Control method of energy storage device, energy storage device and power supply system

Abstract

The application provides a control method of an energy storage device, the energy storage device and a power supply system. The method comprises the following steps: when an AC bus is disconnected from a power grid, obtaining a battery voltage of a battery pack, a load current of a load, an output voltage of an AC end, an output current of the AC end and a maximum power generation of a generator; obtaining a voltage deviation value between a given DC bus voltage and the battery voltage; performing deviation adjustment on the voltage deviation value to determine a reference current; when the reference current is less than 0, determining that the energy storage device is in a charging mode; in the charging mode, determining a maximum charging power according to the maximum power generation, the output voltage and the load current; performing amplitude limiting processing on the reference current based on the maximum charging power to determine a target given current; and generating a control signal according to the target given current and the output current, wherein the control signal is used to adjust the output current of the AC end of a bidirectional inverter circuit. The control method of the energy storage device can reduce the probability of overloading of the generator and being flooded.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a control method for an energy storage device, an energy storage device, and a power supply system. Background Technology

[0002] With increasing global emphasis on environmental protection and sustainable development, traditional fossil fuels are gradually being replaced by renewable energy sources. However, renewable energy sources (such as solar and wind power) are intermittent and unstable, making energy storage devices a key technology for addressing this issue. Energy storage devices can store excess electricity generated by solar or wind power for use when needed, thereby improving energy efficiency.

[0003] After a power grid outage, energy storage devices can serve as backup power for a certain period, but they cannot provide electricity for an extended period. Therefore, parallel operation of energy storage devices with generators, such as fuel-fired generators, is a hybrid power supply solution that improves power supply reliability and optimizes energy utilization. However, there are many challenges in parallel operation of energy storage devices and fuel-fired generators, with dynamic power distribution and load impact being the most critical aspects.

[0004] For example, if energy storage devices and fuel generators supply power to a load simultaneously, it may cause power oscillations or overloads; when large loads are switched on or off, it may cause reverse current flow from the energy storage device to the fuel generator, damaging the generator; when the fuel generator is charging the energy storage device, a sudden load connection may cause the fuel generator to overload and shut down. Therefore, a control method is urgently needed to achieve good parallel operation of energy storage devices and generators. Summary of the Invention

[0005] In view of this, this application provides a control method for an energy storage device, an energy storage device, and a power supply system. When the energy storage device and the generator are running in parallel, not only can the rapid switching of charging and discharging of the energy storage device be realized, but the probability of the generator being overloaded or overloaded can also be reduced.

[0006] This application provides a control method for an energy storage device, which includes a battery pack, a DC bus, and a bidirectional inverter circuit. The DC terminal of the bidirectional inverter circuit is connected to the battery pack via the DC bus, and the AC terminal of the bidirectional inverter circuit is connected to an AC bus. The AC bus is also used to connect a generator, a power grid, and a load. The method includes: when the AC bus is disconnected from the power grid, acquiring the battery voltage of the battery pack, the load current of the load, the output voltage of the AC terminal, the output current of the AC terminal, and the maximum power output of the generator; acquiring the voltage deviation value between a given DC bus voltage and the battery voltage; adjusting the voltage deviation value to determine a reference current; determining that the energy storage device is in charging mode when the reference current is less than 0; in charging mode, determining the maximum charging power based on the maximum power output, the output voltage, and the load current; limiting the reference current based on the maximum charging power to determine a target given current; and generating a control signal based on the target given current and the output current, the control signal being used to adjust the output current of the AC terminal of the bidirectional inverter circuit.

[0007] In one embodiment, the method further includes: determining that the energy storage device is in a discharge mode when the reference current is greater than or equal to 0; determining a tracking coefficient based on the reference current and a proportional coefficient in the discharge mode; and determining a target given current based on the tracking coefficient and the load current; wherein 0 < tracking coefficient ≤ 1, and the tracking coefficient is positively correlated with the remaining energy of the battery pack.

[0008] In one embodiment, before determining the target given current based on the tracking coefficient and the load current, the method further includes: limiting the tracking coefficient by a preset limiter to limit the tracking coefficient to a range of 0 to 1.

[0009] In one embodiment, determining the maximum charging power based on the maximum power generation, output voltage, and load current includes: determining the load power based on the output voltage and load current; and determining the maximum charging power based on the maximum power generation and load power.

[0010] In one embodiment, limiting the reference current based on the maximum charging power to determine the target given current includes: determining the maximum charging current based on the maximum charging power and the output voltage; and limiting the reference current based on the maximum charging current to determine the target given current.

[0011] In one embodiment, limiting the reference current based on the maximum charging current to determine the target given current includes: limiting the reference current based on the maximum charging current to obtain a given current amplitude; performing phase-locking on the AC bus voltage to obtain the synchronization phase angle of the AC bus voltage; and determining the target given current based on the synchronization phase angle and the given current amplitude.

[0012] In one embodiment, the reference current is limited based on the maximum charging current to obtain a given current amplitude, including: when the absolute value of the reference current is less than or equal to the maximum charging current, the reference current is used as the given current amplitude; when the absolute value of the reference current is greater than or equal to the maximum charging current, the maximum charging current is used as the given current amplitude.

[0013] In one embodiment, generating a control signal based on a target given current and an output current includes: determining a current deviation value based on the target given current and the output current; adjusting the current deviation value to determine a voltage adjustment amount; determining a modulation voltage based on the voltage adjustment amount and the output voltage; and generating a control signal based on the modulation voltage.

[0014] A second aspect of this application provides an energy storage device, including a battery pack, a DC bus, a bidirectional inverter circuit, and a controller. The DC terminal of the bidirectional inverter circuit is connected to the battery pack via the DC bus, and the AC terminal of the bidirectional inverter circuit is connected to an AC bus. The AC bus is also used to connect a generator, a power grid, and a load. The controller is used to execute the control method of the energy storage device as described in any of the preceding claims.

[0015] A third aspect of this application provides a power supply system including a generator and the aforementioned energy storage device. Both the generator and the energy storage device are connected to an AC bus, which is also used to connect a load.

[0016] The control method for the energy storage device provided in this application acquires the battery voltage of the battery pack, the load current of the load, the output voltage and current of the AC terminal, and the maximum power output of the generator when the AC bus is disconnected from the power grid. Then, it adjusts the voltage deviation between the given DC bus voltage and the battery voltage to determine the reference current at the AC terminal. Since the power transmission direction is defined as positive when the energy storage device discharges to the AC bus and negative when the energy storage device draws power from the AC bus, the energy storage device is determined to be in charging mode when the reference current is less than 0. At this time, the generator's power output is used to supply power to the energy storage device and the load. Therefore, ideally, the maximum charging power of the energy storage device is the generator's maximum power output minus the power consumed by the load. Furthermore, since both the energy storage device and the load are connected to the AC bus, the voltage at the connection port of the load to the AC bus is the same as the output voltage of the AC terminal. Thus, the maximum charging power of the energy storage device can be determined based on the generator's maximum power output, output voltage, and load current. The reference current is then limited based on the maximum charging power to determine the target current. A control signal is generated based on the target current and the output current to adjust the output current at the AC terminal of the bidirectional inverter circuit. This limits the output current at the AC terminal of the bidirectional inverter circuit, reducing the probability of excessive power draw from the AC bus by the energy storage device, leading to generator overload tripping. In summary, the energy storage device control method provided in this application effectively reduces the probability of generator overload tripping when the energy storage device and generator are operating in parallel and the energy storage device is in charging mode. Furthermore, the energy storage device control method provided in this application allows the energy storage device to operate in current source mode, resulting in better load current tracking characteristics and faster dynamic response, thus facilitating rapid switching between charging and discharging modes of the energy storage device. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation on the scope of protection of this application. In the various drawings, similar components are numbered similarly.

[0018] Figure 1 This is a schematic diagram illustrating an application scenario of the control method for an energy storage device in one embodiment of this application.

[0019] Figure 2 This is a schematic flowchart of a control method for an energy storage device provided in an embodiment of this application.

[0020] Figure 3 This is a flowchart illustrating the process when the reference current is greater than 0 after step S203 is executed in one embodiment of this application.

[0021] Figure 4 This is a flowchart illustrating a sub-step of step S205 in one embodiment of this application.

[0022] Figure 5 This is a flowchart illustrating a sub-step of step S206 in one embodiment of this application.

[0023] Figure 6 This is a flowchart illustrating a sub-step of step S502 in one embodiment of this application.

[0024] Figure 7 This is a flowchart illustrating a sub-step of step S207 in one embodiment of this application.

[0025] Figure 8 A detailed control block diagram of a control method for an energy storage device provided in an embodiment of this application.

[0026] Figure 9 This is a block diagram of an electronic device provided in an embodiment of this application.

[0027] Figure 10 A functional block diagram of a computer-readable storage medium provided in an embodiment of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0029] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have an intervening component. When a component is considered to be "placed" on another component, it can be directly placed on the other component or may also have an intervening component. The terms "top," "bottom," "upper," "lower," "left," "right," "front," "back," and similar expressions used in this article are for illustrative purposes only.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0031] Some embodiments will now be described with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] With increasing global emphasis on environmental protection and sustainable development, traditional fossil fuels are gradually being replaced by renewable energy sources. However, renewable energy sources (such as solar and wind power) are intermittent and unstable, making energy storage devices a key technology for addressing this issue. Energy storage devices can store excess electricity generated by solar or wind power for use when needed, thereby improving energy efficiency.

[0033] After a power grid outage, energy storage devices can serve as backup power for a certain period, but they cannot provide electricity for an extended period. Therefore, parallel operation of energy storage devices with generators, such as fuel-fired generators, is a hybrid power supply solution that improves power supply reliability and optimizes energy utilization. However, there are many challenges in parallel operation of energy storage devices and fuel-fired generators, with dynamic power distribution and load impact being the most critical aspects.

[0034] For example, if energy storage devices and fuel generators supply power to a load simultaneously, it may cause power oscillations or overloads; when large loads are switched on or off, it may cause reverse current flow from the energy storage device to the fuel generator, damaging the generator; when the fuel generator is charging the energy storage device, a sudden load connection may cause the fuel generator to overload and shut down. Therefore, a control method is urgently needed to achieve good parallel operation of energy storage devices and generators.

[0035] Therefore, this application provides a control method for an energy storage device, an energy storage device, and a power supply system, so that when the energy storage device and the generator are running in parallel, not only can the rapid switching of charging and discharging of the energy storage device be realized, but also a good dynamic power distribution between the energy storage device and the generator under load fluctuations can be achieved, reducing the probability of the generator being overloaded or overloaded.

[0036] Please see Figure 1 , Figure 1 This is a schematic diagram illustrating an application scenario of the control method for an energy storage device in one embodiment of this application. Figure 1 A power supply system 100 is shown, including an energy storage device 10 and a generator 20. The energy storage device 10 is connected to an AC bus 30, and the AC bus 30 is also used to connect the generator 20, the power grid 40, and a load 50.

[0037] The energy storage device 10 includes a battery pack 11, a DC bus 12, a bidirectional inverter circuit 13, and a controller 14. The DC terminal (DC) of the bidirectional inverter circuit 13 is connected to the battery pack 11 via the DC bus 12, and the AC terminal (AC) of the bidirectional inverter circuit 13 is connected to the AC bus 30. The controller 14 is communicatively connected to at least the bidirectional inverter circuit 13 and the battery pack 11 to control their coordinated operation. In some embodiments, the battery pack 11 includes one or more cells connected in series and / or parallel for storing or releasing energy. The bidirectional inverter circuit 13 is used to draw power from the DC bus 12 to convert power and output AC power to the AC bus 30 when the battery pack 11 is discharging, or to draw power from the AC bus 30 to convert power and output DC power to the DC bus 12 to charge the battery pack 11. The bidirectional inverter circuit 13 may include, for example, a buck-boost circuit; this application does not limit the specific circuit structure of the bidirectional inverter circuit 13. The controller 14 may include a central processing unit (CPU), other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, etc. In some embodiments, the energy storage device 10 also integrates a maximum power point tracking (MPPT) module, and the DC bus 12 is also connected to a power generation device (not shown in the figure). The MPPT module is used to perform maximum power point tracking on the input power of the power generation device, so as to convert the input power of the power generation device into power to charge the battery cells, and / or output it to the bidirectional inverter circuit 13 through the DC bus 12, where the bidirectional inverter circuit 13 converts the power and outputs it through the AC terminal. The power generation device may be, for example, a photovoltaic power generation device, a wind power generation device, etc.

[0038] Generator 20 can be a device that includes both power generation and power supply functions, used to output alternating current to AC bus 30. That is, generator 20 may include a power generation unit and a power supply unit for energy control. Generator 20 may be, for example, but not limited to, diesel generators, gasoline generators, gas generators, wind turbines, hydroelectric generators, multi-fuel generators, etc., without limitation.

[0039] The power grid 40 may be, for example, a municipal power grid or other power distribution system. This application does not limit the type of AC power in the power grid 40; for example, the power grid 40 may be single-phase AC, split-phase AC, three-phase AC, or other multi-phase AC.

[0040] Load 50 is used to draw power from at least one of the power grid 40, generator 20, and energy storage device 10 to meet the power consumption required for operation. Load 50 can be various electrical appliances, such as refrigerators, air conditioners, electric vehicles, etc., and this application does not limit the specific type of load 50.

[0041] In some embodiments, the generator 20 is connected to the AC bus 30 via a first switch S1, and the common terminal of the energy storage device 10, the generator 20, and the load 50 on the AC bus 30 is also connected to the power grid 40 via a second switch S2. Thus, when the power grid 40 is supplying power normally, the second switch S2 is closed and the first switch S1 is open, allowing the power grid 40 to supply power to the load 50 and the energy storage device 10, or the power grid 40 and the energy storage device 10 to jointly supply power to the load 50. When the power grid 40 is abnormal, the first switch S1 is closed and the second switch S2 is open, allowing the generator 20 to supply power to the load 50 and the energy storage device 10, or the generator 20 and the energy storage device 10 to jointly supply power to the load 50.

[0042] It is worth noting that, Figure 1 Although the application scenario shown includes one energy storage device 10 and one generator 20, in other embodiments, multiple generators 20 and / or multiple energy storage devices 10 may be connected to the AC bus 30. This application does not limit the number of generators 20 and energy storage devices 10 connected to the AC bus 30.

[0043] It is understood that the control method for energy storage devices provided in this application, in addition to being applied to... Figure 1 The energy storage device 10 shown in the application scenario can also be applied to other application environments that require parallel operation of the energy storage device 10 and the generator 20. Figure 1 The illustrated application environment diagram does not limit the control method, energy storage device, and power supply system of the energy storage device provided in this application.

[0044] Please see Figure 2 , Figure 2 This is a schematic flowchart illustrating a control method for an energy storage device according to an embodiment of this application. It is understood that this method can be executed by the controller 14 of the energy storage device 10. The method includes the following steps S201 to S207.

[0045] Step S201: When the AC bus is disconnected from the power grid, obtain the battery voltage of the battery pack, the load current of the load, the output voltage of the AC terminal, the output current of the AC terminal, and the maximum power generation of the generator.

[0046] In some embodiments, the controller 14 can obtain the battery voltage and the AC output voltage by sampling the voltage at the battery port and the AC terminal of the battery pack 11, respectively; and obtain the load current and the output current by sampling the current at the connection port between the load 50 and the AC bus 30 and the AC terminal, respectively. Simultaneously, the controller 14 can communicate with the generator 20 to obtain the maximum power output of the generator 20.

[0047] In other embodiments, the controller 14 can also communicate with the battery pack 11 to receive the battery voltage periodically reported by the battery pack 11. Simultaneously, the controller 14 can also communicate with the load 50 to obtain the load current of the load 50. In other embodiments, the maximum power output of the generator 20 can be preset in the memory of the energy storage device 10, or the maximum power output of the generator 20 can be obtained in response to user operations, such as in response to a customer's interaction with the energy storage device 10, or the maximum power output of the generator 20 can be obtained by receiving data from a host computer.

[0048] This application does not limit the specific method of obtaining the battery voltage of the battery pack 11, the load current of the load 50, the output voltage of the AC terminal, the output current of the AC terminal, and the maximum power generation of the generator 20 in step S201, nor does it limit the specific circuit of the voltage sampling circuit and the current sampling circuit of the energy storage device 10.

[0049] In some embodiments, before acquiring the battery voltage of the battery pack 11, the load current of the load 50, the output voltage of the AC terminal, the output current of the AC terminal, and the maximum power output of the generator 20, the energy storage device 10 may sample at least one of the output voltage, output current, and output power of the AC terminal to determine whether the AC bus 30 is disconnected from the power grid 40 based on at least one of the output voltage, output current, and output power of the AC terminal. It is understood that when the AC bus 30 is disconnected from the power grid 40, the waveform of the output voltage of the AC terminal may change from a sine wave to a non-sine wave, causing at least one of the output voltage, output current, and output power to change. Thus, the energy storage device 10 can determine that the AC bus 30 is disconnected from the power grid 40 by sampling at least one of the output voltage, output current, and output power of the AC terminal, provided that at least one of the output voltage, output current, and output power meets a preset condition.

[0050] In other embodiments, a grid disconnection notification may be sent to the energy storage device 10 by a host computer or any device connected to the AC bus 30, causing the energy storage device 10 to determine that the AC bus 30 is disconnected from the grid 40. This application does not limit the specific method by which the energy storage device 10 determines that the AC bus 30 is disconnected from the grid 40.

[0051] Step S202: Obtain the voltage deviation value between the given DC bus voltage and the battery voltage.

[0052] In some embodiments, the difference between a given DC bus voltage and the battery voltage can be used as the voltage deviation value.

[0053] When the voltage deviation is greater than 0, it indicates that the given DC bus voltage is greater than the battery voltage. In this case, the bus voltage is controlled according to the given DC bus voltage, causing the voltage on the DC bus 12 to flow to the battery pack 11, thereby charging the battery pack 11. Furthermore, the voltage on the DC bus 12 is obtained from the AC bus 30 by the bidirectional inverter circuit 13, undergoes power conversion, and is then output to the DC bus 12. Therefore, the energy storage device 10 will be in charging mode at this time.

[0054] When the voltage deviation is less than 0, it indicates that the given DC bus voltage is less than the battery voltage. In this case, the bus voltage is controlled according to the given DC bus voltage, causing the battery voltage of battery pack 11 to flow to DC bus 12, thus discharging battery pack 11 to DC bus 12. In this way, the bidirectional inverter circuit 13 can obtain DC power from DC bus 12 and perform power conversion to output AC power to AC bus 30. At this time, the energy storage device 10 will be in discharge mode.

[0055] Step S203: Adjust the voltage deviation value to determine the reference current.

[0056] The reference current is used to represent the reference value of the output current of the AC terminal when the bus voltage on the DC bus 12 is adjusted according to the given DC bus voltage.

[0057] Understandably, the deviation control algorithm mentioned in this document can be a PI (Proportional Integral) control algorithm, a PID (Proportional Integral Differential) control algorithm, or other control algorithms. PI, PID, or other control algorithms used to achieve deviation control typically include proportional and / or integral parameters. These proportional and integral parameters can be positive or negative, and this application does not impose any restrictions on their specific values.

[0058] In this embodiment, the power transmission direction when the energy storage device 10 discharges to the AC bus 30 is defined as positive, and the power transmission direction when the energy storage device 10 draws power from the AC bus 30 is defined as negative. Thus, in step S203, the proportional and / or integral parameters in the adjustment algorithm can be configured to be negative, so that the polarity of the reference current obtained after adjusting the voltage deviation value is opposite to the polarity of the voltage deviation value, thereby matching the polarity of the reference current with the defined power flow direction.

[0059] Of course, in other embodiments, the positive and negative directions can be reversed, depending on the actual situation, and all are within the protection scope of this application.

[0060] Step S204: When the reference current is less than 0, determine that the energy storage device is in charging mode.

[0061] In this embodiment, since the polarity of the reference current is opposite to the polarity of the voltage deviation value, when the reference current is less than 0, it indicates that the voltage deviation value is greater than 0, and it can be determined that the energy storage device 10 is in charging mode.

[0062] Step S205: In charging mode, determine the maximum charging power based on the maximum power generation, output voltage, and load current.

[0063] It is understood that when the energy storage device 10 is in charging mode, the power output of the generator 20 is used to supply power to both the energy storage device 10 and the load 50. Therefore, if the charging power of the energy storage device 10 and the power consumed by the load 50 exceed the maximum power output of the generator 20, the generator 20 may become overloaded. Thus, it is necessary to limit the charging power of the energy storage device 10 to reduce the probability of generator 20 overload.

[0064] Since the maximum charging power of the energy storage device 10 is the maximum generating power of the generator 20 minus the power consumed by the load 50, and since both the energy storage device 10 and the load 50 are connected to the AC bus 30, the voltage at the connection port of the load 50 connected to the AC bus 30 is the same as the output voltage of the AC terminal. Therefore, in step S205, the power consumed by the load 50 can be determined based on the output voltage and load current, and then the maximum charging power of the energy storage device 10 can be determined based on the maximum generating power of the generator 20 and the power consumed by the load 50.

[0065] Step S206: Limit the reference current based on the maximum charging power to determine the target given current.

[0066] The target given current is used to represent the ideal value of the output current at the AC terminal of the bidirectional inverter circuit 13.

[0067] Since the charging power of the energy storage device 10 is positively correlated with the output current of the AC terminal, the maximum charging current can be determined based on the maximum charging power in step S206. The output current is then limited based on the maximum charging current, so that the absolute value of the target given current obtained after the limiting process is less than or equal to the absolute value of the maximum charging current, thereby reducing the probability of generator 20 overload.

[0068] Step S207: Generate a control signal based on the target given current and the output current. The control signal is used to adjust the output current of the AC terminal of the bidirectional inverter circuit.

[0069] In step S207, the output current deviation value can be determined based on the target given current and the output current, and then the current deviation value is adjusted based on a preset control loop to generate a control signal. The preset control loop may include at least one of a voltage loop, current loop, power loop, combined loop, or other control loops. This application does not limit the specific loop. The preset control loop may include one or more control loops / controllers, such as adders, subtractors, derivative controllers (D), proportional-integral (PI) controllers, proportional-integral-derivative (PI-DI) controllers, limiters, etc., and this application does not limit these.

[0070] The control signal can be, for example, a drive signal for driving the switching transistors on the bidirectional inverter circuit 13, such as a PWM (Pulse Width Modulation) signal. The control signal controls the switching logic and duty cycle of the switching transistors on the bidirectional inverter circuit 13, thereby adjusting the output current at the AC terminal of the bidirectional inverter circuit. In other embodiments, depending on the control method adopted, the control signal can also be other electrical signals or modulation parameters; this application does not limit the specific type of control signal.

[0071] It is understood that the control method for the energy storage device provided in this application, when the AC bus 30 is disconnected from the power grid 40, acquires the battery voltage of the battery pack 11, the load current of the load 50, the output voltage and current of the AC terminal, and the maximum power generation of the generator 20. Then, it adjusts the voltage deviation between the given DC bus voltage and the battery voltage to determine the reference current of the AC terminal. Since the power transmission direction is defined as positive when the energy storage device 10 discharges to the AC bus 30 and negative when the energy storage device 10 draws power from the AC bus 30, the energy storage device 10 is determined to be in charging mode when the reference current is less than 0. At this time, the power generation of the generator 20 is used to supply power to the energy storage device 10 and the load 50. Therefore, ideally, the maximum charging power of the energy storage device 10 is the maximum power generation of the generator 20 minus the power consumed by the load 50. Furthermore, since both the energy storage device 10 and the load 50 are connected to the AC bus 30, the voltage at the connection port of the load 50 to the AC bus 30 is the same as the output voltage of the AC terminal. Thus, the maximum charging power of the energy storage device 10 can be determined based on the maximum generating power, output voltage, and load current of the generator 20. The reference current is then limited based on the maximum charging power to determine the target current. Furthermore, a control signal is generated based on the target current and the output current to adjust the output current of the AC terminal of the bidirectional inverter circuit 13. This limits the output current of the AC terminal of the bidirectional inverter circuit 13, reducing the probability of the energy storage device 10 overloading and tripping due to excessive power draw from the AC bus 30. In summary, the control method for the energy storage device provided in this application effectively reduces the probability of the generator 20 overloading and tripping when the energy storage device 10 and the generator 20 are operating in parallel and the energy storage device 10 is in charging mode. Moreover, the control method for the energy storage device provided in this application allows the energy storage device 10 to operate in current source mode, resulting in better load current tracking characteristics and faster dynamic response speed. For example, the cutoff frequency of the current loop can reach 1kHz or higher, which facilitates rapid switching between charging and discharging modes of the energy storage device 10.

[0072] Please see Figure 3 In some embodiments, after performing step S203, the control method for the energy storage device further includes:

[0073] Step S301: When the reference current is greater than or equal to 0, determine that the energy storage device is in discharge mode.

[0074] It is understandable that since the polarity of the reference current is opposite to the polarity of the voltage deviation value, when the reference current is greater than or equal to 0, it means that the voltage deviation value is less than 0, and it can be determined that the energy storage device 10 is in the discharge mode.

[0075] Step S302: In discharge mode, determine the tracking coefficient based on the reference current and the proportional coefficient.

[0076] The proportional gain represents the proportional gain between the tracking coefficient and the reference current, and 0 < proportional gain ≤ 1. Thus, the tracking coefficient is positively correlated with the reference current.

[0077] In some embodiments, the product of the reference current and the proportional coefficient can be directly obtained as the tracking coefficient. In other embodiments, other algorithms can be used to determine the tracking coefficient based on the reference current and the proportional coefficient, for example, the value obtained after limiting the product of the reference current and the proportional coefficient can be used as the tracking coefficient. This application does not limit the specific value of the proportional coefficient, nor does it limit the specific algorithm for determining the tracking coefficient based on the reference current and the proportional coefficient in step S302.

[0078] Step S303: Determine the target given current based on the tracking coefficient and the load current; where 0 < tracking coefficient ≤ 1, and the tracking coefficient is positively correlated with the remaining energy of the battery pack.

[0079] After executing step S303, step S207 can be executed to generate a control signal based on the target given current and output current determined in step S303, so as to adjust the output current of the AC terminal of the bidirectional inverter circuit 13 to be close to or even equal to the target given current.

[0080] It is understandable that when the energy storage device 10 is in discharge mode, the more remaining energy the battery pack 11 has, the greater the discharge power, resulting in a larger reference current. Furthermore, since the tracking coefficient is positively correlated with the reference current, it is also positively correlated with the remaining energy of the battery pack.

[0081] In some embodiments, the product of the tracking coefficient and the load current can be calculated as the target given current. Since 0 < tracking coefficient ≤ 1, the target given current is positively correlated with the load current, and the target given current is less than or equal to the load current. Furthermore, since the tracking coefficient is positively correlated with the remaining energy of the battery pack, on the one hand, the more remaining energy the battery pack 11 has, the larger the tracking coefficient, making the target given current closer to the load current. Understandably, when the energy storage device 10 is in discharge mode, the energy storage device 10 and the generator 20 simultaneously supply power to the load 50. At this time, if the target given current is close to the load current, and the output current of the AC terminal of the bidirectional inverter circuit 13 is controlled according to the target given current, the energy storage device 10 can primarily supply power to the load 50. Even if more load 50 is suddenly added to the AC bus 30, the target given current can quickly track the current load current, thereby enabling the energy storage device 10 to supply power to the added load 50 in a timely manner. On the other hand, since the target current is positively correlated with the load current, when the load 50 is disconnected from the AC bus 30, or when the load power of the load 50 decreases and the load current decreases, the target current can decrease along with the load current. Thus, when the output current of the AC terminal is controlled according to the target current, the probability of the energy storage device 10 feeding into the generator 20 can be effectively reduced, thereby improving the safety of the generator 20.

[0082] In summary, by performing the above steps S301-S303, when the energy storage device 10 is in discharge mode, the output current of the AC terminal of the bidirectional inverter circuit 13 can be adjusted in a timely and flexible manner to supply power to the load 50, and the probability of the energy storage device 10 feeding current into the generator 20 can be effectively reduced, thereby improving the safety of the generator 20.

[0083] In some embodiments, before performing step S303, the control method for the energy storage device further includes:

[0084] The tracking coefficient is limited by a preset limiter to a range of 0 to 1.

[0085] In some embodiments, the tracking coefficient is limited by a preset limiter, including:

[0086] When the preset limiter determines that the tracking coefficient is less than 0, it outputs 0 as the tracking coefficient after limiting. When the preset limiter determines that the tracking coefficient is greater than 1, it outputs 1 as the tracking coefficient after limiting. When the preset limiter determines that the tracking coefficient is greater than or equal to 0 and less than or equal to 1, it uses the input tracking coefficient as the tracking coefficient after limiting. The tracking coefficient is related to the input energy. For example, if the battery or photovoltaic energy is sufficient, the tracking coefficient may reach 1; if the energy is insufficient, the tracking coefficient may be a smaller value. The tracking coefficient is determined by the PI output value of the preceding voltage loop.

[0087] Thus, by implementing the method provided in this embodiment, the tracking coefficient can be limited to the range of 0 to 1. Therefore, when the target given current is determined based on the tracking coefficient after the amplitude limiting process, the output current of the AC terminal of the bidirectional inverter circuit 13 can be adjusted in a timely and flexible manner to supply power to the load 50 when the energy storage device 10 is in the discharge mode. This effectively reduces the probability of the energy storage device 10 feeding current into the generator 20 and improves the safety of the generator 20.

[0088] Please see Figure 4 In some embodiments, step S205 includes the following steps S401-S402.

[0089] Step S401: Determine the load power based on the output voltage and load current.

[0090] In some embodiments, the product of the output voltage and the load current can be calculated as the load power. In other embodiments, to improve control accuracy, the effective value of the voltage can be calculated based on the output voltage and the effective value of the current can be calculated based on the load current, and then the product of the effective value of the voltage and the effective value of the current can be calculated as the load power.

[0091] This application does not limit the algorithm for determining the load power based on the output voltage and load current in step S401. For example, in other embodiments, the output voltage and load current may be filtered first, and then the load power may be determined based on the output voltage and load current.

[0092] Step S402: Determine the maximum charging power based on the maximum power generation and load power.

[0093] In some embodiments, the maximum power output of the generator 20 may be the rated power output of the generator 20.

[0094] In step S402, the difference between the maximum power generation and the load power can be calculated as the maximum charging power.

[0095] Thus, by executing steps S401-S402, the maximum charging power can be quickly and accurately determined in charging mode based on the maximum power generation, output voltage, and load current.

[0096] Please see Figure 5 In some embodiments, step S206 includes the following steps S501-S502.

[0097] Step S501: Determine the maximum charging current based on the maximum charging power and output voltage.

[0098] In some embodiments, the quotient obtained by dividing the maximum charging power by the output voltage can be directly calculated as the maximum charging current. In other embodiments, the quotient obtained by dividing the maximum charging power by the effective value of the output voltage can also be calculated, and then the product of the quotient and 1.414 can be obtained as the maximum charging current. This application does not limit the specific algorithm for determining the maximum charging current based on the maximum charging power and the output voltage in step S501.

[0099] Step S502: Limit the reference current based on the maximum charging current to determine the target given current.

[0100] It is understood that in this embodiment, since the power transmission direction when the energy storage device 10 draws power from the AC bus 30 is defined as reverse, the reference current indicating that the energy storage device 10 is in charging mode is negative. The maximum charging current obtained in step S501 is positive. Therefore, in step S502, the target given current should be determined by comparing the absolute value of the reference current with the maximum reference current.

[0101] Specifically, in some embodiments, the reference current is limited based on the maximum charging current to determine the target given current, including:

[0102] When the absolute value of the reference current is greater than the maximum charging current, the opposite of the maximum charging current is used as the target given current; when the absolute value of the reference current is less than the maximum charging current, the reference current is used as the target given current.

[0103] Thus, by executing steps S501-S502 provided in this embodiment, the reference current can be limited based on the maximum charging power to determine the target given current, so that when the energy storage device 10 is in charging mode, the output current of the AC terminal can be controlled according to the target given current to reduce the probability of overload tripping of the generator 20.

[0104] Please see Figure 6 In some embodiments, in order to improve the charging safety and charging efficiency of the energy storage device 10 during charging, it is also necessary to perform phase synchronization with the AC bus 30. In this case, step S502 includes the following steps S601-S603.

[0105] Step S601: Limit the reference current according to the maximum charging current to obtain the given current amplitude.

[0106] It is understood that, in this embodiment of the application, when the energy storage device 10 is in charging mode, the output current of the AC terminal is less than 0. Therefore, the negative of the maximum charging current determined in step S601 can be used as a lower limit value to limit the reference current.

[0107] For example, in some embodiments, step S601 includes:

[0108] When the absolute value of the reference current is less than or equal to the maximum charging current, the reference current is used as the given current amplitude.

[0109] When the absolute value of the reference current is greater than or equal to the maximum charging current, the maximum charging current is used as the given current amplitude.

[0110] Step S602: Phase-locked loop is applied to the AC bus voltage to obtain the synchronous phase angle of the AC bus voltage.

[0111] It is understandable that the energy storage device 10 is equipped with a phase-locked loop (PLL). Thus, the PLL can sample the AC bus voltage to determine the phase angle of the AC bus voltage as the synchronization phase angle. The specific working process of the PLL will not be elaborated here.

[0112] Step S603: Determine the target given current based on the synchronization phase angle and the given current amplitude.

[0113] For example, when the waveform of the AC bus voltage is a sine wave, the target given current can be calculated based on the following formula.

[0114] I ref =I am *cosφ

[0115] Among them, I ref Indicates the target given current; I am φ represents the given current amplitude; φ represents the synchronization phase angle.

[0116] In other embodiments, the target given current can also be calculated according to other formulas, and this application does not limit this.

[0117] Thus, by executing steps S601-S603, when adjusting the output current of the AC terminal according to the target given current, the target given current is synchronized using the sinusoidal quantity constructed by the generator 20, so that the output current is synchronized with the phase on the AC bus, thereby ensuring charging safety and improving charging efficiency.

[0118] Please see Figure 7 In some embodiments, step S207 includes the following steps S701-S704.

[0119] Step S701: Determine the current deviation value based on the target given current and the output current.

[0120] In some embodiments, the difference between the target given current and the output current can be directly calculated as the current deviation value.

[0121] Step S702: Adjust the current deviation value to determine the voltage adjustment amount.

[0122] The algorithm used for deviation adjustment can be a PI (Proportional Integral Control) algorithm, a PID (Proportional Integration Differentiation Control) algorithm, or other adjustment algorithms. This application does not limit the deviation adjustment algorithm used in step S702.

[0123] Step S703: Determine the modulation voltage based on the voltage adjustment amount and the output voltage.

[0124] In some embodiments, the sum of the voltage regulation amount and the output voltage can be calculated as the modulation voltage. In other embodiments, the fundamental component can be calculated based on the output voltage, and then the sum of the voltage regulation amount and the substrate component can be calculated as the modulation voltage. In other embodiments, when the AC terminal AC includes multi-phase AC voltage, the phase voltage of each phase can be determined based on the output voltage of the AC terminal AC, and then the sum of the voltage regulation amount and the phase voltage can be calculated as the modulation voltage.

[0125] Step S704: Generate a control signal based on the modulation voltage.

[0126] It is understood that in step S704, the modulation voltage can modulate the carrier wave to generate a control signal. This application does not limit the modulation algorithm used when modulating the modulation voltage.

[0127] Thus, after determining the target current for the energy storage device 10 in charging or discharging mode, control signals can be generated by executing steps S701-S704 to flexibly and quickly adjust the output current of the AC terminal. This reduces the probability of overload tripping of the generator 20 when the energy storage device 10 is in charging mode, and reduces the probability of current injection into the generator 20 when the energy storage device 10 is in discharging mode, thereby improving the safety of generator 20.

[0128] Please refer to the following: Figure 1 and Figure 8, Figure 8 This paper illustrates a specific control block diagram of a control method for an energy storage device provided in an embodiment of this application.

[0129] First, the first subtractor 101 calculates the voltage deviation value Udev based on the given DC bus voltage Ubusref and battery voltage Vbus. Then, the first PI regulator 102 adjusts the voltage deviation value Udev to obtain the reference current Iref_1. The first limiter 103 performs preliminary limiting processing on the reference current Iref_1 to obtain the limited reference current Iref_2, thereby reducing the probability of subsequent overshoot. Next, the judge 104 determines the polarity of the limited reference current Iref_2. Specifically, when the limited reference current Iref_2 is less than 0, it is confirmed that the energy storage device 10 is in charging mode. At this time, the charging loop is entered, and the target given current Itarg1 output by the discharging loop is controlled to be 0. After entering the charging loop, the second limiter 105 limits the reference current Iref_2 based on the upper limit value 0 and the lower limit value Ich_m to obtain the given current amplitude Iamp, where the given current amplitude Iamp is less than or equal to 0 and greater than or equal to the lower limit value Ich_m. Then, the first multiplier 106 calculates the target given current Itarg2 obtained from the charging loop based on the given current amplitude Iamp and the AC bus phase Cosφ. Thus, the first adder 107 determines the target given current Itarget of the AC terminal AC based on the target given current Itarg2 obtained from the charging loop and the target given current Itarg1 output from the discharging loop. Next, the second subtractor 108 calculates the current deviation value Idev based on the target current Itarget and the output current Iout of the AC terminal. Then, the second PI regulator 109 adjusts the current deviation value Idev to obtain the voltage regulation amount Ureg. Finally, the second adder 110 calculates the modulation voltage Um based on the voltage regulation amount Ureg and the fundamental component Ualpha of the output voltage.

[0130] The lower limit value Ich_m and the AC bus phase Cosφ in the charging loop can be obtained based on the following loop.

[0131] Specifically, the current RMS calculator 111 calculates the load current RMS value Irms based on the load current Iload, and the voltage RMS calculator 112 calculates the output voltage RMS value Urms based on the AC output voltage Uac. Then, the second multiplier 113 calculates the load power P1oad based on the load current RMS value Irms and the output voltage RMS value Urms. Next, the third subtractor 114 calculates the maximum charging power Pch_m based on the generator 20's maximum generating power Pmax and the load power P1oad. Then, the divider 115 calculates the given current amplitude Ich_ref based on the maximum charging power Pch_m and the output voltage RMS value Urms. Finally, the third multiplier 116 calculates the given current peak value as the lower limit value Ich_m based on the given current amplitude Ich_ref and 1.414.

[0132] Meanwhile, the phase-locked loop 117 locks the output voltage Uac of the AC terminal AC to obtain the synchronous phase angle φ, and then the phase calculator 118 calculates the AC bus phase Cosφ based on the synchronous phase angle φ.

[0133] Furthermore, in Figure 8 In the control block diagram shown, when the judge 104 determines that the reference current Iref_2 after the limiting process is greater than 0, it enters the discharge loop, while the target given current Itarg2 obtained by the charging loop is 0. In the discharge loop, the coefficient calculator 119 calculates the tracking coefficient Ftrac1 based on the reference current Iref_2 after the limiting process and its own proportional coefficient 1 / K. Further, the third limiter 120 limits the tracking coefficient Ftrac1, making the resulting tracking coefficient Ftrac2 greater than or equal to 0 and less than or equal to 1. Then, the fourth multiplier 121 calculates the target given current Itarg1 of the discharge loop based on the tracking coefficient Ftrac2 obtained after the limiting process and the load current Iload. It can be understood that after calculating the target given current Itarg1 of the discharge loop, the first adder 107, the second subtractor 108, the second PI regulator 109, and the second adder 110 sequentially perform their respective calculations, as detailed above.

[0134] It is understandable that the above control block diagram, by constructing charging and discharging loops, enables flexible switching between charging and discharging modes for the energy storage device 10, reducing algorithm complexity. Specifically, in the discharging loop, a target current is generated by tracking the load current, allowing the energy storage device 10 and generator 20 to share the load current. This enables transient waveform allocation, improving transient and dynamic performance. Furthermore, because the tracking coefficient makes the target current positively correlated with the load current, the target current decays as the load current decays, reducing the probability of generator 20 being overloaded. In the charging loop, the maximum charging power of the energy storage device 10 is determined by the maximum generating power of generator 20 and the load current. The reference current is then limited using the maximum charging power to obtain the target current, thereby reducing the probability of overload tripping when generator 20 simultaneously supplies power to load 50 and energy storage device 10. Moreover, since the above control block diagram uses a current loop, the entire control loop has a fast response speed. For example, the cutoff frequency of the current loop can reach 1KHz or higher, which can complete the switching between charging and discharging modes in a short time. For example, the charging and discharging conversion time can be less than 20ms.

[0135] Understandably, Figure 8 The control process shown in the control block diagram can be implemented by the control method of the energy storage device provided in this application, for example by the computer program stored in the controller 14. Specific implementation details will not be elaborated here.

[0136] Understandably, the above control block diagram uses the bidirectional inverter circuit 13 as an example of a single-phase inverter circuit to illustrate the operation of the control method for the energy storage device. In other embodiments, when the bidirectional inverter circuit 13 is a multi-phase inverter circuit, the control block diagram used is the same as... Figure 8 The control block diagrams are roughly the same, the main difference being that each phase in a multiphase inverter circuit can use a similar approach. Figure 8 The control block diagram yields the modulation voltage for each phase, or a multi-phase inverter circuit can also obtain the modulation voltage for each phase. Figure 8 The output voltage Uac is replaced sequentially with the d-axis output voltage and the q-axis output voltage, and then based on... Figure 8 A similar control block diagram calculates the d-axis modulation voltage and q-axis modulation voltage corresponding to the d-axis output voltage and q-axis output voltage, respectively. Then, the reference modulation parameters corresponding to each phase are calculated by the 3S / 2R coordinate transformer to generate the control signal corresponding to each phase. The specific control block diagram will not be described in detail here.

[0137] Please refer to it again. Figure 1One embodiment of this application also provides an energy storage device 10, including a battery pack 11, a DC bus 12, a bidirectional inverter circuit 13, and a controller 14. The DC terminal (DC) of the bidirectional inverter circuit 13 is connected to the battery pack 11 via the DC bus 12, and the AC terminal (AC) of the bidirectional inverter circuit 13 is connected to an AC bus 30. The AC bus 30 is also used to connect a generator 20, a power grid 40, and a load 50. The controller 14 is used to execute the control method of the energy storage device as described in any of the above embodiments.

[0138] Please refer to it again. Figure 1 One embodiment of this application also provides a power supply system 100, including a generator 20 and an energy storage device 10. Both the generator 20 and the energy storage device 10 are connected to an AC bus 30, which is also used to connect a load 50.

[0139] Please continue reading. Figure 9 An embodiment of this application also provides an electronic device 200, including a memory 201 and a processor 202. The processor 202 is used to execute a computer program stored in the memory 201 to implement the control method executed by the energy storage device as described in any of the above embodiments. It is understood that in some embodiments, the electronic device 200 may be integrated into the energy storage device 10, while in other embodiments, the electronic device 200 may be independently configured.

[0140] The processor 202 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0141] Memory 201 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed discs, laser discs, optical discs, digital universal discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. Memory 420 may exist independently and be connected to processor 202 via a bus. Memory 201 may also be integrated with processor 202.

[0142] Please continue reading. Figure 10 One embodiment of this application also provides a computer-readable storage medium 300 storing a computer program 301 thereon. When executed by a processor 202, the computer program 301 implements the control method for the energy storage device as described in the above technical solutions. The computer-readable storage medium may be a portable compact disc read-only memory (CD-ROM) and include program code, and can run on a terminal device, such as a personal computer. However, the program product of the present invention is not limited thereto. In this document, the readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0143] The above-described program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0144] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0145] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0146] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0147] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0148] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for an energy storage device, the energy storage device comprising a battery pack, a DC bus, and a bidirectional inverter circuit, characterized in that, The DC terminal of the bidirectional inverter circuit is connected to the battery pack via the DC bus, and the AC terminal of the bidirectional inverter circuit is connected to the AC bus. The AC bus is also used to connect the generator, the power grid, and the load. The method includes: When the AC bus is disconnected from the power grid, the battery voltage of the battery pack, the load current of the load, the output voltage of the AC terminal, the output current of the AC terminal, and the maximum power generation of the generator are obtained. Obtain the voltage deviation value between the given DC bus voltage and the battery voltage; The voltage deviation value is adjusted to determine the reference current; When the reference current is less than 0, the energy storage device is determined to be in charging mode; In the charging mode, the maximum charging power is determined based on the maximum power generation, the output voltage, and the load current; The reference current is limited based on the maximum charging power to determine the target given current. A control signal is generated based on the target given current and the output current, and the control signal is used to adjust the output current of the AC terminal of the bidirectional inverter circuit.

2. The control method according to claim 1, characterized in that, The method further includes: When the reference current is greater than or equal to 0, the energy storage device is determined to be in discharge mode; In the discharge mode, the tracking coefficient is determined based on the reference current and the proportional coefficient; The target given current is determined based on the tracking coefficient and the load current; Wherein, 0 < tracking coefficient ≤ 1, and the tracking coefficient is positively correlated with the remaining energy of the battery pack.

3. The control method according to claim 2, characterized in that, Before determining the target given current based on the tracking coefficient and the load current, the method further includes: The tracking coefficient is limited to the range of 0 to 1 by using a preset limiter.

4. The control method according to claim 1, characterized in that, Determining the maximum charging power based on the maximum power generation, the output voltage, and the load current includes: The load power is determined based on the output voltage and the load current. The maximum charging power is determined based on the maximum power generation and the load power.

5. The control method according to claim 1, characterized in that, The step of limiting the reference current based on the maximum charging power to determine the target given current includes: The maximum charging current is determined based on the maximum charging power and the output voltage; The reference current is limited based on the maximum charging current to determine the target given current.

6. The control method according to claim 3, characterized in that, The step of limiting the reference current based on the maximum charging current to determine the target given current includes: The reference current is limited based on the maximum charging current to obtain a given current amplitude. Phase-locked loop is applied to the AC bus voltage to obtain the synchronous phase angle of the AC bus voltage; The target given current is determined based on the synchronization phase angle and the given current amplitude.

7. The control method according to claim 6, characterized in that, The step of limiting the reference current based on the maximum charging current to obtain a given current amplitude includes: When the absolute value of the reference current is less than or equal to the maximum charging current, the reference current is used as the given current amplitude. When the absolute value of the reference current is greater than or equal to the maximum charging current, the maximum charging current is used as the given current amplitude.

8. The control method according to claim 1, characterized in that, The step of generating a control signal based on the target given current and the output current includes: The current deviation value is determined based on the target given current and the output current; The current deviation value is adjusted to determine the voltage adjustment amount; The modulation voltage is determined based on the voltage adjustment amount and the output voltage; The control signal is generated based on the modulation voltage.

9. An energy storage device, comprising a battery pack, a DC bus, a bidirectional inverter circuit, and a controller, characterized in that, The DC terminal of the bidirectional inverter circuit is connected to the battery pack via the DC bus, and the AC terminal of the bidirectional inverter circuit is connected to the AC bus. The AC bus is also used to connect the generator, the power grid, and the load. The controller is used to execute the control method of the energy storage device as described in any one of claims 1 to 8.

10. A power supply system, characterized in that, The power supply system includes a generator and an energy storage device as described in claim 9, wherein both the generator and the energy storage device are connected to an AC bus, and the AC bus is also used to connect a load.

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