Building microgrid system

Abstract

A building microgrid system includes at least two residential energy storage devices and at least two power generation units. Each residential energy storage device is configured to be electrically connected to a power generation unit, a portion of the building's load, and a power grid distribution terminal of the building. Each residential energy storage device includes a battery module, a battery management system, a power conversion unit, and an energy management system. The first AC terminal of the power conversion unit is electrically connected to the portion of the load to provide stable AC power. The second AC terminal of the power conversion unit is electrically connected to the power grid distribution terminal to obtain power from and / or feed power to the external power grid. The DC terminal of the power conversion unit is electrically connected to the power generation unit and the battery module, and the communication terminal of the power conversion unit is electrically connected to the battery management system and the energy management system. This system enables customized design based on electricity demand, improves the flexibility of power generation and energy storage configuration, and enhances the safety and stability of electricity consumption and supply.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a building microgrid system. Background Technology

[0002] A microgrid, also known as a micro-network, is a small-scale power generation and distribution system composed of distributed power sources, energy storage devices, energy conversion devices, loads, and monitoring and protection devices, which can achieve self-control, protection, and management.

[0003] Most current microgrid systems are built using industrial and commercial energy storage equipment, which has the following disadvantages: large size, large space occupation, and poor flexibility in use; the installation locations of photovoltaic modules, energy storage devices, and energy conversion devices are relatively far apart, resulting in complex wiring and high costs; generally, a booster chamber is needed to boost the voltage before grid connection, and then the grid supplies power to the load, which makes the overall architecture of the microgrid system complex and increases losses. Summary of the Invention

[0004] In view of this, the present application provides a building microgrid system to solve at least one problem existing in the background art.

[0005] In a first aspect, one embodiment of this application provides a building microgrid system, including at least two household energy storage devices and at least two power generation units. Each household energy storage device is configured to be electrically connected to a power generation unit, a portion of the building's load, and a power grid distribution terminal of the building. Each household energy storage device includes a battery module, a battery management system, a power conversion unit, and an energy management system.

[0006] The first AC terminal of the power conversion unit is electrically connected to the partial load and is used to provide stable AC power to the partial load; the second AC terminal of the power conversion unit is electrically connected to the power grid distribution terminal and is used to obtain power from the external power grid and / or feed power to the external power grid; the DC terminal of the power conversion unit is electrically connected to the power generation unit and the battery module respectively, and the communication terminal of the power conversion unit is electrically connected to the battery management system and the energy management system respectively.

[0007] In conjunction with the first aspect of this application, in an optional embodiment, the second AC terminal of the power conversion unit of each of the residential energy storage devices is electrically connected to the corresponding grid distribution terminal via a disconnecting switch.

[0008] In conjunction with the first aspect of this application, in an optional embodiment, the partial load is divided by the floors of the building, with each floor equipped with a residential energy storage device, and the load of each floor is electrically connected to the power grid distribution terminal through the residential energy storage device of that floor.

[0009] In conjunction with the first aspect of this application, in an alternative embodiment, the power generation unit includes a photovoltaic unit or a wind power generation unit.

[0010] In conjunction with the first aspect of this application, in an alternative embodiment, the connection between the residential energy storage device and the portion of the load and the power grid distribution terminal is via wiring through the building's electrical shaft.

[0011] In conjunction with the first aspect of this application, in an optional embodiment, the power conversion unit is electrically connected to the partial load via a first switch, and the power conversion unit is electrically connected to the power generation unit via a second switch.

[0012] In conjunction with the first aspect of this application, in an alternative embodiment, the residential energy storage device is arranged adjacent to the power generation unit.

[0013] In conjunction with the first aspect of this application, in an alternative embodiment, the household energy storage devices and power generation units on each floor are all installed on the roof of the building.

[0014] The building microgrid system provided in one embodiment of this application constructs the system using household energy storage devices. These devices are connected between the loads and the power grid, while the grid and loads are not directly connected. This allows for customized design based on actual electricity demand, meeting individualized electricity needs and improving the flexibility of power generation and storage configuration. Furthermore, in the event of a disaster or emergency, the household energy storage devices can quickly switch to islanded operation, ensuring continuous power supply to critical loads and enhancing the reliability and security of power supply. By installing an isolating switch between the second AC terminal of the power conversion unit of each household energy storage device and the corresponding floor's power grid distribution terminal, the power consumption and supply of each load are independently controlled and do not interfere with each other, further improving the safety and stability of power consumption and supply.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 This is a schematic diagram of a building microgrid system according to an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of a residential energy storage device according to an embodiment of this application;

[0019] Figure 3This is a schematic diagram of the installation of a building microgrid system according to an embodiment of this application. Detailed Implementation

[0020] To make the technical solutions and beneficial effects of this application more apparent and understandable, the technical solutions in the embodiments of this application are clearly and completely described below by listing specific examples. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0022] It should be noted that the terms "first," "second," etc., used in this application may be used to describe various elements, but these elements are not limited by these terms. These terms are used only to distinguish one element from another, and not to describe a specific order or sequence. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, not excluding the presence or addition of one or more other features.

[0023] This application provides a building microgrid system, referencing... Figure 1 The system comprises at least two residential energy storage devices 8n and at least two power generation units Pn, where n is a natural number greater than or equal to 1. Each residential energy storage device is electrically connected to a power generation unit Pn, a portion of the building's load Loadn, and a power grid distribution terminal of the building, for receiving electrical energy from the power generation unit and / or the external power grid, and for supplying power to the portion of the building's load and / or feeding power to the external power grid. The power generation unit Pn is used to generate electrical energy and can be a photovoltaic unit, a wind power unit, and / or a diesel generator unit, etc. Residential energy storage devices are energy storage devices for home users, used to store electrical energy and supply power to loads, with an energy capacity typically within 50kWh. Types include split-type, integrated, portable, and balcony energy storage.

[0024] A load is an electrical appliance, and buildings typically contain varying numbers and types of loads. Each household energy storage device is configured to supply power to only a portion of the loads in the building, not to all of them. This "partial load" can be defined by floor (e.g., load on a specific floor) or by building area (e.g., load in a specific building). The grid distribution terminal (gridn) is a branch connection point extending from the grid inlet terminal (Grid). Optionally, the grid distribution terminal is located in the electrical shaft on each floor.

[0025] Figure 1-2 The diagram illustrates a possible connection structure for a building microgrid system, with connections made on a floor-by-floor basis. Some loads are divided by building floors, with one residential energy storage device configured on each floor. The loads on each floor are electrically connected to the grid distribution terminal through their respective residential energy storage devices. The number of generator units Pn and residential energy storage devices 8n is configured according to the actual needs and the number of floors. Optionally, each floor can be configured with one generator unit Pn and one residential energy storage device 8n, or two generator units Pn and one residential energy storage device 8n per floor, or one generator unit Pn and one residential energy storage device 8n for every two floors, and so on.

[0026] Each residential energy storage device includes a battery pack (Batn), a battery management system (BMSn), a power conversion unit (PCSn), and an energy management system (EMSn). The power conversion unit (PCSn) may employ a hybrid converter. It includes a DC-DC converter to convert the DC power generated by the generator into DC power that matches the battery pack (Batn). It also includes a DC-AC bidirectional converter to convert DC power to AC power and vice versa.

[0027] The first AC terminal of the power conversion unit PCSn is electrically connected to a load nF on a specific floor, providing a stable AC power supply to that floor's load. The second AC terminal of the power conversion unit PCSn is electrically connected to the external power grid, used to obtain electrical energy from and / or feed power to the external power grid. A meter is connected between the power conversion unit PCSn and the power grid distribution terminal for electricity monitoring and management. The DC terminals of the power conversion unit PCSn are electrically connected to the generator unit Pn and the battery module Batn, respectively, to receive electrical energy from them. The communication terminals of the power conversion unit PCSn are electrically connected to the battery management system BMSn and the energy management system EMSn, respectively.

[0028] This application embodiment configures residential energy storage devices and power generation units for various load components in a building. Each load component is connected to the power grid via the residential energy storage device, but the loads and the grid are not directly connected. Power is supplied to the loads by the residential energy storage device, reducing dependence on the traditional power grid, thereby lowering electricity costs and increasing energy self-sufficiency. The power generation unit uses renewable energy power generation devices such as photovoltaic or wind power units, improving the utilization rate of green energy and reducing carbon emissions. The residential energy storage device stores electricity generated from clean energy and releases it when needed, improving the stability of clean energy power generation and further enhancing the utilization rate of green energy. Furthermore, this configuration enhances the stability and flexibility of the building's power supply system. When the external power grid fails or the load is too high, the power generation unit and residential energy storage device respond quickly, ensuring the normal operation of critical equipment and improving the stability and security of electricity use.

[0029] The Energy Management System (EMSn) enables the following functions: Energy Dispatch – Customizing charging and discharging plans based on electricity prices, load demand, and photovoltaic power generation forecasts. Multi-Energy Coordination – Managing the complementary operation of multiple energy sources such as photovoltaics, the grid, and batteries. Data Monitoring and Analysis – Real-time monitoring of PCS, BMS, and grid status, analyzing the next steps. Supporting advanced applications such as demand response and virtual power plants. The Power Conversion Unit (PCSn) enables the following functions: Grid-connected / Off-grid Operation – In grid-connected mode, converting DC to AC to feed into the grid or drawing power from the grid to charge batteries; in off-grid mode, providing stable AC power to local loads. Power Regulation – Rapidly adjusting output power based on grid demand, user demand, or EMS commands, such as peak shaving and valley filling, and grid frequency regulation. Power Quality Optimization – Suppressing voltage fluctuations and harmonics to ensure grid stability. Black Start – Independently supplying power to critical loads during grid failures.

[0030] The power conversion unit (PCSn) connects to the energy management system (EMSn) to receive control commands from the EMSn. By constructing a building microgrid system using residential energy storage devices, customized designs can be implemented to meet actual electricity demands, improving the flexibility of power generation and storage configurations. Furthermore, in the event of disasters or emergencies, residential energy storage devices can quickly switch to islanded operation to ensure continuous power supply to critical loads, enhancing the reliability and security of the power supply.

[0031] The second AC terminal of the power conversion unit of each residential energy storage device is electrically connected to the corresponding grid distribution terminal via a disconnecting switch. For example... Figure 1As shown, the household energy storage device 81 on the first floor is electrically connected to the grid distribution terminal grid1 on the first floor via the first disconnecting switch QF1. The household energy storage device 82 on the second floor is electrically connected to the grid distribution terminal grid2 on the first floor via the second disconnecting switch QF2. The household energy storage device 8n on the nth floor is electrically connected to the grid distribution terminal on the nth floor via the nth disconnecting switch QFn. By setting disconnecting switches between the second AC terminal of the power conversion unit PCSn of each energy storage device and the grid distribution terminal of the corresponding floor, the power consumption and supply of each load are independently controlled and do not interfere with each other. When a power generation unit or household energy storage device fails, only the loads connected to that household energy storage device will be affected, and the power consumption of other loads will not be affected. Similarly, when a load fails, such as a short circuit, the power consumption of other loads will not be affected. This further improves the safety and stability of power consumption and supply.

[0032] In each residential energy storage device, a first switch K1n is installed between the load and the power conversion unit PCSn, a second switch K2n is installed between the power generation unit Pn and the power conversion unit PCSn, and a third switch K3n is installed between the battery pack Batn and the power conversion unit PCSn. These switches facilitate the installation and maintenance of each unit and component.

[0033] Figure 2 The internal structure of a residential energy storage device 8n is shown. Each residential energy storage device 8n includes a battery assembly 1, a battery management system 2, a power conversion unit (PCS), and an energy management system (EMS). The PCS and EMS are housed in the same enclosure 3. The battery assembly 1 stores electrical energy and includes multiple cells B1 to Bn. The cells are connected in series to provide a high voltage. The battery management system 2 is connected to the battery assembly 1 and is used to acquire signals and send control signals. The battery assembly 2 includes a master control board (BMU) and multiple slave control boards (BCUn) for signal connection. The number of slave control boards (BCUn) corresponds to the number of cells Bn and is used to acquire cell parameters. The slave control boards (BCUn) are connected sequentially and communicate with each other. Optionally, the master control board (BMU) and the slave control boards (BCUn) are connected and communicate via RS485. The power conversion unit (PCS) is connected to the master control board (BMU) and is used to communicate with the battery management system 2. Optionally, the above connection method uses RS485 or CAN, etc. The power conversion unit PCS is electrically connected to the load via switch K1 and to the grid distribution terminal via disconnect switch QF.

[0034] The Battery Management System (BMS) performs the following functions: Multiple cell protections, such as overcharge / over-discharge protection—detecting individual cell voltages to prevent exceeding safety thresholds and avoid fire or damage; overcurrent protection—limiting charge and discharge current to prevent short circuits or overload operation; temperature management—monitoring battery temperature and ensuring cell temperature remains within normal range through derating or shutdown protection; balancing control—passively balancing the charge of each cell in the battery pack to avoid the "weakest link" effect caused by inconsistencies; state detection and estimation, such as real-time estimation of remaining charge (SOC) and assessment of battery state of health (SOH); performance optimization, such as charge and discharge control—adjusting charge and discharge strategies based on battery status; fault diagnosis—recording abnormal data and triggering alarms or fault-tolerant operation; and data communication and interaction, exchanging data with the PCS (Power Control System) to facilitate the PCS transmitting battery information to the EMS (Electronic Management System), which then coordinates the entire system's operation.

[0035] The main positive line of battery module 1 is connected to the positive input terminal of the power conversion unit PCSn via the first switch K1, fuse FU, and main positive relay KM1. The pre-charge relay KM2 is connected in series with the pre-charge resistor R and then in parallel with the main positive relay KM1 to prevent inrush current caused by voltage surges, thus protecting the circuit. The main negative line of battery module Batn is connected to the negative input terminal of the power conversion unit PCSn via the first switch K1, shunt FL, and main negative relay KM3.

[0036] The power generation unit 4 is illustrated using a photovoltaic power generation unit as an example. It includes multiple photovoltaic panels PVn, all connected to a DC bus BUS. The DC bus BUS is connected to the positive and negative DC input terminals of the power conversion unit PCSn via a second switch K2. The power generation unit 4, together with the battery module 1, battery management system 2, power conversion unit PCS, and energy management system EMS of the residential energy storage device 8n, constitute a power generation and storage device 7.

[0037] like Figure 3 As shown, in one embodiment, the building includes six floors. Each floor includes a load Loadn and a power grid distribution terminal gridn. The first floor includes a load Load1 and a power grid distribution terminal grid1, the second floor includes a load Load2 and a power grid distribution terminal grid2, the third floor includes a load Load3 and a power grid distribution terminal grid3, the fourth floor includes a load Load4 and a power grid distribution terminal grid4, the fifth floor includes a load Load5 and a power grid distribution terminal grid5, and the sixth floor includes a load Load6 and a power grid distribution terminal grid6. The power grid inlet is located on the basement floor of the building. The power grid distribution terminal on each floor is located, for example, in the electrical shaft on each floor. The power grid distribution terminal on each floor is connected to the power grid inlet via a cable tray. Therefore, the electricity for each floor comes from the same power grid inlet.

[0038] Each floor is equipped with one power generation and energy storage unit 71-76, with the photovoltaic unit PVn and the residential energy storage unit 8n placed adjacent to each other, for example, both on the roof, making wiring and maintenance more convenient. Each floor is equipped with one residential energy storage unit 8n. The two AC output terminals of the power conversion unit PCS of each power generation and energy storage unit have two lines leading out to the corresponding floor's load Loadn and the grid distribution terminal gridn, respectively. For example... Figure 3 As shown, the two AC output terminals of the power conversion unit PCS of the energy storage device 71 on the first floor are connected to the load Load1 and the power grid distribution terminal grid1 on that floor via two lines 51 and 61 respectively. The power conversion unit PCSn of each household energy storage device 8n is wired to the load and power grid distribution terminal on the corresponding floor through the cable trays in the building. By using the existing wiring channels in the building, the wiring difficulty is reduced and the cost is saved. The household energy storage devices 8n configured on each floor are independently controlled and come from the same inbound power grid.

[0039] The photovoltaic modules in this embodiment can be oversupplied, ensuring sufficient capacity to simultaneously power the load and charge the battery under good sunlight conditions. Under moderate sunlight conditions, priority is given to powering the load. When photovoltaic power generation is insufficient for the load, the battery, along with the photovoltaic modules, will power the load. In grid-connected scenarios, if the combined power from the photovoltaic modules and the battery is insufficient to support the load, electricity will be purchased from the grid to power the load. Actual usage verification shows that under good sunlight conditions, the entire building can save over 300 kWh of electricity per day.

[0040] The residential energy storage device of this application includes a battery module Bn, which acts as an independent power source to supply power to the load and meet electricity demand in the event of a grid failure. In the off-grid situation, if the combined photovoltaic power generation and battery power are insufficient to support the load, an overload fault may occur. In this case, the residential energy storage device stops supplying power to the load, reducing the number of electrical devices used, so that the system can continue to operate normally.

[0041] The residential energy storage device of this application includes an energy management system (EMSn) with comprehensive detection and protection mechanisms. It can detect the leakage current of building electrical equipment and will alarm or even shut down when the value exceeds a certain value, thereby improving the safety and reliability of the entire building's power supply.

[0042] In the above embodiments, n is a natural number greater than or equal to 1.

[0043] In addition to applications in buildings, the microgrid system of this application can also be applied to high-energy-consuming industrial parks, mining areas and oil fields, remote rural areas, mountainous areas, zero-carbon communities, emergency and disaster prevention situations, etc.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A building microgrid system, characterized in that, It includes at least two residential energy storage devices and at least two power generation units, each of the residential energy storage devices being configured to be electrically connected to a power generation unit, a portion of the building's load, and a power grid distribution terminal of the building; each of the residential energy storage devices includes a battery module, a battery management system, a power conversion unit, and an energy management system; The first AC terminal of the power conversion unit is electrically connected to the partial load and is used to provide stable AC power to the partial load; the second AC terminal of the power conversion unit is electrically connected to the power grid distribution terminal and is used to obtain power from the external power grid and / or feed power to the external power grid; the DC terminal of the power conversion unit is electrically connected to the power generation unit and the battery module respectively, and the communication terminal of the power conversion unit is electrically connected to the battery management system and the energy management system respectively.

2. The building microgrid system according to claim 1, characterized in that, The second AC terminal of the power conversion unit of each of the residential energy storage devices is electrically connected to the corresponding power grid distribution terminal via an isolating switch.

3. The building microgrid system according to claim 1, characterized in that, The load is divided by the floors of the building, with each floor equipped with a household energy storage device. The load of each floor is connected to the power grid distribution terminal through the household energy storage device of that floor.

4. The building microgrid system according to claim 1, characterized in that, The power generation unit includes a photovoltaic unit or a wind power generation unit.

5. The building microgrid system according to claim 1, characterized in that, The power conversion unit is electrically connected to the partial load via a first switch, and the power conversion unit is electrically connected to the power generation unit via a second switch.

6. The building microgrid system according to claim 1, characterized in that, The household energy storage device is arranged adjacent to the power generation unit.

7. The building microgrid system according to claim 6, characterized in that, The household energy storage devices and power generation units on each floor are all installed on the roof of the building.

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