JP2001327100A - Power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply an independent load with a high quality uninterruptible power having arranged voltage and frequency, while realizing 100% facility utilization rate for a fuel cell power generation system, even during variation of the independent load. SOLUTION: The power supply system comprises a fuel cell power generation system, connected with a DC bus and having a fuel cell outputting a DC power where a plurality of unit cells generating power through reaction of fuel gas and oxidizing agent gas are connected, and a plurality of inverters connected with the DC bus and converting DC power into AC power being supplied to an independent load. At least one inverter has an interlinking operation function with an AC system for supplying excessive power to a commercial system, i.e., the AC system, while preferentially supplying power to the independent load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply system using a fuel cell power generation system for generating power by an electrochemical reaction between a fuel gas and an oxidizing gas, and more particularly to a power supply system using a fuel cell power generation system even when a single load changes. Equipment utilization rate of 100
The present invention relates to a power supply system capable of supplying high-quality, uninterruptible power with a uniform voltage and frequency to a single load while realizing a single load.

[0002]

2. Description of the Related Art In general, a fuel cell power generation system uses, for example, phosphoric acid as an electrolyte and converts a fuel gas obtained by reforming a raw fuel such as natural gas and an oxidizing gas such as oxygen in the air. Direct power generation is performed by chemical reaction, and high power generation efficiency can be obtained.

[0003] Moreover, this fuel cell power generation system has been evaluated as a power generation system with extremely low environmental pollutants and low noise, which is extremely environmentally friendly.

[0004] Conventionally, a fuel cell power generation system has a fuel cell power generation system (referred to as a fuel cell power generation system) that connects a plurality of cells that generate electric power by an electrochemical reaction between a fuel gas and an oxidizing gas and that outputs DC power. Hereinafter, referred to as a fuel cell body) and an inverter for converting DC power from the fuel cell body to AC power, and the AC power output is AC power generated from the inverter. Therefore, high-quality electric power having a uniform voltage and frequency can be supplied.

[0005] Therefore, recently, a power supply system using a fuel cell power generation system with high efficiency and excellent environmental performance has been replaced with a conventional uninterruptible power supply system (generally referred to as a CVCF device or a UPS device). Attempts have been made to use it.

FIG. 2 is a schematic diagram showing an example of a power supply system using a conventional fuel cell power generation system intended to be used as an alternative to this type of uninterruptible power supply system.

[0007] The present power supply unit is always connected to the AC system, and while operating at 100% in order to maximize the efficiency and excellent environmental performance, the power supply unit can be operated with a single load even during a power outage. It is intended to supply electric power.

That is, as shown in FIG. 2, the fuel cell main body 1 is formed by connecting a plurality of cells which generate electric power by an electrochemical reaction between a fuel gas and an oxidizing gas in series, and outputs DC power. I do.

The DC power generated from the fuel cell main body 1 is converted into AC power by an inverse converter 2 and
To the single load 4 and further to the AC system 6 via the switch 5.

In the power supply system using the fuel cell power generation system configured as described above, the fuel cell power generation system supplies power to the single load 4 by closing both the switch 3 and the switch 5. While AC system 6
Connected operation with.

When an abnormality occurs in the AC system 6 in this state, the switch 5 is opened to shift to the independent operation of the fuel cell main body 1, and when the fuel cell main body 1 cannot generate power due to a failure or the like. On the contrary, the switch 3 is opened to disconnect the fuel cell main body 1, and the electric power is continuously supplied from the AC system 6 to the single load 4.

FIG. 3 is a schematic configuration diagram showing another example of a power supply system using a conventional fuel cell power generation system intended to be used as a substitute for an uninterruptible power supply system. Are denoted by the same reference numerals and description thereof is omitted, and only different portions will be described here.

The power supply system is used as a power source for a device such as a computer or a medical device that does not allow disturbance from a commercial AC system.・ It is intended to perform isolated operation with stable frequency.

That is, as shown in FIG. 3, the switch 3 and the switch 5 in FIG. 2 are omitted, and a switch 7 using a semiconductor is used instead of the switch 3 and is always connected to the fuel cell main body 1 side. Then, the isolated operation is performed, and only when an abnormality such as a failure of the fuel cell body 1 occurs, the switch is switched to the AC system 6 side by the changeover switch 7 to supply power from the AC system 6 to the independent load 4.

[0015]

However, the power supply system using the fuel cell power generation system configured as described above has the following problems.

That is, in the case of the power supply device shown in FIG. 2, the utilization factor of the fuel cell main body 1 can be achieved at 100%, and the high efficiency and excellent environmental performance inherent in the fuel cell power generation system can be maximized. Although it can be demonstrated to the maximum extent, it is possible to receive disturbance from the AC system 6 since the interconnection operation with the AC system 6 is fundamental, and it is not possible to obtain the same power supply quality as the existing CVCF device. .

In the case of the power supply device as shown in FIG. 3, since the fuel cell body 1 is basically operated independently, the power supply quality can be equivalent to that of the existing CVCF device. In addition, only the partial load operation accompanying the fluctuation of the single load 4 can be performed, and the high efficiency and the excellent environmental performance, which are the inherent features of the fuel cell power generation system, cannot be maximized.

It is an object of the present invention to provide a method for controlling a single load even when the load varies.
It is an object of the present invention to provide a power supply system capable of supplying high-quality and uninterrupted power having a uniform voltage and frequency to a single load while realizing a 100% utilization factor of a fuel cell power generation system.

[0019]

In order to achieve the above object, according to the first aspect of the present invention, a plurality of unit cells for generating electricity by an electrochemical reaction between a fuel gas and an oxidizing gas are connected. A fuel cell power generation system that has a fuel cell that outputs DC power and is connected to a DC bus, and a plurality of inverters that are connected to the DC bus and convert DC power to AC power and supply it to a single load. And at least one of the inverters is connected to the AC system so as to supply surplus power to the AC system as a commercial system while giving priority to power supply to a single load. Shall be provided.

Therefore, in the power supply system according to the first aspect of the present invention, since a part of the plurality of inverters performs the single load operation without being connected to the AC system, a specific single inverter is operated. High quality power can be supplied to the load.

On the other hand, at least one or more of the remaining inverters perform the interconnection operation with the AC system, thereby absorbing the fluctuation of the single load as the power supply to the AC system, and constantly supplying high-quality power. While giving priority to the operation, the fuel cell power generation system can achieve a capacity factor of 100%.

In addition, if the capacity of the inverter for the system interconnection can convert 100% of the DC output of the fuel cell power generation system in total, even if the single load becomes no load, 100% operation can be performed.

According to the second aspect of the present invention, the first aspect is provided.
In the power supply system of the invention, the power supply system is connected to a DC bus,
At least one DC / DC converter for converting DC power into a constant DC voltage / current and supplying the DC power to a single DC load is added.

Therefore, in the power supply system according to the second aspect of the present invention, in addition to the first aspect of the present invention, the DC output of the fuel cell power generation system that changes every moment is at least one.
The DC / DC converters can supply high-quality DC power of a constant DC voltage and current to a single DC load.

According to a third aspect of the present invention, in the power supply system according to the second aspect of the present invention, at least one forward conversion device connected to the DC bus and converting AC power to DC power is added. When the DC output of the battery power generation system becomes smaller than the capacity of the single load, the AC power from the AC system is converted to DC power by the forward converter and added to the DC output of the fuel cell power generation system to the single load. To supply.

Therefore, in the power supply system according to the third aspect of the present invention, in addition to the second aspect of the invention, at least one forward conversion device for converting AC power to DC power is provided, so that the fuel cell power generation system is provided. Even if the DC output of the fuel cell power generation system becomes smaller than the capacity of the single load due to failure or inspection of the power supply, the power supply is reversed from the AC system to supply high-quality power to the single load. Furthermore, uninterrupted power can be provided.

[0027] According to the invention of claim 4, the above-mentioned claim 3 is provided.
In the power supply system according to the invention, DC power supply equipment such as a solar cell and a battery connected to the DC bus so as to be connected to the fuel cell power generation system and outputting DC power is added.

Therefore, in the power supply system according to the fourth aspect of the present invention, in addition to the third aspect of the present invention, a DC power supply system such as a solar cell or a battery and a fuel cell power generation system are interconnected by DC. An uninterruptible DC bus can be formed, and supply of high-quality power to a single load can be further uninterrupted.

According to a fifth aspect of the present invention, in the power supply system according to the fourth aspect of the present invention, the AC power from each of the inverters and the AC power from the AC system are separately input, and normally the reverse power is supplied. A changeover switch is provided for switching so as to supply AC power from the converter and AC power from the AC system to a single load in the event of an abnormality such as a failure of the inverter.

Therefore, in the power supply system according to the fifth aspect of the present invention, in addition to the fourth aspect of the present invention, the AC power from the independent load inverter and the AC power from the AC system for supplying high-quality power are provided. By switching between the power and the switching switch at a high speed, in the event of an abnormality such as a failure of the inverter, it is possible to back up with power supplied by the AC power from the AC system, and the failure of the inverter for a single load, etc. By supplying power even in the event of an abnormality, a complete uninterruptible power supply can be realized.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an example of a power supply system using the fuel cell power generation system according to the present embodiment.

In FIG. 1, a fuel cell body 11 which connects a plurality of cells in series or in series and in parallel to output DC power, a solar cell 12 which outputs DC power,
DC power supply equipment such as a rechargeable battery 13 is connected to the DC bus 14 to form a DC power generation system.

On the other hand, the DC bus 14 is connected to a plurality of inverters 15 dedicated to independent operation for converting DC power into AC power and supplying high-quality power to a single load (not shown).

The AC bus 16 is connected to the DC bus 14 so that excess power is supplied to the AC system 16 which is a commercial system while giving priority to power supply to a single load (not shown).
Forward / reverse converter 1 for system interconnection with interconnection operation function
7 is connected.

That is, the forward / reverse conversion device 17 for system interconnection
Is normal, that is, when the DC output (total generated power amount) of the entire DC power generation system with the fuel cell main body 11 as a core exceeds the capacity of a single load directly connected,
When the surplus AC power is supplied to the AC system 16 and the DC output (total power generation) of the entire DC power generation system is less than the capacity of the directly connected single load, the device functions as a forward conversion device. Then, the AC power from the AC system 16 is converted into DC power, and is supplied to a single load in addition to the DC output (total generated power amount) of the DC power generation system.

Further, the DC bus 14 is connected to at least one DC / DC converter 18 for converting DC power into a constant DC voltage / current and supplying the DC power to a single DC load (not shown). .

Further, the AC power from each of the inverters 15 and the AC power from the AC system 16 are separately input to the output side of each of the inverters 15, and switching is performed to switch between them. A switch 19 is provided.

That is, the changeover switch 19 normally supplies the AC power from the inverter 15 and, in the event of an abnormality such as a failure of the inverter 15, the AC power from the AC system 16 as a single load for backup. The switching is performed at a high speed so that the power is supplied to the power supply.

Next, the operation of the power supply system according to the present embodiment configured as described above will be described.

In FIG. 1, a fuel cell main body 11, a solar cell 12, and a battery 13 output DC power to a DC bus 14, respectively.

That is, the entire DC power generation system with the fuel cell main body 11 as the core always performs a re-high output operation as much as possible so as to maximize its features such as high efficiency and environmental performance. .

On the other hand, each inverter 15 is provided with an AC system 16
, Performs independent operation completely independently, and supplies high-quality AC power with regulated voltage and frequency to single loads (important loads) such as computers and medical equipment.

For a DC-only load requiring a constant DC power with a constant voltage and current, the DC / DC converter 18
To supply high quality DC power.

However, since these single loads are not always constant and change every moment, there is a possibility that the total amount of generated power of the entire DC power generation system becomes excessive or insufficient in some cases. There is.

Therefore, the surplus / deficiency of the electric power is continuously adjusted by the grid connection forward / inverting device 17 connected to the AC system 16 so that the generated output (generated power) is maximized. Keep constant.

The forward / reverse converter 17 for the system interconnection
Is to keep the supply of the required high-quality power even when the DC power generation system including the fuel cell body 11 has an abnormality by setting the capacity to be equal to or larger than the capacity of the connected single load. Can be.

That is, the forward / reverse conversion device 17 for system interconnection
Also plays a role in further converting this high-quality power supply into an uninterruptible power supply.

However, when the inverter 15 for supplying high-quality power fails, the uninterruptible operation for the single load cannot be achieved.

Therefore, in such a case, the switching power supply 19 provided on the output side of the inverter 15 supplies the AC power from the AC system 16 to the single load as a backup.

As described above, the power supply system according to the present embodiment can provide the following various effects.

(A) Since the inverter 15 performs single-load operation without being connected to the AC system 16, high-quality electric power can be supplied to a specific single load. Further, the forward / reverse conversion device 17 for system interconnection performs the interconnection operation with the AC system 16 so as to absorb the fluctuation of the single load as the electric power supply to the AC system 16, and always perform the high-quality electric power supply operation. , The fuel cell power generation system can achieve a facility utilization of 100%. Further, the forward / reverse conversion device 17 for system interconnection
If the total capacity can convert 100% of the DC output of the fuel cell main body 11, continuous 100% operation can be performed even when the single load becomes no load.

In other words, high-quality AC power and high-quality DC power, which are completely independent of the AC system 16 and whose voltage and frequency are adjusted, can be supplied to a single load such as a computer or medical equipment. In order to maximize the high efficiency, energy saving, and excellent environmental performance inherent in the fuel cell power generation system, it is possible to perform as large an output operation as possible at that time.

(B) The DC output of the fuel cell power generation system, which changes every moment, is supplied to a single DC load by the DC / DC converter 18 as high-quality DC power so as to have a constant DC voltage and current. Becomes possible.

(C) By providing the forward / reverse converter 17 for system interconnection, the DC output of the fuel cell main body 11 becomes smaller than the capacity of the single load due to failure or inspection of the fuel cell main body 11. Also in this case, the supply of power from the AC system 16 is reversed, and the supply of high-quality power to a single load can be further uninterrupted.

(D) Since uninterruptible DC buses can be formed by connecting DC power supply equipment such as the solar cell 12 and the battery 13 and the fuel cell body 11 with DC, a single load of high-quality power can be obtained. Supply to the power supply can be further reduced.

(E) By switching the AC power from the independent load inverter 15 for supplying high-quality power and the AC power from the AC system 16 at high speed with the switch 19, the inverter 15 is switched. In the event of a failure such as a failure, power can be backed up by the supply of AC power from the AC system 16, so that power is also supplied to a failure such as the failure of the inverter 15 for a single load and complete It is possible to realize an uninterruptible power supply.

That is, the DC bus 14 and the high-quality AC power supply line become a dual system of the power generation output and the AC system 16, so that the uninterruptible power supply can be achieved.

As described above, it is possible to obtain an extremely excellent fuel cell power generation system capable of operating the fuel cell power generation system at the maximum possible output and supplying high-quality and uninterrupted power to a single load. .

(Other Embodiments) (a) In the above-described embodiment, a case has been described in which the solar cell 12 and the battery 13 are provided as DC power supply equipment for outputting DC power. However, the present invention is not limited to this. Other means may be provided as DC power supply equipment for outputting power.

(B) In the above embodiment, the AC system 16
As means for performing the interconnection operation with the system, a forward / inverting device 17 for system interconnection is provided, and the DC output (total power generation amount) of the entire DC power generation system with the fuel cell main body 11 at the core and the load of the single load A case has been described in which the forward / reverse converter 17 for system interconnection is caused to function as a forward converter or an inverse converter based on the magnitude relationship with the capacity. However, the present invention is not limited to this.
A forward conversion device and an inverse conversion device may be provided.

[0062]

As described above, according to the power supply system of the present invention, even when a single load fluctuates, a high quality battery with a uniform voltage and frequency can be achieved while achieving a 100% utilization factor of the fuel cell power generation system. In addition, it is possible to supply uninterrupted power to a single load.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a power supply system according to the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a conventional power supply system.

FIG. 3 is a schematic configuration diagram showing another example of a conventional power supply system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Fuel cell main body, 12 ... Solar cell, 13 ... Battery, 14 ... DC bus, 15 ... Inverter, 16 ... AC system, 17 ... Forward / reverse converter for system interconnection, 18 ... DC / DC converter , 19 ... Changeover switch.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiyuki Ito 1-5-20 Kaigan, Minato-ku, Tokyo Inside Tokyo Gas Co., Ltd. (72) Inventor Naoaki Ishikawa 1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas Inside (72) Inventor Masanori Kuki 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Inside Osaka Gas Co., Ltd. (72) Inventor Naoki Kanie 2-4, Suehirocho, Tsurumi-ku, Yokohama, Kanagawa In the Toshiba Keihin Plant (72) Inventor Masanori Yabuki 1-1-1 Shibaura, Minato-ku, Tokyo F-term in the head office of Toshiba Corporation (reference) 5G015 GA08 JA10 JA24 JA53 JA64 5G066 CA09 DA08 HB06 HB07 HB09 JB03 5H420 BB14 CC03 CC06 DD03 EA47 EB37 EB39

Claims (5)

[Claims] 1. A fuel cell system comprising: a plurality of unit cells for generating power by an electrochemical reaction between a fuel gas and an oxidizing gas; and a fuel cell for outputting DC power, the fuel cell being connected to a DC bus. And a plurality of inverters connected to the DC bus and converting DC power to AC power and supplying the AC power to a single load, wherein at least one of the inverters is the single load. A power supply system having an interconnection operation function with the AC system so as to supply surplus power to an AC system which is a commercial system while giving priority to power supply to the AC system. 2. The power supply system according to claim 1, wherein said power supply system is connected to said DC bus and converts DC power to a constant DC voltage
A power supply system characterized by adding at least one DC / DC converter for converting a current to a current and supplying it to a single DC load. 3. The power supply system according to claim 2, further comprising at least one forward conversion device connected to the DC bus and converting AC power to DC power. When the output is smaller than the capacity of the single load, the AC power from the AC system is converted to DC power by the forward converter and is supplied to the single load in addition to the DC output of the fuel cell power generation system. A power supply system characterized in that: 4. The power supply system according to claim 3, wherein DC power supply equipment such as a solar cell or a battery connected to the DC bus so as to be connected to the fuel cell power generation system and outputting DC power is provided. A power supply system characterized by being added. 5. The power supply system according to claim 4, wherein the AC power from each of the inverters and the AC power from the AC system are individually input, and the power from the inverter is normally input. A power supply system characterized by further comprising a changeover switch for performing switching so as to supply AC power and AC power from the AC system to the single load when an abnormality such as a failure of the inverter occurs.