Energy storage power station safety management system for realizing thermal runaway grading early warning based on flame-retardant foaming

Abstract

The invention discloses an energy storage power station safety management system capable of realizing thermal runaway grading early warning based on flame-retardant foaming, which is characterized in that a battery module is quickly wrapped and isolated from oxygen by controlling refrigerant spraying and triggering a foaming device to start, a large amount of high-temperature-resistant flame-retardant foaming agent is quickly released, and the thermal runaway grading early warning is realized by combining the refrigerant spraying with a foaming material. The further spreading risk of thermal runaway of the battery module is avoided, and safety management of the energy storage power station is achieved. By controlling the valves, switching of different operation modes can be achieved, and safety management of graded early warning of thermal runaway of the energy storage power station is achieved. According to the system, two stages of grading early warning stages are set for the battery of the energy storage power station, a battery cooling operation mode of the second-stage early warning stage and a battery thermal runaway blocking mode in the first-stage early warning mode are achieved, the battery operation temperature can be reasonably regulated and controlled, the battery operation efficiency is improved, and the energy storage power station is protected. And the risk propagation of thermal runaway of the battery is effectively blocked.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage power stations, relates to the thermal management safety operation of electrochemical energy storage power stations and thermal runaway early warning protection of energy storage batteries, and is a safety management system for energy storage power stations that realizes thermal runaway graded early warning based on flame retardant foaming. Background Art

[0002] Electrochemical energy storage power station systems can achieve rapid charging and discharging, and respond quickly to demand, and are suitable for load regulation and frequency regulation of power grids. In addition, energy storage power stations can flexibly increase or decrease energy storage capacity according to demand to adapt to applications of different scales. However, safety issues of energy storage batteries, such as overcharging, over-discharging, short circuits, and other faults, can cause thermal runaway safety hazards such as battery overheating, fire, and even explosion. Thermal safety issues are the biggest factor limiting the further development of battery energy storage systems. If thermal runaway events in local batteries in a battery pack are out of control, they will spread to batteries in surrounding areas, causing uncontrollable hazards. Therefore, battery thermal management methods that can effectively suppress thermal runaway are particularly important.

[0003] At present, the existing battery thermal management technologies mainly include air cooling, liquid cooling, phase change material cooling, composite cooling, etc. They are different in working principle, equipment installation, temperature control, temperature balance, operation and maintenance, etc. They can provide basic heat dissipation support in some application scenarios, but these thermal management technologies cannot effectively deal with potential thermal runaway problems when facing high power density, complex working conditions or extreme environments. Therefore, how to achieve safe and efficient management of battery thermal management warnings for energy storage power stations is a technical problem that needs to be solved urgently. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to propose a safety management system for energy storage power stations based on flame-retardant foaming to achieve graded early warning of thermal runaway, mainly to solve the problem that the battery cannot effectively block the spread of thermal runaway phenomena such as overheating and combustion.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A safety management system for an energy storage power station based on flame-retardant foaming to achieve graded early warning of thermal runaway, wherein the battery pack of the energy storage power station is divided into a plurality of battery modules, the temperature of each battery module is measured by a temperature sensor, and the measured temperature signal is transmitted to a control center; the safety management system comprises a compressor circuit, a direct cooling plate branch, a spray branch, and a plurality of valves, the compressor circuit is used to generate a refrigerant liquid, the direct cooling plate branch and the spray branch are connected in parallel to the refrigerant liquid pipeline of the compressor circuit; the direct cooling plate branch comprises a direct cooling plate arranged at the top of the battery module and a foaming device at the bottom, respectively, and the spray branch comprises a spray head arranged between the direct cooling plate and the battery module;

[0007] The safety management system sets a first - level temperature warning value T1 and a second - level temperature warning value T2; according to the temperature Tt measured by the temperature sensor, the safety management system executes the following modes:

[0008] When Tt < T2, control the valve to make the refrigerant working medium flow only in the compressor circuit;

[0009] When T2 < Tt < T1, control the valve to make the refrigerant working medium flow in the compressor circuit and the direct - cooling plate branch, and cool the corresponding battery module through the direct - cooling plate;

[0010] When Tt > T1, control the valve to make the refrigerant working medium flow in the compressor circuit and the spray branch, spray the refrigerant liquid to the corresponding battery module through the spray head, and at the same time control the foaming device of the corresponding battery module to release the flame - retardant foaming material.

[0011] In one embodiment, the compressor circuit includes a compressor, a condenser, a liquid storage tank, an expansion valve, an evaporator, an evaporation pressure regulating valve, a gas - liquid separator, and a drying filter; a three - way valve one is arranged between the expansion valve and the evaporator, a three - way valve two is arranged between the evaporation pressure regulating valve and the gas - liquid separator, the direct - cooling plate branch and the spray branch are in parallel pipelines through a three - way valve three and a three - way valve four, and are in parallel pipelines with the compressor circuit through the three - way valve one and the three - way valve two.

[0012] In one embodiment, the three - way valve one, the three - way valve two, the three - way valve three, and the three - way valve four are all proportional - integral regulating valves.

[0013] In one embodiment, the A port of the three - way valve one is connected to the outlet of the expansion valve, the B port is connected to the inlet of the evaporator, and the C port is connected to the A port of the three - way valve three; the A port of the three - way valve two is connected to the inlet of the gas - liquid separator, the B port is connected to the outlet of the evaporation pressure regulating valve, and the C port is connected to the A port of the three - way valve four; the B port of the three - way valve three is connected to the inlet of the direct - cooling plate branch, and the C port is connected to the inlet of the spray branch; the B port of the three - way valve four is connected to the outlet of the direct - cooling plate branch, and the C port is connected to the outlet of the spray branch.

[0014] In one embodiment, the direct - cooling plate is a flat plate with multiple fluid channels inside, exchanges heat with a two - phase refrigerant as the medium, and the refrigerant is evenly distributed in the fluid channels to achieve uniform heat exchange with the battery module.

[0015] In one embodiment, the foaming device includes a cylinder body, a nozzle, and a powder spray head. The cylinder body stores the flame - retardant foaming material. The device is controlled by an electromagnetic valve. The nozzle is a pressure - type nozzle and works through an electromagnetic valve, a control unit, and a power supply module.

[0016] In one embodiment, the power module provides a stable power supply for the solenoid valve and the control unit. The power module and the control unit are located in a control center. The control unit uses a microcontroller to receive electrical signals and control the opening and closing of the solenoid valve.

[0017] In one embodiment, the foaming device is arranged at the bottom of the battery module, and the nozzle outlet thereof is located in the mold shell of the battery module.

[0018] In one embodiment, each of the battery modules has a plurality of single cells, and each single cell is provided with a temperature sensor. In each of the battery modules, the highest detection value of each temperature sensor is used as the temperature Tt.

[0019] In one embodiment, the temperature sensor is arranged at a cell tab of each single battery.

[0020] Compared with the prior art, the present invention realizes cooling of the battery module and blocking of potential thermal runaway through the reasonable arrangement of the evaporator pressure regulating valve, three-way valve, foaming device, etc., and realizes thermal safety management of the electrochemical energy storage system with different strategies under different working conditions through the monitoring and regulation of various sensors. More importantly, it blocks potential thermal runaway. The operating efficiency of the energy storage battery is improved, and the risk of thermal runaway of the energy storage power station is effectively alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the energy storage power station safety management system of the present invention that realizes thermal runaway graded early warning based on flame retardant foaming.

[0022] Figure 2 It is a schematic structural diagram of three-way valve 1 and three-way valve 3 of the present invention.

[0023] Figure 3 It is a schematic diagram of the structure of the three-way valve 2 and the three-way valve 4 of the present invention.

[0024] Figure 4 It is a schematic diagram of the foaming device of the present invention.

[0025] In the figure: 1- compressor; 2- condenser; 3- liquid storage tank; 4- expansion valve; 5- three-way valve one; 6- evaporator; 7- evaporation pressure regulating valve; 8- three-way valve two; 9- gas-liquid separator; 10- drying filter; 11- three-way valve three; 12- direct cooling plate; 13- three-way valve four; 14- spray pipe; 15- spray head; 16- battery module; 17- battery cell; 18- temperature sensor; 19- foaming device; 20- control center; 21- solenoid valve 22- cylinder; 23- nozzle; 24- powder nozzle. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the specific implementation manners in conjunction with the accompanying drawings.

[0027] As Figure 1 shown, the present invention is a safety management system for an energy storage power station that realizes thermal runaway hierarchical early warning based on flame-retardant foaming. In the energy storage power station, the battery packs are divided into multiple battery modules 16. Figure 1 In the figure, the battery pack is divided into 4 battery modules 16. A temperature sensor 18 is equipped for each battery module 16 to measure its temperature, and the measured temperature signal is transmitted to the control center 20. The control center 20 performs protection actions according to different real-time temperature measurement values. Traditional protection actions are generally based on a single threshold, which is difficult to meet the actual requirements of high power density, complex working conditions or extreme environments.

[0028] Therefore, the safety management system of the present invention designs a compressor circuit, a direct cooling plate branch and a spraying branch, and performs different actions by switching valves and combining different threshold conditions.

[0029] Specifically, the compressor circuit utilizes the circulation of the refrigerant working medium. The refrigerant working medium switches between the refrigerant gas and the refrigerant liquid, and is mainly used to provide the refrigerant liquid for the direct cooling plate branch and the spraying branch in the present invention. The direct cooling plate branch and the spraying branch are connected in parallel to the refrigerant liquid pipeline of the compressor circuit, and the flow direction of the refrigerant liquid to the direct cooling plate branch and / or the spraying branch can be controlled by valves.

[0030] In the present invention, the direct cooling plate branch mainly includes a direct cooling plate 12 and a foaming device 19. The direct cooling plate 12 is located at the top of the battery module 16 and can cool the battery module 16 through heat exchange when the refrigerant liquid is introduced. The foaming device 19 is located at the bottom of the battery module 16 and can quickly spray and release the flame-retardant foaming material to the battery module 16 when it is started.

[0031] In the present invention, the spraying branch includes a spraying pipeline 14 and a spraying head 15. The spraying head 15 is installed on the spraying pipeline 14 and faces the battery module 16. Preferably, the spraying head 15 is located between the direct cooling plate 12 and the battery module 16.

[0032] The safety management system of the present invention sets two thresholds, namely the first-level temperature early warning value T1 and the second-level temperature early warning value T2. According to the real-time temperature Tt measured by the temperature sensor 18, the safety management system of the present invention executes the following modes:

[0033] Normal temperature operation mode: Tt < T2. At this time, the system operates normally, and the control valve is used to make the refrigerant working medium flow only in the compressor circuit, and there is no need to cool the battery module 16.

[0034] Secondary warning cooling mode: T2 < Tt < T1. At this time, the system has a certain high-temperature risk and needs to be intervened. Specifically, it refers to the heat dissipation stage of heat dissipation. The control valve enables the refrigerant working medium to flow in the compressor circuit and the direct cooling plate branch. The refrigerant working medium is sent into the direct cooling plate 12 and only cools the corresponding battery module 16 through the direct cooling plate 12.

[0035] Primary warning blocking mode: Tt > T1. At this time, the system has an urgent high-temperature risk and needs to be strongly intervened. Specifically, it refers to the fire-fighting stage of spraying and foaming the thermally out-of-control battery. The control valve enables the refrigerant working medium to flow in the compressor circuit and the spray branch. The refrigerant working medium is sent into the spray pipeline 14, and the refrigerant liquid is sprayed onto the corresponding battery module 16 through the spray head 15 to cool it strongly. At the same time, the foaming device 19 of the corresponding battery module 16 is controlled to release the flame-retardant foaming material to wrap the battery module 16 to isolate oxygen, and the spread of combustion and other thermal runaway is blocked through the combination of refrigerant spraying and foaming material.

[0036] The system of the present invention can realize the switching of different operation modes through the control of the valve, and realize the safety management of the hierarchical early warning of thermal runaway in the energy storage power station. By setting two levels of hierarchical early warning stages for the batteries in the energy storage power station, the battery cooling operation mode in the secondary warning stage and the battery thermal runaway blocking mode in the primary warning mode are realized. The battery operating temperature can be reasonably regulated, the battery operating efficiency can be improved, and the risk propagation of battery thermal runaway can be effectively blocked.

[0037] According to the above system management method, the present invention realizes the heat safety management of different strategies under different working conditions, and can block the potential thermal runaway by combining refrigerant spraying and foaming materials, greatly reducing the thermal runaway risk of the energy storage power station.

[0038] In a further embodiment of the present invention, refer to Figure 1 、 Figure 2 and Figure 3The compressor circuit includes a compressor 1, a condenser 2, a liquid storage tank 3, an expansion valve 4, an evaporator 6, an evaporation pressure regulating valve 7, a gas-liquid separator 9 and a drying filter 10. The three-way valve 1 5 is arranged between the expansion valve 4 and the evaporator 6, and the three-way valve 2 8 is arranged between the evaporation pressure regulating valve 7 and the gas-liquid separator 9. The direct cooling plate branch and the spray branch are connected in parallel through the three-way valve 3 11 and the three-way valve 4 13, and are connected in parallel with the compressor circuit through the three-way valve 1 5 and the three-way valve 2 8. Specifically, the outlet of compressor 1 is connected to the inlet of condenser 2, the inlet of condenser 2 is connected to the inlet of liquid storage tank 3, the outlet of liquid storage tank 3 is connected to the inlet of expansion valve 4, the outlet of expansion valve 4 is connected to port A of three-way valve 5, port B of three-way valve 5 is connected to the inlet of evaporator 6, the outlet of evaporator 6 is connected to the inlet of evaporation pressure regulating valve 7, the outlet of evaporation pressure regulating valve 7 is connected to port B of three-way valve 8, port A of three-way valve 8 is connected to the inlet of gas-liquid separator 9, the outlet of gas-liquid separator 9 is connected to the inlet of drying filter 10, and the inlet of drying filter 10 is connected to the inlet of compressor 1. The A port of three-way valve three 11 is connected to the C port of three-way valve one 5, the B port of three-way valve three 11 is connected to the inlet of direct cooling plate 12, the outlet of direct cooling plate 12 is connected to the B port of three-way valve four 13, the A port of three-way valve four 13 is connected to the C port of three-way valve two 8, the C port of three-way valve three 11 is connected to the inlet of spray pipe 14, and the outlet of spray pipe 14 is connected to the C port of three-way valve four 13.

[0039] Each three-way valve of the present invention is an electronic regulating valve, for example, a proportional-integral regulating valve, typically a VB7000 series electric three-way valve, which can adjust the passage through an electronic control method to meet automation requirements.

[0040] In combination with the above compressor circuit, three modes of the present invention are further described as follows:

[0041] 1. Normal temperature operation mode of the system: When the energy storage power station is running, the temperature Tt measured by the temperature sensor 18 is less than the system secondary warning temperature T2, and the system starts the normal temperature operation mode. At this time, the control center controls the A and B ports of the three-way valve 1 5 to open, and the C port to close; the A and B ports of the three-way valve 2 8 to open, and the C port to close.

[0042] The specific cycle process is as follows: the refrigerant flows out from the outlet of the compressor 1, passes through the condenser 2, the liquid storage tank 3, the expansion valve 4, the three-way valve 1 5, the evaporator 6, the evaporation pressure regulating valve 7, the three-way valve 2 8, the gas-liquid separator 9, the drying filter 10, and finally returns to the compressor 1 to complete the cycle.

[0043] The circulation principle is as follows: low-temperature and low-pressure refrigerant gas is compressed by compressor 1 to become high-temperature and high-pressure refrigerant gas, and high-temperature and high-pressure refrigerant gas is converted into low-pressure refrigerant liquid with a certain temperature through condenser 2, and flows through liquid storage tank 3, which is used to store refrigerant liquid, balance system pressure, and adjust the refrigerant flow in the system cycle. The refrigerant liquid flowing out of liquid storage tank 3 is converted into low-temperature and low-pressure refrigerant liquid through expansion valve 4, and then flows through evaporator 6 to become low-temperature and low-pressure refrigerant gas, and the refrigerant is separated into gas and liquid through gas-liquid separator 9, and then passes through drying filter 10 to ensure that the refrigerant flowing into compressor 1 is gas, and finally flows into the compressor to realize circulation.

[0044] 2. System secondary warning cooling mode: When the energy storage power station is running, the system secondary warning temperature T2 < the temperature Tt measured by the temperature sensor 18 < the system primary warning temperature T1, and the system starts the secondary warning cooling mode. At this time, the A port, B port and C port of the three-way valve 1 5 are open; the A port, B port and C port of the three-way valve 2 8 are open. The refrigerant flows in parallel in the compressor circuit and the direct cooling plate circuit.

[0045] The specific cycle process is as follows: the refrigerant flows out from the outlet of the compressor 1, passes through the condenser 2, the liquid storage tank 3, the expansion valve 4, the A and B ports of the three-way valve 1 5, the evaporator 6, the evaporation pressure regulating valve 7, and the A and B ports of the three-way valve 2 8 in sequence. After passing through the three-way valve 1 5, the refrigerant is divided into two paths. One path flows through the gas-liquid separator 9 and the drying filter 10, and finally returns to the compressor 1 to complete the compressor loop cycle. The other path of refrigerant flows through the B port of the three-way valve 3 11, the direct cooling plate 12, and the B port of the three-way valve 4 13 to complete the direct cooling plate branch cycle.

[0046] The circulation principle is as follows: low-temperature and low-pressure refrigerant gas is compressed by compressor 1 to become high-temperature and high-pressure refrigerant gas, and high-temperature and high-pressure refrigerant gas is converted into low-pressure refrigerant liquid with a certain temperature through condenser 2, and flows through liquid storage tank 3, which is used to store refrigerant liquid, balance system pressure, and adjust the refrigerant flow in the system cycle. The refrigerant liquid flowing out of the liquid storage tank is converted into low-temperature and low-pressure refrigerant liquid through expansion valve 4, and the refrigerant is divided into two paths after flowing through three-way valve 1 5. One path flows through evaporator 6 to become low-temperature and low-pressure refrigerant gas, and the gas-liquid separator 9 separates the refrigerant gas and liquid, and then passes through drying filter 10 to ensure that the refrigerant flowing into the compressor is gas, and finally flows into compressor 1 to realize the compressor 1 and compressor loop circulation. The other path of refrigerant flows through direct cooling plate 12, at which time the low-temperature and low-pressure refrigerant liquid absorbs the heat generated during the operation of the battery, so that the battery temperature drops to a suitable working range, and finally the refrigerant converges at three-way valve 2 8 to realize the direct cooling plate branch circulation.

[0047] 3. System level 1 warning blocking mode: When the energy storage power station is running, the temperature Tt measured by the temperature sensor 18> the system level 1 warning temperature T1, and the system starts the level 1 warning blocking mode. At this time, the B ports of the three-way valve 1 5, the three-way valve 2 8, the three-way valve 3 11 and the three-way valve 4 13 are all disconnected, and the C ports of the three-way valve 3 11 and the three-way valve 4 13 are opened, and the refrigerant is released directly through the spray pipe 14 and the spray head 15. At the same time, the temperature signal measured by the temperature sensor 18 is transmitted to the control center 20, and the control center 20 sends a start device command to the foaming device 19. The foaming device 19 quickly releases the high-temperature resistant foaming material to wrap the battery module, isolate oxygen, and block the propagation of thermal runaway such as combustion.

[0048] The specific working process is as follows: the battery temperature Tt measured by the temperature sensor 18 exceeds the system's first-level warning temperature value T1, the control center 20 receives the temperature signal sent by the temperature sensor 18, and sends a start device command to the foaming device 19. The foaming device 19 immediately and quickly releases the high-temperature resistant flame-retardant foaming agent, which quickly foams to wrap the battery module 16 and isolate it from oxygen, and blocks the propagation of thermal runaway such as combustion through the combination of refrigerant spraying and foaming materials.

[0049] In a further embodiment of the present invention, the direct cooling plate 12 is a flat plate with multiple fluid channels therein, and uses a two-phase refrigerant as a medium for heat exchange. The two-phase refrigerant can be evenly distributed in the fluid channel, so as to achieve uniform heat exchange with the top surface of the battery module 16. The distance between the direct cooling plate 12 and the battery module 16 is designed according to the actual space and the expected heat generation of the battery, the cold flow rate that the direct cooling plate 12 can provide, etc. The main material of the direct cooling plate 12 is a metal material with high thermal conductivity (such as copper or aluminum). Its main function is to quickly conduct the heat generated by the battery module 16. Multiple flow channels are designed in the flat plate, and the shape of the flow channels can be parallel, staggered or microchannel structures. The diameter and direction of the flow channel are optimized to reduce the flow resistance and improve the heat exchange efficiency of the fluid.

[0050] In a further embodiment of the present invention, reference Figure 1 and Figure 4 , the foaming device 19 can be set at the bottom of the battery module 16. By reading the conditional trigger signal of the control center 20, when the measured temperature exceeds the system's first-level warning temperature, the foaming device 19 is triggered to start releasing the foaming material such as a B1-level flame-retardant and fire-proof polyurethane foaming agent. The foaming material can achieve rapid release and structural shaping as well as high temperature resistance. Structurally, the foaming device 19 mainly includes a barrel 22, a nozzle 23 and a powder nozzle 24. The outlet of the nozzle 23 is located in the mold shell of the battery module 16. The barrel 22 is used to store flame-retardant foaming materials. The overall operation of the device is controlled by a solenoid valve 21. Multiple foaming devices 19 can share one solenoid valve 21, or each foaming device 19 can be provided with one solenoid valve 21. The solenoid valve 21 can be, for example, a 2 / 2 valve or a 3 / 2 valve.

[0051] The nozzle 23 of the foaming device 19 of the present invention is a pressure type nozzle, which works through the solenoid valve 21, the control unit, and the power module. Specifically, the power module provides a stable power supply for the solenoid valve 21 and the control unit. The power module and the control unit are located in the control center 20. The control unit uses a microcontroller (such as a single chip microcomputer or Arduino) to receive electrical signals and control the opening and closing of the solenoid valve 21. The specific working principle is that the control unit receives the electrical signal from the temperature sensor 18, and then analyzes the input signal according to the preset logic (the designed temperature threshold, the system first-level warning temperature value) to decide whether to open the nozzle 23. If the control unit decides to open the nozzle 23, it will send a control signal (such as a high-level signal) to the solenoid valve 21. The electromagnetic coil inside the solenoid valve 21 is activated to generate a magnetic field, thereby pushing the valve core to move and open the valve. If the nozzle needs to be closed, the control unit sends a low-level signal, the solenoid valve 21 releases the current, and the valve core returns to the closed state under the action of the spring. When the solenoid valve 21 is controlled to open, the stored foaming material will be released through the nozzle 23.

[0052] In a further embodiment of the present invention, each battery module 16 has a plurality of single batteries 17. Figure 1 In the structure shown, each battery module 16 has four single cells 17. In the present invention, each single cell 17 is preferably equipped with a temperature sensor 18, which can be arranged at the cell tab of each single cell 17 to detect the temperature of the battery cells 17 in the battery module 16. In each battery module 16, the highest detection value of each temperature sensor 18 is used as the temperature Tt, that is, the highest temperature of a single single cell 17 is used as the measured temperature of the battery module 16 to which it belongs.

[0053] In summary, the energy storage power station safety management system of the present invention, which realizes graded early warning of thermal runaway based on flame retardant foaming, uses sensors to monitor battery modules, and switches the system between different modes through the control center to realize the normal operation of the battery module. In addition, the system is provided with a first-level early warning mode. When the battery temperature is too high and thermal runaway is about to occur, the control center controls the refrigerant spray and the foaming device to start, and quickly releases a large amount of high-temperature resistant flame retardant foaming agent to quickly wrap the battery module and isolate it from oxygen. The combination of refrigerant spray and foaming material can avoid the risk of further spread of thermal runaway of the battery module. The entire safety management system is simple in structure and easy to maintain. It can realize the operating status of the battery module at different temperatures, and can effectively warn and handle potential thermal runaway during operation, thereby extending the operation stability and efficiency of the energy storage power station.

Claims

1. A safety management system for an energy storage power station based on flame retardant foaming to achieve graded early warning of thermal runaway, wherein the battery pack of the energy storage power station is divided into a plurality of battery modules (16), the temperature of each battery module (16) is measured by a temperature sensor (18), and the measured temperature signal is transmitted to a control center (20); characterized in that: The safety management system includes a compressor circuit, a direct cooling plate branch, a spray branch, and several valves. The compressor circuit is used to generate refrigerant liquid, and the direct cooling plate branch and the spray branch are connected in parallel to the refrigerant liquid pipeline of the compressor circuit. The direct cooling plate branch includes a direct cooling plate (12) arranged at the top of the battery module (16) and a foaming device (19) arranged at the bottom. The spray branch includes a spray head (15) arranged between the direct cooling plate (12) and the battery module (16). The safety management system sets a first-level temperature warning value T1 and a second-level temperature warning value T2. According to the temperature Tt measured by the temperature sensor (18), the safety management system executes the following modes: When Tt < T2, control the valves to make the refrigerant working medium flow only in the compressor circuit. When T2 < Tt < T1, control the valves to make the refrigerant working medium flow in the compressor circuit and the direct cooling plate branch, and cool the corresponding battery module (16) through the direct cooling plate (12). When Tt > T1, control the valves to make the refrigerant working medium flow in the compressor circuit and the spray branch, spray the refrigerant liquid to the corresponding battery module (16) through the spray head (15), and at the same time control the foaming device (19) of the corresponding battery module (16) to release the flame-retardant foaming material.

2. According to claim 1, the energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning is characterized in that: The compressor circuit includes a compressor (1), a condenser (2), a liquid storage tank (3), an expansion valve (4), an evaporator (6), an evaporation pressure regulating valve (7), a gas-liquid separator (9), and a drying filter (10). A three-way valve one (5) is arranged between the expansion valve (4) and the evaporator (6), and a three-way valve two (8) is arranged between the evaporation pressure regulating valve (7) and the gas-liquid separator (9). The direct cooling plate branch and the spray branch are connected in parallel through a three-way valve three (11) and a three-way valve four (13), and are connected in parallel with the compressor circuit through the three-way valve one (5) and the three-way valve two (8).

3. According to claim 2, the energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning is characterized in that: The three-way valve one (5), the three-way valve two (8), the three-way valve three (11), and the three-way valve four (13) are all proportional-integral regulating valves.

4. The energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning according to claim 2 or 3, characterized in that: The A port of the three-way valve one (5) is connected to the outlet of the expansion valve (4), the B port is connected to the inlet of the evaporator (6), and the C port is connected to the A port of the three-way valve three (11). The A port of the three-way valve two (8) is connected to the inlet of the gas-liquid separator (9), the B port is connected to the outlet of the evaporation pressure regulating valve (7), and the C port is connected to the A port of the three-way valve four (13). The B port of the three-way valve three (11) is connected to the inlet of the direct cooling plate branch, and the C port is connected to the inlet of the spray branch. The B port of the three-way valve four (13) is connected to the outlet of the direct cooling plate branch, and the C port is connected to the outlet of the spray branch.

5. According to claim 1, the energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning is characterized in that: The direct cooling plate (12) is a flat plate with multiple fluid channels inside, exchanges heat with two-phase refrigerant as the medium, and the refrigerant is evenly distributed in the fluid channels to achieve uniform heat exchange with the battery module (16).

6. According to claim 1, the energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning is characterized in that: The foaming device (19) comprises a barrel (22), a nozzle (23) and a powder nozzle (24); the barrel (22) stores a flame retardant foaming material; the nozzle (23) is a pressure type nozzle and operates through a solenoid valve (21), a control unit and a power module.

7. The energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning according to claim 6, characterized in that: The power module provides a stable power supply for the solenoid valve (21) and the control unit. The power module and the control unit are located in the control center (20). The control unit uses a microcontroller to receive electrical signals and control the opening and closing of the solenoid valve (21).

8. The energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning according to claim 1, 6 or 7, characterized in that: The foaming device (19) is arranged at the bottom of the battery module (16). The outlet of the nozzle (23) is located inside the mold shell of the battery module (16).

9. According to claim 1, the energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning is characterized in that: Each of the battery modules (16) has a plurality of single cells (17), and each single cell (17) is provided with a temperature sensor (18). In each of the battery modules (16), the highest detection value of each temperature sensor (18) is used as the temperature Tt.

10. The energy storage power station safety management system based on flame retardant foaming to achieve thermal runaway graded warning according to claim 9, characterized in that: The temperature sensor (18) is arranged at the cell tab of each single battery (17).

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