High-voltage direct-coupled lithium iron phosphate battery system for mine emergency energy storage power supply and operation method

Abstract

The application discloses a lithium iron phosphate battery system for high-voltage direct-hanging mine emergency energy storage power supply and an operation method thereof. The battery system is composed of multiple energy storage units corresponding to high-voltage battery clusters and link power modules, and three-phase star connection is formed through cascading of the link power modules, so that the battery system can be directly connected to a high-voltage alternating current power grid without a step-up transformer. The battery cell adopts a lithium iron phosphate system, the battery module, the battery pack and the battery cluster adopt a multi-level grouping structure, and a liquid cooling system, a ventilation system, a perfluorohexanone and water spraying fire extinguishing system and a three-level architecture BMS are configured to realize SOC / SOH monitoring, fault diagnosis and hierarchical protection. The application is suitable for mine emergency high-voltage direct-hanging energy storage equipment.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage and mine power supply and distribution safety technology, specifically to a high-voltage direct-connected lithium iron phosphate battery system for mine emergency energy storage and its operation method. Background Technology

[0002] Coal mines have high requirements for power supply continuity and security, especially during external power grid failures or maintenance, requiring reliable backup and emergency power supply capabilities. Existing energy storage systems typically require step-up transformers and low-voltage combiner, step-up, and grid-connection devices on the high-voltage grid side, resulting in complex system configurations, increased footprint, and higher losses, making them unsuitable for installation and application in space-constrained locations such as underground mines and mine entrances.

[0003] On the other hand, with the widespread application of lithium iron phosphate batteries in electrochemical energy storage, how to ensure high-voltage direct grid connection while achieving consistent control, thermal management, and safety management across multiple levels of the battery cluster, from individual cells, modules, and packs to the entire cluster, remains a challenge in engineering practice. This is especially true in mining environments, where a balance needs to be struck between environmental conditions such as temperature, humidity, and altitude, as well as cell cycle life and safety performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of complex high-voltage grid connection, low system efficiency, and insufficient thermal and safety management of energy storage batteries in coal mine scenarios in existing technologies. It proposes a high-voltage direct-connected lithium iron phosphate battery system and operation method for mine emergency energy storage power supply. Through chain-cascaded direct-connection topology, refined battery hierarchical grouping structure, and supporting liquid cooling, ventilation and fire protection systems, the energy storage system achieves high-voltage direct connection, safety and reliability, and ease of maintenance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high-voltage direct-connected lithium iron phosphate battery system for mine emergency energy storage includes multiple energy storage units and a high-voltage AC grid-connected unit. Each energy storage unit includes an H-bridge DC / AC power unit and an independent battery cluster, which is composed of lithium iron phosphate cells arranged in a multi-level group structure. Multiple H-bridge DC / AC power units are cascaded to form a three-phase star connection and then connected to the high-voltage AC grid-connected unit, allowing the system to be directly connected to the high-voltage AC power grid. The system is equipped with a liquid cooling system, a ventilation system, a fire protection system, and a three-level BMS architecture. The fire protection system includes a perfluorohexanone fire extinguishing device and a water sprinkler system. The BMS includes a battery array management unit, a battery cluster management unit, and a battery acquisition unit.

[0007] Furthermore, the battery cluster adopts a 2P340S grouping method, consisting of five 56S2P battery packs and one 60S2P battery pack connected in series, with a nominal voltage of 1088V, a nominal capacity of 200Ah, a nominal charge of 217.6kWh, and an operating voltage range of 952V~1241V.

[0008] Furthermore, both the 56S2P and 60S2P battery packs adopt a 2P56S and 2P60S grouping method. Each battery pack consists of four 2P14S battery modules or four 2P15S battery modules connected in series, with a nominal capacity of 200Ah. The nominal voltage of the 56S2P battery pack is 179.2V, and the nominal voltage of the 60S2P battery pack is 192V.

[0009] Furthermore, the battery module adopts a 2P14S or 2P15S assembly method, and each battery module is composed of lithium iron phosphate cells connected in parallel and series, with a nominal capacity of 200Ah. The nominal voltage of the 2P14S module is 44.8V, and the nominal voltage of the 2P15S module is 48V.

[0010] Furthermore, the liquid cooling system is an integrated liquid cooling unit, equipped with supply and return liquid pipelines, which are connected to the heat exchange components of each battery box or battery cluster to achieve consistent control of battery operating temperature.

[0011] Furthermore, the ventilation system includes a smoke exhaust fan and motorized louvers, and the ventilation system is electrically connected to an alarm controller; the alarm controller activates the smoke exhaust fan and motorized louvers in response to a first-level alarm, and deactivates the smoke exhaust fan and motorized louvers in response to a second-level alarm.

[0012] Furthermore, the fire protection system includes a composite detector, an internal composite detector, a fire control cabinet, a perfluorohexanone fire extinguishing device, and a water sprinkler system; the fire control cabinet is equipped with three-level control logic: when a level one alarm is triggered, an audible and visual alarm is activated and emergency ventilation is started; when a level two alarm is triggered, the battery management system is activated to disconnect the power supply, shut down the air conditioning and emergency ventilation, and start the perfluorohexanone circulating point spray or the entire cabin total flooding spray; when a level three alarm is triggered, the water sprinkler system is activated for continuous cooling and fire extinguishing after manual confirmation.

[0013] Furthermore, the three-level architecture BMS includes a battery array management unit located in the combiner control cabinet, a battery cluster management unit that communicates with the battery array management unit, and a battery acquisition unit that communicates with the battery cluster management unit. The battery acquisition unit acquires the individual cell voltage and temperature, the battery cluster management unit acquires the total voltage and current of the battery cluster and estimates the battery cluster SOC / SOH, and the battery array management unit interacts with the PCS, EMS, and cloud platform.

[0014] Furthermore, the system adopts a container-type cabin structure, which includes a battery room, a junction room, and a power distribution room. The battery room is equipped with battery racks, and the battery racks hold battery boxes. The junction room is equipped with a high-voltage box and a junction control cabinet. The power distribution room is equipped with an air-cooled air conditioner, a ventilation device, a dehumidifier, and a liquid-cooled unit. The battery room and the junction room are connected by electrical lines, and the power distribution room supplies power to each electrical device.

[0015] This invention also provides an operation method for a high-voltage direct-connected lithium iron phosphate battery system for mine emergency energy storage, comprising: controlling the external ambient humidity of the battery system to be 10%~90%RH; maintaining the state of charge (SOC) of the battery system at no less than 10% during operation; maintaining the SOC at no less than 60% and storing it in a warehouse at 5℃~45℃ during short-term non-use; conducting charge-discharge tests and battery status monitoring at least once a month, including monitoring total voltage, individual cell voltage, temperature, voltage difference, temperature difference, insulation resistance, and SOC; handling the battery pack with care during loading and unloading, preventing dropping, rolling, and impact; not inverting or laying it flat during storage; keeping the battery system away from flammable and explosive materials and high-temperature environments during operation; stopping operation when the battery system is short-circuited, overcharged, or under high-temperature alarm conditions; and prohibiting unauthorized disassembly of the battery system.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects:

[0017] (1) The high-voltage chain direct connection topology is adopted. A three-phase star connection is formed by cascading multiple H-bridge power units. It can be directly connected to the 10kV high-voltage AC power grid without the need to set up a large-capacity step-up transformer, which reduces the complexity of the system structure and engineering investment, and improves the system efficiency.

[0018] (2) In terms of battery pack structure, starting from a 100Ah single lithium iron phosphate cell, a multi-level packing method is adopted, from 2P14S / 2P15S battery modules, 2P56S / 2P60S battery packs to 2P340S high-voltage battery clusters. This method takes into account modular maintenance and matching of system voltage and current levels, which is conducive to improving system reliability and balance.

[0019] (3) The cell SOC usage window is 10%~100%. Under 0.2C charge and discharge and normal temperature conditions, the number of cycles is not less than 6500 and the capacity retention rate is not less than 80%. Combined with the cooling of the battery box by the liquid cooling integrated machine and the suitable ambient temperature range (-20℃~60℃), it can achieve a long service life and good performance stability in coal mine scenarios.

[0020] (4) By setting up a ventilation system, a perfluorohexanone circulating point spray + total flooding system and a water spray system, and combining multi-level control logic such as first-level early warning, second-level alarm and third-level alarm, the system can achieve progressive protection from early thermal runaway signal detection to gas extinguishing and water spray cooling, thereby improving the inherent safety level of the system.

[0021] (5) A three-level BMS architecture is adopted to implement multi-level monitoring and control of individual cells, battery clusters and battery stacks. Through SOC / SOH estimation and data interaction with PCS / EMS / cloud platform, intelligent operation and remote maintenance of coal mine high-voltage direct-connected energy storage system are realized. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a single-cell lithium iron phosphate battery.

[0023] Figure 2 This is a schematic diagram of the battery module structure.

[0024] Figure 3 This is a schematic diagram of the battery pack structure.

[0025] Figure 4 This is a schematic diagram of the overall structure of the present invention.

[0026] Figure 5 This is a schematic diagram of the fire protection logic.

[0027] The attached diagram is labeled as follows: first pole assembly 1, liquid injection port assembly 2, pressure relief safety valve 3, second pole assembly 4, manifold 5, battery compartment side door 6, ventilation device 7, high-voltage box 8, battery rack 9, lifting shaft 10, dehumidifier 11, liquid cooling unit 12, power distribution room 41, air-cooled air conditioner 31, fire room 13, and battery compartment 21. Detailed Implementation

[0028] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0029] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "up," "down," and similar expressions used herein are for illustrative purposes only and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0031] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0032] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0033] The present invention discloses a high-voltage direct-connected lithium iron phosphate battery system for mine emergency energy storage, comprising multiple energy storage units and a high-voltage AC grid-connected unit electrically connected to the energy storage units; wherein, each energy storage unit includes a set of H-bridge DC / AC power units and a set of independent battery clusters corresponding to the DC / AC power units; the multiple DC / AC power units are cascaded and connected in a three-phase star configuration to the high-voltage AC grid-connected unit, enabling the battery system to be directly connected to the high-voltage AC grid without the need for a step-up transformer.

[0034] This invention employs a hierarchical battery structure consisting of 2P14S / 2P15S battery modules, 2P56S / 2P60S battery packs, and 2P340S high-voltage battery clusters made of lithium iron phosphate cells. A liquid cooling system enables battery box-level thermal management, while a multi-stage fire suppression system combining ventilation and perfluorohexanone with water spraying provides early detection and suppression of thermal runaway. A three-tiered battery management system (BMS) is used to monitor and manage cell voltage, temperature, and battery cluster SOC / SOH.

[0035] Preferably, the system is provided with 10 high-voltage battery clusters, each of which is electrically connected to a link power module.

[0036] Preferably, the high-voltage battery cluster is assembled in a 2P340S configuration, with a nominal voltage of 1088V, a nominal capacity of 200Ah, a nominal charge of 217.6kWh, a system operating voltage range of 952V~1241V, and a rated charging current and a rated discharging current of 200A.

[0037] Preferably, the high-voltage battery cluster is composed of five 56S2P battery boxes and one 60S2P battery box connected in series; both the 56S2P battery box and the 60S2P battery box are composed of multiple battery modules, and the battery modules are arranged in a 2P14S or 2P15S configuration. The nominal capacity of a single battery module is 200Ah, and the nominal voltages are 44.8V and 48V, respectively, corresponding to nominal energies of 8.96kWh and 9.6kWh, respectively.

[0038] Preferably, the battery module uses lithium iron phosphate cells, each with a nominal capacity of 100Ah, a nominal voltage of 3.2V, an operating voltage range of 2.8V~3.6V, and a single cell AC internal resistance of no more than 0.5mΩ (1kHz, 50% SOC, initial state).

[0039] Preferably, the nominal voltages of the 56S2P battery box and the 60S2P battery box are 179.2V and 192V, respectively, corresponding to minimum operating voltages of 156.8V and 168V, and maximum operating voltages of 204.4V and 219V, respectively. The nominal capacity is 200Ah, and the nominal energy is 35.84kWh and 38.4kWh, respectively. The external dimensions of the battery box are approximately 1110mm × 770mm × 254mm, and thermal management is achieved through liquid cooling.

[0040] Preferably, it is suitable for installation and operation under the following conditions: ambient temperature -20℃~60℃, storage temperature 5℃~45℃, relative humidity 0~95% without condensation, altitude 0~2000m, and atmospheric pressure 79kPa~106kPa. Furthermore, when the battery system is working, the external ambient humidity is preferably controlled at 10%~90%RH.

[0041] Preferably, the system also includes a liquid cooling system, which is an integrated liquid cooling unit. Each system is equipped with a 60kW liquid cooling unit, and the liquid cooling unit is connected to the heat exchange components of each battery box or battery cluster through supply and return liquid pipelines to achieve consistent control of battery operating temperature.

[0042] Preferably, the system also includes a ventilation system, which includes two sets of smoke exhaust fans and two sets of motorized louvers installed in the system; the ventilation system is electrically connected to an alarm controller, which activates the smoke exhaust fans and motorized louvers in response to a first-level alarm and deactivates them in response to a second-level alarm.

[0043] Preferably, the system also includes a fire suppression system, which comprises a perfluorohexanone fire extinguishing device, a composite detector, an internal composite detector, and a fire control cabinet. The fire control cabinet is equipped with three-level control logic: upon a level one alarm, it triggers an audible and visual alarm and activates emergency ventilation; upon a level two alarm, it triggers the battery management system to disconnect the power supply, shut down the air conditioning and emergency ventilation, and activates perfluorohexanone circulating point spray or full-cabin flooding spray; upon a level three alarm, after manual confirmation, it activates water spray to continuously cool and extinguish the fire in the system.

[0044] Preferably, the system also includes a battery management system (BMS). The BMS adopts a three-level architecture and includes at least a battery array management unit (BAU) located in the combiner control cabinet, a battery cluster management unit (BCU) communicating with the BAU, and a battery acquisition unit (BMU). The BMS is used to collect information such as individual cell voltage, individual cell temperature, total voltage and total current of the battery cluster, estimate the SOC / SOH of the battery cluster and battery stack, and realize the detection and protection against overvoltage, undervoltage, overtemperature, undertemperature, overcurrent and insulation faults based on thresholds such as voltage, current, temperature and SOC / SOH.

[0045] Example 1: 6.5MWh high-voltage direct-connected mine emergency energy storage power system.

[0046] The energy storage system in this embodiment includes three battery compartments, a 10kV high-voltage switchgear, a starter cabinet, a distribution cabinet, and an energy management system (EMS). The battery compartments are non-walk-in containerized structures, each a 20-foot non-standard container. Each compartment is equipped with 10 high-voltage battery clusters, each corresponding to a single power module link. The 10 power modules linking to the switchgear are connected in series and then connected to the 10kV high-voltage switchgear, with grid-connected / off-grid control achieved via the starter cabinet.

[0047] Regarding individual battery cells, such as Figure 1 As shown, the top cover of the battery cell is equipped with a first terminal assembly 1, a liquid injection port assembly 2, a pressure relief safety valve 3, and a second terminal assembly 4. The battery cell uses lithium iron phosphate cells, with a nominal capacity of 100Ah per cell, a cell energy of approximately 320Wh, an operating voltage range of 2.8V~3.6V, a nominal voltage of 3.2V, and an AC internal resistance AC-IR (1kHz) of no more than 0.5mΩ (New Cell, 50% SOC, BOL). The recommended SOC operating window is 10%~100%; the cell should have at least 6500 cycles under 0.2C charge / discharge at room temperature, with a capacity retention of no less than 80%. The cell charging temperature range is 0℃~60℃, and the discharging temperature range is -20℃~60℃.

[0048] Regarding battery modules, such as Figure 2 As shown, the battery modules are assembled in a 2P14S or 2P15S configuration, with a nominal module capacity of 200Ah, corresponding to a nominal module voltage of 44.8V / 48V, and a nominal module energy of 8.96kWh / 9.6kWh. The module's AC internal resistance (AC-IR) (1kHz) is no greater than 0.5mΩ. A SOC operating window of 5%~100% is also recommended, with a charge / discharge temperature range of 0℃~60℃ (charging) and -20℃~60℃ (discharging), suitable for the temperature fluctuations of mining environments described in this invention.

[0049] Regarding the battery pack, such as Figure 3 As shown, the battery pack is assembled in either a 2P56S or 2P60S configuration, corresponding to four 2P14S modules or four 2P15S modules connected in series, respectively. The nominal voltages of the 2P56S and 2P60S battery packs are 179.2V and 192V, respectively; the minimum operating voltages are 156.8V and 168V, respectively; the maximum operating voltages are 204.4V and 219V, respectively; the nominal capacity is 200Ah; and the nominal energy is 35.84kWh and 38.4kWh, respectively. The battery pack dimensions are approximately 1110mm × 770mm × 254mm, and liquid cooling is used for thermal management of the internal battery cells.

[0050] Specifically, such as Figure 4 As shown, the high-voltage direct-connected lithium iron phosphate battery system for mine emergency energy storage power supply of the present invention uses battery compartment 21 as the core functional compartment, with battery rack 9 installed inside as the main energy storage body. The liquid cooling unit 12 realizes the thermal management of the battery cells and is electrically connected to the combiner room 5 for DC collection, and then outputs high voltage to the outside through the high-voltage box 8. The power distribution room 41 serves as the low-voltage power distribution and control center, supplying power to the air-cooled air conditioner 31, ventilation device 7, dehumidifier 11, liquid cooling unit 12 and fire room 13, and collecting monitoring signals and alarms to issue control commands. The fire room 13 is responsible for fire detection and alarm. In the event of thermal runaway, it can link the power distribution room 41 and the high-voltage box 8 to cut off the high voltage and start the fire extinguishing and smoke exhaust strategy. The air-cooled air conditioner 31, ventilation device 7 and dehumidifier 11 work together to control the temperature and humidity of battery compartment 21. The side door 6 of battery compartment improves operational safety through interlocking signals, and the lifting shaft 10 is used for the hoisting, transportation and positioning of the entire cabinet.

[0051] Regarding the battery clusters, each high-voltage battery cluster adopts a 2P340S assembly method, consisting of five 56S2P battery packs and one 60S2P battery pack connected in series. The nominal voltage is 1088V, the nominal capacity is 200Ah, and the nominal charge is 217.6kWh. The system operating voltage range is 952V~1241V, and both the rated charging current and rated discharging current are 200A. Each system contains 10 high-voltage battery clusters, resulting in a single system nominal charge of 2.176MWh and a total nominal charge of approximately 6.5MWh for the three systems.

[0052] Regarding environmental and usage conditions, the battery system of this embodiment is suitable for environments with an ambient temperature of -20℃ to 60℃ and a storage temperature of 5℃ to 45℃. The system can achieve full-performance operation within a temperature range of 0℃ to 60℃, and can start up and run continuously at -20℃. The relative humidity range is 0% to 95% with no condensation, and it is preferable to control the external ambient humidity at 10% to 90%RH during battery system operation; it is suitable for installation scenarios with an altitude of 0 to 2000m and an atmospheric pressure of 79kPa to 106kPa.

[0053] In terms of safety protection, the system is equipped with a ventilation system and a fire protection system. The ventilation system includes two sets of smoke exhaust fans and two sets of motorized louvers, along with a fan control cabinet. In the event of a Level 1 alarm, the alarm controller will activate the smoke exhaust fans and motorized louvers for emergency ventilation. In the event of a Level 2 alarm, the smoke exhaust fans and motorized louvers will be deactivated to prepare for the perfluorohexanone injection operation.

[0054] The fire protection system includes an internal composite detector, a composite detector, a perfluorohexanone fire extinguishing system, a water sprinkler system, and a fire control cabinet. The internal composite detector is used to detect local temperature and carbon monoxide concentration changes within the battery pack, while the composite detector is used to detect fire signals throughout the entire battery system.

[0055] The fire control cabinet adopts a three-level control logic:

[0056] Level 1 Warning: ① When the internal dual-in-one detector reaches the warning temperature or the CO concentration reaches the preset Level 1 warning value, the alarm unit sounds an alarm, the display and control unit highlights the relevant parameters exceeding the standard, and the controller activates the audible and visual alarm, smoke exhaust fan, and motorized louvers to alert staff to the situation in the protected area, while simultaneously transmitting the warning signal (dry contact or RS485 passive reading). ② If the five-in-one composite detector triggers a Level 1 warning, it will activate the audible and visual alarm, smoke exhaust fan, and motorized louvers to alert staff to the situation in the protected area, while simultaneously transmitting the warning signal (dry contact or RS485 passive reading).

[0057] Level 2 Alarm: ① If the internal dual-function detector uploads a Level 2 thermal runaway alarm signal, the alarm unit will sound, the controller will trigger the BMS to disconnect power, shut down the air conditioning, turn off the smoke exhaust fan and motorized louvers, activate the audible and visual alarm, open the puncture valve outside the battery pack and the cluster-level solenoid valve of the battery cluster according to the alarm area, and the fire extinguishing device will perform a cyclic spraying action (spraying perfluorohexanone) on the thermal runaway battery pack. At the same time, the venting indicator light will be activated to promptly notify relevant personnel. ② If the five-in-one composite detector uploads a Level 2 thermal runaway alarm signal, the controller will trigger the BMS to disconnect power, shut down the air conditioning, turn off the smoke exhaust fan and motorized louvers, activate the audible and visual alarm, open the solenoid valve, activate the fire extinguishing device for total flooding spraying of the entire compartment, and simultaneously activate the venting indicator light to promptly notify relevant personnel.

[0058] Level 3 Alarm: If the fire is not controlled and spreads after the perfluorohexanone fire extinguishing action is completed, the composite detector will upload a Level 3 fire alarm signal. The fire situation will be manually confirmed, and water sprinklers will be manually activated for continuous cooling and fire extinguishing. Relevant personnel will be notified immediately. See details for the specific logic. Figure 5 .

[0059] In terms of battery management, the BMS adopts a three-level architecture. The Battery Acquisition Unit (BMU) is located at the module level, collecting information such as individual cell voltage and temperature, and uploading the data to the Battery Cluster Management Unit (BCU). The BCU is located at the battery cluster level, collecting the total voltage, total current, and insulation status of the battery cluster, and summarizing and processing individual cell data to achieve SOC / SOH estimation and charge / discharge allowable power calculation at the battery cluster level. The Battery Array Management Unit (BAU) is located in the combiner control cabinet and is the control core of the system. It interacts with the PCS, EMS, and cloud platform, records historical operating data, and outputs fault diagnosis and protection strategies. Through the coordinated operation of the BMU, BCU, and BAU, graded alarms and isolation measures can be implemented for overvoltage, undervoltage, overtemperature, low-temperature, overcurrent, and insulation faults.

[0060] Example 2: Operation method and maintenance constraints.

[0061] This embodiment provides an operation and maintenance method compatible with the above-described energy storage system:

[0062] (1) The external humidity requirement for the battery system is 10%~90%RH. During the operation and maintenance of the system, it should be avoided to be in extreme humid and hot or condensing conditions for a long time.

[0063] (2) During operation, maintain the SOC (State of Charge) of the battery system at no less than 10% to avoid frequent triggering of overcharge and discharge protection;

[0064] (3) When not in use for a short period of time, maintain the SOC at no less than 60% and store in a dry, clean and well-ventilated warehouse at 5℃~45℃;

[0065] (4) Charge and discharge tests and battery status monitoring shall be conducted at least once a month. The monitoring content shall include at least total voltage, individual cell voltage, temperature, voltage difference, temperature difference, insulation resistance and SOC. If any abnormality is found, maintenance personnel shall be notified in time to troubleshoot the fault.

[0066] (5) During the loading and unloading of the battery pack, it is required to handle it with care and prevent it from being dropped, rolled or impacted; it must not be inverted or laid flat during storage, and the battery pack must not be exposed to the sun, rain or water for a long time.

[0067] (6) During the operation of the energy storage system, daily maintenance and inspection must be carried out in strict accordance with the usage requirements to ensure that the battery system is kept away from flammable and explosive materials and high-temperature environments during operation or storage.

[0068] (7) It is strictly forbidden to force operation when the battery system is short-circuited, overcharged or under high temperature alarm state. Users are strictly prohibited from disassembling the battery system without permission.

[0069] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the embodiments and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0070] Those skilled in the art, guided by the teachings of this invention, may make substitutions or modifications without departing from the scope of protection of the claims of this invention, all of which fall within the protection scope of this invention. The scope of protection of this invention shall be determined by the appended claims.

Claims

1. A lithium iron phosphate battery system for a high-voltage direct-connected mine emergency energy storage power supply, characterized in that, Through a chain-cascaded direct-connection topology, a refined battery hierarchical grouping structure, and supporting liquid cooling, ventilation, and fire protection systems, the energy storage system achieves high-voltage direct connection, safety, reliability, and ease of maintenance. It includes multiple energy storage units and a high-voltage AC grid-connected unit. Each energy storage unit includes an H-bridge DC / AC power unit and an independent battery cluster corresponding to that H-bridge DC / AC power unit. The battery cluster is formed by assembling lithium iron phosphate cells into battery modules and battery packs in a step-by-step manner. Multiple H-bridge DC / AC power units are cascaded to form a three-phase star connection and then connected to the high-voltage AC grid-connected unit, allowing the system to directly connect to the high-voltage AC power grid. The system is equipped with a liquid cooling system, a ventilation system, a fire protection system, and a three-level BMS architecture. The BMS includes a Battery Array Management Unit (BAU), a Battery Cluster Management Unit (BCU), and a Battery Acquisition Unit (BMU). The ventilation system includes a smoke exhaust fan and motorized louvers, and is electrically connected to an alarm controller; the alarm controller activates the smoke exhaust fan and motorized louvers in response to a level one alarm, and deactivates the smoke exhaust fan and motorized louvers in response to a level two alarm. The fire protection system includes a composite detector, an internal composite detector, a fire control cabinet, a perfluorohexanone fire extinguishing device, and a water sprinkler system. The fire control cabinet is equipped with three-level control logic: a level one alarm triggers an audible and visual alarm and activates emergency ventilation, but does not activate the fire extinguishing device; a level two alarm triggers the BMS to disconnect the power supply, shut down the air conditioning and emergency ventilation, and activates perfluorohexanone circulating point spray or full-cabin total flooding spray; if the perfluorohexanone fire extinguishing fails to control the fire and a level three alarm occurs, the water sprinkler system is activated for continuous cooling and fire extinguishing after manual confirmation. The battery cluster adopts a 2P340S grouping method, consisting of five 56S2P battery packs and one 60S2P battery pack connected in series. The nominal voltage is 1088V, the nominal capacity is 200Ah, the nominal energy is 217.6kWh, and the operating voltage range is 952V~1241V. Both the 56S2P and 60S2P battery packs adopt a 2P56S and 2P60S grouping method. Each battery pack consists of four 2P14S battery modules or four 2P15S battery modules connected in series, with a nominal capacity of 200Ah. The nominal voltage of the 56S2P battery pack is 179.2V, and the nominal voltage of the 60S2P battery pack is 192V.

2. The lithium iron phosphate battery system for a high-voltage direct-connected mine emergency energy storage power supply according to claim 1, characterized in that, The battery modules are assembled in a 2P14S or 2P15S configuration. Each battery module consists of lithium iron phosphate cells connected in parallel and series, with a nominal capacity of 200Ah. The nominal voltage of the 2P14S module is 44.8V, and the nominal voltage of the 2P15S module is 48V.

3. The lithium iron phosphate battery system for a high-voltage direct-connected mine emergency energy storage power supply according to claim 1, characterized in that, The liquid cooling system is an integrated liquid cooling unit, with each battery system equipped with a 60kW liquid cooling unit. The liquid cooling unit has a liquid supply pipeline and a liquid return pipeline, which are connected to the heat exchange components of each battery box or battery cluster to achieve consistent control of the battery operating temperature.

4. The lithium iron phosphate battery system for a high-voltage direct-connected mine emergency energy storage power supply according to claim 1, characterized in that, The three-tier BMS architecture includes a Battery Array Management Unit (BAU) located in the combiner control cabinet, a Battery Cluster Management Unit (BCU) communicatively connected to the BAU, and a Battery Acquisition Unit (BMU) communicatively connected to the BCU. The BMU is located at the battery module level and acquires the individual cell voltage and temperature. The BCU acquires the total voltage, total current, and insulation status of the battery cluster, estimates the SOC / SOH of the battery cluster, and calculates the allowable charge and discharge power. The BAU interacts with the PCS, EMS, and cloud platform to output fault diagnosis and protection strategies.

5. A high-voltage direct-connected lithium iron phosphate battery system for mine emergency energy storage power supply according to claim 1, characterized in that, The system adopts a containerized cabin structure, which includes a battery room, a junction room, and a power distribution room. The battery room is equipped with battery racks, and the battery racks hold battery boxes. The junction room is equipped with a high-voltage box and a junction control cabinet. The power distribution room is equipped with an air-cooled air conditioner, a ventilation device, a dehumidifier, and a liquid-cooled unit. The battery room and the junction room are connected by electrical lines, and the power distribution room supplies power to all electrical equipment.

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