JP2001351661A - Driving method of fuel cell power generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method of a fuel cell power generating device which prevents original fuel system, air system, and electric system of a fuel cell from temporary disturbance in the case of INV re-try at system irregularity, and aims to prevent the deterioration of the fuel cell. SOLUTION: At the system interconnection operation of the fuel cell, in the case of system irregularity, when standby operation of the fuel cell is carried out until system irregularity recovers, by instantaneously stopping an inverter, and restarting after prescribed period (T1), the system irregularity is detected at a system irregularity detecting part 31, and control indication value at an indicated/ measured value switching indication part 33 of INV re-try treatment part 32, such as current, voltage, flowing volume of original fuel, flowing volume of air, and a control indication value of fuel gas and oxidant gas at the supply system such as an original fuel valve and an air system blower, are switched from the existing value to the estimated value for the time of standby (time of re-try) at a switching part 36, and standby operation is continued after operating the fuel cell for a prescribed period (T2).

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 generation system for interconnecting a power company system and an inverter via an inverter.

[0002]

2. Description of the Related Art As is well known, a fuel cell continuously supplies a hydrogen-rich fuel reforming gas and an oxidizing gas (air) to electrochemically convert the energy of the fuel into electric energy. is there. It is also well known that such a fuel cell performs a system interconnection operation with an electric power company system via an inverter.

FIG. 2 shows an example of a schematic system diagram of a conventional fuel cell power generator.
Is a cell having a fuel electrode 21 and an oxidant electrode 22
A cooling plate through which cooling water flows is laminated for every eight layers, and a fuel gas and an oxidizing gas are supplied to the fuel electrode 21 and the oxidizing electrode 22, respectively, to generate power. FIG.
, The fuel gas is supplied from the reformer 4 through the CO shift converter 5 to reduce the CO concentration.

[0004] Since the fuel cell generates heat with power generation, cooling is required during power generation, and its cooling water 40 is supplied to the steam separator 7.
Is supplied to the fuel cell body 20 via the pump 50 and the heat exchanger 30. The temperature of the cooling water is usually about 160 ° C. during the operation of the fuel cell, flows in the state of pressurized water, and is separated into gas and liquid by the steam separator 7. The water that has flowed out of the steam separator 7 cools the fuel cell body 20 after the temperature of the cooling water is controlled by the heat exchanger 30, and is returned to the steam separator 7.

[0005] The vapor separated by the steam separator 7 is
The raw fuel (gas) is introduced into the ejector 3 by the steam pipe 9, and is sucked from the raw fuel supply line 8 by the ejector suction force of the steam flow, and the mixture of the raw fuel and the steam is introduced into the reformer 4. The raw fuel is reformed into a hydrogen-rich gas by a reforming reaction in a reformer.

[0006] The raw fuel supply line 8 is provided with a raw fuel supply source 15.
A fuel and gas shutoff valve 10, a raw fuel control valve 1, and a desulfurizer 2 are provided between the fuel and the ejector 3, and the fuel (gas) supply amount is adjusted by the raw fuel control valve 1 according to the load of the fuel cell. .
Raw fuel such as city gas contains a sulfur component as a deodorant, and therefore a desulfurizer 2 is provided to remove the sulfur component. The supply amount of the oxidizing gas is also adjusted according to the load. Normally, the air flow rate is controlled by an air system blower (not shown). As described above, the supply system of the fuel gas and the oxidizing gas is controlled based on the output voltage and the output current of the fuel cell.

[0007] A part of the raw fuel is supplied to the auxiliary combustion gas supply line 14.
Is also supplied to the reformer 4. Auxiliary gas supply line 14
The fuel supply line 8 branches from the raw fuel cutoff valve 10 and the raw fuel control valve 1 in the raw fuel supply line 8 and includes an auxiliary gas shutoff valve 13. Since the reaction of the reformer 4 is an endothermic reaction, heat needs to be supplied. This heat is mainly provided by off-gas combustion of fuel gas not consumed in the power generation reaction in the fuel cell. At the time of startup, auxiliary fuel is required, and the auxiliary combustion gas is used as the auxiliary fuel.

FIG. 3 shows a schematic configuration in a case where a conventional fuel cell power generation system is used in a customer premises by being connected to a power company system. FIGS. 3A and 3B show the relationship between the drawing and FIG.
Although separately shown in the figure, the right end of the figure (a) and the u point shown at the left end of the figure (b) are connected to constitute one system (for details, refer to Japanese Patent Application No. 11-166311). ).

In FIG. 3, reference numeral 100 denotes a fuel cell;
Is an inverter that converts the DC power of the fuel cell into AC power synchronized with the frequency of the power company system. here,
The configuration of the inverter itself and the control circuit are omitted. 41
Is a voltage detector for detecting the inverter output voltage, and 51 is a current detector for detecting the inverter output current.

Reference numeral 300 denotes a P set value as an output active power set value of the inverter 2, a Q set value as an output reactive power set value, an output signal v1 of the voltage detector 41, and an output of the current detector. Signal i1 is input to the inverter 20
In order to perform feedback control of the output active power value and the output reactive power value of 0, a deviation command signal p between the P set value and the active power output of the inverter and a deviation command signal q between the Q set value and the reactive power output of the inverter Is a PQ command control device that outputs

Reference numeral 80 denotes a disconnecting switch for disconnecting the fuel cell power generator when an abnormality occurs in the power company system. Reference numeral 90 denotes a short-circuit current when a short circuit accident or the like occurs in the fuel cell power generator. Reference numeral 110 denotes auxiliary devices that consume electric power, such as a pump and a blower (not shown) for maintaining the fuel cell power plant.

Reference numeral 130 denotes a power company system, in which a breaker 121 and a power receiving transformer 120 in a customer power receiving facility are provided.
, Power is supplied to various in-house loads (not shown) by the load feeder line 123. The fuel cell power generation device also performs an interconnection operation with the power company system 130 in synchronization with the system frequency via the circuit breaker 121, the power receiving transformer 120, and the circuit breaker 122.

[0013] A fuel cell feeder line 111, which is an indoor or outdoor wiring, is laid from the customer's power receiving equipment to the fuel cell power generator. Power generated by the fuel cell power generator is supplied to the customer premises via the feeder line 111. Have been.

As described above, a fuel cell that generates DC power by the reaction between a fuel gas and an oxidant gas, and a DC output of this fuel cell that is converted into an AC output and connected to an electric power company system for operation. In a fuel cell power generator including an inverter that operates in synchronization with the system frequency, when an abnormality occurs in the system, the inverter is instantaneously stopped by a disconnection switch, and after a predetermined time (T1), for example, About 200m
Normally, the fuel cell is restarted after s, and the fuel cell is in standby operation until the system abnormality is recovered.

In this case, power is supplied from the inverter to the auxiliary equipment of the fuel cell, and if necessary, a dummy load is used.
Standby by continuing low load operation.

[0016]

By the way, in the above-described system cooperative operation, when the inverter is momentarily stopped and restarted (hereinafter also referred to as INV retry) when the system is abnormal, in the case of the conventional operation method, Since there is no normal main load except for auxiliary equipment, the detected current value of the fuel cell temporarily decreases significantly and the voltage increases. Raw fuel flow,
The control of the supply system of the fuel gas and the oxidizing gas, such as the flow rate of the oxidizing gas, outputs a control command value based on the detected value.

Therefore, the raw fuel system, the air system,
The electrical system has been temporarily disturbed, stressing the fuel cell, degrading the fuel cell and shortening its life.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a temporary fuel system, air system, and electric system for a fuel cell in an INV retry at the time of system abnormality. It is an object of the present invention to provide a method of operating a fuel cell power generation device which prevents mechanical disturbance and eventually prevents deterioration of a fuel cell.

[0019]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a fuel cell which generates DC power by a reaction between a fuel gas and an oxidizing gas, and converts a DC output of the fuel cell into an AC output. Then, in order to operate the fuel cell power generator including an inverter that operates in synchronization with the system frequency in order to perform an interconnection operation with the power company system, the inverter is instantaneously stopped when a system abnormality occurs, and the operation is stopped for a predetermined time (T
1) When the fuel cell is restarted later and the fuel cell is in standby operation until the system abnormality is recovered, the output voltage value and the current value of the fuel cell at the time of the restart are temporarily changed to the auxiliary equipment of the fuel cell. A predetermined value required for the operation is set, the supply system of the fuel gas and the oxidizing gas is controlled based on the set value, and after the fuel cell is operated for a predetermined time (T2), the standby operation is continued. (Invention of claim 1).

As described above, in the INV retry, the output voltage value and the current value of the fuel cell predicted according to the low load of the necessary auxiliary equipment and the like are set for a predetermined time (T2), and based on this set value. Thus, the supply system of the fuel gas and the oxidizing gas is controlled, so that the raw fuel system, the air system, and the electric system of the fuel cell as described above do not cause temporary disturbance. The predetermined time (T2) is desirably about 1 second, which exceeds the time required for soft start of the inverter, for example, 500 to 600 ms.

In the operating method according to the first aspect of the present invention, at the time of the restart, in addition to the voltage value and the current value, control of a fuel gas and an oxidizing gas supply system such as a raw fuel flow rate and an oxidizing gas flow rate. The command value is also set to a predicted predetermined value necessary for operation of the auxiliary equipment of the fuel cell, and after the fuel cell has been operated for a predetermined time (T2), the standby operation is continued. invention). This eliminates the set voltage value and the current value, and the time delay of the control of the gas supply system,
A more favorable INV retry operation becomes possible.

[0022]

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

FIG. 1 is a functional block diagram of a control device in a fuel cell power generator according to an embodiment of the present invention.
The control device illustrated in FIG. 1 includes a system abnormality detection unit 31 and an INV
And a retry processing unit 32. In the system interconnection operation, the INV retry processing unit 32 outputs, for example, an abnormality 1 to 5
Is detected, the disconnecting switch 80 shown in FIG.
To restart the inverter after a predetermined time (T1), for example, 200 ms. As a result, electric power is supplied to the auxiliary device 110 shown in FIG. 3, and the fuel cell 100 is operated in a standby mode.

The INV retry processing section 32 has a command / measurement value switching command section 33. For example, the current, voltage, raw fuel flow rate, air flow rate, fuel gas such as raw fuel valve, air system blower, etc. The control command value of the agent gas supply system is switched from the current value to the predicted set value at the time of standby (at the time of retry) in the switching unit 36, and the fuel cell is operated for a predetermined time (T
2) For example, a function is provided for performing control to continue standby operation after driving for 1 second.

According to the above, a reasonable INV retry operation can be performed without causing any temporary disturbance in the raw fuel system, air system, and electric system of the fuel cell.

[0026]

As described above, the present invention relates to a fuel cell that generates DC power by the reaction between a fuel gas and an oxidizing gas, and converts the DC output of the fuel cell into an AC output, which is linked to a power company system. In the operation method of the fuel cell power generator including an inverter that operates in synchronization with the system frequency in order to perform system operation, the inverter is instantaneously stopped when a system abnormality occurs, and restarted after a predetermined time (T1). When performing standby operation of the fuel cell until the system abnormality is recovered,
The output voltage value and the current value of the fuel cell at the time of restart are temporarily set to predetermined values necessary for the operation of auxiliary equipment of the fuel cell, and the fuel gas and the oxidizing gas are set based on the set values. By controlling the supply system and operating the fuel cell for a predetermined period of time (T2), the standby operation is continued to temporarily disturb the raw fuel system, air system, and electric system of the fuel cell during INV retry when the system is abnormal. Can be prevented, and the deterioration of the fuel cell can be prevented.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a control device according to an embodiment of the present invention.

FIG. 2 is a schematic system diagram showing an example of a conventional fuel cell power generator.

FIG. 3 is a schematic system diagram of a conventional fuel cell power generator that performs system interconnection.

[Explanation of symbols]

31: system abnormality detecting unit, 32: INV retry processing unit,
33: command / measured value switching command section, 36: switching section, 80:
Switch for disconnection, 100: fuel cell, 110: auxiliary machine, 13
0: Power company system, 200: Inverter.

Claims (2)

[Claims] 1. A fuel cell for generating DC power by a reaction between a fuel gas and an oxidizing gas, and a system frequency for converting a DC output of the fuel cell into an AC output and for interconnecting operation with a power company system. In a method of operating a fuel cell power generator including an inverter that operates in synchronization with a fuel cell, the inverter is instantaneously stopped when a system abnormality occurs, restarted after a predetermined time (T1), and the fuel cell is restarted until the system abnormality recovers. When the standby operation is performed, the output voltage value and the current value of the fuel cell at the time of restart are temporarily set to predetermined values required for the operation of the auxiliary equipment of the fuel cell, and based on this set value. A method for operating a fuel cell power generator, comprising: controlling a fuel gas and oxidizing gas supply system, operating a fuel cell for a predetermined time (T2), and continuing standby operation. 2. The operating method according to claim 1, wherein at the time of the restart, a control command for a fuel gas and oxidizing gas supply system such as a raw fuel flow rate and an oxidizing gas flow rate in addition to a voltage value and a current value. A method for operating a fuel cell power generator, comprising setting a value to a predetermined value required for operation of an auxiliary device of a fuel cell, and operating the fuel cell for a predetermined time (T2), and then continuing standby operation. .