CN111381171A - Microgrid system and control method based on fuel cell test - Google Patents

Abstract

The invention discloses a micro-grid system based on fuel cell testing, comprising a DC micro-grid unit, an AC micro-grid unit, a bidirectional AC/DC inverter, a power distribution unit and an energy management unit. The microgrid unit, the alternating current microgrid unit, the bidirectional AC/DC inverter and the power distribution unit are connected in communication, the direct current microgrid unit and the alternating current microgrid unit are electrically connected through the bidirectional AC/DC inverter, and the power distribution unit It is electrically connected with the AC micro-grid unit; the DC micro-grid unit includes a fuel cell test unit and an energy storage unit, and the DC interfaces of the fuel cell test unit and the energy storage unit are respectively connected to the DC bus L1; also disclosed is a A control method for a microgrid system based on fuel cell testing. The invention avoids the energy waste of the conventional resistance type load consuming the electric energy generated by the fuel cell system through thermal energy, and also saves the extra electric energy consumption for cooling the resistance type load equipment.

Description

Microgrid system and control method based on fuel cell test

technical field

The invention belongs to the technical field of fuel cell testing and micro-grid, in particular to a micro-grid system and control method based on fuel cell testing.

Background technique

Large-scale research, validation and testing of fuel cell stacks, fuel cell systems and fuel cell engines are essential steps before fuel cell applications. Since the fuel cell itself is a power generation device that continuously consumes hydrogen, the first solution in the traditional performance test process is to use a resistive load to consume the electrical energy generated by the fuel cell system through thermal energy, resulting in a waste of resources and an increase in cost. . In addition, the commonly used electronic loads also need to dissipate heat such as a cooling tower, a large fan or even an air conditioner during the process of releasing heat energy to ensure the normal operation of the electronic load, so additional power is required. For the fuel cell power system for new energy vehicles, the power of which exceeds 30kW or even as high as 100kW, the test method using electronic load will generate a great waste of electric energy and the test cost will rise.

The second solution is to use a grid-feeding electronic load to feed back the electrical energy output during the fuel cell test to the grid. Although this solution can effectively avoid the heat consumption of the fuel cell during the test and discharge process, due to the complexity and diversity of the test process (such as frequent start-stop loading, acceleration, and test polarization curves, etc.) When feeding power to the power grid under certain circumstances, it will cause serious interference of high-frequency harmonics to the power grid, and it is difficult to deal with it, which seriously affects the power quality of the power grid, and even causes an impact on the power grid.

The third scheme is to obtain hydrogen by electrolyzing water to produce hydrogen from the electrical energy output during the fuel cell testing process and pass it into the fuel cell for recycling. However, the conversion efficiency of hydrogen into electricity during fuel cell operation is generally 50% (based on the low calorific value LHV of hydrogen), while the theoretical electrolysis efficiency of the electricity generated by electrolyzing water to hydrogen again is high (the apparent conversion efficiency is even up to 100% to 122%), but in order to increase the hydrogen production rate in industry, the power conversion efficiency is only 50% to 70% due to factors such as heating and the generated polarization overpotential. Then the complete cycle efficiency of hydrogen→fuel cell→electrolyzer→hydrogen is only 30%, the energy loss exceeds 70%, and the cost of the hydrogen production system by electrolysis (especially the solid electrolyte membrane electrolysis of water with precious metal platinum or iridium as catalyst) Hydrogen production system) is higher and has a shorter lifespan. Therefore, this solution is not economical, and there are problems of complicated system and complicated maintenance.

On the other hand, it is sometimes necessary to preheat the stack to be tested before the fuel cell test, to supply high-pressure air to the fuel cell when the fuel cell is started, and to supply the fuel cell with cooling water to control the temperature during the fuel cell test. The electrical energy required by the electric heating device for preheating, the cooling device for temperature control for the fuel cell, and the air compressor for supplying high-pressure air for the fuel cell generally comes from the external power grid, which further increases the cost of electricity consumption; especially for the purpose of The power configuration of the electric heating device to make the stack heat up quickly is large, and the energy consumption is serious. At this time, the electric power of the stack has not yet been started, and its power completely comes from the external power grid. This high dependence on the power grid occurs during power outages and peak electricity consumption There is a risk that the fuel cell will not be able to test during a power outage.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a micro-grid system and control method based on fuel cell testing.

In order to achieve the above object, the technical scheme of the present invention is achieved in this way:

An embodiment of the present invention provides a microgrid system based on fuel cell testing, including a DC microgrid unit, an AC microgrid unit, a bidirectional AC/DC inverter, a power distribution unit, and an energy management unit, the energy management units are respectively connected with The DC microgrid unit, the AC microgrid unit, the bidirectional AC/DC inverter and the power distribution unit are connected in communication, the DC microgrid unit and the AC microgrid unit are electrically connected through the bidirectional AC/DC inverter, and the power distribution unit is electrically connected. The unit is electrically connected to the AC micro-grid unit; the DC micro-grid unit includes a fuel cell test unit and an energy storage unit, and the DC interfaces of the fuel cell test unit and the energy storage unit are respectively connected to the DC bus L1.

In the above solution, the AC micro-grid unit includes a third circuit breaker, a power distribution cabinet, an auxiliary system unit and a miscellaneous load unit, and the power output ends of the power distribution cabinet are respectively connected to the auxiliary system unit and the miscellaneous load unit. The electrical equipment is electrically connected, and the AC interface of the power distribution cabinet is connected to the AC bus bar L2 via a third circuit breaker.

In the above solution, the fuel cell test unit includes a fuel cell test bench, a one-way DC/DC converter and a first circuit breaker, and the DC output end of the fuel cell to be tested in the fuel cell test bench corresponds to the The input end of the one-way DC/DC converter is electrically connected, and the output end of the one-way DC/DC converter is electrically connected to the DC bus L1 through the first circuit breaker.

In the above solution, the energy storage unit includes an energy storage battery pack, a battery management unit, a bidirectional DC/DC converter and a second circuit breaker, and the energy storage battery pack is electrically connected to one end of the bidirectional DC/DC converter. , the other end of the bidirectional DC/DC converter is electrically connected to the DC bus L1 through the second circuit breaker, and the battery management unit is connected to the energy storage battery pack through a low-voltage signal line.

In the above solution, the auxiliary system unit includes an air unit and a thermal management unit, and the high-pressure air output end of the air unit is connected to the air inlet of the fuel cell test bench of the fuel cell test unit in the DC microgrid unit through a pipeline. , the water circuit of the thermal management unit is respectively connected to the fuel cell test bench of the fuel cell test unit and the water circuit of the one-way DC/DC converter in the DC micro-grid unit through pipes.

In the above solution, the miscellaneous load units include sensitive loads and general loads; the sensitive loads include but are not limited to the full-time non-power-off electrical equipment in the fuel cell test laboratory and the entire park buildings such as data processing centers and computer rooms. Such general loads include but are not limited to the entire park buildings such as office buildings, canteens, lighting in dormitories and other electrical equipment.

In the above solution, the DC terminal of the bidirectional AC/DC inverter is electrically connected to the DC bus L1, and the AC terminal of the bidirectional AC/DC inverter is electrically connected to the AC bus L2, so as to realize the connection between the DC bus L1 and the AC bus. Bidirectional transfer of electrical energy between busbars L2.

In the above solution, the power distribution unit includes an external power distribution network and a common connection point including a controller; the external power distribution network is connected to the AC bus L2 of the AC microgrid unit through the common connection point after passing through the transformer to realize the connection with the AC microgrid unit. Bidirectional transfer of AC power between AC busbars L2.

In the above solution, the energy management unit communicates with the fuel cell test bench and the one-way DC/DC converter in the fuel cell test unit of the DC micro-grid unit, the battery management unit in the energy storage unit and the two-way converter respectively through the communication line. The DC/DC converter, the bidirectional AC/DC inverter and the PLC controller of the power distribution cabinet in the AC microgrid unit are connected to the controller of the electrical equipment of the air unit and the thermal management unit in the auxiliary system unit, The first circuit breaker in the fuel cell test unit of the DC micro-grid unit, the second circuit breaker in the energy storage unit and the voltage and current Hall sensor of the DC bus L1, the bidirectional AC/DC respectively through the low-voltage signal line The circuit breaker in the inverter, the third circuit breaker of the DC microgrid unit, the voltage and current Hall sensor of the AC bus L2, and the controller of the common connection point in the power distribution unit are connected.

The embodiment of the present invention also provides a control method for a microgrid system based on fuel cell testing, and the method is implemented by the following steps:

Step (1), the energy management unit starts a self-check, and confirms that the public connection point in the power distribution unit is in a disconnected state, so that the entire microgrid system enters the initial off-grid control mode;

Step (2), the energy management unit acquires the number of fuel cells to be tested and test parameters in the fuel cell test unit of the DC microgrid unit, and determines the total electricity Q ₁ generated by the fuel cell during the entire test process, according to the AC The electrical equipment of the auxiliary system unit in the microgrid unit and the power acquisition of the sensitive load and general load in the miscellaneous load unit The total power _Q2 required by each electrical equipment of the AC microgrid unit before the fuel cell test and during the fuel cell test The required total power Q′ ₂ , the SOC of the energy storage battery group is obtained through the DC micro grid unit, and the dischargeable amount Q ₃ when the energy storage battery group is discharged from the current SOC to the set SOC lower limit and the current SOC is charged to the set value is determined. _The required charge amount Q _{′ 3} when the _SOC upper _{limit of} the

If Q ₁ ≤Q′ ₂ +Q′ ₃ , and Q ₂ ≤ Q ₃ , enter the steady-state off-grid working mode;

If Q ₁ >Q' ₂ +Q' ₃ , or Q ₂ >Q ₃ , enter the transient grid-connected working mode.

In the above solution, the steady-state off-grid working mode is as follows: the energy management unit first sends the energy to the bidirectional DC/DC converter and the bidirectional AC/DC inverter of the energy storage unit in the DC microgrid unit. Start signal, and send a closing signal to the second circuit breaker of the energy storage unit in the DC microgrid unit and the grid-connected circuit breaker of the bidirectional AC/DC inverter at the same time, and store the energy storage battery pack of the energy storage unit The DC power is converted into a specified DC voltage through the bidirectional DC/DC converter and sent to the DC bus L1 of the DC microgrid unit, and then the bidirectional AC/DC inverter converts the DC power on the DC bus L1 into a specified DC voltage. Then the energy management unit sends a closing signal to the third circuit breaker in the AC microgrid unit to send the AC power on the AC bus L2 into the power distribution At the same time, it sends commands to the PLC controller in the power distribution cabinet of the AC microgrid unit to distribute the electrical energy received by the power distribution cabinet to the various electrical equipment and miscellaneous equipment in the air unit and thermal management unit of the auxiliary system unit. Sensitive load and general load of similar load units, each electrical equipment starts to work to provide air with a specific pressure for the fuel cell to be tested and make the fuel cell rise or stabilize to a set temperature; when the energy management unit receives the When the fuel cell test bench in the fuel cell test unit sends a signal that the fuel cell meets the test conditions, it sends a start-up test signal to the fuel cell test bench and closes the first circuit breaker. Chemical performance test, during which the generated electric energy is converted into a specified voltage by the unidirectional DC/DC converter and sent to the DC bus L1; at this time, the energy management unit monitors the voltage fluctuations of the DC bus L1 and the AC bus L2 in real time Situation: when it is detected that the voltage of the DC bus L1 and/or the AC bus L2 deviates from the set upper threshold of the bus balance voltage, a charging signal is sent to the bidirectional DC/DC converter of the energy storage unit in the DC microgrid unit, Charge the excess electric energy on the DC bus L1 into the energy storage battery pack, so that the voltage of the DC bus L1 and/or the AC bus L2 falls back to the set bus balance voltage; when the AC bus L2 and/or the DC bus L1 is monitored When the voltage deviates from the set lower limit threshold of the bus balance voltage or the fuel cell stops testing, a discharge signal is sent to the bidirectional DC/DC converter of the energy storage unit in the DC microgrid unit, and the stored energy in the energy storage battery pack Power is fed into the DC bus L1 and into the AC bus L2 via the bidirectional AC/DC inverter to bring the voltages of the DC bus L1 and the AC bus L2 back up to the set bus balance voltage.

In the above solution, the transient grid-connected working mode is as follows: the energy management unit firstly passes the direct current energy stored in the energy storage battery pack of the energy storage unit through the bidirectional DC/DC converter and the bidirectional AC/DC inverter. After secondary inversion, it is converted into a specified AC voltage and sent to the AC bus L2 of the AC micro-grid unit, and then the third circuit breaker in the AC micro-grid unit is closed to send the AC power on the AC bus L2 into the power distribution cabinet At the same time, the power distribution cabinet distributes the received electrical energy to each electrical equipment in the air unit and thermal management unit of the auxiliary system unit, as well as the sensitive load and general load of the miscellaneous load unit, and each electrical equipment starts to work. The test fuel cell provides air with a specific pressure and makes the fuel cell rise or stabilize to a set temperature; the fuel cell test bench starts to test the electrochemical performance of the fuel cell to be tested according to the preset parameters and working steps, and the generated electrical energy passes through The voltage of the one-way DC/DC converter is converted into a specified voltage and then sent to the DC bus L1; in the whole process, the energy storage battery pack of the energy storage unit in the DC microgrid unit is based on the voltage fluctuation of the DC bus L1 and the AC bus L2. Through charging and discharging, the voltage fluctuation of the DC bus L1 and the AC bus L2 is suppressed and the voltages of the two buses are balanced; and, when the state of charge SOC of the energy storage battery pack has dropped to the set lower limit, the The common connection point is closed to send the electric energy of the external power grid into the AC bus bar L2 to ensure the normal operation of the electrical equipment of the air unit and the thermal management unit in the auxiliary system unit of the AC microgrid unit and the sensitive loads in the miscellaneous load unit, and At this time, if the external power grid is in the valley power period, the two-way AC/DC inverter will charge the valley power of the external power grid into the storage after the AC power of the AC bus L2 undergoes AC-DC and DC/DC secondary inversion. In the energy battery pack; when the state of charge SOC of the energy storage battery pack has risen to the set upper limit and the fuel cell test is still in progress, the common connection point of the power distribution unit is closed, and the fuel cell generated during the test The DC power is fed into the external grid after DC/DC and DC-AC secondary inverters.

Compared with the prior art, the present invention stores the electric energy generated during the electrochemical test of the fuel cell in the energy storage battery, which not only avoids the waste of energy consumed by the conventional resistive load by consuming the electric energy generated by the fuel cell system through thermal energy, but also saves energy. Saves extra power consumption for cooling the resistive load;

On the other hand, compared with the traditional fuel cell test system, the generated electric energy can only be supplied to the auxiliary system during the fuel cell test, and the activation of the air compressor in the air unit and the activation of the electric heating device in the thermal management unit before the fuel cell test The energy storage battery is configured in the micro-grid system constructed by the present invention, so that the electric energy generated in the fuel cell test process has the characteristics of time shift, so that it can be efficiently and flexibly output to the fuel cell test auxiliary The high power consumption equipment of the system not only effectively alleviates the high dependence of the fuel cell test auxiliary system on the external power grid, but also ensures the normal operation of the fuel cell test and provides uninterrupted power supply for sensitive loads during mains power outages or peak power consumption; , which saves the electricity cost of high power consumption equipment such as electric heating water tanks, chillers and cooling towers, and realizes the efficient use of electric energy generated during fuel cell testing.

Description of drawings

FIG. 1 is a schematic structural diagram of a microgrid system based on fuel cell testing according to an embodiment of the present invention.

FIG. 2 is a flowchart of a control method of a microgrid system based on fuel cell testing according to an embodiment of the present invention.

Detailed ways

The embodiments of the present invention will be further described below with reference to the accompanying drawings, and the advantages and features of the present invention will become more apparent with the description. However, the embodiments are only exemplary and do not limit the scope of the present invention in any way. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

In addition, in order to better illustrate the present invention, numerous specific details are given in the following detailed description. It will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other embodiments, well-known methods, procedures, components and circuits are not described in detail so as to highlight the gist of the present invention.

An embodiment of the present invention provides a microgrid system based on fuel cell testing, as shown in FIG. 1 , which includes a DC microgrid unit 1 , an AC microgrid unit 2 , a bidirectional AC/DC inverter 3 , a power distribution unit 4 and An energy management unit (EMS) 5, which is connected in communication with the DC microgrid unit 1, the AC microgrid unit 2, the bidirectional AC/DC inverter 3 and the power distribution unit 4, respectively, and the DC microgrid unit 1 is electrically connected to the AC microgrid unit 2 through a bidirectional AC/DC inverter 3 , and the power distribution unit 4 is electrically connected to the AC microgrid unit 2 . in,

The DC microgrid unit 1 includes a fuel cell test unit 11 and an energy storage unit 12, and the DC interfaces of the fuel cell test unit 11 and the energy storage unit 12 are respectively connected to the DC bus L1.

Specifically, the fuel cell test unit 11 includes a fuel cell test stand 111 , a one-way DC/DC converter 112 and a first circuit breaker 113 . The DC output end of the fuel cell to be tested in the fuel cell test stand 111 is connected to the same. The corresponding input ends of the unidirectional DC/DC converters 112 are electrically connected, and the output ends of the unidirectional DC/DC converters 112 are connected to the DC bus L1 through the first circuit breaker 113 .

The fuel cell test bench 111 in the fuel cell test unit 11 is used to test and evaluate the polarization curve, electrochemical impedance spectroscopy (EIS) and electrochemical performance of the fuel cell under various simulated working conditions, and the The one-way DC/DC converter 112 sends the electric energy generated by the fuel cell during the testing process into the DC bus L1 after voltage conversion.

Further, the fuel cell test bench 111 in the fuel cell test unit 11 can be a single set or multiple sets to form a fuel cell test bench array, and each of the fuel cell test benches in the fuel cell test bench array can test The stations 111 work independently and do not interfere with each other; and the number of the one-way DC/DC converters 112 is consistent with the number of the fuel cell test stations 111 and forms a one-to-one correspondence.

Optionally, the fuel cell test bench 111 includes, but is not limited to, a hydrogen flow test unit, an air flow test unit, a water management unit, a thermal management unit, and a control unit, and the tested fuel cells include but are not limited to fuel cell single cells, Fuel cell stacks, fuel cell systems, fuel cell engines, etc.; moreover, different fuel cells have different configurations of the corresponding fuel cell test benches, as long as the tested fuel cell type and test parameters are the same as the fuel cell test The table can be matched. Similarly, the configuration parameters of the unidirectional DC/DC converter 112 corresponding to the fuel cell test bench 111 are also different due to the voltage and current of the fuel cell to be tested, as long as the voltage and current ranges that can be converted are the same The voltage and current output by the fuel cell can be matched. In other words, the fuel cell test benches 111 in the above fuel cell test bench array may be of the same type or of different types; correspondingly, the unidirectional DC/DC converter 112 may also be of the same type, or It can be of different types, but the input configuration parameters of each unidirectional DC/DC converter 112 must match the electrical output parameters of the fuel cell test bench 111 to which it is connected, and the output configuration parameters must also match those described above. The parameters such as voltage and current of the DC bus L1 are matched.

Specifically, the energy storage unit 12 includes an energy storage battery pack 121, a battery management unit (BMS) 122, a bidirectional DC/DC converter 123 and a second circuit breaker 124. The energy storage battery pack 121 is connected to the bidirectional DC One end of the /DC converter 123 is electrically connected, the other end of the bidirectional DC/DC converter 123 is electrically connected to the DC bus L1 through the second circuit breaker 124 , and the battery management unit 122 is connected to the DC bus L1 through a low-voltage signal line. The energy storage battery pack 121 is connected.

The energy storage battery pack 121 is used to realize the bidirectional transmission of DC power with the DC bus L1 through the bidirectional DC/DC converter 123: on the one hand, it receives the fuel cells in the fuel cell test unit 11 that generate electricity generated during the test process. The DC power and the valley power transmitted by the power distribution unit 4 via the bidirectional AC/DC inverter 3, on the other hand, provide the AC microgrid unit 2 via the bidirectional AC/DC inverter 3 Electric energy and feeding power to the power distribution unit 4 to provide power auxiliary services for peak regulation, frequency regulation and reactive power compensation for external power grids;

Optionally, the energy storage battery pack 121 adopts one or more of lead-acid batteries, lead-carbon batteries, lithium-ion batteries, flow batteries, sodium-sulfur batteries, and supercapacitors;

Preferably, the energy storage battery pack 121 preferably adopts a lithium titanate battery or an all-vanadium flow battery.

The battery management unit 122 is used to monitor the voltage, current and temperature of the energy storage battery pack 121, accurately estimate the state of charge SOC of the energy storage battery pack 121, and pass the data information collected in real time through the communication line It is transmitted to the energy management unit 5, and at the same time, energy is balanced among the single cells of the energy storage battery pack 121.

The AC microgrid unit 2 includes a third circuit breaker 23 , a power distribution cabinet 24 , an auxiliary system unit 21 and a miscellaneous load unit 22 , and the AC interface of the power distribution cabinet 24 is connected to the AC busbar L2 via the third circuit breaker 23 . Above, the power output ends of the power distribution cabinet 24 are respectively electrically connected to the electrical equipment of the auxiliary system unit 21 and the miscellaneous load unit 22 .

Specifically, the auxiliary system unit 21 includes an air unit 211 and a thermal management unit 212. The high-pressure air output end of the air unit 211 is connected to the fuel cell test unit 11 in the DC microgrid unit 1 through a pipeline for fuel cell testing. The air inlet of the bench 111 is connected, and the water circuit of the thermal management unit 212 is connected to the water circuit of the fuel cell test bench 111 and the one-way DC/DC converter 112 of the fuel cell test unit 11 in the DC microgrid unit 1 through pipes respectively. connect.

Further, the electrical equipment of the air unit 211 at least includes an air compressor, which is used to provide high-pressure air for the fuel cell in the on-line test; the electrical equipment of the thermal management unit 212 at least includes a pure water machine, an electric heating water tank , water pump, chiller and/or cooling tower and other electrical equipment, the electric heating water tank is used to provide high temperature medium such as hot water for the battery preheating before the fuel cell test, the chiller and/or cooling tower are used for During the fuel cell test, the fuel cell and the unidirectional DC/DC converter 112 are provided with a cooling medium such as cooling water to control the operating temperature of the fuel cell and the unidirectional DC/DC converter 112 .

Specifically, the miscellaneous load unit 22 includes a sensitive load 221 and a general load 222. The sensitive load 221 includes but is not limited to the full-time non-power-off electrical equipment in the fuel cell test laboratory and the data such as data in the entire park building. Processing centers, computer rooms and other electrical equipment that cannot be cut off at all times. The general load 222 includes but is not limited to electrical equipment in the entire park building such as office buildings, canteens, and lighting in dormitories.

The DC terminal of the bidirectional AC/DC inverter 3 is electrically connected to the DC bus L1, and the AC terminal of the bidirectional AC/DC inverter 3 is electrically connected to the AC bus L2 for realizing the DC bus L1 and the AC bus L2. Bidirectional transfer of electrical energy between them.

The power distribution unit 4 includes an external power distribution network 401 and a common connection point (PCC) 402 containing a controller; the external power distribution network 401 is connected to the AC microgrid unit 2 through the common connection point 402 after passing through the transformer. The AC bus L2 realizes the bidirectional transmission of AC power with the AC bus L2: on the one hand, the AC microgrid unit 2 is directly provided with AC power under certain circumstances and the power when the power consumption is at a low point is reversed through the two-way AC/DC. The inverter 3 is stored in the energy storage unit 12 of the DC micro-grid unit 1 , and on the other hand, the fuel cell test unit 11 of the DC micro-grid unit 1 receives the transmission from the bidirectional AC/DC inverter 3 in the fuel cell test unit 11 . The excess direct current electric energy generated by the fuel cell during the test process and the electric energy released by the energy storage unit 12 and the reactive power generated during the peak power consumption.

The energy management unit 5 communicates with the fuel cell test bench 111 and the one-way DC/DC converter 112 in the fuel cell test unit 11 of the DC micro-grid unit 1, respectively, and the battery management in the energy storage unit 12 through the communication line Unit 122 and bidirectional DC/DC converter 123, the bidirectional AC/DC inverter 3 and the PLC controller of the power distribution cabinet 24 in the AC microgrid unit 2 and the air unit 211 and thermal management in the auxiliary system unit 21 The controller of the electrical equipment of the unit 212 is connected to the first circuit breaker 113 in the fuel cell test unit 11 of the DC microgrid unit 1, the second circuit breaker 124 in the energy storage unit 12 and the The voltage and current Hall sensor of the DC bus L1, the circuit breaker in the bidirectional AC/DC inverter 3, the third circuit breaker 23 of the DC microgrid unit 2, the voltage and current Hall sensor of the AC bus L2, and all The controller connection of the common connection point 402 in the power distribution unit 4 is used to receive the real-time parameter information of the fuel cell test unit 11, the energy storage unit 12, the auxiliary system unit 21 and the DC bus L1 and the AC bus L2, by recording , Count and analyze the power operation data of the entire micro-grid system, and transmit to the fuel cell test unit 11, the energy storage unit 12, the auxiliary system unit 21, the miscellaneous load unit 22, the bidirectional AC/DC inverter according to the preset command The controller 3 and the control elements and circuit breakers of the power distribution unit 4 issue operation instructions to comprehensively manage and dispatch the fuel cell test, energy storage, auxiliary system and miscellaneous load power consumption and power grid energy exchange, so that the entire microgrid system can operate at the most in good condition and achieve better economic benefits.

The microgrid system based on the fuel cell test works in a steady-state off-grid working mode and a transient grid-connected working mode:

In the steady-state off-grid working mode, the DC power stored in the energy storage battery pack 121 of the energy storage unit 12 in the DC microgrid unit 1 is converted into a specified DC voltage via the bidirectional DC/DC converter 123 and sent to the DC The DC bus L1 of the microgrid unit 1, then the bidirectional AC/DC inverter 3 converts the DC power on the DC bus L1 into a specified AC voltage and sends it to the AC bus L2 of the AC microgrid unit 2; The third circuit breaker 23 in the AC microgrid unit 2 is closed to send the AC power on the AC bus L2 into the power distribution cabinet 24, while the PLC controller of the power distribution cabinet 24 in the AC microgrid unit 2 sends the power distribution cabinet 24. The received electrical energy is distributed to the various electrical equipment in the air unit 211 and the thermal management unit 212 of the auxiliary system unit 21, as well as the sensitive load 221 and the general load 222 of the miscellaneous load unit 22, and each electrical equipment starts to work as a standby. The test fuel cell provides air with a specific pressure and makes the fuel cell rise or stabilize to a set temperature; then the fuel cell test bench 111 tests the electrochemical performance of the fuel cell to be tested according to the preset parameters and steps, and the electric energy generated during the test After being converted into a predetermined voltage by the one-way DC/DC converter 112, the voltage is sent to the DC bus L1. At this time, the energy storage battery pack 121 of the energy storage unit 12 in the DC microgrid unit 1 suppresses and balances the voltage fluctuations of the DC bus L1 and the AC bus L2 by charging and discharging according to the voltage fluctuations of the DC bus L1 and the AC bus L2 The voltages of the two buses: when the voltage of the DC bus L1 and/or the AC bus L2 deviates from the upper threshold of the set bus balance voltage, the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1 The excess electric energy on the DC bus L1 will be charged into the energy storage battery pack 121 to make the voltage of the DC bus L1 and/or the AC bus L2 fall back to the set bus balance voltage; when the AC bus L2 and/or the DC bus L1 When the voltage deviates from the set lower limit threshold of the bus balance voltage or the fuel cell stops testing, the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1 converts the energy stored in the energy storage battery pack 121 into the DC bus L1 and into the AC bus L2 via the bidirectional AC/DC inverter 3 to make the voltages of the DC bus L1 and the AC bus L2 return to the set bus balance voltage to maintain the AC microgrid unit 2 The necessary electrical equipment in the auxiliary system unit 21 and the normal power supply of the sensitive loads 221 and general loads 222 in other load units 22 .

During the entire working process of the microgrid system, electrical energy is only transferred between the fuel cell test unit 11, the energy storage unit 12, the auxiliary system unit 21, and the miscellaneous load unit 22. The common connection point of the power distribution unit 4 PCC402 is always disconnected, and the entire microgrid system operates in an island.

In the transient grid-connected working mode, the DC power stored in the energy storage battery pack 121 of the energy storage unit 12 in the DC microgrid unit 1 is converted into a specified DC voltage via the bidirectional DC/DC converter 123 and sent to the DC The DC bus L1 of the microgrid unit 1, then the bidirectional AC/DC inverter 3 converts the DC power on the DC bus L1 into a specified AC voltage and sends it to the AC bus L2 of the AC microgrid unit 2; The third circuit breaker 23 in the AC microgrid unit 2 is closed to send the AC power on the AC bus L2 into the power distribution cabinet 24, while the PLC controller of the power distribution cabinet 24 in the AC microgrid unit 2 sends the power distribution cabinet 24. The received electrical energy is distributed to the various electrical equipment in the air unit 211 and the thermal management unit 212 of the auxiliary system unit 21, as well as the sensitive load 221 and the general load 222 of the miscellaneous load unit 22, and each electrical equipment starts to work as a standby. The test fuel cell provides air with a specific pressure and makes the fuel cell rise or stabilize to a set temperature; then the fuel cell test bench 111 tests the electrochemical performance of the fuel cell to be tested according to the preset parameters and steps, and the electric energy generated during the test After being converted into a predetermined voltage by the one-way DC/DC converter 112, the voltage is sent to the DC bus L1.

During the entire microgrid operation process, the energy storage battery pack 121 of the energy storage unit 12 in the DC microgrid unit 1 suppresses the DC bus L1 and the AC bus L2 by charging and discharging according to the voltage fluctuations of the DC bus L1 and the AC bus L2 The voltage fluctuates and balances the voltages of the two busbars:

When the voltage of the AC bus L2 and/or the DC bus L1 deviates from the set lower limit threshold of the bus balance voltage or the fuel cell stops the test, the bidirectional DC/DC converter 123 of the energy storage unit 11 in the DC microgrid unit 1 will The electric energy stored in the energy storage battery pack 121 is sent into the DC bus L1 and into the AC bus L2 via the bidirectional AC/DC inverter 3 to make the voltages of the DC bus L1 and the AC bus L2 return to the set bus balance voltage to maintain the normal power supply of the necessary electrical equipment in the auxiliary system unit 21 in the AC microgrid unit 2 and the sensitive loads 221 and general loads 222 in the miscellaneous load unit 22; When the electrical state SOC has dropped to the set lower limit, the common connection point PCC402 of the power distribution unit 4 is closed to send the electric energy of the external power grid 401 into the AC bus L2 to ensure the auxiliary system unit 21 of the AC microgrid unit 2 The electrical equipment of the air unit 211 and the thermal management unit 212 and the sensitive loads 221 in the miscellaneous load unit 22 work normally, and if the external power grid 401 is in the valley power period at this time, the bidirectional AC/DC inverter 3 will The AC power of the AC bus L2 is converted into a DC voltage matching the DC bus L1 through AC-DC and then sent to the DC bus L1, and the valley power of the external power grid 401 is charged into the energy storage through the bidirectional DC/DC converter 123 in the battery pack 121 .

When the voltage of the DC bus L1 and/or the AC bus L2 deviates from the set upper threshold of the bus balance voltage, the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1 will convert the DC bus L1 The excess electric energy is charged into the energy storage battery pack 121, so that the voltage of the DC bus L1 and/or the AC bus L2 falls back to the set bus balance voltage; in this process, when the state of charge SOC of the energy storage battery pack 121 has When the fuel cell test is still in progress, the common connection point PCC402 of the power distribution unit 4 is closed, and the DC power generated by the fuel cell during the test passes through the DC/DC and DC-AC secondary stages. After inversion, it is fed into the external power grid 401 .

The invention stores the electric energy generated in the electrochemical test process of the fuel cell in the energy storage battery, which not only avoids the waste of energy consumed by the conventional resistance type load of the electric energy generated by the fuel cell system through thermal energy, but also saves the energy consumption for the resistance type load. Additional power consumption for cooling equipment.

On the other hand, compared with the traditional fuel cell test system, the generated electric energy can only be supplied to the auxiliary system during the fuel cell test, and the activation of the air compressor in the air unit and the activation of the electric heating device in the thermal management unit before the fuel cell test The energy storage battery is configured in the micro-grid system constructed by the present invention, so that the electric energy generated in the fuel cell test process has the characteristics of time shift, so that it can be efficiently and flexibly output to the fuel cell test auxiliary The high power consumption equipment of the system not only effectively alleviates the high dependence of the fuel cell test auxiliary system on the external power grid, but also ensures the normal operation of the fuel cell test and provides uninterrupted power supply for sensitive loads during mains power outages or peak power consumption; , which saves the electricity cost of high power consumption equipment such as electric heating water tanks, chillers and cooling towers, and realizes the efficient use of electric energy generated during fuel cell testing.

In addition, the existence of the energy storage unit in the micro-grid system of the present invention also avoids the serious interference of the high-frequency harmonics of the power grid caused by the usual feeder-type electronic load, and effectively suppresses the high-power electric heating water tank from starting and rapidly heating up the power grid. impact, effectively improve the power factor of the external power grid; on the other hand, it can realize peak shaving, harmonic control and reactive power compensation of the external power grid, and improve the power quality of the power grid; at the same time, the use of energy storage battery packs can also pass the valley power Power ancillary services such as peak usage, peak regulation and frequency regulation bring additional benefits to enterprises.

An embodiment of the present invention also provides a method for controlling a microgrid system based on fuel cell testing, as shown in FIG. 2 , the method is implemented through the following steps:

In step 200, the energy management unit 5 starts a self-check, and confirms that the common connection point 402 of the power distribution unit 4 is in a disconnected state, so that the entire microgrid system enters the initial off-grid control mode. Then go to step 201 .

In step 201, the energy management unit 5 obtains the number and test parameters of the fuel cells to be tested in the fuel cell test unit 11 of the DC microgrid unit 1 to calculate the total electricity Q generated by the fuel cells during the entire test process _1. According to the power of the electrical equipment in the auxiliary system unit 21 of the AC microgrid unit 2 and the power of the sensitive load 221 and the general load 222 in the miscellaneous load unit 22, obtain the power required by each electrical equipment of the AC microgrid unit 2 before the fuel cell test. The total power Q ₂ and the total power Q′ ₂ required in the fuel cell test process are obtained through the battery management unit 122 in the energy storage unit 12 of the DC microgrid unit 1 to obtain the SOC of the energy storage battery pack 121 to calculate the energy storage battery pack 121 The dischargeable amount Q ₃ when the current SOC is discharged to the set SOC lower limit and the chargeable amount Q′ ₃ when the current SOC is charged to the set SOC upper limit; then compare Q ₁ , Q ₂ , Q′ ₂ , Q ₃ and _Q'3 and enter step 202.

In step 202, when the energy management unit 5 detects that Q ₁ ≤ Q' ₂ +Q' ₃ and Q ₂ ≤ Q ₃ , it will enter step 210, that is, enter the steady-state off-grid working mode; When ₁ >Q' ₂ +Q' ₃ or Q ₂ >Q ₃ , then enter step 220, that is, enter the transient grid-connected working mode.

In step 210, the energy management unit 5 first sends a start signal to the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1 and the bidirectional AC/DC inverter 3, and at the same time Send a closing signal to the second circuit breaker 124 of the energy storage unit 12 in the DC microgrid unit 1 and the grid-connected circuit breaker of the bidirectional AC/DC inverter 3, and the energy storage battery pack of the energy storage unit 12 The DC power stored in 121 is converted into a specified DC voltage via the bidirectional DC/DC converter 123 and sent to the DC bus L1 of the DC microgrid unit 1, and then the bidirectional AC/DC inverter 3 converts the DC power on the DC bus L1. The DC power is converted into a specified AC voltage and sent to the AC bus L2 of the AC micro-grid unit 2; then the energy management unit 5 sends a closing signal to the third circuit breaker 23 in the AC micro-grid unit 2 to connect the AC bus. The AC power on L2 is sent to the power distribution cabinet 24, and at the same time, a command is sent to the PLC controller of the power distribution cabinet 24 in the AC microgrid unit 2 to distribute the power received by the power distribution cabinet 24 to the auxiliary system unit 21. The various electrical devices in the air unit 211 and the thermal management unit 212, as well as the sensitive loads 221 and the general loads 222 of the miscellaneous load unit 22, each electrical device starts to work to provide air with a specific pressure for the fuel cell to be tested and make the fuel cell rise. to or stabilized to the set temperature; when the energy management unit 5 receives a signal from the fuel cell test bench 111 in the fuel cell test unit 11 that the fuel cell meets the test conditions, it sends a signal to the fuel cell test bench 111 The test signal is activated and the first circuit breaker 113 is closed, and the electrochemical performance test of the fuel cell to be tested is carried out according to the preset parameters and working steps, and the electric energy generated during the voltage is converted into a specified voltage by the one-way DC/DC converter 112 and sent to the into the DC bus L1.

During the whole working process of the microgrid system, electric energy is only transferred between the DC microgrid unit 1 and the AC microgrid unit 2, and the common connection point PCC402 of the power distribution unit 4 is always disconnected. The system operates in an island; and, the energy management unit monitors the voltage fluctuations of the DC bus L1 and the AC bus L2 in real time, and goes to step 211 .

In step 211, the energy management unit 5 first starts to detect whether the voltage of the DC bus L1 and/or the AC bus L2 deviates from the set upper limit threshold of the bus balance voltage: if it deviates from the upper limit, go to step 212, if it does not deviate from the upper limit, then Go to step 213.

In step 212, the energy management unit 5 sends a charging signal to the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1, and charges the excess electric energy on the DC bus L1 into the energy storage battery pack In step 121, the voltage of the DC bus L1 and/or the AC bus L2 is dropped back to the set bus balance voltage.

In step 213, the energy management unit 5 starts to detect whether the voltage of the DC bus L1 and/or the AC bus L2 deviates from the set lower limit threshold of the bus balance voltage or the fuel cell stops the test: if so, go to step 214 , if not, return to step 211.

In step 214, the energy management unit 5 sends a discharge signal to the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1, and sends the electric energy stored in the energy storage battery pack 121 into the DC bus L1 and the AC bus L2 sent through the bidirectional AC/DC inverter 3 to make the voltages of the DC bus L1 and the AC bus L2 return to the set bus balance voltage to maintain the auxiliary system units in the AC microgrid unit 2 Necessary electrical equipment in 21 and normal power supply of sensitive loads 221 and general loads 222 in the miscellaneous load unit 22 .

In step 220, the energy management unit 5 first sends a start signal to the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1 and the bidirectional AC/DC inverter 3, and at the same time Send a closing signal to the second circuit breaker 124 of the energy storage unit 12 in the DC microgrid unit 1 and the grid-connected circuit breaker of the bidirectional AC/DC inverter 3, and the energy storage battery pack of the energy storage unit 12 The DC power stored in 121 is converted into a specified DC voltage via the bidirectional DC/DC converter 123 and sent to the DC bus L1 of the DC microgrid unit 1, and then the bidirectional AC/DC inverter 3 converts the DC power on the DC bus L1. The DC power is converted into a specified AC voltage and sent to the AC bus L2 of the AC micro-grid unit 2; then the energy management unit 5 sends a closing signal to the third circuit breaker 23 in the AC micro-grid unit 2 to connect the AC bus. The AC power on L2 is sent to the power distribution cabinet 24, and at the same time, a command is sent to the PLC controller of the power distribution cabinet 24 in the AC microgrid unit 2 to distribute the power received by the power distribution cabinet 24 to the auxiliary system unit 21. The various electrical devices in the air unit 211 and the thermal management unit 212, as well as the sensitive loads 221 and the general loads 222 of the miscellaneous load unit 22, each electrical device starts to work to provide air with a specific pressure for the fuel cell to be tested and make the fuel cell rise. to or stabilized to the set temperature; when the energy management unit 5 receives a signal from the fuel cell test bench 111 in the fuel cell test unit 11 that the fuel cell meets the test conditions, it sends a signal to the fuel cell test bench 111 The test signal is activated and the first circuit breaker 113 is closed, and the electrochemical performance test of the fuel cell to be tested is carried out according to the preset parameters and working steps, and the electric energy generated during the voltage is converted into a specified voltage by the one-way DC/DC converter 112 and sent to the into the DC bus L1.

During the entire microgrid operation process, the energy management unit 5 monitors the voltage fluctuations of the DC bus L1 and the AC bus L2 in real time and tracks the load of the energy storage battery pack 121 in the energy storage unit 12 of the DC microgrid unit 1 in real time Changes in the electrical state SOC, and go to step 221 .

In step 221, the energy management unit 5 first starts to detect whether the voltage of the DC bus L1 and/or the AC bus L2 deviates from the set upper limit threshold of the bus balance voltage: if it deviates from the upper limit, go to step 222, if it does not deviate from the upper limit, then Go to step 226.

In step 222, the energy management unit 5 sends a charging signal to the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1, and charges the excess electric energy on the DC bus L1 into the energy storage battery pack In step 121 , the voltage of the DC bus L1 and/or the AC bus L2 falls back to the set bus balance voltage, and the process proceeds to step 223 .

In step 223, the energy management unit 5 detects in real time whether the state of charge SOC of the energy storage battery pack 121 has risen to the set upper limit while the fuel cell test is still in progress. If it reaches the upper limit and the fuel cell has stopped the test, go to step 224 , if it has risen to the set upper limit and the fuel cell test is still in progress, go to step 225 .

In step 224, the common connection point PCC 402 in the power distribution unit 4 remains disconnected.

In step 225, the energy management unit 5 sends a closing signal to the common connection point PCC402 of the power distribution unit 4, and the DC power generated by the fuel cell during the test process passes through the voltage of the one-way DC/DC converter 112 After conversion, it is sent to the DC bus L1, and then converted into AC power by the bidirectional AC-DC inverter 3, then sent to the AC bus, and then fed into the external power grid 401 through the common connection point PCC402.

In step 226, the energy management unit 5 first starts to detect whether the voltage of the DC bus L1 and/or the AC bus L2 deviates from the set lower limit threshold of the bus balance voltage or the fuel cell test has stopped: if it deviates from the lower limit or the fuel cell test If it has stopped, go to step 227 , if the upper limit is not deviated or the fuel cell test has not stopped, go back to step 221 .

In step 227, the energy management unit 5 sends a discharge signal to the bidirectional DC/DC converter 123 of the energy storage unit 12 in the DC microgrid unit 1, and transfers the electrical energy stored in the energy storage battery pack 121 through the bidirectional DC/DC The voltage of the converter 123 is converted and sent to the DC bus L1, and then converted into alternating current through the bidirectional DC/AC inverter 3, and then sent to the AC bus L2, so that the voltage of the DC bus L1 and/or the AC bus L2 is returned to The set busbar balance voltage is used to maintain the normal power supply of the necessary electrical equipment in the auxiliary system unit 21 in the AC microgrid unit 2 and the sensitive loads 221 and general loads 222 in the miscellaneous load unit 22 , and proceed to step 228 .

In step 228, the energy management unit 5 detects in real time whether the state of charge SOC of the energy storage battery pack 121 has dropped to the set lower limit. If the lower limit is set, go to step 230 .

In step 229, the common connection point 402 in the power distribution unit 4 continues to remain disconnected.

In step 230, the energy management unit 5 sends a closing signal to the common connection point 402 of the power distribution unit 4, and the AC power of the external power grid 401 is fed into the AC bus L2 through the common connection point 402 to make the voltage rise to the set point. The predetermined busbar balance voltage can ensure the normal operation of the electrical equipment of the air unit 211 and the thermal management unit 212 in the auxiliary system unit 21 of the AC microgrid unit 2 and the sensitive load 221 in the miscellaneous load unit 22; and if at this time, if When the external power grid 401 is in a valley period, the energy management unit 5 sends an AC-DC inverter signal to the bidirectional AC/DC inverter 3 to invert the AC power of the AC bus L2 to match the DC bus L1 The DC voltage is sent to the DC bus L1, and the valley power of the external power grid 401 is charged into the energy storage battery pack 121 via the bidirectional DC/DC converter 123.

The contents of the embodiments of the present invention are disclosed as above. However, the present embodiments are not intended to limit the scope of the present invention. Simple equivalent changes and modifications made according to the claims and descriptions of the present invention still belong to the technical solutions of the present invention. within the range.

Claims (12)

1. A microgrid system based on fuel cell testing, characterized in that, comprising a DC microgrid unit, an alternating current microgrid unit, a bidirectional AC/DC inverter, a power distribution unit and an energy management unit, the energy management units are respectively It is connected in communication with the DC microgrid unit, the AC microgrid unit, the bidirectional AC/DC inverter and the power distribution unit, and the DC microgrid unit is electrically connected with the AC microgrid unit through the bidirectional AC/DC inverter. The electrical unit is electrically connected to the AC microgrid unit; the DC microgrid unit includes a fuel cell test unit and an energy storage unit, and the DC interfaces of the fuel cell test unit and the energy storage unit are respectively connected to the DC bus L1. 2 . The microgrid system based on fuel cell testing according to claim 1 , wherein the AC microgrid unit comprises a third circuit breaker, a power distribution cabinet, an auxiliary system unit and a miscellaneous load unit, and the The power output ends of the electrical cabinet are respectively electrically connected to the electrical equipment of the auxiliary system unit and the miscellaneous load unit, and the AC interface of the power distribution cabinet is connected to the AC bus bar L2 via the third circuit breaker. 3. The fuel cell testing-based microgrid system according to claim 1 or 2, wherein the fuel cell testing unit comprises a fuel cell testing bench, a one-way DC/DC converter and a first circuit breaker, wherein the The DC output end of the fuel cell to be tested in the fuel cell test bench is electrically connected to the corresponding input end of the unidirectional DC/DC converter, and the output end of the unidirectional DC/DC converter passes through the first circuit breaker It is electrically connected to the DC bus L1. 4 . The microgrid system based on fuel cell testing according to claim 3 , wherein the energy storage unit comprises an energy storage battery pack, a battery management unit, a bidirectional DC/DC converter and a second circuit breaker, the The energy storage battery pack is electrically connected to one end of the bidirectional DC/DC converter, the other end of the bidirectional DC/DC converter is electrically connected to the DC bus L1 through the second circuit breaker, and the battery management unit is electrically connected to the DC bus L1 through the second circuit breaker. The low-voltage signal line is connected to the energy storage battery pack. 5 . The microgrid system based on fuel cell testing according to claim 4 , wherein the auxiliary system unit comprises an air unit and a thermal management unit, and a high-pressure air output end of the air unit is connected to the direct current through a pipe. 6 . The air inlet of the fuel cell test unit of the fuel cell test unit in the microgrid unit is connected to the air inlet of the fuel cell test unit, and the water path of the thermal management unit is respectively connected with the fuel cell test bed of the fuel cell test unit in the DC microgrid unit and the one-way through pipes. Water connections for DC/DC converters. 6 . The fuel cell testing-based microgrid system according to claim 5 , wherein the miscellaneous load units include sensitive loads and general loads; the sensitive loads include but are not limited to all fuel cell testing laboratories. 7 . The electrical equipment that cannot be cut off at all times and the electrical equipment that cannot be cut off at all times in the entire park building such as data processing center, computer room, etc. The general load includes but is not limited to the entire park building such as office buildings, canteens, lighting in dormitories, etc. Electrical equipment. 7 . The fuel cell test-based microgrid system according to claim 6 , wherein the DC terminal of the bidirectional AC/DC inverter is electrically connected to the DC bus L1 , and the bidirectional AC/DC inverter is electrically connected to the DC bus L1 . The AC end of the device is electrically connected to the AC bus bar L2 for realizing bidirectional transmission of electric energy between the DC bus bar L1 and the AC bus bar L2. 8 . The fuel cell test-based microgrid system according to claim 7 , wherein the power distribution unit includes an external power distribution network and a common connection point including a controller; the external power distribution network passes through a transformer. The AC busbar L2 of the AC microgrid unit is connected to the AC busbar L2 through a common connection point to realize bidirectional transmission of AC power with the AC busbar L2. 9 . The fuel cell test-based microgrid system according to claim 8 , wherein the energy management unit communicates with the fuel cell test bench and the fuel cell test bench in the fuel cell test unit of the DC microgrid unit through a communication line respectively. 10 . Unidirectional DC/DC converter, battery management unit and bidirectional DC/DC converter in energy storage unit, said bidirectional AC/DC inverter, and PLC controller and auxiliary of power distribution cabinet in said AC microgrid unit The controllers of the electrical equipment of the air unit and the thermal management unit in the system unit are connected to the first circuit breaker and the second circuit breaker in the energy storage unit of the fuel cell test unit of the DC microgrid unit through low-voltage signal lines respectively. The voltage and current Hall sensors of the inverter and the DC bus L1, the circuit breaker in the bidirectional AC/DC inverter, the third circuit breaker of the DC microgrid unit, the voltage and current Hall sensors of the AC bus L2, and the Controller connections for common connection points in power distribution units. 10. A control method for a micro-grid system based on fuel cell testing, characterized in that the method is realized by the following steps: Step (1), the energy management unit starts a self-check, and confirms that the public connection point in the power distribution unit is in a disconnected state, so that the entire microgrid system enters the initial off-grid control mode; Step (2), the energy management unit acquires the number of fuel cells to be tested and test parameters in the fuel cell test unit of the DC microgrid unit, and determines the total electricity Q ₁ generated by the fuel cell during the entire test process, according to the AC The electrical equipment of the auxiliary system unit in the microgrid unit and the power acquisition of the sensitive load and general load in the miscellaneous load unit The total power _Q2 required by each electrical equipment of the AC microgrid unit before the fuel cell test and during the fuel cell test The required total power Q′ ₂ , the SOC of the energy storage battery group is obtained through the DC micro grid unit, and the dischargeable amount Q ₃ when the energy storage battery group is discharged from the current SOC to the set SOC lower limit and the current SOC is charged to the set value is determined. _The required charge amount Q _{′ 3} when the _SOC upper _{limit of} the If Q ₁ ≤Q′ ₂ +Q′ ₃ , and Q ₂ ≤ Q ₃ , enter the steady-state off-grid working mode; If Q ₁ >Q' ₂ +Q' ₃ , or Q ₂ >Q ₃ , enter the transient grid-connected working mode. 11 . The control method for a microgrid system based on fuel cell testing according to claim 10 , wherein the steady-state off-grid working mode is: the energy management unit firstly supplies the power to the DC microgrid unit. 12 . The bidirectional DC/DC converter of the energy storage unit and the bidirectional AC/DC inverter send a start signal, and simultaneously to the second circuit breaker of the energy storage unit in the DC microgrid unit and the bidirectional AC/DC inverter The grid-connected circuit breaker sends a closing signal to convert the DC power stored in the energy storage battery pack of the energy storage unit into a specified DC voltage via a bidirectional DC/DC converter and send it to the DC bus L1 of the DC microgrid unit, Then the bidirectional AC/DC inverter converts the DC power on the DC bus L1 into a specified AC voltage and sends it to the AC bus L2 of the AC microgrid unit; then the energy management unit sends the AC microgrid unit to the AC microgrid unit. The third circuit breaker sends a closing signal to send the AC power on the AC bus L2 into the power distribution cabinet, and at the same time sends commands to the PLC controller in the power distribution cabinet of the AC microgrid unit to distribute the power received by the power distribution cabinet. Sensitive load and general load to each electrical equipment and miscellaneous load unit in the air unit and thermal management unit of the auxiliary system unit, each electrical equipment starts to work to provide air with a specific pressure for the fuel cell to be tested and make fuel The battery rises or stabilizes to a set temperature; when the energy management unit receives a signal from the fuel cell test bench in the fuel cell test unit that the fuel cell meets the test conditions, it sends a start-up test to the fuel cell test bench Signal and close the first circuit breaker, carry out the electrochemical performance test of the fuel cell to be tested according to the preset parameters and working steps, and the generated electric energy is converted into the specified voltage by the unidirectional DC/DC converter and then sent to the DC bus L1 At this time, the energy management unit monitors the voltage fluctuations of the DC bus L1 and the AC bus L2 in real time: when the monitored voltage of the DC bus L1 and/or the AC bus L2 deviates from the set upper limit threshold of the bus balance voltage, it will give The bidirectional DC/DC converter of the energy storage unit in the DC microgrid unit sends a charging signal to charge the excess electric energy on the DC bus L1 into the energy storage battery pack, so that the voltage of the DC bus L1 and/or the AC bus L2 fall back to the set bus balance voltage; when the monitored voltage of the AC bus L2 and/or the DC bus L1 deviates from the set lower limit threshold of the bus balance voltage or the fuel cell stops the test, it will be stored in the DC microgrid unit. The bidirectional DC/DC converter of the energy unit sends a discharge signal to send the electric energy stored in the energy storage battery pack into the DC bus L1 and into the AC bus L2 via the bidirectional AC/DC inverter, so that the DC bus L1 and the AC The voltage of the bus L2 rises back to the set bus balance voltage. 12 . The control method for a microgrid system based on fuel cell testing according to claim 10 or 11 , wherein the transient grid-connected working mode is: the energy management unit firstly converts the energy storage unit The DC power stored in the energy storage battery pack is converted into a specified AC voltage after secondary inversion by the bidirectional DC/DC converter and the bidirectional AC/DC inverter, and sent to the AC bus L2 of the AC microgrid unit, and then closed. The third circuit breaker in the AC microgrid unit sends the AC power on the AC bus L2 into the power distribution cabinet, and the power distribution cabinet distributes the received power to each of the air unit and the thermal management unit of the auxiliary system unit. Sensitive load and general load of electrical equipment and miscellaneous load units, each electrical equipment starts to work to provide air with a specific pressure for the fuel cell to be tested and make the fuel cell rise or stabilize to a set temperature; the fuel cell test bench starts The electrochemical performance of the fuel cell to be tested is tested according to the preset parameters and working steps, and the generated electric energy is converted into a specified voltage by the unidirectional DC/DC converter and sent to the DC bus L1; The energy storage battery pack of the energy storage unit in the power grid unit suppresses the voltage fluctuations of the DC bus L1 and the AC bus L2 and balances the voltages of the two buses by charging and discharging according to the voltage fluctuations of the DC bus L1 and the AC bus L2; When the state of charge SOC of the battery pack has dropped to the set lower limit, the common connection point of the power distribution unit is closed to send the electric energy of the external grid into the AC bus L2 to ensure the auxiliary system unit of the AC microgrid unit. The electrical equipment of the air unit and the thermal management unit and the sensitive loads in the miscellaneous load unit work normally, and if the external power grid is in the valley power period at this time, the bidirectional AC/DC inverter will convert the AC bus L2 After the electric energy is inverted by the secondary AC-DC and DC/DC, the valley electricity of the external grid is charged into the energy storage battery pack; when the SOC of the energy storage battery pack has risen to the set upper limit, the fuel cell test is still During the process, the common connection point of the power distribution unit is closed, and the DC power generated by the fuel cell during the test is fed into the external power grid after the DC/DC and DC-AC secondary inversion.

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