Three-bus AC / DC micro-grid architecture

Abstract

The invention discloses a three-bus AC / DC micro-grid architecture, which comprises a low-energy-carrying DC bus, and a small-power photovoltaic power generation unit, a small-power wind power generation unit, a small-power fuel cell unit and a small-capacity energy storage unit which are connected, and is characterized in that the nominal voltages of the low-energy-carrying DC bus are 12V, 24V and 48V, and the low-energy-carrying DC bus is used for supplying power to a low-voltage DC load; the high-power photovoltaic power generation unit, the high-power wind power generation unit, the high-power fuel cell unit and the high-capacity energy storage battery are connected, the nominal voltage of the high-energy-carrying direct-current bus is 375V, 400V, 600V, 750V and 900V, and the high-energy-carrying direct-current bus is used for supplying power to a high-power direct-current load; the system comprises an alternating current bus, an accessed mains supply, an internal combustion generator set and an energy storage converter, the voltage of the alternating current bus is 220 / 380V, the frequency of the alternating current bus is 50Hz, and the alternating current bus is used for supplying power to an alternating current load; the low-energy-carrying direct-current bus and the 220V alternating-current bus form a low-power micro-grid, the high-energy-carrying direct-current bus and the 380V alternating-current bus form a high-power micro-grid, and the low-power micro-grid and the high-power micro-grid are connected in parallel through the 380V alternating-current bus to form a three-bus micro-grid framework of the low-energy-carrying direct-current bus, the high-energy-carrying direct-current bus and the alternating-current bus. According to the invention, the power supply guarantee flexibility in emergency rescue, field operation and other scenes is improved.

Description

Technical Field

[0001] The present invention relates to a distributed microgrid technology, and in particular to a three-bus AC / DC microgrid architecture. Background Art

[0002] In view of the disadvantage of large-scale power outages caused by natural disasters and wars, and the rapid development of new energy technologies such as wind power generation, photovoltaic power generation, energy storage batteries, fuel cells, etc. in recent years, the use of new energy technologies such as wind power generation, photovoltaic power generation, energy storage batteries, fuel cells, etc. in combination with traditional internal combustion engine power generation to build distributed microgrids for local power supply has received increasing attention. There is a strong application demand in scenarios such as data centers, hospitals, banks, military facilities, etc. that have high requirements for power supply reliability, remote areas without power grid coverage, and emergency rescue in the event of large power grid failures.

[0003] In scenarios such as emergency rescue and field operations, microgrid products need to meet the following requirements: 1) To meet the needs of different rescue or combat missions, they can quickly build microgrids of different power levels and scales based on as few product models as possible; 2) Multiple microgrids can be connected to form microgrid groups to achieve interconnection; 3) They can adapt to as many different power loads as possible. However, the existing microgrid architectures cannot meet the above requirements, so a new microgrid architecture needs to be innovatively built.

[0004] At present, there are two types of microgrid products built for emergency rescue and field combat power supply needs. The first type is a small DC photovoltaic storage microgrid, with a power of several hundred watts to several kilowatts, which is used for emergency lighting, communications, etc. The second type is a medium-to-high power AC microgrid, with a power of tens of kilowatts to hundreds of kilowatts, which is used to power emergency rescue camps, hospitals and large equipment. Currently, both types of products are isolated microgrids, and multiple sets cannot be interconnected and networked to support each other, and power expansion cannot be achieved to support a wider range of power supply needs. There are often problems such as "big horses pulling small carts" and "small horses can't pull big carts". Summary of the invention

[0005] The purpose of the present invention is to provide a three-bus AC / DC microgrid architecture.

[0006] The technical solution to achieve the purpose of the present invention is: a three-bus AC / DC microgrid architecture, comprising: Low-load DC bus, and connected small-power photovoltaic power generation units, small-power wind power generation units, small-power fuel cell units and small-capacity energy storage units. The nominal voltage of the low-load DC bus is 12V, 24V, and 48V, which is used to supply power to low-voltage DC loads; High-energy-load DC bus, as well as connected high-power photovoltaic power generation units, high-power wind power generation units, high-power fuel cell units and large-capacity energy storage batteries. The nominal voltage of the high-energy-load DC bus is 375V, 400V, 600V, 750V, and 900V, which is used to supply power to high-power DC loads; AC busbar, as well as connected mains, internal combustion generator sets and energy storage converters. The voltage of the AC busbar is 220 / 380V and the frequency is 50Hz, which is used to supply power to AC loads. The low-load DC bus and 220V AC bus form a small-power microgrid, the high-load DC bus and 380V AC bus form a high-power microgrid, and the small-power microgrid and the high-power microgrid are connected in parallel through the 380V AC bus to form a three-bus microgrid architecture of "low-load DC bus + high-load DC bus + AC bus".

[0007] Furthermore, the small-power microgrid is an AC / DC hybrid microgrid architecture, and multiple small-power microgrids are connected in parallel on the low-voltage DC bus or 220V AC bus side to expand the low-voltage DC or 220V AC power supply capacity.

[0008] Furthermore, 3 sets and integer multiples of 3 sets of small-power microgrids are operated in staggered phases with a phase difference of 120°, that is, a 380V AC bus is constructed to supply power to 380V AC loads.

[0009] Furthermore, the high-power microgrid is an AC / DC hybrid microgrid architecture, and multiple high-power microgrids are connected in parallel on the high-load DC bus or 380V AC bus side to expand the high-voltage DC or 380V AC power supply capacity.

[0010] Furthermore, when the power supply capacity of the small-power microgrid is insufficient, the large-power microgrid provides support power supply to the small-power microgrid; When a high-power microgrid fails or has insufficient energy, multiple small-power microgrids provide emergency support and power to the high-power microgrid.

[0011] Furthermore, the microgrid supports plug-and-play, and multiple sets of small-power microgrids and high-power microgrids form a microgrid group, which can be used in combination or split into multiple microgrids for independent use.

[0012] Compared with the prior art, the present invention has the following significant advantages: 1) The three-bus microgrid architecture is adopted, which can take into account the access of microgrid products of different power levels and capacities, and construct small-power microgrids, high-power microgrids and interconnected microgrid groups to adapt to application scenarios with different power requirements; 2) In the microgrid group constructed based on the three-bus microgrid architecture, the power between each microgrid is interconnected and can support each other to provide highly reliable power supply for various loads; 3) In the microgrid group constructed based on the three-bus microgrid architecture, each microgrid can be quickly split and the power supply can be temporarily used outside, thereby improving the application flexibility of the microgrid; 4) 3 or more sets of small-power microgrids can operate in staggered phases, so that 380V AC can be output through combination, so that small-power microgrid products can supply power to high-power loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is an architecture diagram of a microgrid group with a three-bus microgrid architecture according to the present invention.

[0014] Figure 2 This is an architecture diagram of a low-power microgrid according to the present invention.

[0015] Figure 3 It is an architecture diagram of a high-power microgrid of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0017] Definitions of Abbreviations and Key Terms 1. Microgrid: In this article, microgrid refers to a distributed small power grid constructed by multiple energy sources such as wind power generation, photovoltaic power generation, internal combustion engine power generation, energy storage batteries, fuel cells, etc., including grid-connected microgrids and off-grid microgrids.

[0018] 2. Busbar: The busbar in this article refers to the public connection line in the microgrid that is used to connect multiple electrical lines and collect, distribute and transmit electrical energy.

[0019] The present invention discloses a three-bus AC / DC microgrid architecture, which adopts a three-bus microgrid architecture of "low-load DC bus + high-load DC bus + AC bus". The architecture takes into account the access of small-power microgrids and high-power microgrids, supports the rapid interconnection and networking of multiple microgrids at the same or different levels to build a microgrid group, and the rapid splitting and use of microgrid groups, so that suitable microgrids can be quickly built according to the requirements of emergency rescue, field operations and other tasks, and supports various power loads.

[0020] In the three-bus AC / DC microgrid architecture, there is a low-load DC bus, a high-load DC bus and an AC bus. The nominal voltage of the low-load DC bus can be 12V, 24V, 48V and other safe voltages, which is suitable for the access of DC power sources such as low-power photovoltaics, fans, fuel cells and small-capacity energy storage batteries, and can power low-voltage DC devices such as handheld power tools and small communication equipment. The nominal voltage of the high-load DC bus can be 375V, 400V, 600V, 750V, 900V, etc., which is suitable for the access of DC power sources such as high-power photovoltaics, fans, fuel cells and large-capacity energy storage batteries, and can power high-power DC motor equipment (such as DC central air conditioners, electric servo cylinders, electric servo drives, etc.). The AC bus voltage is AC 220V / 380V and the frequency is 50Hz. It is suitable for the access of AC power sources such as mains electricity, DC internal combustion generator sets (diesel generator sets, gasoline generator sets, gas turbine generator sets, etc.), and can power various types of current mainstream AC power loads. The power threshold is set to 6kW, and the capacity threshold is set to 6kw·h. Power greater than 6kW is high power, and capacity greater than 6k·h is large capacity. Otherwise, it is low power and small capacity.

[0021] For small-power microgrids, an AC / DC hybrid microgrid architecture of low-energy-load DC bus + single-phase 220V AC bus is adopted. Multiple small-power microgrids (≥2) can be connected in parallel on the side of the DC bus with a nominal voltage of tens of volts or the single-phase 220V AC bus to expand the power supply capacity of the low-energy-load DC bus or the single-phase 220V AC. Multiple (3 sets and integer multiples of 3) small-power microgrids can also be operated in staggered phases (the phase difference between the 3 sets is 120°) to build a 380V AC bus, thereby supplying power to 380V AC loads.

[0022] The high-power microgrid adopts an AC / DC hybrid microgrid architecture of a high-load DC bus + a three-phase 380V AC bus. Multiple high-power microgrids can be connected in parallel on the DC bus with a nominal voltage of several hundred volts or a three-phase 380V AC bus to expand the high-load DC or 380V AC power supply capacity.

[0023] The small-power microgrid and the large-power microgrid can be connected in parallel through a 380V AC bus, thus building a three-bus microgrid of "low-load DC bus + high-load DC bus + AC bus". When the power supply capacity of the small-power microgrid is insufficient, the large-power microgrid can provide support power for the small-power microgrid; when the large-power microgrid fails or the energy is insufficient, multiple small-power microgrids can provide emergency support power for the large-power microgrid.

[0024] Various types of small-power microgrids and large-power microgrids that conform to the three-bus microgrid architecture can be quickly combined to build microgrid clusters of different sizes, and can also be quickly split from the microgrid cluster for independent use, realizing "gathered together as a ball of fire, scattered as stars in the sky", thereby meeting extremely diverse application needs based on a very small range of product series.

[0025] In summary, the three-bus microgrid architecture of low-load DC bus + high-load DC bus + AC bus of the present invention: takes into account the access of microgrids of different power levels and capacities, constructs small-power microgrids, high-power microgrids and interconnected microgrid groups to adapt to application scenarios with different power requirements; the microgrid supports plug-and-play, and can use multiple different microgrids to quickly build a microgrid group, or quickly split the microgrid group into multiple microgrids: the power between the microgrids in the microgrid group is interconnected, and the output power can be flexibly expanded; the microgrids in the microgrid group are temporarily split for external use, which improves the flexibility of use; 3 or more sets of small-power microgrids can be operated in staggered phases: three single-phase 220V outputs are combined into three-phase 380V outputs, so that small-power microgrid products can supply power to high-power power loads. Example

[0026] Figure 1 The figure shows a three-bus AC / DC microgrid architecture based on wind, solar, diesel and hydrogen storage. Small-power and small-capacity wind, solar, diesel and hydrogen storage can form a small-power microgrid with a 48V DC bus + 220V single-phase AC bus, where the wind, solar and hydrogen storage are connected to the 48V DC bus, and the PCS (energy storage converter) and diesel generator set are connected to the 220V AC bus. The 48V DC bus can supply power to the DC load, and the 220V AC bus can supply power to the 220V AC load. The PCS of three or more small-power microgrids can run at a 120° phase difference, so that 380V AC can be output to the outside to supply power to the 380V AC load.

[0027] High-power and high-capacity wind, solar, diesel and hydrogen storage can form a high-power microgrid with a 600V DC bus + 380V AC bus, where wind, solar and hydrogen storage are connected to the 600V DC bus, PCS (energy storage converter) and diesel generator sets are connected to the 380V AC bus, the 600V DC bus can supply power to DC loads, and the 380V AC bus can supply power to 380V AC loads. Multiple (≥2) sets of PCS and diesel generator sets of high-power microgrids can run in parallel, thus providing power to higher-power 380V AC loads.

[0028] Figure 1 In the microgrid group shown, if any local distributed power source (photovoltaic power generation unit, wind power generation unit, energy storage unit, fuel cell unit, diesel generator set) and PCS fails, all DC loads and AC loads can operate normally. The microgrid can also be connected to the grid or external AC power supply.

[0029] Based on the above three-bus microgrid architecture, multiple sets of small-power microgrids and high-power microgrids can build a microgrid group to achieve power interconnection, mutual support and concentrated power expansion and application. At the same time, each microgrid in the microgrid group can be quickly split for external use, so that a wide power output range can be covered based on a very small series of products to meet extremely diverse application needs. For example, for microgrid products with four power levels of 500W, 6kW, 30kW, and 75kW, 12 sets of 500W products can output 6kW in parallel, 6 sets of 6kW products can output 36kW in parallel, 4 sets of 30kW products can output 120kW in parallel, and 4 sets of 75kW products can output 300kW in parallel. Based on the four power levels of 500W, 6kW, 30kW, and 75kW, multi-level expansion can be carried out to cover the power load demand of 500W~462kW, and support the power consumption of power loads such as 48V DC, 600V DC, 220V AC, and 380V AC. Therefore, microgrid products based on the three-busbar architecture will greatly improve the application applicability of microgrid products and eliminate problems such as "a big horse pulling a small cart" and "a small horse cannot pull a big cart".

[0030] Figure 2 The figure shows a 500W photovoltaic-storage-diesel microgrid, which consists of a portable photovoltaic module, a portable energy storage module, a portable diesel generator set, a 48V DC bus, a 220V AC bus and a microgrid control module, wherein the microgrid control module includes a PCS (energy storage converter), a photovoltaic controller and an energy management controller. The portable photovoltaic module and the portable energy storage module are connected to the 48V DC bus, the portable diesel generator set, the PCS (energy storage converter) and the external mains are connected to the 220V AC bus, the photovoltaic controller and the energy management controller control the output energy of the photovoltaic power generation unit and the energy storage unit, and thus form a 48V DC bus + 220V AC bus small power microgrid. The 48V DC bus can supply power to DC loads, and the 220V AC bus can supply power to AC loads. A single set of this small power microgrid can output 500W, and 12 sets can be connected in parallel to output 6kW. In addition, by controlling the phase angle of the output AC power of each small-power microgrid, the output AC power phase angles of the three small-power microgrids can be 120° different, forming a three-phase 380V, 1.5kW output microgrid, that is, a single set outputs 220V AC power, and 3×n (n=1~4) can output three-phase 380V AC power. Therefore, through modular networking, the 500W solar-storage-diesel microgrid can cover the single-phase 220V and three-phase 380V power demand of 500W~6kW.

[0031] Figure 3The figure shows a 30kW photovoltaic-diesel microgrid, which consists of a photovoltaic cabin, an energy storage cabin, a diesel cabin, a 600V DC bus, and a 380V AC bus. The energy storage cabin includes a PCS (energy storage converter), a high-voltage energy storage battery, a photovoltaic controller, and an energy management controller. The photovoltaic cabin and the high-voltage energy storage battery are connected to the 600V DC bus, the diesel cabin, the PCS (energy storage converter) and the external mains are connected to the 380V AC bus, and the photovoltaic controller and the energy management controller control the output energy of the photovoltaic power generation unit and the energy storage unit, thereby forming a high-power microgrid of 600V DC bus + 380V AC bus. The 600V DC bus can supply power to high-power DC loads, and the 380V AC bus can supply power to AC loads. A single set of this high-power microgrid can output 30kW, and 4 sets can be connected in parallel to output 120kW. Therefore, through modular networking, the 30kW photovoltaic-storage-diesel microgrid cabin can cover the three-phase 380V power demand of 30kW~120kW.

[0032] also, Figure 2 The 500W photovoltaic-storage-diesel microgrid shown can be connected to the AC bus of the 30kW photovoltaic-storage-diesel microgrid, forming a three-bus microgrid of "low-voltage DC bus + high-voltage DC bus + AC bus".

[0033] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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.

[0034] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A three-bus AC / DC microgrid architecture, characterized in that: include: Low-load DC bus, and connected small-power photovoltaic power generation units, small-power wind power generation units, small-power fuel cell units and small-capacity energy storage units. The nominal voltage of the low-load DC bus is 12V, 24V, and 48V, which is used to supply power to low-voltage DC loads; High-energy-load DC bus, as well as connected high-power photovoltaic power generation units, high-power wind power generation units, high-power fuel cell units and large-capacity energy storage batteries. The nominal voltage of the high-energy-load DC bus is 375V, 400V, 600V, 750V, and 900V, which is used to supply power to high-power DC loads; AC busbar, as well as connected mains, internal combustion generator sets and energy storage converters. The voltage of the AC busbar is 220 / 380V and the frequency is 50Hz, which is used to supply power to AC loads. The low-energy-load DC bus and 220V AC bus form a small-power microgrid, the high-energy-load DC bus and 380V AC bus form a high-power microgrid, and the small-power microgrid and the high-power microgrid are connected in parallel through the 380V AC bus to form a three-bus microgrid architecture of "low-energy-load DC bus + high-energy-load DC bus + AC bus".

2. The three-bus AC / DC microgrid architecture according to claim 1 is characterized in that: The small-power microgrid is an AC / DC hybrid microgrid architecture. Multiple small-power microgrids are connected in parallel on the low-voltage DC bus or 220V AC bus side to expand the low-voltage DC or 220V AC power supply capacity.

3. The three-bus AC / DC microgrid architecture according to claim 2 is characterized in that: Three or integer multiples of three small-power microgrids are operated in staggered phases with a phase difference of 120°, that is, a 380V AC bus is constructed to supply power to 380V AC loads.

4. The three-bus AC / DC microgrid architecture according to claim 1, characterized in that: The high-power microgrid is an AC / DC hybrid microgrid architecture. Multiple high-power microgrids are connected in parallel on the high-load DC bus or 380V AC bus side to expand the high-voltage DC or 380V AC power supply capacity.

5. The three-bus AC / DC microgrid architecture according to claim 1, characterized in that: When the power supply capacity of the small-power microgrid is insufficient, the large-power microgrid provides support for the small-power microgrid; When a high-power microgrid fails or has insufficient energy, multiple small-power microgrids provide emergency support and power to the high-power microgrid.

6. The three-bus AC / DC microgrid architecture according to claim 1, characterized in that: Microgrids support plug-and-play. Multiple sets of small-power microgrids and high-power microgrids form a microgrid group, which can be used in combination or split into multiple microgrids for independent use.

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