An automatic starting method and device based on an off-grid energy storage system

Abstract

This application relates to an automatic startup method for an off-grid energy storage system. The method includes: detecting that the DC output voltage of the photovoltaic array reaches a first preset threshold, charging the supercapacitor bank; when the voltage rises to a second preset threshold, connecting the charged supercapacitor bank to power the system's main controller and battery management system, and sending a startup command to the photovoltaic MPPT DC-DC module to charge its DC-side bus capacitor. The DC bus voltage reaches the startup threshold of the energy storage converter (PCS). After the PCS completes its internal self-test and meets the startup conditions, it performs independent inversion to establish a stable AC output voltage. At this time, the main system power supply is established. The automatic switching circuit detects that the main system power supply is valid and seamlessly switches the power supply from the startup power supply to the main system power supply. This process allows the off-grid energy storage system to autonomously recover from power failure using only photovoltaic energy when there is no external power supply or manual operation, improving system reliability, economy, and environmental adaptability.

Description

Technical Field

[0001] This application relates to the field of off-grid renewable energy power supply technology, and in particular to an automatic start-up method and device based on an off-grid energy storage system. Background Technology

[0002] With the development of new energy technologies, off-grid photovoltaic energy storage systems, with their advantages of being clean and environmentally friendly, flexible in installation, and independent of the power grid, are increasingly widely used in scenarios such as power supply in remote areas, oil well operations, border outposts, and field communication base stations, becoming core equipment for ensuring continuous power supply in these scenarios. However, the operational stability of this system is easily affected by extreme environments. Continuous rainy weather and extreme cold can cause photovoltaic modules to fail to generate electricity, deplete the energy storage medium, and consequently cause all control units to lose power, leaving the system in a "brain dead" state where it cannot restart autonomously.

[0003] Current black-start technologies all have shortcomings and cannot meet the requirements of full automation, maintenance-free operation, and high security in extreme environments. They can be specifically divided into three categories: The first type of solution relies on external power and manual intervention, such as patent CN114567004A, which requires manual connection to an external power source to trigger startup. This not only fails to achieve unattended operation and violates the original intention of autonomous operation of off-grid systems, but is also difficult to implement in remote and harsh environments.

[0004] The second type of solution involves adding a small-capacity backup power source (such as lead-acid batteries or supercapacitors) to keep the control unit in standby mode to trigger startup. However, it has fundamental drawbacks: the backup power source is subject to self-discharge and will eventually run out in extreme environments without light; its performance will be significantly degraded at extremely low temperatures, making it unable to provide stable power; and it requires regular replacement and maintenance, increasing the overall lifecycle maintenance cost and failing to meet the needs of extreme scenarios.

[0005] The third type of solution attempts to utilize internal energy storage for startup, such as patents CN104882906A and CN109217348A. However, it implicitly assumes that the "black start control unit is already powered or easily powered on." When both the main energy storage and backup power supply are exhausted, the problem of the control unit's initial power-on cannot be solved, forming a logical closed-loop loop vulnerability, and it completely fails in the extreme scenario of system "brain death."

[0006] Furthermore, existing solutions generally neglect the low-temperature characteristics of energy storage media (such as sodium batteries and lithium batteries)—their performance drops sharply and safety decreases at low temperatures, and existing strategies lack temperature-coordinated design; blind charging at low temperatures can not only easily lead to start-up failures, but may also cause irreversible damage to the battery, or even cause safety accidents, thus limiting the application of the system in high-latitude, high-altitude low-temperature scenarios.

[0007] Therefore, there is an urgent need to develop an automatic start-up method and device based on off-grid energy storage systems to solve one or more of the aforementioned problems. Summary of the Invention

[0008] In view of this, in order to solve the above-mentioned technical problems or some of the technical problems, the present invention provides an automatic start-up method and device based on an off-grid energy storage system.

[0009] Firstly, this application provides an automatic start-up method based on an off-grid energy storage system, including: The photovoltaic array outputs DC power. When the DC voltage value reaches a first set threshold, the wide-voltage input DC / DC module is activated to charge the supercapacitor bank in the startup energy buffer module. When the DC voltage value rises to the second set threshold, the first relay coil, which is directly driven by the DC bus voltage, is energized, and the normally open contact controlled by it is physically energized, connecting the charged supercapacitor bank to the startup power path, and supplying power to the system main controller and battery management system through the startup power path; After the system's main controller starts, it sends a start command to the photovoltaic MPPTDCDC module, sets the target voltage to the preset minimum operating voltage required by the energy storage converter, and charges the DC-side bus capacitor of the energy storage converter in a controllable current mode through the photovoltaic MPPTDCDC module. Once the DC bus voltage is boosted to above the minimum operating voltage of the energy storage converter, the energy storage converter is started for independent inversion to establish the AC main system power supply. The AC main system power supply is then converted to DC 24V via an uninterruptible power supply module to provide a stable DC power supply for the control system. After the dual-power automatic switching circuit detects that the main system 24V power supply is valid, it will seamlessly switch the power source from the startup power supply to the main system power supply. After the main controller of the system confirms that the main system power supply is stable, it controls the normally closed contact of the second relay to open, cutting off the startup power path. At the same time, another set of normally closed contacts of the second relay opens synchronously to disconnect the wide-voltage input DC / DC module from the photovoltaic DC bus, realizing zero-power sleep mode of the startup module. The lowest temperature of the energy storage battery cluster is obtained through the battery management system, and a corresponding temperature collaborative recovery strategy is selected and executed based on a preset temperature threshold. The temperature collaborative recovery strategy includes prohibiting charging and starting heating, current-limited charging and parallel heating, or resuming normal charging.

[0010] In one possible implementation, the first set threshold is the minimum operating voltage of the wide-voltage input DC / DC module, and the second set threshold is the physical coil pull-in voltage of the first relay, wherein the second set threshold is higher than the first set threshold; The difference between the first set threshold and the second set threshold satisfies the following: Under typical illumination conditions, when the photovoltaic DC voltage reaches the second set threshold and the first relay is triggered, the pre-charge voltage of the supercapacitor bank is higher than the effective input threshold of the dual-power automatic switching circuit for the starting power supply.

[0011] In one possible implementation, the minimum temperature is determined based on the minimum value collected by temperature sensors located at different cell positions within the energy storage battery cluster; The preset temperature threshold includes a preset safe temperature threshold and a preset operating temperature threshold, wherein the preset safe temperature threshold is lower than the preset operating temperature threshold; The step of selecting and executing a corresponding temperature collaborative recovery strategy based on a preset temperature threshold includes: The minimum temperature is compared with the preset safe temperature threshold and the preset operating temperature threshold respectively to obtain the comparison results; Based on the comparison results, a corresponding temperature collaborative recovery strategy is determined. The temperature collaborative recovery strategy is executed to implement the corresponding startup process.

[0012] In one possible implementation, determining the corresponding temperature collaborative recovery strategy based on the comparison result includes: If the minimum temperature is lower than the preset safe temperature threshold, then the temperature collaborative recovery strategy is determined to be to prohibit charging and activate the heating strategy; If the minimum temperature is lower than the preset operating temperature threshold but higher than the preset safe temperature threshold, then the temperature collaborative recovery strategy is determined to be a current-limiting charging and parallel heating strategy. If the minimum temperature is higher than the preset operating temperature threshold, then the temperature collaborative recovery strategy is determined to be a normal charging strategy.

[0013] In one possible implementation, when it is determined that the temperature collaborative recovery strategy is to disable charging and activate the heating strategy, executing the temperature collaborative recovery strategy includes: The system's main controller sends a charging prohibition command to the battery management system, which then physically shuts off the charging circuit. The system's main controller activates the heater contactor, connecting the battery heating device to the AC output of the energy storage converter. The energy storage converter operates in independent inverter mode, with photovoltaic energy prioritizing the system's self-consumption power and heater requirements. The system's main controller sends a current-limiting command to the photovoltaic MPP-DCDC module to ensure that the output power does not exceed the power limit including the heater and the system's self-consumption power demand. Temperature sensors distributed at different cell locations within the battery cluster collect the lowest temperature of the battery cluster and feed it back to the system's main controller. The lowest temperature fed back to the system's main controller is compared with the preset safe temperature threshold to obtain the comparison result; When the minimum temperature is greater than the preset safe temperature threshold, the temperature is determined to be within the acceptable range. The step of comparing the minimum temperature fed back to the system main controller with the preset safe temperature threshold is then repeated to obtain the comparison result. Based on the latest comparison result, a subsequent temperature collaborative recovery strategy is determined.

[0014] In one possible implementation, when the temperature collaborative recovery strategy is determined to be a current-limiting charging parallel heating strategy, executing the temperature collaborative recovery strategy includes: The system's main controller controls the pre-charge contactor of the energy storage battery cluster to close, so that the energy storage battery cluster is connected to the charging circuit with a limited current through the pre-charge resistor. After a fixed delay, the main contactor closes to complete the smooth connection. The system's main controller obtains the total load power on the AC side, which includes the heater power. The system main controller queries the temperature safety current mapping table based on the current lowest temperature of the battery cluster, and calibrates the upper limit of the safe charging current corresponding to the current temperature. The upper limit of the safe charging current does not exceed the battery's low temperature tolerance current. The system's main controller calculates the available current margin for charging and sets the charging current to not exceed the smaller of the safe charging current upper limit and the available margin. Initiating current-limited charging involves sending a total output current command to the photovoltaic MPPTDCDC module via the system's main controller. Photovoltaic energy prioritizes meeting the load demand, including that of the heater, while the remaining energy charges the battery within safe current limits.

[0015] The battery management system continuously collects data on the lowest temperature of the battery cluster, battery voltage, and charging current. The system's main controller monitors the load power to ensure that the charging current does not exceed the safe limit and prioritizes power supply to the load. The lowest temperature fed back to the system's main controller is compared with the preset operating temperature threshold to obtain the comparison result; When the minimum temperature exceeds the preset operating temperature threshold, the temperature is determined to be within the acceptable range. The system main controller sends a stop command to the heating device to turn off the heating function and sends a parameter adjustment command to the photovoltaic MPPTDCDC module to adjust the upper limit of the charging current to the rated charging current of the battery and switch to the normal charging recovery strategy.

[0016] Secondly, embodiments of this application provide an automatic start-up device based on an off-grid energy storage system, comprising: The detection module is used to output DC power from the photovoltaic array. When the DC voltage value reaches a first set threshold, the wide-voltage input DC / DC module is activated to charge the supercapacitor bank in the startup energy buffer module. The first startup module is used to activate the first relay coil, which is directly driven by the DC bus voltage, when the DC voltage rises to the second set threshold. The normally open contact controlled by the relay coil physically closes, connecting the charged supercapacitor bank to the startup power path, and supplying power to the system main controller and battery management system through the startup power path. The second startup module is used to send a startup command to the photovoltaic MPPTDCDC module after the system main controller is started, set the target voltage to the preset minimum operating voltage required by the energy storage converter, and charge the DC-side bus capacitor of the energy storage converter in a controllable current mode through the photovoltaic MPPTDCDC module; The first control module is used to start the energy storage converter for independent inversion and establish the AC main system power supply when the DC bus voltage is boosted to above the minimum operating voltage of the energy storage converter; the AC main system power supply is converted to DC 24V by the uninterruptible power supply module to provide a stable DC power supply for the control system. The switching module is used to seamlessly switch the power supply from the startup power supply to the main system power supply after the dual-power automatic switching circuit detects that the main system 24V power supply is valid; The second control module is used to control the normally closed contacts of the second relay to open after the main controller of the system confirms the stable power supply of the main system, thereby cutting off the starting power path. At the same time, another set of normally closed contacts of the second relay opens synchronously to disconnect the wide-voltage input DC / DC module from the photovoltaic DC bus, so as to realize the zero-power sleep mode of the starting module. The recovery module is used to obtain the lowest temperature of the energy storage battery cluster through the battery management system, and select and execute the corresponding temperature collaborative recovery strategy based on the preset temperature threshold. The temperature collaborative recovery strategy includes prohibiting charging and starting heating, current-limited charging and parallel heating, or resuming normal charging.

[0017] Thirdly, this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the automatic startup method based on an off-grid energy storage system as described in any embodiment of the first aspect.

[0018] Fourthly, this application also provides a computer storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the automatic startup method based on an off-grid energy storage system as described in any embodiment of the first aspect.

[0019] The technical solutions provided in this application have the following advantages compared with the prior art: It enables efficient, safe, and autonomous recovery of off-grid photovoltaic energy storage systems from a "brain dead" state. Relying solely on ambient photovoltaic energy, it requires no external power supply or manual operation, operating fully automatically and unmanned throughout the process, making it suitable for various unattended off-grid scenarios. It employs a physical triggering method where photovoltaic voltage directly drives mechanical relays, coupled with supercapacitor energy buffering, effectively resisting the impact of complete power failure of the control system and photovoltaic power fluctuations, resulting in extremely high startup reliability. Furthermore, with the support of MPPT DC-DC converters, the system can continue to complete subsequent energy management and voltage boost recovery. It exhibits strong tolerance and recovery capabilities for deep discharge states of energy storage batteries, enabling it to start from the extreme low charge state of the battery cluster and complete the entire system recovery process, significantly expanding the range of self-healing operating conditions and reducing maintenance requirements.

[0020] Furthermore, it creatively uses the lowest temperature of the energy storage battery as the core decision-making basis for black start and designs a graded recovery strategy. This strategy can avoid harmful charging and prioritize or parallel heating for low-temperature sodium-ion batteries, fundamentally improving the inherent safety of the start-up process. At the same time, it provides key underlying technical support for the reliable application of temperature-sensitive new energy storage media such as sodium-ion batteries in harsh environments, expanding the application boundaries of new energy storage technologies. After the black start task is completed, the start-up circuit is physically cut off by a second relay, allowing the start-up device to enter a zero-power sleep state, optimizing system energy efficiency and reducing standby losses. Only a small amount of additional hardware costs are required to completely eliminate the high cost of manual emergency recovery in remote areas, significantly improving system availability and the economic value throughout the entire life cycle. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0024] Figure 1 A flowchart illustrating an automatic startup method for an off-grid energy storage system provided in this application embodiment; Figure 2 A flowchart illustrating an automatic startup method for an off-grid energy storage system provided in this application embodiment; Figure 3 This application provides a schematic flowchart illustrating the execution of a temperature collaborative recovery strategy. Figure 4 This is a schematic diagram illustrating the execution of another temperature collaborative recovery strategy provided in an embodiment of this application. Figure 5 A schematic diagram illustrating the execution of another temperature collaborative recovery strategy provided in this application embodiment; Figure 6 A schematic diagram of an automatic start-up device based on an off-grid energy storage system provided in this application embodiment; Figure 7 A schematic diagram of another automatic start-up device based on an off-grid energy storage system provided in this application embodiment. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0027] To address the problems of slow response, high cost, and insufficient safety in the current technology of off-grid energy storage systems that rely on manual on-site intervention for startup after extreme environments or long-term outages, especially in remote areas or harsh operating conditions where traditional startup methods cannot meet the requirements for rapid and reliable system recovery, this application provides an automatic startup method and device for off-grid energy storage systems. Addressing this technical pain point, it aims to achieve autonomous recovery of off-grid energy storage systems from a complete power outage to normal operation solely based on photovoltaic energy, without external power supply or manual operation, thereby significantly improving the system's reliability, economy, and environmental adaptability.

[0028] Figure 1 A flowchart illustrating an automatic startup method for an off-grid energy storage system provided in this application embodiment is shown below. Figure 1 As shown, the method specifically includes: S101. The photovoltaic array outputs DC power. When the DC voltage value reaches a first set threshold, the wide-voltage input DC / DC module is activated to charge the supercapacitor bank in the startup energy buffer module. S102. When the DC voltage value rises to the second set threshold, the first relay coil, which is directly driven by the DC bus voltage, is energized, and the normally open contact controlled by it is physically energized, connecting the charged supercapacitor bank to the startup power path, and supplying power to the system main controller and battery management system through the startup power path; S103. After the system main controller starts, a start command is sent to the photovoltaic MPPTDCDC module to set the target voltage to the preset minimum operating voltage required by the energy storage converter, and the DC-side bus capacitor of the energy storage converter is charged by the photovoltaic MPPTDCDC module in a controllable current mode. S104. After the DC bus voltage is boosted to above the minimum operating voltage of the energy storage converter, the energy storage converter is started for independent inversion to establish the AC main system power supply; the AC main system power supply is converted to DC 24V by the uninterruptible power supply module to provide a stable DC power supply for the control system. S105. After the dual-power automatic switching circuit detects that the main system 24V power supply is valid, it will switch the power source from the startup power supply to the main system power supply without interruption. S106. After the main controller of the system confirms the stable power supply of the main system, it controls the normally closed contact of the second relay to open, cutting off the starting power path. At the same time, another set of normally closed contacts of the second relay opens synchronously to disconnect the wide-voltage input DC / DC module from the photovoltaic DC bus, realizing zero-power sleep mode of the starting module. S107. Obtain the lowest temperature of the energy storage battery cluster through the battery management system, and select and execute the corresponding temperature collaborative recovery strategy based on the preset temperature threshold. The temperature collaborative recovery strategy includes prohibiting charging and starting heating, current-limited charging and parallel heating, or resuming normal charging. In this embodiment, the DC voltage value output by the photovoltaic array is first monitored in real time. This is the initial trigger condition for system startup and provides a basic judgment basis for the subsequent startup process.

[0029] When the DC voltage value is detected to reach the first set threshold, it indicates that the photovoltaic energy has the initial start-up capability. At this time, the wide-voltage input DC / DC module is immediately started, and the module then begins to charge the capacitor bank in the energy buffer module. The charging process of the capacitor bank stores energy for the power supply of key components of the subsequent system.

[0030] As the photovoltaic array continues to generate electricity, when the DC voltage value rises further to the second set threshold, the normally open contact of the first relay controlled by the system closes, connecting the supercapacitor bank that has completed charging to the startup power path. Through this path, the system's main controller and battery management system are powered, ensuring that the core control unit can start up and begin working.

[0031] After the system main controller starts, it immediately sends a start command to the photovoltaic MPPTDCDC module and precisely sets the target voltage to the preset minimum operating voltage required by the energy storage converter. Then, the photovoltaic MPPTDCDC module charges the DC bus capacitor of the energy storage converter in a controllable current mode, creating the necessary conditions for the normal start-up of the energy storage converter.

[0032] Once the dual-power automatic switching circuit detects that the main system power supply is valid, it will seamlessly switch the power source from the startup power supply to the main system power supply, ensuring the stability and continuity of the system power supply. After the system main controller confirms that the main system power supply has achieved stable power supply, it controls the normally closed contact of the second relay to open, completely cutting off the startup power supply path. At the same time, the other set of normally closed contacts of the second relay opens synchronously, cutting off the connection between the wide-voltage input DC / DC module and the photovoltaic DC bus, causing the startup module to enter a zero-power sleep state, effectively reducing the system's standby power consumption.

[0033] Then, the lowest temperature of the energy storage battery cluster is obtained through the battery management system and compared with the preset temperature threshold. Based on the comparison result, the corresponding temperature collaborative recovery strategy is selected and executed. This strategy includes prohibiting charging and starting heating, current-limited charging and parallel heating, or resuming normal charging.

[0034] The automatic startup method for off-grid energy storage systems provided in this application embodiment achieves autonomous recovery of the off-grid energy storage system from a completely power-depleted "brain-dead" state to a normal operating state through a fully automatic startup process driven by photovoltaic energy. The entire process requires no external power supply or manual intervention, which greatly improves the reliability and ease of operation and maintenance of the system in unattended off-grid scenarios.

[0035] A physical starting method that directly triggers a mechanical relay using photovoltaic voltage, combined with energy buffer modules such as supercapacitors, effectively resists the impact of photovoltaic power fluctuations and complete power failure of the control system, ensuring high reliability during the startup process. Simultaneously, for energy storage battery clusters, especially temperature-sensitive sodium-ion batteries, a novel, tiered temperature-coordinated recovery strategy is designed, using the lowest temperature as the core decision criterion. This strategy includes prohibiting charging and initiating heating, current-limited charging with parallel heating, and resuming normal charging. This fundamentally ensures the safety of battery charging in low-temperature environments, avoids damage to batteries caused by harmful charging behaviors, and provides key technical support for the reliable application of new energy storage media in harsh environments.

[0036] Furthermore, after the black start task is completed, the start-up circuit is physically disconnected via a second relay, causing the start-up module to enter a zero-power sleep state, significantly optimizing system energy efficiency and reducing standby power consumption. With only a small increase in hardware costs, the high costs incurred in remote areas due to manual emergency recovery can be completely eliminated, significantly improving the availability, security, and life-cycle economic value of off-grid energy storage systems.

[0037] Figure 2 This is a flowchart illustrating an automatic startup method for an off-grid energy storage system provided in an embodiment of this application. Figure 2 As shown, after the system completely loses power: Phase 1: Energy Accumulation and Physical Triggering After sunrise, the photovoltaic array begins to generate electricity, and its output voltage (V_pv) gradually increases as the sunlight intensifies. When the photovoltaic DC bus voltage V_pv exceeds the first set threshold V1 (e.g., 150V), the wide-voltage input DC / DC module automatically starts, charging the supercapacitor bank C_buf in the startup energy buffer module with a small current.

[0038] As sunlight intensifies, the photovoltaic DC bus voltage V_pv continues to rise. When V_pv reaches a second set threshold V2 (e.g., 400V) that is higher than the first set threshold, the first relay coil K1 connected in parallel to the DC bus receives sufficient driving power to physically engage, causing its normally open contact K1-1 to close.

[0039] Due to the difference design between V1 and V2, when K1 is engaged, the voltage of the supercapacitor bank C_buf is already higher than the effective input threshold (e.g., 18V) of the dual-power automatic switching circuit for the starting power supply.

[0040] During this stage, the photovoltaic MPPT DC-DC module is in standby mode.

[0041] Phase Two: Control System Wake-up and System Recovery Startup After contact K1-1 closes, the starting power (from C_buf) is sent to the dual-power automatic switching circuit 7 via K2-1. Because the voltage is higher than its input effective threshold (e.g., 18V), the circuit is turned on, and the system main controller and the battery management system main control unit are powered on and started.

[0042] After the CCU starts, the following recovery process will be executed: Intelligent start-up of photovoltaic MPPT DC-CDC module: The CCU starts the photovoltaic MPPT DC-CDC module and sets the target voltage to the minimum DC bus operating voltage required by the energy storage converter (PCS) (e.g., 400V). After the module starts up, it quickly charges the DC bus capacitor of the PCS to establish a stable DC bus voltage.

[0043] Startup of the power storage converter (PCS): When the CCU detects that the DC bus voltage has reached the minimum operating voltage of the PCS, it immediately starts the PCS for independent inverter operation. The AC power output by the PCS supplies power to the uninterruptible power supply (UPS).

[0044] Main system power establishment and switching: After the uninterruptible power supply (UPS) receives AC input, it outputs a stable "main system 24V DC power supply". The dual-power automatic switching circuit detects that the main system power input is valid and the voltage is higher than the startup power supply, and automatically switches the system bus power supply to the main system power supply.

[0045] At this stage, the system's energy primarily comes from the DC power supplied by the photovoltaic array through the MPPT DC-DC module. Through the aforementioned intelligent voltage setting, the system, while establishing the main power supply, has limited the DC bus voltage to the minimum safe value required for PCS startup, thus creating optimal conditions for the safe connection of the battery cluster in the third stage.

[0046] Phase 3: Start-up circuit deactivation and safe battery connection With the system already running stably on the main system power supply, the CCU performs the following operations to complete the black-start device's exit and safely connect the energy storage battery cluster to the system: Zero-power black-start device exit: The CCU controls the second relay coil K2 to close, and its normally closed contact K2-1 is reliably opened, thereby completely cutting off the starting power path from the supercapacitor group C_buf(4). This move physically isolates the entire photovoltaic triggering and energy buffer module from the main circuit of the system, achieving zero-power hibernation of the black-start core device and eliminating any malfunctions or standby losses during normal system operation.

[0047] Battery safety access based on collaborative differential pressure management: The CCU sends a "battery access" command to the Battery Management System (BMS). Upon receiving the command, the BMS executes safety timing control logic. The key innovation of this invention lies in the fact that the DC bus voltage is now limited to a safe startup voltage by the second-stage intelligent strategy, far below the maximum capacity voltage of the MPPT DC-DC module (e.g., 950V). Therefore, the maximum potential difference encountered when the battery cluster is accessed is actively minimized. The BMS control is as follows: First, close the precharge contactor KM_pre, and the battery cluster is connected with a limited current through the precharge resistor R_pre.

[0048] After a fixed delay, the main contactor KM_main is closed, completing the smooth connection.

[0049] The embodiments of this application fundamentally change the risk mode of high voltage impact accompanying battery connection in traditional solutions, and realize the intrinsically safe recovery of the battery physical layer.

[0050] Phase 4: Temperature-based load allocation and dynamic power recovery After the energy storage battery clusters have been physically connected and the main system power supply (PCS inverter output) has been stably established, the system enters the final recovery phase.

[0051] The temperature condition assessment and heating decision-making process includes the following steps: The system main controller (CCU) 8 continuously obtains the lowest battery cluster temperature T_min from the battery management system (BMS) 9.

[0052] Low temperature detection and heating start-up: If T_min is lower than the preset safety threshold (e.g., 0°C), the system main controller (CCU)8 determines that the battery is in a low temperature danger state and needs to be raised first, and then starts heating the battery cluster.

[0053] Temperature meets target: If T_min has reached or exceeded the preset operating temperature threshold. If the heating step is skipped, the charging process can proceed directly to the next step.

[0054] Dynamic power coordination control is calculated and executed by the system main controller (CCU) 8: (1) Real-time load power monitoring and conversion The system main controller (CCU) 8 reads the total load power P_load_ac output from the PCS in real time via the AC total load meter. This power is then converted to the DC bus side to obtain the DC current I_load_dc necessary to maintain the operation of all current loads. I_load_dc = P_load_ac / (η · V_dc) Where η is the PCS inverter efficiency, V_dc is the current DC bus voltage, and I_load_dc is a precise real-time measurement feedback value.

[0055] (2) Dynamically allocate available charging current The system main controller (CCU) 8 obtains the current maximum output current I_pv_max from the photovoltaic MPPT DCDC module (22). The current margin I_chg_avail available for battery charging is: I_chg_avail = max(0, I_pv_max - I_load_dc) (3) Temperature-safe current constraint The CCU contains a sodium-ion battery temperature-safe charging current mapping table. The CCU looks up the table based on the current T_min and performs linear interpolation to obtain the upper limit of the safe charging current I_safe(T) at the current temperature.

[0056] Charging current setting: I_bat_set = min( I_safe(T), I_chg_avail ) (4) Closed-loop command issuance and execution The CCU issues a total current output command to the photovoltaic MPPT DC-CDC module: I_cmd = I_load_dc + I_bat_set The adaptive recovery process includes the following states When the temperature T_min is low: the value of I_safe(T) is very small, the system charging current is strictly limited, and most of the photovoltaic energy is used for heating to quickly raise the temperature.

[0057] As the temperature T_min gradually increases, I_safe(T) increases steadily, the allowable charging current increases, and the system gradually increases the charging power while ensuring heating.

[0058] When photovoltaic illumination fluctuates: I_pv_max changes dynamically, I_chg_avail is adjusted in real time accordingly, and the charging current changes adaptively to ensure that the system always operates stably at the total power balance point.

[0059] Absolute priority of load power supply: Under any operating condition, the supply priority of the already engaged load current I_load_dc is higher than that of charging.

[0060] Recovery and exiting mode include the following steps: Heating Exit: When T_min continues to be higher than the preset operating temperature threshold, the CCU determines that heating is complete, controls the disconnection of the heater contactor, and the heating load is removed.

[0061] Full charge: After the heater is removed, I_load_dc decreases significantly and I_chg_avail increases. The system can call up all photovoltaic power generation for fast charging until the battery reaches the predetermined state, and the system fully recovers to the schedulable operation mode.

[0062] Furthermore, to improve the reliability of the black-start device during long-term normal system operation and to achieve complete zero-power sleep mode, the embodiments of this application also provide the following optimized embodiments: The second relay (K2) is equipped with a second normally closed contact (not shown in the figure, but can be labeled K2-2). This second normally closed contact (K2-2) is connected in series between the photovoltaic DC bus (V_pv) and the common connection point of the input terminals of the photovoltaic self-powered physical trigger module and the starting energy buffer module. In other words, the input power of the first relay coil (K1) and the wide-voltage input DC / DC module is taken from the photovoltaic DC bus through this second normally closed contact (K2-2).

[0063] Its working logic and beneficial effects are as follows: When the system is completely de-energized, the second relay (K2) is in the released state, and all its normally closed contacts (including the original K2-1 and the newly added K2-2) are closed, allowing photovoltaic energy to be successfully connected to the black start device and triggering the subsequent black start process. Once the main system power supply is stably established, the system main controller (CCU) controls the second relay (K2) to engage, and all its normally closed contacts open. This measure achieves dual isolation at the physical level. The original contact (K2 - 1) is disconnected, cutting off the power supply path for startup.

[0064] The newly added contact (K2 - 2) is disconnected, completely cutting off the entire photovoltaic self-powered physical trigger module and the start-up energy buffer module from the photovoltaic DC bus.

[0065] The above method fundamentally eliminates the possibility of the first relay (K1) malfunctioning due to the increase in photovoltaic voltage during normal system operation (such as at sunrise), while completely de-energizing the wide-voltage DC / DC module, thereby ensuring that the black start device achieves true zero-power sleep mode in non-working state and has the longest operating life.

[0066] It should be noted that, in this embodiment, the second relay (K2) must be a relay whose contacts meet the requirements of the photovoltaic DC bus voltage and current levels.

[0067] In one possible implementation, the first set threshold is the minimum operating voltage of the wide-voltage input DC / DC module, and the second set threshold is the physical coil pull-in voltage of the first relay, wherein the second set threshold is higher than the first set threshold; The difference between the first set threshold and the second set threshold satisfies the following: Under typical illumination conditions, when the photovoltaic DC voltage reaches the second set threshold and the first relay is triggered, the pre-charge voltage of the supercapacitor bank is higher than the effective input threshold of the dual-power automatic switching circuit for the starting power supply.

[0068] In this embodiment, the first set threshold is the minimum operating voltage of the wide-voltage input DC / DC module, ensuring the basic conditions for module startup; while the second set threshold is set as the physical coil pull-in voltage of the first relay, and this value is higher than the first set threshold, so that the relay will only be triggered after the photovoltaic voltage drives the DC / DC module to start up and charge the capacitor bank, thus reserving sufficient charging time for the capacitor bank.

[0069] The difference between the first set threshold and the second set threshold needs to ensure that, under typical lighting conditions, when the photovoltaic DC voltage rises to the second set threshold and triggers the first relay, the supercapacitor bank in the energy buffer module has been fully pre-charged, and its pre-charge voltage can be stably higher than the effective input threshold of the dual-power automatic switching circuit for the starting power supply.

[0070] By properly configuring the differential, the unstable startup power supply voltage or inability to meet the switching circuit requirements due to insufficient capacitor charging is effectively avoided, ensuring that the system's main controller and battery management system can obtain continuous and reliable power supply, laying a solid foundation for the smooth execution of subsequent control processes.

[0071] In one possible implementation, the minimum temperature is determined based on the minimum value collected by temperature sensors located at different cell positions within the energy storage battery cluster; The preset temperature threshold includes a preset safe temperature threshold and a preset operating temperature threshold, wherein the preset safe temperature threshold is lower than the preset operating temperature threshold; The step of selecting and executing a corresponding temperature collaborative recovery strategy based on a preset temperature threshold includes: The preset minimum temperature is compared with the preset safe temperature threshold and the preset operating temperature threshold, respectively, to obtain the comparison results; Based on the comparison results, a corresponding temperature collaborative recovery strategy is determined. The temperature collaborative recovery strategy is executed to implement the corresponding startup process.

[0072] In this embodiment, the minimum temperature is determined by real-time data collection from multiple temperature sensors deployed at different cell locations within the energy storage battery cluster. The minimum value is then selected as the criterion for judgment. This method comprehensively captures extreme temperature conditions within the battery cluster and avoids judgment bias caused by neglecting local high or low temperatures.

[0073] The preset temperature threshold is specifically divided into a preset safe temperature threshold and a preset working temperature threshold. The preset safe temperature threshold is set lower than the preset working temperature threshold, forming a dual standard for temperature judgment. When selecting and executing the corresponding temperature collaborative recovery strategy based on the preset temperature threshold, the obtained preset minimum temperature is first compared with the preset safe temperature threshold and the preset working temperature threshold respectively, thereby obtaining the specific comparison results.

[0074] Based on different comparison results, corresponding temperature recovery strategies are determined. For example, when the preset minimum temperature is lower than the preset safe temperature threshold, it indicates that the battery is currently in an extremely cold state. Charging at this time may cause irreversible damage to the battery. Therefore, a strategy of prohibiting charging and starting heating is implemented to raise the battery temperature to a safe range through the heating device. When the preset minimum temperature is between the preset safe temperature threshold and the preset operating temperature threshold, it indicates that although the battery temperature has left the danger zone, it has not yet reached the ideal operating state. At this time, a strategy of current-limited charging and parallel heating is adopted. While controlling the charging current to prevent the battery from overheating, heating continues to promote the battery temperature to rise further to the operating temperature. When the preset minimum temperature is higher than the preset operating temperature threshold, it indicates that the battery temperature conditions are good. At this time, a strategy of resuming normal charging is implemented to ensure that the system stores energy with optimal efficiency.

[0075] By implementing the above-mentioned temperature-coordinated recovery strategy, precise start-up process control can be achieved under different temperature conditions, ensuring that the energy storage battery can resume operation efficiently under safe conditions.

[0076] In one possible implementation, determining the corresponding temperature collaborative recovery strategy based on the comparison result includes: If the preset minimum temperature is lower than the preset safe temperature threshold, then the temperature collaborative recovery strategy is determined to be to prohibit charging and activate the heating strategy; If the preset minimum temperature is lower than the preset operating temperature threshold but higher than the preset safe temperature threshold, then the temperature collaborative recovery strategy is determined to be a current-limiting charging and parallel heating strategy. If the preset minimum temperature is higher than the preset operating temperature threshold, then the temperature collaborative recovery strategy is determined to be a normal charging recovery strategy.

[0077] In this embodiment, the specific execution logic of the strategy to prohibit charging and activate heating when the minimum temperature is lower than the preset safe temperature threshold is as follows: The system main controller (CCU) sends a "prohibit charging" command to the battery management system (BMS) and simultaneously controls the heater contactor to engage, activating the battery heating device and connecting it as a new load to the AC output terminal of the PCS. During this period, a dynamic power collaborative recovery strategy is executed. First, real-time load power monitoring and calculation are performed. At this time, the load power is added to the heater. According to the sodium-ion battery temperature-safe charging current mapping table internally stored in the CCU, I_bat_set=0. The CCU issues a total current output command to the photovoltaic MPPT DC-DC module: I_cmd = I_load_dc. The current output by the photovoltaic MPPT DC-DC module (I_pv_max) will prioritize meeting the current load current (I_load_dc) demand to maximize the battery temperature. At this time, the charging current setpoint (I_bat_set) is forcibly set to zero to ensure that the battery does not perform charging operations at extremely low temperatures, avoiding battery performance degradation or safety risks caused by low-temperature charging.

[0078] During the startup phase, the system consumes only a small amount of power. Through simple photovoltaic power monitoring and heater setting adjustment, it can safely and effectively complete the low-temperature heating of the battery without the need for the battery to provide power.

[0079] If the preset minimum temperature falls between the preset safe temperature threshold and the preset operating temperature threshold, a current-limited charging and parallel heating strategy is executed. The CCU retrieves the corresponding I_safe(T) from the temperature-safe charging current mapping table based on the current T_min, and simultaneously calculates I_chg_avail. The charging current setpoint I_bat_set is the smaller value between I_safe(T) and I_chg_avail. At this time, the heater remains operational. After meeting the load requirements, a portion of the photovoltaic energy is used to charge the battery with a small current at a safe rate, while the other portion continues to be used for heating, achieving parallel charging and heating. This ensures battery safety while gradually increasing battery capacity and temperature.

[0080] When the preset minimum temperature exceeds the preset operating temperature threshold, the normal charging strategy is activated. At this time, the heater contactor disconnects, and the heating load is deactivated. The system main controller (CCU) dynamically calculates I_chg_avail based on the real-time I_pv_max and I_load_dc, and combines this with I_safe(T) at the current temperature (which is usually already at the maximum allowable charging current of the battery), setting I_bat_set = min(I_safe(T), I_chg_avail). This allows the system to charge the battery with the maximum safe current when photovoltaic conditions permit, quickly restoring the battery's state of charge until it reaches the predetermined fully charged or dispatchable state.

[0081] Figure 3 This is a schematic diagram illustrating the execution of a temperature collaborative recovery strategy according to an embodiment of this application, such as... Figure 3 As shown, when it is determined that the temperature collaborative recovery strategy is to disable charging and activate the heating strategy, the execution of the temperature collaborative recovery strategy includes: S301, The system main controller sends a charging prohibition command to the battery management system, and the battery management system executes a physical shutdown of the charging circuit; S302. The system main controller controls the heater contactor to engage, connecting the battery heating device to the AC output terminal of the energy storage converter; S303, the energy storage converter operates in independent inverter mode, and photovoltaic energy is prioritized to meet the system's self-consumption power and heater requirements; S304. The system main controller sends a current limiting command to the photovoltaic MPPTDCDC module to ensure that the output power does not exceed the power limit value including the heater and the system's self-consumption power demand. S305: By using temperature sensors distributed at different cell locations within the battery cluster, the lowest temperature of the battery cluster is collected and fed back to the system's main controller; S306. Compare the lowest temperature fed back to the system main controller with the preset safe temperature threshold to obtain the comparison result; S307. When the minimum temperature is greater than the preset safe temperature threshold, the temperature is determined to meet the standard. The step of comparing the minimum temperature fed back to the system main controller with the preset safe temperature threshold is executed again to obtain the comparison result. The subsequent temperature collaborative recovery strategy is determined based on the latest comparison result.

[0082] In this embodiment, when executing the strategy of prohibiting charging and initiating heating, the system main controller (CCU) first sends a clear "charging prohibition command" to the photovoltaic MPPT DC-DC module. The core function of this command is to lock the module's charging current output channel, ensuring from the control logic level that the charging current I_bat_set flowing to the battery is forced to zero, preventing any possible charging behavior from damaging the low-temperature battery. At the same time, the CCU sends a "heating start command" to the temperature collaborative management module. After this command is triggered, the heating devices pre-placed in key parts of the energy storage battery cluster (such as between cells, near the tabs, etc.) will immediately start operating. The heating devices will operate according to preset power parameters (e.g., the initial heating power calculated based on the total capacity of the battery cluster and the target heating rate) to maximize heat conduction efficiency, so that the generated heat can be quickly and evenly transferred to each cell, avoiding local overheating or uneven heating.

[0083] During the heating process, multiple high-precision temperature sensors distributed across different cells in the battery cluster continuously collect real-time temperature data from each monitoring point and feed this data back to the system's main controller (CCU). The CCU processes the feedback data and selects the minimum value as the preset minimum temperature T_min for the current battery cluster. Subsequently, the system periodically compares this T_min with a preset safe temperature threshold (e.g., every 10 seconds). To ensure accuracy and avoid misjudgments caused by instantaneous temperature fluctuations, the CCU only determines that the battery temperature has reached the target when three consecutive comparisons (or other numbers set according to system requirements) show that T_min is greater than the preset operating temperature threshold. Once the temperature reaches the target, the CCU immediately sends a "stop command" to the heating device to stop operating and prevent overheating. Afterwards, the system will re-execute the step of "comparing the lowest temperature fed back to the system main controller with the preset safe temperature threshold and obtaining the comparison result". At this time, since T_min is higher than the preset safe temperature threshold, the system will determine the temperature collaborative recovery strategy to be executed next based on the latest comparison result (i.e., the comparison between T_min and the preset operating temperature threshold), such as switching to the current-limited charging parallel heating strategy or restoring the normal charging strategy.

[0084] Figure 4 A schematic diagram illustrating the execution of another temperature collaborative recovery strategy provided in this application embodiment, as shown below. Figure 4 As shown, when the temperature collaborative recovery strategy is determined to be a current-limiting charging and parallel heating strategy, the execution of the temperature collaborative recovery strategy includes: S401, The system main controller controls the pre-charge contactor of the energy storage battery cluster to close, so that the energy storage battery cluster is connected to the charging circuit with a limited current through the pre-charge resistor. After a fixed delay, the main contactor closes to complete the smooth connection. S402. The system main controller obtains the total load power on the AC side, which includes the heater power. S403. The system main controller queries the temperature safety current mapping table based on the current lowest temperature of the battery cluster, and calibrates the upper limit of the safe charging current corresponding to the current temperature. The upper limit of the safe charging current does not exceed the battery's low-temperature tolerance current. S404. The system main controller calculates the available current margin for charging and sets the charging current to not exceed the smaller of the safe charging current upper limit and the available margin. S405. Start current-limited charging. Send the total output current command to the photovoltaic MPPTDCDC module through the system main controller. The photovoltaic energy will first meet the load demand, including the heater, and the remaining energy will charge the battery within the safe current limit.

[0085] S406. Utilize the battery management system to continuously collect data on the minimum temperature of the battery cluster, battery voltage, and charging current; S407. The system's main controller monitors the load power to ensure that the charging current does not exceed the safe limit and prioritizes power supply to the load. S408. Compare the lowest temperature fed back to the system main controller with the preset operating temperature threshold to obtain the comparison result; S409. When the minimum temperature is greater than the preset operating temperature threshold, the temperature is determined to be up to standard. The system main controller sends a stop command to the heating device to turn off the heating function and sends a parameter adjustment command to the photovoltaic MPPTDCDC module to adjust the upper limit of the charging current to the rated charging current of the battery and switch to the normal charging recovery strategy.

[0086] In this embodiment, when executing the current-limited charging and parallel heating strategy, the system first queries a preset temperature-safe charging current mapping table based on the current lowest temperature T_min of the battery cluster. This mapping table is generated based on low-temperature charging characteristic data provided by the battery manufacturer and extensive experimental verification. It can accurately calibrate the upper limit of the safe charging current I_safe(T) at different temperatures, and this upper limit is strictly controlled within the battery's low-temperature tolerance current range to ensure that the battery will not be damaged by overcurrent during charging. Next, the system main controller (CCU) controls the pre-charge contactor of the energy storage battery cluster to close. At this time, the energy storage battery cluster is connected to the charging circuit through the pre-charge resistor. The function of the pre-charge resistor is to limit the inrush current at the moment of initial charging to avoid damage to the battery and circuit components. After a fixed delay (e.g., 300ms, which is calculated based on the resistance and capacitance of the pre-charge resistor to ensure that the capacitor is fully charged), the main contactor closes, and the battery cluster is smoothly connected to the main charging circuit, completing the safe establishment of the charging circuit.

[0087] Subsequently, the system initiates the current-limited charging process. The CCU sends a "current-limited charging command" to the photovoltaic MPPT DC-DC module, explicitly instructing the module to output current according to the previously calibrated safe charging current limit I_safe(T). Simultaneously, the CCU sends a "heating start command" to the temperature collaborative management module, activating the heating device attached to the battery cluster. The heating device continues to operate at the preset power. At this time, after the electricity generated by the photovoltaic system prioritizes meeting the real-time load power demand, the remaining available current (I_chg_avail = I_pv_max - I_load_dc) will be used, within the constraint of the safe charging current limit I_safe(T), partly for small-current charging of the batteries and partly to continue powering the heating device, thus achieving parallel operation of charging and heating.

[0088] During this process, the Battery Management System (BMS) continuously collects key parameters such as the minimum temperature of the battery cluster, the voltage of each individual cell, and the actual charging current, and uploads this data to the system main controller (CCU) in real time. The CCU then monitors changes in load power in real time, dynamically adjusts the distribution of charging current to ensure that the charging current never exceeds the safe upper limit I_safe(T), and prioritizes ensuring stable power supply to the load to avoid power interruption due to charging or heating. The system periodically compares the returned minimum temperature T_min with the preset operating temperature threshold. When three consecutive comparisons show that T_min is greater than the preset operating temperature threshold, the CCU determines that the battery temperature has reached the ideal operating state. At this time, the CCU sends a "stop command" to the heating device to turn off the heating function to reduce unnecessary energy consumption. Simultaneously, the CCU sends a "parameter adjustment command" to the photovoltaic MPPTDCDC module to adjust the upper limit of the charging current from I_safe(T) to the rated charging current of the battery, thereby switching to a normal charging strategy and enabling the system to charge at a higher efficiency.

[0089] Figure 5 This is a schematic diagram illustrating the execution of another temperature collaborative recovery strategy provided in an embodiment of this application, as shown below. Figure 5 As shown, when it is determined that the temperature collaborative recovery strategy is a normal charging recovery strategy, executing the temperature collaborative recovery strategy includes: S501. The system main controller sends a normal charging command to the photovoltaic MPPTDCDC module to configure the charging mode as a constant current and constant voltage composite mode, and sets the initial value of the charging current to the rated charging current of the battery; S502. Monitor the AC-side load power through the system main controller and convert the load power into DC-side load current; S503: Collects the individual cell voltage, total voltage, minimum temperature, and remaining capacity of the energy storage battery cluster through the battery management system and feeds it back to the system main controller in real time; S504. Monitor the output current and voltage stability of the photovoltaic MPP-DCDC module through the system's main controller; S505: When the system detects that the voltage of a single battery cell exceeds the upper limit, the battery temperature exceeds the safety threshold, or the charging current fluctuates abnormally, the main controller of the system sends a current limiting or stop command to the photovoltaic MPPTDCDC module, and triggers an alarm signal at the same time. S506 When the battery management system detects that the remaining power of the battery cluster has reached the preset full charge threshold, or the total battery voltage has reached the constant voltage stage setting value and the charging current has dropped to the preset termination current, it determines that charging is complete. The system main controller sends a charging stop command or a float charging mode switching command to the photovoltaic MPPTDCDC module to stop active charging or switch to low current float charging state, thus completing the entire normal charging recovery process.

[0090] In this embodiment, when executing the normal charging recovery strategy, the system main controller (CCU) first sends a "normal charging command" to the photovoltaic MPP-DCDC module. This command configures the module's charging mode to the industry-standard constant current / constant voltage (CC / CV) composite mode. This mode can efficiently charge the battery, first charging it to a certain voltage with a constant current, and then completing the subsequent charging process with a constant voltage. Simultaneously, the initial value of the charging current is set to the battery's rated charging current to ensure that the battery capacity is restored at the optimal rate when the battery temperature is suitable and the photovoltaic power is sufficient. In this mode, the CCU needs to monitor the AC-side load power in real time. Since the internal energy conversion of the system involves AC and DC conversion, the CCU converts the monitored AC-side load power into the DC-side load current (I_load_dc) based on parameters such as the current inverter efficiency, in order to accurately calculate the remaining available charging current after the photovoltaic power meets the load. At the same time, the battery management system (BMS) continuously collects various key parameters of the energy storage battery cluster, including the voltage of each individual cell, the total voltage of the battery cluster, the minimum temperature of the battery cluster, and the current remaining capacity (SOC), and feeds this data back to the CCU in real time and accurately. These parameters are important bases for the CCU to perform charging control and safety protection.

[0091] The CCU also monitors the output current and voltage of the photovoltaic MPPT DCDC module in real time to ensure that it is working normally and to avoid affecting the battery charging process due to abnormal module output.

[0092] Throughout the normal charging process, the system employs multiple safety protection mechanisms. When the CCU detects, via BMS feedback data, that the voltage of any single battery cell exceeds the preset upper limit, the battery temperature exceeds the safety threshold, or that the charging current exhibits abnormal fluctuations (such as sudden increases, sudden decreases, or continuous over-limits) via the MPPT DCDC module, the CCU will immediately send a current-limiting command to the photovoltaic MPPT DCDC module or directly send a stop command to rapidly reduce the charging current or interrupt the charging process to protect the battery from damage. Simultaneously, the system will trigger corresponding alarm signals to notify maintenance personnel to handle the abnormal situation promptly.

[0093] When the Battery Management System (BMS) detects that the remaining charge (SOC) of the battery cluster has reached a preset full-charge threshold (e.g., 95% or 100%, the specific threshold can be set according to system requirements), or although the remaining charge has not reached the full-charge threshold, but the total battery voltage has reached the set value of the constant voltage stage, and the charging current has dropped to the preset termination current (usually 5%-10% of the rated charging current), the BMS determines that the battery charging is complete. At this time, the BMS feeds this status information back to the CCU, and the CCU then sends a charging stop command to the photovoltaic MPPT DC-DC module to stop the module from actively charging; or, according to the system settings, sends a float charging mode switching command to switch the module to a low-current float charging state to maintain the battery's full charge state and prevent overcharging. Thus, the entire normal charging recovery process is successfully completed, and the energy storage system has been restored to a fully charged or dispatchable state, capable of responding to load demands or participating in grid dispatch at any time.

[0094] Figure 6 A schematic diagram of an automatic start-up device based on an off-grid energy storage system provided in this application embodiment is shown below. Figure 6 As shown, the device specifically includes: The detection module 601 is used to output DC power from the photovoltaic array. When the DC voltage value reaches a first set threshold, it activates the wide-voltage input DC / DC module to charge the supercapacitor bank in the startup energy buffer module. The first startup module 602 is used to activate the first relay coil, which is directly driven by the DC bus voltage, when the DC voltage value rises to the second set threshold. The normally open contact controlled by the relay coil physically closes, connecting the charged supercapacitor bank to the startup power path, and supplying power to the system main controller and battery management system through the startup power path. The second startup module 603 is used to send a startup command to the photovoltaic MPPTDCDC module after the system main controller is started, set the target voltage to the preset minimum operating voltage required by the energy storage converter, and charge the DC side bus capacitor of the energy storage converter in a controllable current mode through the photovoltaic MPPTDCDC module; The first control module 604 is used to start the energy storage converter for independent inversion and establish the AC main system power supply when the DC bus voltage is boosted to above the minimum operating voltage of the energy storage converter; the AC main system power supply is converted to DC 24V by the uninterruptible power supply module to provide a stable DC power supply for the control system. The switching module 605 is used to seamlessly switch the power supply from the startup power supply to the main system power supply after the dual-power automatic switching circuit detects that the main system 24V power supply is valid; The second control module 606 is used to control the normally closed contact of the second relay to open after the main controller of the system confirms the stable power supply of the main system, thereby cutting off the starting power path. At the same time, another set of normally closed contacts of the second relay opens synchronously to disconnect the wide-voltage input DC / DC module from the photovoltaic DC bus, so as to realize the zero-power sleep mode of the starting module. The recovery module 607 is used to obtain the lowest temperature of the energy storage battery cluster through the battery management system, and select and execute the corresponding temperature collaborative recovery strategy based on the preset temperature threshold. The temperature collaborative recovery strategy includes prohibiting charging and starting heating, current-limiting charging and parallel heating, or resuming normal charging.

[0095] In one possible implementation, the first set threshold is the minimum operating voltage of the wide-voltage input DC / DC module, and the second set threshold is the physical pull-in voltage of the coil of the first relay. The second set threshold is higher than the first set threshold. The difference between the first set threshold and the second set threshold satisfies the following: under typical illumination conditions, when the photovoltaic DC voltage reaches the second set threshold and the first relay is triggered, the pre-charge voltage of the supercapacitor bank is higher than the effective input threshold of the dual-power automatic switching circuit for the starting power supply.

[0096] In one possible implementation, the minimum temperature is determined based on the minimum value collected by temperature sensors distributed at different cell locations within the energy storage battery cluster; the preset temperature threshold includes a preset safe temperature threshold and a preset operating temperature threshold, wherein the preset safe temperature threshold is lower than the preset operating temperature threshold; the execution module is further configured to select and execute a corresponding temperature collaborative recovery strategy based on the preset temperature threshold, including: comparing the preset minimum temperature with the preset safe temperature threshold and the preset operating temperature threshold respectively to obtain a comparison result; determining the corresponding temperature collaborative recovery strategy based on the comparison result; and executing the temperature collaborative recovery strategy to implement the corresponding startup process. In one possible implementation, the recovery module 607 is further configured to: if the minimum temperature is lower than the preset safe temperature threshold, determine that the temperature collaborative recovery strategy is to prohibit charging and start a heating strategy; if the minimum temperature is lower than the preset operating temperature threshold but higher than the preset safe temperature threshold, determine that the temperature collaborative recovery strategy is to use a current-limiting charging and parallel heating strategy; and if the minimum temperature is higher than the preset operating temperature threshold, determine that the temperature collaborative recovery strategy is to restore normal charging.

[0097] In one possible implementation, when the temperature-coordinated recovery strategy is determined to be charging prohibition and heating strategy activation, the recovery module 607 is further configured to: send a charging prohibition command to the battery management system via the system main controller; the battery management system executes a physical shutdown of the charging circuit; control the heater contactor to engage, connecting the battery heating device to the AC output terminal of the energy storage converter; the energy storage converter operates in independent inverter mode, prioritizing photovoltaic energy to meet the system's self-consumption and heater requirements; send a current-limiting command to the photovoltaic MPPTDCDC module via the system main controller to ensure that the output power does not exceed the power limit value including the heater and system self-consumption requirements; collect the lowest temperature of the battery cluster via temperature sensors distributed at different cell locations within the battery cluster and feed it back to the system main controller; compare the lowest temperature fed back to the system main controller with a preset safe temperature threshold to obtain a comparison result; when the lowest temperature is greater than the preset safe temperature threshold, the temperature is deemed to be within acceptable limits, and the step of comparing the lowest temperature fed back to the system main controller with the preset safe temperature threshold to obtain a comparison result is repeated; and determine the subsequent temperature-coordinated recovery strategy based on the latest comparison result.

[0098] In one possible implementation, when the temperature collaborative recovery strategy is determined to be a current-limited charging and parallel heating strategy, the recovery module 607 is further used by the system main controller to control the pre-charge contactor of the energy storage battery cluster to close, so that the energy storage battery cluster is connected to the charging circuit with a limited current through the pre-charge resistor, and the main contactor is closed after a fixed delay to complete the smooth connection; the system main controller obtains the total load power on the AC side, which includes the heater power; the system main controller queries the temperature safe current mapping table according to the current lowest temperature of the battery cluster, and calibrates the upper limit of the safe charging current corresponding to the current temperature, which does not exceed the battery's low-temperature tolerance current; the system main controller calculates the current margin available for charging, and sets the charging current to not exceed the smaller value between the upper limit of the safe charging current and the available margin; current-limited charging is started, and the system main controller sends a total output current command to the photovoltaic MPPTDCDC module, so that the photovoltaic energy first meets the load demand including the heater, and the remaining energy charges the battery within the safe current limit. The battery management system continuously collects the minimum temperature of the battery cluster, battery voltage, and charging current; the system main controller monitors the load power to ensure that the charging current does not exceed the safety limit and prioritizes the power supply to the load; the minimum temperature fed back to the system main controller is compared with the preset operating temperature threshold to obtain the comparison result; when the minimum temperature is greater than the preset operating temperature threshold, it is determined that the temperature meets the standard, and the system main controller sends a stop command to the heating device to turn off the heating function, and sends a parameter adjustment command to the photovoltaic MPPTDCDC module to adjust the upper limit of the charging current to the rated charging current of the battery, and switches to the normal charging recovery strategy.

[0099] In one possible implementation, when the temperature-coordinated recovery strategy is determined to be a normal charging strategy, the recovery module 607 is further configured to send a normal charging command to the photovoltaic MPPTDCDC module via the system main controller to configure the charging mode as a constant current / constant voltage composite mode and set the initial value of the charging current to the battery's rated charging current; monitor the AC-side load power through the system main controller and convert the load power into a DC-side load current; collect the individual cell voltage, total voltage, minimum temperature, and remaining capacity of the energy storage battery cluster through the battery management system and feed it back to the system main controller in real time; and monitor the photovoltaic MPPTDCDC module through the system main controller. The module's output current and voltage stability are monitored. When a single battery cell voltage exceeds the upper limit, the battery temperature exceeds the safety threshold, or the charging current fluctuates abnormally, the system's main controller sends a current limiting or stop command to the photovoltaic MPPTDCDC module, while simultaneously triggering an alarm signal. When the battery management system detects that the remaining charge of the battery cluster has reached the preset full charge threshold, or the total battery voltage has reached the constant voltage stage setting value and the charging current has dropped to the preset termination current, the charging is deemed complete. The system's main controller then sends a charging stop command or a float charging mode switching command to the photovoltaic MPPTDCDC module to stop active charging or switch to a low-current float charging state, completing the entire normal charging recovery process.

[0100] The automatic start-up device based on an off-grid energy storage system provided in this embodiment can be as follows: Figure 6 The automatic start-up device based on the off-grid energy storage system shown can perform actions such as... Figure 1-5 The automatic startup of the off-grid energy storage system is based on all steps, thereby achieving Figure 1-5 The technical effects of automatic startup based on off-grid energy storage systems are shown below. Please refer to [link / reference] for details. Figure 1-5 The relevant descriptions are presented concisely and will not be elaborated upon here.

[0101] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0102] Figure 7 A schematic diagram of another automatic start-up device based on an off-grid energy storage system provided in this application embodiment is shown below. Figure 7 As shown, the device specifically includes: Photovoltaic triggering module: The output of the photovoltaic array (1) forms a high-voltage DC bus (voltage V_pv, which varies with the light intensity). The first relay coil K1 (2) is connected in parallel to this DC bus through a current-limiting resistor R1 (21). The resistance value of the current-limiting resistor R1 (21) is matched with the DC resistance value of the first relay coil K1 (2). Its design purpose is to form a suitable load together with the coil under typical light conditions for photovoltaic startup, to ensure that the photovoltaic DC bus voltage V_pv can be stably increased and maintained above the physical pull-in threshold of the relay (the second set threshold, such as V_pv>400V), thereby providing the driving power required for reliable pull-in of the coil K1 (2). This process is completely driven directly by the photovoltaic voltage and does not depend on any powered controller.

[0103] The input of the photovoltaic MPPT DC-DC module (22) is also connected to the high-voltage DC bus, and its output is connected to the DC side of the energy storage converter (PCS). The system main controller (CCU) controls the start-up and shutdown of the module and sets its current and voltage.

[0104] Energy buffer path: Consists of a wide-voltage input DC / DC module (3) with self-starting function and a supercapacitor bank C_buf (4). The input terminal of the wide-voltage DC / DC module (3) is connected to the photovoltaic DC bus. Its key feature is that when the voltage at its input port reaches the first set threshold V1 (e.g., 150V), the startup circuit inside the module can work, the module enters normal operation, and begins to charge the supercapacitor bank C_buf (4) at the output terminal. The first set threshold V1 (the minimum operating voltage of the module) must be lower than the second set threshold V2 (the relay pull-in voltage, e.g., 400V), and the design of the difference between the two must ensure that the supercapacitor has sufficient pre-charging time.

[0105] Start-up control module: The positive terminal of the supercapacitor bank C_buf(4) is connected in series with the normally open contact K1-1(5) of the first relay and the normally closed contact K2-1(6) of the second relay, and then connected to the "start-up power input" terminal of the dual-power automatic switching circuit (7). The state of contact K1-1(5) is controlled by coil K1(2).

[0106] Power Management Module: Dual-Power Automatic Switching Circuit (7) has two inputs (start-up power supply and main system power supply) and one system bus output (24V). It has low-voltage blocking and automatic selection logic: when the voltage of a certain input is higher than its internally set effective threshold (such as 18V), the power supply is allowed to be connected; when both power supplies are effective, it automatically switches to the one with the higher voltage as the output. The "Main System 24V DC Power Supply" output by the Uninterruptible Power Supply (UPS) (20) is connected to its "Main System Power Input" terminal.

[0107] Intelligent Control and Decision Module (Partial): Includes a system main controller (CCU) (8) powered by the system bus, a battery management system (BMS) main control unit (9), a photovoltaic MPPT DC-DC module (22), and auxiliary control circuits for the energy storage converter (PCS). A relay drive circuit (10), controlled by the system main controller (CCU) (8), drives the second relay coil K2 (11). Coil K2 (11) controls the opening and closing of its normally closed contact K2-1 (6).

[0108] Here are some examples of key parameter settings: Minimum input voltage (first set threshold V1) of wide voltage DC / DC module 3: 150V First relay K1 coil pull-in voltage (second set threshold V2): 400V Supercapacitor bank C_buf capacitance: 20F, system voltage 24V Dual power supply switching circuit effective input threshold: 18V PCS minimum operating voltage: 50V Temperature threshold: Safe start temperature T_safe = 0°C.

[0109] Parameter setting guidelines: The voltage thresholds (V1 = 150V, V2 = 400V) are set based on the IV curve of a typical photovoltaic module string and relay characteristics. The difference between V1 and V2 ensures that the voltage of the supercapacitor can be higher than 18V when K1 is energized under typical illumination. The temperature threshold (T_safe = 0°C) is an example value set for the characteristics of sodium-ion batteries. In specific applications, it can be adjusted according to the low-temperature charge and discharge characteristics of the battery type (such as lithium iron phosphate batteries, ternary lithium batteries, etc.). For example, the preset safe temperature threshold for lithium iron phosphate batteries can be set to 5°C to avoid the risk of lithium dendrite growth caused by low-temperature charging. The selection of the supercapacitor bank capacity needs to comprehensively consider the instantaneous power consumption during system startup (such as the total power of components such as controllers, sensors, and relay drives) and the continuous power supply time requirements to ensure stable energy support for key control modules before the main system power is established.

[0110] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0111] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a specific order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0112] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An automatic start-up method based on an off-grid energy storage system, characterized in that... ,include: The photovoltaic array outputs DC power. When the DC voltage value reaches a first set threshold, the wide-voltage input DC / DC module is activated to charge the supercapacitor bank in the startup energy buffer module. When the DC voltage value rises to the second set threshold, the first relay coil, which is directly driven by the DC bus voltage, is energized, and the normally open contact controlled by it is physically energized, connecting the charged supercapacitor bank to the startup power path, and supplying power to the system main controller and battery management system through the startup power path; After the system's main controller starts, it sends a start command to the photovoltaic MPPTDCDC module, sets the target voltage to the preset minimum operating voltage required by the energy storage converter, and charges the DC-side bus capacitor of the energy storage converter in a controllable current mode through the photovoltaic MPPTDCDC module. Once the DC bus voltage is boosted to above the minimum operating voltage of the energy storage converter, the energy storage converter is started for independent inversion to establish the AC main system power supply. The AC main system power supply is then converted to DC 24V via an uninterruptible power supply module to provide a stable DC power supply for the control system. After the dual-power automatic switching circuit detects that the main system 24V power supply is valid, it will seamlessly switch the power source from the startup power supply to the main system power supply. After the main controller of the system confirms that the main system power supply is stable, it controls the normally closed contact of the second relay to open, cutting off the startup power path. At the same time, another set of normally closed contacts of the second relay opens synchronously to disconnect the wide-voltage input DC / DC module from the photovoltaic DC bus, realizing zero-power sleep mode of the startup module. The lowest temperature of the energy storage battery cluster is obtained through the battery management system, and a corresponding temperature collaborative recovery strategy is selected and executed based on a preset temperature threshold. The temperature collaborative recovery strategy includes prohibiting charging and starting heating, current-limited charging and parallel heating, or resuming normal charging.

2. The method according to claim 1, characterized in that... The first set threshold is the minimum operating voltage of the wide-voltage input DC / DC module, and the second set threshold is the physical coil pull-in voltage of the first relay. The second set threshold is higher than the first set threshold. The difference between the first set threshold and the second set threshold satisfies the following: Under typical illumination conditions, when the photovoltaic DC voltage reaches the second set threshold and the first relay is triggered, the pre-charge voltage of the supercapacitor bank is higher than the effective input threshold of the dual-power automatic switching circuit for the starting power supply.

3. The method according to claim 1, characterized in that... The minimum temperature is determined based on the minimum value collected by temperature sensors located at different cell positions within the energy storage battery cluster. The preset temperature threshold includes a preset safe temperature threshold and a preset operating temperature threshold, wherein the preset safe temperature threshold is lower than the preset operating temperature threshold; The step of selecting and executing a corresponding temperature collaborative recovery strategy based on a preset temperature threshold includes: The minimum temperature is compared with the preset safe temperature threshold and the preset operating temperature threshold respectively to obtain the comparison results; Based on the comparison results, a corresponding temperature collaborative recovery strategy is determined. The temperature collaborative recovery strategy is executed to implement the corresponding startup process.

4. The method according to claim 3, characterized in that... The step of determining the corresponding temperature collaborative recovery strategy based on the comparison results includes: If the minimum temperature is lower than the preset safe temperature threshold, then the temperature collaborative recovery strategy is determined to be to prohibit charging and activate the heating strategy; If the minimum temperature is lower than the preset operating temperature threshold but higher than the preset safe temperature threshold, then the temperature collaborative recovery strategy is determined to be a current-limiting charging and parallel heating strategy. If the minimum temperature is higher than the preset operating temperature threshold, then the temperature collaborative recovery strategy is determined to be a normal charging strategy.

5. The method according to claim 3, characterized in that... When it is determined that the temperature collaborative recovery strategy is to disable charging and activate the heating strategy, executing the temperature collaborative recovery strategy includes: The system's main controller sends a charging prohibition command to the battery management system, which then physically shuts off the charging circuit. The system's main controller activates the heater contactor, connecting the battery heating device to the AC output of the energy storage converter. The energy storage converter operates in independent inverter mode, with photovoltaic energy prioritizing the system's self-consumption power and heater requirements. The system's main controller sends current-limiting commands to the photovoltaic MPP-DCDC modules to ensure that the output power does not exceed the power limits for the heater and the system's self-consumption power requirements. Temperature sensors distributed at different cell locations within the battery cluster collect the lowest temperature of the battery cluster and feed it back to the system's main controller. The lowest temperature fed back to the system's main controller is compared with the preset safe temperature threshold to obtain the comparison result; When the minimum temperature is greater than the preset safe temperature threshold, the temperature is determined to be within the acceptable range. The step of comparing the minimum temperature fed back to the system main controller with the preset safe temperature threshold is then repeated to obtain the comparison result. Based on the latest comparison result, a subsequent temperature collaborative recovery strategy is determined.

6. The method according to claim 3, characterized in that... When the temperature collaborative recovery strategy is determined to be a current-limiting charging and parallel heating strategy, executing the temperature collaborative recovery strategy includes: The system's main controller controls the pre-charge contactor of the energy storage battery cluster to close, so that the energy storage battery cluster is connected to the charging circuit with a limited current through the pre-charge resistor. After a fixed delay, the main contactor closes to complete the smooth connection. The system's main controller obtains the total load power on the AC side, which includes the heater power. The system main controller queries the temperature safety current mapping table based on the current lowest temperature of the battery cluster, and calibrates the upper limit of the safe charging current corresponding to the current temperature. The upper limit of the safe charging current does not exceed the battery's low temperature tolerance current. The system's main controller calculates the available current margin for charging and sets the charging current to not exceed the smaller of the safe charging current upper limit and the available margin. Initiate current-limited charging by sending a total output current command to the photovoltaic MPPTDCDC module through the system main controller. The photovoltaic energy will prioritize meeting the load demand, including the heater, and the remaining energy will charge the battery within the safe current limit. The battery management system continuously collects data on the lowest temperature of the battery cluster, battery voltage, and charging current. The system's main controller monitors the load power to ensure that the charging current does not exceed the safe limit and prioritizes power supply to the load. The lowest temperature fed back to the system's main controller is compared with the preset operating temperature threshold to obtain the comparison result; When the minimum temperature exceeds the preset operating temperature threshold, the temperature is determined to be within the acceptable range. The system main controller sends a stop command to the heating device to turn off the heating function and sends a parameter adjustment command to the photovoltaic MPPTDCDC module to adjust the upper limit of the charging current to the rated charging current of the battery and switch to the normal charging recovery strategy.

7. The method according to claim 3, characterized in that... When it is determined that the temperature collaborative recovery strategy is a normal charging recovery strategy, executing the temperature collaborative recovery strategy includes: The system's main controller sends a normal charging command to the photovoltaic MPP-DCDC module to configure the charging mode as a constant current-constant voltage composite mode and sets the initial value of the charging current to the battery's rated charging current. The system's main controller monitors the AC-side load power and converts it into DC-side load current. The battery management system collects data on the individual cell voltages, total voltage, minimum temperature, and remaining charge of the energy storage battery clusters and feeds this data back to the system's main controller in real time. The system's main controller monitors the output current and voltage stability of the photovoltaic MPP-DCDC module. When a single cell voltage exceeds the upper limit, the battery temperature exceeds the safety threshold, or the charging current fluctuates abnormally, the system's main controller sends a current-limiting or stop command to the photovoltaic MPPTDCDC module, and simultaneously triggers an alarm signal. When the battery management system detects that the remaining charge of the battery cluster has reached the preset full charge threshold, or the total battery voltage has reached the constant voltage stage setting value and the charging current has dropped to the preset termination current, it determines that charging is complete. The system main controller sends a charging stop command or a float charging mode switching command to the photovoltaic MPPTDCDC module to stop active charging or switch to low current float charging state, thus completing the entire normal charging recovery process.

8. An automatic start-up device based on an off-grid energy storage system, characterized in that... ,include: The detection module is used to output DC power from the photovoltaic array. When the DC voltage value reaches a first set threshold, the wide-voltage input DC / DC module is activated to charge the supercapacitor bank in the startup energy buffer module. The first startup module is used to activate the first relay coil, which is directly driven by the DC bus voltage, when the DC voltage rises to the second set threshold. The normally open contact controlled by the relay coil physically closes, connecting the charged supercapacitor bank to the startup power path, and supplying power to the system main controller and battery management system through the startup power path. The second startup module is used to send a startup command to the photovoltaic MPPTDCDC module after the system main controller is started, set the target voltage to the preset minimum operating voltage required by the energy storage converter, and charge the DC-side bus capacitor of the energy storage converter in a controllable current mode through the photovoltaic MPPTDCDC module; The first control module is used to start the energy storage converter for independent inversion and establish the AC main system power supply when the DC bus voltage is boosted to above the minimum operating voltage of the energy storage converter; the AC main system power supply is converted to DC 24V by the uninterruptible power supply module to provide a stable DC power supply for the control system. The switching module is used to seamlessly switch the power supply from the startup power supply to the main system power supply after the dual-power automatic switching circuit detects that the main system 24V power supply is valid; The second control module is used to control the normally closed contacts of the second relay to open after the main controller of the system confirms the stable power supply of the main system, thereby cutting off the starting power path. At the same time, another set of normally closed contacts of the second relay opens synchronously to disconnect the wide-voltage input DC / DC module from the photovoltaic DC bus, so as to realize the zero-power sleep mode of the starting module. The recovery module is used to obtain the lowest temperature of the energy storage battery cluster through the battery management system, and select and execute the corresponding temperature collaborative recovery strategy based on the preset temperature threshold. The temperature collaborative recovery strategy includes prohibiting charging and starting heating, current-limited charging and parallel heating, or resuming normal charging.

9. A playback device, characterized in that... ,include: Memory, used to store computer programs; A processor is configured to execute a computer program stored in the memory, wherein when the computer program is executed, it implements the method described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that... When the computer program is executed by the processor, it implements the method described in any one of claims 1-7.

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