is performed in the following order: powering on and confirming the auxiliary power supply circuit 2 on the water surface, powering on and confirming the main power circuit 1 on the water surface, pre-charging, closing the main contactor, and starting and confirming the DC / DC power conversion module. Each step is conditional on the arrival of the feedback signal and is equipped with independent timeout protection.

[0042] The power-off procedure is the reverse of the power-on procedure, i.e., it is executed in reverse order. After the bus discharges to a safe voltage, the next step continues: when a shutdown command is received under normal operating conditions, the DC / DC shutdown, main contactor disconnection, bus discharge, control power disconnection, and auxiliary power disconnection are executed in reverse order until the system is powered off.

[0043] The emergency shutdown procedure is initiated when an emergency-level fault or external emergency stop occurs under any condition, simultaneously disconnecting all contactors. Power can only be restored after manual reset.

[0044] The aforementioned fault shutdown procedure involves detecting a sequential shutdown-level fault, transitioning to a fault shutdown state, and shutting down the system in an orderly manner according to the power-off sequence. In the emergency stage, all contactors are immediately and synchronously disconnected; the hardware emergency stop circuit directly cuts off the contactor coils; and the software synchronously enters the emergency stop logic.

[0045] The pre-charging process is executed in two coordinated stages: one on the surface side and one underwater side. On the surface side, the distributed capacitance of the umbilical cable and the DC bus capacitance are charged through a current-limiting resistor. When the bus voltage reaches a predetermined proportion of the rated value, the charging current decays to a steady state, and no timeout occurs, the pre-charging is considered complete, and the main contactor is closed. On the underwater side, after the input voltage rises to a safe threshold, the input capacitor of the underwater DC / DC converter module is pre-charged a second time to suppress closing impact. Before pre-charging, a mandatory check is performed to ensure that all interlocking conditions, such as insulation, cabinet door interlocking, transformer and cooling temperature, online communication nodes, cabin sealing, and current fault level, are met. The pre-charging is coordinated on both the surface and underwater sides to suppress closing impact, and each threshold is set according to the system configuration.

[0046] This invention system collects fault data such as transformer temperature, bus voltage and current, insulation, primary current, fan and pump status, cabinet door interlocks, key node online status, DC / DC module status, pre-charge status, and cabin humidity and pressure. It automatically maps fault levels according to the severity of the physical quantities. Faults at the sequential shutdown level and above are automatically latched, requiring fault source recovery and manual reset before power can be restored. Cabin sealing is monitored using combined humidity and pressure monitoring. Humidity exceeding a threshold and persisting triggers a warning level; abnormal pressure increases trigger an emergency shutdown. Main power is cut off before seawater contacts live components, while an independent auxiliary circuit maintains power and continuously reports cabin status.

[0047] The surface control unit is centered around a PLC, connected to the surface and underwater CAN bus 42 via fieldbus, and communicates with the HMI via Ethernet using the MODBUSTCP protocol. The PLC schedules communication transmission and reception, register refresh, fault management, and state machine stepping according to a fixed cycle. The HMI provides system overview, converter unit monitoring, hull monitoring, and alarm control screens. The system transmits 5000V high-voltage DC via umbilical cable, keeping the cable current and losses at a low level. Combined with the underwater wide-input converter, it can cover the full-load voltage drop of long cables. If low-voltage DC or AC is used for direct transmission, the cable current and losses will increase by more than an order of magnitude at the same power, making long-distance deep-sea power supply solutions impractical.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some of the application examples. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A high-voltage DC power supply system for deep-sea ROVs, characterized in that: The system includes a surface main power circuit (1), a surface auxiliary power supply circuit (2) electrically isolated from the surface main power circuit (1), and a water-based depressurization conversion unit (3) housed in a dry pressure tank. The surface main power circuit (1) includes a three-winding rectifier transformer connected to the ship's electrical system on its primary side. The two sets of secondary sides of the three-winding rectifier transformer are connected in a delta and star configuration, respectively, to output AC power with a phase difference of 30°. These AC power is fed into two sets of three-phase 12-pulse full-bridge rectifiers, and the outputs are superimposed in series to generate DC power. The surface auxiliary power supply circuit (2) includes an auxiliary transformer connected to the ship's electrical system on its primary side. The auxiliary transformer boosts the ship's electrical power and transmits it to the dry pressure tank via an auxiliary umbilical cable. The dry pressure tank is filled with fluorinated liquid. The water-based depressurization conversion unit (3) 3) The high voltage DC input from the main power circuit (1) and the auxiliary power supply circuit (2) on the surface is reduced to low voltage DC and sent to the DC bus through the main umbilical cable. This includes redundant parallel multi-channel DC / DC power conversion modules. The front end of the DC / DC power conversion modules is connected to fuses. It also includes a dual CAN bus communication subsystem that realizes bidirectional data transmission through the surface CAN bus (41) and the surface main control gateway and the underwater CAN bus (42) and the underwater main control gateway. The dual CAN bus communication subsystem transmits multi-level status control signals for multi-level fault protection of the system and execution of power-on, power-off, emergency shutdown, fault shutdown and reset procedures. The fault levels include event recording level, alarm level, sequential shutdown level and emergency shutdown level.

2. The deep-sea ROV high-voltage DC power supply system according to claim 1, characterized in that, The auxiliary power supply circuit (2) on the water surface is converted into low-voltage AC by an auxiliary step-down transformer and then rectified to output the first low-voltage DC control power. This first low-voltage DC control power is connected in parallel with the second low-voltage DC control power obtained by the step-down transformation of the main power circuit (1) on the water surface via the DC bus on the step-down link and then fed into the control bus to form a redundant power supply.

3. The deep-sea ROV high-voltage DC power supply system according to claim 1, characterized in that, The surface CAN bus (41) and the underwater CAN bus (42) are physically separated. The surface CAN bus (41) sends a transparent control frame to the underwater CAN bus (42) through the gateway node, and the underwater CAN bus (42) sends a transparent status frame to the surface CAN bus (41) through the gateway node.

4. The deep-sea ROV high-voltage DC power supply system according to claim 3, characterized in that, The surface CAN bus (41) and underwater CAN bus (42) send heartbeat frames at fixed intervals through the gateway node. If a heartbeat frame is not received within a set time, the node is determined to be offline and a communication failure alarm is triggered upon retrying.

5. A high-voltage DC power supply system for deep-sea ROVs according to claim 1, 2, 3, or 4, characterized in that, The dry pressure chamber is equipped with a humidity sensor and a pressure sensor. When the humidity inside the chamber rises abnormally, it triggers a multi-level fault protection warning level. When the pressure inside the chamber rises abnormally, it triggers an emergency shutdown. Before the seawater comes into contact with the live parts, the power supply of the main power circuit (1) on the water surface is cut off, and the auxiliary power supply circuit (2) on the water surface maintains the low-voltage DC control power supply and reports the status of the chamber.

6. A high-voltage DC power supply system for deep-sea ROVs according to claim 5, characterized in that, The power-on process is performed in the following order: powering on the auxiliary power supply circuit (2) on the water surface, powering on the main power circuit (1) on the water surface, pre-charging, and starting the DC / DC power conversion module; the power-off process is the opposite of the power-on process.

7. A deep-sea ROV high-voltage DC power supply system according to claim 5, characterized in that, The emergency shutdown procedure involves simultaneously disconnecting all contactors and sending an emergency shutdown message when an emergency shutdown-level fault or an external emergency stop signal is detected. Power can only be restored after manual reset. The fault shutdown procedure involves shutting down the machine in the order of the power-off procedure when a sequential shutdown-level fault is detected.

8. A high-voltage DC power supply system for deep-sea ROVs according to claim 5, characterized in that, The reset process involves clearing the fault latch after the fault source is restored and a reset command is received, and then returning to the initial power-off state via the emergency stop process or the fault stop process.

9. A high-voltage DC power supply system for deep-sea ROVs according to claim 5, characterized in that, The pre-charging process is carried out in two coordinated stages: the surface side and the underwater side. On the surface side, the distributed capacitance of the umbilical cable and the capacitance of the DC bus are charged. When the bus voltage reaches a predetermined ratio of the rated value and the charging current decays to a steady state, the pre-charging is determined to be completed. On the underwater side, after the input voltage rises to a safe threshold, the input capacitor of the underwater step-down converter unit (3) is pre-charged a second time.

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