Low temperature heating system of energy storage system, control method, device and storage medium

Abstract

The application discloses a low-temperature heating system of an energy storage system, a control method, equipment and a storage medium, and the system comprises a main loop, a heating loop, a current-limiting anti-reverse branch and a BMS module; the main loop is in series connection of a battery module, a main loop relay and an inverter, the positive electrode of the battery module is connected to the direct current side of the inverter, and the negative electrode is connected to the negative electrode of the direct current side of the inverter; the direct current side of the inverter is connected to a photovoltaic system, and the alternating current side is connected to a public power grid. One end of the heating loop is connected between the direct current side of the inverter and the main loop relay, and the other end is in series connection of a heating control relay and an electrothermal film. The current-limiting anti-reverse branch is in series connection of an anti-reverse diode, an auxiliary relay and a current-limiting resistor and is in parallel connection at both ends of the main loop relay. The BMS module is used for controlling the on-off of the main loop relay, the heating control relay and the auxiliary relay, collecting the cell temperature, the battery SOC and the main loop current parameters. The application can realize the low-temperature preheating of the battery in cooperation with the photovoltaic and external energy of the power grid, and effectively reduces the heating energy consumption of the battery itself.

Description

Technical Field

[0001] This application relates to the field of thermal management technology for energy storage batteries, specifically a low-temperature heating system, control method, equipment, and storage medium for an energy storage system. Background Technology

[0002] With its superior safety performance, long cycle life, and low cost, lithium iron phosphate (LFP) batteries have become the mainstream technology in the electrochemical energy storage industry. However, this battery system has a significant weakness in low-temperature adaptability: when the ambient temperature drops below 0°C, the battery's charge acceptance capability decreases sharply. Charging the battery at this temperature causes lithium metal to continuously precipitate on the surface of the negative electrode. The resulting lithium dendrites gradually pierce the battery separator, easily causing internal short circuits within the cell, and in severe cases, even thermal runaway. Therefore, a low-temperature heating system is an essential component for the stable operation of energy storage batteries in cold regions.

[0003] Currently, the mainstream low-temperature preheating solution in the industry is electric heating film technology, but this solution has many shortcomings in practical applications, specifically in three aspects:

[0004] First, the single power source shortens battery life. Existing heating solutions rely entirely on the battery's own power for heating. In low-temperature environments, the additional discharge of the battery will further exacerbate cell polarization, accelerate battery aging and degradation, and directly shorten the overall cycle life of the energy storage battery.

[0005] Secondly, energy utilization is inefficient, and backup power supply capacity is insufficient. This technology lacks a coordinated dispatch mechanism between the power grid, external energy sources such as photovoltaics, and the energy storage battery. Under normal operating conditions where the power grid and photovoltaics can supply power normally, all energy consumption for low-temperature heating is still borne by the battery itself, resulting in the battery being in a low-charge state for extended periods. In extreme cases such as sudden grid failures or photovoltaic power generation failures, the battery cannot output sufficient backup power, significantly reducing the power supply stability and reliability of the energy storage system.

[0006] Third, the control logic is incomplete and lacks self-recovery capability under extreme operating conditions. The existing control strategy does not have an autonomous recovery mechanism designed for extreme scenarios with multiple overlapping faults. If the cell temperature drops below 0°C, the grid experiences a prolonged power outage, photovoltaic power generation stops, and the battery state of charge falls below the heating start threshold, the system will be unable to start self-heating due to insufficient power. Even if the grid and external energy sources such as photovoltaics subsequently return to normal, to avoid the safety risk of lithium plating during low-temperature charging, the system will continuously disconnect the main circuit and prohibit charging, ultimately causing the entire energy storage system to fail and unable to restart autonomously. It must rely on on-site manual reset by maintenance personnel to restore operation, significantly increasing maintenance costs and equipment downtime losses.

[0007] In summary, the industry urgently needs to develop a novel low-temperature heating circuit and control scheme for lithium iron phosphate energy storage. This circuit should be able to efficiently coordinate with external clean energy sources such as photovoltaics and the power grid to preheat the battery at low temperatures, significantly reducing the battery's own heating energy consumption. It should also possess the ability to autonomously recover from extreme failure scenarios. This would specifically address engineering challenges in high-altitude and cold regions, such as rapid battery life degradation, insufficient backup power supply, and the inability to self-reset after a failure, thus meeting the long-term stable operation requirements of cold-weather environments. Summary of the Invention

[0008] This application addresses the aforementioned shortcomings of existing technologies by proposing a low-temperature heating system, control method, equipment, and storage medium for energy storage systems. This overcomes the drawbacks of existing low-temperature heating systems for lithium iron phosphate energy storage batteries, which rely on the battery itself for power supply, fail to fully utilize external energy sources such as the power grid and photovoltaics, and lack a self-recovery mechanism under extreme fault scenarios, resulting in accelerated battery life depletion, insufficient backup power, and inability to recover automatically after system crashes.

[0009] According to one aspect of this application, a low-temperature heating system for an energy storage system is provided, comprising:

[0010] A main circuit is formed by connecting a battery module, a main circuit relay, and an inverter in series. The positive terminal of the battery module is connected to the positive DC terminal of the inverter, and the negative terminal of the battery module is connected to the negative DC terminal of the inverter. The inverter is connected to an external energy source.

[0011] A heating circuit is provided, with one end of the heating circuit connected between the positive DC terminal of the inverter and the main circuit relay, and the other end connected in series with a heating control relay and an electric heating film and then connected to the negative terminal of the battery module.

[0012] A current-limiting anti-reverse branch is formed by a reverse protection diode, an auxiliary relay, and a current-limiting resistor connected in series, and the current-limiting anti-reverse branch is connected in parallel across the two ends of the main circuit relay;

[0013] A BMS module is used to collect data in real time on the cell temperature T, battery SOC, main circuit current I, and the power supply status of the external energy source of the battery module; based on the cell temperature T, battery SOC, main circuit current I, and the power supply status of the external energy source, it controls the opening and closing of the main circuit relay, heating control relay, and auxiliary relay to control the power supply of the electrothermal film to heat the battery module.

[0014] Preferably, the auxiliary relay closes when the temperature of the battery module is below 0°C and the electrothermal film is powered by the external energy source, and opens when the main circuit relay closes; when the auxiliary relay closes, the current-limiting anti-reverse branch provides the inverter with a detectable voltage signal of the battery module through the current-limiting resistor.

[0015] Preferably, the external energy source includes a photovoltaic system and a public power grid, wherein the photovoltaic system is connected to the DC side of the inverter and the public power grid is connected to the AC side of the inverter.

[0016] According to one aspect of this application, a method for controlling cryogenic heating in an energy storage system is provided, comprising:

[0017] The BMS module collects the cell temperature T, battery SOC, main circuit current I, and power supply status of the external energy source in real time. Based on the cell temperature T, battery SOC, main circuit current I, and power supply status of the external energy source, it controls the opening and closing of the main circuit relay, heating control relay, and auxiliary relay to control the power supply of the heating film to heat the battery module.

[0018] Preferably, the following steps are also included:

[0019] The BMS module has four preset operating conditions for the battery module built in:

[0020] Operating condition 1: The cell temperature T ∈ [0℃, 10℃);

[0021] Operating Condition 2: The cell temperature T < 0℃, and the external energy source is supplying power normally;

[0022] Operating Condition 3: The cell temperature T < 0℃, the external energy source is not supplying power, and the battery SOC > 5%;

[0023] Operating Condition 4: The cell temperature T < 0℃, the external energy source does not supply power, and the battery SOC ≤ 5%;

[0024] When the BMS module determines that it is in operating condition one, it controls the heating control relay to close, the auxiliary relay to open, and the main circuit relay to maintain its current state; when the cell temperature T≥15℃, the BMS module controls the heating control relay to open.

[0025] When the BMS module determines that it is in operating condition two, it controls the heating control relay to close, the main circuit relay to open, and the auxiliary relay to close. When the cell temperature T≥5℃, it controls the main circuit relay to close, the auxiliary relay to open, and continues to heat the battery module through the heating control relay until the cell temperature T≥15℃, at which point the heating control relay is disconnected.

[0026] When the BMS module determines that it is in operating condition three, if the battery SOC is ≥ 35%, it controls the main circuit relay to close, the auxiliary relay to open, and the heating control relay to close; if the battery SOC is ∈ (5%, 35%), it controls the main circuit relay to close, the auxiliary relay to open, and the heating control relay to open.

[0027] When the BMS module determines that it is in operating condition four, it controls the main circuit relay, heating control relay and auxiliary relay to disconnect, and the energy storage system enters a hibernation standby state.

[0028] Preferably, when operating condition one is in operation and the external energy source is supplying power normally, the BMS module controls the battery module not to supply power to the heating film.

[0029] Preferably, the inverter is connected to a load on the AC side. When in operating condition two, after the BMS module controls the main circuit relay to close, if the inverter does not supply power to the heating film and receives a power supply request from the load, it controls the auxiliary relay to open, the heating control relay to open, and the main circuit relay to close to supply power to the load. After the load is powered, the heating control relay is closed again.

[0030] Preferably, under operating condition three and when the battery SOC ≥ 35%, the BMS module determines the battery temperature T based on the cell temperature T and the preset target temperature T. ref Temperature difference ΔT = T ref -T and the battery SOC, the average heating power P of the electrothermal film is calculated according to the following formula. avg :

[0031] P avg =P max ×min{1, k×ΔT+λ×(SOC−35%)},

[0032] Among them, P max The rated power of the electrothermal film;

[0033] P avg For average heating power, 0 < P avg ≤P max ;

[0034] k is the temperature difference gain coefficient, k > 0;

[0035] λ is the state of charge correction factor, λ > 0;

[0036] The BMS module is based on a duty cycle D=P avg / P max The heating control relay is subjected to low-frequency periodic on / off control. Within a single control cycle, the on-time of the heating control relay is D×T. cycle The disconnection duration is (1-D)×T cycle T cycle To preset the control cycle, so that the electrothermal film operates at an average power P avg The battery module is heated; when the cell temperature T reaches T... ref When the heating control relay is disconnected, 0 < D ≤ 1.

[0037] According to one aspect of this application, a cryogenic heating control device for an energy storage system is provided, comprising:

[0038] processor;

[0039] A memory in which executable instructions of the processor are stored;

[0040] The processor is configured to execute the steps of the cryogenic heating control method for the energy storage system by executing the executable instructions.

[0041] According to one aspect of this application, a computer-readable storage medium is provided for storing a program that, when executed, implements the steps of the cryogenic heating control method of the above-described energy storage system.

[0042] The beneficial effects of the above technical solution are:

[0043] This application addresses the aforementioned shortcomings of existing technologies by proposing a low-temperature heating system, control method, equipment, and storage medium for an energy storage system. An electrothermal film is connected in parallel between the inverter's DC side and the battery's main circuit. The BMS selects the heating power supply path based on the operating status of the external energy source. In scenarios where external energy is available, the battery does not participate in heating discharge, reducing cell polarization and aging caused by additional battery discharge under low-temperature conditions, thus extending battery cycle life. Based on a multi-condition differentiated control strategy considering cell temperature, external energy operating status, and battery state of charge, external energy is prioritized for heating when available, maintaining a high battery state of charge. When no external energy is available, heating start-up and forced stop thresholds are set to preserve battery reserve capacity, providing backup power during grid failures and improving the power supply reliability of the energy storage system.

[0044] Other features and advantages of this application, as well as the structure and operation of various embodiments thereof, will be described in detail below with reference to the accompanying drawings. It should be noted that this application is not limited to the specific embodiments described herein. The embodiments given herein are merely illustrative. Attached Figure Description

[0045] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0046] Figure 1 This is a circuit diagram of a low-temperature heating system for an energy storage system according to this application;

[0047] Figure 2 This is a schematic diagram of the structure of a cryogenic heating control device for an energy storage system according to this application;

[0048] Figure 3 This is a schematic diagram of the structure of the computer-readable storage medium of this application.

[0049] Reference numerals: 1 Battery module; 2 Main circuit relay; 21 Main circuit relay driver; 3 Inverter; 4 Heating control relay; 41 Heating control relay driver; 5 Heating film; 6 Anti-reverse diode; 7 Auxiliary relay; 71 Auxiliary relay driver; 8 Current limiting resistor; 9 BMS module; 10 Photovoltaic system; 11 Public power grid; 91 Voltage sampling transmission line; 92 Temperature sampling transmission line; 93 Current sampling transmission line.

[0050] The features and advantages of this application will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Throughout the drawings, the same reference numerals identify corresponding elements. In the drawings, the same reference numerals generally indicate the same, functionally similar, and / or structurally similar elements. Detailed Implementation

[0051] 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, and 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.

[0052] The terms "first," "second," and similar words used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Words such as "including" or "comprising" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0053] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0054] The present application will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the application.

[0055] According to one aspect of this application, a low-temperature heating system for an energy storage system is provided, which mainly includes a main circuit, a heating circuit, a current-limiting and reverse-current protection branch, and a battery management system (BMS).

[0056] Figure 1 This is a circuit diagram of the cryogenic heating system of the energy storage system of this application. Figure 1 The cryogenic heating system of the energy storage system shown in the figure, wherein,

[0057] The main circuit consists of battery module 1, main circuit relay 2, and inverter 3 connected in series. The positive terminal of battery module 1 is connected to the positive DC terminal of inverter 3, and the negative terminal of battery module 1 is connected to the negative DC terminal of inverter 3. Inverter 3 is used to connect to external energy sources to realize the conversion and transmission of electrical energy.

[0058] One end of the heating circuit is connected to the node between the positive DC terminal of the inverter 3 and the main circuit relay 2, and the other end is connected in series with a heating control relay 4 and an electric heating film 5 and then connected to the negative terminal of the battery module 1 to form an independent heating power supply path. The electric heating film is placed near the battery module.

[0059] The current-limiting reverse protection branch consists of a reverse protection diode 6, an auxiliary relay 7, and a current-limiting resistor 8 connected in series. This branch is connected in parallel across the main circuit relay 2, serving both voltage sampling and reverse current suppression functions. As those skilled in the art will understand, the current-limiting resistor 8 is used to limit the maximum current of the current-limiting reverse protection branch, preventing overcurrent damage to the reverse protection diode 6 at the moment the main circuit relay 2 is disconnected or under abnormal operating conditions.

[0060] BMS module 9 collects real-time data on the cell temperature T, battery SOC, main circuit current I, and external energy supply status of battery module 1. Based on these data, it outputs control signals to control the on / off states of main circuit relay 2, heating control relay 4, and auxiliary relay 7 via main circuit relay driver 21, heating control relay 4, and auxiliary relay 7. This regulates the power supply status of the heating film 5, achieving low-temperature heating control of battery module 1. Battery SOC refers to the state of charge of the battery, expressed as a percentage. Specifically, BMS module 9 collects the cell temperature T of battery module 1 via temperature sampling transmission line 92, the main circuit current I via current sampling transmission line 93, and the voltage of battery module 1 via voltage sampling transmission line 91. The battery SOC is calculated using a SOC estimation algorithm based on the battery voltage, main circuit current I, and cell temperature T.

[0061] Preferably, the auxiliary relay 7 closes when the temperature of the battery module 1 is below 0°C and the heating film 5 is powered by an external energy source, to prevent the battery module 1 from being charged below 0°C. It also opens when the main circuit relay 2 closes, completely cutting off the current-limiting anti-reverse branch, preventing continuous leakage current and power loss generated by the anti-reverse diode 6 during normal operation, and improving the overall system efficiency. When the auxiliary relay 7 closes, the current-limiting anti-reverse branch provides a detectable voltage signal of the battery module 1 to the inverter 3 via the current-limiting resistor 8. This allows the inverter 3 to determine the battery status by detecting the voltage signal at the battery module 1 terminal. If the battery voltage signal cannot be detected, an error will be reported and energy delivery will stop. This also ensures normal system startup when the grid power supply is restored or photovoltaic power generation resumes.

[0062] Preferably, when the cell temperature T of battery module 1 is below 0°C, auxiliary relay 7 closes to block the reverse current from flowing into battery module 1 from the public power grid 11 side or photovoltaic system 10 side to form a charging circuit. The DC side of inverter 3 can be connected to distributed DC clean power sources such as photovoltaic systems, and the AC side is connected to the public power grid 11 through the grid interface. The BMS control system of this application integrates a cell NTC temperature acquisition module, switch drive, and current sampling to realize intelligent control of the entire system.

[0063] Preferably, the external energy source includes a photovoltaic system 10 and a public power grid 11, with the photovoltaic system 10 connected to the DC side of the inverter 3 and the public power grid 11 connected to the AC side of the inverter 3.

[0064] According to one aspect of this application, a method for controlling cryogenic heating in an energy storage system is provided, comprising:

[0065] BMS module 9 collects real-time data on the cell temperature T, battery SOC, main circuit current I, and external energy supply status of battery module 1. Based on the cell temperature T, battery SOC, main circuit current I, and external energy supply status, it executes a three-level differentiated heating control and protection strategy, controlling the opening and closing of main circuit relay 2, heating control relay 4, and auxiliary relay 7 to control the power supply to the heating film 5 to heat battery module 1.

[0066] Preferably, the following steps are also included:

[0067] The four operating conditions of the BMS module 9 built into the battery module 1 are as follows:

[0068] Operating condition 1: Cell temperature T∈[0℃,10℃);

[0069] Operating Condition 2: Cell temperature T < 0℃, and external power supply is normal;

[0070] Operating Condition 3: Cell temperature T < 0℃, no external power supply, and battery SOC > 5%;

[0071] Operating Condition 4: Cell temperature T < 0℃, no external power supply, and battery SOC ≤ 5%;

[0072] When BMS module 9 determines that it is in operating condition one, it controls the heating control relay 4 to close, the auxiliary relay 7 to open, and the main circuit relay 2 to maintain its current state. When the cell temperature T ≥ 15℃, BMS module 9 controls the heating control relay 4 to open. Specifically, when the BMS detects any cell temperature T ∈ [0℃, 10℃) through NTC sensors distributed on the surface of the cells in battery module 1, it determines that the system is in operating condition one. The BMS triggers the cell low-temperature heating logic and sends a heating request signal to the inverter 3. The inverter 3 feeds back the current external energy working status message. After the BMS completes the message parsing, it closes the heating control relay 4 through the drive circuit. The main circuit relay 2 maintains its original working state, and the auxiliary relay 7 remains open. The normal charging and discharging operation of the energy storage system is not affected by the heating circuit action.

[0073] As those skilled in the art will understand, when there is external energy supply such as the power grid or photovoltaic, the power grid or photovoltaic will preferentially supply heating power to the heating film 5 via the DC side of the inverter 3, and the battery module 1 will not output heating power. Under the condition that there is no external power supply such as the power grid or photovoltaic, the system will automatically switch the power supply source and the battery module 1 will supply power to the heating film 5. The exit condition is that when the temperature of all cells T is ≥15℃, the BMS will disconnect the heating control relay 4 through the drive circuit to end the cell heating process.

[0074] When BMS module 9 determines that it is in operating condition 2, it controls the heating control relay 4 to close, the main circuit relay 2 to open, and the auxiliary relay 7 to close. When the cell temperature T≥5℃, it controls the main circuit relay 2 to close, the auxiliary relay 7 to open, and continues to heat the battery module 1 through the heating control relay 4 until the cell temperature T≥15℃, at which point the heating control relay 4 is disconnected, ending the heating process.

[0075] Specifically, the BMS detects that any cell temperature T < 0℃ using NTC sensors distributed on the surface of the cells in battery module 1, and the grid status detection module detects that the grid is supplying power normally or that external energy sources such as photovoltaics are generating power normally. In this case, the system is determined to be in operating condition two. The BMS sends a heating request to inverter 3, which then sends a status message indicating that the grid and external energy sources such as photovoltaics are operating normally. After parsing the message, the BMS immediately disconnects the main circuit relay 2, closes the auxiliary relay 7, and simultaneously closes the heating control relay 4. When the temperature of all cells T ≥ 5℃, the main circuit relay 2 is closed and the auxiliary relay 7 is simultaneously disconnected. The system resumes normal charging and discharging functions and automatically switches to operating condition one to continue heating until the temperature of all cells T ≥ 15℃.

[0076] As those skilled in the art will understand, when the main circuit relay 2 is disconnected, the charging path between the inverter 3 and the battery module 1 is completely blocked, preventing the inverter 3 from charging the battery module 1 below 0°C. At this time, the heating film 5 is powered solely by external energy sources such as the grid or photovoltaics through the inverter 3, and the battery module 1 does not participate in any energy flow. After the auxiliary relay 7 is closed, if the BMS detects that the inverter 3 has not started DC-side heating power supply, and at the same time receives a load power supply request requiring the battery to discharge, it immediately disconnects the auxiliary relay 7 and closes the main circuit relay 2, suspending the current heating process. After the load power supply task is completed, the heating logic corresponding to the second operating condition is retried.

[0077] In one optional embodiment of this example, the AC side of the inverter 3 is also connected to a load. When the battery module 1 is in operating condition two and the BMS module controls the main circuit relay 2 to close, if the inverter 3 is not currently supplying power to the heating film 5 and receives a power supply request from the load, the BMS module controls the auxiliary relay 7 to open and the heating control relay 4 to open, while keeping the main circuit relay 2 closed to prioritize power supply to the load; after the load power supply ends, the heating control relay 4 is closed again to resume the low-temperature heating process.

[0078] When BMS module 9 determines that it is in operating condition 3, the BMS module performs differentiated control according to the battery SOC interval: if the battery SOC ≥ 35%, the main circuit relay 2 is closed, the auxiliary relay 7 is opened, and the heating control relay 4 is closed; if the battery SOC ∈ (5%, 35%), the main circuit relay 2 is closed, the auxiliary relay 7 is opened, the heating control relay 4 is opened, and heating is suspended to preserve the battery's basic charge and ensure the core power supply capability.

[0079] Specifically, the BMS detects any cell temperature T < 0℃ and no effective external power supply when the cell surface of battery module 1 is detected by NTC sensors distributed on the cell surface, and the battery SOC > 5%, thus determining that the system is in operating condition three. The BMS sends a heating request to inverter 3, and inverter 3 reports back an abnormal status message regarding the current operation of the power grid and external energy sources such as photovoltaics. After parsing the message, the BMS executes the corresponding control logic based on the battery SOC. When the battery SOC ≥ 35%, the main circuit relay 2 is closed, the auxiliary relay 7 is kept open, and the heating control relay 4 is closed. The cell is heated by the power supply from battery module 1 to the heating film 5. If the SOC ≤ 5% during the heating process, the heating control relay 4 is immediately disconnected to forcibly stop heating to avoid over-discharge of battery module 1, and the system automatically switches to operating condition four. When the battery SOC ∈ (5%, 35%), the main circuit relay 2 is kept closed, the auxiliary relay 7 is kept open, and the heating control relay 4 is disconnected. The system remains in standby mode, waiting for the power grid to restore power or the photovoltaic system to resume power generation. During heating or standby, once the power grid or the photovoltaic system resumes power generation, the system immediately switches to operating mode two and executes the corresponding control logic.

[0080] When BMS module 9 determines that the system is in operating condition four, it disconnects the main circuit relay 2, heating control relay 4, and auxiliary relay 7, and the energy storage system enters a hibernation standby state to avoid the risk of over-discharge of the battery. Specifically, the BMS detects that any cell temperature T < 0℃, there is no effective external power supply, and the battery SOC ≤ 5% through NTC sensors distributed on the surface of the battery cells in battery module 1, including the case where the SOC drops to 5% during the heating process in operating condition three. In this case, the system is determined to be in operating condition four. The BMS immediately disconnects the main circuit relay 2, heating control relay 4, and auxiliary relay 7, cutting off all power circuits and maintaining power supply only to the BMS core control and communication modules, and the system enters a hibernation standby state. As those skilled in the art will understand, cutting off all power-consuming circuits and preserving the remaining battery power to the maximum extent ensures the continuous normal operation of the system's control and communication functions, continuously monitors the status of the power grid and external energy sources such as photovoltaics, and reserves basic power for subsequent system self-recovery. The state transition logic is that once the power grid or photovoltaic power generation is detected to be restored during the dormant standby phase, the system immediately exits the dormant standby state and switches to operating condition two to perform heating control relying on external energy.

[0081] Preferably, when operating under condition one and when the external energy supply is normal, the BMS module 9 controls the battery module 1 not to supply power to the heating film 5.

[0082] Preferably, the inverter 3 is connected to a load on the AC side. When in operating condition two, after the BMS module 9 controls the main circuit relay 2 to close, if the inverter 3 does not supply power to the heating film 5 and receives a power supply request from the load, it controls the auxiliary relay 7 to open, the heating control relay 4 to open, and the main circuit relay 2 to close to supply power to the load. After the load power supply ends, the heating control relay 4 is closed again.

[0083] Preferably, under operating condition three and with battery SOC ≥ 35%, to balance heating efficiency and battery life, the BMS module adjusts the temperature based on the cell temperature T and the preset target temperature T. ref Temperature difference ΔT = T ref Based on -T and the battery SOC, the average heating power P of the heating film 5 is calculated according to the following formula. avg :

[0084] P avg =P max ·min{1,k·ΔT+λ·(SOC−35%)},

[0085] Among them, P max The rated power of the electric heating film 5;

[0086] P avg For average heating power, 0 < P avg ≤Pmax ;

[0087] k is the temperature difference gain coefficient, which characterizes the intensity of the adjustment of heating power by the difference between the cell temperature and the target temperature, k > 0;

[0088] λ is the state-of-charge correction factor, which characterizes the degree of correction of the heating power by the remaining battery charge. λ > 0.

[0089] The BMS module is based on the duty cycle D=P avg / P max The heating control relay 4 is subjected to low-frequency periodic on / off control. Within a single control cycle, the on-time of the heating control relay 4 is D×T. cycle The disconnection duration is (1-D)×T cycle T cycle To preset the control cycle, so that the electric heating film 5 operates at an average power P avg Heat battery module 1; when the cell temperature T reaches T ref When the heating control relay 4 is disconnected, 0 < D ≤ 1.

[0090] According to one aspect of this application, a cryogenic heating control device for an energy storage system is provided.

[0091] Figure 2 This is a schematic diagram of the structure of a cryogenic heating control device for an energy storage system according to this application. Figure 2 As shown, the electronic device 500 is presented in the form of a general-purpose computing device. The components of the electronic device 500 may include, but are not limited to: at least one processing unit 510, at least one storage unit 520, a bus 530 connecting different platform components (including storage unit 520 and processing unit 510), a display unit 540, etc.

[0092] The storage unit stores program code, which can be executed by the processing unit 510, causing the processing unit 510 to perform the steps described above. For example, the processing unit 510 can execute... Figure 1 The steps are shown in the figure.

[0093] Storage unit 520 may include readable media in the form of volatile storage units, such as random access memory (RAM) 5201 and / or cache memory 5202, and may further include read-only memory (ROM) 5203.

[0094] Storage unit 520 may also include a program / utility 5204 having a set (at least one) program module 5205, such program module 5205 including but not limited to: operating system, one or more application programs, other program modules and program data, each or some combination of these examples may include an implementation of a network environment.

[0095] Bus 530 can represent one or more of several types of bus structures, including a memory cell bus or memory cell controller, a peripheral bus, a graphics acceleration port, a processing unit, or a local bus using any of the various bus structures.

[0096] Electronic device 500 can also communicate with one or more external devices 570 (e.g., keyboard, pointing device, Bluetooth device, etc.), and with one or more devices that enable a user to interact with electronic device 500, and / or with any device that enables electronic device 500 to communicate with one or more other computing devices (e.g., router, modem, etc.). This communication can be performed via input / output (I / O) interface 550. Furthermore, electronic device 500 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 560. Network adapter 560 can communicate with other modules of electronic device 500 via bus 530. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in conjunction with electronic device 500, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0097] According to one aspect of this application, a computer-readable storage medium is provided for storing a program that, when executed, implements the steps of the above-described method.

[0098] Figure 3 This is a schematic diagram of the structure of the computer-readable storage medium of this application. (Reference) Figure 3 As shown, a program product 600 for implementing the above-described method according to an embodiment of this application is described. It may employ a portable compact disc read-only memory (CD-ROM) and includes program code, which can run on a terminal device, such as a personal computer. However, the program product of this application is not limited thereto. In this document, a readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0099] The program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0100] Computer-readable storage media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable storage medium may also be any readable medium other than a readable storage medium that can transmit, propagate, or transfer a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0101] Program code for performing the operations of this application can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0102] In summary, the cryogenic heating system, control method, equipment, and storage medium of this energy storage system, through a circuit topology design in which the heating circuit is connected in parallel to the DC side of the inverter, combined with a multi-condition differentiated control strategy based on cell temperature, external energy operating status, and battery state of charge, can achieve intelligent coordinated scheduling of external energy sources such as the grid and photovoltaics with battery energy. In scenarios where external energy supply is normal, external energy is prioritized for battery cryogenic heating, significantly reducing the frequency and depth of battery cryogenic discharge, mitigating cell polarization and capacity decay caused by cryogenic discharge, and effectively extending the cycle life of the energy storage battery. Simultaneously, by setting graded state of charge thresholds to constrain the activation and deactivation of battery self-heating, the battery maintains a high-charge standby state under normal operating conditions, fully guaranteeing backup power supply capacity in extreme scenarios such as grid failures and photovoltaic power outages, and improving the overall operational reliability of the system.

[0103] In addition, relying on the combination of current-limiting anti-reverse branches at both ends of the main circuit and the low-power sleep standby mechanism, the system can retain basic monitoring and control power in extreme fault scenarios such as low temperature, external energy interruption, and low charge state superposition. After the external energy supply is restored, it will automatically trigger heating and gradually restore the normal charging and discharging operation of the system. No on-site manual reset is required throughout the process, which significantly reduces the operation and maintenance cost and equipment downtime loss of energy storage systems in high-altitude and cold regions.

[0104] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this application, and all such modifications or substitutions should be considered within the scope of protection of this application.

Claims

1. A low-temperature heating system for an energy storage system, characterized in that, include: A main circuit is formed by connecting a battery module, a main circuit relay, and an inverter in series. The positive terminal of the battery module is connected to the positive DC terminal of the inverter, and the negative terminal of the battery module is connected to the negative DC terminal of the inverter. The inverter is connected to an external energy source. A heating circuit is provided, with one end of the heating circuit connected between the positive DC terminal of the inverter and the main circuit relay, and the other end connected in series with a heating control relay and an electric heating film and then connected to the negative terminal of the battery module. A current-limiting anti-reverse branch is formed by a reverse protection diode, an auxiliary relay, and a current-limiting resistor connected in series, and the current-limiting anti-reverse branch is connected in parallel across the two ends of the main circuit relay; A BMS module is used to collect data in real time on the cell temperature T, battery SOC, main circuit current I, and the power supply status of the external energy source of the battery module; based on the cell temperature T, battery SOC, main circuit current I, and the power supply status of the external energy source, it controls the opening and closing of the main circuit relay, heating control relay, and auxiliary relay to control the power supply of the electrothermal film to heat the battery module.

2. The heating system according to claim 1, characterized in that, The auxiliary relay closes when the temperature of the battery module is below 0°C and the electrothermal film is powered by the external energy source, and opens when the main circuit relay closes. When the auxiliary relay is closed, the current-limiting anti-reverse branch provides the inverter with a detectable voltage signal of the battery module through the current-limiting resistor.

3. The heating system according to claim 1, characterized in that, The external energy source includes a photovoltaic system and a public power grid. The photovoltaic system is connected to the DC side of the inverter, and the public power grid is connected to the AC side of the inverter.

4. A method for controlling low-temperature heating in an energy storage system, characterized in that, The control method, applied to the heating system according to any one of claims 1 to 3, comprises: The BMS module collects the cell temperature T, battery SOC, main circuit current I, and power supply status of the external energy source in real time. Based on the cell temperature T, battery SOC, main circuit current I, and power supply status of the external energy source, it controls the opening and closing of the main circuit relay, heating control relay, and auxiliary relay to control the power supply of the heating film to heat the battery module.

5. The control method according to claim 4, characterized in that, It also includes the following steps: The BMS module has four preset operating conditions for the battery module built in: Operating condition 1: The cell temperature T ∈ [0℃, 10℃); Operating Condition 2: The cell temperature T < 0℃, and the external energy source is supplying power normally; Operating Condition 3: The cell temperature T < 0℃, the external energy source is not supplying power, and the battery SOC > 5%; Operating Condition 4: The cell temperature T < 0℃, the external energy source does not supply power, and the battery SOC ≤ 5%; When the BMS module determines that it is in operating condition one, it controls the heating control relay to close, the auxiliary relay to open, and the main circuit relay to maintain its current state; when the cell temperature T≥15℃, the BMS module controls the heating control relay to open. When the BMS module determines that it is in operating condition two, it controls the heating control relay to close, the main circuit relay to open, and the auxiliary relay to close. When the cell temperature T≥5℃, it controls the main circuit relay to close, the auxiliary relay to open, and continues to heat the battery module through the heating control relay until the cell temperature T≥15℃, at which point the heating control relay is disconnected. When the BMS module determines that it is in operating condition three, if the battery SOC is ≥ 35%, it controls the main circuit relay to close, the auxiliary relay to open, and the heating control relay to close; if the battery SOC is ∈ (5%, 35%), it controls the main circuit relay to close, the auxiliary relay to open, and the heating control relay to open. When the BMS module determines that it is in operating condition four, it controls the main circuit relay, heating control relay and auxiliary relay to disconnect, and the energy storage system enters a hibernation standby state.

6. The control method according to claim 5, characterized in that, When operating under condition one and the external energy source is supplying power normally, the BMS module controls the battery module not to supply power to the heating film.

7. The control method according to claim 5, characterized in that, The inverter is connected to a load on its AC side. When operating under condition two, after the BMS module controls the main circuit relay to close, if the inverter does not supply power to the heating film and receives a power supply request from the load, it controls the auxiliary relay to open, the heating control relay to open, and the main circuit relay to close to supply power to the load. After the load is powered, the heating control relay is closed again.

8. The control method according to claim 5, characterized in that, Under operating condition three and when the battery SOC ≥ 35%, the BMS module determines the battery cell temperature T based on the preset target temperature T. ref Temperature difference ΔT = T ref -T and the battery SOC, the average heating power P of the electrothermal film is calculated according to the following formula. avg : P avg =P max ×min{1,k×ΔT+λ×(SOC−35%)}, Among them, P max The rated power of the electrothermal film; P avg For average heating power, 0 < P avg ≤P max ; k is the temperature difference gain coefficient, k > 0; λ is the state of charge correction factor, λ > 0; The BMS module is based on a duty cycle D=P avg / P max The heating control relay is subjected to low-frequency periodic on / off control. Within a single control cycle, the on-time of the heating control relay is D×T. cycle The disconnection duration is (1-D)×T cycle T cycle To preset the control cycle, so that the electrothermal film operates at an average power P avg The battery module is heated; when the cell temperature T reaches T... ref When the heating control relay is disconnected, 0 < D ≤ 1.

9. A low-temperature heating control device for an energy storage system, characterized in that, include: processor; A memory in which executable instructions of the processor are stored; The processor is configured to execute the steps of the cryogenic heating control method for the energy storage system according to any one of claims 4-8 by executing the executable instructions.

10. A computer-readable storage medium for storing a program, characterized in that, When the program is executed, it implements the steps of the low-temperature heating control method for the energy storage system according to any one of claims 4-8.

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