A distributed energy storage system based on span battery and a control method thereof

Abstract

This invention discloses a distributed energy storage system based on SPAN batteries, characterized by comprising: at least one photovoltaic support frame, with photovoltaic modules mounted on the upper part of the photovoltaic support frame; an integrated SPAN energy storage module mounted on the photovoltaic support frame near the back side of the photovoltaic modules; the integrated SPAN energy storage module comprising at least one battery cell using polyacrylonitrile sulfate (PAS) as the positive electrode active material; connected to a DC converter via a DC combiner box or DC bus; the DC converter connected to an energy storage inverter or a grid-connected inverter, and connected to the power grid or load via the energy storage inverter or grid-connected inverter; and an EMS management unit or energy management unit performing energy dispatching of the system based on photovoltaic output, grid status, load demand, and energy storage module status. This invention also discloses its control method. Compared with existing containerized energy storage systems, this invention has a smaller footprint, and individual energy storage modules can be independently replaced.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, specifically to a distributed energy storage system based on SPAN batteries and its control method. Background Technology

[0002] Existing photovoltaic energy storage systems typically house energy storage batteries in independent energy storage containers, cabinets, or battery compartments. This approach requires additional land, and long DC or AC cables are needed between the photovoltaic array and the energy storage system, increasing construction complexity, line losses, and operation and maintenance costs.

[0003] In ground-mounted photovoltaic power plants, industrial rooftop photovoltaic systems, desert photovoltaic power plants, and photovoltaic scenarios in high-temperature regions, the back side of photovoltaic modules typically creates a high-temperature environment. Ordinary lithium-ion batteries, especially energy storage batteries designed for room temperature or medium-low temperature operation, are not suitable for long-term operation in close proximity to the high-temperature areas on the back of photovoltaic modules or photovoltaic supports. Therefore, current technologies typically keep energy storage systems away from photovoltaic modules and maintain battery operating temperatures through independent air conditioning, liquid cooling, or air cooling systems.

[0004] Sulphurized polyacrylonitrile (SPAN) batteries exhibit a different active sulfur binding morphology compared to traditional carbon-sulfur lithium-sulfur batteries. Their active sulfur exists in a chemically bonded or structurally constrained form, resulting in better high-temperature adaptability and low shuttle characteristics. Using SPAN batteries for distributed energy storage on the back side of photovoltaic modules can fully utilize the space on the back of the photovoltaic module, the back of the support structure, and the interior of the support structure, reducing the independent footprint of traditional energy storage containers and improving the integration level of the photovoltaic energy storage system. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the purpose of this invention is to provide a distributed energy storage system based on SPAN batteries and its control method.

[0006] This invention enables energy storage modules to be distributed and installed on the back side of photovoltaic modules or within the photovoltaic support structure, and to operate directly, derated, or safely isolated in the high-temperature environment formed on the back side of photovoltaic modules. This reduces the footprint of independent energy storage, shortens connecting cables, reduces the complexity of system construction, and improves the space utilization of photovoltaic energy storage systems.

[0007] A distributed energy storage system based on SPAN batteries includes:

[0008] At least one photovoltaic support frame, on the upper part of which photovoltaic modules are installed;

[0009] An integrated SPAN energy storage module is installed on the photovoltaic support near the back of the photovoltaic module;

[0010] The integrated SPAN energy storage module includes at least one battery cell with sulfurized polyacrylonitrile as the positive electrode active material.

[0011] The integrated SPAN energy storage module is connected to the DC converter via a DC combiner box or DC bus.

[0012] The DC converter is connected to an energy storage inverter or a grid-connected inverter, and is connected to the power grid or load through the energy storage inverter or grid-connected inverter.

[0013] The EMS management unit or energy management unit performs energy dispatching on the system based on photovoltaic output, grid status, load demand, and energy storage module status.

[0014] In a preferred embodiment of the present invention, a ventilation gap is provided between the integrated SPAN energy storage module and the photovoltaic module, forming air convection within the ventilation gap. The distance of the ventilation gap is 5-100mm.

[0015] In a preferred embodiment of the present invention, the integrated SPAN energy storage module includes a metal housing, and an SPAN battery pack or SPAN energy storage unit is disposed in the inner mounting cavity of the metal housing.

[0016] A heat insulation layer is provided between individual adjacent cells of the SPAN battery pack or SPAN energy storage unit.

[0017] An energy storage BMS module or battery management unit, a protection unit or fuse, a contactor or protective switch, a voltage sampling unit, a current sampling unit and an insulation detection unit, a temperature sensor, a communication interface, a waterproof electrical connector and a pressure relief structure are provided in the mounting cavity inside the metal casing.

[0018] The positive and negative terminals of the SPAN battery pack or SPAN energy storage unit are connected to the DC combiner box or DC bus via a protection unit or fuse, contactor or protective switch and waterproof electrical connector to form the main power circuit.

[0019] The waterproof electrical connector can be configured as a pluggable connector, allowing the integrated SPAN energy storage module to be disassembled along the guide rail after the main power circuit is disconnected and the lock is released, thereby enabling independent maintenance or replacement of a single module.

[0020] The temperature sensor, voltage sampling unit, current sampling unit, and insulation detection unit are connected to the energy storage BMS module to form a sampling and detection loop.

[0021] The energy storage BMS module communicates with the EMS management unit through a communication interface to form a control communication loop.

[0022] The EMS management unit receives the module status uploaded by the energy storage BMS module, and, in conjunction with photovoltaic output, grid status, and load demand, issues energy dispatch or operation mode control commands to the energy storage BMS module, DC converter, and energy storage inverter or grid-connected inverter.

[0023] The energy storage BMS module or battery management unit collects the individual cell voltage, module voltage, current, temperature, insulation status, state of charge, and health status of the SPAN battery pack or SPAN energy storage unit, and performs equalization, protection, current limiting, temperature derating, fault isolation, bypass, or restoration access control based on the parameters.

[0024] In a preferred embodiment of the present invention, the integrated SPAN energy storage module is mounted on the photovoltaic bracket via a back support and mounting rail.

[0025] In a preferred embodiment of the present invention, multiple integrated SPAN energy storage modules are connected in parallel to a low-voltage DC bus or a DC combiner box. The low-voltage DC bus or DC combiner box is connected to a high-voltage DC bus via a bidirectional DC converter, and then connected to the power grid or load via an energy storage inverter or a grid-connected inverter.

[0026] In a preferred embodiment of the present invention, the plurality of integrated SPAN energy storage modules can be connected to the high-voltage DC bus via corresponding DC converters, and output electrical energy to the grid or load through energy storage inverters or grid-connected inverters.

[0027] In a preferred embodiment of the present invention, the outer periphery of the integrated SPAN energy storage module is provided with a heat insulation layer.

[0028] A control method for a distributed energy storage system based on SPAN batteries, comprising:

[0029] S1, the energy storage BMS module or battery management unit collects the temperature data and operating status data of the integrated SPAN energy storage module;

[0030] S2, determine whether the temperature data exceeds the first-level threshold, and if so, execute the first-level power derating;

[0031] S3, determine whether the temperature data after the first-level power derating exceeds the second-level threshold; if so, execute the second-level power derating.

[0032] S4. Determine whether the fault isolation condition has been met. If so, disconnect the specific faulty integrated SPAN energy storage module and report the alarm information to the EMS management unit or energy management unit. At the same time, maintain the continuous operation of the remaining unfaulty integrated SPAN energy storage modules and continuously monitor the temperature recovery of the faulty integrated SPAN energy storage module.

[0033] S5, determine whether the temperature recovery of the faulty integrated SPAN energy storage module meets the restoration access conditions. If it does, restore the faulty integrated SPAN energy storage module to system operation.

[0034] In a preferred embodiment of the present invention, the access restoration condition is:

[0035] If the module temperature of the fault-integrated SPAN energy storage module is lower than the preset recovery temperature threshold and continues for a preset recovery time, and the individual cell voltage, module voltage, current, insulation status, state of charge, and health status are all within the allowable range, the energy storage BMS module self-test passes, and the EMS management unit allows restoration of access.

[0036] Before reconnection, pre-charge detection, communication status detection, and contactor status detection are performed. If any detection fails, the faulty integrated SPAN energy storage module is kept isolated and the alarm is maintained. When the detection passes, the control contactor or protection switch is closed, allowing the faulty integrated SPAN energy storage module to resume access to the system.

[0037] The beneficial effects of this invention are as follows:

[0038] Compared with existing containerized energy storage systems, the present invention has a smaller footprint and makes full use of the space on the back and side of the photovoltaic modules and the support structure, transforming the originally idle structural space into energy storage installation space.

[0039] By placing energy storage modules close to photovoltaic modules or photovoltaic subarrays, the connection path between the photovoltaic array and the energy storage module can be shortened, thereby reducing cable length and line loss.

[0040] By leveraging the adaptability of SPAN batteries to high-temperature environments, energy storage modules can operate directly, derating, or safely isolated in high-temperature environments on the back side of photovoltaics, and individual energy storage modules can be replaced independently.

[0041] Local isolation of energy storage modules reduces the risk of overall system downtime in the event of a fault. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the system connection of the present invention.

[0043] Figure 2 This is a schematic diagram of the overall structure of the present invention.

[0044] Figure 3 This is a schematic diagram of the integrated SPAN energy storage module 200 of the present invention.

[0045] Figure 4 This is a schematic diagram of the control method of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, in the following descriptions, well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention.

[0047] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] A distributed energy storage system based on SPAN batteries includes a photovoltaic support 100, on the upper part of which photovoltaic modules 110 are installed.

[0049] An integrated SPAN energy storage module 200 is installed on the back side 120 of the photovoltaic bracket 100 near the photovoltaic module 110.

[0050] The integrated SPAN energy storage module includes at least one battery cell with sulfurized polyacrylonitrile as the positive electrode active material.

[0051] The individual cells in the integrated SPAN energy storage module 200 operate at voltages ranging from 1.0V to 3.0V. Each individual cell is a minimal battery element, and the integrated SPAN energy storage module 200 is composed of multiple cells connected in series and parallel; its voltage depends on the number of cells connected in series and parallel.

[0052] In this embodiment, the photovoltaic module 110 can be a photovoltaic module or a photovoltaic subarray.

[0053] The integrated SPAN energy storage module 200 is installed on the photovoltaic bracket 100 by means of a back support (such as a mounting bracket 210, a first connecting structure 211 and a second connecting structure 212) and a mounting rail 220.

[0054] The integrated SPAN energy storage module 200 has an insulation layer on its outer periphery.

[0055] The insulation layer can be a reflective insulation layer, a metal reflective layer, a mica layer, a ceramic fiber layer, an aerogel insulation layer, a flame-retardant insulation board, or an insulation coating.

[0056] A ventilation gap 130 is provided between the integrated SPAN energy storage module 200 and the photovoltaic module 110, and air convection is formed within the ventilation gap.

[0057] The ventilation gap can be from 5 mm to 100 mm, preferably from 10 mm to 50 mm, and more preferably from 20 mm to 30 mm.

[0058] The integrated SPAN energy storage module 200 is connected to the DC converter 400 via a DC combiner box or DC bus 300.

[0059] In the low-voltage distributed implementation, multiple integrated SPAN energy storage modules are connected in parallel to the low-voltage DC bus or DC combiner box. The low-voltage DC bus or DC combiner box is connected to the high-voltage DC bus via a bidirectional DC converter, and then connected to the grid or load 700 through the energy storage inverter or grid-connected inverter 500.

[0060] The low-voltage DC bus 310 includes 48V, 96V, 150V or other low-voltage DC buses.

[0061] This embodiment is applicable to 48V, 96V, 150V or other low-voltage DC energy storage architectures, and can be used for distributed photovoltaic, rooftop photovoltaic, off-grid photovoltaic or low-voltage DC microgrid.

[0062] In the high-voltage direct current embodiment, multiple integrated SPAN energy storage modules can be connected to the high-voltage direct current bus via corresponding DC converters, and output electrical energy to the grid or load through energy storage inverters or grid-connected inverters.

[0063] The 320 high-voltage DC bus includes 300V, 400V, 600V, 750V, 1000V or 1500V DC bus.

[0064] The DC converter of the present invention is connected to an energy storage inverter or a grid-connected inverter, and is connected to the power grid or load through the energy storage inverter or grid-connected inverter.

[0065] The EMS management unit or energy management unit 600 performs energy dispatching on the system based on photovoltaic output, grid status, load demand, and energy storage module status.

[0066] The integrated SPAN energy storage module 200 includes a metal housing 201, and a SPAN battery pack or SPAN energy storage unit 202 is provided in the inner mounting cavity of the metal housing. A heat insulation layer is provided on the outer periphery of the SPAN battery pack or SPAN energy storage unit.

[0067] Additionally, a heat insulation layer is provided between adjacent individual battery structures in the SPAN battery pack or SPAN energy storage unit.

[0068] An energy storage BMS module 203 or battery management unit, a protection unit or fuse 204, a contactor or protective switch 205, a temperature sensor 206, a communication interface 207, a waterproof electrical connector 208, and a pressure relief structure 209 are provided in the mounting cavity inside the metal casing.

[0069] The positive and negative terminals of the SPAN battery pack or SPAN energy storage unit are connected to the DC combiner box or DC bus via a protection unit or fuse, contactor or protective switch and waterproof electrical connector to form the main power circuit.

[0070] The waterproof electrical connector can be configured as a pluggable connector, allowing the integrated SPAN energy storage module to be disassembled along the guide rail after the main power circuit is disconnected and the lock is released, thereby enabling independent maintenance or replacement of a single module.

[0071] The temperature sensor, voltage sampling unit, current sampling unit, and insulation detection unit are connected to the energy storage BMS module to form a sampling and detection loop.

[0072] The energy storage BMS module communicates with the EMS management unit through a communication interface to form a control communication loop.

[0073] The energy storage BMS module collects data on the individual cell voltage, module voltage, current, temperature, insulation status, state of charge, and health status of the SPAN battery pack, and performs equalization, protection, current limiting, temperature derating, fault isolation, bypass, or recovery control based on the collected parameters.

[0074] The EMS management unit receives the module status uploaded by the energy storage BMS module, and, in conjunction with photovoltaic output, grid status, and load demand, issues energy dispatch or operation mode control commands to the energy storage BMS module, DC converter, and energy storage inverter or grid-connected inverter.

[0075] The energy storage BMS module or battery management unit collects the individual cell voltage, module voltage, current, temperature, insulation status, state of charge, and health status of the SPAN battery pack or SPAN energy storage unit, and performs equalization, protection, current limiting, temperature derating, fault isolation, bypass, or restoration access control based on the relevant parameters.

[0076] The specific control method is as follows: a control method for a distributed energy storage system based on SPAN batteries, including:

[0077] S1, the energy storage BMS module or battery management unit collects the temperature data and operating status data of the integrated SPAN energy storage module;

[0078] S2, determine whether the temperature data exceeds the first-level threshold, and if so, execute the first-level power derating;

[0079] S3, determine whether the temperature data after the first-level power derating exceeds the second-level threshold; if so, execute the second-level power derating.

[0080] S4. Determine whether the fault isolation condition has been met. If so, disconnect the specific faulty integrated SPAN energy storage module and report the alarm information to the EMS management unit or energy management unit. At the same time, maintain the continuous operation of the remaining unfaulty integrated SPAN energy storage modules and continuously monitor the temperature recovery of the faulty integrated SPAN energy storage module.

[0081] S5, determine whether the temperature recovery of the faulty integrated SPAN energy storage module meets the restoration access conditions. If it does, restore the faulty integrated SPAN energy storage module to system operation.

[0082] The conditions for restoring access are:

[0083] If the module temperature of the fault-integrated SPAN energy storage module is lower than the preset recovery temperature threshold and continues for a preset recovery time, and the individual cell voltage, module voltage, current, insulation status, state of charge, and health status are all within the allowable range, the energy storage BMS module self-test passes, and the EMS management unit allows restoration of access.

[0084] Before reconnection, pre-charge detection, communication status detection, and contactor status detection are performed. If any detection fails, the faulty integrated SPAN energy storage module is kept isolated and the alarm is maintained. When the detection passes, the control contactor or protection switch is closed, allowing the faulty integrated SPAN energy storage module to resume access to the system.

[0085] The foregoing has shown and described the basic principles and main features of the invention and the advantages of the invention.

[0086] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A distributed energy storage system based on SPAN batteries, characterized in that, include: At least one photovoltaic support frame, on the upper part of which photovoltaic modules are installed; An integrated SPAN energy storage module is installed on the photovoltaic support near the back of the photovoltaic module; The integrated SPAN energy storage module includes at least one battery cell with sulfurized polyacrylonitrile as the positive electrode active material. The DC converter is connected via a DC combiner box or DC bus. The DC converter is connected to an energy storage inverter or a grid-connected inverter, and is connected to the power grid or load through the energy storage inverter or grid-connected inverter. The EMS management unit or energy management unit performs energy dispatching on the system based on photovoltaic output, grid status, load demand, and energy storage module status.

2. The distributed energy storage system based on SPAN batteries as described in claim 1, characterized in that, A ventilation gap is provided between the integrated SPAN energy storage module and the photovoltaic module, forming air convection within the ventilation gap. The distance of the ventilation gap is 5-100mm.

3. A distributed energy storage system based on SPAN batteries as described in claim 1, characterized in that, The integrated SPAN energy storage module includes a metal casing, and an SPAN battery pack or SPAN energy storage unit is disposed in the mounting cavity inside the metal casing. A heat insulation layer is provided between individual adjacent cells of the SPAN battery pack or SPAN energy storage unit. An energy storage BMS module or battery management unit, a protection unit or fuse, a contactor or protective switch, a voltage sampling unit, a current sampling unit and an insulation detection unit, a temperature sensor, a communication interface, a waterproof electrical connector and a pressure relief structure are provided in the inner mounting cavity of the metal casing. The positive and negative terminals of the SPAN battery pack or SPAN energy storage unit are connected to the DC combiner box or DC bus via a protection unit or fuse, contactor or protection switch and waterproof electrical connector to form the main power circuit. The waterproof electrical connector can be configured as a pluggable connector. The temperature sensor, voltage sampling unit, current sampling unit, and insulation detection unit are respectively connected to the energy storage BMS module to form a sampling and detection loop; The energy storage BMS module communicates with the EMS management unit through a communication interface to form a control communication loop; The EMS management unit receives the module status uploaded by the energy storage BMS module, and, in conjunction with the photovoltaic output, grid status and load demand, issues energy dispatch or operation mode control commands to the energy storage BMS module, DC converter and energy storage inverter or grid-connected inverter. The energy storage BMS module or battery management unit collects the individual cell voltage, module voltage, current, temperature, insulation status, state of charge, and health status of the SPAN battery pack or SPAN energy storage unit, and performs equalization, protection, current limiting, temperature derating, fault isolation, bypass, or restoration access control based on the parameters.

4. A distributed energy storage system based on SPAN batteries as described in claim 1, characterized in that, The integrated SPAN energy storage module is mounted on the photovoltaic bracket using a back support and mounting rails.

5. A distributed energy storage system based on SPAN batteries as described in claim 1, characterized in that, Multiple integrated SPAN energy storage modules are connected in parallel to a low-voltage DC bus or a DC combiner box. The low-voltage DC bus or DC combiner box is connected to a high-voltage DC bus via a bidirectional DC converter, and then connected to the power grid or load via an energy storage inverter or a grid-connected inverter.

6. A distributed energy storage system based on SPAN batteries as described in claim 1, characterized in that, Multiple integrated SPAN energy storage modules can be connected to the high-voltage DC bus via corresponding DC converters, and output electrical energy to the grid or load through energy storage inverters or grid-connected inverters.

7. A distributed energy storage system based on SPAN batteries as described in claim 1, characterized in that, The integrated SPAN energy storage module is provided with a heat insulation layer on its outer periphery.

8. The control method for a distributed energy storage system based on SPAN batteries as described in any one of claims 1-7, characterized in that, include: S1, the energy storage BMS module or battery management unit collects the temperature data and operating status data of the integrated SPAN energy storage module; S2, determine whether the temperature data exceeds the first-level threshold, and if so, execute the first-level power derating; S3, determine whether the temperature data after the first-level power derating exceeds the second-level threshold; if so, execute the second-level power derating. S4. Determine whether the fault isolation condition has been met. If so, disconnect the specific faulty integrated SPAN energy storage module and report the alarm information to the EMS management unit or energy management unit. At the same time, maintain the continuous operation of the remaining unfaulty integrated SPAN energy storage modules and continuously monitor the temperature recovery of the faulty integrated SPAN energy storage module. S5, determine whether the temperature recovery of the faulty integrated SPAN energy storage module meets the restoration access conditions. If it does, restore the faulty integrated SPAN energy storage module to system operation.

9. The control method for a distributed energy storage system based on SPAN batteries as described in claim 8, characterized in that, The conditions for restoring access are as follows: If the module temperature of the fault-integrated SPAN energy storage module is lower than the preset recovery temperature threshold and continues for a preset recovery time, and the individual cell voltage, module voltage, current, insulation status, state of charge, and health status are all within the allowable range, the energy storage BMS module self-test passes, and the EMS management unit allows restoration of access.

10. The control method for a distributed energy storage system based on SPAN batteries as described in claim 8, characterized in that, Before reconnection, pre-charge detection, communication status detection, and contactor status detection are performed. If any detection fails, the faulty integrated SPAN energy storage module is kept isolated and the alarm is maintained. When the detection passes, the control contactor or protection switch is closed, allowing the faulty integrated SPAN energy storage module to resume access to the system.

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