JPH08315842A - Operation method of fuel cell power generation device and auxiliary machine power supply circuit - Google Patents

Abstract

PURPOSE: To provide an operation method of a fuel cell power generation device and an auxiliary machine power supply circuit by which electric power can be supplied to an auxiliary machine without causing instantaneous interruption even when operation modes are switched to/from each other besides simplification of the circuit. CONSTITUTION: In a fuel cell power generation device to supply electric power to an electric power system by converting output of a fuel cell 2 into an alternating current by an inverter 6, an auxiliary machine power supply circuit 13 leading to an auxiliary machine 4 is connected by branching off from a power transmission circuit 12 to connect the inverter and the electric power system to each other, and a linking switch S1 is connected to the inverter side, and a linking switch S2 is connected to the electric power system side by sandwiching a branch point P of the auxiliary machine power supply circuit. ON/OFF control is selectively performed on these linking switches according to respective operation modes of 'starting', 'standby operation', 'linking operation' and 'stopping operation' of a fuel cell power generation plant, and electric power is supplied to the auxiliary machine while operating the inverter in a linking state with the electric power system in respective operation modes of a starting time 'power generation-temperature rise' step and a stopping operation time 'power generation-temperature drop' step including the 'linking operation'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a fuel cell power generator for converting a DC output of a fuel cell into AC power by an inverter and supplying the power to an electric power system, and an auxiliary power supply circuit.

[0002]

2. Description of the Related Art First, FIGS. 2A and 2B are time charts showing a conventional power supply circuit between a fuel cell power generation plant and a power system and an operating method thereof. In the figure (a), 1 is a fuel cell power plant including a fuel cell 2, a reformer 3, an auxiliary machine 4, and a dummy load 5, 6 is an inverter, and 7
Is a power system, 8 is a system power supply, and 9 is a system load. Here, interconnection switches S1 and S2 are connected in series to a transmission circuit between the inverter 6 and the electricity system 7, and interconnection switches S1 and Between the inverter 6 and the interconnection switch S
Power supply changeover switches S3 and S4 are connected to auxiliary machine power supply circuits 10 and 11 branched from 1 and S2, respectively.

The operating state of such a fuel cell power generator is as shown in FIG. 2 (b). As is well known, the operating mode of the fuel cell power generator is "start",
There are "standby operation", "coordinated operation", and "stop operation" states. Furthermore, "start" is divided into "reforming temperature increase" and "power generation temperature increase" steps, and "stop operation" is "power generation temperature decrease". , And “stop” steps.

Here, in the "reforming temperature raising" step of "starting", the fuel is introduced into the reforming catalyst in a state where the raw fuel is burned by the burner of the reformer 3, and the reforming generated here is performed. This is a process in which the gas bypasses the fuel cell 2 and is directly supplied to the reformer burner to be burned to raise the temperature of the reforming system until the reformed gas has a predetermined stable composition. This is a stop, and the linkage switch S2 and the power supply changeover switch S4 are turned on to supply the power of the auxiliary equipment 4 in the power generation plant with the electric power received from the electric power system 7. In this state, the power supply to the auxiliary equipment 4 is changed from the power system 7 to the interconnection switch S2 →
This is done by the route that passes through the power supply changeover switch S4.

On the other hand, the "power generation temperature raising" step is
This is a process in which the reaction gas of fuel and air is supplied to the fuel cell 2 to generate electric power to raise the temperature of the battery and the auxiliary equipment. In this step, the power supply switch S3 is turned on and the power supply changeover switch S4 is turned off, and the inverter 6 Is operated independently to supply the generated power of the fuel cell 2 to the auxiliary equipment 4 in the power plant, and the surplus power is consumed by the dummy load 5. In this state, power is supplied to the auxiliary machine 4 and the dummy load 5 through the route of the fuel cell 2 → the inverter 6 → the power supply changeover switch S3.

The "standby operation" is a state in which the fuel cell power plant is operated independently and is in a standby state in which power can be supplied to the power system when necessary. The power generated by the fuel cell 2 is used to supply power to the battery 4. Further, in the “interconnection operation”, the interconnection switch S is connected to the power system 7 to supply power to the system load 9.
1 is turned on and the power generated by the fuel cell 2 is converted to the inverter 6 →
Power is supplied to the electric power system 7 through the route of the interconnection switch S1 → the interconnection switch S2, and the inverter 6 controls the output of the power transmission end so that the output value becomes the output value instructed from the outside. When an abnormality occurs on the electric power system side during the interconnection operation, the system switch S2 is turned off and the operation mode is switched to the "standby operation".

On the other hand, in the "power generation / cooling" step of the "stop operation", the interconnection switch S1 is turned off and the inverter 6
Is disconnected from the electric power system 7, and the fuel cell 2 is forcibly cooled by cooling water and lowered to a predetermined temperature while performing power generation (the inverter 6 is operated independently). When it arrives, it moves to the next "stop" step and the power supply changeover switch S3 is turned off and S4 is turned on.
After switching to, the inverter 6 is stopped, the supply of the reaction gas to the fuel cell 2 is also stopped to completely stop the power generation, and the reforming system and the inside of the cell are purged with nitrogen gas to stop the storage. To do. In addition, the above-mentioned operation mode instructions are given by the operator's input on the operation panel or by remote control.
The operation control based on this instruction is automatically programmed.

[0008]

By the way, as described above, in addition to the interconnection switches S1 and S2, the power supply changeover switches S3 and S4 are provided in the power supply circuit to the auxiliary equipment to switch the power supply in response to the switching of the operation mode. The conventional operation method of switching the switches S3 and S4 has the following drawbacks. That is, 1) The circuit of the operation control system including the power supply changeover switch becomes complicated.

2) If the switches S3 and S4 are turned on at the same time when the power supply changeover switches S3 and S4 are switched, there is a possibility that the output voltage of the inverter 6 and the system voltage may be mixed, so that one switch is turned off. After confirming, the other switch is turned on. For this reason, both switches are turned on while switching the switches.
A state occurs in which FF occurs and power supply to the auxiliary device 4 is interrupted.

In addition, depending on the auxiliary equipment, even if the power supply is interrupted, the operation may be hindered. In this case, the auxiliary power supply, the electrolytic capacitor, etc. are used for backup to prevent the instantaneous supply of power to the auxiliary equipment. The method is adopted. However, such a backup method complicates and enlarges the system and increases the equipment cost. The present invention has been made in view of the above points, and an object thereof is to solve the problems described above, and to simplify the circuit and to enable power supply to an auxiliary machine without interruption even when switching operation modes. An object of the present invention is to provide a method of operating a fuel cell power generator and an auxiliary equipment power supply circuit.

[0011]

In order to achieve the above object, the operating method of the present invention comprises a "start-up", a "standby operation",
For each operation mode of "interconnection operation" and "stop operation",
The inverter shall be operated in an interconnected state with the power grid in each operation mode of the "power generation temperature increase" step at start-up and the "power generation temperature decrease" step at stop operation, including the "interconnection operation".

Further, a power supply circuit of the present invention for carrying out the operating method is branched from a power transmission circuit connecting an inverter and a power system to connect an auxiliary power supply circuit of a fuel cell power plant, and the auxiliary machine. On the inverter side of the main circuit across the branch point of the power supply circuit, the "regeneration temperature rise" step at startup of the fuel cell power plant and the "power generation temperature rise at startup" excluding the "stop" step during stop operation Connect the interconnection switch that turns on the switch in each operation mode of the step, "standby operation", "interconnection operation", and "power temperature reduction" step during stop operation, and set "standby operation" on the power system side. Connect the interconnection switch that turns on the switch in each operating mode except "start", "interconnection operation", and "stop operation".

[0013]

According to the auxiliary equipment power supply circuit and the operating method having the above-described configurations, the power generation of the power transmission circuit is performed corresponding to each of the operation modes of "startup", "standby operation", "interconnection operation", and "stop operation". By simply switching the two interconnection switches connected to the plant side and the system side, power can be continuously supplied to auxiliary equipment without interruption. This eliminates the need for a backup system for preventing instantaneous interruption of power supply to the auxiliary equipment, and simplifies the auxiliary equipment power supply circuit including the operation control system.

[0014]

Embodiments of the present invention will be described below with reference to FIGS. 1 (a) and 1 (b). In the circuit diagram of the embodiment, devices corresponding to those in FIG. 2 are designated by the same reference numerals. That is, FIG.
In the circuit diagram of (a), the inverter 6 and the power system 7
While branching from an intermediate point P of a power transmission circuit 12 that connects to the auxiliary power supply circuit 13 for the auxiliary power supply 4 of the fuel cell power plant 1, the auxiliary circuit of the main circuit is connected with the branch point P of the auxiliary power supply circuit 13 interposed therebetween. The interconnection switch S1 is connected to the inverter 6.
However, an interconnection switch S2 is connected to the electric power system 7, respectively. Here, the interconnection switch S1 is "started", as shown in the time chart of FIG.
For each operation mode of "standby operation", "interconnection operation", and "stop operation", "reforming temperature increase" step at the time of starting the fuel cell power plant 1, and "stop" at the time of stop operation
It is turned ON in each operation mode of the "power generation temperature rise" step at startup except for steps, "standby operation", "interconnection operation", and "power generation temperature reduction" step at stop operation. On the other hand, the interconnection switch S2 is turned on in each operation mode of "start", "interconnection operation", and "stop operation" excluding "standby operation".
It is thrown into N. Then, the inverter 6 is stopped in the "reformation temperature rise" step at the time of startup and the "stop" step in the stop operation, the islanding operation in the "standby operation" mode, and the "power generation temperature rise" step at the time of startup. In the "power generation / cooling" step during stop operation, and in the "interconnection operation" mode, operation is performed in an interconnection state with the power grid. If any abnormality occurs in the electric power system 7 in the "interconnection operation" mode, the interconnection switch S2 is turned off to switch to the "standby operation" mode, and if the electric power system 7 returns to the normal state, the "interconnection operation" is resumed. operation"
Switch to mode.

Here, in the "reforming temperature raising" step at the time of starting the power generation plant 1 and the "stop" step at the time of the stopping operation, the route of the power system 7-> interconnection switch S2-> auxiliary equipment power supply circuit 13 is supplemented. Power is supplied to the machine 4. Also,
"Power generation temperature rise" step at startup, "Interconnection operation" mode,
In the "power generation and cooling" step at the time of the stop operation, under the condition of interconnection with the power system 7, the power is supplied to the auxiliary machine 4 from the fuel cell 2 → the inverter 6 → the interconnection switch S1 → the auxiliary machine power supply circuit 1
Take route 3 In the "standby operation" mode, the inverter 6 is operated independently, and the auxiliary equipment 4 is operated as described above.
Power supply to fuel cell 2 → inverter 6 → interconnection switch S
1 → The route of the auxiliary equipment power supply circuit 13 is performed.

That is, in the conventional operation method described in FIG. 2, the inverter 6 is operated independently in the "power generation temperature rising" step at the time of startup and the "power generation temperature decrease" step at the time of stop operation.
While the power supply changeover switches S3 and S4 were switched at the time of step switching between "start" and "stop", in the embodiment of the present invention shown in FIG. Therefore, in the operating state after the startup is established, the normal "interconnection operation" mode is set as long as there is no abnormality on the power system side, and the power supply to the auxiliary equipment is Can be continuously performed without interruption during the entire period of starting, generating, and stopping the power plant.

[0017]

As described above, according to the present invention, as compared with the conventional operation system, the power supply changeover switch connected to the auxiliary machine power supply circuit can be omitted, and the auxiliary machine movement generated when the power supply changeover switches are switched. A backup system that prevents momentary power interruptions is no longer required, which allows the auxiliary power supply circuit,
In addition, the control system related to switch switching can be greatly simplified.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a power supply circuit diagram between a fuel cell power generation plant and a power system, and (b) is a time chart diagram showing an operating method of a fuel cell power generation device.

FIG. 2 shows a conventional fuel cell power generator, (a) is a power supply circuit diagram between a fuel cell power plant and a power system, and (b) is a time chart diagram showing an operating method of the fuel cell power generator.

[Explanation of symbols]

 1 Fuel Cell Power Plant 2 Fuel Cell 3 Reformer 4 Auxiliary Machine 5 Dummy Load 6 Inverter 7 Power System 12 Power Supply Main Circuit 13 Auxiliary Power Supply Circuit S1 Power Generation Plant Side Connection Switch S2 System Side Connection Switch

Claims (2)

[Claims] 1. A fuel cell power generator for converting direct-current power generated by a fuel cell into commercial alternating-current power by an inverter and supplying the power to a power system, including "start-up", "standby operation",
For each operation mode of "interconnection operation" and "stop operation",
It is characterized by operating the inverter in an interconnection state with the power grid in each operation mode of the "power generation temperature rise" step at startup including "interconnection operation" and the "power generation temperature reduction" step at stop operation. Method of operating a fuel cell power generator. 2. A fuel cell power generation apparatus for converting direct-current power generated by a fuel cell into alternating-current power by an inverter and feeding the power system to a power system. The fuel cell power generation plant is branched from a power transmission circuit connecting the inverter and the power system. Auxiliary equipment power supply circuit is connected, and at the inverter side of the main circuit across the branch point of the auxiliary equipment power supply circuit, a "reforming temperature rising" step at the time of starting the fuel cell power plant and a "stop" at the time of stopping operation. Connect the interconnection switch that turns the switch ON in each operation mode of the "power generation temperature rise" step, "standby operation", "interconnection operation" at start-up excluding the "step", and the "power generation temperature reduction" step during stop operation However, it is characterized by connecting to the power system side an interconnection switch that turns on the switch in each operation mode of "start", "interconnection operation" and "stop operation" excluding "standby operation". Auxiliary power supply circuit of a fuel cell power plant.