Shutdown method, system, equipment and medium for off-grid multi-unit parallel energy storage system

Abstract

The present invention discloses a shutdown method, system, device, and storage medium for an off-grid multi-unit parallel energy storage system. The system includes an energy management system and multiple parallel energy storage subsystems, wherein the energy management system is electrically connected to each energy storage subsystem. The energy management system determines a preset waiting time based on the number of energy storage subsystems and the energy management system's instruction issuance cycle. The preset waiting time and shutdown instruction are issued to each energy storage subsystem at each interval of the instruction issuance cycle. After receiving the shutdown instruction issued by the energy management system, the energy storage subsystem sets the energy storage subsystem to a pre-shutdown mode. The system determines whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time. If the pre-shutdown time reaches the preset waiting time, the energy storage subsystem is shut down. Thus, without changing the hardware connection or adding a hardware synchronization signal, the technical advantages of droop control are guaranteed and the off-grid multi-unit parallel energy storage system can be shut down safely without triggering overload protection.

Description

Technical Field

[0001] The present invention relates to the field of power management, and in particular to a shutdown method, system, device and computer-readable storage medium for an off-grid multi-unit parallel energy storage system. Background Art

[0002] like Figure 3 As shown in the topology diagram for multi-unit parallel operation, ESS (energy storage system) applications require off-grid functionality for backup power, microgrids, and black start. To meet customer capacity requirements, multiple units are often connected in parallel for off-grid and parallel operation. Traditional off-grid control modes primarily include voltage-frequency (VF) and droop modes.

[0003] Because VF mode parallel operation requires CAN (Controller Area Network) communication and master-slave control, droop mode offers a technical advantage in multi-system parallel operation in practical engineering applications. In a multi-unit parallel system operating in droop mode, each subsystem automatically shares power based on AC voltage and frequency, eliminating the need for communication connections or master-slave distinctions. This allows for more flexible system layout and simpler, more reliable control.

[0004] However, when the system is operating in parallel or off-grid mode with load, if system shutdown is required for certain reasons (such as switching between on-grid and off-grid modes or maintenance), the inconsistency in the EMS (energy management system)'s communication command delays for each subsystem and the internal communication time between the ARM (Advanced RISC Machines) and the DSP (Digital Signal Processor) within the PCS (Power Conversion System) can lead to a sequential shutdown of the PCSs during the actual parallel system shutdown process. The load power of the first PCS to shut down is transferred to the later PCS. If the load is heavy at this time, the later PCS may trigger overload protection, affecting customer service. Frequent overload protection may also damage PCS fuses, modules, or the battery system, threatening system safety. Traditional solutions consider adding corresponding synchronization signals between the PCSs of different subsystems to ensure synchronized shutdown. This solution increases hardware cost and system complexity, and negates the technical advantage of droop control without communication interconnects. Summary of the Invention

[0005] The main purpose of the present invention is to provide a shutdown method for an off-grid multi-unit parallel energy storage system, aiming to solve the technical problem in the prior art of how to safely shut down an off-grid multi-unit parallel energy storage system while ensuring the technical advantages of droop control.

[0006] To achieve the above objectives, the present invention provides a shutdown method for an off-grid multi-unit parallel energy storage system, which is applied to an energy storage subsystem. The off-grid multi-unit parallel energy storage system includes multiple parallel energy storage subsystems. The shutdown method for the off-grid multi-unit parallel energy storage system includes:

[0007] After receiving the shutdown command from the energy management system, the energy storage subsystem is set to pre-shutdown mode;

[0008] Determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time;

[0009] If the pre-shutdown time reaches the preset waiting time, the energy storage subsystem is shut down.

[0010] Optionally, before the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time, the method further includes:

[0011] Determining whether the energy storage subsystem meets the triggering conditions for early shutdown;

[0012] If the conditions are met, the step of shutting down the energy storage subsystem is executed;

[0013] If not, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time is performed.

[0014] Optionally, the step of determining whether the energy storage subsystem meets the triggering condition for early shutdown includes:

[0015] Determining whether the AC current of the energy storage converter of the energy storage subsystem exceeds the rated value;

[0016] If the AC current exceeds the rated value, it is determined that the energy storage subsystem meets the triggering condition for early shutdown;

[0017] If the AC current does not exceed the rated value, it is determined that the energy storage subsystem does not meet the triggering condition for early shutdown.

[0018] Optionally, after the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time, the method further includes:

[0019] If the pre-shutdown time does not reach the preset waiting time, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time is performed.

[0020] Optionally, it is applied to an energy management system, wherein the off-grid multi-unit parallel energy storage system includes a plurality of parallel energy storage subsystems, and the energy management system is electrically connected to each of the energy storage subsystems; the shutdown method of the off-grid multi-unit parallel energy storage system includes:

[0021] Determining a preset waiting time according to the number of the energy storage subsystems and the instruction issuing cycle of the energy management system;

[0022] At each interval of the instruction issuance cycle, the preset waiting time and shutdown instruction are issued to each of the energy storage subsystems; so that the energy storage subsystem is set to the pre-shutdown mode after receiving the shutdown instruction, and the energy storage subsystem is shut down when the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time.

[0023] Optionally, after the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, the method further includes:

[0024] Obtaining the power output of the energy storage subsystem and the load power demand;

[0025] Determine whether the power output of the remaining energy storage subsystems can meet the load power requirements after one or more energy storage subsystems are shut down;

[0026] If so, an early shutdown instruction is issued to the one or more energy storage subsystems, so that the one or more energy storage subsystems meet the triggering conditions for early shutdown.

[0027] Optionally, after the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, the method further includes:

[0028] receiving a first duration of waiting to receive the shutdown command and a second duration of internally transmitting the shutdown command, uploaded by each energy storage subsystem;

[0029] The preset waiting time is adjusted according to the first time and the second time to generate a new preset waiting time.

[0030] Optionally, the step of adjusting the preset waiting time according to the first time and the second time includes:

[0031] A maximum time difference is determined according to the largest first time length and the largest second time length, and the preset waiting time length is adjusted to be greater than the maximum time difference, so as to generate a new preset waiting time length.

[0032] Optionally, the shutdown method of the off-grid multi-unit parallel energy storage system further includes:

[0033] Setting the energy storage subsystem to a pre-shutdown mode according to the time sequence of issuing the shutdown instructions;

[0034] After the maximum time difference has elapsed since the shutdown instruction was issued, all the energy storage subsystems are set to a pre-shutdown mode;

[0035] After the shutdown instruction is issued, all the energy storage subsystems are shut down after the maximum time difference and the preset waiting time period during which the energy storage subsystem is in the pre-shutdown mode have passed.

[0036] Optionally, after the step of setting the energy storage subsystem to the pre-shutdown mode according to the time sequence of issuing the shutdown instructions, the method further includes:

[0037] After the first energy storage subsystem that receives the shutdown instruction has waited twice as long as the preset waiting time, all energy storage subsystems are shut down.

[0038] To achieve the above object, the present invention provides an off-grid multi-unit parallel energy storage system, the off-grid multi-unit parallel energy storage system comprising an energy management system and a plurality of parallel energy storage subsystems, the energy management system being electrically connected to each of the energy storage subsystems;

[0039] The energy management system determines a preset waiting time according to the number of the energy storage subsystems and the instruction issuing cycle of the energy management system;

[0040] The energy management system issues the preset waiting time and shutdown instruction to each of the energy storage subsystems at intervals of the instruction issuance cycle;

[0041] After receiving the shutdown instruction issued by the energy management system, the energy storage subsystem sets the energy storage subsystem to a pre-shutdown mode;

[0042] The energy storage subsystem determines whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time; if the pre-shutdown time reaches the preset waiting time, the energy storage subsystem is shut down.

[0043] Optionally, the energy management system obtains the power output of the energy storage subsystem and the load power demand;

[0044] Determine whether the power output of the remaining energy storage subsystems can meet the load power requirements after one or more energy storage subsystems are shut down;

[0045] If so, an early shutdown instruction is issued to the one or more energy storage subsystems, so that the one or more energy storage subsystems meet the triggering conditions for early shutdown.

[0046] Optionally, the energy management system receives a first duration of waiting to receive the shutdown instruction and a second duration of internally transmitting the shutdown instruction uploaded by each energy storage subsystem;

[0047] The preset waiting time is adjusted according to the first time and the second time to generate a new preset waiting time.

[0048] Optionally, the energy management system determines a maximum time difference according to the maximum first time length and the maximum second time length, and adjusts the preset waiting time length to be greater than the maximum time difference, so as to generate a new preset waiting time length.

[0049] Optionally, the energy management system sets the energy storage subsystem to a pre-shutdown mode according to a time sequence of issuing the shutdown instructions;

[0050] After the maximum time difference has elapsed since the shutdown instruction was issued, all the energy storage subsystems are set to a pre-shutdown mode;

[0051] After the shutdown instruction is issued, all the energy storage subsystems are shut down after the maximum time difference and the preset waiting time period during which the energy storage subsystem is in the pre-shutdown mode have passed.

[0052] Optionally, the energy management system shuts down all the energy storage subsystems after the first energy storage subsystem to receive the shutdown instruction has waited twice as long as the preset waiting time.

[0053] Optionally, the energy storage subsystem determines whether the energy storage subsystem meets a triggering condition for early shutdown;

[0054] If the conditions are met, the step of shutting down the energy storage subsystem is executed;

[0055] If not, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time is performed.

[0056] Optionally, the energy storage subsystem determines whether the AC current of the energy storage converter of the energy storage subsystem exceeds a rated value;

[0057] If the AC current exceeds the rated value, it is determined that the energy storage subsystem meets the triggering condition for early shutdown;

[0058] If the AC current does not exceed the rated value, it is determined that the energy storage subsystem does not meet the triggering condition for early shutdown.

[0059] Optionally, if the pre-shutdown time of the energy storage subsystem does not reach the preset waiting time, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time is executed.

[0060] In addition, to achieve the above-mentioned purpose, the present invention also provides a shutdown device for an off-grid multi-unit parallel energy storage system, wherein the shutdown device for the off-grid multi-unit parallel energy storage system comprises: a memory, a processor, and a shutdown program for the off-grid multi-unit parallel energy storage system stored in the memory and executable on the processor. When the shutdown program for the off-grid multi-unit parallel energy storage system is executed by the processor, the steps of the shutdown method for the off-grid multi-unit parallel energy storage system as described above are implemented.

[0061] In addition, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, on which a shutdown program of an off-grid multi-unit parallel energy storage system is stored. When the shutdown program of the off-grid multi-unit parallel energy storage system is executed by a processor, the steps of the shutdown method of the off-grid multi-unit parallel energy storage system as described above are implemented.

[0062] Embodiments of the present invention propose a shutdown method, device, and computer-readable storage medium for an off-grid multi-unit parallel energy storage system. Upon receiving a shutdown command from the energy management system (EMS), the digital signal processor (DSP) of the energy storage converter (PCS) immediately enters a pre-shutdown mode. If the pre-shutdown duration in pre-shutdown mode reaches a preset waiting time (ΔT), the DSP of the PCS shuts down. Furthermore, within the preset waiting time (ΔT), if the AC current of the PCS of a particular energy storage subsystem (ESS) exceeds the rated value, the DSP is triggered to shut down in advance. Theoretically, within 2ΔT after the first PCS enters pre-shutdown mode, all subsystems should be shut down without triggering overload protection. This ensures the technical advantages of droop control and enables safe shutdown of the off-grid multi-unit parallel energy storage system without changing hardware connections or adding hardware synchronization signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a schematic diagram of the structure of the operating equipment of the hardware operating environment involved in the embodiment of the present invention;

[0064] Figure 2 This is a flow chart of a first embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention;

[0065] Figure 3 This is a flow chart of a second embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention;

[0066] Figure 4 This is a flow chart of a third embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention;

[0067] Figure 5 This is a flow chart of a fourth embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention;

[0068] Figure 6 This is a flow chart of a fifth embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention;

[0069] Figure 7 This is a flow chart of a sixth embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention;

[0070] Figure 8 A schematic diagram of the topological relationship of parallel operation of multiple units in an embodiment of a shutdown method for an off-grid multiple-unit parallel energy storage system according to the present invention;

[0071] Figure 9 A schematic diagram of system communication delay for an embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention;

[0072] Figure 10 A schematic diagram of the shutdown control logic flow of an energy storage system ESS according to an embodiment of a shutdown method of an off-grid multi-unit parallel energy storage system of the present invention;

[0073] Figure 11 Schematic diagram of the system shutdown timeline of an embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention.

[0074] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0075] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0076] Reference Figure 1 , Figure 1 This is a schematic diagram of the structure of the operating equipment of the hardware operating environment involved in the embodiment of the present invention.

[0077] like Figure 1As shown, the operating device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a network interface 1003, and a memory 1004. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The network interface 1003 may optionally include a standard wired interface, a wireless interface (such as a wireless fidelity (WIreless-FIdelity, WI-FI) interface). The memory 1004 may be a high-speed random access memory (Random Access Memory, RAM) memory, or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk memory. The memory 1004 may optionally also be a storage device independent of the aforementioned processor 1001.

[0078] Those skilled in the art will understand that Figure 1 The structure shown in the figure does not constitute a limitation on the operating device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0079] like Figure 1 As shown, the memory 1004 as a storage medium may include an operating system, a data storage module, a network communication module, a user interface module, and a shutdown program of an off-grid multi-unit parallel energy storage system.

[0080] exist Figure 1 In the operating device shown, the network interface 1003 is mainly used for data communication with other devices; the processor 1001 and the memory 1004 in the operating device of the present invention can be set in the operating device, and the operating device calls the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004 through the processor 1001 and performs the following operations:

[0081] It is applied to the energy storage subsystem. The off-grid multi-unit parallel energy storage system includes multiple parallel energy storage subsystems.

[0082] The shutdown method of the off-grid multi-unit parallel energy storage system comprises the following steps:

[0083] After receiving the shutdown command from the energy management system, the energy storage subsystem is set to pre-shutdown mode;

[0084] Determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time;

[0085] If the pre-shutdown time reaches the preset waiting time, the energy storage subsystem is shut down.

[0086] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0087] Before the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time, the method further includes:

[0088] Determining whether the energy storage subsystem meets the triggering conditions for early shutdown;

[0089] If the conditions are met, the step of shutting down the energy storage subsystem is executed;

[0090] If not, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time is performed.

[0091] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0092] The step of determining whether the energy storage subsystem meets the triggering condition for early shutdown includes:

[0093] Determining whether the AC current of the energy storage converter of the energy storage subsystem exceeds the rated value;

[0094] If the AC current exceeds the rated value, it is determined that the energy storage subsystem meets the triggering condition for early shutdown;

[0095] If the AC current does not exceed the rated value, it is determined that the energy storage subsystem does not meet the triggering condition for early shutdown.

[0096] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0097] After the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time, the method further includes:

[0098] If the pre-shutdown time does not reach the preset waiting time, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time is performed.

[0099] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0100] It is applied to an energy management system, wherein the off-grid multi-unit parallel energy storage system includes a plurality of parallel energy storage subsystems, and the energy management system is electrically connected to each of the energy storage subsystems; the shutdown method of the off-grid multi-unit parallel energy storage system includes:

[0101] Determining a preset waiting time according to the number of the energy storage subsystems and the instruction issuing cycle of the energy management system;

[0102] At each interval of the instruction issuance cycle, the preset waiting time and shutdown instruction are issued to each of the energy storage subsystems; so that the energy storage subsystem is set to the pre-shutdown mode after receiving the shutdown instruction, and the energy storage subsystem is shut down when the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time.

[0103] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0104] After the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, the method further includes:

[0105] Obtaining the power output of the energy storage subsystem and the load power demand;

[0106] Determine whether the power output of the remaining energy storage subsystems can meet the load power requirements after one or more energy storage subsystems are shut down;

[0107] If so, an early shutdown instruction is issued to the one or more energy storage subsystems, so that the one or more energy storage subsystems meet the triggering conditions for early shutdown.

[0108] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0109] After the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, the method further includes:

[0110] receiving a first duration of waiting to receive the shutdown command and a second duration of internally transmitting the shutdown command, uploaded by each energy storage subsystem;

[0111] The preset waiting time is adjusted according to the first time and the second time to generate a new preset waiting time.

[0112] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0113] The step of adjusting the preset waiting time according to the first time and the second time comprises:

[0114] A maximum time difference is determined according to the largest first time length and the largest second time length, and the preset waiting time length is adjusted to be greater than the maximum time difference, so as to generate a new preset waiting time length.

[0115] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0116] The shutdown method of the off-grid multi-unit parallel energy storage system further includes:

[0117] Setting the energy storage subsystem to a pre-shutdown mode according to the time sequence of issuing the shutdown instructions;

[0118] After the maximum time difference has elapsed since the shutdown instruction was issued, all the energy storage subsystems are set to a pre-shutdown mode;

[0119] After the shutdown instruction is issued, all the energy storage subsystems are shut down after the maximum time difference and the preset waiting time period during which the energy storage subsystem is in the pre-shutdown mode have passed.

[0120] Furthermore, the processor 1001 may call the shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory 1004, and further perform the following operations:

[0121] After the step of setting the energy storage subsystem to the pre-shutdown mode according to the time sequence of issuing the shutdown instructions, the method further includes:

[0122] After the first energy storage subsystem that receives the shutdown instruction has waited twice as long as the preset waiting time, all energy storage subsystems are shut down.

[0123] The embodiment of the present invention provides a shutdown method for an off-grid multi-unit parallel energy storage system, referring to Figure 2 , Figure 2 This is a flow chart of a first embodiment of a shutdown method for an off-grid multi-unit parallel energy storage system according to the present invention.

[0124] In this embodiment, it is applied to an energy storage subsystem. The off-grid multi-unit parallel energy storage system includes multiple parallel energy storage subsystems. The shutdown method of the off-grid multi-unit parallel energy storage system includes:

[0125] Step S10: After receiving the shutdown instruction issued by the energy management system, the energy storage subsystem is set to a pre-shutdown mode.

[0126] When an off-grid multi-unit parallel energy storage system is operating in parallel or off-grid with load, and certain factors (such as switching between on-grid and off-grid modes or maintenance) require system shutdown, the digital signal processor (DSP) of the energy storage converter (PCS) in the energy storage subsystem (ESS) receives a shutdown command from the energy management system (EMS) to each ESS. During normal operation, the ESS determines whether it has received a shutdown command from the EMS. Upon confirming receipt of the EMS shutdown command, it switches from operating mode to pre-shutdown mode.

[0127] Step S20: determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time.

[0128] like Figure 8 As shown in the diagram of the multi-unit parallel operation topology, the off-grid multi-unit parallel energy storage system includes multiple parallel energy storage subsystems (ESS1, ESS2, ..., ESSn). When an ESS is operating normally, if the digital signal processor (DSP) of its PCS receives a shutdown command from the EMS, it immediately enters pre-shutdown mode. Specifically, upon receiving a shutdown command from the EMS, an ESS immediately enters pre-shutdown mode instead of shutting down immediately. This prevents the load power from the PCS that shuts down first from being transferred to the later PCS, potentially triggering overload protection and system safety issues. After receiving the shutdown command from the EMS and switching to pre-shutdown mode, the ESS then determines whether the pre-shutdown duration in pre-shutdown mode has reached a preset waiting time, ΔT.

[0129] Step S30: If the pre-shutdown time reaches the preset waiting time, shutting down the energy storage subsystem.

[0130] If the energy storage subsystem ESS is in the pre-shutdown mode for a period longer than the preset waiting time ΔT after receiving the shutdown command from the energy management system EMS, it indicates that the energy storage subsystem ESS can be switched from the pre-shutdown mode to the shutdown mode. After switching to the shutdown mode, the digital signal processor DSP of the energy storage converter PCS of the energy storage subsystem ESS is shut down.

[0131] In this embodiment, the digital signal processor (DSP) of the energy storage converter (PCS) immediately enters pre-shutdown mode upon receiving a shutdown command from the energy management system (EMS). If the pre-shutdown duration in pre-shutdown mode reaches a preset waiting time (ΔT), the digital signal processor (DSP) of the PCS shuts down. Theoretically, within 2ΔT of the first energy storage converter (PCS) entering pre-shutdown mode, all energy storage subsystems (ESS) will have completed shutdown without triggering overload protection. This ensures the technical advantages of droop control while enabling safe shutdown of off-grid multi-unit parallel energy storage systems without changing hardware connections or adding hardware synchronization signals.

[0132] Optionally, refer to Figure 3 The flowchart of the second embodiment, before the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time, further includes:

[0133] Step S40: determining whether the energy storage subsystem meets the triggering conditions for early shutdown;

[0134] If the conditions are met, the step of shutting down the energy storage subsystem is executed;

[0135] If not, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time is performed.

[0136] In this embodiment, after receiving a shutdown command from the energy management system (EMS) and switching the energy storage subsystem (ESS) to a pre-shutdown mode, before determining whether the pre-shutdown duration in the pre-shutdown mode has reached a preset waiting time ΔT, that is, while the energy storage subsystem (ESS) is in the pre-shutdown mode, it is determined whether the energy storage subsystem (ESS) meets the triggering conditions for premature shutdown. If so, the energy storage subsystem (ESS) is shut down. If not, it is determined whether the duration of the energy storage subsystem (ESS) in the pre-shutdown mode exceeds the preset shutdown duration. Pre-shutdown triggering conditions include, but are not limited to, the AC current of the energy storage converter (PCS) exceeding the rated value within the preset shutdown duration, or receiving a premature shutdown command from the energy management system (EMS) based on the power output of each energy storage subsystem (ESS) and the load power demand.

[0137] Optionally, the step of determining whether the energy storage subsystem meets the triggering condition for early shutdown includes:

[0138] Determining whether the AC current of the energy storage converter of the energy storage subsystem exceeds the rated value;

[0139] If the AC current exceeds the rated value, it is determined that the energy storage subsystem meets the triggering condition for early shutdown;

[0140] If the AC current does not exceed the rated value, it is determined that the energy storage subsystem does not meet the triggering condition for early shutdown.

[0141] In this embodiment, after receiving a shutdown command from the energy management system (EMS) and switching the energy storage subsystem (ESS) to pre-shutdown mode, before determining whether the pre-shutdown duration in pre-shutdown mode has reached a preset waiting time ΔT, that is, while the energy storage subsystem (ESS) is in pre-shutdown mode, a determination is made as to whether the AC current of the energy storage converter (PCS) of the ESS exceeds a rated value. If so, the ESS is shut down. If not, a determination is made as to whether the duration of the ESS in pre-shutdown mode exceeds a preset shutdown duration. Specifically, if the duration of the ESS in pre-shutdown mode exceeds the preset shutdown duration, or if the AC current of the energy storage converter (PCS) exceeds the rated value within the preset shutdown duration, the ESS is shut down.

[0142] Optionally, after the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time, the method further includes:

[0143] If the pre-shutdown time does not reach the preset waiting time, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time is performed.

[0144] In this embodiment, after receiving a shutdown command from the energy management system (EMS) and switching the energy storage subsystem (ESS) to a pre-shutdown mode, if the pre-shutdown duration in the pre-shutdown mode has not reached a preset waiting time ΔT, the system then continues to determine whether the pre-shutdown duration in the pre-shutdown mode has reached the preset waiting time ΔT. This determination is repeated until the pre-shutdown duration exceeds the preset shutdown duration, at which point the ESS is shut down. Alternatively, the system determines whether the ESS meets a trigger condition for premature shutdown. If so, the ESS is prematurely shut down.

[0145] The above is the shutdown method of the off-grid multi-unit parallel energy storage system when applied to the energy storage subsystem. Figure 10As shown in the schematic diagram of the shutdown control logic flow for the energy storage subsystem (ESS), during normal operation, the ESS determines whether it has received a shutdown command from the energy management system (EMS). Upon receiving the shutdown command, it immediately enters pre-shutdown mode. In pre-shutdown mode, it determines whether the ESS meets the trigger conditions for premature shutdown. Preferably, it determines whether the AC current of the energy storage converter (PCS) exceeds the rated value. If so, the ESS is prematurely shut down. If not, it then determines whether the pre-shutdown duration of the ESS in pre-shutdown mode has reached a preset waiting time ΔT. If so, the ESS is shut down. If not, it continues to determine whether the AC current of the ESS in the PCS exceeds the rated value and whether the pre-shutdown duration of the ESS in pre-shutdown mode has reached the preset waiting time ΔT, until the ESS is shut down.

[0146] Optionally, refer to Figure 4 A flow chart of a third embodiment, which is applied to an energy management system, wherein the off-grid multi-unit parallel energy storage system includes a plurality of parallel energy storage subsystems, and the energy management system is electrically connected to each of the energy storage subsystems;

[0147] The shutdown method of the off-grid multi-unit parallel energy storage system includes:

[0148] Step S50: determining a preset waiting time according to the number of the energy storage subsystems and the instruction issuing cycle of the energy management system;

[0149] Step S60: Every time the instruction is issued, the preset waiting time and the shutdown instruction are issued to each of the energy storage subsystems; so that the energy storage subsystem is set to the pre-shutdown mode after receiving the shutdown instruction, and the energy storage subsystem is shut down when the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time.

[0150] In this embodiment, the energy management system (ESS) sets a preset waiting time ΔT based on system latency before issuing a shutdown command. When a multi-unit parallel energy storage subsystem (ESS) operates off-grid, the energy management system (EMS) issues a shutdown command to each ESS. Due to factors such as the shutdown command issuance cycle and communication delays, there is a time difference between the energy storage converters (PCSs) within each ESS receiving the shutdown command from the EMS. This means that each ESS receives the shutdown command at different times. Assuming the shutdown command issuance cycle of the energy management system (ESS) is 100ms, and the off-grid multi-unit parallel energy storage system includes 10 ESSs, when all 10 ESSs are operating normally, shutting down all 10 ESSs requires a preset waiting time of 1 second. In other words, theoretically, the time difference between the last ESS to receive the shutdown command and the last ESS to receive the shutdown command is the preset waiting time of 1 second. Within the preset 1-second waiting time, the energy management system (ESS) issues shutdown commands to each energy storage subsystem (ESS) every 100-ms command issuance cycle, causing each ESS to switch from operating mode to pre-shutdown mode. Simultaneously, the preset 1-second waiting time is also issued to each ESS, forcing each ESS to wait in pre-shutdown mode for the preset waiting time before shutting down, rather than shutting down directly. The pre-shutdown time ΔT remains the same for each ESS.

[0151] Optionally, refer to Figure 5 The flowchart of the fourth embodiment, after the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, further includes:

[0152] Step S701: Obtain the power output of the energy storage subsystem and the load power demand;

[0153] Step S801: Determine whether the power output of the remaining energy storage subsystems meets the load power demand after one or more energy storage subsystems are shut down;

[0154] If so, an early shutdown instruction is issued to the one or more energy storage subsystems, so that the one or more energy storage subsystems meet the triggering conditions for early shutdown.

[0155] In this embodiment, after the energy management system (EMS) issues a preset wait time and shutdown command to each ESS, each ESS will subsequently complete shutdown. During the shutdown process, the power output of each ESS and the external load power requirements are obtained. If the power output of the remaining ESSs after one or more ESSs are shut down meets the load power requirements, an early shutdown command is issued to the one or more ESSs, thereby satisfying the triggering conditions for early shutdown of the ESSs. The power output and external load power requirements of each energy storage subsystem ESS can be obtained by obtaining the power output and external load power requirements of all remaining energy storage subsystems ESS after a portion of the energy storage subsystems ESS have completed shutdown. Alternatively, the power output and external load power requirements of all energy storage subsystems ESS can be obtained before the first shutdown command is issued and before all energy storage subsystems ESS have begun to shut down. In this case, an early shutdown command can be directly issued to the energy storage subsystem ESS that meets the triggering conditions for early shutdown, without issuing a shutdown command, causing it to shut down early. The early shutdown command has a higher priority than the shutdown command.

[0156] Optionally, refer to Figure 6 The flowchart of the fifth embodiment, after the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, further includes:

[0157] Step S702: receiving the first duration of waiting to receive the shutdown instruction and the second duration of internally transmitting the shutdown instruction uploaded by each energy storage subsystem;

[0158] Step S802: adjusting the preset waiting time according to the first time and the second time to generate a new preset waiting time.

[0159] In this embodiment, if Figure 9As shown in the system communication delay diagram, due to factors such as the shutdown command issuance cycle and communication delay variations, there is a time difference between the PCS within each subsystem receiving the shutdown command from the EMS. This time difference is defined as the first duration Δt1, which is the duration from when the EMS issues the shutdown command to when the ESS receives it. Furthermore, due to differences in communication time between the digital signal processor (DSP) and the reduced instruction set (RISC) chip (ARM) within the PCS, this time difference is defined as the second duration Δt2, which is the duration of transmission from the RISC chip (ARM) to the digital signal processor (DSP) within the ESS. After the EMS issues the preset waiting time and shutdown command to each ESS, it receives the first duration Δt1 and second duration Δt2 uploaded by each ESS. Based on the first duration Δt1 and second duration Δt2 of each ESS, the preset waiting time, determined based on the number of ESSs and the command issuance cycle of the EMS, is adjusted. In other words, the preset waiting time, determined based on the number of energy storage subsystems (ESS) and the instruction issuance cycle of the energy management system (EMS), can be considered the default maximum time. This time, it can be adjusted based on the first time duration Δt1 and the second time duration Δt2 to reduce the preset waiting time. Therefore, when the energy management system (EMS) first issues a shutdown instruction, the preset waiting time issued is the calculated default maximum time. When issuing subsequent shutdown instructions, it can choose to issue either the default maximum time or the preset waiting time adjusted based on the first time duration Δt1 and the second time duration Δt2.

[0160] Optionally, refer to Figure 7 The flowchart of the sixth embodiment, wherein the step of adjusting the preset waiting time according to the first time and the second time comprises:

[0161] Step S8002: determining a maximum time difference according to the largest first time length and the largest second time length, and adjusting the preset waiting time length to be greater than the maximum time difference, so as to generate a new preset waiting time length.

[0162] In this embodiment, after receiving the first duration Δt1 of receiving the shutdown command and the second duration Δt2 of internally transmitting the shutdown command uploaded by each energy storage subsystem, the maximum time difference Δt is determined using the maximum first duration MAX(Δt1) and the maximum first duration MAX(Δt2), and the preset waiting time ΔT is set to be no less than the maximum time difference Δt, that is, it is set to ΔT≥Δt, that is, the preset waiting time ΔT is set to [MAX(Δt1)+MAX(Δt2), ΔT defaults to the maximum duration]. That is, assuming that the instruction issuance cycle of the shutdown command of the energy management system ESS is 100ms, the off-grid multi-unit parallel energy storage system includes 10 energy storage subsystems ESS. When the 10 energy storage subsystems ESS are operating normally, a total preset waiting time of 1s is required to perform shutdown processing on all 10 energy storage subsystems ESS, and the default maximum duration ΔT is 1s. The maximum first duration MAX(Δt1) for each energy storage subsystem ESS to receive a shutdown command is 40ms, and the maximum second duration MAX(Δt1) for internally transmitting a shutdown command is 10ms, so the maximum time difference Δt is 50ms. Therefore, the preset waiting time ΔT can be adjusted to between [50ms, 1s].

[0163] Optionally, the shutdown method of the off-grid multi-unit parallel energy storage system further includes:

[0164] Setting the energy storage subsystem to a pre-shutdown mode according to the time sequence of issuing the shutdown instructions;

[0165] After the maximum time difference has elapsed since the shutdown instruction was issued, all the energy storage subsystems are set to a pre-shutdown mode;

[0166] After the shutdown instruction is issued, all the energy storage subsystems are shut down after the maximum time difference and the preset waiting time period during which the energy storage subsystem is in the pre-shutdown mode have passed.

[0167] In this embodiment, if Figure 11As shown in the system shutdown timeline diagram, when the energy management system (EMS) issues a shutdown command, assuming the digital signal processor (DSP) of the energy storage converter PCS in ESS1 receives the shutdown command first, it will enter pre-shutdown mode first. The digital signal processor (DSP) of the energy storage converter PCS in ESSn receives the shutdown command last and will enter pre-shutdown mode last. After the maximum time difference Δt between ESS1 and the first energy storage subsystem to receive the shutdown command, all ESS subsystems will receive the shutdown command and switch to pre-shutdown mode. ESS1, the first energy storage subsystem to receive the shutdown command, will reach the preset waiting time ΔT and shut down first. ESSn, the last energy storage subsystem to receive the shutdown command, will reach the preset waiting time ΔT and shut down last. In other words, after each ESS subsystem reaches its preset waiting time ΔT, it shuts down one by one in the order in which it received the shutdown command. After the maximum time difference between receiving the stop command and the preset waiting time in pre-shutdown mode, the energy management system (EMS) shuts down all ESS subsystems.

[0168] Optionally, after the step of setting the energy storage subsystem to the pre-shutdown mode according to the time sequence of issuing the shutdown instructions, the method further includes:

[0169] After the first energy storage subsystem that receives the shutdown instruction has waited twice as long as the preset waiting time, all energy storage subsystems are shut down.

[0170] In this embodiment, if Figure 11 As shown in the system shutdown timeline diagram, the energy storage subsystem ESSn that receives the shutdown command last reaches the preset waiting time ΔT and is shut down last. Assuming that the maximum time difference Δt for receiving the shutdown command is ΔT, starting from the reception time of the energy storage subsystem ESS1 that receives the shutdown command first, reaches the preset waiting time ΔT first, and shuts down first, the energy storage subsystem ESSn that shuts down last will complete the shutdown within 2ΔT. Therefore, in theory, within the time of 2ΔT after the energy storage converter PCS of the first energy storage subsystem ESS enters the pre-shutdown mode, the energy management system EMS will shut down all energy storage subsystems ESS.

[0171] In addition, an embodiment of the present invention further provides an off-grid multi-unit parallel energy storage system, the off-grid multi-unit parallel energy storage system comprising an energy management system and a plurality of parallel energy storage subsystems, the energy management system being electrically connected to each of the energy storage subsystems;

[0172] The energy management system determines a preset waiting time according to the number of the energy storage subsystems and the instruction issuing cycle of the energy management system;

[0173] The energy management system issues the preset waiting time and shutdown instruction to each of the energy storage subsystems at intervals of the instruction issuance cycle;

[0174] After receiving the shutdown instruction issued by the energy management system, the energy storage subsystem sets the energy storage subsystem to a pre-shutdown mode;

[0175] The energy storage subsystem determines whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time; if the pre-shutdown time reaches the preset waiting time, the energy storage subsystem is shut down.

[0176] In addition, an embodiment of the present invention also provides a shutdown device for an off-grid multi-unit parallel energy storage system. The shutdown device for the off-grid multi-unit parallel energy storage system includes: a memory, a processor, and a shutdown program for the off-grid multi-unit parallel energy storage system stored in the memory and executable on the processor. When the shutdown program for the off-grid multi-unit parallel energy storage system is executed by the processor, the steps of the shutdown method for the off-grid multi-unit parallel energy storage system as described above are implemented.

[0177] In addition, an embodiment of the present invention further provides a computer-readable storage medium, on which a shutdown program for an off-grid multi-unit parallel energy storage system is stored. When the shutdown program for the off-grid multi-unit parallel energy storage system is executed by a processor, the steps of the shutdown method for the off-grid multi-unit parallel energy storage system as described above are implemented.

[0178] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0179] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0180] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0181] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A shutdown method for an off-grid multi-unit parallel energy storage system, characterized in that: It is applied to the energy storage subsystem. The off-grid multi-unit parallel energy storage system includes multiple parallel energy storage subsystems. The shutdown method of the off-grid multi-unit parallel energy storage system comprises the following steps: After receiving the shutdown command from the energy management system, the energy storage subsystem is set to pre-shutdown mode; Determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time; If the pre-shutdown time reaches the preset waiting time, shutting down the energy storage subsystem; Before the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time, the method further includes: Determining whether the energy storage subsystem meets the triggering conditions for early shutdown; If the conditions are met, the step of shutting down the energy storage subsystem is executed; If not, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time is performed.

2. The shutdown method of the off-grid multi-unit parallel energy storage system according to claim 1, characterized in that: The step of determining whether the energy storage subsystem meets the triggering condition for early shutdown includes: Determining whether the AC current of the energy storage converter of the energy storage subsystem exceeds the rated value; If the AC current exceeds the rated value, it is determined that the energy storage subsystem meets the triggering condition for early shutdown; If the AC current does not exceed the rated value, it is determined that the energy storage subsystem does not meet the triggering condition for early shutdown.

3. The shutdown method of the off-grid multi-unit parallel energy storage system according to claim 1, characterized in that: After the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time, the method further includes: If the pre-shutdown time does not reach the preset waiting time, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time is performed.

4. A shutdown method for an off-grid multi-unit parallel energy storage system, characterized in that: It is applied to an energy management system, wherein the off-grid multi-unit parallel energy storage system includes a plurality of parallel energy storage subsystems, and the energy management system is electrically connected to each of the energy storage subsystems; the shutdown method of the off-grid multi-unit parallel energy storage system includes: Determining a preset waiting time according to the number of the energy storage subsystems and the instruction issuing cycle of the energy management system; At intervals of the instruction issuance cycle, the preset waiting time and the shutdown instruction are issued to each of the energy storage subsystems; so that the energy storage subsystem is set to a pre-shutdown mode after receiving the shutdown instruction, and the energy storage subsystem is shut down when the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time; wherein, before the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time, the energy storage subsystem further includes: Determining whether the energy storage subsystem meets the triggering conditions for early shutdown; If the conditions are met, shutting down the energy storage subsystem is executed; If not, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time is performed.

5. The shutdown method of the off-grid multi-unit parallel energy storage system according to claim 4, characterized in that: After the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, the method further includes: Obtaining the power output of the energy storage subsystem and the load power demand; Determine whether the power output of the remaining energy storage subsystems can meet the load power requirements after one or more energy storage subsystems are shut down; If so, an early shutdown instruction is issued to the one or more energy storage subsystems, so that the one or more energy storage subsystems meet the triggering conditions for early shutdown.

6. The shutdown method of the off-grid multi-unit parallel energy storage system according to claim 4, characterized in that: After the step of issuing the preset waiting time and the shutdown instruction to each of the energy storage subsystems, the method further includes: receiving a first duration of waiting to receive the shutdown command and a second duration of internally transmitting the shutdown command, uploaded by each energy storage subsystem; The preset waiting time is adjusted according to the first time and the second time to generate a new preset waiting time.

7. The shutdown method of the off-grid multi-unit parallel energy storage system according to claim 6, characterized in that: The step of adjusting the preset waiting time according to the first time and the second time comprises: A maximum time difference is determined according to the largest first time length and the largest second time length, and the preset waiting time length is adjusted to be greater than the maximum time difference, so as to generate a new preset waiting time length.

8. The shutdown method of the off-grid multi-unit parallel energy storage system according to claim 7, characterized in that: The shutdown method of the off-grid multi-unit parallel energy storage system further includes: Setting the energy storage subsystem to a pre-shutdown mode according to the time sequence of issuing the shutdown instructions; After the maximum time difference has elapsed since the shutdown instruction was issued, all the energy storage subsystems are set to a pre-shutdown mode; After the shutdown instruction is issued, all the energy storage subsystems are shut down after the maximum time difference and the preset waiting time period during which the energy storage subsystem is in the pre-shutdown mode have passed.

9. The shutdown method of the off-grid multi-unit parallel energy storage system according to claim 8, characterized in that: After the step of setting the energy storage subsystem to the pre-shutdown mode according to the time sequence of issuing the shutdown instructions, the method further includes: After the first energy storage subsystem that receives the shutdown instruction has waited twice as long as the preset waiting time, all energy storage subsystems are shut down.

10. An off-grid multi-unit parallel energy storage system, comprising an energy management system and a plurality of parallel energy storage subsystems, wherein the energy management system is electrically connected to each of the energy storage subsystems; The energy management system determines a preset waiting time according to the number of the energy storage subsystems and the instruction issuing cycle of the energy management system; The energy management system issues the preset waiting time and shutdown instruction to each of the energy storage subsystems at intervals of the instruction issuance cycle; After receiving the shutdown instruction issued by the energy management system, the energy storage subsystem sets the energy storage subsystem to a pre-shutdown mode; The energy storage subsystem determines whether a pre-shutdown time in the pre-shutdown mode reaches a preset waiting time; if the pre-shutdown time reaches the preset waiting time, shutting down the energy storage subsystem. Before determining whether the pre-shutdown time in the pre-shutdown mode reaches the preset waiting time, the energy storage subsystem further includes: Determining whether the energy storage subsystem meets the triggering conditions for early shutdown; If the conditions are met, the step of shutting down the energy storage subsystem is executed; If not, the step of determining whether the pre-shutdown time in the pre-shutdown mode reaches a preset waiting time is performed.

11. A shutdown device for an off-grid multi-unit parallel energy storage system, characterized in that: The shutdown device of the off-grid multi-unit parallel energy storage system includes: a memory, a processor, and a shutdown program of the off-grid multi-unit parallel energy storage system stored in the memory and executable on the processor. The shutdown program of the off-grid multi-unit parallel energy storage system is configured to implement the steps of the shutdown method of the off-grid multi-unit parallel energy storage system as described in any one of claims 1 to 9.

12. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a shutdown program for an off-grid multi-unit parallel energy storage system. When the shutdown program for the off-grid multi-unit parallel energy storage system is executed by the processor, the steps of the shutdown method for the off-grid multi-unit parallel energy storage system according to any one of claims 1 to 9 are implemented.

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