Multi-bus-level direct-current micro-grid system for park optical storage system

Abstract

The utility model discloses a multi-bus-level direct-current micro-grid system for a park optical storage system. The system comprises a park-level direct-current bus, a building-level direct-current bus, a household low-voltage direct-current bus, a photovoltaic power generation system, an energy storage system and an energy management system. Wherein the park-level direct-current bus is connected with commercial power through an AC / DC converter, and is also connected with the building-level direct-current bus through a building DC / DC converter; the building-level direct-current bus is also connected with the household low-voltage direct-current bus through the household DC / DC converter, and a plurality of pieces of direct-current load equipment are connected to the corresponding direct-current bus; the photovoltaic power generation system and the energy storage system are respectively connected with the park-level DC bus, and the photovoltaic power generation system and the energy storage system are also connected with the energy management system. According to the system, loads of different voltage grades can be conveniently accessed to the power grid by adopting the multi-stage bus, energy scheduling is performed by utilizing the energy management system, the structure of the micro-grid is optimized, and safe and stable operation of the micro-grid is ensured.

Description

Technical Field

[0001] This utility model relates to the field of DC microgrid technology, and in particular to a multi-bus DC microgrid system for a park photovoltaic-storage system. Background Technology

[0002] With the increasing demand for electricity and the growing awareness of environmental protection, energy transition has become a mainstream trend. Against the backdrop of rapid industrial and technological development, many clean energy sources are emerging, accelerating the substitution of electricity for energy consumption. New power systems employing renewable energy technologies are characterized by cleanliness and low carbon emissions, and can flexibly aggregate resources and allocate them efficiently.

[0003] Among them, DC microgrids, which are based on the rise of clean energy, have become an important way to efficiently develop clean energy and reduce environmental pollution. DC microgrids are microgrids composed of DC power, which can efficiently accommodate distributed renewable energy generation systems such as wind power and solar power, as well as DC power loads.

[0004] However, due to the unstable nature of clean energy power generation influenced by natural conditions and limitations in the DC microgrid architecture, DC microgrids in related technologies may experience "wind and solar curtailment," leading to low energy utilization. Furthermore, in practical applications, microgrids need to connect to different electrical loads within the industrial park, and these loads have different rated voltage levels. Therefore, related technologies require connecting a large number of converters, inverters, and rectifiers to the DC microgrid system, resulting in a large number of devices and a complex connection structure, increasing the failure rate. Utility Model Content

[0005] The purpose of this utility model is to at least partially solve one of the aforementioned technical problems.

[0006] Therefore, the purpose of this invention is to propose a multi-bus DC microgrid system for a photovoltaic-storage system in a park. This system utilizes an energy management system to better integrate clean energy generation into the DC microgrid system, and classifies the buses to facilitate the connection of loads at different voltage levels, providing safe and stable power to the park.

[0007] To achieve the above objectives, this utility model proposes a multi-bus DC microgrid system for a park-level photovoltaic-storage system. The system includes: a park-level DC bus, a building-level DC bus, a residential low-voltage DC bus, a photovoltaic power generation system, an energy storage system, and an energy management system; wherein,

[0008] The campus-level DC bus is connected to the external mains power through an AC / DC converter, and the campus-level DC bus is also connected to the building-level DC bus through a building DC / DC converter.

[0009] The building-level DC bus is also connected to the residential low-voltage DC bus via a residential DC / DC converter. Multiple building DC load devices are connected to the building-level DC bus, and multiple residential DC load devices are connected to the residential low-voltage DC bus.

[0010] The photovoltaic power generation system and the energy storage system are respectively connected to the park-level DC bus through different DC / DC converters. The photovoltaic power generation system and the energy storage system are also connected to the energy management system.

[0011] The energy management system is used to perform power dispatching on load systems of different voltage levels connected in a multi-bus DC microgrid, and works in conjunction with the energy storage system to absorb photovoltaic power generation.

[0012] In addition, the multi-bus DC microgrid system for park photovoltaic-storage systems according to this utility model embodiment also has the following additional technical features:

[0013] Optionally, in some embodiments, the multi-bus DC microgrid system further includes a protection system, which includes: a host unit mounted on a microgrid protection and control management platform; and multiple field protection devices distributed at different equipment locations in the park, with the host unit connected to each field protection device via an RS-485 hub.

[0014] Optionally, in some embodiments, the plurality of field protection devices include: a grid-connected circuit breaker, the first terminal of which is connected to the external mains power, the second terminal of which is connected to the AC / DC converter, and the grid-connected circuit breaker is used to switch the grid-connected and grid-connected states of the multi-bus DC microgrid.

[0015] Optionally, in some embodiments, when the grid-connected / off-grid circuit breaker is disconnected, the multi-bus DC microgrid switches from a grid-connected state to an off-grid state; when the grid-connected / off-grid circuit breaker is closed, the multi-bus DC microgrid switches from an off-grid state to a grid-connected state.

[0016] Optionally, in some embodiments, the plurality of field protection devices further include: a grid-connected monitoring and control protection device, the first end of which is connected to the AC / DC converter, and the second end of which is connected to the park-level DC bus; and a plurality of equipment protection devices, the plurality of equipment protection devices including circuit breakers correspondingly connected between different equipment and each level of DC bus.

[0017] Optionally, in some embodiments, the energy management system is also connected to the DC loads in the microgrid and the distribution network. Specifically, the energy management system is used to: predict the power load data and photovoltaic output data for future periods based on historical data, and formulate a power dispatch plan based on the predicted data.

[0018] Optionally, in some embodiments, the microgrid protection and control management platform further includes: a microgrid central controller, wherein the energy management system is connected to the microgrid central controller via Ethernet, and the microgrid central controller is also connected to multiple system devices via an RS-485 hub; the microgrid central controller is used to manage the operation mode of the multi-bus DC microgrid.

[0019] Optionally, in some embodiments, the energy management system includes: a power prediction module, a data storage module, an economic dispatch module, a status detection module, a statistical report module, and a data publishing module; the microgrid central controller includes: a data acquisition module, a relay protection module, a mode switching module, a communication interface, and a human-machine interaction module.

[0020] Optionally, in some embodiments, the multi-bus DC microgrid system further includes: a fast charging pile, which is connected to the park-level DC bus, and the park-level DC bus is used to provide power to the fast charging pile.

[0021] Optionally, in some embodiments, the photovoltaic power generation system includes a photovoltaic array installed at various building locations within the park.

[0022] The technical solution provided by the embodiments of this utility model brings at least the following beneficial effects: This utility model adopts a multi-level bus architecture to facilitate the connection of loads of different voltage levels. During power generation, distribution, and consumption, there is no need to install additional inverter and rectifier equipment. This not only reduces power losses from photovoltaic and energy storage systems connected to the grid, as well as power losses from DC load connections, but also optimizes the structure of the park's DC microgrid. By reducing the number of connecting devices, the complexity of equipment connections in the grid is reduced, further improving the reliability of power supply within the park. Furthermore, by installing photovoltaic arrays in the park's buildings, the photovoltaic power generation system and energy storage system are integrated with the park's DC microgrid. The energy storage system controls its output according to the peak-shaving and valley-filling curve, charging during off-peak hours and discharging during peak hours, better absorbing photovoltaic power to achieve peak-shaving and valley-filling, thus reducing the park's electricity costs. In addition, an energy management platform is built in the microgrid system to perform power dispatching for each load system, maximizing energy utilization and further reducing the park's electricity costs.

[0023] Additional aspects and advantages of this invention 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 the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0025] Figure 1 This is a schematic diagram of the structure of a multi-bus DC microgrid system for a park photovoltaic-storage system proposed in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram illustrating the connection relationship and working principle of an energy management system proposed in an embodiment of this utility model;

[0027] Figure 3 This is a schematic diagram illustrating the connection method of various modules in a DC microgrid for energy management and scheduling, as proposed in an embodiment of this utility model.

[0028] The reference numerals in the attached figures represent:

[0029] 10-Park-level DC bus, 20-Building-level DC bus, 30-Residential low-voltage DC bus, 40-Photovoltaic power generation system, 50-Energy storage system, 60-Energy management system, 70-Microgrid protection and control management platform, 80-AC / DC converter, 90-Building DC / DC converter, 100-Residential DC / DC converter, 110-Fast charging pile, 120-Photovoltaic DC / DC converter, 130-Energy storage DC / DC converter. Detailed Implementation

[0030] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0031] The following description, with reference to the accompanying drawings, describes a multi-bus DC microgrid system for a park photovoltaic-storage system, according to an embodiment of the present invention.

[0032] Figure 1 This is a schematic diagram of the structure of a multi-bus DC microgrid system for a park photovoltaic-storage system, as proposed in an embodiment of this utility model. Figure 1 As shown, the system includes: a park-level DC bus 10, a building-level DC bus 20, a household low-voltage DC bus 30, a photovoltaic power generation system 40, an energy storage system 50, and an energy management system 60.

[0033] Among them, the park-level DC bus 10 is connected to the external mains power through the AC / DC converter 80, and the park-level DC bus 10 is also connected to the building-level DC bus 20 through the building DC / DC converter 90.

[0034] Specifically, the voltage of the external mains power connected to the park-level DC bus 10 is determined based on the actual conditions of the DC microgrid system. For example, Figure 1 The example used is 10kV mains power.

[0035] The building-level DC bus 20 is also connected to the residential low-voltage DC bus 30 via the residential DC / DC converter 100. Multiple building DC load devices are connected to the building-level DC bus 20, and multiple residential DC load devices are connected to the residential low-voltage DC bus 30.

[0036] The photovoltaic power generation system 40 and the energy storage system 50 are connected to the park-level DC bus 10 through different DC / DC converters, for example, Figure 1 The photovoltaic power generation system 40 is connected to the park-level DC bus 10 via a photovoltaic DC / DC converter 120, and the energy storage system 50 is connected to the park-level DC bus 10 via an energy storage DC / DC converter 130. The photovoltaic power generation system 40 and the energy storage system 50 are also connected to the energy management system 60.

[0037] The energy management system 60 is used to perform power dispatching on load systems of different voltage levels connected in a multi-bus DC microgrid, and to work in conjunction with the energy storage system 50 to absorb photovoltaic power generation.

[0038] Specifically, the DC microgrid system of this invention is internally divided into three levels of busbars. The specific configuration of different busbar levels is based on indicators such as distribution capacity, power supply distance, line loss and voltage deviation, and power safety. Simultaneously, the converter characteristics, operational stability, and efficiency of the core converter equipment of the DC distribution network must also be considered. Each busbar level can connect to loads of different voltage levels, for example... Figure 1 As shown, it includes a park-level DC bus (750V), a building-level DC bus (375V), and a household low-voltage DC bus (48V). The voltage level of each bus connected to the load can be adjusted according to actual needs, and this utility model does not limit this.

[0039] The campus-level DC bus 10 can connect the photovoltaic power generation system 40 and the energy storage system 50. The building-level DC bus 20 is connected to the campus-level DC bus 10 via a DC / DC converter, and can supply power to multiple building DC load devices such as air conditioners, water heaters, and microwave ovens. The residential low-voltage DC bus 30 is connected to the building-level DC bus 20 via a DC / DC converter, and can supply power to multiple residential DC load devices such as computers, printers, and lighting fixtures.

[0040] In one embodiment of this invention, the photovoltaic power generation system 40 includes multiple photovoltaic arrays, each installed at a different building location within the park. Thus, this invention integrates photovoltaic power generation with the park's DC microgrid and connects it to the park-level DC bus 10 to provide power to the park.

[0041] In one embodiment of this invention, the system further includes a fast charging pile 110, which is connected to a park-level DC bus 10. The park-level DC bus 10 provides power to the fast charging pile 110. In this embodiment, the fast charging pile can charge electric vehicles. Therefore, in the DC microgrid system of this invention, power can be provided to fast charging piles for electric vehicles within the park through the park-level DC bus 10.

[0042] Therefore, the multi-bus DC microgrid system of this utility model adopts a multi-level DC bus to facilitate the connection of loads of different voltage levels. Thus, in the process of power generation, distribution and consumption in the power grid, there is no need for inverter and rectification links. This not only reduces the power loss into the grid, but also reduces the equipment used in the DC microgrid system, optimizes the system structure and improves the reliability of power supply in the park.

[0043] As one possible implementation, when specifically implementing this multi-bus DC microgrid system, a DC 750V / DC 375V / DC 48V DC power distribution voltage level sequence can be established with a multi-port energy router as the core of the DC microgrid system. Specifically, the multi-port energy router has an AC port capacity of 100kW, six DC ports, a photovoltaic interface connecting to a 30kWp rooftop photovoltaic system, energy storage interface 1 configured with a 50kW / 60kWh lithium iron phosphate battery, energy storage interface 2 configured with a 10kW / 40kWh lead-carbon battery, a DC 375V interface connecting to a 4.462kW lobby load, and a 60kW DC-DC charging pile connected to the DC 750V side.

[0044] In one embodiment of this utility model, the multi-bus DC microgrid system further includes a protection system, which includes: a host, which is mounted on the microgrid protection and control management platform 70; and multiple field protection devices, which are distributed at different equipment locations in the park. The host is connected to the different field protection devices through an RS-485 hub.

[0045] Specifically, in this embodiment, the protection system of the DC microgrid can adopt a Modbus bus structure, using two industrial control computers as the host, with redundancy between the two computers. The host computers use shielded twisted-pair cables and are connected to various protection devices distributed in different locations in the park via RS-485 optical isolation hubs. The host equipment located in the master station layer has bus access rights, can send commands to poll the various field protection devices in the substation layer, and wait for responses from each device.

[0046] The protection function of the protection system in this embodiment mainly consists of the instantaneous overcurrent protection of the off-grid circuit breaker QF1, the grid-connected protection of the grid-connected measurement and control protection device KM1, and the equipment protection devices corresponding to each device in the DC microgrid system.

[0047] Specifically, in the utility model embodiment, multiple field protection devices include: a grid-connected circuit breaker QF1, such as... Figure 1 As shown, the first terminal of the off-grid circuit breaker QF1 is connected to the external mains power, and the second terminal of the off-grid circuit breaker QF1 is connected to the AC / DC converter 80. The off-grid circuit breaker is used to switch the on-grid and off-grid status of the multi-bus DC microgrid.

[0048] For example, when the grid connection / off-grid circuit breaker is disconnected, the multi-bus DC microgrid switches from grid-connected to off-grid mode; when the grid connection / off-grid circuit breaker is closed, the multi-bus DC microgrid switches from off-grid to grid-connected mode. Specifically, the DC microgrid system can perform grid connection / off-grid operations. When a fault occurs in the external power grid, the DC microgrid switches from grid-connected to off-grid mode simply by disconnecting the QF1 circuit breaker, and the energy storage converter within the microgrid switches its operating mode. When the microgrid switches from off-grid to grid-connected mode, only the QF1 circuit breaker needs to be closed, and the DC microgrid connects to the external power grid, allowing the load to be powered. Other power supply equipment performs self-tests simultaneously, achieving stable grid-connected operation.

[0049] In one embodiment of this utility model, the multiple field protection devices further include: a grid-connected monitoring and control protection device KM1, the first end of which is connected to the AC / DC converter 80, and the second end of which is connected to the park-level DC bus 10; and multiple equipment protection devices, each of which includes a circuit breaker correspondingly connected between different equipment and each level of DC bus.

[0050] Specifically, in this embodiment, the protection strategy of the QF1 circuit breaker is implemented in the microgrid control system, and the grid connection protection strategy is implemented by installing a microgrid grid connection protection and control device at the KM1 terminal. For example, when switching to the grid connection state, after determining that each power supply device has completed its self-test and that the DC microgrid system has the conditions for grid connection and can achieve safe grid connection, KM1 is closed to perform the grid connection operation.

[0051] In a microgrid system, the protection of each device is achieved locally by its corresponding device protection device. For example, multiple device protection devices can be as follows: Figure 1 The circuit breakers shown are QF2 through QF16, as follows: Figure 1 As shown, each system connected to the microgrid, DC load equipment, and various devices such as DC / DC converters correspond to a circuit breaker. Each circuit breaker is connected between the corresponding protected device and the corresponding DC bus. For example, QF2, connected between the park-level DC bus 10 and the photovoltaic DC / DC converter 120, can protect the photovoltaic DC / DC converter 120. Alternatively, it can be connected between the protected device and other devices. For example, QF3, connected between the photovoltaic power generation system 40 and the photovoltaic DC / DC converter 120, can protect the photovoltaic power generation system 40. In addition to self-checking and synchronization functions, QF3 and KM1 primarily protect the park-level DC bus 10 and the building-level DC bus 20.

[0052] Therefore, this utility model ensures the safe and stable operation of the DC microgrid system by setting up a protection system.

[0053] As described above, this utility model also integrates the photovoltaic power generation system 40 and the energy storage system 50 into the DC microgrid, and completes the energy dispatch of each load system by setting up the energy management system 60. Combined with the energy storage system 50, photovoltaic absorption is carried out to achieve peak shaving and valley filling, which is conducive to maximizing the utilization of electricity.

[0054] In one embodiment of this utility model, such as Figure 2 As shown, the energy management system 60 is also connected to the DC loads and distribution network in the microgrid. Specifically, the energy management system is used to: predict the power load data and photovoltaic output data for future periods based on historical data, and formulate power dispatch plans based on the predicted data.

[0055] Specifically, the energy management system 60 of this utility model can realize functions such as prediction and optimization control. The microgrid energy management system 60 first uses a wavelet neural network prediction algorithm to analyze the collected data (including...) Figure 2The photovoltaic and load data shown in the figure are preprocessed. Based on the historical data of the previous day, the various parameters of the system are comprehensively predicted to obtain the power load plan data and photovoltaic output prediction data for the future period, so as to prepare for the early formulation of scheduling plans.

[0056] In one embodiment of this utility model, the microgrid protection and control management platform 70 further includes: a microgrid central controller; the energy management system 60 is connected to the microgrid central controller via Ethernet; the microgrid central controller is also connected to multiple system devices via an RS-485 hub; the microgrid central controller is used to manage the operation mode of the multi-bus DC microgrid.

[0057] Specifically, in this embodiment, as Figure 3 As shown, the DC microgrid system realizes data acquisition and energy dispatch. It adopts the concept of centralized management and hierarchical control to perform hierarchical / graded control of the equipment in the entire system, solves the coordinated control of distributed photovoltaic, energy storage and load, ensures the autonomous power balance within the microgrid, and maximizes the utilization of electricity.

[0058] The energy management system includes: a power prediction module, a data storage module, an economic dispatch module, a status monitoring module, a statistical reporting module, and a data publishing module. The microgrid central controller includes: a data acquisition module, a relay protection module, a mode switching module, a communication interface, and a human-machine interface module.

[0059] The energy management system, microgrid central controller, and system equipment include various modules and their functions, such as... Figure 3 As shown, the names of each module correspond to its functions, which will not be elaborated here.

[0060] It should be noted that after integrating photovoltaic power generation and energy storage with the park's DC microgrid, the energy storage system 50 can control its output according to the peak shaving and valley filling curve, charging during off-peak hours and discharging during peak hours, thus better absorbing photovoltaic power to achieve peak shaving and valley filling and reducing the park's electricity costs.

[0061] Specifically, by configuring energy storage, all photovoltaic power generation can be consumed locally. The energy storage system 50 controls its output according to the peak shaving and valley filling curve, charging during off-peak hours and discharging during peak hours. Based on this strategy, the photovoltaic MPPT in the system behaves as follows under normal operating conditions: the energy storage system charges at night and discharges during the day; the photovoltaic system's MPPT generates power normally during the day. When the external power grid fails, the DC microgrid system operates off-grid, with the photovoltaic power generation system 40 and the energy storage system 50 supporting the park-level DC bus to maintain the stable operation of the DC microgrid.

[0062] Therefore, the multi-bus DC microgrid system of this utility model combines a photovoltaic power generation system and an energy storage system and performs energy dispatch to supply power to the park. The photovoltaic power generation system is connected to the park's DC microgrid, and the energy management system is used for power dispatch, giving full play to the advantages of clean energy power generation and promoting the construction of a green park.

[0063] In summary, the multi-bus DC microgrid system for a solar-energy storage system in a park, as described in this embodiment, adopts a multi-bus architecture to facilitate the connection of loads at different voltage levels. During power generation, distribution, and consumption, no additional inverter or rectifier equipment is required. This not only reduces power losses from solar and energy storage systems entering the grid, as well as power losses from DC load connections, but also optimizes the structure of the park's DC microgrid. By reducing the number of connecting devices, the complexity of equipment connections in the grid is lowered, further improving the reliability of power supply within the park. Furthermore, the system integrates solar power generation and energy storage systems with the park's DC microgrid by installing solar arrays in the park's buildings. The energy storage system controls its output according to peak-shaving and valley-filling curves, charging during off-peak hours and discharging during peak hours, better absorbing solar power to achieve peak-shaving and valley-filling, thus reducing the park's electricity costs. Additionally, an energy management platform is built within the microgrid system to perform power dispatching for each load system, maximizing energy utilization and further reducing the park's electricity costs.

[0064] It should be noted that in the description of this utility model, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0065] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the present invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of the present invention pertain.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A multi-bus DC microgrid system for a solar-energy storage system in a park, characterized in that, include: Park-level DC busbars, building-level DC busbars, residential low-voltage DC busbars, photovoltaic power generation systems, energy storage systems, and energy management systems; among them... The campus-level DC bus is connected to the external mains power through an AC / DC converter, and the campus-level DC bus is also connected to the building-level DC bus through a building DC / DC converter. The building-level DC bus is also connected to the residential low-voltage DC bus via a residential DC / DC converter. Multiple building DC load devices are connected to the building-level DC bus, and multiple residential DC load devices are connected to the residential low-voltage DC bus. The photovoltaic power generation system and the energy storage system are respectively connected to the park-level DC bus through different DC / DC converters. The photovoltaic power generation system and the energy storage system are also connected to the energy management system. The energy management system is used to perform power dispatching on load systems of different voltage levels connected in a multi-bus DC microgrid, and works in conjunction with the energy storage system to absorb photovoltaic power generation.

2. The multi-bus DC microgrid system according to claim 1, characterized in that, It also includes a protection system, which includes: The host is mounted on the microgrid protection and control management platform; Multiple field protection devices are distributed at different equipment locations in the park, and the host is connected to each field protection device via an RS-485 hub.

3. The multi-bus DC microgrid system according to claim 2, characterized in that, The plurality of field protection devices include: The circuit breaker is used to switch the grid connection and disconnection status of a multi-bus DC microgrid. Its first terminal is connected to the external mains power, and its second terminal is connected to the AC / DC converter.

4. The multi-bus DC microgrid system according to claim 3, characterized in that, When the grid-connected / off-grid circuit breaker is disconnected, the multi-bus DC microgrid switches from grid-connected to off-grid state; when the grid-connected / off-grid circuit breaker is closed, the multi-bus DC microgrid switches from off-grid to grid-connected state.

5. The multi-bus DC microgrid system according to claim 2, characterized in that, The plurality of field protection devices also include: A grid-connected monitoring and control protection device, wherein the first end of the grid-connected monitoring and control protection device is connected to the AC / DC converter, and the second end of the grid-connected monitoring and control protection device is connected to the park-level DC bus; Multiple equipment protection devices, including circuit breakers correspondingly connected between different equipment and DC buses at various levels.

6. The multi-bus DC microgrid system according to claim 1, characterized in that, The energy management system is also connected to the DC loads in the microgrid and the distribution network. Specifically, the energy management system is used to: predict the power load data and photovoltaic output data for future periods based on historical data, and formulate power dispatch plans based on the predicted data.

7. The multi-bus DC microgrid system according to claim 2, characterized in that, The microgrid protection and control management platform also includes: The energy management system is connected to the microgrid central controller via Ethernet, and the microgrid central controller is also connected to multiple system devices via an RS-485 hub; The microgrid central controller is used to manage the operation mode of the multi-bus DC microgrid.

8. The multi-bus DC microgrid system according to claim 7, characterized in that, The energy management system includes: a power prediction module, a data storage module, an economic dispatch module, a status detection module, a statistical report module, and a data publishing module; The microgrid central controller includes: a data acquisition module, a relay protection module, a mode switching module, a communication interface, and a human-machine interaction module.

9. The multi-bus DC microgrid system according to claim 1, characterized in that, Also includes: A fast charging pile is provided, which is connected to the park-level DC bus, which is used to provide power to the fast charging pile.

10. The multi-bus DC microgrid system according to claim 1, characterized in that, The photovoltaic power generation system includes a photovoltaic array, which is installed at various building locations within the park.

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