JP2014182884A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply output power of a fuel cell neither too much nor too little as further as possible with respect to power consumption required during independent power generation operation in a fuel cell system.SOLUTION: During an independent preparation operation that is an operation until output power of a fuel cell becomes first power corresponding to maximum power consumption of a variable load device during an independent power generation operation, a control device controls the variable load device so as to increase power consumption of the variable load device at a first predetermined speed (step S202), derives a raw fuel throw-in amount to be supplied by a raw fuel supply device from a value which is obtained by adding an offset value corresponding to the increase of the power consumption of the variable load device to be controlled to an output current value detected by a current sensor, and a map or a relational expression indicating a relation between the raw fuel throw-in amount and an output current of the fuel cell (step S204), and controls the raw fuel supply device in such a manner that a raw fuel supply amount becomes the derived raw fuel throw-in amount (step S206).

Description

  The present invention relates to a fuel cell system.

  As one type of fuel cell system, one shown in Patent Document 1 is known. In the fuel cell system, when a power failure occurs in the system, the power receiving system is disconnected from the system, and power is supplied from the fuel cell power generator as an emergency power source to the self-sustained load of the power receiving system. In this case, the interconnection circuit breaker is shut off and the inverter is temporarily stopped, and the raw fuel, reaction air, and reforming steam corresponding to the maximum electric output that the fuel cell power generation apparatus can supply to the self-supporting load are supplied in advance. In addition, after confirming the connection of the self-supporting load, the inverter is restarted.

JP 2005-203145 A

  However, in the fuel cell system described above, the necessary raw fuel is set according to the output current even during the independent power generation operation. On the other hand, since the internal resistance of the fuel cell varies depending on the temperature of the fuel cell itself, the environmental temperature, and the accumulated operation time, the output voltage changes and the output current also changes. Therefore, when the output power is smaller than the required power consumption, the electrodes of the fuel cell are oxidized and deteriorated. On the other hand, when the output power is greater than the required power consumption, the heat balance of the fuel cell is lost and the temperature of the fuel cell rises significantly. As described above, various problems occur when the output power is excessive or insufficient with respect to the necessary power consumption.

  The present invention has been made to solve the above-described problems, and aims to supply the output power of the fuel cell as much as possible to the required power consumption during the self-sustaining power generation operation in the fuel cell system. To do.

  In order to solve the above-described problem, a fuel cell system according to claim 1 is configured such that a fuel cell that generates power using fuel and an oxidant gas, a current sensor that detects an output current of the fuel cell, and power transmission of the system power supply are stopped. And a variable load device capable of variably controlling the power consumption by supplying only the output power from the fuel cell during the self-sustaining power generation operation of generating power from the system power source and the fuel cell disconnected from the system power source. A fuel cell system, further comprising: a raw fuel supply device that supplies raw fuel that is a raw material of fuel to the fuel cell system; and a control device that controls the fuel cell system, the control device being in a self-sustaining power generation operation During the self-supporting operation, which is the operation until the output power of the fuel cell reaches the first power amount corresponding to the maximum power consumption of the variable load device, the power consumption of the variable load device is A first variable load device control unit that controls the variable load device so as to increase at a predetermined speed, and a variable load device that is controlled by the first variable load device control unit to an output current value detected by a current sensor Supplied by the raw fuel supply device from a value obtained by adding an offset value corresponding to the amount of increase in power consumption and a map or relational expression showing the relationship between the input amount of raw fuel and the output current of the fuel cell A first raw fuel input amount deriving unit for deriving the raw fuel input amount, and a raw fuel supply device so that the raw fuel supply amount becomes the raw fuel input amount derived by the first raw fuel input amount deriving unit And a first raw fuel supply control unit that controls the engine.

  According to a second aspect of the present invention, in the fuel cell system according to the first aspect, the control device causes the output power of the fuel cell to exceed the first power amount during the self-sustaining power generation operation after the self-sustaining preparation operation is completed. When increasing to the second power amount, the variable load is set so that the total power consumption of the load device and the variable load device during the independent operation to which the output power is supplied only during the autonomous power generation operation is increased at the second predetermined speed. An offset value corresponding to an increase in total power consumption controlled by the second variable load device control unit is added to the output current value detected by the second variable load device control unit that controls the device and the current sensor. The second raw fuel input for deriving the raw fuel input amount supplied by the raw fuel supply device from the obtained value and the map or relational expression showing the relationship between the input amount of the raw fuel and the output current of the fuel cell Quantity derivation And a second raw fuel supply control unit that controls the raw fuel supply device so that the supply amount of the raw fuel becomes the raw fuel input amount derived by the second raw fuel input amount deriving unit. Yes.

  According to a third aspect of the present invention, in the fuel cell system according to the first or second aspect, the control device adjusts the power consumption of the variable load device when surplus power is generated in the output power of the fuel cell. The surplus power is consumed, and the surplus power adjusting unit that controls the output power to be constant at the first power amount or the second power amount is further provided.

  According to a fourth aspect of the present invention, in the fuel cell system according to any one of the first to third aspects, the control device corrects the offset value to increase as the accumulated operation time of the fuel cell increases. And a first offset setting unit.

  According to a fifth aspect of the present invention, there is provided a fuel cell system according to any one of the first to fourth aspects, wherein a reforming unit that generates fuel from raw fuel and reforming steam, and a fuel cell are modified. And a temperature sensor that detects a temperature inside the housing, and the control device detects an offset value by using the temperature sensor, and the temperature inside the housing is low. A second offset setting unit that corrects the value to become larger is further provided.

  In the invention according to claim 1 configured as described above, the first variable load device control unit is in a self-sustaining power generation operation, and the output power of the fuel cell corresponds to the maximum power consumption of the variable load device. During the self-sustaining preparation operation, which is an operation until the amount of electric power becomes 1, the variable load device is controlled so as to increase the power consumption of the variable load device at the first predetermined speed. The first raw fuel input amount deriving unit adds an offset value corresponding to an increase in power consumption of the variable load device controlled by the first variable load device control unit to the output current value detected by the current sensor. The raw fuel input amount supplied by the raw fuel supply device is derived from the obtained value, a map or a relational expression showing the relationship between the input amount of the raw fuel and the output current of the fuel cell. Then, the first raw fuel supply control unit controls the raw fuel supply device so that the raw fuel supply amount becomes the raw fuel input amount derived by the first raw fuel input amount deriving unit. As a result, during the self-supporting operation, the variable load device that consumes the output power of the fuel cell is raised at a predetermined speed, and the fuel cell outputs at an increase rate corresponding to the increase in the power consumption of the variable load device Raw fuel can be input so that current and thus output power can be generated. Therefore, during the self-sustaining power generation operation, the output power of the fuel cell can be supplied as much as possible with respect to the necessary power consumption.

  In the invention according to claim 2 configured as described above, in the fuel cell system according to claim 1, the control device controls the output power of the fuel cell during the self-sustaining power generation operation after the self-sustained preparation operation is completed. When the power amount is increased beyond the first power amount to the second power amount, the total power consumption of the load device and the variable load device during the self-sustaining operation in which output power is supplied only during the self-sustaining power generation operation is set at the second predetermined speed. A second variable load device control unit that controls the variable load device to increase the output current value detected by the current sensor, and an increase in the total power consumption controlled by the second variable load device control unit. The raw fuel input amount supplied by the raw fuel supply device is derived from the value obtained by adding the corresponding offset value and the map or relational expression showing the relationship between the input amount of the raw fuel and the output current of the fuel cell. A second raw fuel input amount deriving unit and a second raw fuel supply device that controls the raw fuel supply device so that the raw fuel supply amount becomes the raw fuel input amount derived by the second raw fuel input amount deriving unit. And a fuel supply control unit. As a result, even during the self-sustained power generation operation after the completion of the self-sustained preparatory operation, the variable load device that consumes the output power of the fuel cell is increased at a predetermined speed, and the increase corresponding to the increase in the power consumption of the variable load device At a rate, the fuel cell can be charged so that it can generate output current and thus output power. Therefore, during the self-sustaining power generation operation, the output power of the fuel cell can be supplied as much as possible with respect to the necessary power consumption.

  In the invention according to claim 3 configured as described above, in the fuel cell system according to claim 1 or 2, when the surplus power is generated in the output power of the fuel cell, the control device has a variable load. It further includes a surplus power adjustment unit that adjusts the power consumption of the device to consume surplus power and controls the output power to be constant at the first power amount or the second power amount. As a result, during the self-sustaining power generation operation, the output power of the fuel cell can be more reliably supplied to the necessary power consumption without excess or deficiency.

  In the invention according to Claim 4 configured as described above, in the fuel cell system according to any one of Claims 1 to 3, the control device sets the offset value to a long cumulative operation time of the fuel cell. A first offset setting unit that corrects the value to become larger is further provided. As a result, the variable load device that consumes the output power of the fuel cell can be increased at a predetermined speed according to the length of the cumulative operation time of the fuel cell, and as a result, the amount of increase in power consumption of the variable load device can be increased. The raw fuel can be introduced so that the fuel cell can generate the output current and hence the output power at the rate of increase corresponding to.

  In the invention according to claim 5 configured as described above, in the fuel cell system according to any one of claims 1 to 4, the reforming unit that generates fuel from the raw fuel and the reforming steam. And a heat-insulating housing that houses at least the fuel cell and the reforming unit, and a temperature sensor that detects a temperature in the housing, and the control device detects the offset value by the temperature sensor. A second offset setting unit that corrects the temperature so that the temperature increases as the temperature in the housing decreases is further provided. As a result, the variable load device that is the consumption destination of the output power of the fuel cell can be raised at a predetermined speed in accordance with the temperature of the casing having heat insulation that houses at least the fuel cell and the reforming unit, and thus The raw fuel can be introduced so that the fuel cell can generate the output current and hence the output power at an increase rate corresponding to the increase in power consumption of the variable load device.

1 is a schematic diagram showing an embodiment of a fuel cell system according to the present invention. It is a schematic diagram of the generator shown in FIG. 3 is a flowchart of an operation when a power failure occurs in the fuel cell system according to the present invention. It is a flowchart of the subroutine which concerns on the self-supporting preparatory operation of the fuel cell system by this invention. It is a flowchart of the subroutine which concerns on derivation | leading-out of the input amount of the raw fuel of the fuel cell system by this invention. It is a flowchart of the subroutine which concerns after completion of the self-supporting preparatory operation of the fuel cell system by this invention. It is a figure which shows the relationship between raw fuel input amount and output current (output electric power). The upper part shows the change over time of the variable load device, and the lower part shows the change over time in the output current (output power) and the raw fuel input amount. It is a flowchart of the other subroutine which concerns on derivation | leading-out of the input amount of the raw fuel of the fuel cell system by this invention. It is a figure which shows the relationship between the temperature in a fuel cell module, and a temperature correction amount. It is a figure which shows the relationship between the temperature in a fuel cell module, and the internal resistance of a fuel cell. It is a figure which shows the relationship between the integral operation time of a fuel cell, and a temperature correction amount. It is a figure which shows the relationship between the integrated operation time of a fuel cell, and the internal resistance of a fuel cell. It is a time chart of the example of 1 control of the fuel cell system by the present invention. It is a schematic diagram of the fuel cell in other embodiment of the fuel cell system by this invention.

  Hereinafter, an example which is one of the embodiments of the fuel cell system according to the present invention will be described. FIG. 1 is a schematic diagram showing an outline of this fuel cell system. The fuel cell system includes a power generation unit 10 and a hot water storage unit 20.

  The power generation unit 10 includes a power generation device 11, a power supply board 13, and a fuel cell control device 19 (hereinafter referred to as a control device 19). The power generator 11 generates electric power (AC power in the present embodiment), and includes a generator 11a that generates DC power and a power converter 11b. As shown in FIG. 2, the generator 11 a includes a fuel cell module 40.

  The fuel cell module 40 includes a casing 41, an evaporation unit 42, a reforming unit 43, and a fuel cell 44. The casing 41 is formed in a box shape from a heat insulating material. In the casing 41, an evaporation section 42, a reforming section 43, a fuel cell 44, and a combustion space R3 that is a first combustion section 46 are disposed. The casing 41 is provided with a temperature sensor 41 b that detects the temperature inside the casing 41, and the detection result is output to the control device 19.

  The evaporating section 42 is heated by a combustion gas, which will be described later, and evaporates the supplied reforming water to generate steam, and preheats the supplied reforming raw material. The evaporation unit 42 mixes the steam generated in this way with the preheated reforming raw material and supplies a mixed gas to the reforming unit 43. As reforming raw materials, there are gas fuels for reforming such as natural gas and LPG, and liquid fuels for reforming such as kerosene, gasoline and methanol.

  One end (lower end) of the water supply pipe 51 provided in the water tank 61 is connected to the evaporation unit 42. The water supply pipe 51 is provided with a reforming water pump 51a. The reforming water pump 51a supplies reforming water to the evaporation section 42 and adjusts the reforming water supply amount (supply flow rate (flow rate per unit time)).

  Further, a reforming material from a reforming material supply source (hereinafter referred to as a supply source) Gs is supplied to the evaporation section 42 via a reforming material supply pipe 52. The supply source Gs is, for example, a gas supply pipe for city gas or a gas cylinder for LP gas. The reforming material supply pipe 52 is provided with a material pump 52a.

  The raw material pump 52 a is a supply device that supplies fuel to the fuel cell 44 (that is, a raw fuel supply device that supplies raw fuel (reforming raw material) as a fuel raw material to the fuel cell system). The fuel supply amount (supply flow rate (flow rate per unit time)) from the supply source Gs is adjusted according to the control command value. The raw material pump 52 a is a pumping device that sucks the raw material for reforming and pumps it to the reforming unit 43.

  The reforming unit 43 is heated by a combustion gas described later and supplied with heat necessary for the steam reforming reaction, so that the reformed gas is generated from the mixed gas (the reforming raw material and steam) supplied from the evaporation unit 42. Is generated and derived. The mixed gas reacts with a catalyst and is reformed to generate hydrogen gas and carbon monoxide gas (so-called steam reforming reaction). At the same time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide and hydrogen produced by the steam reforming reaction react to transform into hydrogen gas and carbon dioxide. These generated gases (so-called reformed gas) are led out to the fuel electrode of the fuel cell 44. The reformed gas contains hydrogen, carbon monoxide, carbon dioxide, steam, unreformed natural gas (methane gas), and reformed water (steam) that has not been used for reforming. As described above, the reforming unit 43 generates reformed gas that is fuel from the reforming raw material and the reformed water, and supplies the reformed gas to the fuel cell 44.

  The fuel cell 44 generates power using fuel and oxidant gas. The fuel cell 44 is configured by laminating a fuel electrode, an air electrode (oxidant electrode), and a plurality of cells 44a made of electrolyte interposed between the two electrodes in the left-right direction in FIG. The fuel cell 44 of this embodiment is a solid oxide fuel cell, and uses zirconium oxide, which is a kind of solid oxide, as an electrolyte. Hydrogen, carbon monoxide, methane gas or the like as fuel is supplied to the fuel electrode of the fuel cell 44. On the fuel electrode side of the cell 44a, a fuel flow path 44b through which the reformed gas as the fuel flows is formed. An air flow path 44c through which air (cathode air) that is an oxidant gas flows is formed on the air electrode side of the cell 44a. Cathode air is supplied to the air flow path 44c by a cathode air blower 54a (or a cathode air pump). The fuel cell 44 is provided with a temperature sensor 44 d that detects the temperature inside the fuel cell 44, and the detection result is output to the control device 19.

  The fuel cell 44 is provided on a manifold 45 as shown in FIG. The reformed gas from the reforming unit 43 is supplied to the manifold 45 via the reformed gas supply pipe 53. The lower end (one end) of the fuel flow path 44b is connected to the fuel outlet of the manifold 45, and the reformed gas led out from the fuel outlet is introduced from the lower end and led out from the upper end. . A cathode air supply channel 54 having one end connected to the cathode air blower 54a is communicated with the lower end of the air channel 44c so that the cathode air is introduced from the lower end of the air channel 44c and led out from the upper end. It has become.

In the fuel cell 44, power generation is performed by the fuel supplied to the fuel electrode and the oxidant gas supplied to the air electrode. That is, the reaction shown in Chemical Formula 1 and Chemical Formula 2 below occurs at the fuel electrode, and the reaction shown in Chemical Formula 3 below occurs at the air electrode. That is, oxide ions (O ²⁻ ) generated at the air electrode pass through the electrolyte and react with hydrogen at the fuel electrode to generate electrical energy. Therefore, the reformed gas and the oxidant gas (air) that have not been used for power generation are derived from the fuel flow path 44b and the air flow path 44c.
(Chemical formula 1)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻
(Chemical formula 2)
CO + O ²⁻ → CO ₂ + 2e ⁻
(Chemical formula 3)
1 / 2O ₂ + 2e ⁻ → O ²⁻

  Then, the reformed gas (anode off gas) derived from the fuel flow path 44b and the air flow path 44c and not used for power generation enters the combustion space R3 between the fuel cell 44 and the evaporation section 42 (reforming section 43). The oxidant gas (cathode off-gas) that has not been used for power generation is burned, and the evaporation part 42 and the reforming part 43 are heated by the combustion gas (flame 47). Furthermore, the inside of the fuel cell module 40 is heated to the operating temperature.

  As described above, the combustion space R3 is the first combustion unit 46 that heats the reforming unit 43 by burning the anode off-gas from the fuel cell 44 and the cathode off-gas from the fuel cell 44. That is, the first combustion unit 46 is a combustion unit that introduces a combustible gas containing unused fuel from the fuel cell 44 and burns it with an oxidant gas to derive the combustion gas.

In the first combustion section 46 (combustion space R3), the anode off gas is burned and a flame 47 is generated. Thereafter, the combustion gas generated in the combustion space R3 is exhausted out of the fuel cell module 40 through the outlet 41a.
The first combustion unit 46 is provided with a pair of ignition heaters 46a1 and 46a2 for igniting the anode off gas. The ignition heaters 46a1 and 46a2 are AC power supply load devices. The total power consumption of the ignition heaters 46a1 and 46a2 is 100W in total.

  The exhaust heat recovery system is an exhaust heat recovery system that recovers and stores exhaust heat in stored hot water by exchanging heat between the exhaust heat of the fuel cell module 40 and the stored hot water. The exhaust heat recovery system includes a hot water tank 21 for storing hot water, a hot water circulation line 24 for circulating the hot water, and a heat exchanger for exchanging heat between the combustion exhaust gas from the fuel cell module 40 and the hot water. 25.

  The hot water storage tank 21 is provided with one columnar container, in which hot water is stored in a layered manner, that is, the temperature of the upper part is the highest and lower as it goes to the lower part, and the temperature of the lower part is the lowest. It has become so. Water (low temperature water) such as tap water is replenished to the lower part of the columnar container of the hot water tank 21, and hot hot water stored in the hot water tank 21 is led out from the upper part of the columnar container of the hot water tank 21. ing.

  One end of the hot water circulation line 24 is connected to the lower part of the hot water tank 21, and the other end is connected to the upper part of the hot water tank 21. A hot water circulation pump 24a, a heat exchanger 25, and a hot water heater 24b are disposed on the hot water circulation line 24 in order from one end to the other.

  The hot water circulating pump 24a sucks in hot water stored in the lower part of the hot water tank 21, passes the hot water circulating line 24 in the direction of the arrow in the drawing, and discharges it to the upper part of the hot water tank 21, and its flow rate (delivery amount) is controlled. It has come to be. The hot water circulating pump 24a is controlled in its delivery amount so that the temperature detected by a temperature sensor (not shown) (the temperature at the inlet of the hot water storage hot water tank 21) falls within a predetermined temperature or temperature range.

  The hot water storage heater 24b is a heater for heating the hot water circulation line 24 to prevent freezing. This hot water heater 24b is a load device of an AC power supply. The total power consumption of the hot water heater 24b is 100W.

  The heat exchanger 25 is a heat exchanger that is supplied with the combustion exhaust gas exhausted from the fuel cell module 40 and is supplied with hot water from the hot water storage tank 21 to exchange heat between the combustion exhaust gas and the hot water. The heat exchanger 25 includes a casing 25a. The upper part of the casing 25a communicates with an outlet 41a provided at the lower part of the casing 41 of the fuel cell module 40 and from which the combustion exhaust gas is led out. An exhaust pipe 55 is connected to the lower part of the casing 25a. A condensed water supply pipe 56 connected to the pure water device 62 is connected to the bottom of the casing 25a. In the casing 25a, a heat exchanging portion 25b connected to the hot water circulation line 24 is disposed.

  In the heat exchanger 25 configured as described above, the combustion exhaust gas from the fuel cell module 40 is introduced into the casing 25a through the outlet 41a, and passes through the heat exchange section 25b through which the hot water is circulated. Heat is exchanged with water to be condensed and cooled. The condensed combustion exhaust gas is discharged to the outside through the exhaust pipe 55. Further, the condensed water condensed is supplied to the pure water device 62 through the condensed water supply pipe 56 (falls by its own weight). On the other hand, the hot water stored in the heat exchange unit 25b is heated and discharged.

  A second combustion section 48 is provided at the outlet 41 a of the casing 41. The second combustion section 48 is a first combustion section off-gas that is a gas exhausted from the first combustion section 46, that is, an unused combustible gas (for example, hydrogen, methane gas, one exhaust gas) exhausted from the first combustion section 46. Carbon oxide etc.) is introduced and burned out. The second combustion section 48 is composed of a combustion catalyst (for example, a ceramic honeycomb or a metal honeycomb and noble metal catalyst) that is a catalyst for burning a combustible gas.

  The second combustion section 48 is provided with a combustion catalyst heater 48a for heating the combustion catalyst to the catalyst activation temperature and burning the combustible gas. The combustion catalyst heater 48a is a load device of an AC power source. The combustion catalyst heater 48a can be variably controlled in power consumption, and its maximum power consumption is 200W. The combustion catalyst heater 48 a is controlled by an instruction from the control device 19.

  The ignition heaters 46a1 and 46a2 and the combustion catalyst heater 48a described above constitute a variable load device L (variable load device described in claims) that can control power consumption variably. This variable load device L supplies only the output power from the fuel cell 44 when the power transmission of the system power source 30 is stopped and during the self-sustaining power generation operation that generates power from the fuel cell 44 disconnected from the system power source 30. Thus, the variable load device can control the power consumption variably. The variable load device L may be configured by further adding a hot water heater 24b. In addition, the variable load device L may be configured not only by the load device inside the fuel cell system but also by a load device outside the fuel cell system, or by both internal and external load devices. May be.

  The fuel cell system also includes a water tank 61 and a pure water device 62. The water tank 61 stores the pure water derived from the pure water device 62. The deionizer 62 contains activated carbon and an ion exchange resin, and is filled with, for example, flaky activated carbon and a granular ion exchange resin. Depending on the state of the water to be treated, a hollow fiber filter may be installed. The deionizer 62 purifies the condensed water from the heat exchanger 25 with activated carbon and ion exchange resin. The deionizer 62 communicates with the water tank 61 through a pipe 57, and the deionized water in the deionizer 62 is led to the water tank 61 through the pipe 57.

  As shown in FIG. 1, a current sensor 11a1 is provided between the generator 11a and the power converter 11b. The current sensor 11 a 1 is a current sensor that detects the output current of the generator 11 a (that is, the fuel cell 44), and the detection result is transmitted to the control device 19. A power sensor may be provided instead of the current sensor 11a1.

  The power converter 11b converts the direct current supplied from the fuel cell 44 into an alternating current. The power converter 11b has a function of outputting the converted alternating current. One end of the power transmission line 14 is connected to the power conversion device 11b, and the AC power of the power conversion device 11b is output to the power transmission line 14. A first load device 15 is connected to the other end of the power transmission line 14. The power output from the power converter 11b is supplied to the first load device 15 via the power transmission line 14 as necessary. The first load device 15 is an electric appliance such as an electric lamp, iron, television, washing machine, electric kotatsu, electric carpet, air conditioner, and refrigerator.

  The sensor 11b1 is provided in the output part of the alternating current power of the power converter device 11b. The sensor 11b1 detects at least one of current and voltage output from the power conversion device 11b (fuel cell 44). If the sensor 11b1 detects both voltage and current, the load devices connected, for example, the ignition heaters 46a1 and 46a2, the combustion catalyst heater 48a, the hot water heater 24b, and the second load are multiplied by these values. The power consumption of the device 18 and the like is calculated. Further, when the sensor 11b1 detects any one of voltage and current, the control device 19 calculates the power consumption of the load device from any one of the detected values. Specifically, since the load device is an electric device used in the home, the load device used in the event of a power failure can be investigated in advance. The relationship between the voltage or current and power of a plurality of electrical devices selected from the survey results is grasped, and a table summarizing the power values corresponding to the voltage or current values is stored in the control program. In accordance with this table, the control device 19 calculates the power value corresponding to either the detected voltage or current as the power consumption of the load device.

  The power converter 11b also has a function of converting AC power from the system power supply 30 supplied via the power supply line 31 and the power transmission line 14 into DC power and outputting the DC power. The DC power output from the power conversion device 11 b is output to the power supply board 13. The power supply board 13 converts the supplied DC power into predetermined DC power and supplies it to the control device 19 and the auxiliary machine 10b. The auxiliary machine 10b is configured to operate with a direct current, which is necessary for operating the power generation unit 10 such as the reforming water pump 51a, the raw material pump 52a, and the temperature sensor of each part.

  On the power transmission line 14, between the power converter 11 b and the first load device 15, the other end of the power supply line 31 whose one end is connected to the system power supply 30 is connected by the connecting portion 14 a. A distribution board 32 is disposed on the power line 31. When the power consumption of the first load device 15 exceeds the power generated by the power generation unit 10, the insufficient power is supplied from the system power supply 30 from the power supply line 31 via the switchboard 32. . As described above, the first load device 15 is supplied with power from the system power supply 30 and power from the power conversion device 11b.

  A current sensor 31 a is disposed on the power supply line 31 between the system power supply 30 and the switchboard 32. The current sensor 31a detects a current of power supplied from the system power supply 30 to the power converter 11b. In the present embodiment, the current sensor 31a is provided to detect the current of the system power supply 30, but a power sensor that detects the power supplied from the system power supply 30 to the power converter 11b is provided. You may make it do.

  Moreover, the breaker 14b is arrange | positioned on the power transmission line 14 and between the power converter device 11b and the connection part 14a. The breaker 14b automatically opens the power transmission line 14 when power is transmitted from the system power supply 30 and an abnormal current (for example, overcurrent) flows through the power transmission line 14 for some reason. It has become.

  Moreover, the 1st switch 14c is provided on the power transmission line 14 between the power converter device 11b and the breaker 14b. The first switch 14c electrically disconnects or connects the power converter 11b and the system power supply 30 by opening or closing the circuit.

  A voltage sensor 100a is provided on the power transmission line 14 and between the breaker 14b and the first switch 14c. The voltage sensor 100 a detects the voltage at the arrangement location and outputs the detection result to the control device 19.

  In addition, the other end of the power transmission line 17a having one end connected to the self-sustained output terminal 16 is connected on the power transmission line 14 between the power conversion device 11b and the first switch 14c. The power transmission line 17a is provided with a second switch 17a1 and a power sensor 17a2. The second switch 17a1 is disposed between the power conversion device 11b and the self-supporting output terminal 16 (and thus the second load device 18), and is opened or closed, whereby the power conversion device 11b and the second load device 18 are opened. Is an opening / closing device that is electrically disconnected or connected. When power is supplied from the power conversion device 11 b to the second load device 18, the power sensor 17 a 2 detects the power consumption of the second load device 18 and outputs the detection result to the control device 19.

  When the power supply from the system power supply 30 is stopped (hereinafter referred to as a power failure), the output terminal 16 for self-sustained power generation is performed by the power generation device 11 (fuel cell 44) and only the power from the power conversion device 11b is second. It is used only during a power generation operation (hereinafter referred to as a self-sustained power generation operation) supplied to the load device 18. The second load device 18 is detachably connected to the self-supporting output terminal 16. The second load device 18 is an electric appliance similar to the first load device 15, but the electric appliance that the user wants to use is connected to the self-sustained output terminal 16 only during the self-sustaining power generation operation in the event of a power failure. It is what is used. The second load device 18 is supplied with output power from the fuel cell 44 only during the self-sustaining power generation operation.

  Further, the other end of the power transmission line 17b having one end connected to the ignition heaters 46a1 and 46a2 is connected on the power transmission line 14 between the power converter 11b and the first switch 14c (FIG. 2). reference). The power transmission line 17b is provided with a third switch 17b1. The third switch 17b1 is an open / close device that electrically disconnects or connects the power converter 11b and the ignition heaters 46a1 and 46a2 by opening or closing the circuit.

  Further, the other end of the power transmission line 17c having one end connected to the combustion catalyst heater 48b is connected on the power transmission line 14 between the power converter 11b and the first switch 14c. The power switch 17c is provided with a fourth switch 17c1. The fourth switch 17c1 is an open / close device that electrically disconnects or connects the power converter 11b and the combustion catalyst heater 48b by opening or closing the circuit.

  Further, the other end of the power transmission line 17d having one end connected to the hot water heater 24b is connected on the power transmission line 14 between the power converter 11b and the first switch 14c. The power transmission line 17d is provided with a fifth switch 17d1. The fifth switch 17d1 is a switch that electrically disconnects or connects the power conversion device 11b and the hot water heater 24b by opening or closing the circuit.

The control device 19 is for at least controlling the power generation device 11 (fuel cell 44) (for controlling the fuel cell system). Specifically, when power is supplied from the system power supply 30, the power generation amount of the fuel cell 44 is controlled so that the power consumption of the first load device 15 is achieved. At this time, when the power generated by the fuel cell 44 is lower than the power consumption of the first load device 15, the insufficient power is received from the system power supply 30 to compensate. In the case of a power failure, the amount of power generated by the fuel cell 44 is controlled to be a constant output power (for example, half of the rating (350 W)). The power generation amount of the fuel cell 44 may be controlled so that the power consumption of the second load device 18 is achieved.
The first to fifth switches 14c, 17a1, 17b1, 17c1, 17d1 are controlled to be opened and closed in accordance with instructions from the control device 19.

  The control device 19 receives a detection signal from the sensor 11b1. The control device 19 can detect a power failure of the system power supply 30 based on the detection signal of the sensor 11b1. Further, the control device 19 is configured to receive a detection signal of the current sensor 31a. The control device 19 may detect a power failure of the system power supply 30 based on the input signal of the current sensor 31a. Specifically, when the current of the system power supply 30 detected by the sensor 11b1 (or the current sensor 31a) is a predetermined current or less (for example, 1/10 or less of the rating), the system power supply 30 is detected as a power failure. The As described above, the current sensor 31a is disposed between the power generation device 11 and the system power supply 30, and detects at least one of the current and voltage at the disposed position (described above). May be used as

As shown in FIG. 1, the hot water storage unit 20 includes the hot water storage tank 21, the hot water storage tank control device 22, and the power supply substrate 23 described above.
Inside the hot water storage tank 21, a temperature sensor group 21a which is a remaining hot water amount detection sensor is provided. Based on the detection result of the hot water temperature at each position by the temperature sensor group 21a, the remaining hot water amount in the hot water storage tank 21 is derived by the hot water tank control device 22 to which the detection result of the temperature sensor group 21a is transmitted. It has become. The amount of remaining hot water represents the amount of heat stored in the hot water storage tank 21.

  A hot water supply pipe 26 is connected to the hot water storage tank 21. The hot water supply pipe 26 is provided with a gas water heater (not shown), a temperature sensor 26a, and a flow rate sensor 26b, which are auxiliary heating devices in order from the upstream. The gas water heater heats hot water from the hot water tank 21 passing through the hot water supply pipe 26 to supply hot water. The temperature sensor 26 a detects the temperature of the hot water after passing through the gas water heater, and the detection signal is transmitted to the hot water tank control device 22. The flow rate sensor 26 b detects the amount of hot water consumption (hot water supply amount) per unit time supplied from the hot water storage tank 21.

  The hot water supply pipe 26 is connected to a plurality of hot water use devices A2a installed in a hot water use place A2 that uses hot water stored in the hot water tank 21 as hot water supply. Examples of the hot water using equipment include a bathtub, shower, kitchen (kitchen faucet), and washroom (toilet faucet). Further, the hot water supply pipe 26 is connected to a heat utilization device A2b installed in a hot water use place A2 that uses hot water in the hot water tank 21 as a heat source. Examples of the heat utilization device include bathroom heating, floor heating, and a hot water bathing mechanism.

  The hot water tank control device 22 is connected to the control device 19 so as to communicate with each other. The hot water tank control device 22 controls the remaining hot water amount in the hot water tank 21 by operating the hot water circulating pump 24a to circulate and heat the hot water based on the detection result of the temperature sensor group 21a. The power supply board 23 converts AC power from the system power supply 30 into predetermined DC power and supplies it to the hot water tank control device 22.

  Further, the hot water storage unit 20 includes a hot water tank control remote controller 27. The hot water tank control remote controller 27 is connected to the hot water tank control device 22 so as to be communicable with each other. The hot water storage state of the hot water tank 21 such as the remaining hot water amount, hot water supply temperature and hot water consumption in the hot water tank 21, and the generator 11a. The operation status of the power generation unit 10 such as the power generated and the amount of power used is displayed.

  Next, an example of a basic operation when power is transmitted from the system power supply 30 of the fuel cell system described above will be described. When the start switch (not shown) is pressed and the operation is started, or when the operation is started according to the planned operation, the control device 19 starts the start-up operation. Here, when power is supplied from the system power supply 30, the control device 19 controls the first switch 14 c to be closed and the second switch 17 a 1 to be opened. Thus, when the power supply from the grid power supply 30 is normal, that is, when the generator 11a is grid-connected to the grid power supply 30, the generation of power by the generator 11a is referred to as grid-connected power generation.

  When the start-up operation is started, the control device 19 operates the auxiliary machine 10b such as a motor-driven pump and starts supplying fuel and reforming water to the evaporation unit 42 of the generator 11a. As described above, a mixed gas is generated in the evaporation unit 42, and the mixed gas is supplied to the reforming unit 43. In the reforming unit 43, the reformed gas is generated from the supplied mixed gas, and the reformed gas is supplied to the fuel cell 44. If the reforming unit 43 becomes equal to or higher than the predetermined temperature, the start-up operation is terminated and the steady operation (normal power generation operation) is started.

  During the normal power generation operation, the control device 19 controls the auxiliary device 10b so that the power generated by the generator 11a becomes the power of the first load device 15 calculated based on the detection signal from the sensor 11b1. Then, the reformed gas and the cathode air are supplied to the generator 11a. As described above, when the electric power of the first load device 15 exceeds the electric power generated by the generator 11a, the insufficient electric power is received from the system power supply 30 and compensated.

In such a power generation operation, when a stop switch (not shown) is pressed to stop the power generation operation, or when the operation is stopped according to the operation plan, the control device 19 stops the fuel cell system ( Stop processing).
The control device 19 stops drawing electric power from the fuel cell 44, and fuels the amount of raw fuel and water (reforming steam) supplied to the evaporation section 42 and air (reaction air) supplied to the air electrode. It changes according to the temperature of the battery module 40, and stops when the temperature of the fuel cell module 40 falls below a certain temperature.

  When such a stop operation ends, the fuel cell system enters a standby state (standby state). The standby state is the power generation stop state of the fuel cell system (that is, the start operation, the power generation operation, or the stop operation is not in progress), and waits for a power generation instruction (such as turning on the start switch). It is a state of being. That is, the state at the end of the stop operation state is maintained.

Next, an example of the operation of the fuel cell system when the system power supply 30 fails will be described with reference to the flowchart shown in FIG.
When the power supply from the system power supply 30 is normal, that is, the first switch 14c is closed, the second switch 17a1 is opened, and the generator 11a (fuel cell 44) is system-connected to the system power supply 30. If the system power supply 30 fails, the control device 19 determines “YES” in step S102 and advances the program to step S104. On the other hand, when the power supply from the system power supply 30 is normal, the process of step S102 is repeatedly executed. As described above, the power failure determination of the system power supply 30 is performed when the current of the system power supply 30 detected by the sensor 11b1 (or the current sensor 31a) is equal to or less than a predetermined current (for example, 1/10 or less of the rating) It is determined that the system power supply 30 is a power failure.

  In step S104, the control device 19 opens the first switch 14c so that the fuel cell 44 is disconnected from the system power source 30 and generates power only for the auxiliary power necessary for operation. Note that the output power may be consumed by the ignition heaters 46a1 and 46a2 and the combustion catalyst heater 48a which are internal load devices.

  When a predetermined time has elapsed from the start of power generation stop (determined as “YES” in step S106), control device 19 starts self-sustaining power generation (self-sustaining operation). The predetermined time is, for example, 5 minutes. Specifically, in step S108, the control device 19 repeatedly executes the program according to the flowchart of the subroutine shown in FIG. 4 every predetermined short time.

  In step S202, the control device 19 controls the variable load device L. Specifically, the control device 19 is in a self-sustaining power generation operation, and the output power of the fuel cell 44 becomes the first power amount (300 W in the present embodiment) corresponding to the maximum power consumption of the variable load device L. During the self-supporting preparatory operation, the variable load device L is controlled to increase the power consumption of the variable load device L at the first predetermined speed (first variable load device control unit).

  As described above, the variable load device L includes the ignition heaters 46a1 and 46a2 whose power consumption is fixed (100 W) and the combustion catalyst heater 48a whose power consumption is variable (0 to 200 W). Therefore, the power consumption of the variable load device L can be realized by maintaining the ignition heaters 46a1 and 46a2 in the OFF range and changing and controlling the power consumption of the combustion catalyst heater 48a in the range of 0 to 100W. In the range of 100 to 300 W, the ignition heaters 46a1 and 46a2 are kept on and the power consumption of the combustion catalyst heater 48a is changed and controlled.

  The first predetermined speed corresponds to an increase per hour in the input amount of raw fuel. However, the increase in the raw fuel is preferably set so as not to exceed the increase per unit time in the output power (output current) of the fuel cell 44.

  In step S204, the control device 19 derives the input amount of the raw fuel. Specifically, the control device 19 increases the power consumption of the variable load device L controlled in step S202 (first variable load device control unit) to the output current value detected by the current sensor 11a1 (described above). A value obtained by adding an offset value α (reference offset value α0) corresponding to the first predetermined speed) and a map or relational expression showing the relationship between the input amount of raw fuel and the output current of the fuel cell 44. The raw fuel input amount A supplied by the raw material pump 52a (raw fuel supply device) is derived (first raw fuel input amount deriving unit).

  This will be described with reference to FIGS. FIG. 7 is a map showing the relationship between the input amount of raw fuel and the output current of the fuel cell 44. The horizontal axis indicates the raw fuel input amount (supply amount), and the vertical axis indicates the output current (output power). Since the output power is constant, the vertical axis can be the output power. As shown in FIG. 7, when the raw fuel input amount is between 0 and A0, the output current is a constant value I0. When the raw fuel input amount exceeds A0, the output current increases as the raw fuel input amount increases (eg, has a direct proportional relationship). When the raw fuel input amount is A1, the output current is I1 + α0 (described later). The input amount is a flow rate per unit time.

  FIG. 8 shows the time variation of the power consumption of the variable load device L in the upper stage, and shows the output current I (thick solid line) and raw fuel input amount A (thin solid line) of the fuel cell 44 in the lower stage. The power consumption of the variable load device L is adjusted so as to increase at the first predetermined speed. At this time, the times from time t1 to time t2 and from time t2 to time t3 are the same at T, and the increase in power consumption during time T is ΔL. Time T is a control cycle time, and is set to 100 ms, for example. The reference offset value α0 is preferably set to a value corresponding to an increase in power consumption of the variable load device L (that is, a current corresponding to the load increase speed of the variable load device L). The amount of increase in power consumption of the variable load device L may be the first predetermined speed or an amount of increase for a predetermined time (ΔL in this embodiment).

  The process of step S204 is a process of executing a program according to the flowchart of the subroutine shown in FIG. In step S212, the output current value I detected by the current sensor 11a1 is acquired. In step S214, a reference offset value α0 corresponding to an increase in power consumption of the variable load device L is calculated. At this time, if the relationship between the rising speed and the reference offset value is measured and stored in advance, the reference offset value α0 can be calculated from the rising speed and the relationship. In step S216, the reference offset value α0 calculated in step S214 is added to the output current value I acquired in step S212 (addition value = I + α0). In step S218, the addition value calculated in step S216 and the map indicating the relationship between the input amount of raw fuel and the output current of the fuel cell 44 shown in FIG. 7 are used in accordance with the addition value calculated in step S216. The amount of raw fuel input is derived.

For example, as shown in FIG. 8, at time t2, the output current value I1 detected by the current sensor 11a1 is acquired (step S212). The reference offset value α0 is calculated from the increase (controlled) in the power consumption of the variable load device L (step S214). The added value (= I1 + α0) is calculated by adding the reference offset value α0 to the output current value I1 (step S216). Then, from the added value (I1 + α0) and the map shown in FIG. 7, the input amount A1 of the raw fuel corresponding to the added value (I1 + α0) is derived (step S218).
In addition, what is necessary is just to derive | lead-out each input amount of reforming steam and reaction air similarly to the input amount of raw fuel. At this time, the respective maps corresponding to FIG. 7 may be used for the input amounts of reformed steam and reaction air.

  The control device 19 returns the program to step S206 in FIG. 4, and in step S206, controls the raw material pump 52a so that the raw fuel input amount A1 derived in step S218 is obtained. The reforming water pump 51a is controlled to have a reforming steam input amount, and the cathode air blower 54a is controlled to have a reaction air input amount.

  The control device 19 repeats the determination of “NO” in step S110 until the output power of the fuel cell 44 reaches the first power amount (300 W), and continues the above-described independent preparation operation. On the other hand, when the output power of the fuel cell 44 exceeds the first power amount (300 W), the control device 19 determines “YES” in step S110, and ends the self-supporting preparation operation in step S112. In step S110, the output power may be calculated by multiplying the output current detected by the current sensor 11a1 by a constant output voltage, and the output power is a first current value corresponding to the first power amount. You may make it compare with. Further, the output power of the fuel cell 44 may be directly measured by a wattmeter. In addition, when using the detected value of the current sensor 11a1 for the calculation of the output power, the voltage of the fuel cell 44 is used to subtract the conversion efficiency of the auxiliary machine 10b and the power converter 11b.

  In step S112, the control device 19 completes the self-supporting preparation operation, and controls the fuel cell 44 to have a constant output power (for example, 300 W). Further, the control device 19 switches the second switch 17a1 from the open circuit to the closed circuit so that the output power of the fuel cell 44 can be output only from the self-supporting output terminal 16. At this time, the control device 19 repeatedly executes the program according to the flowchart of the subroutine shown in FIG. 6 every predetermined short time.

  In step S242, the control device 19 acquires the power consumption of the second load device 18 from the power sensor 17a2. In step S244, the control device 19 subtracts the power consumption of the second load device 18 from the constant output power (300 W) of the fuel cell 44 to derive surplus power of the fuel cell 44. And the control apparatus 19 adjusts the power consumption of the variable load apparatus L so that it may consume with the same electric power as a surplus electric power in step S246. That is, when surplus power is generated in the output power of the fuel cell 44, the control device 19 adjusts the power consumption of the variable load device L to consume the surplus power, and the output power with a constant output power ( Control is performed so as to be constant to the above-described first power amount or second power amount described later (surplus power adjustment unit).

  The control device 19 repeats the determination of “NO” in step S114 until the power consumption of the second load device 18 reaches the third power amount (50 W), and is constant at the first power amount described above. The power generation of the fuel cell 44 with the output power of is continued. On the other hand, when the power consumption of the second load device 18 exceeds the third power amount (50 W), the control device 19 determines “YES” in step S114, and increases the upper limit of the output power in step S116. Start.

The third power amount is a difference between a second power amount and a first power amount which will be described later. As described above, the first power amount is the power amount (300 W in the present embodiment) corresponding to the maximum power consumption of the variable load device L. The second power amount is a value larger than the first power amount, and is the maximum output power (for example, 350 W) during the self-sustaining power generation operation of the fuel cell 44.
In step S114, the control device 19 determines whether or not the power consumption of the second load device 18 detected by the power sensor 17a2 is larger than the third power amount.

In step S116, the control device 19 basically performs the same process as in step S108 described above.
Similarly to step S202 described above, the control device 19 increases the output power of the fuel cell 44 from the first power amount to the second power amount during the self-sustaining power generation operation after the self-sustained preparation operation is completed. When increasing, it is variable so that the total power consumption of the second load device 18 (load device during the self-sustaining operation) to which output power is supplied only during the self-sustaining power generation operation and the variable load device L is increased at the second predetermined speed. The load device L is controlled (second variable load device control unit).

  Specifically, the control device 19 acquires the power consumption of the second load device 18 from the power sensor 17a2, calculates the difference between the time change of the power consumption of the second load device 18 and the second predetermined speed, The difference is adjusted by the variable load device L. The second predetermined speed is set in the same manner as the first predetermined speed, and may be the same as the first predetermined speed or may be faster or slower.

As in step S204 described above, the control device 19 increases the total power consumption controlled by the second variable load device control unit to the output current value detected by the current sensor 11a1 (the second power supply). From a value obtained by adding an offset value α (reference offset value α0) corresponding to a predetermined speed) and a map (FIG. 7) or a relational expression showing the relationship between the input amount of raw fuel and the output current of the fuel cell A raw fuel input amount A supplied by the raw material pump 52a (raw fuel supply device) is derived (second raw fuel input amount deriving unit).
In addition, what is necessary is just to derive | lead-out each input amount of reforming steam and reaction air similarly to the input amount of raw fuel. At this time, the respective maps corresponding to FIG. 7 may be used for the input amounts of reformed steam and reaction air.
Similarly to step S206 described above, the control device 19 controls the raw material pump 52a so that the raw fuel input amount A derived by the second raw fuel input amount deriving unit is obtained.

The control device 19 repeats the determination of “NO” in step S118 until the output power of the fuel cell 44 reaches the second power amount (350 W), and continues the above-described increase control of the output power. On the other hand, when the output power of the fuel cell 44 exceeds the second power amount (350 W), the control device 19 determines “YES” in step S118, and starts a self-sustained steady-state power generation operation in step S120. In step S118, the output power may be detected or calculated in the same manner as in step S110.
In step S120, the control device 19 completes the increase control of the output power, controls the fuel cell 44 to have a constant output power (for example, 350 W), and starts self-sustained steady-state power generation. Self-sustained steady power generation is to generate power at the maximum output power during the self-sustaining power generation operation of the fuel cell 44.
Note that when the power consumption of the second load device 18 decreases, the control device 19 switches the output power of the fuel cell 44 from the second power amount to the first power amount.

  The control device 19 repeats the determination of “NO” in step S122 until the power recovery of the system power supply 30 is detected during the autonomous steady power generation, and continues the autonomous stationary power generation described above. On the other hand, when power recovery of the system power supply 30 is detected, the control device 19 determines “YES” in step S122, ends the self-sustaining power generation operation in step S124, and starts the above-described normal power generation operation in step S126. To do. In step S122, when the voltage of the system power source 30 detected by the voltage sensor 100a is equal to or higher than a predetermined voltage (for example, 9/10 or higher of the rating), it is determined that the system power source 30 has recovered. In Steps S114 and 118, power recovery is detected in the same manner as in Step S122. When power recovery is detected, the self-sustaining power generation operation is terminated and the normal power generation operation is started.

  Further, the control device 19 may execute a program according to the flowchart of the subroutine shown in FIG. 9 instead of the subroutine shown in FIG. In the subroutine shown in FIG. 9, the reference offset value α0 is corrected using the correction offset value α1 obtained by correcting the reference offset value α0 based on at least one of the temperature of the fuel cell module 40 and the accumulated operation time of the fuel cell 44. Yes.

Specifically, processing from step S222 to step S230 is performed between step S214 and step S216 shown in FIG.
In step S222, the control device 19 obtains the temperature in the fuel cell module 40 detected (and stored thereafter) by the temperature sensor 41b and the temperature at the time of the occurrence of a power failure (or when the autonomous operation starts). Instead of the temperature in the fuel cell module 40, the temperature of the fuel cell 44 may be acquired from the temperature sensor 44d.

  In step S224, the control device 19 calculates the temperature correction value from the map (FIG. 10) showing the correlation between the temperature in the fuel cell module 40 stored in advance and the temperature correction value, and the temperature acquired in step S222. β1 is calculated. Specifically, the temperature correction value β1 corresponding to the difference between the temperature acquired using FIG. 10 and the reference temperature Tn is calculated. For example, when the acquired temperature is Tn + 1 higher than the reference temperature Tn by ΔT, the temperature correction value is + β1a, and when the acquired temperature is Tn-1 lower than the reference temperature Tn by ΔT, the temperature correction is performed. The value is -β1a. The reference temperature Tn is a temperature corresponding to the reference offset value α0.

  The map shown in FIG. 10 can be calculated from the map that is the relationship between the internal resistance of the fuel cell 44 and the temperature in the fuel cell module 40 shown in FIG. The internal resistance of the fuel cell 44 and the temperature in the fuel cell module 40 are in an inversely proportional relationship that the internal resistance decreases as the temperature in the fuel cell module 40 increases. For example, a reference resistance value rn at the reference temperature Tn, a resistance rn + 1 larger than the reference resistance value rn at the temperature Tn-1, and a resistance rn-1 smaller than the reference resistance value rn at the temperature Tn + 1. is there.

In step S226, the control device 19 calculates the accumulated operation time of the fuel cell 44. Specifically, the operation time from when the fuel cell system is installed to the present time is integrated.
In step S228, the control device 19 calculates the temperature from the map (FIG. 12) showing the correlation between the accumulated operation time of the fuel cell 44 stored in advance and the temperature correction value, and the accumulated operation time calculated in step S226. The correction value β2 is calculated. Specifically, an operation time correction value β2 corresponding to the accumulated operation time is calculated using FIG. For example, when the accumulated operation time is TMn, the operation time correction value is β2b, and when the accumulated operation time is TMn + 1 longer than TMn, the operation time correction value is β2a (less than β2b). The accumulated operation time corresponding to the reference offset value α0 is 0 hour.

  The map shown in FIG. 12 can be calculated from the map that is the relationship between the internal resistance of the fuel cell 44 and the accumulated operation time shown in FIG. The internal resistance of the fuel cell 44 and the integrated operation time are in a directly proportional relationship that the internal resistance increases as the integrated operation time increases. For example, when the accumulated operation time is 0, the reference resistance value is obtained, when TMn is obtained, the resistance value is rn, and when TMn + 1 is obtained, the resistance value is rn + 1.

  In step S230, the control device 19 calculates the correction offset value α1 by correcting the reference offset value α0 with the temperature correction value β1 and the operation time correction value β2. In step S216, the correction offset value α1 calculated in step S230 is added to the output current value I acquired in step S212.

  Furthermore, an example of the operation of the fuel cell system by the control described above will be described with reference to FIG. The output power of the fuel cell 44 is indicated by a solid line, and the power consumption of the second load device 18 is indicated by a shaded portion. Independent power generation operation is started from time t1. From the time t1 until the output power of the fuel cell 44 reaches the first power amount (300 W) (time t2), the self-supporting preparation operation is performed as described above.

Specifically, the variable load device L is controlled to increase the power consumption of the variable load device L at a first predetermined speed. A value obtained by adding an offset value α (reference offset value α0) corresponding to an increase in power consumption of the variable load device L (the first predetermined speed) to the output current value detected by the current sensor 11a1; The raw fuel input amount A supplied by the raw material pump 52a is derived from a map or relational expression showing the relationship between the input amount of raw fuel and the output current of the fuel cell 44. And the raw material pump 52a is controlled so that it may become raw fuel input amount A1.
Thus, the output power of the fuel cell 44 is consumed only by the variable load device L during the period from time t1 to time t2.

  Then, at time t2, the self-supporting preparation operation is completed, and output from the fuel cell 44 is started from the self-supporting output terminal. From time t2 to time t3 when the power consumption of the second load device 18 exceeds 50 W, the output power of the fuel cell 44 is controlled to be constant to the first power amount. The surplus power of the output power of the fuel cell 44, that is, the power obtained by subtracting the power consumption of the second load device 18 from the output power of the fuel cell 44 is adjusted so as to be consumed by the variable load device L. .

  When the power consumption of the second load device 18 exceeds 50 W (time t3), the output power of the fuel cell 44 starts increasing. From the time t3 until the output power of the fuel cell 44 reaches the second power amount (350 W) (time t4), the output power of the fuel cell 44 is increased as described above.

Specifically, the variable load device L is controlled so that the total power consumption of the second load device 18 and the variable load device L is increased at a second predetermined speed. An offset value α (reference offset value α0) corresponding to an increase in the total power consumption of the second load device 18 and the variable load device L (the second predetermined speed) is added to the output current value detected by the current sensor 11a1. The raw fuel input amount A supplied by the raw material pump 52a is derived from the value obtained by adding the above and a map or relational expression showing the relationship between the input amount of the raw fuel and the output current of the fuel cell 44. And the raw material pump 52a is controlled so that it may become raw fuel input amount A1.
Thus, the output power of the fuel cell 44 is consumed by the second load device 18 and the variable load device L from time t3 to time t4.

  When the power consumption of the second load device 18 increases at time t5, the surplus power of the output power of the fuel cell 44, that is, the power obtained by subtracting the power consumption of the second load device 18 from the output power of the fuel cell 44 is variable load device. The power consumption of the variable load device L is adjusted so as to consume at L.

  According to the present embodiment, the control device 19 (first variable load device control unit) is in a self-sustaining power generation operation, and the output power of the fuel cell 44 corresponds to the maximum power consumption of the variable load device L. During the self-supporting preparatory operation, which is the operation until the amount of electric power becomes, the variable load device L is controlled so as to increase the power consumption of the variable load device L at the first predetermined speed (step S202). The control device 19 (first raw fuel input amount deriving unit) increases the power consumption of the variable load device L controlled by the first variable load device control unit to the output current value detected by the current sensor 11a1. Is supplied by the raw material pump 52a (raw fuel supply device) from the value obtained by adding the offset value α corresponding to the above and a map or relational expression showing the relationship between the input amount of the raw fuel and the output current of the fuel cell 44. The raw fuel input amount is derived (step S204). Then, the first raw fuel supply control unit controls the raw material pump 52a (raw fuel supply device) so that the supply amount of the raw fuel becomes the raw fuel input amount derived by the first raw fuel input amount deriving unit. Control. As a result, during the self-sustaining preparation operation, the variable load device L that is the consumption destination of the output power of the fuel cell 44 is raised at a predetermined speed, and the fuel is increased at a rate corresponding to the increase in the power consumption of the variable load device L. Raw fuel can be input so that the battery 44 can generate output current and thus output power. Therefore, during the self-sustaining power generation operation, the output power of the fuel cell 44 can be supplied as much as possible with respect to the necessary power consumption. Further, deterioration of the fuel cell 44 can be prevented and robustness can be ensured. In addition, thermal runaway caused by supplying a large amount of raw fuel from the beginning can be suppressed.

  In addition, the control device 19 performs the self-sustaining power generation operation when the output power of the fuel cell 44 is increased beyond the first power amount to the second power amount during the self-sustaining power generation operation after the self-sustained preparation operation is completed. The variable load device L is controlled so as to increase the total power consumption of the second load device 18 (load device during self-sustained operation) to which the output power is supplied only to and the variable load device L at a second predetermined speed. A value obtained by adding an offset value α corresponding to an increase in total power controlled by the second variable load device control unit to the output current value detected by the variable load device control unit and the current sensor 11a1. And a map or relational expression showing the relationship between the input amount of the raw fuel and the output current of the fuel cell 44, and a second raw fuel input amount derived from the raw material pump 52a (raw fuel supply device). Fuel injection The second raw fuel supply for controlling the raw material pump 52a (raw fuel supply device) so that the supply amount of the raw fuel is derived by the deriving unit and the second raw fuel input amount deriving unit. And a control unit. As a result, even during the self-sustaining power generation operation after the self-sustained preparatory operation is completed, the variable load device L that is the consumption destination of the output power of the fuel cell 44 is increased at a predetermined speed, and the power consumption of the variable load device L is increased. Raw fuel can be input so that the fuel cell 44 can generate output current and thus output power at a corresponding rate of increase. Therefore, during the self-sustaining power generation operation, the output power of the fuel cell 44 can be supplied as much as possible with respect to the necessary power consumption.

  Further, when surplus power is generated in the output power of the fuel cell 44, the control device 19 adjusts the power consumption of the variable load device L to consume the surplus power, and the output power is the first power amount or A surplus power adjustment unit (step S246) that controls the second power amount to be constant is further provided. Thereby, the output power of the fuel cell 44 can be more reliably supplied without excess or deficiency with respect to the required power consumption during the independent power generation operation.

  The control device 19 further includes a first offset setting unit (step S226-230) that corrects the offset value so as to increase as the accumulated operation time of the fuel cell 44 increases. As a result, the variable load device L that is the consumption destination of the output power of the fuel cell 44 can be increased at a predetermined speed in accordance with the length of the accumulated operation time of the fuel cell 44, and consequently the consumption of the variable load device L is increased. The raw fuel can be introduced so that the fuel cell 44 can generate the output current and hence the output power at a rate of increase corresponding to the increase in power.

  In addition, a reforming unit 43 that generates fuel from raw fuel and reforming steam, a casing 41 that has at least heat insulation that accommodates the fuel cell 44 and the reforming unit 43, and a temperature inside the casing 41 are set. And a second offset setting unit (step) for correcting the offset value so that the offset value increases as the temperature in the casing 41 detected by the temperature sensor 41b decreases. S222, 224, 230) is further provided. Thereby, the consumption destination of the output power of the fuel cell 44 according to the temperature of the casing 41 having heat insulation that accommodates at least the fuel cell 44 and the reforming unit 43 (and thus the temperature of the fuel cell 44 having a correlation). The variable load device L can be raised at a predetermined speed, so that the fuel cell can generate the output current and thus the output power at an increase rate corresponding to the increase in power consumption of the variable load device L. Can be inserted.

  In the above-described embodiment, the output voltage of the fuel cell 44 is constant, but it may be controlled using the current-voltage characteristics of the fuel cell 44. The current-voltage characteristic of the fuel cell 44 has a relationship that the voltage decreases as the current increases. According to this, it is possible to calculate the current more accurately and control the raw fuel input amount more accurately.

  In the embodiment described above, the input amount of raw fuel is derived, but the input amount of reforming water and the input amount of oxidant gas are derived and supplied in the same manner as the input amount of raw fuel. The amount may be controlled. This is because the input amount of raw fuel has a good correlation with the input amount of reforming water and the input amount of oxidant gas. According to this, similarly to the raw fuel input amount, the reforming water input amount and the oxidant gas input amount are supplied as much as possible with the output power of the fuel cell 44 as much as possible during the self-sustaining power generation operation. can do. Further, deterioration of the fuel cell 44 can be prevented and robustness can be ensured.

Further, although the fuel cell 44 in the above-described embodiment is a solid oxide fuel cell, the present invention may be applied to a polymer electrolyte fuel cell. In this case, the generator 11a is mainly composed of a fuel cell 71a and a reformer 71b as shown in FIG.
The fuel cell 71a is supplied with a fuel gas (hydrogen gas) and an oxidant gas (air containing oxygen), generates electric power through a chemical reaction between hydrogen and oxygen, and outputs a direct current (for example, 40 V).
The reformer 71b steam-reforms the fuel (reforming fuel) and supplies a hydrogen-rich reformed gas to the fuel cell 71a. The reformer 71b is a burner (combustion unit) 71b1, a reforming unit 71b2, and a monoxide. It consists of a carbon shift reaction part (hereinafter referred to as CO shift part) 71b3 and a carbon monoxide selective oxidation reaction part (hereinafter referred to as CO selective oxidation part) 71b4. Examples of the fuel include natural gas, LPG, kerosene, gasoline, and methanol.
The burner 71b1 is supplied with combustion fuel and combustion air from the outside during start-up operation, or anode off-gas (reformed gas discharged without being supplied to the fuel cell 71a) from the fuel electrode of the fuel cell 71a during steady operation. The supplied combustible gas is combusted and the combustion gas is led to the reforming unit 71b2.

The reforming unit 71b2 reforms a mixed gas obtained by mixing the fuel supplied from the outside with water vapor (reformed water) from the evaporator by using a catalyst charged in the reforming unit 71b2, and hydrogen gas and carbon monoxide gas. (So-called steam reforming reaction). At the same time, carbon monoxide and steam generated by the steam reforming reaction are converted into hydrogen gas and carbon dioxide (so-called carbon monoxide shift reaction). These generated gases (so-called reformed gas) are led to the CO shift unit 71b3.
The CO shift unit 71b3 is converted into hydrogen gas and carbon dioxide by reacting carbon monoxide and water vapor contained in the reformed gas with a catalyst filled therein. Thus, the reformed gas is led to the CO selective oxidation unit 71b4 with the carbon monoxide concentration reduced.
The CO selective oxidation unit 71b4 generates carbon dioxide by reacting carbon monoxide remaining in the reformed gas with CO purification air further supplied from the outside using a catalyst filled therein. . As a result, the reformed gas is further reduced in carbon monoxide concentration (10 ppm or less) and is led to the fuel electrode of the fuel cell 71a.

  Further, as another embodiment of the fuel cell system according to the present invention, an embodiment in which the self-supporting output terminal 16 is omitted is also conceivable. In this case, the second load device 18 is always directly connected to the second switch 17a1 even when there is power transmission from the system power supply 30 or a power failure. When there is power transmission from the system power supply 30, the second switch 17 a 1 is opened, so that no power is supplied to the second load device 18. On the other hand, since the second switch 17a1 is closed during a self-sustained power generation operation in the event of a power failure, only the power from the generator 11a is automatically supplied to the second load device 18 regardless of the user. It will be.

DESCRIPTION OF SYMBOLS 10 ... Power generation unit, 11 ... Power generation apparatus, 11a ... Generator, 41 ... Housing, 41b ... Temperature sensor, 43 ... Reformer, 44 ... Fuel cell, 11b ... Power converter, 11b1 ... Current sensor, 14 ... Transmission line , 14c ... 1st switch, 15 ... 1st load device, 17a ... Power transmission line, 17a1 ... 2nd switch, 18 ... 2nd load device, 19 ... Fuel cell control device (1st and 2nd load device control) , First and second raw fuel input amount derivation unit, first and second raw fuel supply control unit, surplus power adjustment unit, first and second offset correction unit), 20... Hot water storage unit, 21. Hot water storage tank, 22 ... Hot water tank control device, 24 ... Hot water circulation circuit, 25 ... Heat exchanger, 25a ... Casing, 27 ... Hot water tank control remote control, 30 ... System power supply, 31 ... Power line, 31a ... Current sensor, 46a1, 46a2 ... ignition Motor, 48b ... combustion catalyst heater, 100a ... voltage sensor, L ... variable load device.

Claims (5)

A fuel cell that generates electricity using fuel and oxidant gas;
A current sensor for detecting an output current of the fuel cell;
When the power transmission of the system power supply is stopped and during the self-sustaining power generation operation that generates power from the fuel cell separated from the system power supply, only the output power from the fuel cell is supplied and the power consumption is variable. A fuel cell system comprising a variable load device that can be controlled,
A raw fuel supply device for supplying raw fuel as a raw material of the fuel to the fuel cell system;
A control device for controlling the fuel cell system,
The controller is
During the self-sustaining power generation operation and during the self-sustained preparatory operation that is an operation until the output power of the fuel cell reaches the first power amount corresponding to the maximum power consumption of the variable load device, the variable A first variable load device controller that controls the variable load device to increase the power consumption of the load device at a first predetermined speed;
A value obtained by adding an offset value corresponding to an increase in power consumption of the variable load device controlled by the first variable load device controller to the output current value detected by the current sensor; A first raw fuel input amount deriving unit for deriving a raw fuel input amount supplied by the raw fuel supply device from a map or a relational expression showing a relationship between a fuel input amount and an output current of the fuel cell;
A first raw fuel supply control unit that controls the raw fuel supply device so that a supply amount of the raw fuel becomes the raw fuel input amount derived by the first raw fuel input amount deriving unit;
A fuel cell system comprising: The controller is
When the output power of the fuel cell is increased beyond the first power amount to the second power amount during the self-sustaining power generation operation after the self-sustained preparatory operation is completed, the output is performed only during the self-sustained power generation operation. A second variable load device controller that controls the variable load device so as to increase the total power consumption of the load device and the variable load device to which electric power is supplied at a second predetermined speed;
A value obtained by adding an offset value corresponding to an increase in the total power consumption controlled by the second variable load device control unit to the output current value detected by the current sensor, and input of the raw fuel A second raw fuel input amount deriving unit for deriving the raw fuel input amount supplied by the raw fuel supply device from a map or a relational expression showing the relationship between the amount and the output current of the fuel cell;
A second raw fuel supply control unit that controls the raw fuel supply device so that the supply amount of the raw fuel becomes the raw fuel input amount derived by the second raw fuel input amount deriving unit;
A fuel cell system according to claim 1 comprising:   When surplus power is generated in the output power of the fuel cell, the control device adjusts the power consumption of the variable load device to consume the surplus power, and the output power is the first power amount. The fuel cell system according to claim 1 or 2, further comprising a surplus power adjustment unit that controls the second electric energy to be constant.   4. The control device according to claim 1, further comprising a first offset setting unit that corrects the offset value so that the accumulated operation time of the fuel cell increases. 5. Fuel cell system. A reforming section for producing the fuel from the raw fuel and reforming steam;
A housing having at least heat insulation for housing the fuel cell and the reforming unit;
A temperature sensor for detecting the temperature in the housing;
Further comprising
5. The control device according to claim 1, further comprising: a second offset setting unit that corrects the offset value so that the offset value increases as the temperature in the housing detected by the temperature sensor decreases. A fuel cell system according to claim 1.

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