A photovoltaic microgrid device based on battery + super capacitor hybrid energy storage

Abstract

The utility model discloses a kind of photovoltaic microgrid devices based on battery+super capacitor hybrid energy storage, it is related to new energy storage technology field, comprising: photovoltaic module, energy storage component, heat dissipation component and junction box;The energy storage component includes: battery pack and super capacitor group;The heat dissipation component includes: heat dissipation layer and heat dissipation fan, the heat dissipation layer is between battery pack and super capacitor group, and the heat dissipation fan is located in the side of heat dissipation layer;The junction box and photovoltaic module are set to the top of super capacitor group, and the photovoltaic module and energy storage component are connected with direct current bus through junction box, and the junction box is connected with microgrid.The utility model has the advantages that the advantages of battery and super capacitor are considered, the charge-discharge state of energy storage equipment can be dynamically adjusted according to power demand and energy supply condition, efficient energy storage and release are realized, and the stability and reliability of photovoltaic microgrid system are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to new energy storage technology field, concretely relates to a photovoltaic microgrid device based on battery + supercapacitor hybrid energy storage. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and can not constitute the prior art.

[0003] In the microgrid system technical field, photovoltaic power generation as the core unit of distributed energy, its output power is significantly influenced by external factors such as solar irradiance, ambient temperature and cloud cover, resulting in strong randomness and uncontrollability of power generation curve. This intermittent power supply characteristic makes the microgrid system face the operation risks of active power instantaneous imbalance, bus voltage fluctuation and frequency deviation, especially under the working conditions of drastic change of illumination conditions or sudden increase and decrease of load, the system dynamic adjustment capacity faces severe test.

[0004] In order to suppress photovoltaic power fluctuation, the existing technology generally uses energy storage device as energy buffer unit. Among them, the electrochemical energy storage technology represented by lithium ion battery and lead-acid battery is widely used in medium and long term energy storage due to its high energy density (usually 100-300 Wh / kg) and stable continuous discharge capacity. However, limited by its inherent electrochemical reaction kinetics characteristics, the power density of battery is usually less than 500 W / kg, resulting in problems such as charge-discharge response delay (typical response time is seconds) and capacity attenuation acceleration under large current working condition when dealing with power fluctuation in seconds to minutes. In addition, the cycle life of battery is obviously restricted by the depth of discharge (DOD). When DOD exceeds 80%, the cycle number of lithium ion battery will be reduced to less than 2000 times, which significantly increases the system maintenance cost.

[0005] On the other hand, the physical energy storage technology represented by double-layer supercapacitor realizes charge storage relying on electrostatic adsorption mechanism, has the advantages of high power density (can reach more than 10 kW / kg), charge-discharge efficiency more than 95% and cycle life more than 500000 times, and can quickly respond to millisecond level power fluctuation. But its energy density is usually less than 10 Wh / kg, and the single energy storage capacity is limited, which cannot support the continuous power supply demand of microgrid in rainy weather or night and other zero output scenarios of photovoltaic. If pure supercapacitor is used to build energy storage system, the number of parallel modules needs to be increased greatly, resulting in large equipment size, cost increase and complex multi-module current sharing control problem.

[0006] The prior art attempts to use a battery and super capacitor hybrid energy storage scheme to balance the energy density and power density requirements. However, the scheme exposes the following technical bottlenecks in practical application: first, the energy management strategy of the hybrid energy storage system is mostly based on fixed thresholds or simple rule control, which is difficult to adapt to the dynamic coupling characteristics of photovoltaic output and load demand, easily leading to improper power distribution between energy storage units, causing the battery to frequently withstand high-rate charging and discharging impact and accelerate aging, or the super capacitor to be in a long-term shallow charging and discharging state, causing capacity waste; second, the voltage characteristics of the battery and the super capacitor need to rely on a bidirectional DC / DC converter to realize interface matching, and the introduction of multi-stage power electronic devices not only increases system loss (additional loss can reach 5%-8%), but also causes dynamic response performance to deteriorate due to control loop delay; in addition, the existing hybrid energy storage system lacks real-time perception and adaptive regulation mechanism for the health state of the energy storage units, and cannot dynamically optimize the energy storage ratio during system operation, resulting in low equipment utilization and insufficient full life cycle economy. The above problems seriously restrict the energy consumption capacity and operation reliability of the micro-grid system for photovoltaic fluctuation energy. Practical new type content

[0007] The utility model in related to the traditional photovoltaic micro-grid device, and the single energy storage device has the insufficiency, and puts forward a kind of hybrid energy storage scheme combining battery and super capacitor. Specific purposes include:

[0008] 1. Solve the performance limitation problem of single energy storage device

[0009] In the traditional photovoltaic micro-grid, if only battery energy storage is used, more electric energy can be stored, but sudden high-power load cannot be quickly responded. If only super capacitor energy storage is used, although it can be quickly charged and discharged, it is difficult to maintain long-term stable power supply. The utility model combines battery pack and super capacitor pack for use, so that the two kinds of energy storage devices are complementary in energy density and power density, which meets the daily continuous power supply demand and can respond to instantaneous power fluctuation.

[0010] 2. Prolong the service life of energy storage device

[0011] In the traditional scheme, the battery is prone to shorten the service life due to frequent charging and discharging, and the super capacitor may also be damaged if it is in a high load state for a long time. The utility model uses a hybrid energy storage structure, so that the battery mainly undertakes the task of long-term charging and discharging, and the super capacitor is responsible for short-time high-current charging and discharging, thereby reducing the damage of the two types of devices and prolonging the overall service life.

[0012] 3. Improve the heat dissipation efficiency and operation stability of the device

[0013] In existing energy storage devices, the centralized arrangement of batteries and supercapacitors can easily lead to heat accumulation, affecting performance. This invention addresses this issue by installing a heat dissipation layer with ventilation holes between the battery pack and the supercapacitor pack, and configuring a cooling fan to actively guide airflow, accelerating heat dissipation, ensuring the equipment operates at a suitable temperature, and avoiding the risk of failure due to overheating.

[0014] The technical solution of this utility model is as follows:

[0015] A photovoltaic microgrid device based on hybrid energy storage of batteries and supercapacitors includes:

[0016] Photovoltaic modules, energy storage modules, heat dissipation modules, and junction boxes;

[0017] The energy storage components include: a battery pack and a supercapacitor pack;

[0018] The heat dissipation component includes: a heat dissipation layer and a heat dissipation fan, wherein the heat dissipation layer is located between the battery pack and the supercapacitor pack, and the heat dissipation fan is located on one side of the heat dissipation layer;

[0019] The junction box and photovoltaic modules are located on top of the supercapacitor bank. The photovoltaic modules and energy storage modules are connected to the DC bus through the junction box, which is also connected to the microgrid.

[0020] Furthermore, the junction box includes a DC bus, a Boost converter, a DC / AC inverter, and two bidirectional Buck-Boost converters connected to the battery pack and the supercapacitor pack, respectively.

[0021] Furthermore, the heat dissipation layer has several horizontally oriented heat dissipation holes inside, and the side with the heat dissipation holes is connected to the air inlet of the heat dissipation fan.

[0022] Furthermore, the photovoltaic module is connected to the DC bus via a Boost converter; the input of the Boost converter is connected to the photovoltaic module, and the output is connected to the DC bus.

[0023] Furthermore, the battery pack is connected to the DC bus via a first bidirectional Buck-Boost converter, and the supercapacitor pack is connected to the DC bus via a second bidirectional Buck-Boost converter.

[0024] Furthermore, the DC bus is connected to the microgrid and the cooling fan respectively through a DC / AC inverter. The input terminal of the DC / AC inverter is connected to the DC bus, and the output terminal is connected to the power supply terminals of the microgrid and the cooling fan respectively.

[0025] Furthermore, the main circuit of the first bidirectional Buck-Boost converter includes: a power switching device V1, an inductor L1, and a capacitor C1 connected in series; the battery pack is connected in parallel across the capacitor C1; the power switching device V2 is connected in parallel between the connection node of the inductor L1 and the capacitor C1; and diodes D1 and D2 are connected in reverse parallel across the power switching devices V1 and V2, respectively.

[0026] Furthermore, the main circuit of the second bidirectional Buck-Boost converter includes: a power switching device V3, an inductor L2 and a supercapacitor bank connected in series, a power switching device V4 connected in parallel between the connection node of the inductor L2 and the supercapacitor bank, and diodes D3 and D4 connected in reverse parallel across the two ends of the power switching devices V3 and V4, respectively.

[0027] Furthermore, the heat dissipation layer, the battery pack, and the supercapacitor pack are all installed in close contact, with the battery pack located on the lower side of the heat dissipation layer and the supercapacitor pack located on the upper side of the heat dissipation layer.

[0028] Furthermore, the junction box is provided with a live wire terminal and a neutral wire terminal on its side, and the live wire terminal and the neutral wire terminal are respectively connected to the AC output terminal of the DC / AC inverter and the microgrid via wires.

[0029] Compared with existing technologies, the beneficial effects of this utility model are:

[0030] 1. This utility model utilizes a hybrid energy storage structure combining a battery bank and a supercapacitor bank, enabling dynamic division of labor between the two energy storage media: the supercapacitor bank, leveraging its high power density, rapidly responds to sudden high-power load demands from the microgrid, while the battery bank, relying on its high energy density, continuously provides stable power output. This dual support mechanism effectively suppresses transient grid impacts through the rapid discharge of the supercapacitor, while ensuring long-term energy supply through the continuous power supply of the battery, thereby significantly balancing the difference between short-term power demand and long-term energy reserves, and improving the operational stability of the microgrid system.

[0031] 2. This utility model's device dynamically allocates the charging and discharging tasks of the battery and supercapacitor, prioritizing high-frequency, low-depth charging and discharging operations to the supercapacitor, while assigning low-frequency, high-depth charging and discharging tasks to the battery. This division of labor strategy fully leverages the cycle life advantage of the supercapacitor, while significantly reducing the charging and discharging frequency of the battery, thereby extending the overall service life of the hybrid energy storage system and reducing system maintenance costs.

[0032] 3. The device of this utility model also maintains the operating temperature of the battery pack and supercapacitor pack within a suitable range through the synergistic effect of the heat dissipation layer and the heat dissipation fan, effectively avoiding the adverse effects of high temperature environment on the performance of energy storage equipment, and further improving the reliability and service life of the equipment. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors.

[0034] Figure 2 This is a schematic diagram of the heat dissipation layer in a photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors.

[0035] Figure 3 This is a microgrid system connection diagram based on a photovoltaic microgrid device with hybrid energy storage of batteries and supercapacitors;

[0036] Figure 4 This is a main circuit diagram of an energy storage component for a photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors.

[0037] Figure label:

[0038] 1-Photovoltaic module, 2-Energy storage module, 3-Heat dissipation module, 4-Gathering box;

[0039] 21-Battery pack, 22-Supercapacitor pack;

[0040] 31-Heat dissipation layer, 32-Heat dissipation fan, 311-Heat dissipation hole;

[0041] 41-Live wire terminal, 42-Neutral wire terminal. Detailed Implementation

[0042] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0043] The features and performance of this utility model will be further described in detail below with reference to the embodiments.

[0044] Example 1

[0045] This embodiment proposes a photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors, aiming to overcome the shortcomings of traditional photovoltaic microgrid devices in terms of short-term and long-term energy supply. This device integrates battery and supercapacitor energy storage technologies, possessing both high power and high capacity performance, achieving efficient energy storage and release, thereby improving the energy utilization efficiency and stability of the microgrid.

[0046] To achieve the above objectives, this embodiment provides the following technical solution:

[0047] Please see Figure 1 A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors includes:

[0048] Photovoltaic module 1, energy storage module 2, heat dissipation module 3, and junction box 4;

[0049] The energy storage component 2 includes: a battery pack 21 and a supercapacitor pack 22;

[0050] The heat dissipation component 3 includes: a heat dissipation layer 31 and a heat dissipation fan 32. The heat dissipation layer 31 is located between the battery pack 21 and the supercapacitor pack 22, and the heat dissipation fan 32 is located on one side of the heat dissipation layer 31.

[0051] The junction box 4 and the photovoltaic module 1 are located on top of the supercapacitor bank 22. The photovoltaic module 1 and the energy storage module 2 are connected to the DC bus through the junction box 4, and the junction box 4 is connected to the microgrid.

[0052] In this embodiment, the junction box 4 specifically includes a DC bus, a Boost converter, a DC / AC inverter, and two bidirectional Buck-Boost converters that are respectively connected to the battery pack 21 and the supercapacitor pack 22.

[0053] In this embodiment, specifically, such as Figure 2 As shown, the heat dissipation layer 31 has several horizontal heat dissipation holes 311 inside, and the side with the heat dissipation holes 311 is connected to the air inlet of the heat dissipation fan 32.

[0054] In this embodiment, specifically, such as Figure 3 As shown, the photovoltaic module 1 is connected to the DC bus via a Boost converter; the input terminal of the Boost converter is connected to the photovoltaic module 1, and the output terminal is connected to the DC bus.

[0055] In this embodiment, specifically, the battery pack 21 is connected to the DC bus via a first bidirectional Buck-Boost converter, and the supercapacitor pack 22 is connected to the DC bus via a second bidirectional Buck-Boost converter.

[0056] In this embodiment, the DC bus is specifically connected to the microgrid and the cooling fan 32 via a DC / AC inverter. The input terminal of the DC / AC inverter is connected to the DC bus, and the output terminal is connected to the power supply terminals of the microgrid and the cooling fan 32.

[0057] In this embodiment, please refer to Figure 4 The specific implementation of the main circuit of the first bidirectional Buck-Boost converter is as follows:

[0058] The power switching device V1, inductor L1, and capacitor C1 are connected in series. The battery pack 21 is connected in parallel across capacitor C1. The power switching device V2 is connected in parallel between the connection node of inductor L1 and capacitor C1. Diodes D1 and D2 are connected in reverse parallel across power switching devices V1 and V2, respectively.

[0059] The power switching device V1, inductor L1 and capacitor C1 are connected in series and then in parallel to the DC bus. The battery pack 21 is connected in parallel across capacitor C1. The power switching device V2 is connected in parallel across L1 and C1. Diodes D1 and D2 are connected in reverse parallel across power switching devices V1 and V2, respectively.

[0060] In this embodiment, please refer to Figure 4 The specific implementation of the main circuit of the second bidirectional Buck-Boost converter is as follows:

[0061] The power switching device V3, inductor L2, and supercapacitor bank 22 are connected in series. The power switching device V4 is connected in parallel between the connection node of inductor L2 and supercapacitor bank 22. Diodes D3 and D4 are connected in reverse parallel across the two ends of the power switching devices V3 and V4, respectively.

[0062] The power switching device V3, inductor L2 and supercapacitor bank 22 will be connected in series and then in parallel to the DC bus. The power switching device V4 will be connected in parallel across L2 and the supercapacitor bank 22. Diodes D3 and D4 will be connected in reverse parallel across the power switching devices V3 and V4, respectively.

[0063] In this embodiment, specifically, the heat dissipation layer 31, the battery pack 21, and the supercapacitor pack 22 are all installed in close contact, with the battery pack 21 located on the lower side of the heat dissipation layer 31 and the supercapacitor pack 22 located on the upper side of the heat dissipation layer 31.

[0064] In this embodiment, specifically, the junction box 4 is provided with a live wire terminal 41 and a neutral wire terminal 42 on its side. The live wire terminal 41 and the neutral wire terminal 42 are respectively connected to the AC output terminal of the DC / AC inverter and the microgrid through wires.

[0065] In this embodiment, it should also be noted that the specific workflow of the photovoltaic microgrid device based on hybrid energy storage of batteries and supercapacitors proposed in this embodiment is as follows:

[0066] Photovoltaic module 1 begins generating electricity under suitable sunlight conditions, and the DC power is converted to the required voltage level by the Boost converter inside junction box 4, and then connected to the DC bus. Part of the electricity is directly supplied to the microgrid to meet its immediate power demand; while the other part of the electricity is distributed to energy storage module 2 for storage.

[0067] The battery pack 21 is responsible for long-term energy storage, enabling the device to meet power demands over extended periods. Meanwhile, the supercapacitor pack 22 is responsible for short-term energy storage, featuring rapid charge and discharge capabilities, thus allowing for the quick release of stored energy to meet sudden load demands.

[0068] The Boost converter and bidirectional Buck-Boost converter inside junction box 4 dynamically adjust the power output of energy storage component 2 according to the real-time demand of the microgrid. This ensures that the microgrid can quickly obtain the required power when facing sudden load demands, while balancing the power supply and demand of the microgrid.

[0069] The cooling fan 32 is controlled according to the temperature within the heat dissipation layer 31, and dissipates the generated heat through the heat dissipation holes 311 to ensure that the device maintains a normal operating temperature during operation. This helps improve the stability and reliability of the system and avoids failures caused by overheating.

[0070] Finally, the DC bus converts the DC power to AC power via a DC / AC inverter, and then connects it to the microgrid to meet the microgrid's power needs. Through this workflow, the device can effectively utilize the electrical energy generated by the photovoltaic power generation system, and combine it with hybrid energy storage technology of batteries and supercapacitors to improve energy utilization efficiency, cope with daily and sudden energy fluctuations, and thus enhance the stability and reliability of the microgrid.

[0071] Example 2

[0072] Example 2 is based on the photovoltaic microgrid device based on hybrid energy storage of battery and supercapacitor proposed in Example 1, and also proposes a dynamic adjustment mechanism for battery pack and supercapacitor pack.

[0073] In this embodiment, specifically, the dynamic adjustment mechanism of the battery pack and supercapacitor pack is manifested as follows:

[0074] When the microgrid load suddenly increases (e.g., motor starting, welding equipment connection), the second bidirectional Buck-Boost converter prioritizes controlling the supercapacitor bank to release a large current within tens of milliseconds, while the first bidirectional Buck-Boost converter keeps the battery bank in standby mode. When the load demand continuously exceeds the supercapacitor's power supply capacity, the battery bank gradually increases its output power through the first bidirectional Buck-Boost converter to achieve a smooth switching. This coordinated control method avoids the plate sulfation problem caused by the battery directly bearing the current surge in traditional solutions, and also prevents voltage drops caused by over-discharge of the supercapacitor. (Example 3)

[0075] Example 3 is based on the photovoltaic microgrid device based on hybrid energy storage of battery and supercapacitor proposed in Example 1, and also proposes the operation logic of heat dissipation component.

[0076] In this embodiment, the operating logic of the heat dissipation component is further refined as follows:

[0077] When the battery pack is charging, the heat generated by the internal chemical reaction is conducted laterally through the heat dissipation layer that is installed in close contact with the battery. At this time, the cooling fan automatically increases its speed according to the signal of the thermal sensor and concentrates the heat to be discharged from the heat dissipation holes.

[0078] When the supercapacitor bank undergoes high-frequency charging and discharging, the heat dissipation layer preferentially conducts Joule heat from inside the capacitor to the battery side, forming a two-way thermal equilibrium path. Compared with traditional independent heat dissipation solutions, this heat distribution strategy can reduce fan energy consumption by about 30%.

[0079] Example 4

[0080] Example 4 further illustrates the control characteristics of the bidirectional Buck-Boost converter based on a photovoltaic microgrid device with hybrid energy storage of battery and supercapacitor proposed in Example 1.

[0081] In this embodiment, the specific control characteristics of the bidirectional Buck-Boost converter are as follows:

[0082] The first bidirectional Buck-Boost converter adopts dual closed-loop control with an outer voltage loop and an inner current loop to maintain a stable DC bus voltage during battery charging and discharging.

[0083] The second bidirectional Buck-Boost converter adopts a direct power control mode, which achieves millisecond-level power response of the supercapacitor by adjusting the duty cycle of the power switching devices V3 / V4.

[0084] Specifically, when a sudden drop in DC bus voltage is detected, the second converter can instantly switch to Boost mode to raise the supercapacitor voltage to the bus voltage level.

[0085] Example 5

[0086] Example 5 proposes a photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors, as proposed in Example 1, and also puts forward an energy management strategy.

[0087] In this embodiment, specifically, the energy management strategy of the device includes:

[0088] During periods of sufficient sunlight, the Boost converter prioritizes injecting photovoltaic power into the DC bus to supply the load, and the remaining energy is charged to the battery pack through the first converter in a constant current-constant voltage mode.

[0089] When a short-term shadow occurs (such as when clouds pass by), the supercapacitor bank immediately compensates for the photovoltaic power shortfall.

[0090] At night or in the absence of light, the battery pack releases stored energy to the bus in Buck mode through the first converter, while the second converter keeps the supercapacitor in a float charge state in preparation for sudden demand.

[0091] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0092] The background section is provided to generally present the context of this utility model. The work of the currently named inventors, the work to the extent described in this background section, and aspects described in this section that did not constitute prior art at the time of filing are neither expressly nor impliedly acknowledged as prior art to this utility model.

Claims

1. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors, characterized in that, include: Photovoltaic modules, energy storage modules, heat dissipation modules, and junction boxes; The energy storage component includes a battery pack and a supercapacitor pack; the heat dissipation component includes a heat dissipation layer and a heat dissipation fan, the heat dissipation layer being located between the battery pack and the supercapacitor pack, and the heat dissipation fan being located on one side of the heat dissipation layer; the junction box and photovoltaic module are disposed on top of the supercapacitor pack, the photovoltaic module and the energy storage component are connected to the DC bus through the junction box, and the junction box is connected to the microgrid.

2. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 1, characterized in that, The junction box includes a DC bus, a Boost converter, a DC / AC inverter, and two bidirectional Buck-Boost converters connected to the battery pack and the supercapacitor pack, respectively.

3. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 1, characterized in that, The heat dissipation layer has several horizontal heat dissipation holes inside, and the side with the heat dissipation holes is connected to the air inlet of the heat dissipation fan.

4. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 2, characterized in that, The photovoltaic module is connected to the DC bus via a Boost converter; the input of the Boost converter is connected to the photovoltaic module, and the output is connected to the DC bus.

5. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 2, characterized in that, The battery pack is connected to the DC bus via a first bidirectional Buck-Boost converter, and the supercapacitor pack is connected to the DC bus via a second bidirectional Buck-Boost converter.

6. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 2, characterized in that, The DC bus is connected to the microgrid and the cooling fan via a DC / AC inverter. The input terminal of the DC / AC inverter is connected to the DC bus, and the output terminal is connected to the power supply terminals of the microgrid and the cooling fan, respectively.

7. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 5, characterized in that, The main circuit of the first bidirectional Buck-Boost converter includes: a power switching device V1, an inductor L1 and a capacitor C1 connected in series, the battery pack connected in parallel across the capacitor C1, the power switching device V2 connected in parallel between the connection node of the inductor L1 and the capacitor C1, and diodes D1 and D2 connected in reverse parallel across the power switching devices V1 and V2, respectively.

8. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 5, characterized in that, The main circuit of the second bidirectional Buck-Boost converter includes: a power switching device V3, an inductor L2 and a supercapacitor bank connected in series; a power switching device V4 connected in parallel between the connection node of the inductor L2 and the supercapacitor bank; and diodes D3 and D4 connected in reverse parallel across the two ends of the power switching devices V3 and V4, respectively.

9. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 1, characterized in that, The heat dissipation layer, the battery pack, and the supercapacitor pack are all installed in close contact with each other, with the battery pack located on the lower side of the heat dissipation layer and the supercapacitor pack located on the upper side of the heat dissipation layer.

10. A photovoltaic microgrid device based on a hybrid energy storage system of batteries and supercapacitors as described in claim 6, characterized in that, The junction box has a live wire terminal and a neutral wire terminal on its side. The live wire terminal and the neutral wire terminal are connected to the AC output terminal of the DC / AC inverter and the microgrid respectively through wires.

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