Power and energy management system for electric towing ship

Abstract

The invention relates to a power and energy management system for an electric towing ship. A DC1000V direct current power distribution framework is used as the basis of the system; integration and management of multiple groups of energy sources of a lithium battery, a solar panel and a shore power rectifier; an intelligent power distribution and control algorithm in different working condition modes ensures efficient, flexible and safe use of energy; a rapid fault recovery mechanism guarantees the stability and safety of the system; self-adaptive charging management is realized, intelligent charging is realized, and battery health is prevented from being damaged by overcharging. The system prolongs the service life of the battery and reduces the maintenance cost; rapid mode switching is achieved, and the response capability and safety of the ship under the emergency situation are enhanced; the system architecture is expanded, and the compatibility of a novel technology and hybrid energy is improved; the energy utilization strategy is dynamically optimized, and the overall utilization efficiency of energy is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of marine energy management, in particular to a power and energy management system for an electric tugboat. BACKGROUND

[0002] In recent years, with the development of ship electrification and intelligentization, the energy system management of electric tugboats faces technical challenges such as efficient energy distribution, multi-mode flexible control, and safe redundancy guarantee. Traditional ships have problems such as power regulation lag, low energy utilization rate, and complex manual operation, which cannot meet the needs of modern ships for energy saving and emission reduction, intelligent control, and high reliability. Firstly, the dynamic distribution of power regulation is unbalanced. Traditional systems cannot achieve dynamic power balance when multiple lithium battery groups are connected in parallel, resulting in long-term overload or underload of some battery groups, accelerating battery aging, and shortening the overall life. Secondly, mode switching is delayed and redundant. Traditional mode switching relies on manual operation, such as manually disconnecting the switch and starting the shore power rectifier when switching from navigation mode to charging mode, which is tedious and delayed, and cannot meet the rapid response needs of sudden conditions (such as emergency avoidance). Thirdly, the system architecture has limited scalability and adaptability. The existing PMS architecture is closed and cannot adapt to the access of new battery technologies or hybrid energy, limiting the future upgrade space of ships. The control logic of different working conditions (such as navigation, operation, and parking) is fixed and cannot dynamically optimize the operation strategy according to the actual ship load, resulting in low energy utilization rate. SUMMARY

[0003] To solve the above problems, a power and energy management system for an electric tugboat is proposed, which solves the bottleneck problems of traditional systems in efficiency, reliability, and safety through multi-mode dynamic control, intelligent power distribution, rapid fault recovery, and adaptive charging management, providing technical support for the efficient operation of electric ships.

[0004] The technical solution of the present application is: a power and energy management system for an electric tugboat, a DC 1000V direct current power distribution architecture as the basis of the system;

[0005] 2n groups of lithium batteries, 2m groups of solar panels, and 2 shore power rectifiers connected to the high-voltage power distribution board form multiple energy sources; 2n groups of lithium battery groups and 2m groups of solar panels are powered by one-to-one corresponding direct current power distribution board frequency converters and photovoltaic frequency converters; 2n groups of lithium battery groups can be connected to the high-voltage power distribution board for charging through 2n groups of direct current power distribution board frequency converters and 2 shore power rectifiers; 2n groups of lithium battery groups are connected in parallel and automatically load balanced between each other;

[0006] 2 sets of daily inverters and corresponding daily transformers are connected in series as a group of loads between the DC bus and the AC distribution panel, and the main propulsion motor connected to the DC bus through the main propulsion inverter is another group of loads, and the DC bus tie switch and the AC bus tie switch are connected to the middle of the DC bus and the middle of the AC distribution panel respectively to realize load sectional power supply and redundant backup;

[0007] The automatic control system includes but is not limited to the power management system, the battery management system and the daily inverter control system; the bus voltage droop control + adaptive weight distribution algorithm is used to realize power dynamic balance in different working conditions;

[0008] The safety management sampling fast fault recovery mechanism includes automatic shutdown DC / DC module, high and low voltage and power limit management of the battery management system, and automatic start of fault recovery.

[0009] Preferably, the bus voltage droop control + adaptive weight distribution algorithm is used to realize power dynamic balance, and the core formula is:

[0010] Output power Pi = P ref_batt +Kv×(Vdc-Vref)+Ks×(SOCi-SOCavg)

[0011] Wherein Pi is the output power of the i-th battery; P ref_batt is the reference power value of the lithium battery pack, which is usually obtained by dividing the total power demand minus the real-time output of solar energy according to the number of online lithium battery packs, that is, P ref_batt ≈(total demand power-total solar output) / N_online_batt, wherein N_online_batt is the number of online lithium battery packs, which represents the average power that the battery pack should share in the ideal state without voltage deviation and SOC deviation; Vdc is the DC bus voltage, SOCi is the state of charge of the i-th battery, SOCavg is the average SOC of the online battery pack, the coefficient Kv adjusts the voltage deviation weight, and the coefficient Ks adjusts the SOC balance weight;

[0012] Voltage compensation coefficient Kv: when the DC bus voltage Vdc deviates from the reference voltage value Vref, the power compensation amount is automatically adjusted;

[0013] SOC balancing coefficient Ks: dynamically adjust the output according to the real-time state of charge deviation of the battery pack, set the positive value of Ks for high SOC battery pack to improve the output, and set the negative value of Ks for low SOC group to reduce the output;

[0014] Mode switching logic:

[0015] Equal division mode: when the SOC difference between the online battery packs is less than 5%, power equalization is given priority to ensure that the output deviation of each battery pack is less than 3%.

[0016] SOC equalization mode: When the maximum difference of SOC between online battery groups is detected ≥ 5%, and lasts for 5 minutes, automatically switch to SOC equalization mode, force high SOC battery to output preferentially, and low SOC battery to reduce load to 50%, until the SOC difference between online battery groups is narrowed to below 2%.

[0017] Preferably, the implementation method of the SOC equalization mode is:

[0018] The system monitors the state of charge of all 2n groups of lithium batteries in real time, and when the difference between the highest SOC value and the lowest SOC value reaches or exceeds 5%, a preliminary determination is triggered;

[0019] Continuous duration verification: the above difference continues to exceed the limit for ≥ 5 minutes, 5 minutes is used to eliminate transient fluctuation interference, and the SOC equalization mode is formally activated;

[0020] Power dynamic allocation algorithm:

[0021] Calculate the SOC deviation rate of each group of batteries: Control rules:

[0022] High SOC battery group (ΔSOC i >0) increases output, upper limit is 110% of rated power;

[0023] Low SOC battery group (ΔSOC i <0) reduces output, lower limit is 50% of rated power;

[0024] Exit condition: the SOC difference between all online battery groups falls within 2%, automatically switch back to power equalization mode.

[0025] Preferably, the solar panel is connected to the DC bus through its dedicated photovoltaic frequency converter, and the output P_solar_j of the solar panel is independently controlled by its own maximum power point tracking.

[0026] Preferably, the battery management system has upper and lower high voltage limit management:

[0027] Upper high voltage is executed in three steps:

[0028] 1) Battery management system self-check: insulation resistance > 3MΩ, cell temperature difference < 5℃, no internal short circuit sign;

[0029] 2) Pre-charge: slowly raise the battery voltage to 80% of the DC bus voltage through a current-limiting resistor;

[0030] 3) Main contactor closed: soft start of frequency converter, complete grid connection within 10ms;

[0031] This three-step completion, the main contactor closed, representing the high voltage;

[0032] The lower high voltage conditions include:

[0033] Hard threshold: When any of the following conditions are met, the battery management system will directly perform the lower high voltage operation, disconnect the main contactor, condition 1: over-discharge prevention SOC ≤ 5%, condition 2: full charge, condition 3: thermal runaway risk temperature > 55℃;

[0034] Fault response, trigger lower high voltage: when the battery management system reports system protection shutdown, cut off the high voltage within 100ms; Mode differentiation:

[0035] Navigation mode, lower high voltage action delay <200ms, to ensure emergency maneuvering and avoid instant power failure leading to loss of control; Charging mode, the contactor is allowed to be closed only after the shore power rectifier synchronization signal is ready.

[0036] Preferably, the conditions for automatic start of fault recovery are:

[0037] 1) Lithium battery pack restart conditions:

[0038] After the fault is eliminated, the battery pack state of charge (SOC) needs to be higher than 20%, ensuring basic discharge capability;

[0039] The battery temperature must be restored to the safe working interval of 10℃-45℃;

[0040] The insulation resistance value is greater than 2MΩ, excluding the risk of electric leakage;

[0041] The cumulative restart times within 24 hours do not exceed twice, avoiding frequent actions leading to equipment damage;

[0042] 2) Solar panel restart conditions:

[0043] After the fault is eliminated and the ambient light intensity continues to be higher than 200W / m 2 for more than 5 minutes;

[0044] 3) Safety protection measures:

[0045] Within 10 minutes after the device restarts, the output power is limited to 80% of the rated value to prevent secondary fault impact; If the same device restarts again within 24 hours after the fault occurs, the system is automatically locked and triggers the "manual intervention required" alarm, disabling the self-start function.

[0046] Preferably, the system has three working modes: manual, semi-automatic, and automatic, selected through soft buttons on the touch screen. If none of the above working modes is selected, the power station is in semi-automatic mode. The automatic mode includes discharge mode and charging mode, and the discharge mode is divided into navigation mode, work mode, and parking mode.

[0047] Preferably, the navigation mode in the automatic mode:

[0048] The standby and running lithium battery group ≥ 1 group, and the solar panel ≥ 1 group can enter the navigation mode, the lithium battery group available in the mode is started according to the set starting order, when no lithium battery group and solar panel are available or other faults are detected, the mode switching is stopped and the mode switching failure alarm is popped up;

[0049] The operation mode in the automatic mode:

[0050] The standby and running lithium battery group is 2n groups, and the solar panel is 2m groups, so as to enter the operation mode, the lithium battery group available in the mode is started according to the set starting order, when no lithium battery group is available or other faults are detected, the mode switching is stopped and the mode switching failure alarm is popped up;

[0051] The mooring mode in the automatic mode:

[0052] The standby and running lithium battery group ≥ 2 groups, and the solar panel ≥ 1 group can enter the mooring mode, the two lithium battery groups with the highest power consumption are discharged in the mode, when no lithium battery group is available or other faults are detected, the mode switching is stopped and the mode switching failure alarm is popped up;

[0053] The charging mode in the automatic mode:

[0054] The mother switch is automatically tripped, the shore power rectification is automatically started, and the lithium battery group without faults is automatically started and charged; when the propulsion is running or other faults occur, the mode switching is stopped and the mode switching failure alarm is popped up.

[0055] The electric tugboat power and energy management system has the advantages that the service life of the battery is prolonged, the maintenance cost is reduced, the mode is quickly switched, the response ability and safety of the ship under the sudden condition are enhanced, the system architecture is expanded, the compatibility of the new technology and the hybrid energy is improved, the energy utilization strategy is dynamically optimized, and the overall energy utilization efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 It is a structural schematic diagram of the electric tugboat power and energy management system.

[0057] Figure 2 It is a power station management mode diagram of the electric tugboat power and energy management system. DETAILED DESCRIPTION

[0058] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0059] The power and energy management system (PMS) of this invention is based on a DC1000V DC power distribution architecture and provides different management modes through a DC power distribution board to achieve efficient and reliable energy management and control.

[0060] System topology as follows Figure 1 As shown, the system includes six 838.656kWh lithium battery packs (2, 3, 4, 5, 6, 7), two 100kWh solar panels (1, 8), six 600kW DC power distribution inverters (10, 11, 12, 15, 16, 17), two 300kW photovoltaic inverters connected to the DC busbar (9, 18), and two 900kW shore power rectifiers connected to the DC busbar (13, 14). The system supports multiple energy inputs and flexible charging and discharging. Two 1500kW main drive inverters (19, 22), two 200kW daytime inverters (20, 21), a DC bus tie switch (23), and an AC bus tie switch (24) enable segmented power supply and redundant backup for the load. The six lithium battery packs and two solar panels can be powered to the DC busbar (in discharge mode) through six DC power distribution board inverters and two photovoltaic inverters, respectively; the six lithium battery packs can be charged by connecting to the high-voltage power distribution board through six DC power distribution board inverters and two shore power rectifiers, respectively; the six lithium battery packs are connected in parallel and automatically adjust the load among themselves.

[0061] The DC switchboard offers two power station management modes: manual and PMS automatic. This can be selected via the "Local / Remote" selector switch on the DC switchboard's synchronization panel. When the switch is set to "Local," the start / stop of the inverter module and the battery voltage adjustment can be controlled locally via the panel's buttons. When the switch is set to "Remote," the PMS defaults to semi-automatic mode, allowing remote control of the DC switchboard inverter's start / stop and battery voltage adjustment via buttons on the PMS panel. When the switch is set to "Remote," different automatic mode conditions can be selected via buttons on the PMS panel, and the PMS will automatically control the start / stop of the DC switchboard inverter module and battery voltage adjustment according to the selected condition. Figure 2 As shown, there are two operating modes in PMS automatic mode: discharge mode (navigation mode, operation mode, berthing mode) and charging mode, as well as manual and semi-automatic modes. The three operating modes, manual, semi-automatic and automatic, can be selected through the soft button on the touch screen. If none of the above operating modes are selected, the power station is in semi-automatic state.

[0062] According to different working conditions in PMS automatic mode, the following working modes are divided, and the related power supply configuration and power distribution mode are described, as shown in the following Table 1.

[0063] Table 1

[0064]

[0065]

[0066] Regardless of manual, semi-automatic, automatic mode, the following functions are effective:

[0067] 1) When charging the lithium battery pack, the charging power can be set on the human-computer interaction interface (the maximum charging power available for each lithium battery pack is obtained according to the output power of the shore power rectifier, the maximum allowed charging current is calculated by the BMS (battery management system), and the minimum value of the charging power set on the human-computer interaction interface is charged);

[0068] 2) Reduce the propulsion load power, and automatically unload non-essential loads to prevent battery overload; (when the battery pack output power exceeds the rated value (0.65C, 544kW), the propulsion power is automatically limited);

[0069] 3) Automatic unloading of non-essential loads to prevent daily inverter and daily transformer overload; (when the daily inverter output exceeds the rated value for 5s, the non-essential load is automatically tripped);

[0070] 4) Automatically calculate the current power grid available power, current power grid output power, current power grid remaining power, propulsion available power, and fire water cannon available power and display on the PMS touch screen;

[0071] 5) Real-time system self-checking, system status can be viewed on the human-computer interaction interface. Complete security system is provided, and when the system fails, an alarm pop-up window is displayed on the human-computer interaction interface;

[0072] 6) Data monitoring function:

[0073] Including but not limited to the following:

[0074] (1) The charge and discharge state of each battery system;

[0075] (2) The state of charge (SOC) of each battery system;

[0076] (3) The power of charging and discharging of each battery system;

[0077] (4) The total voltage and total current of each battery system;

[0078] (5) The status of branch circuit breakers and tie switches for battery banks, solar panels, propulsion systems, and domestic load power converters;

[0079] (6) Busbar voltage of the distribution panel;

[0080] (7) Fault information of the battery system, distribution system, and other equipment;

[0081] (8) The battery system can provide real-time information on the remaining power and the time or distance that the ship can travel;

[0082] (9) The power generation status of each group of solar panels;

[0083] (10) The power, voltage, and current of each group of solar panels;

[0084] (12) The total voltage and total current of each group of solar panels.

[0085] Management mode - manual:

[0086] 1) Manually complete the BMS high-voltage setup on the local;

[0087] 2) Manually complete the DC converter charge-discharge start-stop operation on the local;

[0088] 3) Manually perform load transfer and power distribution operations on the local;

[0089] 4) Manually complete the daily inverter module start-stop operation on the local;

[0090] 5) Manually complete the shore power rectifier module start-stop operation on the local;

[0091] 6) When there is a heavy load inquiry on the local, manually determine and send an allow signal.

[0092] Management mode - semi-automatic mode:

[0093] In semi-automatic management mode, through the combination of human-computer interaction interface and automatic control, efficient management and safety protection of energy equipment are realized.

[0094] Users can perform one-key operations on specified battery banks or solar panels through the touch screen: in the discharge / charge-ready state, select the corresponding battery bank or solar panel to trigger the "one-key discharge start" or "one-key charge start" instruction, and the system will automatically complete the BMS high-voltage power-on and DC frequency converter start process; when executing "one-key shutdown", click the corresponding battery bank on the touch screen when the battery system and solar system are ready, a pop-up window of the battery bank control interface will appear, and press the "one-key shutdown" button to automatically shut down the DC frequency conversion module, automatically lower the BMS high voltage, and the remaining lithium battery bank and solar panel supply power to the power grid.

[0095] When the shore power rectifier is ready, click the corresponding shore power rectifier on the touch screen, pop up the shore power rectifier control interface pop-up window, and press the "start" button to start the shore power rectifier. When the shore power rectifier is ready, click the corresponding shore power rectifier on the touch screen, pop up the shore power rectifier control interface pop-up window, and press the "stop" button to stop the shore power rectifier.

[0096] When the daily inverter is ready, click the corresponding daily inverter on the touch screen, pop up the daily inverter control interface pop-up window, and press the "start" button to start the daily inverter. When the daily inverter is ready, click the corresponding daily inverter on the touch screen, pop up the daily inverter control interface pop-up window, and press the "stop" button to stop the daily inverter.

[0097] When there is an overload inquiry, the human-computer interaction interface sends an allow signal. In semi-automatic mode, the power is automatically divided; when the BMS "system protection warning" is detected, the propulsion power is automatically limited. When the BMS "system protection shutdown" is detected, the DC / DC is automatically stopped, and the BMS high voltage (shutdown battery) is lowered.

[0098] Regarding the shutdown process, there are three cases: 1. SOC is low (5%), DC / DC is automatically stopped, and BMS high voltage is lowered. 2. Battery system failure, DC / DC is automatically stopped, and BMS high voltage is lowered. 3. BMS protection shutdown is received, DC / DC is automatically stopped, and BMS high voltage is lowered.

[0099] Regarding the fault handling of daily inverter: when two daily inverters supply power to the AC busbar, if one daily inverter fails, the AC busbar is powered by the other daily inverter.

[0100] Regarding battery fault handling: when it is detected that a certain group of lithium batteries reports a system protection warning or overload, the remaining lithium batteries can continue to discharge to ensure that the remaining battery groups discharge according to the maximum discharge power allowed by the BMS. If the continuous discharge power of the lithium battery group is greater than the rated power (0.65C, 544kW) for more than 2 minutes or a certain group of batteries reports a system protection warning, the propulsion power is limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW). After 2 minutes of no fault and no overload of the faulty lithium battery group, the propulsion power limit is removed (can be set), and if the fault occurs again within 10 minutes after the fault is restored, the propulsion power will be immediately limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW).

[0101] Management mode - automatic mode:

[0102] 1) When the power station mode switch is set to "automatic", if neither of the two working modes is selected, the power station is in semi-automatic state.

[0103] 2) Touch screen set lithium battery backup sequence selection, each lithium battery can select the number 1-6, and each lithium battery has a unique number, which is different from other lithium batteries; The smaller the number, the higher the priority of the lithium battery.

[0104] Management mode - navigation mode in automatic mode:

[0105] Backup and running lithium battery ≥ 1 group, solar panel ≥ 1 group can enter navigation mode, the mode can be used lithium battery according to the set start sequence to start running, when PMS detects no lithium battery and solar panel available or other faults, stop mode switching and pop up mode switching failure alarm.

[0106] Automatic function in navigation mode:

[0107] 1) Lithium battery failure: When the lithium battery fails to shut down, it can immediately limit the propulsion power, which will not cause other on-grid power devices to overload trip and cause the whole ship to lose power. After the system dynamic process is restored, the propulsion power limit is removed, and the propulsion load is adjusted to the appropriate demand power value;

[0108] 2) When it is detected that a certain group of lithium batteries reports a system protection warning or overload, the remaining lithium batteries can continue to discharge, ensuring that the remaining battery groups discharge according to the maximum discharge power allowed by the BMS. If the on-grid lithium battery continues to discharge power greater than the rated power (0.65C, 544kW) for more than 2 minutes (can be set) or a certain group of batteries reports a system protection warning, the propulsion power is immediately limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW). After 2 minutes of no fault and no overload of the faulty lithium battery, the propulsion power limit is removed (can be set), and the fault is restored within 10 minutes. If the fault occurs again or overload occurs, the propulsion power will be immediately limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW) Power distribution: For power distribution adjustment, when 6 groups of batteries are online and the SOC difference is significant, the system enters the SOC balancing mode, prioritizing high SOC batteries to output more power. The output power of the high SOC battery is large, and the output power of the low SOC battery is small. When the number of battery groups is less than 6 or the SOC difference is small, the system performs real-time power distribution for lithium battery groups, and performs power distribution.

[0109] 3) Heavy load inquiry: analyze the network power, inquiry failure or allow start feedback. When receiving the left side of the propulsion motor system inquiry signal, if the left bus has lithium battery pack and solar panel to power it, automatically feedback the left side of the propulsion allows running signal, the available power is calculated according to the network power in real time. When receiving the right side of the propulsion motor system inquiry signal, if the right bus has lithium battery pack and solar panel to power it, automatically feedback the right side of the propulsion allows running signal, the available power is calculated according to the network power in real time.

[0110] 4) Lithium battery pack fault recovery self-start machine: when a group of lithium battery pack is stopped due to fault, after artificial recovery of the fault, the system will judge whether it meets the use condition, if it meets the use condition, it will automatically start running.

[0111] 5) Solar panel group fault recovery self-start machine: when a group of solar panels is stopped due to fault, after artificial recovery of the fault, the system will judge whether it meets the use condition, if it meets the use condition, it will automatically start running.

[0112] 6) Lithium battery pack automatic shutdown processing: there are three situations: SOC low (5%), automatic shutdown DC / DC, BMS high voltage; battery system failure, automatic shutdown DC / DC, BMS high voltage; receive BMS protection shutdown, automatic shutdown DC / DC, BMS high voltage.

[0113] Management mode - operation mode in automatic mode:

[0114] Backup and running lithium battery pack is 6 groups, solar panel 2 groups, can enter operation mode, in this mode, the available lithium battery pack starts running according to the set start order, when PMS detects that there is no lithium battery pack available or other faults, stop mode switching and pop up mode switching failure alarm.

[0115] Automatic function in operation mode:

[0116] 1) Lithium battery pack failure: After the lithium battery pack failure shutdown, the propulsion power can be immediately limited, which will not cause other on-grid power devices to overload trip and cause the whole ship to lose power. After the system dynamic process is restored, the propulsion power limit is removed, and the propulsion load is adjusted to the appropriate demand power value. When it is detected that a certain group of lithium batteries reports a system protection warning or overload, the remaining lithium batteries can continue to discharge, ensuring that the remaining battery packs discharge according to the maximum discharge power allowed by the BMS. If the on-grid lithium battery pack continues to discharge power greater than the rated power (0.65C, 544kW) for more than 2 minutes (can be set) or a certain group of batteries reports a system protection warning, the propulsion power is immediately limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW). After 2 minutes of failure of the faulty lithium battery pack without failure or overload, the propulsion power limit is removed (can be set), and the propulsion power is restored within 10 minutes after the failure. If the failure or overload occurs again, the propulsion power will be immediately limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW).

[0117] 2) Power distribution: The system performs real-time power distribution for lithium battery packs, and performs power distribution.

[0118] 3) Heavy load inquiry: Analyze the on-grid surplus power, and perform inquiry failure or allow start feedback. When receiving the left propulsion motor system inquiry signal, if the left bus has lithium battery packs and solar panels supplying power to it, automatically feedback the left propulsion allowed to run signal, and the available power is calculated in real time according to the on-grid surplus power. When receiving the right propulsion motor system inquiry signal, if the right bus has lithium battery packs and solar panels supplying power to it, automatically feedback the right propulsion allowed to run signal, and the available power is calculated in real time according to the on-grid surplus power.

[0119] 4) Lithium battery pack failure recovery self-start: When a certain group of lithium battery packs is shut down due to failure, after the failure is manually restored, the system will determine whether the use conditions are met, and if the use conditions are met, the system will automatically start running.

[0120] 5) Solar panel group failure recovery self-start: When a certain solar panel group is shut down due to failure, after the failure is manually restored, the system will determine whether the use conditions are met, and if the use conditions are met, the system will automatically start running.

[0121] 6) Lithium battery pack automatic shutdown processing: There are three cases: 1. SOC is low (5%), automatically shut down DC / DC, and lower BMS high voltage. 2. Battery system failure, automatically shut down DC / DC, and lower BMS high voltage. 3. Receive BMS protection shutdown, automatically shut down DC / DC, and lower BMS high voltage.

[0122] Management mode - parking mode in automatic mode:

[0123] The standby and running lithium battery pack ≥ 2 groups, solar panel ≥ 1 group can enter the parking mode, the mode uses the highest power of two lithium battery pack discharge, when PMS detects no lithium battery pack available or other failure, stop mode switching and pop mode switching failure alarm.

[0124] Automatic function in parking mode:

[0125] 1) Heavy load inquiry: analyze the power on the network, inquiry failure or allow start feedback. When receiving the left propulsion motor system inquiry signal, automatically return to inquiry failure. When receiving the right propulsion motor system inquiry signal, automatically return to inquiry failure.

[0126] 2) Automatic equalization of battery power: 1. Automatically start the discharge of the two lithium battery packs with the highest power. At the same time, the solar panel continues to discharge. 2. After 1 hour of lithium battery pack operation on the network, automatically start the lithium battery pack with the highest power except the lithium battery pack and stop the lithium battery pack. 3. If the lithium battery pack with the highest power is more than 5% higher than the lithium battery pack with the lowest power among all lithium battery packs, and the difference between the SOC of the lithium battery on the network and the lowest value of the SOC of the six lithium battery packs is less than 5%, automatically start the lithium battery pack with the highest power except the lithium battery pack and stop the lithium battery pack.

[0127] 3) Power distribution: the system distributes power to the lithium battery pack on the network in real time, and performs power equalization.

[0128] 4) Lithium battery pack fault recovery self-start: after manually recovering the fault of a lithium battery pack that has been stopped due to a fault, the system will determine whether the use conditions are met. If the use conditions are met, automatically start running.

[0129] 5) Solar panel fault recovery self-start: after manually recovering the fault of a solar panel that has been stopped due to a fault, the system will determine whether the use conditions are met. If the use conditions are met, automatically start running.

[0130] 6) Automatic shutdown of lithium battery pack: there are three cases: 1. SOC is low (5%), automatically stop DC / DC and lower BMS high voltage. 2. Battery system failure, automatically stop DC / DC and lower BMS high voltage. 3. Receive BMS protection shutdown, automatically stop DC / DC and lower BMS high voltage.

[0131] 7) Automatic standby machine start: when the lithium battery pack on the network fails to start, automatically start the standby lithium battery pack.

[0132] Charging mode in management mode - automatic mode:

[0133] In charging mode, the bus switch is automatically opened, the shore power rectifier automatically starts the generator, and the fault-free lithium battery pack automatically starts charging. When the propulsion is running or other faults occur, the stop mode switches and pops up a mode switching failure alarm.

[0134] The system calculates the maximum allowed charging power of each lithium battery pack according to the output power of the shore power rectifier and the maximum allowed charging current issued by the BMS system to charge.

[0135] When the lithium battery pack is full and the shore power rectifier is stopped, the charging is automatically disconnected, the DC / DC is stopped, and the BMS high voltage is lowered.

[0136] Regarding heavy load inquiries, when the propulsion motor system inquires, an inquiry failure alarm is issued.

[0137] 1. The system uses bus voltage droop control + adaptive weight distribution algorithm to realize power dynamic balance. The core formula is:

[0138] Output power Pi = P ref_batt + Kv x (Vdc - Vref) + Ks x (SOCi - SOCavg)

[0139] Where Pi is the output power of the i-th battery, P ref_batt is the reference value of the lithium battery pack power (unit: kW), which is usually obtained by dividing the total power demand minus the real-time solar output by the number of online lithium battery packs, i.e. P ref_batt ≈ (total demand power - total solar output) / N_online_batt, where N_online_batt is the number of online lithium battery packs. It represents the average power that the battery pack should share in the ideal state without voltage deviation and SOC deviation. Vdc is the DC bus voltage, SOCi is the state of charge of the i-th single battery, and SOCavg is the average SOC of the online battery pack. The coefficient Kv adjusts the voltage deviation weight, and Ks adjusts the SOC balancing weight.

[0140] Kv (voltage compensation coefficient): when the DC bus voltage Vdc deviates from the reference voltage value Vref, automatically adjust the power compensation amount;

[0141] Ks (SOC balancing coefficient): dynamically adjust the output according to the real-time state of charge deviation of the battery pack (high SOC battery pack Ks is set to a positive value to increase output; low SOC group is negative to reduce output).

[0142] Integration and processing of solar panels:

[0143] The solar panels are connected to the DC bus through their dedicated photovoltaic frequency converter.

[0144] The solar panel output (P_solar_j) is independently controlled by its own maximum power point tracking, aiming to maximize the capture of solar energy under current lighting conditions.

[0145] Roles in the power distribution formula:

[0146] The solar panel output (P_solar) is not directly controlled by the above lithium battery power distribution formula. For the lithium battery pack: P ref_batt It needs to be calculated according to (total power demand - real-time total solar output P_solar). The target total output of the lithium battery pack is the remaining part after subtracting the real-time contribution of solar energy from the total demand of the system.

[0147] Droop control (Kv term): All power sources connected to the DC bus, including lithium battery packs and solar inverters, are essentially involved in maintaining the stability of the bus voltage. The droop control (Kv term) of the lithium battery pack responds to changes in bus voltage, working together with the voltage control of the solar inverter to stabilize V_dc.

[0148] SOC equalization (Ks term): This part is only for SOC equalization adjustment of the lithium battery pack, and has nothing to do with the solar panel.

[0149] Mode switching logic:

[0150] Equal distribution mode: When the SOC difference between online battery packs is <5%, power equalization is the main mode, ensuring that the output deviation of each battery pack is <3%.

[0151] SOC equalization mode: When the maximum difference in SOC between online battery packs is ≥5% and lasts for 5 minutes, automatically switch to SOC equalization mode, forcing high-SOC batteries to output preferentially (up to 110% of rated power), and low-SOC batteries to reduce load to 50%, until the SOC difference between online battery packs narrows to ≤2%.

[0152] 2. Implementation of SOC equalization mode:

[0153] Trigger mechanism:

[0154] Basic judgment condition: The system monitors the state of charge (SOC) of all 6 lithium batteries in real time. When the difference between the highest and lowest SOC values reaches or exceeds 5%, trigger the preliminary judgment;

[0155] Duration verification: The above difference continues to exceed the limit for ≥5 minutes (to eliminate transient fluctuation interference), and the SOC equalization mode is officially activated.

[0156] Power dynamic allocation algorithm:

[0157] Calculate the SOC deviation rate of each battery:

[0158] Control rules:

[0159] High SOC battery pack (ΔSOC i >0) to increase output, the upper limit is 110% of the rated power;

[0160] Low SOC battery pack (ΔSOC i <0) to reduce output, the lower limit is 50% of the rated power;

[0161] Exit condition: the SOC difference between all online battery packs falls within 2%, automatically switching back to power sharing mode.

[0162] 3. In full mode, high and low pressure:

[0163] BMS high voltage process is executed in three steps:

[0164] 1) BMS self-test: insulation resistance > 3MΩ, cell temperature difference < 5℃, no internal short circuit;

[0165] 2) Pre-charge: through the current limiting resistor to slowly raise the battery voltage to 80% of the DC bus voltage;

[0166] 3) Main contactor closed: soft start of frequency converter, 10ms to complete grid connection.

[0167] The three steps are completed, the main contactor is closed, which represents the high voltage.

[0168] BMS low voltage conditions include:

[0169] Hard threshold (directly trigger low voltage): when any of the following conditions are met, BMS will directly execute low voltage operation (open main contactor): 1. SOC ≤ 5% (to prevent over-discharge), 2. Full charge (battery is fully charged, to prevent overcharge), 3. Temperature > 55℃ (risk of thermal runaway);

[0170] Fault response (trigger low voltage): BMS reports system protection shutdown (such as insulation fault), 100ms to cut off the high voltage.

[0171] Mode differentiation (low voltage execution strategy):

[0172] Navigation mode, low voltage (open contactor) action delay < 200ms. (Purpose: to ensure emergency maneuvering capability and avoid instant power failure leading to loss of control)

[0173] Charging mode, the contactor is allowed to be closed only after the shore power rectifier synchronization signal is ready.

[0174] 4. Processing mechanism for heavy load inquiry:

[0175] The heavy load device can be started only when the grid surplus power is greater than the starting power of the heavy load device.

[0176] The parking mode directly rejects, and the HMI interface displays "surplus power gap XX kW" and the list of non-critical loads that need to be closed.

[0177] 5. Conditions for automatic start of fault recovery:

[0178] 1) Restarting conditions for lithium battery pack:

[0179] After the fault is eliminated, the battery pack state of charge (SOC) needs to be higher than 20%, ensuring basic discharge capability;

[0180] The battery temperature must be restored to the safe working interval of 10°C-45°C;

[0181] The insulation resistance value is greater than 2MΩ, excluding the risk of electric leakage;

[0182] The cumulative number of restarts within 24 hours does not exceed twice, avoiding frequent actions that cause damage to the device.

[0183] 2) Restarting conditions for solar panels:

[0184] The fault is eliminated and the ambient light intensity continues to be higher than 200W / m 2 for more than 5 minutes;

[0185] 3) Safety precautions:

[0186] The output power is limited to 80% of the rated value within 10 minutes after the device restarts to prevent secondary fault impact; if the same device restarts again within 24 hours after the fault occurs, the system is automatically locked and triggers the "manual intervention required" alarm, disabling the self-start function.

[0187] 6. Thrust power limitation parameters:

[0188] If the lithium battery pack continues to discharge power greater than the rated power (0.65C, 544kW) for more than 2 minutes (can be set) or a group of batteries reports a system protection warning, the thrust power will be limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW). After 2 minutes of fault-free and overload-free lithium battery pack, the thrust power limitation is removed (can be set), and if the fault occurs again within 10 minutes after recovery, the thrust power will be immediately limited (the maximum discharge power of each lithium battery is limited to 0.60C, 500kW).

[0189] The system realizes fine control of thrust power through a three-level linkage mechanism:

[0190] Classification of load limiting trigger rules:

[0191] Primary limit: When the single group of lithium batteries continuously discharges power exceeding the rated power of 0.65C (544kW) for more than 2 minutes, the load is automatically reduced to 0.60C (500kW);

[0192] Secondary limit: If the battery management system (BMS) issues a temperature warning (≥50℃) or a voltage anomaly warning, the global propulsion power is immediately reduced to 70% of the rated value;

[0193] Tertiary limit: When the battery SOC is lower than 15%, a stepwise load reduction is performed (for every 5% reduction in SOC, the propulsion power limit is reduced by 20%).

[0194] Health state related adjustment:

[0195] Introducing a battery health state (SOH) compensation algorithm: When the SOH is lower than 85%, the rated power reference value is automatically reduced by 5% (for example, 0.65C is adjusted to 0.62C);

[0196] Temperature compensation mechanism: In the BMS temperature warning state, for every 1℃ increase in temperature, an additional 2% power reduction is added.

[0197] Dynamic recovery logic:

[0198] Limit removal requires simultaneous satisfaction: fault elimination for 2 minutes, temperature back to below 45℃, and SOC back to above 20%.

[0199] The above-described embodiments only express the specific implementation of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A power and energy management system for an electric tugboat, characterized in that, DC 1000V direct current power distribution architecture as the basis of the system; 2n groups of lithium batteries, 2m groups of solar panels, and 2 shore power rectifiers connected to the high-voltage power distribution board form multiple energy sources; 2n groups of lithium batteries and 2m groups of solar panels supply power to the DC bus through one-to-one corresponding DC power distribution board frequency converters and photovoltaic frequency converters; 2n groups of lithium batteries can be charged through 2n groups of DC power distribution board frequency converters and 2 shore power rectifiers connected to the high-voltage power distribution board; 2n groups of lithium batteries are connected in parallel and automatically load balanced between each other; 2 daily inverters and corresponding daily transformers are connected in series as a group of loads between the DC bus and the AC power distribution board, and the main propulsion motor connected to the DC bus through the main propulsion inverter is another group of loads, and the DC bus and the AC power distribution board are connected in series to realize load segment power supply and redundant backup; The automatic control system includes but is not limited to the power management system, the battery management system, and the daily inverter control system; in different working conditions, the bus voltage droop control + adaptive weight distribution algorithm is used to realize power dynamic balance; The safety management sampling rapid fault recovery mechanism includes automatic shutdown DC / DC module, high and low voltage and power limit management of the battery management system, and automatic start of fault recovery.

2. The electric tugboat power and energy management system of claim 1, wherein, The core formula of the bus voltage droop control + adaptive weight distribution algorithm is: Output power Pi = P ref_batt + Kv x (Vdc - Vref) + Ks x (SOCi - SOCavg) where Pi is the output power of the i-th battery group; P ref_batt is the reference value of the lithium battery group, which is usually obtained by dividing the total power demand minus the real-time output of solar energy according to the number of online lithium battery groups, that is, P ref_batt ≈(total demand power-total solar output) / N_online_batt, where N_online_batt is the number of online lithium battery groups, which represents the average power that the battery group should share in the ideal state without voltage deviation and SOC deviation; Vdc is the DC bus voltage, SOCi is the state of charge of the i-th single battery group, SOCavg is the average SOC of the online battery group, the coefficient Kv adjusts the voltage deviation weight, and the coefficient Ks adjusts the SOC balancing weight; Voltage compensation coefficient Kv: when the DC bus voltage Vdc deviates from the reference voltage value Vref, the power compensation amount is automatically adjusted; SOC balancing coefficient Ks: dynamically adjust the output according to the real-time state of charge deviation of the battery pack, set Ks to a positive value for high SOC battery pack to increase output, and set Ks to a negative value for low SOC battery pack to reduce output; Mode switching logic: Equal distribution mode: when the SOC difference between online battery packs is <5%, power equalization is given priority to ensure that the output deviation of each battery pack is <3%; SOC balancing mode: when the maximum SOC difference between online battery packs is ≥5% and lasts for 5 minutes, automatically switch to SOC balancing mode, force high SOC battery to output first, and low SOC battery to reduce load to 50%, until the SOC difference between online battery packs is narrowed to ≤2%.

3. The electric tugboat power and energy management system of claim 2, wherein, The implementation method of the SOC balancing mode is: The system monitors the state of charge of all 2n groups of lithium batteries in real time, and when the difference between the highest and lowest SOC values reaches or exceeds 5%, the preliminary judgment is triggered; Continuous duration verification: the above difference continues to exceed the limit for ≥5 minutes, 5 minutes is used to eliminate transient fluctuation interference, and the SOC balancing mode is activated; Power dynamic distribution algorithm: The SOC deviation rate of each group of batteries is calculated: Control rules: High SOC battery pack (ΔSOC i >0) to boost output, with an upper limit of 110% of rated power. Low SOC battery pack (ΔSOC i <0) reduce output, lower limit 50% of rated power; Exit condition: the SOC difference between all online battery packs falls within 2%, and automatically switches back to power equalization mode.

4. The electric tugboat power and energy management system of claim 2, wherein, The solar panels are connected to the DC bus through their dedicated photovoltaic frequency converters, and the output P_solar_j of the solar panels is independently controlled by the maximum power point tracking of the solar panels.

5. The electric tug boat power and energy management system of claim 1, wherein, The high and low voltage limit management of the battery management system: The high voltage is executed in three steps: 1) Battery management system self-check: insulation resistance > 3MΩ, cell temperature difference < 5℃, no internal short circuit flag; 2) Pre-charge: slowly raise the battery voltage to 80% of the DC bus voltage through a current-limiting resistor; 3) Main contactor closed: soft start of the frequency converter, complete grid connection within 10ms; After the completion of the three steps, the main contactor is closed, which represents the upper high voltage; The lower high voltage conditions include: Hard threshold: when any of the following conditions is met, the battery management system will directly perform the lower high voltage operation and disconnect the main contactor, condition 1: over-discharge prevention SOC ≤ 5%, condition 2: fully charged, condition 3: thermal runaway risk temperature > 55℃; Fault response, trigger lower high voltage: when the battery management system reports system protection shutdown, cut off the high voltage within 100ms; Mode differentiation: Navigation mode, lower high voltage action delay < 200ms, ensure emergency maneuvering and avoid instant power failure leading to loss of control; Charging mode, the contactor is allowed to be closed only after the shore power rectifier synchronization signal is ready.

6. The electric tug boat power and energy management system of claim 1, wherein, The conditions for automatic start of fault recovery are: 1) Lithium battery pack restart conditions: After the fault is eliminated, the battery pack state of charge (SOC) needs to be higher than 20% to ensure basic discharge capability; The battery temperature must be restored to the safe working interval of 10℃-45℃; The insulation resistance value is greater than 2MΩ to exclude the risk of electric leakage; The cumulative restart frequency within 24 hours is not more than twice to avoid frequent actions causing equipment damage; 2) Solar panel restart conditions: Failure elimination and ambient light intensity continuously above 200 W / m 2 for more than 5 minutes; 3) Safety protection measures: Within 10 minutes after the device restarts, the output power is limited to 80% of the rated value to prevent secondary fault impact; If the same device fails again within 24 hours after restarting, the system automatically locks and triggers the "manual intervention" alarm, disabling the self-start function.

7. The electric tug boat power and energy management system of claim 1, wherein, The system has three working modes: manual, semi-automatic and automatic modes, which can be selected by soft buttons on the touch screen. If none of the above modes is selected, the power station is in semi-automatic mode. The automatic mode includes discharge mode and charging mode, and the discharge mode is divided into navigation mode, operation mode and parking mode.

8. The electric tugboat power and energy management system of claim 7, wherein, The navigation mode in the automatic mode: When there are ≥1 spare and running lithium battery packs and ≥1 solar panels, the navigation mode can be entered. In this mode, the available lithium battery packs are started according to the set start order. When no lithium battery pack and solar panel are available or other faults are detected, the mode switching is stopped and a mode switching failure alarm is popped up; The operation mode in the automatic mode: When there are 2n spare and running lithium battery packs and 2m solar panels, the operation mode can be entered. In this mode, the available lithium battery packs are started according to the set start order. When no lithium battery pack is available or other faults are detected, the mode switching is stopped and a mode switching failure alarm is popped up; The parking mode in the automatic mode: When there are ≥2 spare and running lithium battery packs and ≥1 solar panels, the parking mode can be entered. In this mode, the two lithium battery packs with the highest power consumption are discharged. When no lithium battery pack is available or other faults are detected, the mode switching is stopped and a mode switching failure alarm is popped up; The charging mode in the automatic mode: The mother joint switch is automatically opened, the shore power rectification is automatically started, the lithium battery pack is automatically started and charged without failure; when the propulsion is running or other faults occur, the mode switching is stopped and the mode switching failure alarm is popped up.

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