CN214204966U - Micro-grid structure based on fuel cell - Google Patents

Micro-grid structure based on fuel cell Download PDF

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Publication number
CN214204966U
CN214204966U CN202022607570.0U CN202022607570U CN214204966U CN 214204966 U CN214204966 U CN 214204966U CN 202022607570 U CN202022607570 U CN 202022607570U CN 214204966 U CN214204966 U CN 214204966U
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unit
power generation
converter
fuel cell
generation unit
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CN202022607570.0U
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林今
谢重阳
连利波
胡强
曾庆
高丹慧
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Sichuan Energy Internet Research Institute EIRI Tsinghua University
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Sichuan Energy Internet Research Institute EIRI Tsinghua University
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Abstract

The utility model provides a microgrid structure based on fuel cell, include, including connecting respectively in the electrical unit of direct current generating line, energy storage unit and load cell, the electrical unit include fuel cell unit and photovoltaic unit, the energy storage unit including connect respectively in the battery and the direct current constant current power supply of direct current generating line, electrical unit, energy storage unit and load cell all connect in energy control system. According to the scheme, the fuel cell, the photovoltaic cell and the wind power cell are added into the micro-grid, and the requirements of generating capacity in most of time are met by combining various power generation types; the power generation units simultaneously charge the storage battery and supply power for the load, and all the power generation units are connected into one storage battery without being respectively provided with the storage battery, so that the unified management of the storage batteries is facilitated, and meanwhile, the micro-grid structure is simplified.

Description

Micro-grid structure based on fuel cell
Technical Field
The utility model belongs to the technical field of the little electric wire netting, especially, relate to a microgrid structure based on fuel cell.
Background
The microgrid is also called a microgrid and refers to a small-sized power generation and distribution system composed of a distributed power supply, an energy storage device, an energy conversion device, a load, a monitoring and protection device and the like.
As fuel power generation technology matures, fuel cell power generation is increasingly being introduced into the microgrid. The fuel cell is used as a novel green energy source, can use liquid fuels such as methanol, ammonia water and the like, has the characteristics of high energy density, high conversion efficiency, stability, no noise and the like, is combined with a photovoltaic and a storage battery to form a photovoltaic-storage battery-fuel cell and a photovoltaic-storage-combustion complementary power generation system, can stabilize power fluctuation of photovoltaic power generation to a certain extent and make up for the problem of insufficient capacity of the storage battery. For example, chinese patent discloses a light-storage-combustion complementary power generation system [ application No.: CN201921254007.0], including a photovoltaic array and a high temperature solid oxide fuel cell, where output terminals of the photovoltaic array and the high temperature solid oxide fuel cell are respectively connected to a dc bus through a first electric energy conversion circuit and a second electric energy conversion circuit, the dc bus is connected to a dc load through a third electric energy conversion circuit, the dc bus is respectively connected to a photovoltaic storage battery and a fuel storage battery through a first bidirectional electric energy conversion circuit and a second bidirectional electric energy conversion circuit, and the photovoltaic array, the high temperature solid oxide fuel cell, the photovoltaic storage battery, the fuel storage battery and the dc load are all connected to a controller.
However, the above-mentioned solution has certain disadvantages, such as a problem of excessive discharge of the battery when the generated power is insufficient.
SUMMERY OF THE UTILITY MODEL
The utility model aims at the above-mentioned problem, provide a microgrid structure based on fuel cell.
In order to achieve the above purpose, the utility model adopts the following technical proposal:
a micro-grid structure based on a fuel cell comprises a power generation unit, an energy storage unit and a load unit which are connected to a direct-current bus respectively, wherein the power generation unit comprises a fuel electricity unit and a photovoltaic unit, the energy storage unit comprises a storage battery and a direct-current constant-current power supply which are connected to the direct-current bus respectively, and the power generation unit, the energy storage unit and the load unit are all connected to an energy control system.
In the above-mentioned micro-grid structure based on fuel cells, the fuel-electric unit includes a fuel-electric generating unit and a first DC/DC converter, the fuel-electric generating unit is connected to the DC bus through the first DC/DC converter, and both the first DC/DC converter and the fuel-electric generating unit are connected to the energy control system.
In the fuel cell-based micro-grid structure, the fuel power generation unit comprises an SOFC power generation unit.
In the above-mentioned micro-grid structure based on fuel cells, the photovoltaic unit includes a photovoltaic power generation unit and a second DC/DC converter, the photovoltaic power generation unit is connected to the DC bus through the second DC/DC converter, and both the photovoltaic power generation unit and the second DC/DC converter are connected to the energy control system.
In the above fuel cell-based microgrid structure, the second DC/DC converter includes two PI controllers, and the photovoltaic unit outputs a constant voltage to the DC bus through a constant voltage control method.
In the above-mentioned fuel cell-based microgrid structure, the power generation unit further comprises a wind power unit.
In the above-mentioned micro-grid structure based on fuel cells, the wind power unit includes a wind power generation unit and an AC/DC converter, the wind power generation unit is connected to the DC bus via the AC/DC converter, and both the wind power generation unit and the AC/DC converter are connected to the energy control system.
In the above-mentioned micro-grid structure based on fuel cells, the energy storage unit further includes a battery management system connected to the storage battery and the energy control system.
In the above-mentioned micro grid structure based on fuel cells, the storage battery is connected to the DC bus via a bidirectional DC/DC converter.
In the fuel cell-based micro-grid structure, the bidirectional DC/DC converter includes two PI controllers to control the DC bus voltage in a constant voltage mode.
The utility model has the advantages that: meanwhile, the fuel cell, the photovoltaic cell and the wind power cell are added into the microgrid, and the requirements of generating capacity in most of time are met by combining various power generation types; the power generation units simultaneously charge the storage batteries and supply power to the load, and all the power generation units are connected with one storage battery without being respectively provided with the storage batteries, so that the unified management of the storage batteries is facilitated, and meanwhile, the micro-grid structure is simplified; the energy storage unit is provided with a direct current constant current power supply, and can be put into the microgrid when the total power of the power generation unit is not enough to provide the power required by the load unit, so that the balance of the power supply and demand is further realized, and the over-discharge protection of the storage battery is realized.
Drawings
Fig. 1 is a schematic connection diagram of a fuel cell-based micro-grid structure according to the present invention;
fig. 2 is a connection block diagram of a fuel cell-based micro-grid structure according to the present invention;
fig. 3 is a flowchart of an operation control method of the fuel cell-based micro-grid structure according to the present invention.
Reference numeral, a direct current bus 1; a power generation unit 2; an energy storage unit 3; a storage battery 31; a direct current constant current power supply 32; a bidirectional DC/DC converter 33; a load unit 4; a wind power unit 5; a wind power generation unit 51; an AC/DC converter 52; a fuel-electric unit 6; a first DC/DC converter 61; a photovoltaic unit 7; a photovoltaic power generation unit 71; a second DC/DC converter 72; an energy control system 8; an energy data module 81; an energy management module 82.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1 and fig. 2, the present embodiment discloses a micro-grid structure based on fuel cells, including a power generation unit 2, an energy storage unit 3 and a load unit 4 respectively connected to a dc bus 1, where the power generation unit 2 includes a power generation unit 6 and a photovoltaic unit 7, the energy storage unit 3 includes a storage battery 31 and a dc constant current power supply 32 respectively connected to the dc bus 1, and the power generation unit 2, the energy storage unit 3 and the load unit 4 are all connected to an energy control system 8 to send operation data to the energy control system 8 and receive energy management scheduling of the energy control system 8;
the energy control system 8 comprises an energy data module 81 for collecting operation data of the power generation unit 2, the energy storage unit 3 and the load unit 4, and an energy management module 82 for performing energy management according to the operation data to achieve supply and demand power balance.
Specifically, the fuel cell 6 includes a fuel power generation unit connected to the DC bus 1 through a first DC/DC converter 61, and a first DC/DC converter 61, where the fuel power generation unit is preferably an SOFC power generation unit 62, and the first DC/DC converter 61 and the SOFC power generation unit 62 are both connected to the energy control system 8. Those skilled in the art will appreciate that the SOFC power generation unit 62 includes a raw material power module, a circulating water cooling module, a power generation module, etc., and each module is provided with a corresponding sensor module to collect and send the temperature, pressure, and flow rate of each link to the energy control system 8. Meanwhile, the first DC/DC converter 61 transmits the collected input voltage current and output voltage current to the energy control system 8.
Specifically, the photovoltaic unit 7 includes a photovoltaic power generation unit 71 and a second DC/DC converter 72, the photovoltaic power generation unit 71 is connected to the direct current bus 1 through the second DC/DC converter 72, and both the photovoltaic power generation unit 71 and the second DC/DC converter 72 are connected to the energy control system 8; the second DC/DC converter 72 includes two PI controllers, and the photovoltaic unit 7 outputs a constant voltage to the DC bus 1 through a constant voltage control method.
As will be appreciated by those skilled in the art, the constant voltage control method includes:
the second DC/DC converter 72 sends the collected signals of input voltage, input current, output voltage, output current and the like to the energy control system 8, the energy control system 8 transmits the difference value of the given output reference voltage and the actual output voltage of the photovoltaic unit to a first PI controller in the second DC/DC converter 72, the output reference current of the photovoltaic unit is obtained through calculation, the difference value of the output reference current and the actual output current of the photovoltaic unit is transmitted to a second PI controller in the second DC/DC converter 72, the PWM wave is modulated by the pulse width of the second DC/DC converter 72 through a current limiting link of the photovoltaic unit, the PWM wave is obtained and is finally input to a Boost circuit, and therefore constant voltage control of the photovoltaic unit is achieved.
Further, the energy storage unit 3 further includes a Battery Management System (BMS) connected to the battery 31 and the energy control system 8; the battery 31 is connected to the DC bus 1 through a bidirectional DC/DC converter 33, and the bidirectional DC/DC converter 33 includes two PI controllers to control the DC bus voltage in a constant voltage mode. The voltage of the direct current bus 1 is controlled in the constant voltage mode as follows: the bidirectional DC/DC converter 33 collects the voltage of the direct current bus 1, the difference value between the collected bus voltage and the bus voltage reference value is transmitted to a first PI controller in the bidirectional DC/DC converter 33, the output reference current of the storage battery 31 is obtained through calculation, the difference value between the output reference current of the storage battery 31 and the actual output current of the storage battery is transmitted to a second PI controller in the bidirectional DC/DC converter 33, and finally the current limiting link of the storage battery 31 is used as the input of a pulse width modulation PWM wave of the bidirectional DC/DC converter 33, so that the storage battery 31 controls the voltage of the direct current bus 1 in a constant voltage mode.
Further, the power generating unit 2 also comprises a wind power unit 5. The wind power unit 5 includes a wind power generation unit 51 and an AC/DC converter 52, the wind power generation unit 51 is connected to the DC bus 1 via the AC/DC converter 52, and both the wind power generation unit 51 and the AC/DC converter 52 are connected to the energy control system 8. The wind power generation unit adopts an aerodynamic model to describe conversion of wind energy and electric energy, the motor system adopts a direct-drive permanent magnet synchronous motor structure and comprises a wind wheel, a generator, a bridge rectifier circuit, a Boost chopper circuit and the like, the wind wheel, the generator, the bridge rectifier circuit, the Boost chopper circuit and the like are merged into a microgrid through an AC/DC converter 52 of a voltage type PWM converter, and the wind power generation unit works in a Maximum Power Point Tracking (MPPT) mode during normal operation.
Specifically, as shown in fig. 3, the energy management module 82 of the energy control system 8 can perform energy management to achieve supply and demand power balance by the following method:
1) the SoC of the storage battery is 20% -80%, when the power required by the load unit 4 is greater than the total power of the power generation unit 2, the storage battery 31 is started to discharge, the insufficient power is complemented by the storage battery 31, and the energy balance of the microgrid system is achieved;
2) the SoC of the storage battery is 20% -80%, when the power required by the load unit 4 is less than the total power of the power generation unit 2, the storage battery 31 is started to charge, and the surplus power is absorbed by the storage battery 31, so that the energy balance of the microgrid system is achieved;
3) when the SoC of the storage battery is greater than 80%, cutting off part or all of the power generation units 2 from the microgrid, and simultaneously starting the storage battery 31 to discharge until the SoC of the storage battery is less than a third set value, and then completely connecting the power generation units into the microgrid; in this embodiment, the power generation unit 6 in the power generation unit 2 is first disconnected from the microgrid, if the total power of the wind power unit 5 and the photovoltaic unit 7 is still greater than the power required by the load, the power generation units are all disconnected from the microgrid, the storage battery alone supplies power to the load, and until the SoC of the storage battery is less than 40%, the power generation units are all connected to the microgrid, so that the storage battery can be prevented from being overcharged. Or after the power generation unit 6 is disconnected from the microgrid, the wind power unit 5 or the photovoltaic unit 7 is disconnected, the power of the rest units is still larger than the power required by the load, then the power generation units are completely disconnected from the microgrid, and the storage battery independently supplies power to the load until the SoC of the storage battery is smaller than 40%.
4) The SoC of the storage battery is less than 20%, the power required by the load is certainly greater than the total power of all the power generation units 2, the direct-current constant-current power supply 32 is connected into the microgrid, the storage battery can be prevented from being overdischarged, insufficient power is provided for charging the storage battery at the same time, and the direct-current constant-current power supply 32 is disconnected from the microgrid until the SoC of the storage battery is greater than 60% or the power required by the load unit 4 is less than the total power of the power generation units 2 in the charging process.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications, additions and substitutions for the specific embodiments described herein may be made by those skilled in the art without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims (10)

1. The utility model provides a microgrid structure based on fuel cell, is including connecting respectively in power generation unit (2), energy storage unit (3) and load unit (4) of direct current bus (1), characterized in that, power generation unit (2) include fuel cell (6) and photovoltaic unit (7), energy storage unit (3) including connect respectively in battery (31) and direct current constant current power supply (32) of direct current bus (1), power generation unit (2), energy storage unit (3) and load unit (4) all connect in energy control system.
2. The fuel cell-based microgrid structure according to claim 1, characterized in that the fuel-electric unit (6) comprises a fuel-electric generating unit and a first DC/DC converter (61), the fuel-electric generating unit is connected to the direct current bus (1) through the first DC/DC converter (61), and the first DC/DC converter (61) and the fuel-electric generating unit are both connected to the energy control system.
3. The fuel cell-based microgrid structure of claim 2, wherein the fuel power generation units comprise SOFC power generation units (62).
4. The fuel cell-based microgrid structure according to claim 1, characterized in that the photovoltaic unit (7) comprises a photovoltaic power generation unit (71) and a second DC/DC converter (72), the photovoltaic power generation unit (71) being connected to the direct current bus (1) through the second DC/DC converter (72), the photovoltaic power generation unit (71) and the second DC/DC converter (72) being both connected to the energy control system.
5. The fuel cell-based microgrid structure according to claim 4, characterized in that the second DC/DC converter (72) comprises two PI controllers, and the photovoltaic unit (7) outputs a constant voltage to the direct current bus (1) through a constant voltage control.
6. The fuel cell based microgrid structure of claim 1, characterized in that the power generation unit (2) further comprises a wind power unit (5).
7. The fuel cell-based microgrid structure according to claim 6, characterized in that the wind power unit (5) comprises a wind power generation unit (51) and an AC/DC converter (52), the wind power generation unit (51) is connected to the direct current bus (1) through the AC/DC converter (52), and the wind power generation unit (51) and the AC/DC converter (52) are both connected to the energy control system.
8. The fuel cell based microgrid structure of claim 1, characterized in that the energy storage unit (3) further comprises a battery management system connected to the storage battery (31) and an energy control system.
9. The fuel cell based microgrid structure of claim 8, characterized in that the storage battery (31) is connected to the direct current bus (1) through a bidirectional DC/DC converter (33).
10. The fuel cell based microgrid structure of claim 9, characterized in that said bidirectional DC/DC converter (33) comprises two PI-controllers to control the DC bus voltage in a constant voltage mode.
CN202022607570.0U 2020-11-12 2020-11-12 Micro-grid structure based on fuel cell Active CN214204966U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202022607570.0U CN214204966U (en) 2020-11-12 2020-11-12 Micro-grid structure based on fuel cell

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202022607570.0U CN214204966U (en) 2020-11-12 2020-11-12 Micro-grid structure based on fuel cell

Publications (1)

Publication Number Publication Date
CN214204966U true CN214204966U (en) 2021-09-14

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