A control method and system for a marine hybrid power system

Abstract

This invention discloses a control method and system for a marine hybrid power system. The control method includes: receiving operating commands sent by a user; the operating commands include: a command to start and connect all lithium battery packs to the grid, a command to start and charge all lithium battery packs, and a command to disconnect all lithium battery packs; executing a control method for starting and discharging lithium battery packs according to the command to start and connect all lithium battery packs to the grid; executing a control method for starting and charging lithium battery packs according to the command to start and charge all lithium battery packs; and executing a control method for disconnecting lithium battery packs according to the command to disconnect all lithium battery packs. The technical solution of this invention, by controlling the starting, grid connection, charging, discharging, and shutdown disconnection of multiple lithium battery packs according to the operating commands sent by the user, thereby realizing the functions of starting and connecting multiple lithium battery packs to the grid and discharging them into the AC power grid, charging multiple lithium battery packs from the AC power grid, and shutting down and disconnecting multiple lithium battery packs in a hybrid power ship.

Description

Technical Field

[0001] This invention relates to the field of marine technology, and in particular to a control method and system for a marine hybrid power system. Background Technology

[0002] Hybrid power ships using AC power systems typically connect their energy storage battery systems to the ship's AC power grid via lithium battery charging inverters. When the installed capacity of the hybrid power ship's energy storage batteries is large, the entire ship's energy storage battery system needs to be divided into multiple battery groups that are independently connected to the ship's power grid. Therefore, a method is needed to control multiple battery groups together, enabling them to start, connect to the grid, charge, discharge, and disconnect from the grid during shutdown.

[0003] Existing technical solutions are mostly aimed at improving the balancing effect of battery packs in marine hybrid power systems, and achieving an increase in the balance of power battery packs. However, they do not involve control methods for starting, connecting to the grid, charging, discharging, and disconnecting multiple battery packs during shutdown. Summary of the Invention

[0004] This invention provides a control method and system for a marine hybrid power system. By controlling the starting, grid connection, charging, discharging, and shutdown / disconnection of multiple battery packs, the system enables the multiple lithium battery packs of a hybrid power ship to start and connect to the grid and discharge to the AC power grid, the AC power grid to charge the multiple lithium battery packs, and the multiple lithium battery packs to shut down and disconnect.

[0005] According to one aspect of the present invention, a control method for a marine hybrid power system is provided, characterized in that the control method includes:

[0006] Receive operating instructions sent by the user; the operating instructions include: all lithium battery pack start-up and grid connection instructions, all lithium battery pack start-up and charging instructions, and all lithium battery pack disconnection instructions;

[0007] The control method for starting and discharging lithium battery packs according to all lithium battery pack start-up and grid-connection commands;

[0008] A control method for executing lithium battery pack start-up charging based on all lithium battery pack start-up charging commands;

[0009] The control method for executing the de-listing of lithium battery packs according to the command to de-list all lithium battery packs.

[0010] Optionally, the control method for starting and discharging the lithium battery pack specifically includes:

[0011] Confirm that the power switch of each lithium battery pack is in the open state, each charging inverter is ready, and the shore power switch is not in operation.

[0012] If all lithium battery pack start-up and grid connection commands are received and the start-up and grid connection conditions are met, then control the first lithium battery pack to start up and connect to the grid.

[0013] Determine whether the first lithium battery pack has been successfully connected to the grid. If successful, send a signal indicating that the first lithium battery pack has started successfully and continue with the steps to start the subsequent lithium battery packs; otherwise, send a signal indicating that the first lithium battery pack has failed to start.

[0014] After starting each lithium battery pack in sequence, determine whether at least one lithium battery pack is running. If so, return the grid-connected lithium battery pack number; otherwise, return a lithium battery system start-up failure signal.

[0015] The lithium battery pack that was successfully started provides power to the ship.

[0016] Optionally, it is determined whether the first lithium battery pack has been successfully connected to the grid. If successful, a start-up success signal for the first lithium battery pack is sent, and the steps to start the subsequent lithium battery packs are continued; otherwise, a start-up failure signal for the first lithium battery pack is sent, including:

[0017] Determine if the State of Charge (SOC) of the first lithium battery pack is greater than the preset SOC. If so, proceed to the next step; otherwise, report a signal indicating that the first lithium battery pack has insufficient power and the grid connection has failed.

[0018] Send a signal indicating that other lithium battery packs / units are on the grid to the charging inverter;

[0019] Send a discharge mode command to the charging inverter;

[0020] Determine if the charging inverter device returns a discharge mode signal. If yes, proceed to the next step; otherwise, return a discharge mode switching failure and grid connection failure signal.

[0021] Send a start command to the charging inverter;

[0022] Determine if the charging inverter has started running. If it has, proceed to the next step; otherwise, repeat the start command twice more. If all three start attempts fail, an alarm will be triggered.

[0023] Send a grid connection command to the charging inverter;

[0024] Determine if the charging inverter device sends a signal to close the lithium battery pack switch. If yes, proceed to the next step; otherwise, repeat the grid connection command twice more. If all three startups fail, trigger an alarm.

[0025] Wait for a preset time to determine if the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue waiting until the power distribution is stable.

[0026] The first lithium battery pack successfully connected to the grid;

[0027] Repeat the above steps to continue starting the subsequent lithium battery pack.

[0028] Optionally, wait a preset time to determine if the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue waiting until the power distribution is stable, including:

[0029] Determine if there are other lithium battery packs or generator units already on the grid. If so, proceed to the next step; otherwise, skip the steps of adjusting the charging inverter and determining whether the three requirements for grid connection are met, and directly proceed to the step of sending the lithium battery pack switch closing signal.

[0030] Adjust the voltage, frequency, and phase of the charging inverter output according to the ship's power grid information;

[0031] Wait for the preset time to determine if the three requirements for grid connection are met. If so, proceed to the next step; otherwise, continue adjusting until the requirements are met.

[0032] The control unit sends a lithium battery pack switch-on signal to the power management system.

[0033] After confirming that the lithium battery pack switch is closed, power distribution is performed according to the droop control method.

[0034] Optionally, the control method for starting and charging the lithium battery pack specifically includes:

[0035] Confirm that the shaft-driven motor power output mode is on-grid or shore power on-grid, that the power switch of each lithium battery pack is in the open state, and that each charging inverter is ready.

[0036] Receive the available charging power signal sent by the power management system and calculate the available charging power of a single lithium battery pack;

[0037] If all lithium battery pack start-up charging commands are received and the start-up charging conditions are met, then control the first lithium battery pack to start charging.

[0038] Determine if the first lithium battery pack has started charging successfully. If successful, send a signal indicating successful operation of the first lithium battery pack and continue with the steps to start the subsequent lithium battery packs; otherwise, send a signal indicating failure to start the first lithium battery pack.

[0039] After each lithium battery pack is started in sequence, the numbers of the lithium battery packs that were successfully charged and the numbers of the lithium battery packs that failed to charge are reported.

[0040] Based on the start-up status of the lithium battery pack, the available charging power of a single lithium battery pack is recalculated, and the updated available charging power command for a single lithium battery pack is sent to each charging inverter.

[0041] The lithium battery pack that has successfully started can be charged according to the updated available charging power for a single lithium battery pack.

[0042] Optionally, it is determined whether the first lithium battery pack has successfully started charging. If successful, a signal indicating successful operation of the first lithium battery pack is sent, and the steps to start the subsequent lithium battery packs are continued; otherwise, a signal indicating failure to start the first lithium battery pack is sent, including:

[0043] Send charging mode commands to the charging inverter;

[0044] Determine if the charging inverter device is feeding back a charging mode signal. If yes, proceed to the next step; otherwise, feed back a charging start failure signal and trigger an alarm.

[0045] Send a single lithium battery pack's available charging power command to the charging inverter;

[0046] Send a start command to the charging inverter;

[0047] Determine if the charging inverter has started running. If it has, proceed to the next step; otherwise, repeat the start command twice more. If all three start attempts fail, an alarm will be triggered.

[0048] Determine if the charging inverter device has fed back a lithium battery pack switch closing signal. If yes, proceed to the next step; otherwise, continue waiting for the lithium battery pack switch closing signal.

[0049] Wait for a preset time to determine if the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue waiting until the power distribution is stable.

[0050] The first lithium battery pack has successfully started charging.

[0051] Repeat the above steps to continue starting the subsequent lithium battery pack.

[0052] Optionally, the control method for disconnecting lithium battery packs specifically includes:

[0053] If a command to disconnect all lithium battery packs is received, then the first lithium battery pack is disconnected.

[0054] Determine if the first lithium battery pack has been successfully disconnected. If so, turn off the grid connection indicator light for the first lithium battery pack and continue with the disconnection process for subsequent lithium battery packs; otherwise, continue waiting.

[0055] After sequentially disconnecting each lithium battery pack, feedback is sent indicating that the disconnection of all lithium battery packs is complete.

[0056] Optionally, determine whether the first lithium battery pack has been successfully disconnected. If so, turn off the grid connection indicator light for the first lithium battery pack and continue executing the disconnection steps for subsequent lithium battery packs; otherwise, continue waiting, including:

[0057] Determine if the charging inverter device sends a signal indicating that the battery pack switch has tripped. If yes, proceed to the next step; otherwise, continue waiting.

[0058] Wait for a preset time, then send a shutdown command to the charging inverter.

[0059] Determine if the power distribution has stabilized. If so, proceed to the next step; otherwise, continue waiting.

[0060] The first lithium battery pack was successfully disconnected.

[0061] Repeat the above steps to continue decoupling subsequent lithium battery packs.

[0062] Optionally, determine whether the charging inverter device has fed back a battery pack switch trip signal. If yes, proceed to the next step; otherwise, continue waiting, including:

[0063] Determine the mode of the charging inverter;

[0064] If the charging inverter is in discharge mode, determine whether there are other generator sets on the grid. If so, proceed to the next step; otherwise, proceed to the step of determining whether the disconnection conditions are met.

[0065] The control unit for charging inverters transfers the load to the grid-connected units, and then proceeds to the step of determining whether the disconnection conditions are met.

[0066] If the charging inverter is in charging mode, control the charging inverter to reduce the charging power of the lithium battery pack to zero;

[0067] Determine if the unblocking condition is met. If yes, proceed to the next step; otherwise, continue waiting.

[0068] The control unit sends a lithium battery pack switch trip signal to the power management system.

[0069] Optionally, after waiting for a preset time and then sending a shutdown command to the charging inverter, the process also includes:

[0070] The control charging inverter will stop after receiving a shutdown command.

[0071] According to another aspect of the present invention, a marine hybrid power system is provided, characterized in that it includes multiple lithium battery packs, multiple diesel generator sets, charging inverters corresponding to each lithium battery pack, AC shore power boxes, shaft-driven motors, a marine electrical grid, and a controller; the controller is used to execute the control method of the marine hybrid power system in any embodiment.

[0072] The technical solution of this invention controls the starting, grid connection, charging, discharging, and shutdown / disconnection of multiple lithium battery packs according to the start-up and grid connection commands, the start-up and charging commands, and the disconnection commands. Specifically, it executes the control methods for starting, grid connection, and discharging of lithium battery packs, the control methods for starting, charging, and disconnecting lithium battery packs, respectively. This enables the hybrid power ship to start and connect multiple lithium battery packs to the grid and discharge to the AC power grid, charge multiple lithium battery packs from the AC power grid, and shut down and disconnect multiple lithium battery packs.

[0073] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0074] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0075] Figure 1 A flowchart of a control method for a marine hybrid power system provided in an embodiment of the present invention;

[0076] Figure 2 A flowchart of a control method for starting and discharging a lithium battery pack according to an embodiment of the present invention;

[0077] Figure 3 A flowchart of another control method for starting and discharging a lithium battery pack according to an embodiment of the present invention;

[0078] Figure 4 A flowchart illustrating another control method for starting and discharging a lithium battery pack according to an embodiment of the present invention;

[0079] Figure 5 A flowchart of a control method for starting and charging a lithium battery pack provided in an embodiment of the present invention;

[0080] Figure 6 A flowchart of another control method for starting and charging a lithium battery pack provided in an embodiment of the present invention;

[0081] Figure 7 A flowchart of a control method for disconnecting lithium battery packs provided in an embodiment of the present invention;

[0082] Figure 8A flowchart illustrating another control method for decoupling lithium battery packs provided in an embodiment of the present invention;

[0083] Figure 9 A flowchart illustrating another control method for splitting a lithium battery pack, provided in an embodiment of the present invention;

[0084] Figure 10 This is a schematic diagram of a marine hybrid power system provided in an embodiment of the present invention. Detailed Implementation

[0085] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0086] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0087] This invention provides a control method for a marine hybrid power system, which can be executed by the marine hybrid power system. Figure 1 A flowchart of a control method for a marine hybrid power system provided in an embodiment of the present invention is shown below. Figure 1 As shown, the control method includes:

[0088] S101, Receive the operation instructions sent by the user; the operation instructions include: all lithium battery pack start-up and grid connection instructions, all lithium battery pack start-up and charging instructions, and all lithium battery pack disconnection instructions.

[0089] Specifically, all lithium battery pack start-up and grid-connection commands instruct the lithium battery packs to perform start-up, grid-connection, and discharge operations. All lithium battery pack start-up and charging commands instruct the lithium battery packs to perform start-up and charging operations. All lithium battery pack disconnection commands instruct the lithium battery packs to perform shutdown and disconnection operations. The marine hybrid power system receives operating commands from the user and executes corresponding operations based on these commands.

[0090] S102. Control method for starting and discharging lithium battery packs according to all lithium battery pack start-up and grid-connection commands.

[0091] Specifically, the control method for starting and discharging lithium battery packs according to all lithium battery pack start-up and grid connection commands controls the starting, grid connection, and discharge of multiple lithium battery packs to the ship's power grid to supply power to the ship.

[0092] S103. A control method for executing lithium battery pack start-up charging based on all lithium battery pack start-up charging commands.

[0093] Specifically, a control method for starting and charging lithium battery packs is implemented based on all lithium battery pack start-up and charging commands, and multiple lithium battery packs are charged through the ship's electrical grid.

[0094] S104. Control method for executing the de-listing of lithium battery packs according to the command to de-list all lithium battery packs.

[0095] Specifically, the control method for disconnecting lithium battery packs is executed according to the command to disconnect all lithium battery packs; wherein, disconnecting lithium battery packs means disconnecting the lithium battery packs from the ship's electrical grid, so that the lithium battery packs are not under load.

[0096] The technical solution of this embodiment controls the starting, grid connection, charging, discharging, and shutdown / disconnection of multiple lithium battery packs according to the start-up and grid connection commands, the start-up and charging commands, and the disconnection commands. That is, it executes the control methods for starting, grid connection, and discharging of lithium battery packs, the control methods for starting, charging, and disconnecting lithium battery packs, respectively, thereby realizing the functions of starting and connecting multiple lithium battery packs to the grid and discharging them into the AC grid, charging multiple lithium battery packs from the AC grid, and shutting down and disconnecting multiple lithium battery packs in hybrid power ships.

[0097] Based on the above embodiments, optionally, Figure 2 A flowchart of a control method for starting and discharging a lithium battery pack according to an embodiment of the present invention is provided, see [link to flowchart]. Figure 2 The control method includes:

[0098] S201. Confirm that the power switch of each lithium battery pack is in the open state, each charging inverter is ready, and the shore power switch is not running.

[0099] Specifically, the open state means the switch is off. The charging inverter being ready means the charging inverter is fault-free and in standby mode. The shore power switch not operating means the vessel is not connected to shore power; shore power refers to a mode of drawing power from the land power grid, where vessels docked in port shut down their auxiliary generators and instead use clean energy provided by the port to power their main onboard systems. Confirm that the power switches for each lithium battery pack in the hybrid power system are open, each charging inverter is ready, and the shore power switch is not operating.

[0100] S202. If all lithium battery pack start-up and grid connection commands are received and the start-up and grid connection conditions are met, then control the first lithium battery pack to start up and connect to the grid.

[0101] Specifically, the start-up and grid connection conditions include the power switch of each lithium battery pack being in the open state, each charging inverter being ready, and the shore power switch not being in operation. If start-up and grid connection commands for all lithium battery packs are received and the start-up and grid connection conditions are met, then a start-up and grid connection command for the first lithium battery pack is issued to control the start-up and grid connection of the first lithium battery pack, that is, to control the start-up of the first lithium battery pack and its connection to the ship's power grid.

[0102] S203. Determine whether the first lithium battery pack has been successfully connected to the grid. If successful, send a signal indicating that the first lithium battery pack has started successfully and continue to execute the steps to start the subsequent lithium battery packs; otherwise, send a signal indicating that the first lithium battery pack has failed to start.

[0103] Specifically, it determines whether the first lithium battery pack has been successfully connected to the grid. If successful, it sends a signal indicating that the first lithium battery pack has started successfully; otherwise, it sends a signal indicating that the first lithium battery pack has failed to start and continues to execute the steps to start the subsequent lithium battery packs. The steps to continue to start the subsequent lithium battery packs include changing the lithium battery pack number, continuing to send the lithium battery pack start-up and grid connection command, and controlling the remaining lithium battery packs to start up and connect to the grid.

[0104] S204. After starting each group of lithium battery packs in sequence, determine whether at least one group of lithium battery packs is running. If so, return the number of the grid-connected lithium battery pack; otherwise, return a lithium battery system start-up failure signal.

[0105] Specifically, after each lithium battery pack is started in sequence, it is determined whether at least one lithium battery pack is running. If so, the grid-connected lithium battery pack number is fed back; otherwise, it indicates that multiple lithium battery packs have failed to start and connect to the grid, and cannot supply power to the ship, so a lithium battery system start-up failure signal is fed back.

[0106] S205, The lithium battery pack that has been successfully started controls the power supply to the ship.

[0107] Specifically, the system controls the successfully started lithium battery packs to supply power to the ship based on the feedback of the successfully connected lithium battery pack numbers.

[0108] The technical solution of this embodiment, through a control method that executes the starting, grid connection, and discharge of lithium battery packs according to the starting and grid connection commands of all lithium battery packs, controls multiple lithium battery packs to perform starting, grid connection, and discharge operations respectively, thereby realizing the function of starting and connecting multiple lithium battery packs of hybrid power ships to the AC power grid; by controlling the lithium battery packs according to their number sequence and providing feedback on the numbers of lithium battery packs that have successfully or failed to perform the operation, it is easier to understand or control the specific lithium battery pack status more intuitively.

[0109] Optionally, Figure 3 A flowchart of another control method for starting and discharging a lithium battery pack according to an embodiment of the present invention is provided. See also Figure 3 The control method includes:

[0110] S301. Confirm that the power switch of each lithium battery pack is in the open state, each charging inverter is ready, and the shore power switch is not running.

[0111] S302. If all lithium battery pack start-up and grid connection commands are received and the start-up and grid connection conditions are met, then control the first lithium battery pack to start up and connect to the grid.

[0112] S303. Determine whether the State of Charge (SOC) of the first lithium battery pack is greater than the preset SOC. If yes, proceed to the next step; otherwise, report a signal that the first lithium battery pack has insufficient power and fails to start and connect to the grid.

[0113] Specifically, the state of charge (SOC) of the lithium battery pack reflects the remaining charge of the lithium battery pack. The preset SOC can be set as needed; for example, it can be set to 30%. When the SOC of the lithium battery pack is lower than the preset SOC, it indicates that the remaining charge of the lithium battery pack is insufficient and cannot supply power to the ship. The system checks whether the SOC of the first lithium battery pack is greater than the preset SOC. If it is, it proceeds to the next step; otherwise, it sends a signal indicating that the first lithium battery pack has insufficient charge and the grid connection has failed.

[0114] S304, Send a signal that other lithium battery packs / units are on the grid to the charging inverter.

[0115] Specifically, the unit may include a diesel generator set. A signal indicating that other lithium battery packs / generator sets are connected to the grid is sent to the charging inverter, meaning that in addition to the currently controlled lithium battery pack, other lithium battery packs or diesel generator sets are connected to the ship's power grid to supply power to the ship. When other lithium battery packs or generator sets are on the grid, controlling the lithium battery pack to connect to the grid requires meeting three grid connection requirements; direct connection is not allowed. These three requirements include that the voltage, frequency, and phase of the generator and the system must be consistent.

[0116] S305, Send discharge mode command to charging inverter.

[0117] Specifically, a discharge mode command is sent to the charging inverter, which then controls the lithium battery pack to discharge according to the discharge mode command, thereby supplying power to the ship.

[0118] S306. Determine whether the charging inverter device feeds back a discharge mode signal. If yes, proceed to the next step; otherwise, feed back a discharge mode switching failure and grid connection failure signal.

[0119] Specifically, it is determined whether the charging inverter device feeds back a discharge mode signal. If so, it means that the lithium battery pack can discharge normally and proceed to the next step; otherwise, it means that the lithium battery pack may be faulty and cannot discharge, and feeds back a discharge mode switching failure and grid connection failure signal.

[0120] S307. Send a start command to the charging inverter.

[0121] Specifically, a start command is sent to the charging inverter, which then starts operating upon receiving the start command.

[0122] S308. Determine whether the charging inverter has started running. If so, proceed to the next step; otherwise, repeat the start command twice more. If all three starts fail, an alarm will be triggered.

[0123] Specifically, determine whether the charging inverter has started running. If it has, proceed to the next step; otherwise, repeat the start command twice more. If all three start commands fail, it indicates that the charging inverter has malfunctioned, and an alarm will be triggered to alert the user.

[0124] S309. Send grid connection command to the charging inverter.

[0125] Specifically, a grid connection command is sent to the charging inverter, which then controls the lithium battery pack to connect to the grid.

[0126] S310. Determine whether the charging inverter device has fed back a lithium battery pack switch closing signal. If yes, proceed to the next step; otherwise, repeat the grid connection command twice more. If all three startups fail, an alarm will be triggered.

[0127] Specifically, it determines whether the charging inverter device has fed back a signal indicating that the lithium battery pack switch is closed. If so, it means that the lithium battery pack switch is closed and the ship's power grid has been connected, and proceeds to the next step; otherwise, it repeats the grid connection command twice more. If all three starts fail, it means that the lithium battery pack has malfunctioned, and an alarm is triggered to notify the user.

[0128] S311. Wait for a preset time to determine if the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue to wait until the power distribution is stable.

[0129] Specifically, the preset time can be set as needed; for example, it can be 3 seconds. The preset waiting time is used to wait for the system power distribution to stabilize. The system determines whether the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue waiting until the power distribution stabilizes. Specifically, when the voltage fluctuation is <5%, it can be confirmed that the power distribution of the charging inverter is stable. Unstable power distribution can easily affect the operating efficiency of generators, etc., and may even cause malfunctions.

[0130] S312, Feedback signal indicating successful grid connection of the first lithium battery pack.

[0131] Specifically, once the power distribution of the charging inverter is stable, it indicates that the first lithium battery pack has successfully started and connected to the grid, and a signal indicating successful grid connection of the first lithium battery pack is sent back.

[0132] S313. Repeat the above steps to continue starting the subsequent lithium battery pack.

[0133] Specifically, repeat the above steps, change the lithium battery pack number, and continue to control the remaining lithium battery pack to start and connect to the grid.

[0134] S314. After starting each group of lithium battery packs in sequence, determine whether at least one group of lithium battery packs is running. If so, return the number of the grid-connected lithium battery pack; otherwise, return a lithium battery system start-up failure signal.

[0135] S315, The lithium battery pack that has been successfully started controls the power supply to the ship.

[0136] Optionally, Figure 4 A flowchart of another control method for starting and discharging a lithium battery pack according to an embodiment of the present invention is provided, see [link to flowchart]. Figure 4 The control method includes:

[0137] S401. Confirm that the power switch of each lithium battery pack is in the open state, each charging inverter is ready, and the shore power switch is not in operation.

[0138] S402. If all lithium battery pack start-up and grid connection commands are received and the start-up and grid connection conditions are met, then control the first lithium battery pack to start up and connect to the grid.

[0139] S403. Determine whether the State of Charge (SOC) of the first lithium battery pack is greater than the preset SOC. If yes, proceed to the next step; otherwise, report a signal that the first lithium battery pack has insufficient power and the grid connection has failed.

[0140] S404, Send a signal that other lithium battery packs / units are on the grid to the charging inverter.

[0141] S405, Send discharge mode command to charging inverter.

[0142] S406. Determine whether the charging inverter device feeds back a discharge mode signal. If yes, proceed to the next step; otherwise, feed back a discharge mode switching failure and grid connection failure signal.

[0143] S407. Send a start command to the charging inverter.

[0144] S408. Determine if the charging inverter has started running. If so, proceed to the next step; otherwise, repeat the start command twice more. If all three start commands fail, an alarm will be triggered.

[0145] S409. Send grid connection command to the charging inverter.

[0146] S410. Determine whether the charging inverter device has fed back a lithium battery pack switch closing signal. If yes, proceed to the next step; otherwise, repeat the grid connection command twice more. If all three startups fail, an alarm will be triggered.

[0147] S411. Determine if there are other lithium battery packs or generator units already on the grid. If so, proceed to the next step; otherwise, skip the steps of adjusting the charging inverter and determining whether the three requirements for grid connection are met, and directly proceed to the step of sending the lithium battery pack switch closing signal.

[0148] Specifically, it determines whether other lithium battery packs or generator units are already on the grid. If so, when other lithium battery packs or generator units are on the grid, the control of the lithium battery pack grid connection must meet the three elements of grid connection, and it cannot be directly closed. Otherwise, it directly enters the step of sending the lithium battery pack switch closing signal to control the lithium battery pack switch to close.

[0149] S412. Adjust the voltage, frequency and phase of the charging inverter output according to the ship's power grid information.

[0150] Specifically, based on the ship's electrical grid information, namely the system's voltage, frequency, and phase, the voltage, frequency, and phase output of the charging inverter are adjusted.

[0151] S413. Wait for the preset time to determine whether the three requirements for grid connection are met. If yes, proceed to the next step; otherwise, continue adjusting until the requirements are met.

[0152] Specifically, the preset time can be set as needed; for example, it can be 3 seconds. The preset waiting time is used to wait for the voltage, frequency, and phase output of the charging inverter to stabilize. After waiting for the preset time, it is determined whether the three requirements for grid connection are met. If so, proceed to the next step; otherwise, continue adjusting until the requirements are met.

[0153] S414: Control the charging inverter to send the lithium battery pack switch closing signal to the power management system.

[0154] Specifically, the power management system can be used to control power distribution, battery pack switching on / off, load power limiting, etc. The control inverter sends a lithium battery pack switching on / off signal to the power management system, which then controls the lithium battery pack switching on / off.

[0155] S415. After confirming that the lithium battery pack switch is closed, power distribution is performed according to the droop control method.

[0156] Specifically, the droop control method involves selecting a frequency similar to that of a traditional generator to obtain stable frequency and voltage, ensuring power balance and frequency uniformity within the power grid. After confirming the lithium battery pack switch is closed, power distribution to the lithium battery pack is performed according to the droop control method.

[0157] S416, Feedback signal indicating successful grid connection of the first lithium battery pack.

[0158] S417. Repeat the above steps to continue starting the subsequent lithium battery pack.

[0159] S418. After starting each lithium battery pack in sequence, determine whether at least one lithium battery pack is running. If so, return the grid-connected lithium battery pack number; otherwise, return a lithium battery system start-up failure signal.

[0160] S419, The lithium battery pack that has been successfully started provides power to the ship.

[0161] Optionally, Figure 5 A flowchart of a control method for starting and charging a lithium battery pack, provided in an embodiment of the present invention, is shown below. Figure 5 The control method includes:

[0162] S501. Confirm that the shaft-driven motor power output mode is on-grid or shore power on-grid, that the power switch of each lithium battery pack is in the open state, and that each charging inverter is ready.

[0163] Specifically, the shaft-driven motor power take-out (PTO) mode refers to the mode in which the shaft-driven generator operates as a generator. Shore power in-grid refers to shore power being connected to the ship's power grid, i.e., supplying power to the main shipboard systems via clean energy provided by the port. Confirm that the shaft-driven motor power take-out mode or shore power in-grid is active in the hybrid power system, that the power switches for each lithium battery pack are in the open position, and that each charging inverter is ready.

[0164] S502: Receive the available charging power signal sent by the power management system and calculate the available charging power of a single lithium battery pack.

[0165] Specifically, it receives the available charging power signal sent by the power management system and calculates the available charging power of a single lithium battery pack. The available charging power of a single lithium battery pack is calculated as: Available charging power / Total number of lithium battery packs.

[0166] S503: If all lithium battery pack start-up charging commands are received and the start-up charging conditions are met, then control the first lithium battery pack to start charging.

[0167] Specifically, the starting charging conditions include the shaft-driven motor power output mode being on the grid or shore power being on the grid, the power switch of each lithium battery pack being in the open state, and each charging inverter being ready. If all lithium battery pack starting charging commands are received and the starting charging conditions are met, a starting charging command for the first lithium battery pack is issued to control the starting charging of the first lithium battery pack, that is, to control the starting of the first lithium battery pack and connect it to the ship's power grid, so that the first lithium battery pack is charged through the ship's power grid.

[0168] S504. Determine whether the first lithium battery pack has started charging successfully. If successful, send a signal indicating that the first lithium battery pack has started charging successfully and continue to execute the steps to start the subsequent lithium battery packs; otherwise, send a signal indicating that the first lithium battery pack has failed to start charging.

[0169] Specifically, it determines whether the first lithium battery pack has successfully started charging. If successful, it sends a signal indicating that the first lithium battery pack has started charging successfully; otherwise, it sends a signal indicating that the first lithium battery pack has started charging successfully and continues to execute the steps to start the subsequent lithium battery packs. The steps to continue to start the subsequent lithium battery packs include changing the lithium battery pack number, continuing to send lithium battery pack start charging commands, and controlling the remaining lithium battery packs to start charging.

[0170] S505: After starting each lithium battery pack in sequence, the system will report the numbers of the lithium battery packs that were successfully charged and those that failed to charge.

[0171] Specifically, after each lithium battery pack is started in sequence, the system returns the numbers of the lithium battery packs that were successfully charged and those that failed to charge, based on the start-up status.

[0172] S506. Recalculate the available charging power of a single lithium battery pack based on the starting status of the lithium battery pack, and send the updated available charging power command of the single lithium battery pack to each charging inverter.

[0173] Specifically, the available charging power of a single lithium battery pack is recalculated based on the startup status of the lithium battery pack, and the updated available charging power command for a single lithium battery pack is sent to each charging inverter. Here, the available charging power for a single lithium battery pack at this time = available charging power / number of lithium battery packs successfully charged.

[0174] S507: The lithium battery pack that has been successfully started is charged according to the updated available charging power of the single lithium battery pack.

[0175] The technical solution of this embodiment, through a control method that executes lithium battery pack start-up and charging commands according to all lithium battery pack start-up and charging commands, controls multiple lithium battery packs to perform start-up and charging operations respectively, thereby realizing the function of charging multiple lithium battery packs from the AC power grid of a hybrid-powered ship. By controlling the lithium battery packs according to their numerical order and providing feedback on the numbers of lithium battery packs that succeeded or failed in their operations, it is easier to understand or control the status of specific lithium battery packs more intuitively. In addition, by recalculating the available charging power of a single lithium battery pack based on the number of successfully charged lithium battery packs, the full utilization of grid power is achieved, improving the charging efficiency of the lithium battery packs.

[0176] Optionally, Figure 6 A flowchart of another control method for starting and charging a lithium battery pack provided in an embodiment of the present invention is shown below. Figure 6 The control method includes:

[0177] S601. Confirm that the shaft-driven motor power output mode is on-grid or shore power on-grid, that the power switch of each lithium battery pack is in the open state, and that each charging inverter is ready.

[0178] S602: Receive the available charging power signal sent by the power management system and calculate the available charging power of a single lithium battery pack.

[0179] S603. If all lithium battery pack start-up charging commands are received and the start-up charging conditions are met, then control the first lithium battery pack to start charging.

[0180] S604. Send charging mode command to the charging inverter.

[0181] Specifically, a charging mode command is sent to the charging inverter, which then controls the lithium battery pack to begin charging.

[0182] S605. Determine whether the charging inverter device is feeding back a charging mode signal. If yes, proceed to the next step; otherwise, feed back a charging start failure signal and trigger an alarm.

[0183] Specifically, it determines whether the charging inverter device feeds back a charging mode signal. If it does, it means that the lithium battery pack can be charged normally, and proceeds to the next step; otherwise, it means that the lithium battery pack may be faulty and cannot be charged, and a start-up charging failure signal is fed back and an alarm is triggered.

[0184] S606: Send a command for the available charging power of a single lithium battery pack to the charging inverter.

[0185] Specifically, a command for the available charging power of a single lithium battery pack is sent to the charging inverter, which then controls the lithium battery packs to charge according to the available charging power of that single lithium battery pack. Here, the available charging power of a single lithium battery pack is calculated as: available charging power / total number of lithium battery packs.

[0186] S607, Send a start command to the charging inverter.

[0187] Specifically, a start command is sent to the charging inverter, which then starts operating upon receiving the start command.

[0188] S608. Determine whether the charging inverter has started running. If so, proceed to the next step; otherwise, repeat the start command twice more. If all three starts fail, an alarm will be triggered.

[0189] Specifically, determine whether the charging inverter has started running. If it has, proceed to the next step; otherwise, repeat the start command twice more. If all three start commands fail, it indicates that the charging inverter has malfunctioned, and an alarm will be triggered to alert the user.

[0190] S609. Determine whether the charging inverter device has fed back a lithium battery pack switch closing signal. If yes, proceed to the next step; otherwise, continue to wait for the lithium battery pack switch closing signal.

[0191] Specifically, it determines whether the charging inverter device has fed back a signal indicating that the lithium battery pack switch is closed. If so, it means that the lithium battery pack switch is closed and the ship's power grid has been connected, and proceeds to the next step; otherwise, it repeats the grid connection command twice more. If all three starts fail, it means that the lithium battery pack has malfunctioned, and an alarm is triggered to notify the user.

[0192] S610. Wait for a preset time to determine if the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue to wait until the power distribution is stable.

[0193] Specifically, the preset time can be set as needed; for example, it can be 3 seconds. The preset waiting time is used to wait for the system power distribution to stabilize. The system determines whether the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue waiting until the power distribution stabilizes. Specifically, when the voltage fluctuation is <5%, it can be confirmed that the power distribution of the charging inverter is stable. Unstable power distribution can easily affect the operating efficiency of generators, etc., and may even cause malfunctions.

[0194] S611, Feedback signal indicating successful start-up and charging of the first lithium battery pack.

[0195] Specifically, once the power distribution of the charging inverter is stable, it indicates that the first lithium battery pack has successfully started charging, and a signal indicating that the first lithium battery pack has successfully started charging is sent back.

[0196] S612. Repeat the above steps to continue starting the subsequent lithium battery pack.

[0197] Specifically, repeat the above steps, change the lithium battery pack number, and continue to control the remaining lithium battery pack to start charging.

[0198] S613. After starting each lithium battery pack in sequence, the numbers of the lithium battery packs that were successfully charged and the numbers of the lithium battery packs that failed to charge are reported back.

[0199] S614. Recalculate the available charging power of a single lithium battery pack based on the starting status of the lithium battery pack, and send the updated available charging power command of a single lithium battery pack to each charging inverter.

[0200] S615, Control the successfully started lithium battery pack to charge according to the updated available charging power of the single lithium battery pack.

[0201] Optionally, Figure 7 A flowchart of a control method for disconnecting lithium battery packs provided in an embodiment of the present invention is shown below. Figure 7 The control method includes:

[0202] S701. If a command to disconnect all lithium battery packs is received, control the disconnection of the first lithium battery pack.

[0203] Specifically, if a command to disconnect all lithium battery packs is received, a command to disconnect the first lithium battery pack is issued to control the disconnection of the first lithium battery pack, that is, to control the first lithium battery pack to start and disconnect from the ship's power grid, and stop supplying power to the ship's load.

[0204] S702. Determine whether the first lithium battery pack has been successfully disconnected. If so, turn off the grid connection indicator light of the first lithium battery pack and continue to execute the steps to disconnect the subsequent lithium battery packs; otherwise, continue to wait.

[0205] Specifically, it determines whether the first lithium battery pack has been successfully disconnected. If so, it controls the grid connection indicator light of the first lithium battery pack to turn off, indicating that the first lithium battery pack has been disconnected from the ship's power grid. Otherwise, it continues to wait for the first lithium battery pack to disconnect and continues to execute the steps to disconnect the subsequent lithium battery packs. The steps to disconnect the subsequent lithium battery packs include changing the lithium battery pack number, continuing to send lithium battery pack disconnection commands, and controlling the disconnection of the remaining lithium battery packs.

[0206] S703: After sequentially disconnecting each lithium battery pack, feedback is given that the disconnection of all lithium battery packs is complete.

[0207] Specifically, after each lithium battery pack is disconnected in sequence, a signal indicating that the disconnection of all lithium battery packs is complete is sent back, meaning that all lithium battery packs have been disconnected from the ship's power grid and have stopped supplying power to the ship's loads.

[0208] The technical solution of this embodiment uses a control method that executes the decoupling of lithium battery packs according to the command to decouple all lithium battery packs, thereby controlling multiple lithium battery packs to perform shutdown and decoupling operations respectively, and thus realizing the function of decoupling multiple lithium battery packs in hybrid ships.

[0209] Optionally, Figure 8 A flowchart of another control method for decoupling lithium battery packs provided in an embodiment of the present invention is available. Figure 8 The control method includes:

[0210] S801. If a command to disconnect all lithium battery packs is received, control the disconnection of the first lithium battery pack.

[0211] S802. Determine whether the charging inverter device has fed back a battery pack switch trip signal. If yes, proceed to the next step; otherwise, continue waiting.

[0212] Specifically, determine whether the charging inverter device has fed back a signal indicating that the lithium battery pack switch has tripped. If so, it means that the lithium battery pack switch has tripped and has been disconnected from the ship's power grid, and proceed to the next step; otherwise, continue to wait for the lithium battery pack switch to trip.

[0213] S803, wait for the preset time, and then send a shutdown command to the charging inverter.

[0214] Specifically, the preset time can be set as needed; for example, it can be 3 seconds. The waiting preset time is used to wait for the system to stabilize. After waiting for the preset time, a shutdown command is sent to the charging inverter to control the charging inverter to shut down.

[0215] S804. Determine if the power distribution has reached a stable state. If so, proceed to the next step; otherwise, continue waiting.

[0216] Specifically, determine whether the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue waiting until the power distribution stabilizes. When the voltage fluctuation is less than ±5%, the power distribution of the charging inverter can be considered stable. Unstable power distribution can easily affect the operating efficiency of generators and other components, and may even cause malfunctions.

[0217] S805, feedback signal indicating successful disconnection of the first lithium battery pack.

[0218] Specifically, once the power distribution of the charging inverter is stable, it indicates that the first lithium battery pack has been successfully disconnected, and a signal indicating successful disconnection of the first lithium battery pack is sent back.

[0219] S806. Repeat the above steps to continue decoupling subsequent lithium battery packs.

[0220] Specifically, repeat the above steps, change the lithium battery pack number, and continue to control the disconnection of the remaining lithium battery packs.

[0221] S807: After sequentially disconnecting each lithium battery pack, feedback is given that the disconnection of all lithium battery packs is complete.

[0222] Optionally, Figure 9 A flowchart of another control method for splitting a lithium battery pack provided in an embodiment of the present invention is shown below. Figure 9 The control method includes:

[0223] S901. If an instruction to disconnect all lithium battery packs is received, control the disconnection of the first lithium battery pack.

[0224] S902. Determine the mode of the charging inverter.

[0225] Specifically, determine the mode of the charging inverter; the mode of the charging inverter includes discharging mode and charging mode.

[0226] S903. If the charging inverter is in discharge mode, determine whether there are other generator sets on the grid. If so, proceed to the next step; otherwise, proceed to the step of determining whether the disconnection conditions are met.

[0227] Specifically, if the charging inverter is in discharge mode, it means that the lithium battery pack is supplying power to the ship's load and cannot be directly disconnected. The load needs to be transferred or the output power reduced to stop supplying power to the ship. It is then necessary to determine whether there are other generator sets on the grid. If so, proceed to the next step; otherwise, proceed to the step of determining whether the disconnection conditions are met.

[0228] S904, Control the charging inverter to transfer the load to the grid-connected unit, and proceed to the step of determining whether the disconnection conditions are met.

[0229] Specifically, when other generator sets are on the grid, the control charging inverter transfers the load of the lithium battery pack to the on-grid generator set, and then proceeds to the step of determining whether the lithium battery pack meets the disconnection conditions.

[0230] S905. If the charging inverter is in charging mode, control the charging inverter to reduce the charging power of the lithium battery pack to zero.

[0231] Specifically, if the charging inverter is in charging mode, it means that the lithium battery pack is being charged by the ship's load and cannot be directly disconnected. The charging inverter needs to be controlled to reduce the charging power of the lithium battery pack to zero.

[0232] S906. Determine if the unblocking condition is met. If yes, proceed to the next step; otherwise, continue waiting.

[0233] Specifically, it determines whether the disconnection conditions are met. If so, proceed to the next step; otherwise, continue waiting for the charging inverter to transfer the load to the grid-connected unit or for the charging inverter to reduce the lithium battery pack charging power to zero. The disconnection conditions may include charging inverter output power < 5% or charging inverter output power < 25kW, and voltage fluctuation < ±5%.

[0234] S907 controls the charging inverter to send a lithium battery pack switch trip signal to the power management system.

[0235] Specifically, the control charging inverter sends a lithium battery pack switch-off signal to the power management system, which then controls the lithium battery pack switch-off to disconnect from the ship's power grid.

[0236] S908: Wait for a preset time, then send a shutdown command to the charging inverter.

[0237] S909: The control charging inverter stops after receiving a stop command.

[0238] Specifically, the control unit stops operating and shuts down after receiving a shutdown command.

[0239] S910. Determine if the power distribution has reached a stable state. If so, proceed to the next step; otherwise, continue waiting.

[0240] S911, feedback signal indicating successful disconnection of the first lithium battery pack.

[0241] S912. Repeat the above steps to continue decoupling subsequent lithium battery packs.

[0242] S913. After sequentially disconnecting each lithium battery pack, feedback is given that the disconnection of all lithium battery packs is complete.

[0243] This invention also provides a marine hybrid power system. Figure 10 This is a schematic diagram of a marine hybrid power system provided in an embodiment of the present invention. See also... Figure 10 The system includes: multiple lithium battery packs 1, multiple diesel generator sets 2, charging inverters 3 corresponding to each lithium battery pack, AC shore power boxes 4, shaft-driven motors 5, a shipboard electrical grid, and a controller; the controller is used to execute the control method of the marine hybrid power system described in any embodiment of the present invention.

[0244] Specifically, the lithium battery pack 1 and diesel generator set 2 are used as power sources to supply power to the ship's loads; the charging inverter 3 is used to convert the DC power from the lithium battery pack 1 into AC power required by the ship's power grid 6, and to realize the charging and discharging control and load distribution functions of the lithium battery pack 1. The AC shore power box 4 is used to connect to shore power to supply power to the ship; the shaft motor 5 can act as a generator to supply power to the ship. Exemplarily, the marine hybrid power system also includes an isolation transformer 7 and a shaft motor frequency converter 8 corresponding to the lithium battery pack 1. The isolation transformer 7 is used to isolate the DC power grid and the AC power grid, providing safety protection and voltage boosting; the shaft motor frequency converter 8 is used to regulate voltage, frequency, etc., to control the shaft motor 5.

[0245] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0246] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A control method for a marine hybrid power system, characterized in that, The control method includes: Receive operating instructions sent by the user; the operating instructions include: all lithium battery packs start grid connection instructions, all lithium battery packs start charging instructions, and all lithium battery packs disconnect instructions; The control method for starting and discharging lithium battery packs according to all the aforementioned start-up and grid-connection commands; A control method for starting and charging lithium battery packs according to all the lithium battery pack start-up and charging commands; The control method for executing the de-listing of lithium battery packs according to the command to de-list all lithium battery packs; The control method for disconnecting the lithium battery pack specifically includes: If a command to disconnect all lithium battery packs is received, then the first lithium battery pack is disconnected. Determine whether the first group of lithium battery packs has been successfully disconnected. If so, turn off the grid connection indicator light for the first group of lithium battery packs and continue to execute the steps to disconnect subsequent lithium battery packs; otherwise, continue to wait. After sequentially disconnecting each of the lithium battery packs, feedback is given that the disconnection of all lithium battery packs is complete; The process involves determining whether the first group of lithium battery packs has been successfully disconnected. If so, the grid connection indicator light for the first group of lithium battery packs is turned off, and the process continues to disconnect subsequent lithium battery packs; otherwise, the process continues to wait, including: Determine if the charging inverter device sends a signal indicating that the battery pack switch has tripped. If yes, proceed to the next step; otherwise, continue waiting. Wait for a preset time, and then send a shutdown command to the charging inverter. Determine if the power distribution has stabilized. If so, proceed to the next step; otherwise, continue waiting. The first lithium battery pack was successfully disconnected. Repeat the above steps to continue decoupling subsequent lithium battery packs.

2. The control method according to claim 1, characterized in that, The control method for starting and discharging the lithium battery pack specifically includes: Confirm that the power switch of each lithium battery pack is in the open state, each charging inverter is ready, and the shore power switch is not in operation. If all lithium battery pack start-up and grid connection commands are received and the start-up and grid connection conditions are met, then control the first lithium battery pack to start up and connect to the grid. Determine whether the first group of lithium battery packs has been successfully connected to the grid. If successful, send a signal indicating that the first group of lithium battery packs has started successfully and continue to execute the steps to start the subsequent lithium battery packs; otherwise, send a signal indicating that the first group of lithium battery packs has failed to start. After starting each group of lithium battery packs in sequence, determine whether at least one group of lithium battery packs is running. If so, return the grid-connected lithium battery pack number; otherwise, return a lithium battery system start-up failure signal. The lithium battery pack, once successfully started, powers the ship.

3. The control method according to claim 2, characterized in that, Determine whether the first group of lithium battery packs has been successfully connected to the grid. If successful, send a signal indicating that the first group of lithium battery packs has started successfully, and continue to execute the steps to start the subsequent lithium battery packs. Otherwise, a startup failure signal will be sent to the first lithium battery pack, including: Determine whether the State of Charge (SOC) of the first lithium battery pack is greater than the preset SOC. If so, proceed to the next step; otherwise, report a signal that the first lithium battery pack has insufficient power and the grid connection has failed. Send a signal indicating that other lithium battery packs / units are online to the charging inverter; Send a discharge mode command to the charging inverter; Determine whether the charging inverter device feeds back a discharge mode signal. If yes, proceed to the next step; otherwise, feed back a discharge mode switching failure and grid connection failure signal. Send a start command to the charging inverter; Determine whether the charging inverter has started running. If it has, proceed to the next step; otherwise, repeat the start command twice more. If all three start attempts fail, an alarm will be triggered. Send a grid connection command to the charging inverter; Determine whether the charging inverter device has fed back a lithium battery pack switch closing signal. If yes, proceed to the next step; otherwise, repeat the grid connection command twice more. If all three startups fail, an alarm will be triggered. Wait for a preset time to determine whether the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue to wait until the power distribution is stable. The first lithium battery pack successfully connected to the grid; Repeat the above steps to continue starting the subsequent lithium battery pack.

4. The control method according to claim 3, characterized in that, The preset waiting time is used to determine whether the power distribution of the charging inverter is stable. If it is, the process proceeds to the next step; otherwise, the process continues until the power distribution stabilizes, including: Determine if there are other lithium battery packs or generator units already connected to the grid. If so, proceed to the next step. Otherwise, skip the steps of adjusting the charging inverter and determining whether the three grid connection requirements are met, and directly proceed to the step of sending the lithium battery pack switch closing signal. The voltage, frequency, and phase of the charging inverter are adjusted according to the ship's electrical grid information. Wait for the preset time to determine if the three requirements for grid connection are met. If so, proceed to the next step; otherwise, continue adjusting until the requirements are met. The charging inverter is controlled to send a lithium battery pack switch-on signal to the power management system. After confirming that the lithium battery pack switch is closed, power is distributed according to the droop control method.

5. The control method according to claim 1, characterized in that, The control method for starting and charging the lithium battery pack specifically includes: Confirm that the shaft-driven motor power output mode is on-grid or shore power on-grid, that the power switch of each lithium battery pack is in the open state, and that each charging inverter is ready. Receive the available charging power signal sent by the power management system and calculate the available charging power of a single lithium battery pack; If all lithium battery pack start-up charging commands are received and the start-up charging conditions are met, then control the first lithium battery pack to start charging. Determine whether the first lithium battery pack has started charging successfully. If successful, send a signal indicating that the first lithium battery pack has started charging successfully and continue to execute the steps to start the subsequent lithium battery packs; otherwise, send a signal indicating that the first lithium battery pack has failed to start charging. After each lithium battery pack is started in sequence, the number of the lithium battery pack that was successfully charged and the number of the lithium battery pack that failed to charge are reported. Based on the start-up status of the lithium battery pack, the available charging power of a single lithium battery pack is recalculated, and the updated available charging power command for a single lithium battery pack is sent to each of the charging inverter devices. The lithium battery pack that has been successfully started can be charged according to the updated available charging power of the single lithium battery pack.

6. The control method according to claim 5, characterized in that, The process involves determining whether the first lithium battery pack has successfully started charging. If successful, a signal indicating successful operation of the first lithium battery pack is sent back, and the process continues to execute the steps for starting subsequent lithium battery packs. Otherwise, a failure signal will be sent to the first lithium battery pack, including: Send a charging mode command to the charging inverter; Determine whether the charging inverter device feeds back a charging mode signal. If yes, proceed to the next step; otherwise, feed back a charging start failure signal and trigger an alarm. Send a single charge power command for the lithium battery pack to the charging inverter; Send a start command to the charging inverter; Determine whether the charging inverter has started running. If it has, proceed to the next step; otherwise, repeat the start command twice more. If all three start attempts fail, an alarm will be triggered. Determine whether the charging inverter device has fed back a lithium battery pack switch closing signal. If yes, proceed to the next step; otherwise, continue to wait for the lithium battery pack switch closing signal. Wait for a preset time to determine whether the power distribution of the charging inverter is stable. If it is, proceed to the next step; otherwise, continue to wait until the power distribution is stable. The first lithium battery pack has successfully started charging. Repeat the above steps to continue starting the subsequent lithium battery pack.

7. The control method according to claim 1, characterized in that, The step involves determining whether the charging inverter device has fed back a battery pack switch trip signal. If yes, proceed to the next step; otherwise, continue waiting, including: Determine the mode of the charging inverter; If the charging inverter is in discharge mode, determine whether there are other generator sets on the grid. If so, proceed to the next step; otherwise, proceed to the step of determining whether the disconnection conditions are met. The charging inverter is controlled to transfer the load to the grid-connected unit, and then the step of determining whether the disconnection conditions are met is entered. If the charging inverter is in charging mode, control the charging inverter to reduce the charging power of the lithium battery pack to zero; Determine if the unblocking condition is met. If yes, proceed to the next step; otherwise, continue waiting. The charging inverter is controlled to send a lithium battery pack switch trip signal to the power management system.

8. The control method according to claim 1, characterized in that, After waiting for the preset time and then sending a shutdown command to the charging inverter, the process further includes: The charging inverter is shut down upon receiving a shutdown command.

9. A marine hybrid power system, characterized in that, It includes multiple lithium battery packs, multiple diesel generator sets, charging inverters corresponding to each of the lithium battery packs, AC shore power boxes, shaft-driven motors, marine electrical grids, and controllers; the controllers are used to execute the control method of the marine hybrid power system as described in any one of claims 1-8.

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