Energy storage power station cooling explosion-proof system

Abstract

The application discloses an energy storage power station cooling explosion-proof system, comprising a closed shell, an immersed battery pack, a forced convection component and an explosion-proof structure. To solve the problems of local thermal runaway and air film resistance, a shape memory alloy flow guide grid is arranged at the inlet of the battery monomer cooling channel, the grid is expanded by phase change under heat to reduce fluid resistance, target cooling flow physical reconstruction distribution is realized; a piezoelectric ultrasonic transducer array is arranged on the inner wall of the cooling medium cavity, sound cavitation effect is induced by high-frequency sound waves, the vaporization adiabatic air film on the surface of the battery is stripped by cavitation microjet to restore direct physical heat transfer; an acoustic-electric conversion damping array is arranged above the transformer oil surface, the mechanical energy of the explosion shock wave is converted into electric energy by the piezoelectric effect and consumed, and the peak impact pressure is weakened in cooperation with the explosion-proof valve and the bursting disc. The application realizes active thermal management and precise target temperature control under extreme conditions.

Description

Technical Field

[0001] This invention relates to the field of thermal management and safety protection technology for energy storage power stations, specifically to a cooling explosion-proof system for energy storage power stations. Background Technology

[0002] With the development of the new energy industry, energy storage power stations, as the infrastructure for power grid peak shaving and frequency regulation, are being built on an ever-expanding scale. Energy storage power stations contain a large number of high-capacity battery cells, which generate significant heat during charging and discharging. To maintain the battery pack within a safe temperature range and prevent thermal runaway, a cooling and thermal management system is required for energy storage power stations.

[0003] In existing thermal management solutions for energy storage power stations, immersion liquid cooling systems typically employ a fixed flow channel structure, relying on pumps to drive the cooling medium to circulate between the channels of the battery modules. The system collects temperature data through sensors, and the control unit adjusts the pump's operating power based on the overall temperature status, changing the total flow rate of the main circulation to achieve forced convection cooling of the battery pack.

[0004] However, existing technologies suffer from fluid distribution imbalances when dealing with localized abnormal temperature rises in batteries. When an abnormal temperature rise occurs in a localized battery cell in an energy storage power station, traditional cooling systems increase the total system flow by boosting the power of the main pump in the control unit. Since the physical geometry of each battery cooling channel is fixed and the fluid resistance characteristics are immutable, the cooling medium still flows to all channels according to the original flow resistance distribution. This mechanism cannot change the local fluid resistance and cannot target the cooling medium to the abnormal battery area, resulting in a limited increase in convective heat transfer flow at localized high-temperature points, making it difficult to effectively curb heat accumulation in the early stages of localized abnormal temperature rises. Furthermore, when the surface temperature of a battery cell rises sharply, the immersion cooling medium may undergo film boiling on the battery surface, forming a vaporized adiabatic film. This film has extremely high thermal resistance, severely hindering direct physical heat transfer between the liquid cooling medium and the battery surface, causing further heat accumulation on the battery surface and accelerating the thermal runaway process. Furthermore, once a single battery cell experiences thermal runaway and triggers an internal explosion, the explosive shock wave released into the sealed casing will generate extremely high peak impact pressure in a very short time. If only mechanical explosion-proof valves and rupture discs are used for passive pressure relief, the inner wall of the casing may still withstand transient pressure exceeding the structural limits before the valves are activated, posing a risk of casing tearing. Summary of the Invention

[0005] To address the problems mentioned in the background art, this invention provides a cooling and explosion-proof system for an energy storage power station, comprising: a shell, a battery pack, a control unit, an oil pump, a heat exchange assembly, a rupture disc, an explosion-proof valve, a shape memory alloy flow guide grille, a piezoelectric ultrasonic transducer array, and an acoustic-electric conversion damping array. The shell is a sealed structure with normally closed ventilation openings. The shell internally defines a transformer oil storage area and a transformer oil cooling medium cavity, the storage area being filled with transformer oil. The battery pack consists of multiple battery cells connected in series, the entire battery pack being distributed within the transformer oil in the transformer oil cooling medium cavity, with the transformer oil directly contacting the external shell structure of the battery cells for heat exchange. The fluid extraction end of the oil pump is connected to the bottom of the transformer oil cooling medium cavity via an oil pipeline, and the fluid output end of the oil pump is connected to the fluid input end of the heat exchange assembly via the oil pipeline. The fluid output end of the heat exchange assembly... The end is connected to the top of the transformer oil cooling medium cavity through the oil pipeline. The shell, oil pump, heat exchange components and oil pipeline together form a forced convection circulation closed loop for the transformer oil. The rupture disc is set on the top structure of the shell, and the explosion-proof valve is set on the side wall or top structure of the shell. The acoustic-electric conversion damping array is arranged in the buffer space above the liquid surface of the transformer oil storage area. The shape memory alloy flow guide grid is set at the inlet of the cooling channel formed by each adjacent battery cell inside the transformer oil cooling medium cavity. The piezoelectric ultrasonic transducer array is fixedly set on the inner wall of the transformer oil cooling medium cavity.

[0006] Preferably, the energy storage power station cooling explosion-proof system further includes an insulating support, the battery cells are installed inside the insulating support, and the insulating support constructs multiple fluid isolation spaces between adjacent battery cells; the shape memory alloy flow guide grid is made of a temperature-sensitive shape memory alloy material, and the shape memory alloy flow guide grid has a set phase transformation critical temperature for the transformation from martensite to austenite; when the transformer oil temperature around the abnormally temperatured battery cell reaches the phase transformation critical temperature, the shape memory alloy flow guide grid located at the inlet of the fluid isolation space where the abnormally temperatured battery cell is located undergoes a phase transformation, changing from a first geometric contraction state to a second geometric expansion state; the local volumetric flow rate of the transformer oil flowing through each fluid isolation space is determined by the flow coefficient of the corresponding fluid isolation space, the effective fluid flow cross-sectional area of ​​the shape memory alloy flow guide grid, the total fluid pressure difference between the fluid input end at the bottom and the fluid output end at the top of the transformer oil cooling medium cavity, and the fluid density of the transformer oil.

[0007] Preferably, the energy storage power station cooling explosion-proof system further includes multiple temperature sensors and an oil pump relay. The signal output terminals of the multiple temperature sensors are electrically connected to the multi-channel analog-to-digital converter input terminal of the control unit. The control unit is used to calculate the temperature characteristic parameters fed back by each temperature sensor according to a set sampling period, and continuously calculate the temperature rise rate of the highest battery temperature in the system. When the control unit detects that the temperature rise rate of the highest battery temperature is greater than the set temperature rise rate limit threshold of 5℃ / s, the control unit sends an ultrasonic drive AC signal to the piezoelectric ultrasonic transducer array. The piezoelectric ultrasonic transducer array radiates high-frequency sound waves into the transformer oil. The sound energy density injected into the transformer oil by the piezoelectric ultrasonic transducer array is determined by the sound pressure amplitude excited by the high-frequency sound waves in the transformer oil, the fluid density of the transformer oil, and the sound wave propagation speed of the high-frequency sound waves in the transformer oil.

[0008] Preferably, the sound pressure amplitude generated by the high-frequency sound wave inside the transformer oil is greater than the cavitation threshold of the transformer oil. The high-frequency sound wave induces acoustic cavitation effect and generates cavitation bubbles in the high-temperature region on the outer surface of the battery cell. The cavitation bubbles undergo asymmetric collapse at the interface between the outer surface of the battery cell and the vaporized insulating gas film, generating microjets pointing towards the outer surface of the battery cell. The microjets penetrate and peel off the vaporized insulating gas film on the outer surface of the battery cell, allowing the liquid transformer oil to re-contact the outer surface of the battery cell through the peeled area of ​​the vaporized insulating gas film.

[0009] Preferably, the energy storage power station cooling explosion-proof system further includes a dissipation resistor, and the acoustic-electric conversion damping array is electrically connected to the external dissipation resistor; when the battery cell thermally runs away and generates gas and an explosion shock wave, the explosion shock wave propagates and acts on the acoustic-electric conversion damping array, and the acoustic-electric conversion damping array uses the piezoelectric effect to convert the mechanical energy of the explosion shock wave into electrical energy; the acoustic-electric conversion damping array transmits the electrical energy to the dissipation resistor, converts it into heat energy and consumes it, thereby weakening the peak pressure of the explosion shock wave reaching the inner wall of the shell.

[0010] Preferably, the energy storage power station cooling explosion-proof system further includes a thermally conductive silicone pad and a temperature sensor; the lower part of the battery cell is immersed in the transformer oil in the transformer oil cooling medium cavity, and the liquid level of the transformer oil is lower than the top area of ​​the battery cell; the thermally conductive silicone pad is attached to the side wall area of ​​the battery cell that is not immersed in the transformer oil, and the temperature sensor is disposed on the side surface of the thermally conductive silicone pad away from the battery cell, and the temperature sensor is located above the liquid level of the transformer oil in vertical height, without physical contact with the transformer oil.

[0011] Preferably, the control unit's memory contains multiple temperature control thresholds; the control unit extracts the current highest battery temperature inside the energy storage power station's cooling and explosion-proof system, and sends a pulse width modulation command or digital control command to the oil pump relay according to the numerical range of the highest battery temperature, thereby changing the input voltage at the motor end of the oil pump and adjusting the operating speed of the oil pump; when the highest battery temperature is greater than 65°C, the control unit sends a full-speed operation command to the oil pump relay and simultaneously sends an alarm trigger signal to the alarm.

[0012] Preferably, the energy storage power station cooling explosion-proof system further includes a double-layer sealing ring, an oil-resistant rubber gasket, a ceramic fiber flame-retardant layer, and a flame-retardant foam layer; the double-layer sealing ring and the oil-resistant rubber gasket are attached together and fill the joint gaps of the shell; the ceramic fiber flame-retardant layer is laid on the inner wall surface of the shell; the flame-retardant foam layer fills the buffer space above the transformer oil surface in the transformer oil storage area, and the flame-retardant foam layer covers the transformer oil surface and has a V-0 flame-retardant rating, blocking the direct contact path between the transformer oil and the internal gas. When the fluid pressure inside the shell reaches 0.15MPa to 0.2MPa, the explosion-proof valve opens, unidirectionally discharging gas to the outside of the shell and blocking the reverse entry of external gas and ignition source into the shell; when the fluid pressure inside the shell rises and exceeds 0.2MPa, the rupture disc ruptures, forming a large-section exhaust channel to release the high-pressure gas inside the shell to the outside.

[0013] Preferably, the energy storage power station cooling explosion-proof system further includes a main switch, a fire alarm linkage interface, a smoke detector, a flame detector, and an electric air valve; the electric air valve is located at the normally closed ventilation opening of the housing; when the control unit detects that the smoke concentration signal sent by the smoke detector reaches the smoke concentration limit threshold, or receives the flame characteristic signal sent by the flame detector, the control unit sends a disconnect command to the main switch to cut off the charging and discharging main circuit, sends a linkage trigger electrical signal to the fire alarm linkage interface, and outputs a control signal to the electric air valve, causing the electric air valve to close and seal the normally closed ventilation opening of the housing.

[0014] The present invention, by adopting the above technical solution, can bring the following beneficial effects:

[0015] 1. This invention sets a shape memory alloy flow guide grid at the inlet of the fluid isolation space. When the transformer oil temperature in the abnormal area reaches the critical phase change temperature, the shape memory alloy flow guide grid changes from a first geometric contraction state to a second geometric expansion state. By increasing the effective fluid flow cross-sectional area, the fluid resistance of the corresponding fluid isolation space is reduced, and the transformer oil in the transformer oil cooling medium cavity is guided to converge towards the area where the abnormal battery cell is located. This achieves a targeted cooling flow physical reconstruction and distribution effect without the need for external electrical control unit intervention.

[0016] 2. This invention involves setting a piezoelectric ultrasonic transducer array on the inner wall of the transformer oil cooling medium cavity. When the rate of temperature change exceeds the limit threshold, it radiates high-frequency sound waves with sound pressure amplitude exceeding the cavitation threshold. The acoustic cavitation effect induced by the high-frequency sound waves generates asymmetric collapsed cavitation bubbles at the interface of the adiabatic gas film. The directional micro-jet generated when the cavitation bubbles collapse physically penetrates and peels off the vaporized adiabatic gas film on the outer surface of the battery cell. This helps to disrupt the film boiling stagnation state and promote the active temperature control effect of restoring the direct physical heat transfer path of the liquid transformer oil.

[0017] 3. This invention deploys an acoustic-electric conversion damping array electrically connected to a dissipation resistor in the buffer space above the transformer oil level. When a battery cell experiences thermal runaway and releases an explosive shock wave into the sealed casing, the shock wave acts on the acoustic-electric conversion damping array. Utilizing the deformation characteristics of the piezoelectric material, part of the mechanical kinetic energy carried by the shock wave is converted into electrical energy. This electrical energy is then converted into heat energy and consumed through the dissipation resistor in the peripheral circuit. This provides auxiliary attenuation of the peak shock wave pressure reaching the inner wall of the casing before the mechanical valves release pressure, thus playing an auxiliary role in energy dissipation and explosion prevention. Attached Figure Description

[0018] Figure 1 This is a three-dimensional schematic diagram of the energy storage power station cooling explosion-proof system of the present invention;

[0019] Figure 2 This is a detailed diagram of the explosion-proof structure of the present invention;

[0020] Figure 3 This is a block diagram of the electrical control connection of the present invention;

[0021] Figure 4 This is the oil pump control logic diagram of the present invention;

[0022] Figure 5 This is a flowchart of the system operation of the present invention.

[0023] In the diagram: 1. Shell; 2. Transformer oil storage area; 3. Battery pack; 3-1. Battery cell; 4. Temperature sensor; 5. Control unit; 6. Oil pump; 7. Heat exchange assembly; 8. Oil pipeline; 9. Transformer oil cooling medium cavity; 10. Thermally conductive silicone pad; 11. Insulating support; 12. Double-layer sealing ring; 13. Oil-resistant rubber pad; 14. Rupture disc; 15. Ceramic fiber flame-retardant layer; 16. Flame-retardant foam layer; 17. Explosion-proof valve; 18. Oil pump relay; 19. Alarm; 20. Main switch; 21. Acousto-electric conversion damping array; 22. Shape memory alloy flow guide grid; 23. Piezoelectric ultrasonic transducer array. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] Please refer to Figure 1 and 3 This embodiment describes the overall composition and basic architecture of the cooling explosion-proof system of the energy storage power station. The cooling explosion-proof system of the energy storage power station includes: shell 1, battery pack 3, control unit 5, oil pump 6, heat exchange component 7, rupture disc 14, explosion-proof valve 17, shape memory alloy flow guide grid 22, piezoelectric ultrasonic transducer array 23 and acoustic-electric conversion damping array 21.

[0027] The housing 1 is a sealed structure with a normally closed ventilation port. The housing 1 defines a transformer oil storage area 2 and a transformer oil cooling medium cavity 9. The transformer oil storage area 2 is filled with transformer oil. The battery pack 3 is composed of multiple battery cells 3-1 connected in series. The battery pack 3 is partially submerged in the transformer oil in the transformer oil cooling medium cavity 9. The lower part of the battery cell 3-1 is submerged in the transformer oil. The liquid level of the transformer oil is lower than the top area of ​​the battery cell 3-1. The transformer oil directly contacts the external housing structure of the battery cell 3-1 for heat exchange.

[0028] The fluid extraction end of the oil pump 6 is connected to the bottom of the transformer oil cooling medium cavity 9 through the oil pipeline 8. The fluid output end of the oil pump 6 is connected to the fluid input end of the heat exchange component 7 through the oil pipeline 8. The fluid output end of the heat exchange component 7 is connected to the top of the transformer oil cooling medium cavity 9 through the oil pipeline 8. The shell 1, oil pump 6, heat exchange component 7 and oil pipeline 8 together form a forced convection circulation closed loop for transformer oil. After absorbing the heat from the battery cell 3-1, the transformer oil in the transformer oil cooling medium cavity 9 is extracted by the oil pump 6 and sent into the heat exchange component 7. The heat exchange component 7 discharges the absorbed heat to the external environment. The cooled transformer oil flows back to the transformer oil cooling medium cavity 9 along the oil pipeline 8 for repeated circulation.

[0029] The system's electrical control network is equipped with a 24V power supply module, a temperature sensor 4, a control unit 5, an oil pump relay 18, an alarm 19, and a main switch 20. The output terminal of the 24V power supply module is electrically connected to the power input terminal of the temperature sensor 4 and the power input terminal of the control unit 5, respectively. The 24V power supply module provides DC operating voltage. The temperature sensor 4 is attached to the side wall area of ​​the corresponding battery cell 3-1 that is not immersed in the transformer oil through a thermally conductive silicone pad 10. The temperature sensor 4 is located above the surface of the transformer oil in vertical height and does not have physical contact with the transformer oil. The thermally conductive silicone pad 10 fills the mechanical assembly gap between the battery cell 3-1 and the temperature sensor 4 to reduce contact thermal resistance. The signal output terminal of the temperature sensor 4 is electrically connected to the analog-to-digital conversion input terminal of the control unit 5.

[0030] The control signal output terminal of the control unit 5 is electrically connected to the signal input terminal of the oil pump relay 18, the trigger terminal of the alarm 19, and the control terminal of the main switch 20, respectively. The power supply output terminal of the oil pump relay 18 is electrically connected to the motor of the oil pump 6. The control unit 5 collects the real-time temperature signals fed back by each temperature sensor 4 and outputs a pulse width modulation command or a digital control command to the oil pump relay 18. The control unit 5 adjusts the working state of the oil pump 6 through the pulse width modulation command or the digital control command. The control unit 5 sends an alarm trigger signal to the alarm 19 and sends a disconnect command to the main switch 20 to cut off the charging and discharging main circuit.

[0031] A rupture disc 14 is disposed on the top structure of the housing 1, an explosion-proof valve 17 is disposed on the side wall or top structure of the housing 1, an acoustic-electric conversion damping array 21 is arranged in the buffer space above the liquid surface of the transformer oil storage area 2, a shape memory alloy flow guide grille 22 is disposed at the inlet of the cooling channel formed by each adjacent battery cell 3-1 inside the transformer oil cooling medium cavity 9, and a piezoelectric ultrasonic transducer array 23 is fixedly disposed on the inner wall of the transformer oil cooling medium cavity 9.

[0032] Example 2

[0033] Building upon the basic architecture of Embodiment 1, this embodiment further refines the system's electrical control network, immersion-type modular assembly structure, and adaptive flow resistance reconfiguration mechanism. A detailed explanation of the dynamic adjustment process of the cooling flow field is provided; please refer to [link / reference needed]. Figure 3 and 5 ;

[0034] First, the electrical control network is expanded and configured. The electrical control network of the cooling explosion-proof system of the energy storage power station is configured with a 24V power supply module, multiple temperature sensors 4, control unit 5, oil pump relay 18, alarm 19, main switch 20, piezoelectric ultrasonic transducer array 23, acoustic-electric conversion damping array 21, dissipation resistor and fire linkage interface.

[0035] The 24V power module provides the DC operating voltage for the system. The power output terminal of the 24V power module is electrically connected to the power input terminals of multiple temperature sensors 4 and the power input terminal of the control unit 5. The power output terminal of the 24V power module is electrically connected to the power input terminal of the oil pump relay 18. The power output terminal of the oil pump relay 18 is electrically connected to the motor terminal of the oil pump 6.

[0036] The number of temperature sensors 4 is the same as the number of battery cells 3-1. The signal output terminals of multiple temperature sensors 4 are electrically connected to the multi-channel analog-to-digital converter input terminal of control unit 5. Control unit 5 reads the real-time temperature signals fed back by each temperature sensor 4 in parallel according to the set sampling period. Control unit 5 is equipped with a signal processing circuit, which processes the real-time temperature signal and outputs temperature characteristic parameters.

[0037] The control signal output terminal of the control unit 5 is electrically connected to the command input terminal of the oil pump relay 18. The control unit 5 sends a pulse width modulation command or a digital control command to the oil pump relay 18. The oil pump relay 18 changes the input voltage at the motor terminal of the oil pump 6 according to the received pulse width modulation command or digital control command, thereby adjusting the operating speed of the oil pump 6.

[0038] The alarm output terminal of the control unit 5 is electrically connected to the signal input terminal of the alarm 19. The control unit 5 sends an alarm trigger signal to the alarm 19. The safety control terminal of the control unit 5 is electrically connected to the control input terminal of the main switch 20. The main switch 20 is connected in series to the charging and discharging main circuit of the energy storage power station. The control unit 5 sends a disconnect command to the main switch 20 to disconnect the charging and discharging main circuit of the energy storage power station.

[0039] The high-frequency signal output terminal of the control unit 5 is electrically connected to the drive input terminal of the piezoelectric ultrasonic transducer array 23. The control unit 5 sends an ultrasonic drive AC signal to the piezoelectric ultrasonic transducer array 23. The power output terminal of the acoustic-electric conversion damping array 21 is electrically connected to the dissipation resistor. The acoustic-electric conversion damping array 21 converts the absorbed mechanical wave energy into electrical energy and outputs it to the dissipation resistor. The dissipation resistor converts the electrical energy into heat energy and consumes it.

[0040] The linkage output terminal of the control unit 5 is electrically connected to the fire linkage interface. The signal input terminal of the control unit 5 receives smoke detection signals or flame detection signals in the energy storage power station environment. When the control unit 5 receives a smoke detection signal or flame detection signal, it sends a trigger signal to the fire linkage interface and simultaneously sends a disconnect command to the main switch 20.

[0041] In addition to the electrical control logic, the immersion unit assembly structure of this system adopts a split temperature measurement and partial immersion design. The specific assembly relationship is as follows: The immersion unit assembly structure of the cooling explosion-proof system of the energy storage power station is equipped with battery cell 3-1, temperature sensor 4, thermal conductive silicone pad 10 and insulating bracket 11.

[0042] The outer surface of the battery cell 3-1 is divided into a bottom area, a side wall area and a top area. An insulating bracket 11 is set in the outer space of the battery cell 3-1. The insulating bracket 11 mechanically fixes and spatially limits the battery cell 3-1 and the temperature sensor 4. The insulating bracket 11 constructs a fluid isolation space between adjacent battery cells 3-1.

[0043] Battery cell 3-1 is installed inside the insulating support 11, and the lower part of battery cell 3-1 is immersed in transformer oil in the transformer oil cooling medium cavity 9. The level of the transformer oil is lower than the top area of ​​battery cell 3-1. The outer surface area of ​​battery cell 3-1 immersed in the transformer oil is in direct physical contact with the transformer oil. The transformer oil flows through the fluid isolation space defined by the insulating support 11, forming a forced convection circulation. The heat generated by the charging and discharging operation of battery cell 3-1 is directly conducted to the transformer oil.

[0044] The thermally conductive silicone pad 10 is attached to the side wall area of ​​the battery cell 3-1 that is not immersed in the transformer oil. The temperature sensor 4 is set on the side surface of the thermally conductive silicone pad 10 that is away from the battery cell 3-1. The temperature sensor 4 is located above the surface of the transformer oil in vertical height. The temperature sensor 4 does not have physical contact with the transformer oil. The thermally conductive silicone pad 10 fills the mechanical assembly gap between the battery cell 3-1 and the temperature sensor 4, reducing the contact thermal resistance. The thermally conductive silicone pad 10 conducts the surface temperature of the battery cell 3-1 to the temperature sensor 4.

[0045] Based on the aforementioned fluid isolation space structure, this system is configured with an adaptive flow resistance reconfiguration structure, which can automatically adjust the cooling flow distribution in each area according to the local temperature to achieve precise temperature control. The adaptive flow resistance reconfiguration structure is constructed based on the insulating support 11 and the shape memory alloy flow guide grille 22, and relies on the transformer oil flow field within the transformer oil cooling medium cavity 9 to achieve flow distribution adjustment. The insulating support 11 constructs multiple fluid isolation spaces between adjacent battery cells 3-1. The shape memory alloy flow guide grille 22 is positioned at the fluid inlet of each fluid isolation space defined by the insulating support 11. The transformer oil in the transformer oil cooling medium cavity 9... Driven by the oil pump 6, the oil flows through the shape memory alloy guide grille 22 into the fluid isolation space defined by the insulating support 11. The shape memory alloy guide grille 22 is made of temperature-sensitive shape memory alloy material. The shape memory alloy guide grille 22 is made of thin-film or wire mesh shape memory alloy material, with its thickness controlled within the range of 0.1mm to 0.5mm to shorten the thermal response time. When the transformer oil temperature reaches the critical phase change temperature, the response time of the shape memory alloy guide grille 22 is less than 2 seconds, enabling rapid flow resistance reconstruction under extreme conditions where the battery temperature rise rate reaches 5℃ / s. 2. A set critical temperature for the phase transformation from martensite to austenite is established. When the local transformer oil temperature is below the critical temperature, the shape memory alloy flow guide grid 22 is in the martensitic phase, and the grid blades of the shape memory alloy flow guide grid 22 exhibit a first geometric contraction state. When the local transformer oil temperature reaches or exceeds the critical temperature, the shape memory alloy flow guide grid 22 undergoes a phase transformation and transforms into the austenitic phase. The grid blades of the shape memory alloy flow guide grid 22 deform under heat, exhibiting a second geometric expansion state. When a local abnormal temperature rise occurs in battery cell 3-1, the transformer oil temperature around the abnormally heated battery cell 3-1 also increases accordingly. When the temperature of the transformer oil around the abnormally heated battery cell 3-1 reaches the critical phase transition temperature of the shape memory alloy flow guide grid 22, the shape memory alloy flow guide grid 22 located at the inlet of the fluid isolation space where the abnormally heated battery cell 3-1 is located undergoes a phase transition, changing from a first geometric contraction state to a second geometric expansion state. The effective fluid flow cross-sectional area of ​​the shape memory alloy flow guide grid 22 in the second geometric expansion state is greater than that in the first geometric contraction state. The volumetric flow rate distribution of the transformer oil in each fluid isolation space inside the transformer oil cooling medium cavity 9 follows the principles of pipeline fluid dynamics, flowing through the first... The local volumetric flow rate of transformer oil in each fluid isolation space is determined by the following formula:

[0046]

[0047] In the formula, For the first Local volumetric flow rate of transformer oil within a fluid isolation space; The flow coefficient corresponds to the flow rate of the fluid isolation space. The flow rate comprehensively reflects the local resistance loss and fluid contraction effect of the shape memory alloy flow guide grid 22. To be set in the The effective fluid flow cross-sectional area of ​​the shape memory alloy guide grille 22 at the entrance of the fluid isolation space; The total fluid pressure difference between the fluid inlet at the bottom and the fluid outlet at the top of the transformer oil cooling medium cavity 9; Let be the fluid density of the transformer oil. According to the above formula, the effective fluid flow cross-sectional area of ​​the shape memory alloy guide grille 22 at the inlet of the fluid isolation space where the temperature-abnormal battery cell 3-1 is located increases, leading to a decrease in the fluid resistance of the fluid isolation space corresponding to the temperature-abnormal battery cell 3-1. The shape memory alloy guide grille 22 in the area corresponding to the battery cell 3-1 where no temperature abnormality occurs maintains its first geometric contraction state, maintaining a high fluid resistance state. Under the condition of constant total fluid pressure difference or increased output pressure of oil pump 6, the transformer oil in the transformer oil cooling medium cavity 9 converges into the fluid isolation space corresponding to the temperature-abnormal battery cell 3-1 where the effective fluid flow cross-sectional area increases, increasing the convective heat transfer flow rate of the transformer oil in the area corresponding to the temperature-abnormal battery cell 3-1.

[0048] Example 3

[0049] Based on the aforementioned system structure and flow field regulation mechanism, this embodiment provides a detailed explanation of the system's graded temperature control operation logic, extreme thermal runaway intervention mechanism, explosion-proof pressure relief structure, and fire-fighting linkage function. Please refer to [link / reference needed]. Figure 2 , Figure 4 and Figure 5 ;

[0050] First, there is the stepped forced convection and delayed start-stop control under normal operation, which is executed by the control unit 5, temperature sensor 4, oil pump relay 18, alarm 19 and oil pump 6.

[0051] The control unit 5 reads the real-time temperature data collected by each temperature sensor 4 in parallel according to a sampling period of 1 second. The control unit 5 compares the real-time temperature data fed back by each temperature sensor 4 and extracts the current highest battery temperature inside the cooling and explosion-proof system of the energy storage power station.

[0052] The memory of the control unit 5 contains multi-level temperature control thresholds, including 35°C, 50°C and 65°C. The control unit 5 sends a pulse width modulation command or a digital control command to the oil pump relay 18 according to the range of the highest battery temperature to adjust the output flow of the oil pump 6.

[0053] When the maximum battery temperature is less than or equal to 35°C, the control unit 5 sends a stop command to the oil pump relay 18, and the oil pump relay 18 disconnects the power supply circuit of the oil pump 6, so the oil pump 6 is in a stopped state. When the maximum battery temperature is greater than 35°C but less than or equal to 50°C, the control unit 5 sends a low-speed operation command to the oil pump relay 18, and the oil pump relay 18 drives the oil pump 6 to run at low speed, with the output flow of the oil pump 6 being 30% of the rated maximum flow.

[0054] When the maximum battery temperature is greater than 50°C and less than or equal to 65°C, the control unit 5 sends a medium-speed operation command to the oil pump relay 18, and the oil pump relay 18 drives the oil pump 6 to run at medium speed. The output flow of the oil pump 6 is 70% of the rated maximum flow. When the maximum battery temperature is greater than 65°C, the control unit 5 sends a full-speed operation command to the oil pump relay 18, and the oil pump relay 18 drives the oil pump 6 to run at full speed. The output flow of the oil pump 6 reaches 100% of the rated maximum flow. At the same time as outputting the full-speed operation command, the control unit 5 sends an alarm trigger signal to the alarm 19.

[0055] The control unit 5 is equipped with a cooling delay shutdown logic. When the maximum battery temperature is greater than 35°C and the oil pump 6 is running, the control unit 5 continuously monitors the data change of the maximum battery temperature. When the maximum battery temperature drops to less than or equal to 32°C, the control unit 5 starts the internal timer.

[0056] Control unit 5 continuously reads the highest battery temperature during the 30-second period of the internal timer. If the highest battery temperature remains below or equal to 32°C during the 30-second period, control unit 5 sends a stop command to oil pump relay 18, and oil pump relay 18 disconnects the power supply circuit of oil pump 6. If the highest battery temperature rises above 32°C during the 30-second period, control unit 5 resets the internal timer, and oil pump 6 maintains its current operating state.

[0057] In response to the extreme temperature rise of individual battery cells that may trigger thermal runaway, the system is equipped with an ultrasonic air film stripping intervention mechanism, which is executed in concert by the control unit 5, temperature sensor 4, main switch 20, oil pump relay 18, oil pump 6 and piezoelectric ultrasonic transducer array 23.

[0058] The control unit 5 calculates the temperature characteristic parameters fed back by each temperature sensor 4 according to the set sampling period, and continuously calculates the temperature rise rate of the highest battery temperature in the cooling and explosion-proof system of the energy storage power station. The memory of the control unit 5 contains a temperature rise rate limit threshold set to 5℃ / s. When the control unit 5 detects that the temperature rise rate of the highest battery temperature is greater than 5℃ / s, the control unit 5 sends a disconnect command to the main switch 20. The main switch 20 responds to the disconnect command and cuts off the charging and discharging main circuit of the energy storage power station. The control unit 5 simultaneously sends a full-speed operation command to the oil pump relay 18, and the oil pump relay 18 drives the oil pump 6 at its rated speed. Operating at maximum flow rate accelerates the physical circulation of the transformer oil. Simultaneously, control unit 5 sends an ultrasonic drive AC signal to the piezoelectric ultrasonic transducer array 23. The piezoelectric ultrasonic transducer array 23 receives the ultrasonic drive AC signal and radiates high-frequency sound waves into the transformer oil within the transformer oil cooling medium cavity 9. The alternating sound pressure amplitude generated by the high-frequency sound waves inside the transformer oil exceeds the cavitation threshold of the transformer oil. The high-frequency sound waves propagate in the transformer oil and induce acoustic cavitation near the high-temperature region on the outer surface of the battery cell 3-1, generating cavitation bubbles. The acoustic energy density injected into the transformer oil by the piezoelectric ultrasonic transducer array 23 is determined by the following formula:

[0059]

[0060] In the formula, This refers to the acoustic energy density generated by high-frequency sound waves in transformer oil. The amplitude of the sound pressure excited by high-frequency sound waves in transformer oil; The fluid density of the transformer oil; The velocity of high-frequency sound waves in transformer oil is represented by the sound wave propagation speed. The high-density sound field energy causes cavitation bubbles to collapse asymmetrically at the interface between the outer surface of cell 3-1 and the vaporized insulating film. The collapse of cavitation bubbles generates microjets pointing towards the outer surface of cell 3-1. These microjets penetrate and strip away the vaporized insulating film on the outer surface of cell 3-1. Liquid transformer oil then passes through the stripped area of ​​the vaporized insulating film and re-contacts the outer surface of cell 3-1, restoring the direct physical heat transfer path between the transformer oil and cell 3-1.

[0061] If thermal runaway develops further and causes internal explosion, the system suppresses the explosion hazard through a multi-level explosion-proof pressure relief structure and shock wave energy dissipation mechanism. The cooling explosion-proof system of the energy storage power station includes a shell 1, a transformer oil storage area 2, a transformer oil cooling medium cavity 9, a double-layer sealing ring 12, an oil-resistant rubber pad 13, a rupture disc 14, a ceramic fiber flame-retardant layer 15, a flame-retardant foam layer 16, an explosion-proof valve 17, an acoustic-electric conversion damping array 21, and a dissipation resistor.

[0062] A double-layer sealing ring 12 and an oil-resistant rubber gasket 13 are installed at the joint of the housing 1. The double-layer sealing ring 12 and the oil-resistant rubber gasket 13 adhere to and fill the joint of the housing 1. The double-layer sealing ring 12 prevents the transformer oil inside the transformer oil cooling medium cavity 9 from leaking outwards, while the oil-resistant rubber gasket 13 resists the chemical corrosion of the transformer oil and provides mechanical cushioning. Together, they maintain the airtight state of the internal space of the housing 1. A ceramic fiber flame-retardant layer 15 is laid on the inner wall surface of the housing 1 to block the conduction of internal heat to the outside of the housing 1. A flame-retardant foam layer 16 is filled in the buffer space above the transformer oil level in the transformer oil storage area 2. The flame-retardant foam layer 16 covers the surface of the transformer oil and has a V-0 flame-retardant rating, isolating the transformer oil from the internal space. The gas has a direct contact path, suppressing secondary combustion. An explosion-proof valve 17 is installed on the side wall or top structure of the housing 1. A rupture disc 14 is installed on the top structure of the housing 1. An acoustic-electric conversion damping array 21 is fixed in the buffer space below the rupture disc 14 and is electrically connected to an external dissipation resistor. When the battery cell 3-1 experiences thermal runaway, generating gas and an explosion shock wave, the explosion shock wave propagates and acts on the acoustic-electric conversion damping array 21. The acoustic-electric conversion damping array 21 uses the piezoelectric effect to convert the mechanical energy of the explosion shock wave into electrical energy, and then transmits the electrical energy to the dissipation resistor, converting it into heat energy and consuming it. This weakens the peak pressure of the explosion shock wave reaching the inner wall of the housing 1. The electrical energy absorbed and converted by the acoustic-electric conversion damping array 21 is determined by the following formula:

[0063]

[0064] In the formula, The electrical energy output by the acoustic-to-electric conversion damping array 21; The electromechanical conversion efficiency of the acoustic-to-electric conversion damping array 21; The duration of the blast shock wave; The pressure function of the transient explosion shock wave; is a function of the vibration velocity of fluid particles subjected to shock waves; The effective wavefront area of ​​the acoustic-electric conversion damping array 21 is given by the formula above. The formula is based on a simplified model of incident acoustic energy flux density. The acoustic power per unit area is characterized by the product of fluid transient pressure and particle velocity. The incident mechanical acoustic energy is obtained by integration, and the output electrical energy of the acoustic-electric conversion damping array 21 is obtained after correction by electromechanical conversion efficiency.

[0065] As the acoustic-electric conversion damping array 21 dissipates shock wave energy, the fluid pressure inside the shell 1 increases accordingly. When the fluid pressure inside the shell 1 reaches 0.15 MPa to 0.2 MPa, the explosion-proof valve 17 opens. The explosion-proof valve 17 discharges gas unidirectionally to the outside of the shell 1, reducing the fluid pressure inside the shell 1, while simultaneously preventing external gas from entering the shell 1 in reverse from the ignition source. When the fluid pressure inside the shell 1 increases and exceeds 0.2 MPa, the rupture disc 14 ruptures, forming a large-section exhaust channel. The high-pressure gas inside the shell 1 is released to the outside through the exhaust channel, preventing the shell 1 from mechanically tearing due to overload of internal fluid pressure.

[0066] In addition to the explosion protection of the system itself, this system can also be connected to external fire protection and environmental detection equipment to form a full-link safety linkage mechanism. The cooling explosion protection system of the energy storage power station includes a shell 1, a battery cell 3-1, a control unit 5, an alarm 19, a main switch 20, an acoustic-electric conversion damping array 21, a dissipation resistor, a fire linkage interface, a smoke detector, a flame detector, and an electric air valve.

[0067] When the battery cell 3-1 experiences thermal runaway and internal explosion, the resulting shock wave propagates outward in the transformer oil. The acoustic-electric conversion damping array 21 withstands the physical impact of the shock wave. Through the deformation of the internal piezoelectric material, the acoustic-electric conversion damping array 21 converts the mechanical energy of the shock wave into electrical energy. The acoustic-electric conversion damping array 21 transmits the electrical energy to the external dissipation resistor. The dissipation resistor consumes the received electrical energy in the form of heat, attenuating the fluid kinetic energy of the shock wave and reducing the transient impact pressure on the inner wall of the casing 1.

[0068] Smoke detectors and flame detectors are installed in the energy storage power station environment. The signal output terminal of the smoke detector is electrically connected to the signal input terminal of the control unit 5, and the signal output terminal of the flame detector is electrically connected to the signal input terminal of the control unit 5. The control unit 5 receives the smoke concentration signal sent by the smoke detector and the flame characteristic signal sent by the flame detector.

[0069] The memory of control unit 5 contains a smoke concentration limit threshold. When control unit 5 detects that the smoke concentration signal reaches the smoke concentration limit threshold, or when control unit 5 receives a flame characteristic signal, control unit 5 outputs a fire-fighting linkage control command.

[0070] Control unit 5 sends a disconnect command to main switch 20, main switch 20 cuts off the charging and discharging main circuit of energy storage power station and isolates power input. Control unit 5 sends an alarm trigger signal to alarm 19, alarm 19 activates audible and visual alarm. Control unit 5 sends a linkage trigger electrical signal to fire linkage interface, fire linkage interface wakes up external fire protection system to perform environmental fire extinguishing action.

[0071] An electric air valve is installed at the normally closed vent of the housing 1. The control output terminal of the control unit 5 is electrically connected to the control input terminal of the electric air valve. While sending a linkage trigger electrical signal, the control unit 5 outputs a control signal to the electric air valve, which closes and seals the normally closed vent of the housing 1. After the air inlet and outlet of the housing 1 are sealed, the air exchange path between the internal space of the housing 1 and the external environment is cut off. The flame-retardant foam layer 16 inside the housing 1, together with the sealed oxygen-deficient environment, inhibits the spread of open flames caused by the battery cell 3-1 to the outside of the housing 1.

Claims

1. A cooling explosion-proof system for an energy storage power station, characterized in that, include: The system comprises a housing, a battery pack, a control unit, an oil pump, a heat exchange assembly, a rupture disc, an explosion-proof valve, a shape memory alloy flow guide grille, a piezoelectric ultrasonic transducer array, and an acoustic-electric conversion damping array. The housing is a sealed structure with normally closed ventilation openings. The housing internally defines a transformer oil storage area and a transformer oil cooling medium cavity, with the transformer oil storage area filled with transformer oil. The battery pack consists of multiple battery cells connected in series, and the entire battery pack is distributed within the transformer oil in the transformer oil cooling medium cavity. The transformer oil directly contacts the external housing structure of the battery cells for heat exchange. The fluid extraction end of the oil pump is connected to the bottom of the transformer oil cooling medium cavity through the oil pipeline, the fluid output end of the oil pump is connected to the fluid input end of the heat exchange component through the oil pipeline, and the fluid output end of the heat exchange component is connected to the top of the transformer oil cooling medium cavity through the oil pipeline. The shell, oil pump, heat exchange component and oil pipeline together form a forced convection circulation closed loop flow path for transformer oil. The rupture disc is disposed on the top structure of the housing, and the explosion-proof valve is disposed on the side wall or top structure of the housing; the acoustic-electric conversion damping array is arranged in the buffer space above the liquid surface of the transformer oil storage area, the shape memory alloy flow guide grid is disposed at the inlet of the cooling channel formed by each adjacent battery cell inside the transformer oil cooling medium cavity, and the piezoelectric ultrasonic transducer array is fixedly disposed on the inner wall of the transformer oil cooling medium cavity.

2. The energy storage power station cooling explosion-proof system according to claim 1, characterized in that, It also includes an insulating support, in which the battery cells are installed, and the insulating support creates multiple fluid isolation spaces between adjacent battery cells; the shape memory alloy flow guide grid is made of a temperature-sensitive shape memory alloy material, and the shape memory alloy flow guide grid has a set phase transformation critical temperature for the transformation from martensite to austenite. When the temperature of the transformer oil around the battery cell with abnormal temperature reaches the phase transition critical temperature, the shape memory alloy guide grid at the inlet of the fluid isolation space where the battery cell with abnormal temperature is located undergoes a phase transition, changing from the first geometric contraction state to the second geometric expansion state. The local volumetric flow rate of transformer oil flowing through the corresponding fluid isolation space is determined by the following formula: In the formula, For the first Local volumetric flow rate of transformer oil within a fluid isolation space; The flow coefficient corresponds to the flow rate of the fluid isolation space. The flow rate comprehensively reflects the local resistance loss and fluid contraction effect of the shape memory alloy flow guide grid. To be set in the The effective fluid flow cross-sectional area of ​​the shape memory alloy guide grille at the inlet of the fluid isolation space; The total fluid pressure difference between the fluid inlet at the bottom and the fluid outlet at the top of the transformer oil cooling medium cavity; This refers to the fluid density of the transformer oil.

3. The energy storage power station cooling explosion-proof system according to claim 1, characterized in that, It also includes multiple temperature sensors and an oil pump relay, with the signal output terminals of the multiple temperature sensors electrically connected to the multi-channel analog-to-digital converter input terminal of the control unit; The control unit is used to calculate the temperature characteristic parameters fed back by each of the temperature sensors according to the set sampling period, and to continuously calculate the rate of change of the highest battery temperature in the system. When the control unit detects that the rate of temperature change of the highest battery temperature is greater than the set limit threshold of 5℃ / s, the control unit sends an ultrasonic drive AC signal to the piezoelectric ultrasonic transducer array. The piezoelectric ultrasonic transducer array radiates high-frequency sound waves into the transformer oil, and the sound energy density injected into the transformer oil by the piezoelectric ultrasonic transducer array is determined by the following formula: In the formula, This refers to the acoustic energy density generated by high-frequency sound waves in transformer oil. The amplitude of the sound pressure excited by high-frequency sound waves in transformer oil; The fluid density of the transformer oil; This represents the propagation speed of high-frequency sound waves in transformer oil.

4. The energy storage power station cooling explosion-proof system according to claim 3, characterized in that, The alternating sound pressure amplitude generated by the high-frequency sound wave inside the transformer oil is greater than the cavitation threshold of the transformer oil. The high-frequency sound wave induces acoustic cavitation effect and generates cavitation bubbles in the high-temperature region on the outer surface of the battery cell. The cavitation bubbles undergo asymmetric collapse at the interface between the outer surface of the battery cell and the vaporized insulating gas film, generating microjets pointing towards the outer surface of the battery cell. The microjets penetrate and peel off the vaporized insulating gas film on the outer surface of the battery cell, allowing the liquid transformer oil to pass through the peeled area of ​​the vaporized insulating gas film and re-contact the outer surface of the battery cell.

5. The energy storage power station cooling explosion-proof system according to claim 1, characterized in that, It also includes a dissipation resistor, and the acoustic-electric conversion damping array is electrically connected to the external dissipation resistor; When the battery cell experiences thermal runaway, generating gas and an explosion shock wave, the explosion shock wave propagates and acts on the acoustic-electric conversion damping array. The acoustic-electric conversion damping array utilizes the piezoelectric effect to convert the mechanical energy of the explosion shock wave into electrical energy. The acoustic-electric conversion damping array transmits electrical energy to the dissipation resistor, converts it into heat energy, and consumes it, thereby weakening the peak pressure of the explosion shock wave reaching the inner wall of the shell.

6. The energy storage power station cooling explosion-proof system according to claim 1, characterized in that, It also includes thermally conductive silicone pads and temperature sensors; The lower part of the battery cell is immersed in the transformer oil in the transformer oil cooling medium cavity, and the liquid level of the transformer oil is lower than the top area of ​​the battery cell. The thermally conductive silicone pad is attached to the side wall area of ​​the battery cell that is not immersed in the transformer oil. The temperature sensor is disposed on the surface of the thermally conductive silicone pad that is away from the battery cell. The temperature sensor is located above the surface of the transformer oil in vertical height and does not have physical contact with the transformer oil.

7. The energy storage power station cooling explosion-proof system according to claim 1, characterized in that, It also includes an oil pump relay and an alarm, and the memory of the control unit contains multiple levels of temperature control thresholds; The control unit extracts the current highest battery temperature inside the cooling and explosion-proof system of the energy storage power station, and sends a pulse width modulation command or digital control command to the oil pump relay according to the numerical range of the highest battery temperature, thereby changing the input voltage at the motor end of the oil pump and adjusting the operating speed of the oil pump. When the maximum battery temperature exceeds 65°C, the control unit sends a full-speed operation command to the oil pump relay and simultaneously sends an alarm trigger signal to the alarm.

8. The energy storage power station cooling explosion-proof system according to claim 1, characterized in that, The system also includes a double-layer sealing ring, an oil-resistant rubber gasket, a ceramic fiber flame-retardant layer, and a flame-retardant foam layer; The double-layer sealing ring is attached to and fills the splicing gap of the shell with the oil-resistant rubber gasket, and the ceramic fiber flame-retardant layer is laid on the inner wall surface of the shell; The flame-retardant foam layer fills the buffer space above the transformer oil surface in the transformer oil storage area. The flame-retardant foam layer covers the transformer oil surface and has a V-0 flame-retardant rating, thus blocking the direct contact path between the transformer oil and the internal gas.

9. The energy storage power station cooling explosion-proof system according to claim 8, characterized in that, When the fluid pressure inside the shell reaches 0.15MPa to 0.2MPa, the explosion-proof valve opens, releasing gas unidirectionally to the outside of the shell and preventing external gas from entering the shell in reverse from the ignition source. When the fluid pressure inside the shell increases and exceeds 0.2 MPa, the rupture disc breaks, forming a large-section exhaust channel to release the high-pressure gas inside the shell to the outside.

10. The energy storage power station cooling explosion-proof system according to claim 1, characterized in that, The system also includes a main switch, a fire alarm linkage interface, smoke detectors, flame detectors, and electric dampers; The electric air valve is located at the normally closed ventilation opening of the housing. When the control unit detects that the smoke concentration signal sent by the smoke detector reaches the smoke concentration limit threshold, or receives the flame characteristic signal sent by the flame detector, the control unit sends a disconnect command to the main switch to cut off the charging and discharging main circuit, sends a linkage trigger electrical signal to the fire linkage interface, and outputs a control signal to the electric air valve to close the electric air valve and seal the normally closed ventilation opening of the housing.

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