Self-checking and fault isolation device for underwater power supply bus and method thereof

Abstract

This invention discloses a self-testing and fault isolation device and method for an underwater power supply bus. The device includes a communication optical fiber and self-testing units spaced along the bus, comprising an electronic switch module, a current detection module, an auxiliary power supply module, and a control module. The control module controls the switching of the electronic switch module and identifies current anomalies. The electronic switch module is located on the bus. The current detection module is located downstream of the electronic switch module. The auxiliary power supply module provides power to the self-testing units during self-testing. The method is as follows: Before formal power-on, a low-power detection voltage is injected, and a reverse current is used to sequentially close the self-testing units from the downstream end of the bus to the upstream end. Each section of the self-testing unit collects current sequentially and determines whether there is a fault. If a fault is found, the electronic switch module of that section is quickly disconnected. After a normal self-test, the bus is powered forward, and the self-testing units automatically exit the main circuit without affecting normal transmission. This invention completes section-level self-testing and fault location of the bus before power-on, reducing the risk of powering on with faults.

Description

Technical Field

[0001] This invention relates to the field of underwater power supply technology, specifically to a self-testing and fault isolation device and method for an underwater power supply bus. Background Technology

[0002] With the continuous development of marine engineering, underwater exploration, underwater operation equipment, underwater long-term observation systems, and deep-sea resource development, underwater power supply systems, as an important infrastructure to ensure the long-term and stable operation of various underwater equipment, have been widely used in underwater observation networks, underwater operation platforms, marine engineering equipment, and other underwater centralized power supply scenarios.

[0003] In typical underwater power supply systems, to meet the centralized power supply needs of multiple underwater nodes or functional modules and reduce the costs of submarine cable laying and system deployment, a main power supply bus is typically used as the backbone channel for underwater power transmission. Underwater connection nodes or power conversion units then convert the bus power into the operating voltage and power supply form required by each functional module, thereby achieving unified power supply and distribution management for different underwater loads. The power supply bus is generally constructed using high-voltage direct current (HVDC) to achieve centralized transmission of long-distance, high-power electricity and serves as the core power supply link of the entire underwater power supply network.

[0004] Due to the characteristics of the underwater environment, such as high humidity, high pressure, high salinity, strong corrosiveness, and difficult maintenance, underwater power supply lines operate under complex and harsh conditions for extended periods. During long-term service, the lines may experience abnormalities such as decreased insulation performance, aging connection points, partial short circuits, poor contact, and increased leakage current. If a short circuit fault occurs on the main busbar, it can cause a sudden voltage collapse in the entire power supply network, leading to a complete power outage or even system paralysis. Technologies for isolating and protecting against busbar faults have been applied, such as the NEPTUNE monitoring network in Canada, which can reliably locate and isolate faults when they occur on the busbar.

[0005] However, the methods described above are designed for busbar faults during the operation of the power supply system. If a fault exists on the busbar before power-on, performing a power-on operation at this time will inject high-voltage energy instantaneously into the fault point, potentially causing continuous arcing and localized high-temperature ablation. This could not only damage the busbar itself but also burn out underwater junction boxes, connectors, and downstream critical equipment. In severe cases, it could even cause permanent failure of the underwater node, resulting in extremely high maintenance and replacement costs. Therefore, it is essential to inspect the electrical condition of the power supply busbar before putting the underwater power supply system into operation to confirm whether the busbar meets the conditions for safe power-on, thereby reducing the operational risks of the system.

[0006] Secondly, a busbar power outage often means the entire subsea operation system is forced to shut down. System shutdowns caused by busbar failures not only result in the loss of long-term observation data and interruptions to scientific missions, but can also lead to missed sea trial windows, halted engineering operations, and even equipment scrapping, resulting in significant economic losses. Therefore, the busbar self-inspection device must not only be able to promptly isolate the faulty section to prevent its spread, but also achieve rapid location and confirmation of the faulty section, thus providing accurate data for subsequent repairs and restoration.

[0007] Furthermore, since underwater power supply networks are typically long-term, permanent installations, maintenance and replacement costs are extremely high, and the requirements for system reliability are extremely stringent. Connecting the self-test unit to the bus inevitably introduces additional electrical branches, connection nodes, and electronic components, increasing system complexity and potential failure points. If the self-test unit fails during normal bus power supply, it may adversely affect the bus's electrical characteristics, such as introducing additional loads, causing voltage fluctuations, creating abnormal current paths, or even becoming a fault propagation channel, causing localized faults to evolve into bus-level faults, further increasing the difficulty of fault isolation and location. Therefore, how to achieve safe self-testing of the bus while minimizing the impact of the self-testing device on the normal operation of the bus is a key technical problem that urgently needs to be solved in this field.

[0008] In summary, existing technologies still have shortcomings in the pre-power-on self-inspection management of underwater power supply system busbars. There is a lack of a device and method that can ensure the safe self-inspection of the busbar while preventing the self-inspection unit from introducing potential safety hazards during the normal operation of the busbar. Summary of the Invention

[0009] This invention aims to overcome the shortcomings of existing underwater power supply systems in terms of insufficient busbar status detection and fault location isolation capabilities, and provides a device and method for rapid self-checking of the busbar line status before normal operation. This self-checking device is deployed in the form of self-checking units along the busbar power supply link. Before the busbar is officially put into operation, a detection loop is established using a reverse pre-power-on method, thereby performing segment-by-segment closed-loop verification of the busbar line. The pre-power-on voltage is preferably medium to low voltage to avoid excessive impact from busbar faults. When an abnormal section is detected, an electronic switch performs a disconnect operation to isolate the fault and feeds back the fault signal via communication fiber optic cable. Once the busbar enters the formal power-on operating state, the self-checking unit automatically exits and is not connected to the main busbar circuit, thus having no additional impact on the normal power supply process of the busbar. Controllable shutdown of relevant switches is achieved via communication fiber optic cable.

[0010] To achieve the above objectives, the present invention provides the following technical solution: A self-testing and fault isolation device for an underwater power supply busbar is disclosed. The busbar is powered by a shore-based power supply terminal and is used to supply power to a load. A load branch power conversion unit is set between the busbar and the load. The self-testing and fault isolation device includes several self-testing units and a communication optical fiber. Based on the current flow direction when the busbar is working normally, the upstream of the busbar is defined as close to the shore-based power supply terminal, and the downstream of the busbar is defined as far away from the shore-based power supply terminal. Several self-testing units are arranged at intervals along the busbar and establish a communication connection with the shore-based power supply terminal through the communication optical fiber. The several self-testing units divide the busbar into multiple detection sections to realize segment-by-segment reverse pre-power-on self-testing and fault isolation at the busbar segment level. The self-test unit includes an electronic switch module, a current detection module, an auxiliary power supply module, and a control module; The control module is used to control the switching of the electronic switch module and identify current anomalies, and to feed back the electronic switch status to the shore power supply terminal and remote controllable shutdown via communication optical fiber. The electronic switch module is deployed on the busbar and is used to conduct the busbar link segment by segment according to the closing strategy of the control module during the reverse pre-power-on phase, and to perform a fast disconnection operation when an abnormal section is detected, thereby realizing the isolation and removal of the faulty branch. The current detection module is located downstream of the electronic switch module and is used to collect current change information during the closure process of the busbar in the section in real time, providing data for the current anomaly identification of the control module. The auxiliary power supply module is used to provide stable operating power to each module of the self-test unit during reverse pre-power-on self-test, and stops supplying power when the bus is working normally.

[0011] Furthermore, the electronic switch module is specifically a self-locking electronic switch to ensure that the electronic switch remains closed when the bus switches from the reverse pre-power-on self-test state to the normal operating state.

[0012] Furthermore, the current detection module includes a working conduction branch and a detection conduction branch connected in parallel on the busbar; The working conduction branch is a working conduction branch diode. The anode of the working conduction branch diode faces upstream of the bus and the cathode faces downstream of the bus, providing a current path for the normal working state of the bus. When the bus is in the reverse pre-energization state, the current can enter the detection conduction branch. The detection conduction branch consists of a detection conduction branch diode and a sampling resistor connected in series. The anode of the detection conduction branch diode faces downstream of the bus and the cathode faces upstream of the bus, providing a current path for the reverse pre-power-on self-test process, thereby preventing current from flowing through the detection branch during normal operation.

[0013] The sampling resistor is used for current information acquisition and limiting the current during the reverse pre-power-on self-test phase to ensure that no excessive inrush current is generated in the event of a potential short-circuit anomaly.

[0014] Furthermore, the auxiliary power module includes a pre-power-on energy harvesting branch and a DC-DC power supply unit; The pre-power-on energy extraction branch is a Zener diode connected in series on the bus. The anode of the Zener diode faces upstream of the bus, and the cathode faces downstream of the bus. The Zener diode is used to generate a voltage drop during the reverse breakdown phase of the reverse pre-power-on stage to supply power to the subsequent stage. When the bus is working normally, it is forward-conducting and the voltage drop is negligible, so that the self-test unit has no power input and cannot work. It is then disconnected from the bus to avoid the self-test unit affecting the reliability of the bus.

[0015] The DC-DC power supply unit converts the voltage drop generated by the reverse breakdown of the Zener diode during the reverse pre-power-on self-test phase into a stable operating voltage required by each module of the self-test unit. This enables the self-test unit to have complete control and communication capabilities during the self-test process. A wide-input DC-DC module is preferred to adapt to different input conditions.

[0016] Furthermore, the control module is specifically a microcontroller or a programmable logic controller, with a preset sequence of closing detection sections and an abnormal current threshold. When the current information collected by the sampling resistor increases abnormally and exceeds the threshold, the electronic switch module is controlled to quickly disconnect, and at the same time, the fault information is fed back to the shore power supply end through the communication optical fiber to realize fault location.

[0017] A self-testing and fault isolation method for an underwater power supply bus based on any of the aforementioned devices includes the following steps: S1, Reverse pre-power-on stage: The shore power supply end injects a low-power detection voltage into the bus. At this time, all electronic switches in the bus are in the open state and the bus is not conducting. S2, Sectional Closure Verification Stage: In this stage, the bus current flows from downstream to upstream. Starting from the downstream end of the bus, the control module controls the electronic switches of each detection unit to close segment by segment in a preset order. At the same time, the current detection module collects the bus current information of the corresponding section. The control module compares the collected current information with the preset anomaly judgment threshold. If the current is less than the threshold, it determines that there is no fault in the corresponding section and keeps the electronic switch closed to continue to perform closure verification on the upstream section. If the current exceeds the current anomaly threshold, it determines that there is a fault in the corresponding section, controls the electronic switch to quickly disconnect to isolate the faulty section, and feeds back the fault information to the shore power supply end through the communication fiber to realize fault location. During this stage, the bus current flows to trigger the reverse connection protection of the load branch power conversion unit, preventing the load from entering the working state. S3. Operation Exit Phase: When all sections are verified to be fault-free, the bus system enters the formal power-on working state, and the bus current flow direction is switched from upstream to downstream. At this time, the Zener diode of the auxiliary power module is forward-biased, the working conduction branch of the current detection module is turned on and the detection conduction branch is turned off, and the control module and DC-DC power supply unit exit the main circuit of the bus and do not participate in the energy transmission of the bus.

[0018] Furthermore, the low-power detection voltage mentioned in S1 is a medium-low voltage to avoid excessive inrush current during bus faults. The preferred medium-low voltage is 1000V.

[0019] Furthermore, in S2, the current flow direction of the busbar in this stage is from downstream to upstream. Starting from the downstream end of the busbar, the electronic switches of each detection unit are closed segment by segment by the control module in a preset sequence. Specifically: At this time, since the bus current flows from downstream to upstream, the Zener diode will be reverse-broken down, generating a constant voltage drop across its terminals. The DC-DC power supply unit converts the voltage drop across the Zener diode into a stable operating voltage required by the control module, thereby enabling the control module to enter the working state and acquire control and communication capabilities. After the control module enters the working state, it sends a control signal to the electronic switch to close it. At the same time, the control module feeds back the closing status information of the electronic switch in this section to the shore power supply terminal.

[0020] Furthermore, in S3, when the busbar is de-energized from the self-test state and re-energized to enter the normal working state, the self-locking electronic switch remains closed to ensure that the main circuit of the busbar is connected.

[0021] Furthermore, when maintenance and repair of a designated section of the busbar are required, the busbar is temporarily switched to reverse power supply mode while it is in the normal power-on working state, so that each inspection unit can be powered on again. The shore-based power supply unit sends a control signal to the self-test unit of the target section via a communication optical fiber, controlling its electronic switch to disconnect. Then the busbar is restored to the normal power supply state, the upstream busbar of the target section remains in normal operation, and the downstream busbar is disconnected, so as to realize the maintenance and repair of the designated section of the busbar.

[0022] Compared with the prior art, the beneficial effects of the present invention are: Implement a self-check of the busbar's status before power-on. Introduce a reverse pre-power-on self-check mechanism before the busbar is officially powered on to achieve rapid isolation of busbar faults and avoid the impact and system tripping risk caused by forced power-on with faults.

[0023] The system enables the location of busbar faults. The self-test process employs a segment-by-segment closure strategy, allowing the fault to be located within a specific busbar section. Remote status feedback can be achieved via fiber optic communication, providing a basis for subsequent repair work.

[0024] It has no impact on the load's operating status. During the busbar self-test phase, the current direction on the busbar is opposite to that during normal operation, which can trigger the reverse connection protection of the load branch power conversion unit. The load end does not enter the working state, and if there is a fault on the busbar, it will not affect the load.

[0025] The impact on the reliability of the power supply system is minimal. The self-testing and fault isolation device is only connected during the pre-testing stage and automatically disconnects from the main circuit after the busbar enters normal power supply, thus having no additional impact on the normal operation of the busbar and significantly improving the commissioning safety and engineering reliability of the underwater power supply system. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an underwater power supply system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the installation of a self-testing and fault isolation device for an underwater power supply bus according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the self-testing and fault isolation device for an underwater power supply bus according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the self-testing and fault isolation device for an underwater power supply bus according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the normal operation state of the self-testing and fault isolation device for an underwater power supply bus according to an embodiment of the present invention. In the diagram: 1. Shore-based power supply terminal; 2. Busbar; 3. Load branch power conversion unit; 4. Load; 5. Self-test unit; 6. Communication fiber optic cable; 50. Electronic switch; 51. Current detection module; 52. Auxiliary power supply module; 53. Control module; 510. Detection conduction branch diode; 511. Working conduction branch diode; 512. Sampling resistor; 520. Zener diode; 521. DC-DC power supply unit. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a self-testing and fault isolation device for an underwater power supply bus. The bus 2 is powered by a shore-based power supply terminal 1 and is used to supply power to a load 4. A load branch power conversion unit 3 is set between the bus 2 and the load 4. The self-testing and fault isolation device includes several self-testing units 5 and a communication optical fiber 6. Based on the current flow direction when the bus 2 is working normally, the upstream of the bus is defined as close to the shore-based power supply terminal 1, and the downstream of the bus is defined as far away from the shore-based power supply terminal 1. Several self-testing units 5 are arranged at intervals along the bus 2 and establish a communication connection with the shore-based power supply terminal 1 through the communication optical fiber 6. Several self-testing units 5 divide the bus 2 into multiple detection sections to realize segment-by-segment reverse pre-power-on self-testing and fault isolation of the bus 2. The self-test unit 5 includes an electronic switch module, a current detection module 51, an auxiliary power supply module 52, and a control module 53; The control module 53 is used to control the switching of the electronic switch module and identify current abnormalities, and to feed back the status of the electronic switch 50 to the shore power supply terminal 1 and remote controllable shutdown via the communication optical fiber 6. The electronic switch module is installed on busbar 2; The current detection module 51 is located downstream of the electronic switch module and is used to collect current change information during the closing process of the busbar 2 in the section in real time, so as to provide data for the current anomaly identification of the control module 53. The auxiliary power supply module 52 is used to provide stable operating power to each module of the self-test unit 5 during reverse pre-power-on self-test, and stops supplying power when the bus 2 is working normally.

[0029] Example 1: Please see Figures 1 to 2 The underwater power supply system includes: a shore-based power supply terminal 1, a busbar 2, a load branch power conversion unit 3, and a load 4. The shore-based power supply terminal 1 supplies power to the busbar, and the busbar 2 supplies power to the load 4. A load branch power conversion unit 3 is installed between the busbar and the load 4. In this embodiment, a self-testing unit 5 is installed entirely on the busbar 2. Multiple self-testing units 5, hereinafter referred to as nodes, are installed on the busbar 2, dividing the busbar 2 into multiple sections. All self-testing units 5 establish a communication connection with the shore-based power supply terminal 1 through an optical fiber 6. The communication optical fiber 6 is used to transmit status information and control signals.

[0030] See Figure 3 The self-test unit 5 is equipped with an electronic switch 50, a current detection module 51, an auxiliary power supply module 52, and a control module 53. The electronic switch 50 is located on the main power path of bus 2. Its input end is connected to the upstream bus. Based on the current flow direction when bus 2 is working normally, the upstream of bus 2 is defined as the power supply end 1 near the shore base, and the downstream of bus 2 is defined as the power supply end 1 far from the shore base. Its output end is connected to the downstream of bus 2, thereby realizing the connection and disconnection of the bus 2 circuit under the control of the control module 53.

[0031] The current detection module 51 is located downstream of the electronic switch 50 and is used to collect the current change signal during the reverse pre-power-on self-test phase of the bus 2. In this embodiment, the current detection module 51 includes a normal operation conduction branch and a current detection conduction branch. Both branches are preferably unidirectional conduction branches, wherein the normal operation conduction branch is the current path under normal operation of the bus 2, and the current detection conduction branch is the current path during the self-test phase of the bus 2; specifically, the normal operation conduction branch is a normal operation conduction branch diode 511, with the anode of the normal operation conduction branch diode 511 facing upstream of the bus and the cathode facing downstream of the bus; the detection conduction branch is a detection conduction branch diode 510 and a sampling resistor 512 connected in series, with the anode of the detection conduction branch diode 510 facing downstream of the bus and the cathode facing upstream of the bus, and the sampling resistor 512 is used for current information collection and limiting the current during the reverse pre-power-on self-test phase.

[0032] The auxiliary power supply module 52 is located inside the self-test unit 5, specifically downstream of the electronic switch 50. It includes a Zener diode 520 and a DC-DC power supply unit 521. The Zener diode 520 is directly connected in series with the bus 2 to obtain power during the reverse pre-power-on self-test phase. The DC-DC power supply unit 521 uses the voltage drop across the Zener diode 520 as its input and outputs the stable operating voltage required by the control module 53, etc.

[0033] The control module 53 is connected to the electronic switch 50, the current detection module 51, and the communication optical fiber 6, respectively, and is used to realize the closing control, status acquisition, and fault signal output in the pre-detection stage. In this embodiment, the control module 53 is preferably a microcontroller or a programmable logic controller, which has a preset segment closing sequence and current abnormality threshold.

[0034] Example 2: A self-testing and fault isolation method for an underwater power supply bus based on the device provided in Embodiment 1 includes: Busbar 2 self-test before power-on: In this embodiment, the working process of the device includes a reverse pre-power-on stage, a segment-by-segment closure verification stage, and an exit operation stage, thereby realizing rapid self-testing and fault isolation control of bus 2 before formal commissioning.

[0035] S1, Reverse pre-power-on stage: Before the busbar 2 system is officially powered on, the system first enters a reverse pre-power-on phase, where the shore-based power supply terminal 1 injects a low-power detection voltage into the busbar 2 link to establish pre-test conditions on the main trunk of busbar 2. At this time, all electronic switches 50 in busbar 2 are in the open state, and busbar 2 is not conductive. Next, the self-test system will perform segment-by-segment closure verification from the end of the busbar. In this embodiment, node B is used as an example.

[0036] S2, Segment-by-segment closure verification stage: See Figure 4 In self-test mode, the current flow on bus 2 is from downstream to upstream. The Zener diode 520 will be reverse-biased, generating a constant voltage drop across its terminals. The DC-DC power supply unit 521 converts the voltage drop across the Zener diode 520 into a stable operating voltage required by the control module 53, thus enabling the control module 53 to enter operating mode and acquire control and communication capabilities. After entering operating mode, the control module 53 will send a control signal to the electronic switch 50 according to a preset program, causing the electronic switch 50 to close. Simultaneously, the control module 53 feeds back the current node status information to the shore power supply terminal 1.

[0037] After the electronic switch 50 at node B is closed, the sampling resistor 512 feeds back the current information of bus 2 to the control module 53, which compares it with the current anomaly threshold. If the current is less than the current anomaly threshold, there is no fault in bus 2 between node B and node A, the electronic switch 50 at node B remains closed, and node A continues to perform the above operation. Conversely, if there is a short-circuit fault in bus 2 between node B and node A, the current will exceed the current anomaly threshold, the control module 53 will quickly disconnect the electronic switch 50, and feed back the fault information to the shore power supply terminal 1, thus realizing the diagnosis, isolation, and location of the short-circuit fault.

[0038] Throughout the self-test process, the current direction of bus 2 is opposite to that of normal operation. Due to the reverse connection protection function of the load power conversion device, load 4 cannot enter the working state and is disconnected from bus 2. Therefore, the voltage and current surge caused by the fault of bus 2 during the self-test process will not have an adverse effect on load 4.

[0039] S3, Exiting the running phase: Once the segment-by-segment closure verification is completed and the busbar 2 link status meets the commissioning conditions, the busbar 2 system enters the formal power-on operation phase. Because electronic switch 50 is a mechanically self-locking electronic switch, it will remain closed during the process of busbar 2 being de-energized from the self-test state and then re-energized to enter normal operation. (See also...) Figure 5 At this time, the current in bus 2 flows from upstream to downstream. The Zener diode 520 is forward-biased, and its voltage drop is negligible; therefore, self-test unit 5 is not operational. Simultaneously, the working conduction branch diode 511 is forward-biased, while the detection conduction branch diode 510 is reverse-biased and cut off. The current in bus 2 flows downstream through the channel formed by the working conduction branch diode 511, and the detection conduction branch is disconnected from bus 2. All self-test units 5 do not participate in the energy transfer of bus 2, do not introduce additional voltage drops or losses, and ensure that the power supply topology and operational reliability of bus 2 remain unchanged.

[0040] The low-power detection voltage mentioned in S1 is medium to low voltage to avoid excessive inrush current when bus 2 is faulty.

[0041] When maintenance is required on the circuit of node B, the controllable configuration of the conduction range of bus 2 can be achieved by controlling the shutdown of the designated node switch. Under normal operating conditions, bus 2 is briefly switched to reverse power supply mode. During this time, each inspection unit 5 is operational, possessing complete control and communication functions. The shore-based power supply terminal 1 sends a signal to the node B control module 53 via the communication fiber optic cable 6, controlling the node B electronic switch 50 to open. Then, forward power supply is restored. At this point, the upstream circuit of node B operates normally, and the downstream line of node B is disconnected. Maintenance and repair of downstream equipment and bus 2 can be performed without a large-scale, long-term power outage of upstream equipment. This achieves controllable control over the continuity range of bus 2.

[0042] In summary, this invention enables self-checking of the status of busbar 2 before power-on: by introducing a reverse pre-power-on self-checking mechanism before the formal voltage boosting of busbar 2, the line status is confirmed without the busbar 2 being subjected to rated operating voltage and high-power surges. When busbar 2 has short circuits, insulation breakdowns, or abnormal sections, these can be identified and isolated in a timely manner before formal power-on, avoiding the risk of system tripping caused by forced power-on with faults.

[0043] Achieving precise busbar fault location capabilities: The self-inspection process employs a segment-by-segment closure detection strategy. By sequentially conducting and detecting the continuity of two busbar sections, it transforms the busbar fault assessment from an overall assessment to a segment-level assessment. It can pinpoint the fault to the corresponding busbar section and remotely feed back the detection results, providing a clear basis for subsequent maintenance and restoration.

[0044] The self-test process has no adverse effect on the working state of load 4: During the reverse pre-power-on self-test phase of bus 2, the current direction in bus 2 is opposite to that in the normal power supply working state, which can trigger the reverse connection protection mechanism of the load branch power conversion unit 3, so that load 4 does not enter the working state; even if there is a fault in bus 2 during the self-test process, it will not inject energy into the downstream load 4, thereby avoiding the impact or damage to the load equipment caused by the abnormality of bus 2.

[0045] It has little impact on the normal operation of the power supply system and has high reliability: the device is connected to the power supply system only during the reverse pre-power-on self-test stage, and automatically exits after bus 2 completes the test and enters the normal power supply working state. It does not introduce additional conduction loss, voltage drop or potential failure points, and does not have an adverse effect on the electrical performance and system reliability of bus 2 in the long-term operation.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A self-testing and fault isolation device for an underwater power supply bus, wherein the bus is powered by a shore-based power supply terminal, the bus is used to supply power to a load, and a load branch power conversion unit is provided between the bus and the load, characterized in that, The self-testing and fault isolation device includes several self-testing units and communication optical fibers. Based on the current flow direction when the bus is working normally, the upstream of the bus is defined as the end close to the shore power supply and the downstream of the bus is the end far from the shore power supply. Several self-testing units are arranged at intervals along the bus and establish communication connection with the shore power supply through communication optical fibers. Several self-testing units divide the bus into multiple detection sections to realize segment-by-segment reverse pre-power-on self-testing and fault isolation at the bus section level. The self-test unit includes an electronic switch module, a current detection module, an auxiliary power supply module, and a control module; The control module is used to control the switching of the electronic switch module and identify current anomalies, and to feed back the status of the electronic switch to the shore power supply terminal and remote controllable shutdown via communication optical fiber. The electronic switch module is installed on the busbar; The current detection module is located downstream of the electronic switch module and is used to collect current change information during the closure process of the busbar in the section in real time, providing data for the current anomaly identification of the control module. The auxiliary power supply module is used to provide stable operating power to each module of the self-test unit during reverse pre-power-on self-test, and stops supplying power when the bus is working normally.

2. The self-testing and fault isolation device for an underwater power supply bus according to claim 1, characterized in that, The electronic switch module is specifically an electronic switch with a self-locking function.

3. The self-testing and fault isolation device for an underwater power supply bus according to claim 1, characterized in that, The current detection module includes a working conduction branch and a detection conduction branch connected in parallel on the busbar; The working conduction branch is a working conduction branch diode, with the anode of the working conduction branch diode facing upstream of the bus and the cathode facing downstream of the bus, providing a current path for the normal operation of the bus; The detection conduction branch consists of a detection conduction branch diode and a sampling resistor connected in series. The anode of the detection conduction branch diode faces downstream of the bus and the cathode faces upstream of the bus, providing a current path for the reverse pre-power-on self-test process. The sampling resistor is used for current information acquisition and limiting the current during the reverse pre-power-on self-test stage.

4. The self-testing and fault isolation device for an underwater power supply bus according to claim 1, characterized in that, The auxiliary power module includes a pre-power-on energy harvesting branch and a DC-DC power supply unit; The pre-energized power extraction branch is a Zener diode connected in series on the bus, with the anode of the Zener diode facing upstream of the bus and the cathode facing downstream of the bus. The DC-DC power supply unit converts the voltage drop generated by the reverse breakdown of the Zener diode during the reverse pre-power-on self-test phase into the stable operating voltage required by each module of the self-test unit.

5. The self-testing and fault isolation device for an underwater power supply bus according to claim 1, characterized in that, The control module is specifically a microcontroller or a programmable logic controller, with a preset sequence of closing detection sections and an abnormal current threshold.

6. A method for self-testing and fault isolation of an underwater power supply bus based on the device described in any one of claims 1-5, characterized in that, Includes the following steps: S1, Reverse pre-power-on stage: The shore power supply end injects a low-power detection voltage into the bus. At this time, all electronic switches in the bus are in the open state and the bus is not conducting. S2, Sectional Closure Verification Stage: In this stage, the bus current flows from downstream to upstream. Starting from the downstream end of the bus, the control module controls the electronic switches of each detection unit to close segment by segment in a preset order. At the same time, the current detection module collects the bus current information of the corresponding section. The control module compares the collected current information with the preset anomaly judgment threshold. If the current is less than the threshold, it determines that there is no fault in the corresponding section and keeps the electronic switch closed to continue to perform closure verification on the upstream section. If the current exceeds the current abnormal threshold, it is determined that there is a fault in the corresponding section. The electronic switch is quickly disconnected to isolate the faulty section, and the fault information is fed back to the shore power supply end through the communication fiber to realize fault location. During this stage, the direction of the bus current flow triggers the reverse connection protection set in the power conversion unit of the load branch, preventing the load from entering the working state. S3. Operation Exit Phase: When all sections are verified to be fault-free, the bus system enters the formal power-on working state, and the bus current flow direction is switched from upstream to downstream. At this time, the Zener diode of the auxiliary power module is forward-biased, the working conduction branch of the current detection module is turned on and the detection conduction branch is turned off, and the control module and DC-DC power supply unit exit the main circuit of the bus and do not participate in the energy transmission of the bus.

7. The self-inspection and fault isolation method for underwater power supply bus according to claim 6, characterized in that, The low-power detection voltage mentioned in S1 is a medium-low voltage.

8. The self-inspection and fault isolation method for underwater power supply bus according to claim 6, characterized in that, In S2, the current flow direction of the busbar in this stage is from downstream to upstream. Starting from the downstream end of the busbar, the electronic switches of each detection unit are closed segment by segment by the control module in a preset sequence. Specifically: At this time, the bus current flows from downstream to upstream of the bus. The Zener diode will be reverse-broken down, generating a constant voltage drop across the Zener diode. The DC-DC power supply unit converts the voltage drop across the Zener diode into a stable operating voltage required by the control module, thereby enabling the control module to enter the working state and have control and communication capabilities. After the control module enters the working state, it sends a control signal to the electronic switch to close the electronic switch. At the same time, the control module feeds back the closing status information of the electronic switch in this section to the shore power supply terminal.

9. The self-inspection and fault isolation method for underwater power supply bus according to claim 6, characterized in that, In S3, when the busbar is de-energized from the self-test state and re-energized to enter the normal working state, the self-locking electronic switch remains closed.

10. The self-inspection and fault isolation method for underwater power supply bus according to claim 6, characterized in that, When maintenance and repair of a designated section of the busbar are required, the busbar should be briefly switched to reverse power supply mode while it is in the normal power-on working state, so that each inspection unit can be powered on again. The shore-based power supply unit sends a control signal to the self-test unit of the target section via a communication optical fiber, controlling its electronic switch to disconnect. Then the busbar is restored to the normal power supply state, the upstream busbar of the target section remains in normal operation, and the downstream busbar is disconnected, so as to realize the maintenance and repair of the designated section of the busbar.

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