JPH04304126A - Device for supplying electric power from fuel cell - Google Patents

Abstract

PURPOSE:To continuously supply electric power to a DC load and specific AC load and, at the same time, to continuously utilize the thermal energy of a fuel cell by efficiently operating the fuel cell under rated conditions even when a power failure occurs in a device for supplying electric power of fuel cell which is connected in parallel with a commercial source and supplies electric power to a plurality of DC and AC loads. CONSTITUTION:The output of a fuel cell 2 is connected in parallel with commercial power supply 1 through a DC-AC inverter 3. AC loads 51-5n and DC loads 41-4n provided with rectifiers 81-8n and batteries 91-9n are respectively connected to the connecting points of the battery 2 with the power supply 1 through switches 121-12n and a switch 101 and electric power is usually supplied to the loads from the fuel cell 2 operated under rated conditions and power source 1. When the commercial power supply 1 is failed, an inverter control circuit 31 supplies electric power to the DC loads 41-4n without hit by opening the switch 101 and specific switches 121-12n and continuously supplies electric power to the AC loads 51-5n from the fuel cell 2 operated at a rated rate.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a supply device that supplies power to multiple DC loads and multiple AC loads by interconnecting a fuel cell with a commercial power source, and in particular, operates a fuel cell at a constant output during a power outage. The present invention relates to a fuel cell power supply device that can continue to operate with high efficiency under various conditions.

0002

[Prior Art] A fuel cell is a power generation device that generates electricity by chemically reacting hydrogen obtained by reforming city gas, etc. with oxygen in the air, and using a reaction that is the reverse of the electrolysis of water. . This fuel cell has high power generation efficiency, the exhaust gas associated with the reaction is clean and low pollution, and the heat generated through the reaction can be used for air conditioning, hot water heating, etc., making it a clean and highly efficient next generation. In recent years, it has been attracting attention as a cogeneration system. By the way, when building a system that uses fuel cells as an energy source and uses both electrical output and thermal output, if the electrical output fluctuates, the heat capacity that can be taken out changes and the necessary thermal energy cannot be obtained, or the There is a drawback that if the operation continues in the output state, the power generation efficiency will decrease. Therefore, in general, it is most efficient to always use the rated output of the fuel cell. Conventionally, the output of a fuel cell is converted to alternating current, and the output voltage, frequency, and phase of the commercial power source are made equal to each other, and the respective outputs are connected in parallel. The point is ``
A system configuration was adopted in which power was supplied through the network (called a "connection point"). As a result, fluctuations in power were supplied from the commercial power source, and constant power was supplied from the fuel cell.

FIG. 3 shows the system configuration of the conventional fuel cell power supply device. In the figure, 1 is a commercial power supply, 2 is a fuel cell, and 3 is a DC-A that converts DC power to AC power.
C inverter, 41 to 4n are DC loads, 51 to 5n are AC loads, 6 and 7 are switches, 81 to 8n are rectifiers, 9
1 to 9n are storage batteries, 11 is a commercial synchronization signal detection section, 21 is a power detection section, and 31 is a DC-AC inverter control section having an arithmetic function. In the conventional fuel cell supply device, a DC-AC inverter 3 and a switch 7 are connected in series to the output of the fuel cell 2 via an output power detection section 21 . In addition, a switch 6 is connected in series to the output of the commercial power supply 1 via the commercial synchronization signal detection unit 11, and the output of the switch 6 and the output of the interconnection point of the switch 7 are connected to the DC load via the rectifiers 81 to 8n. 41 to 4n are connected, and a backup storage battery 91 is connected between each rectifier 81 to 8n and each DC load 41 to 4n.
~9n are connected respectively. In addition, the rectifier 8
AC loads 51-5n are connected in parallel with 1-8n. The switches 6 and 7 also have a breaker function when the fuel cell 1, DC-AC inverter fails, or AC load fails. Further, the commercial synchronization signal detection section 11, the power detection section 21, and the cutoff signal detection lines of the switches 6 and 7 are connected to the DC-AC inverter control section 31.

[0004] In a fuel cell power supply device having such a system configuration, a method of interconnecting a commercial power source and a private power generating device such as a fuel cell is to supply constant power from the fuel cell and supply variable load from the commercial power source. A base-cut power supply method is used, and a peak-cut method, which is the opposite of this method, is used to supply power. However, in general, when interconnecting a fuel cell and a commercial power source, the fuel cell output capacity is smaller than the load capacity, and a base cut power supply method is used from the viewpoint of load fluctuation characteristics. Therefore, the case where the device is configured with a circuit to which the base-cut power feeding method is applied will be described here as well.

FIG. 4 is an operational mode diagram of the conventional fuel cell power supply device. In the figure, the horizontal axis represents time and the vertical axis represents electric energy. In the figure, (1) shows the output power amount of the commercial power source 1, and (2) shows the input power amount of the fuel cell 2 on the DC-AC inverter side. The operation mode of this fuel cell power supply device is such that the DC-AC inverter 3 and the commercial power supply 1 supply the necessary power to the DC loads 41 to 4n and AC loads 51 to 5n connected to the switches 6 and 7. supply In such power supply, the DC-AC inverter 3 detects a commercial synchronizing signal from the commercial synchronizing signal detection unit 11 and is constantly operated in a connected manner.For example, when the AC loads 51 to 5n increase, As shown in (1) of 4, the output power of the commercial power source 1 increases, and the output power of the fuel cell 2 is kept constant. That is, the output power of the fuel cell 2 is sent to the inverter control section 31 according to the signal detected by the power detection section 21, and the inverter control section 31 detects the output power of the fuel cell 2 as shown in (2) in FIG. The DC-AC inverter 3 is controlled to always maintain a constant output state. Conversely, even when the AC loads 51 to 5n decrease, the output of the commercial power source 1 decreases, and the output power of the fuel cell 2 is always kept constant.

[0006]

[Problems to be Solved by the Invention] However, in the fuel cell power supply device according to the above-mentioned conventional technology, the commercial power supply 1
If there is a power outage, the output capacity of the fuel cell 2 is smaller than the load capacity as described above, so the output of the fuel cell 2 is instantaneously reduced to the DC load 41 to 4n through all the rectifiers 81 to 8n.
In addition, power is supplied to the AC loads 51 to 5n, and the fuel cell 2 becomes overloaded, which may lead to device failure in the worst case. Therefore, when a power outage signal is detected, the switch 6
7 was opened, and power supply to all loads had to be stopped in the event of a power outage of the commercial power supply 1. In other words, the conventional fuel cell power supply device consists of a commercial power source 1 and a fuel cell 2.
The output voltage of the output via the DC-AC inverter 3 from
Power is supplied to the loads by connecting them in parallel with the same frequency and phase, but if the commercial power supply 1 has a power outage, not only will it be impossible to supply power to the loads 41 to 4n and 51 to 5n, but thermal energy will also be lost. The disadvantage was that the supply of

The present invention was devised to improve these drawbacks, and its purpose is to enable fuel cells to continue operating at their rated output even during a commercial power outage, and to It is an object of the present invention to provide a fuel cell power supply device that can continuously supply power to a load system and a specific AC load, and can also continue to supply thermal energy from a fuel cell without interruption.

[0008]

[Means for Solving the Problems] In order to achieve the above object, in the fuel cell power supply device of the present invention, a DC-AC inverter is connected in series to the output of the fuel cell, and the
A DC load system comprising a commercial power supply connected in parallel to the output of a C-AC inverter, a rectifier connected to the parallel connection output, a storage battery floatingly charged from the rectifier output, and a DC load supplied with power from the rectifier and the storage battery. A plurality of AC loads are each connected in parallel, and the output capacity of the fuel cell is smaller than the capacity of the plurality of DC load systems and the plurality of AC loads, and the output of the fuel cell is smaller than the capacity of the plurality of DC loads and the plurality of AC loads. In a fuel cell power supply device configured to send out a constant output regardless of fluctuations in AC load, a first switch is connected in series with the output of the commercial power source, and a second switch is connected in series with the output of the DC-AC inverter. a third switch is connected in series between the connection point of the DC-AC inverter and the commercial power supply connected in parallel and the plurality of rectifiers, and a third switch is connected in series between the connection point and the plurality of rectifiers, and A fourth switch is connected in series between the plurality of AC loads, so that the output voltage, frequency and phase of the DC-AC inverter are always equal to those of the commercial power supply, and the output voltage, frequency and phase of the DC-AC inverter are always made equal to those of the commercial power supply, and Electric power is supplied to an AC load from the fuel cell output and the commercial power supply, and when the commercial power supply fails, the first switch and the third switch are all opened instantly, and at the same time, the power is supplied to the plurality of AC loads. If the sum of the electric power supplied before generation is greater than the preset output capacity of the fuel cell, the fourth The present invention is characterized by comprising a control unit that opens a plurality of switches according to a predetermined priority order to continue supplying power to a specific AC load among the plurality of AC loads without momentary interruption.

[0009]

[Operation] In the fuel cell power supply device of the present invention, in the event of a commercial power outage, the DC load system equipped with a rectifier and a backup storage battery in case of a power outage is disconnected from the system without momentary interruption, and power is supplied to the DC load from the backup storage battery. , the fuel cell continues to supply power without interruption to an AC load equivalent to the fuel cell's rated output power. In this way, by continuing the rated output operation of the fuel cell even during a commercial power outage, it is possible to continue supplying thermal energy and improve power generation efficiency and utilization rate of thermal energy.

0010

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention. In the figure, 1 is a commercial power source, 2 is a fuel cell, 3 is a DC-AC inverter that converts DC power to AC power, 41 to
4n is a DC load, 51 to 5n are AC loads, 6 and 7 are switches, 81 to 8n are rectifiers, 91 to 9n are storage batteries, 1
01,121-12n are switches, 111,131-1
3n is an AC output detection section, 11 is a commercial synchronization signal detection section, 2
Reference numeral 1 represents a power detection unit, and 31 represents a DC-AC inverter control circuit having an arithmetic function. Among the above-mentioned constituent parts, the parts which are common to the constituent parts of FIG. 3 described in the related art are given the same numbers. However, as described later, the DC-AC inverter control circuit 31 has a control function when a power outage is detected, including a function to make the DC-AC inverter 3 independent and continue operation at a constant output, and a function to instantly turn on the switch 6 and the switch 101. At the same time, if the sum of the power supplied to the plurality of AC loads 51 to 5n before the power outage is greater than the preset output capacity of the fuel cell 2, the sum of the power and the preset output capacity of the fuel cell 2 A function is added to open the plurality of switches 121 to 12n in accordance with a predetermined priority order according to a set difference in output capacitance.

In the configuration of this embodiment, a DC-AC inverter 3 is connected to the output of the fuel cell 2, and a switch 7 is connected to the output of the DC-AC inverter 3. In addition, a switch 6 is connected to the output of the commercial power supply 1 via a commercial synchronization signal detection unit 11.
are connected in series, and DC loads 41-4n are connected from the output of switch 6 and the interconnection point of switch 7 via AC output detection section 111, switch 101 and rectifiers 81-8n, and AC output detection sections 131-4n are connected in series. 13n, switch 121
AC loads 51 to 5n are connected through 12n. Additionally, storage batteries 91 to 8 are used as backup power sources in the event of an AC power outage between the rectifiers 81 to 8n and the DC loads 41 to 4n.
9n is connected. A power detection section 21 is connected to the input of the DC-AC inverter 3, and a signal line is connected to an inverter control circuit 31 having an arithmetic function. The inverter control circuit 31 is connected to a signal line of a commercial synchronization signal detection unit 11 to obtain a synchronization signal of the commercial power supply 1, and an AC output detection unit 111 that detects the power of the DC loads 41 to 4n and each AC load 51 to 5n. , 131 to 13n are connected to the signal lines.

The operation and effect of one embodiment configured as above will be described.

FIG. 2 is an operation mode diagram for explaining the operation of the above embodiment. In the figure, the horizontal axis represents time and the vertical axis represents electric energy. In the figure, (1) is the output power amount of the commercial power supply 1, and (2) is the DC-AC inverter 3 of the fuel cell 2.
This is the input power amount on the side, and is detected by the power detection unit 21. (2)' is the DC- of the fuel cell 2 supplied during a power outage.
This is the input power amount on the AC inverter 3 side, and the AC load 51
~5n. First, the operation of this embodiment will be explained based on FIGS. 1 and 2.

Power is normally supplied from the fuel cell 2 and the commercial power supply 1 to the DC loads 41 to 4n and the AC loads 51 to 5n. At this time, the amount of output power from the fuel cell 2 is detected by the power detection unit 21 provided on the input side of the DC-AC inverter 3, and the signal is sent to the inverter control circuit 31 that has a calculation function. . DC-A
The C inverter 3 is always operated in synchronization with the commercial power supply 1 by an inverter control circuit 31 that receives a signal from the commercial synchronization signal detection section 11. In this state, the switches 101 for the DC loads 41 to 4n and the switches 101 for the AC loads 51 to 5n
All of the n switches 121 to 12n are closed. As shown in FIG. 2, the AC loads 51 to 5n change over time. For example, when the amount of power used by the AC loads 51 to 5n increases, the output power of the commercial power supply 1 increases, and the AC output detection units 131 to 13n A signal is sent to an inverter control circuit 31 equipped with arithmetic functions. The inverter control circuit 31 controls the DC-AC inverter 3 so that the output power of the fuel cell 2 always maintains a constant output state. AC load 5
Even when the used power of 1 to 5n decreases, the output of the commercial power source 1 decreases and the output power of the fuel cell 2 is kept constant.

Next, the operation when the commercial power supply 1 is out of power will be described. A power outage of the commercial power supply 1 is detected by the inverter control circuit 31 through the commercial synchronization signal detection section 11, for example. Here, the inverter control circuit 31 includes the switch 6 and backup storage batteries 91 .
Input switch 1 of DC loads 41 to 41n having n
Instantly release all 01. At the same time, the DC-AC inverter 3, which normally operates in synchronization with the commercial power source 1, is allowed to continue operating independently at the same time as the power outage. In addition, the inverter control circuit 31 having an arithmetic function detects the amount of power of the AC loads 51 to 5n immediately before the commercial power supply 1 loses power to the detection unit 1.
31 to 13n signals. As a result, the inverter control circuit 31 uses the output power of the fuel cell 2 and the AC load 5.
1 to 5n, and if it is greater than the preset output power of the fuel cell 2, the less important AC load 5
Any one of the switches 121 to 12n of switches 1 to 5n is opened instantly. As described above, the output power of the fuel cell 2 operates to continue constant output operation. These calculations are performed by the inverter control circuit 31. Thereafter, the inverter control circuit 31 constantly monitors the amount of power used by the AC load,
Control is performed so that the output of the fuel cell 2 is always maintained at a set constant output operation. In addition, in the above, switch 6
, 7 and 101, 121 to 12n also have the function of a circuit breaker that promptly shuts off the circuit in the event of a device failure or an abnormality in the commercial power supply.

As described above, in this embodiment, the rated operating state of the fuel cell can be continued even if the commercial power supply 1 is out of power. Further, it is possible to continue supplying power to both the DC loads 41 to 4n and the specific AC loads 51 to 5n, and it is also possible to continuously supply stable thermal energy. That is, an operation can be performed in which the electrical energy and thermal energy of the fuel cell 2 can be used efficiently. In addition, fuel cell 2
Since it is always operated at the rated value regardless of load fluctuations or power outages of the commercial power supply 1, it is possible to operate with the highest power generation efficiency.

[0018]

Effects of the Invention As is clear from the above explanation, the fuel cell power supply device of the present invention connects the output from the fuel cell via the DC-AC inverter and the output of the commercial power source, and connects the output of the commercial power source to the rectifier. When supplying power to multiple DC loads and multiple AC loads through a power supply, if the commercial power supply fails,
The switch on the output side of the commercial power supply and the switch on the input side of the DC load with a backup storage battery are opened without momentary interruption, and power is continuously supplied from the fuel cell to the AC load that corresponds to the rated output of the fuel cell. As a result, the fuel cell can always maintain the most efficient rated output operation, and has the advantage of stable use of thermal energy and highly efficient power supply.

[Brief explanation of drawings]

[Fig. 1] A configuration diagram showing an embodiment of the present invention.

[Fig. 2] Operation mode diagram for explaining the operation of the above embodiment.

[Figure 3] Configuration diagram showing a conventional example

[Figure 4] Operation mode diagram of the above conventional example

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Commercial power supply, 2... Fuel cell, 3... DC-AC inverter, 6, 7... Switch, 11... Commercial synchronization signal detection part, 2
1...Power detection unit, 31...Inverter control circuit, 41-4
n... DC load, 51-5n... AC load, 81-8n... Rectifier, 91-9n... Storage battery, 101... Switch, 11
1...AC output detection section, 121-12n...switch, 13
1 to 13n...AC output detection section.

Claims (1)

[Claims] Claim 1: A DC-AC inverter is connected in series to the output of a fuel cell, a commercial power source is connected in parallel to the output of the DC-AC inverter, a rectifier is connected to the parallel-connected output, and a floating charge is applied from the rectifier output. A plurality of DC load systems each consisting of a storage battery, a rectifier, and a DC load supplied with power from the storage battery and an AC load are connected in parallel, and the output capacity of the fuel cell is equal to the output capacity of the plurality of DC load systems and the plurality of AC loads. In the fuel cell power supply device, the fuel cell has a capacity smaller than that of the commercial power supply, and is configured such that the output of the fuel cell is a constant output regardless of fluctuations in the plurality of DC loads and the plurality of AC loads. A first switch is connected in series, a second switch is connected in series to the output of the DC-AC inverter, and the D
A third switch is connected in series between the connection point of the C-AC inverter and the commercial power supply connected in parallel and the plurality of rectifiers, and a third switch is connected in series between the connection point and the plurality of AC loads. A fourth switch is connected to each of the DC-AC inverters so that the output voltage, frequency and phase of the DC-AC inverter are always equal to the commercial power supply, and the fuel cell output is connected to the plurality of DC loads and the plurality of AC loads. Electric power is supplied from the commercial power source, and when the commercial power source experiences a power outage, the first switch and the third switch are all opened instantly, and at the same time, the power that was being supplied to the plurality of AC loads before the power outage occurs. is greater than the preset output capacity of the fuel cell, the fourth plurality of switches are given a predetermined priority according to the difference between the sum of the electric powers and the preset output capacity of the fuel cell. 1. A fuel cell power supply device, comprising: a control unit that opens the AC loads in accordance with the order of the AC loads and continues supplying power to a specific AC load among the plurality of AC loads without momentary interruption.