Annular direct-current busbar power system used in ship dynamic positioning mode

Abstract

The utility model discloses an annular DC busbar power system used in a ship dynamic positioning mode. According to the annular direct-current busbar power system provided by the utility model, due to the networking form of the annular direct-current busbar, the system has more flexible and rapid protection performance, that is, before a ship power grid is affected by faults, the frequency converter can rapidly detect abnormal conditions and actively complete isolation of fault points, so that the whole power grid and normal branches are not affected, and the reliability of the ship power grid is improved. And after the fault is eliminated, normal connection is quickly recovered. The variable-speed generator set is adopted in the system, the speed regulation range of the variable-speed generator set is expanded, the variable-speed generator set can automatically regulate the running speed according to loads, and load oil consumption can be always kept within an economic range, so that oil is saved, emission is reduced, the energy efficiency utilization rate of the generator set is remarkably improved, and the flexibility of the system is improved. The method is more suitable for ships with ship dynamic positioning working condition requirements.

Description

Technical Field

[0001] This utility model relates to the field of ship propulsion power system technology, specifically to a ring DC busbar power system for ship dynamic positioning mode. Background Technology

[0002] For large offshore platforms and offshore maintenance vessels, automatic dynamic positioning (DP) capability is required during offshore operations to ensure attitude stability and operational safety. Currently, dynamic positioning (DP) technology is relatively mature, and various power system configuration schemes have been developed based on different ship dynamic positioning level requirements. Among them, closed-loop power grid operation has advantages such as better energy conservation and emission reduction, lower operating costs, and increased safety and reliability, and has become the industry's first choice. However, the safety and reliability of the power grid under DP conditions also face severe challenges. Each classification society has increasingly higher requirements for the protection system of closed busbar operation. For example, for DP2 vessels, the ABS classification society requires simulated short-circuit tests to verify the fault ride-through capability of the power system.

[0003] Patent application CN117613832A discloses a shipboard DC ring network system and its selective short-circuit protection method for bus tie switches. The system includes a DC main distribution board, a test distribution board, and multiple bus tie switches connected by cables to form a ring network. The method utilizes a high-speed current sampling unit in the bus tie switch controller to collect the transient current value and direction output by the solid-state switches in the bus tie switch cabinet in real time, determine the occurrence of a short circuit, and quickly respond to provide selective protection. Patent CN209150720U discloses a "DC ring network electric propulsion system" comprising several ring DC busbar modules, several bus tie circuit breakers, several power supply branches, and several power consumption branches. The power supply branches and the ring DC busbar modules correspond one-to-one. The ring DC busbar modules are connected end-to-end to form a ring network. Each ring DC busbar module includes ring DC busbars and bus tie circuit breakers connected in series, with each pair of adjacent ring DC busbars connected in series with a bus tie circuit breaker. This utility model uses three ring-shaped DC busbars connected in a ring shape. When any one ring-shaped DC busbar fails and is isolated from the other two ring-shaped DC busbars, the other two ring-shaped DC busbars are still connected to each other, thus improving the system reliability.

[0004] However, once a short-circuit fault occurs in the ship's ring DC bus power system, the DC bus voltage drops rapidly, triggering fault protection and rendering the equipment in the system inoperable. Furthermore, short-circuit faults in the ring bus are prone to propagation, leading to a complete power outage across the entire grid. To address these issues, this invention provides a ring DC bus power system and control method for ship dynamic positioning mode, which offers higher integrity and fault tolerance than traditional segmented bus operation, effectively ensuring the safety and reliability of the entire ship's operation. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a ring DC bus power system for ship dynamic positioning mode.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: a ring DC bus power system for ship dynamic positioning mode, including n sets of variable speed generator sets, lithium battery packs, ring DC bus, at least two load units and a monitoring center;

[0007] The ring DC busbar includes n+1 main busbars and n-1 branch busbars. The n main busbars are connected to n sets of variable speed generators and lithium battery packs in sequence. The n+1 main busbars are connected to the ends of the 1st main busbar and the nth main busbar. The ring DC busbar is equipped with a first circuit breaker and a monitoring component.

[0008] One end of each of the n-1 busbar branch lines is connected sequentially to the node between the first circuit breaker and the monitoring component in the first n-1 busbar main lines, and the other end is connected to the (n+1)th busbar main line. The (n+1)th busbar main line is also sequentially equipped with a second circuit breaker and a monitoring component. Each busbar branch line is equipped with a third circuit breaker. In the dynamic positioning mode, the third circuit breakers on all busbar branch lines are open, while all second circuit breakers on the busbar main lines remain closed. The monitoring component includes, in sequence, a current sensor 1, an IGBT solid-state switch, a current sensor 2, and a mechanical switch.

[0009] The variable speed generator set includes a variable speed generator connected in sequence to a ring DC bus, a fourth circuit breaker, a first AC / DC module, and a first current sensor; the lithium battery pack is equipped with multiple lithium battery clusters, a fifth circuit breaker, a rectifier inverter AC / DC module, and a second current sensor.

[0010] The load unit is connected to the main busbar; the load unit includes a third current sensor, an inverter frequency converter module, a load circuit breaker, and a propulsion device; the inverter frequency converter module includes a DC / AC module and an inverter circuit breaker; the propulsion device includes a propulsion motor and a propeller, and the load unit also includes daily loads;

[0011] The variable speed generator set and lithium battery pack provide power to the load unit through a ring DC bus, and the monitoring center is used for system operation monitoring and fault handling.

[0012] As a preferred embodiment, the monitoring center includes a monitoring platform and a monitoring subsystem S-Link, used for operation control, process monitoring and fault handling of the ring DC bus power system; the monitoring platform includes control devices, communication and conduction equipment, monitoring and alarm system, cloud server and remote client.

[0013] As a preferred embodiment, the control device includes a power distribution system (PMS), several propulsion control modules, and an integrated power distribution module. The integrated power distribution module is equipped with an energy management subsystem (EMS) and adopts a distributed layout structure according to the needs of different monitoring domains and a hierarchical control mode of main control and sub-control, so as to meet the requirements of the dynamic positioning mode.

[0014] As a preferred embodiment, the Power Distribution System (PMS) monitors and controls the operating status of the power system in real time, including various parameters of the power system, to reduce system downtime caused by equipment failure or abnormal parameters. It features fault alarm and notification functions, promptly alerting and recording fault information when a fault occurs. This information is then analyzed and processed by the monitoring subsystem S-Link to promptly detect and address potential faults and anomalies. The monitoring subsystem S-Link mainly consists of data acquisition, data flow display, and data expansion modeling. The ship's end monitoring station S-Link host performs data acquisition, data integration, and data flow. Data sources include variable-speed generator sets, lithium battery packs, monitoring and alarm systems, and communication and navigation equipment.

[0015] The integrated power distribution module is equipped with a main controller PLC, a switch and a sub-controller for each load unit. When one of the current sensors 1 and 2 at a certain location generates an overcurrent, it indicates a short circuit fault. The corresponding monitoring components transmit information to the main controller PLC of the integrated power distribution module, and the main controller PLC controls the shutdown of relevant components on the ring DC bus.

[0016] As a preferred embodiment, the communication and navigation equipment is used to acquire ship navigation information, and the monitoring and alarm system is used to monitor the operating status of the power system. The energy management subsystem (EMS) of the integrated power distribution module manages energy according to the load conditions, automatically adjusting the speed of each variable speed generator and the number of variable speed generator units on the grid, so that the output power of the variable speed generator unit matches the load power, thereby optimizing the fuel consumption of the variable speed generator unit.

[0017] The beneficial effects of this utility model are:

[0018] 1. The ring DC bus power system for ship dynamic positioning provided by this utility model has more flexible and rapid protection performance due to its ring DC bus networking form. That is, before the ship's power grid is affected by a fault, the frequency converter can quickly detect the abnormal situation and actively isolate the fault point, so that the entire power grid and normal branches are not affected. After the fault is eliminated, the normal connection is quickly restored.

[0019] 2. The use of variable speed generator sets expands the speed regulation range. The variable speed generator set can adjust the operating speed according to the load, and will always keep the load fuel consumption within the economic range, thereby saving fuel and reducing emissions. This significantly improves the energy efficiency of the generator set and increases the flexibility of the system, making it more suitable for ships with dynamic positioning requirements.

[0020] 3. The system provided by this utility model can also connect to various energy storage devices such as lithium batteries and capacitors, expanding the power station capacity and adding more load adjustment points. Simultaneously, it can increase the upper limit of the generator set's power and provide higher single-point safety. Furthermore, the battery pack can perform peak shaving and valley filling functions. When the generator power is redundant, it charges the lithium batteries to recover energy; when the generator set's load is insufficient, the lithium batteries discharge to supplement it. This effectively improves energy utilization, smooths the load curve, increases the unit's load rate, reduces losses from frequent generator start-stop cycles, and stabilizes grid operation.

[0021] 4. Develop a selective short-circuit protection device and method for the DC ring network bus tie switch of a ship. Compared with mechanical circuit breaker protection, it reduces the false judgment rate of non-fault points of the DC ring network bus tie and has higher integrity and fault tolerance than the traditional segmented busbar operation. It plays a vital role in the safety and reliability of the entire ship operation. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the system composition of this utility model;

[0023] Figure 2 This is a single-line diagram illustrating a system of this utility model;

[0024] Figure 3 This is a diagram showing the configuration of the monitoring components of this utility model;

[0025] Figure 4 This is a diagram illustrating the control system composition of this utility model;

[0026] Figure 5 This is a connection diagram of the control device of this utility model;

[0027] Figure 6 This is a system control flowchart of the present invention;

[0028] In the picture:

[0029] 1-Variable speed generator set, 2-Lithium battery pack, 3-Ring DC busbar, 4-Load unit, 5-Monitoring center; 110-Variable speed generator, 111-Fourth circuit breaker, 120-First AC / DC module, 122-First current sensor;

[0030] 210 - Lithium battery cluster, 221 - Fifth circuit breaker, 222 - Second current sensor;

[0031] 310-Busbar main line, 320-Busbar branch line, 330-Third circuit breaker, 311-First circuit breaker, 312-Monitoring component, 312a-Current sensor one, 312b-Solid-state switch, 312c-Current sensor two, 312d-Mechanical switch;

[0032] 410-DC / AC module, 420-propulsion device, 411-third current sensor, 415-load circuit breaker, 421-propulsion motor, 425-propulsion unit;

[0033] 50-Monitoring platform, 50a-Monitoring subsystem S-Link, 510-Control device, 520-Communication and communication equipment, 530-Monitoring and alarm system, 540-Cloud server, 550-Remote client.

[0034] 511-Power Distribution System (PMS), 512-Control Module, 513-Integrated Power Distribution Module. Detailed Implementation

[0035] The specific implementation scheme of this utility model will now be described in detail with reference to the accompanying drawings.

[0036] like Figure 1-6 As shown, a ring DC bus power system for ship dynamic positioning mode includes n sets of variable speed generator sets 1, lithium battery packs 2, ring DC bus 3, at least two load units 4, and a monitoring center 5.

[0037] The ring-shaped DC busbar 3 includes a main busbar 310 and several branch busbars 320. The main busbar 310 is connected to n sets of variable speed generator sets 1 and lithium battery packs 2. The variable speed generator sets 1 and lithium battery packs 2 provide power to the load unit 4 through the ring-shaped DC busbar 3. The monitoring center 5 is used for monitoring the system operation process and handling faults to ensure the safe and stable operation of the system.

[0038] The ring-shaped DC busbar 3 includes n+1 busbar main lines 310 and n-1 busbar branch lines 320. The n busbar branch lines are connected in sequence to n sets of variable speed generator sets 1 and lithium battery sets 2. The n+1 busbar main line is connected to the ends of the first busbar main line and the nth busbar main line. The ring-shaped DC busbar main line is equipped with a first circuit breaker 311 and a monitoring component 312.

[0039] One end of each of the n-1 busbar branch lines 320 is sequentially connected to the node between the first circuit breaker 311 and the monitoring component 312 in the first n-1 busbar main lines, and the other end is connected to the (n+1)th busbar main line. The (n+1)th busbar main line is also sequentially equipped with a second circuit breaker and a monitoring component. Each busbar branch line 320 is equipped with a third circuit breaker 330. In the dynamic positioning mode, the third circuit breakers of all busbar branch lines are open, and all second circuit breakers on the busbar main line remain closed. The monitoring component 312 includes a current sensor 312a, an IGBT solid-state switch 312b, a current sensor 312c, and a mechanical switch 312d connected in sequence.

[0040] The solid-state switch 312b used in monitoring component 312 is mainly turned on and off by the upper transistor of the IGBT half-bridge, while the lower transistor is always in the off state. The current across the solid-state switch is detected by current sensor 312a and current sensor 312c. When an overcurrent occurs, it indicates a short circuit fault. The system automatically shuts down all IGBTs inside the module and reports the fault information to the PLC of the integrated power distribution module. The module on the opposite side of the same solid-state switch is shut down. After a short delay, the mechanical switch 312d is shut down, enabling the entire system to autonomously isolate the fault momentarily. The specific process is as follows: overcurrent interruption, IGBT overcurrent protection, current module IGBT shutdown, PLC receives the fault and notifies the remaining modules on the ring DC bus 3 to shut down their IGBTs and open their mechanical switches. The entire process has a rapid response time, the main line voltage of the ring DC bus will not drop significantly, and the current will continue for a sufficient time to ensure that the circuit breaker or fuse in the load circuit can be selectively triggered.

[0041] The ring DC busbar 3 is formed by the main busbar 310 and the branch busbar 320, which is beneficial to isolate the fault point and avoid the entire power grid from being affected by a single fault point. Under the dynamic positioning mode (DP2 or DP3) operating condition, all branch busbars 320 are disconnected and the main busbar 210 remains closed.

[0042] The variable speed generator set 1 includes a variable speed generator 110, a fourth circuit breaker 111, a first AC / DC module 120, and a first current sensor 122, all connected in sequence to the ring DC bus 3. The lithium battery pack 2 is equipped with multiple lithium battery clusters 210, a circuit breaker 221, a rectifier-inverter AC / DC module 220, and a second current sensor 222. Once an abnormality is detected, the first AC / DC module 120 uses the inverter power electronic devices to control the power of the variable speed generator 110, and simultaneously starts the backup generator or connects to the lithium battery pack 2 to quickly compensate for grid fluctuations.

[0043] Load unit 4 is connected to busbar main line 310; load unit 4 includes a third current sensor 411, inverter frequency converter module, load circuit breaker 415 and propulsion device 420; inverter frequency converter module includes DC / AC module 410 and inverter circuit breaker 412; propulsion device 420 includes propulsion motor 421 and propeller 425, and load unit 4 also includes daily load.

[0044] This power system adopts a DC grid configuration. The variable speed generator 110 and propulsion device 420 are separated from the ring DC bus 3 through the first AC / DC module 120 and DC / AC module 410. The monitoring center 5 regulates the start and stop of the variable speed generator 110 and propulsion device 420 in an automated control manner, which fully ensures that when the ship experiences a short circuit fault in dynamic positioning (DP2 or DP3) mode, it can quickly detect and disconnect the fault.

[0045] like Figure 4 and Figure 5 As shown, the monitoring center 5 includes a monitoring platform 50 and a monitoring subsystem S-Link 50a, which are used for operation control, process monitoring and fault handling of the ring DC bus power system; the monitoring platform 50 includes a control device 510, a communication device 520, a monitoring alarm system 530, a cloud server 540 and a remote client 550.

[0046] The control device 510 includes a power distribution system PMS 511, a propulsion control module 512, and an integrated power distribution module 513. The integrated power distribution module 513 is equipped with an energy management subsystem EMS, and according to the needs of different monitoring domains, such as the port or starboard engine room, generator set, battery pack, and ring DC bus, it adopts a distributed layout structure according to the hierarchical control mode of main control and sub-control to meet the requirements of dynamic positioning mode.

[0047] The power distribution system PMS511 monitors and controls the operating status of the power system in real time, including various parameters of the power system, in order to reduce system downtime caused by equipment failure or abnormal parameters. It has fault alarm and prompt functions, and promptly alarms when a fault occurs and records fault information for the monitoring subsystem (S-Link) 50a to analyze and process it, so as to promptly detect and deal with potential faults and abnormal situations.

[0048] The integrated power distribution module 513 is equipped with a main controller PLC, a switch and a sub-controller for each load unit 4;

[0049] When one of the current sensors 312a and 312c at a certain location generates an overcurrent, it indicates a short circuit fault. The corresponding monitoring component 312 transmits information to the main controller PLC of the integrated power distribution module 513, and the main controller PLC controls the shutdown of relevant components on the ring DC bus 3.

[0050] The communication and navigation equipment 520 is used to acquire ship navigation information, and the monitoring and alarm system 530 is used to monitor the system's operating status. The energy management subsystem EMS manages energy according to the load conditions, automatically adjusting the speed of each variable speed generator 110 and the number of variable speed generator 110 units on the grid, so that the output power of the variable speed generator set 1 matches the load power, thereby optimizing the fuel consumption of the variable speed generator set 1 and saving ship operating costs.

[0051] The monitoring subsystem S-Link50a mainly consists of data acquisition, data flow and display, and data expansion modeling. The ship's end monitoring station S-Link host performs data acquisition, data integration, and data flow. The data sources include the ship's power system, monitoring and alarm system, and communication and navigation equipment.

[0052] For example, S-Link can acquire and store ship operation status data from the propulsion device 420, control device 510, communication and navigation device 520, monitoring and alarm system 530 of the load unit 4 through communication equipment, and upload it to the cloud server 540. The S-Link subsystem 50a can realize cross-regional and cross-platform display of collected data, remote data backtracking, data modeling and remote fault analysis. Users can log in with an account on a WEB browser through the remote client 550 and view the latest ship status and operation data in real time.

[0053] The aforementioned ring DC bus power system uses variable speed generators 110, which can adjust or add multiple generator speed points according to actual tests, thereby expanding the power station capacity adjustment capability. This allows the variable speed generator set 1 to operate with better fuel economy, which is more advantageous than traditional generator sets. If there are n variable speed generators 110, each with m output power levels, the power station capacity adjustment capability will increase to (n*m) levels.

[0054] For ships operating under DP (Power Distribution) conditions, in addition to using DC grid-connected variable speed generator sets, various energy storage devices such as lithium battery packs and capacitors can be connected. This not only increases the power station's capacity range (raising the upper limit of the variable speed generator set's power) but also expands the power station's capacity adjustment points, i.e., increases the number of load adjustment points (number of speed settings).

[0055] Let the capacity of each variable-speed generator set be Qi, and the capacity of each lithium battery pack be Qj. For a power station equipped with n variable-speed generators, each with m output power levels, and connected to k lithium battery packs, its total capacity is:

[0056]

[0057] The power plant capacity QF adjustment range is:

[0058] When Qjmin < Qimin, Qjmin ≤ QF ≤ QZ;

[0059] When Qjmin>Qimin, Qimin≤QF≤QZ;

[0060] When using pure battery packs for power supply, the total number of power station capacity adjustment points is [(n*m)+1] levels;

[0061] The integration of lithium battery packs not only provides single-point system security but also serves the purpose of peak shaving and valley filling. When generator power is redundant, lithium batteries are charged to recover energy and absorb power during valleys. When the generator load is insufficient, lithium batteries are discharged to supplement (peak shaving). This can effectively improve energy utilization, smooth the load curve, increase the generator load rate, reduce losses from frequent generator start-stops, and stabilize grid operation.

[0062] The aforementioned ring-shaped DC bus power system has a monitoring center 5 capable of monitoring and handling three types of system faults, including equipment overheating or overspeeding, current overload, and bus short circuit. For relatively controllable faults such as equipment overheating or overspeeding, the system maintains its operating state and alarms by triggering an overcurrent warning current in the power module, or it stops the system after an emergency speed reduction to complete the protection action. For equipment problems with more severe current overload, the equipment triggers a long-delay protection current with a protection response speed of 10s (configurable, with the frequency converter module cutting off the current). For equipment problems with extremely severe bus short circuits, the equipment triggers a short-delay protection current, requiring rapid protection with a protection response speed of 10μs (frequency converter module switching circuit).

[0063] Before a fault affects the ship's electrical network, the system can quickly detect anomalies and proactively isolate the fault point, ensuring that the entire power grid and normal branches remain unaffected. After the fault is cleared, normal connections are quickly restored. The DC ring network configuration provides the system with greater flexibility and further enhances the safety and reliability of the power grid under DP conditions.

[0064] like Figure 6 As shown, the control method for the ring DC bus power system in the ship's dynamic positioning mode includes the following steps:

[0065] Step 1: Start the diesel generator set

[0066] When the variable speed generator 110 starts running, the system performs a self-check. If the system reports an error and sends the error information to the monitoring terminal, maintenance personnel can use the remote control system to shut down all variable speed generators 110 and perform maintenance on the variable speed generators 110; otherwise, it will enter normal operation.

[0067] Step 2: Pre-charge the toroidal DC bus

[0068] After the variable speed generator 110 is running normally, it charges the ring DC bus 3 through the first AC / DC module 120, and the monitoring component 312 works to perform the corresponding monitoring tasks; if a fault occurs, proceed to step three, otherwise proceed to step four.

[0069] Step 3: Troubleshooting the Ring DC Bus

[0070] When a short-circuit fault occurs in the system, the fault isolation method includes the following steps:

[0071] S31: Overcurrent Monitoring

[0072] The n+1 busbar main line 310 of the ring DC busbar 3 is monitored by the monitoring component 312 on it through the current sensor 312a and the current sensor 312c to monitor the overcurrent of the current busbar main line of the ring DC busbar 3 until the set value is detected.

[0073] S32: Overcurrent protection

[0074] When an overcurrent occurs, the IGBT module on the main busbar 310 section automatically shuts off for overcurrent protection and trips the mechanical switch 312d. At the same time, the PLC of the integrated power distribution module 513 sends overcurrent information.

[0075] S33: Fault information processing. When the main controller PLC of the integrated power distribution module 513 receives the fault information, it notifies the remaining IGBT modules on the ring DC bus 3 to turn off and the corresponding mechanical switches to open.

[0076] S34: After the fault is resolved, proceed to step two;

[0077] Step 4: Start the load operation

[0078] After the ring DC busbar 3 is pre-charged, it begins to supply power to the load unit 4; the DC power is converted into AC power required by the propulsion motor 421 and the daily load through the DC / AC module 410 respectively; at the same time, the power system performs a self-check. If the power supply requirements are met, power is supplied to the daily load and the propulsion motor respectively, and step five is executed; otherwise, step six is ​​executed.

[0079] Step 5: System operation status monitoring and adjustment

[0080] The power distribution system PMS511 performs power distribution to each variable speed generator 110 in the variable speed generator set 1 and performs fault diagnosis and repair on the DC system. When a short circuit fault signal is received in the DC system, step three is executed; when a power-down command is received, step six is ​​executed; otherwise, step five is repeated.

[0081] Step Six: End Judgment

[0082] Power off to terminate system operation.

[0083] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some examples of its application, and are not intended to limit the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements are all within the protection scope of the present invention.

Claims

1. A ring DC bus power system for ship dynamic positioning mode, comprising n sets of variable speed generator sets (1), lithium battery packs (2), ring DC bus (3), at least two load units (4), and a monitoring center (5); Its features are: The ring DC busbar (3) includes n+1 busbar main lines (310) and n-1 busbar branch lines (320), wherein the n busbar branch lines are connected in sequence to n sets of variable speed generator sets (1) and lithium battery sets (2), and the n+1 busbar main line is connected to the ends of the first busbar main line and the nth busbar main line. The ring DC busbar main line is equipped with a first circuit breaker (311) and a monitoring component (312). One end of each of the n-1 busbar branch lines (320) is connected sequentially to the node between the first circuit breaker (311) and the monitoring component (312) in the first n-1 busbar main lines, and the other end is connected to the n+1 busbar main line; the n+1 busbar main line is also sequentially equipped with a second circuit breaker and a monitoring component; each busbar branch line (320) is equipped with a third circuit breaker (330); in the dynamic positioning mode, the third circuit breakers of all busbar branch lines are open, and all second circuit breakers on the busbar main line remain closed; the monitoring component (312) includes a current sensor (312a), an IGBT solid-state switch (312b), a current sensor (312c), and a mechanical switch (312d) connected sequentially; The variable speed generator set (1) includes a variable speed generator (110), a fourth circuit breaker (111), a first AC / DC module (120), and a first current sensor (122) connected in sequence to the ring DC bus (3); the lithium battery pack (2) is provided with multiple lithium battery clusters (210), a fifth circuit breaker (221), a rectifier frequency converter AC / DC module (220), and a second current sensor (222); The load unit (4) is connected to the main busbar (310); the load unit (4) includes a third current sensor (411), an inverter frequency converter module, a load circuit breaker (415) and a propulsion device (420); the inverter frequency converter module includes a DC / AC module (410) and an inverter circuit breaker (412); the propulsion device (420) includes a propulsion motor (421) and a propeller (425), and the load unit (4) also includes daily loads; n sets of variable speed generator sets (1) and lithium battery packs (2) provide power to the load unit (4) through a ring DC bus (3), and the monitoring center (5) is used for system operation monitoring and fault handling.

2. A ring DC bus power system for ship dynamic positioning mode as described in claim 1, characterized in that: The monitoring center (5) includes a monitoring platform (50) and a monitoring subsystem S-Link (50a), which are used for operation control, process monitoring and fault handling of the ring DC bus power system; the monitoring platform (50) includes a control device (510), a communication device (520), a monitoring alarm system (530), a cloud server (540) and a remote client (550).

3. A ring DC bus power system for ship dynamic positioning mode as described in claim 2, characterized in that: The control device (510) includes a power distribution system (PMS) (511), several propulsion control modules (512), and an integrated power distribution module (513). The integrated power distribution module (513) is equipped with an energy management subsystem (EMS) and adopts a distributed layout structure according to the needs of different monitoring domains and the hierarchical control mode of main control and sub-control, so as to meet the requirements of the dynamic positioning mode.

4. A ring DC bus power system for ship dynamic positioning mode as described in claim 3, characterized in that: The power distribution system PMS (511) monitors and controls the operating status of the power system in real time, including various parameters of the power system, in order to reduce system downtime caused by equipment failure or abnormal parameters. It has fault alarm and prompt functions, and promptly alarms and records fault information when a fault occurs. The monitoring subsystem S-Link (50a) analyzes and processes it, and promptly detects and handles potential faults and abnormal situations. The monitoring subsystem S-Link (50a) mainly consists of data acquisition, data flow display, and data expansion modeling. The ship end monitoring station S-Link host performs data acquisition, data integration, and data flow. The data sources include variable speed generator set (1), lithium battery pack (2), monitoring alarm system (530), and communication and navigation equipment (520). The integrated power distribution module (513) is equipped with a main controller PLC, a switch and a sub-controller for each load unit (4); when one of the current sensor 1 (312a) and current sensor 2 (312c) at a certain location generates an overcurrent, it indicates that a short circuit fault has occurred. The corresponding monitoring component (312) transmits information to the main controller PLC of the integrated power distribution module (513), and the main controller PLC controls the relevant components on the ring DC bus (3) to shut down.

5. A ring DC bus power system for ship dynamic positioning mode as described in claim 4, characterized in that: The communication and navigation equipment (520) is used to acquire ship navigation information, and the monitoring and alarm system (530) is used to monitor the operating status of the power system. The energy management subsystem (EMS) of the integrated power distribution module (513) performs energy management according to the load conditions, automatically adjusts the speed of each variable speed generator (110) and the number of variable speed generators (110) on the grid, so that the output power of the variable speed generator set (1) matches the load power, thereby optimizing the fuel consumption of the variable speed generator set (1).

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