JP2014191949A - Cogeneration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cogeneration apparatus capable of stably performing autonomous operation of a fuel cell power generation unit without stopping power generation by this unit.SOLUTION: Provided is a cogeneration apparatus 1 for consuming, in an electric heater 7, excess power of the generated power of a fuel cell power generation unit 4, where an autonomous operation function is configured by: a first operation in which the output power of the fuel cell power generation unit 4 is adjusted to rated maximum output power and this power is supplied to a power supply receptacle 14 and the electric heater 7; a second operation in which, when the temperature of hot water in a hot water storage tank 17 becomes equal to or higher than a prescribed temperature during the first operation, the output power of the fuel cell power generation unit 4 is adjusted to rated minimum output power and the supply of generated power to the electric heater 7 is stopped; and a third operation in which, when power consumption exceeds the generated power of the fuel cell power generation unit 4 during the second operation, the output power of the fuel cell power generation unit 4 is adjusted to rated maximum output power again.

Description

  The present invention relates to a cogeneration apparatus, and more particularly to a cogeneration apparatus including a fuel cell as a power generation unit.

  Recently, a cogeneration system using a fuel cell as a distributed power source that can be connected to a power system such as a commercial power source has been provided.

  As is well known, this type of cogeneration apparatus generates hot water using exhaust heat generated during power generation of a fuel cell, and uses a fuel cell unit equipped with a fuel cell power generation unit and exhaust heat. And a hot water storage unit having a hot water storage tank for storing hot water generated in this manner.

  In such a cogeneration apparatus using a fuel cell, the fuel cell becomes too hot unless the power generated by the fuel cell power generation unit is consumed. The thing provided with the electric heater which heats the hot and cold water of this is proposed (for example, refer patent document 1).

JP 2008-22650 A

  However, such a cogeneration apparatus has the following problems, and improvements have been desired.

  Some cogeneration apparatuses of this type have a self-sustaining operation function of generating power in a state where the fuel cell power generation unit is disconnected (disconnected) from the power system when the power system fails. The self-sustaining operation function supplies power generated by the fuel cell power generation unit to a predetermined power outlet (power outlet for self-sustained operation), and allows the power to be consumed at the power outlet. In a cogeneration system, a hot water storage unit is usually configured to receive power supply from an electric power system, so if the power system fails, the electric parts of the hot water storage unit (for example, hot water in the hot water storage tank is forced to the electric heater). When the temperature of the electric pump to circulate or the temperature of the hot water in the hot water storage tank exceeds a predetermined temperature, an electric fan for a radiator that cools, etc., does not operate. For this reason, if the surplus power of the fuel cell power generation unit is consumed by the electric heater during the self-sustaining operation, there is a problem that the temperature of the hot water in the hot water storage tank becomes too high.

  In this regard, it is conceivable to stop the power generation of the fuel cell power generation unit in order to avoid the temperature rise of the hot water in the hot water storage tank, but when the power generation is stopped, the power outlet for independent operation becomes unusable, In the state where there is no power supply from the power system, the fuel cell power generation unit cannot be restarted (specifically, the auxiliary machine that starts the fuel cell power generation unit cannot be operated), so the independent operation cannot be resumed. . Even if a storage battery is provided for the operation of the auxiliary machine, the fuel cell power generation unit takes time to start. Therefore, once power generation is stopped, it takes time to restart, and during that time, independent operation cannot be performed. There is also a problem.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a code that can stably perform independent operation without stopping the power generation of the fuel cell power generation unit. It is to provide a generation device.

  In order to achieve the above object, a cogeneration apparatus according to claim 1 of the present invention is heated by a fuel cell unit including a fuel cell power generation unit and an electric heater that operates with electric power generated by the fuel cell power generation unit. A hot water storage unit having a hot water storage tank for storing the hot water to be supplied, and supplies the electric power generated by the fuel cell power generation unit to a predetermined power outlet in a state where the connection with the power system is disconnected. In the cogeneration apparatus having a self-sustaining operation function, the self-sustaining operation function is a first operation in which the output power of the fuel cell power generation unit is set to a predetermined first power, and the generated power is supplied to the power outlet and the electric heater. During the first operation, when the temperature of the hot water in the hot water storage tank becomes equal to or higher than a predetermined temperature, the output power of the fuel cell power generation unit is lower than the first power. A second operation for stopping the supply of the generated power to the electric heater, and a power consumption exceeding the generated power of the fuel cell power generation unit during the second operation; And a third operation in which the output power of the power generation unit is set to the rated maximum output power or a predetermined third power set in the vicinity thereof.

  In the cogeneration apparatus according to claim 1, when the self-sustaining operation function is started due to a power failure or the like of the power system, the fuel cell power generation unit generates power with the predetermined first power, and the generated power is supplied to the power outlet and the electricity. Supplied to the heater (first operation). As a result, the power outlet can be used, and surplus power generated by the fuel cell power generation unit is consumed by the electric heater, and the hot water in the hot water storage tank is heated.

  When the temperature of the hot water in the hot water storage tank becomes equal to or higher than the predetermined temperature by the first operation, the fuel cell power generation unit generates power with the predetermined second power lower than the first power and supplies power to the electric heater. Stop (second operation). That is, when the hot water storage unit is not connected to the power outlet for independent operation, the temperature of the hot water in the hot water storage tank rises, and in this case, the surplus power of the fuel cell power generation unit is suppressed by this second operation, The temperature rise of the hot water in the hot water storage tank is suppressed. In this second operation, the fuel cell power generation unit continues power generation without stopping power generation.

  During the second operation, when the power consumption exceeds the generated power of the fuel cell power generation unit, the fuel cell power generation unit generates power with the rated maximum output power or a predetermined third power set in the vicinity thereof. (Third operation). That is, when the power consumption exceeds the generated power during the second operation, it can be considered that the hot water storage unit is connected to the power outlet for self-sustained operation, so that the fuel cell power generation unit generates power at the maximum capacity (or near the maximum). .

  Thus, in the cogeneration apparatus according to the first aspect, in the self-sustaining operation, the generated power of the fuel cell power generation unit is controlled according to the situation such as the temperature of hot water in the hot water storage tank and the amount of power consumption due to the electric load. Therefore, the independent operation can be continued without stopping the fuel cell power generation unit as much as possible.

  The cogeneration apparatus according to claim 2 of the present invention is characterized in that, in the cogeneration apparatus according to claim 1, the first power is set to at least the rated power consumption of the hot water storage unit.

  That is, in the cogeneration apparatus according to claim 2, at the beginning of the self-sustaining operation function, the power outlet for the self-sustaining operation is supplied with power at least equal to the rated power consumption of the hot water storage unit. The hot water storage unit can be operated reliably by connecting the power plug of the hot water storage unit to the power outlet.

  The cogeneration apparatus according to claim 3 of the present invention is the cogeneration apparatus according to claim 1, wherein the first power is set at or near the rated maximum output power of the fuel cell power generation unit. Features.

  That is, in the cogeneration apparatus according to claim 3, since the fuel cell power generation unit generates the rated maximum output power or power close thereto from the beginning of the self-sustaining operation function, the power generation of the fuel cell power generation unit can be stabilized. it can. Moreover, since the rated maximum output power or power close thereto is generated, many electric loads can be connected to the power outlet for independent operation.

  The cogeneration apparatus according to claim 4 of the present invention is the cogeneration apparatus according to any one of claims 1 to 3, wherein the second power is at least the rated minimum output power of the fuel cell power generation unit or the vicinity thereof. It is characterized by being set to.

  That is, in the cogeneration apparatus according to claim 4, when the temperature of the hot water in the hot water storage tank becomes a predetermined temperature or higher during the first operation, the fuel cell power generation unit generates power at or near the rated minimum output power. The power generation of the fuel cell power generation unit can be continued in a state where surplus power is reduced as much as possible.

  A cogeneration apparatus according to a fifth aspect of the present invention is the cogeneration apparatus according to any one of the first to fourth aspects, wherein the fuel cell unit and the hot water storage unit are connected in communication, The unit is characterized in that it generates power with the third power on condition that communication with the hot water storage unit is established.

  That is, in the cogeneration apparatus according to claim 5, since the fuel cell power generation unit generates power with the third power on condition that communication with the hot water storage unit is established, the hot water storage unit is reliably connected to the power outlet for independent operation. And the fuel cell power generation unit can generate power at the maximum capacity (or near the maximum).

  A cogeneration apparatus according to a sixth aspect of the present invention is the cogeneration apparatus according to any one of the first to fifth aspects, wherein the fuel cell power generation unit is composed of a solid oxide fuel cell. Features.

  According to the present invention, the generated power of the fuel cell power generation unit is controlled according to the situation such as the temperature of the hot water in the hot water storage tank and the amount of power consumed by the electric load, so the fuel cell power generation unit is stopped as much as possible. Independent operation can be continued without any problems.

It is a block diagram which shows an example of schematic structure of the cogeneration apparatus which concerns on this invention. It is a flowchart which shows an example of the procedure of the self-supporting operation | movement in the cogeneration apparatus. It is a block diagram which shows an example of schematic structure of other embodiment of the cogeneration apparatus. It is a flowchart which shows an example of the procedure of the independent operation in the cogeneration apparatus shown to the other embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1
FIG. 1 shows a schematic configuration of a cogeneration apparatus according to the present invention. A cogeneration apparatus 1 shown in FIG. 1 is a cogeneration apparatus that generates hot water using exhaust heat generated during power generation of a fuel cell (FC), and generates fuel by a fuel cell (not shown). A fuel cell unit (hereinafter referred to as “FC unit”) 2 provided with a battery power generation unit (hereinafter referred to as “FC power generation unit”) 4 and hot water generated by utilizing exhaust heat of the fuel cell are stored. A hot water storage unit 3 having a hot water storage tank 17 is provided as a main part.

  The FC unit 2 is a device that accommodates the FC power generation unit 4 and its peripheral devices. The FC unit 2 includes the FC power generation unit 4 and the DC power generated by the FC power generation unit 4 as a commercial power source. In addition to a power conditioner 5 that converts AC power that can be connected to the power system CP, and the like, and an FC control unit 6 that controls the FC power generation unit 4, in this embodiment, the FC power generation unit 5 generates power. An electric heater 7 is provided for heating the hot water in the hot water storage tank 17 by using surplus electric power.

  The FC power generation unit 4 is a power generation unit including a fuel cell (not shown). In the present embodiment, a solid oxide fuel cell (SOFC) is used for the FC power generation unit 4. Here, since the structure of the fuel cell is well known, a detailed description thereof will be omitted. In addition to the fuel cell main body (fuel cell stack), the FC power generation unit 4 includes peripheral devices (for example, hydrogen from the fuel gas). Auxiliary equipment such as a reformer to be taken out and an air supply device for supplying oxygen in the air to the fuel cell stack. The auxiliary equipment provided in the FC power generation unit 4 is configured to operate by receiving power supply from the power system CP when the fuel cell is started (that is, when the fuel cell is not generating power), and the fuel cell After startup (that is, when the fuel cell is generating power), it is configured to operate with the power generated by the fuel cell.

  The power conditioner 5 is a grid-connected inverter device that converts DC power generated by the FC power generation unit 4 into AC power that can be linked to the power system CP, and the DC power generated by the FC power generation unit 4 DC / DC converter 9 for boosting, DC / AC inverter 10 for converting DC power boosted by DC / DC converter 9 to AC power (for example, single-phase AC 100V / 200V) that can be linked to power system CP, The power control unit 11 that controls the converter 9 and the inverter 10 is a main part.

  Here, each of the DC / DC converter 9 and the DC / AC inverter 10 is composed of a known converter circuit and inverter circuit. Further, the power control unit 11 includes a microcomputer (not shown) as a control center, and controls the operation of each unit of the power conditioner 5 in accordance with a control program of the microcomputer. These power conditioners 5 also receive power supply from the power system CP when the fuel cell is not generating power, and operate with the power generated by the fuel cell during fuel cell power generation, as with the FC power generation unit 4 described above. Is configured to do.

  Reference numeral 12 denotes a grid interconnection relay. The grid interconnection relay 12 is configured by a relay contact that is controlled to be opened and closed by the power control unit 11, the power system CP is in a non-power failure state, and the FC power generation unit 4 is normally generating power. In other words (in other words, when the FC power generation unit 4 may be connected to the power system CP), the power control unit 11 closes (short-circuits) the system connection relay 12 so that the FC power generation unit 4 is connected to the system. It is designed to be connected. That is, at the time of grid connection, the power generated by the FC power generation unit 4 is consumed by an electric load (not shown) connected between the grid connection relay 12 and the power system CP. The generated power is adjusted so that there is no surplus power that cannot be consumed.

  When the power generation system CP is generating power normally and the power system CP has a power failure, the power control unit 11 detects this power failure and opens (opens) the grid interconnection relay 12. The FC power generation unit 4 is disconnected from the power system CP, and the power generated by the FC power generation unit 4 is supplied to the power outlet 14 for independent operation. That is, the DC power generated by the FC power generation unit 4 is converted into AC power similar to that of the power system CP by the power conditioner 5 and supplied to the power outlet 14 (self-sustaining operation function). In addition, this power outlet 14 is comprised by the plug connector for wiring in which the plug connection of the power plug 20 of the hot water storage unit 3 mentioned later is possible. Reference numeral 13 denotes a self-sustaining operation relay that is closed when the self-sustaining operation function is activated. This self-sustaining operation relay 13 is also configured to be opened and closed by the power-con control unit 11.

  The FC control unit 6 is a control device that controls the operation of the FC power generation unit 4 and includes a microcomputer (not shown) as a control center. The FC control unit 6 is configured to control the FC power generation unit 4 according to a control program of the microcomputer. Yes. That is, the power generation amount (generated power) of the FC power generation unit 4 is controlled by the FC control unit 6. The FC control unit 6 is connected to the power control unit 11 via a communication line 15 so that information can be exchanged with the power control unit 11.

  The electric heater 7 constitutes heating means for heating the hot water in the hot water storage tank 17 by using surplus power generated by the FC power generation unit 5, and the DC / DC converter 9 of the power conditioner 5. Are connected to the output side of the DC / DC converter 9 and are operated by DC power output from the DC / DC converter 9. The electric heater 7 is provided with a switch (not shown), and the power controller control unit 11 (to be described later) controls the on / off of the switch to control the operation / stop of the electric heater 7. . The electric heater 7 is provided in a hot water circulation pipe 16 provided between the lower and upper parts of the hot water storage tank 17 so as to heat the hot water in the pipe. Is operated so that the hot water taken out from the lower part of the hot water storage tank 17 can be heated and returned to the upper part of the hot water storage tank 17. The circulation pipe 16 is also provided with a heat exchanger that heats the hot water in the hot water storage tank 17 by using the exhaust heat of the fuel cell (FC power generation unit 4), although not particularly shown.

  Reference numeral 8 denotes a thermistor that constitutes temperature detection means for detecting the temperature of hot water in the hot water storage tank 17, and temperature information detected by the thermistor 8 is configured to be input to the FC controller 6. . In the present embodiment, the thermistor 8 is shown on the downstream side of the electric heater 7, that is, the position where the temperature of the hot water heated by the electric heater 7 is detected, but the thermistor 8 is a hot water storage tank. It is only necessary that the temperature of the hot water in 17 is directly or indirectly measurable, and for example, it may be provided on the upstream side of the electric heater 7 in the circulation pipe 16 and further in the hot water storage tank 17 itself.

  On the other hand, the hot water storage unit 3 is a device that accommodates the hot water storage tank 17 and its peripheral devices, and includes a hot water storage tank 17, a circulation pump 18, and a hot water storage unit controller 19 as main parts.

  As described above, the hot water storage tank 17 is a tank that stores hot water generated by using the exhaust heat of the FC power generation unit 4. In this embodiment, the hot water flowing through the circulation pipe 16 is also supplied by the electric heater 7. Since it is heated, it also functions as a tank for storing hot water heated by the electric heater 7.

  The circulation pump 18 is an electric pump that forcibly circulates hot water in the hot water storage tank 17 through the circulation pipe 16. When the circulation pump 18 operates, the hot water in the hot water storage tank 17 is sucked out from the lower part of the tank. Then, it circulates in the upper part of the tank via the electric heater 7. The hot water storage unit control unit 19 is a control device that controls each part of the hot water storage unit 3, and includes a microcomputer (not shown) as a control center. Each part of the hot water storage unit 3 (for example, the circulation pump 18) according to the control program of the microcomputer. Is configured to control. In addition to these, the hot water storage unit 3 includes, for example, a radiator (cooling means) that cools hot water in the circulation pipe 16 and an electric fan that serves as an air cooling means, although not particularly illustrated, It is comprised so that the hot water in 17 may not become more than predetermined upper limit temperature.

  The hot water storage unit 3 configured in this way is provided with a power plug 20 for the hot water storage unit, and when the power system CP is in a non-power failure state, the power plug 20 is supplied with power from the power system CP. Is connected to a plug-in connector for wiring (not shown). That is, the hot water storage unit 3 is operated by the electric power from the electric power system CP when the electric power system CP is not powered off. In the event of a power failure in the power system CP, the hot water storage unit 3 can be operated with the electric power generated by the FC power generation unit 4 by connecting the power plug 20 to the power outlet 14 as will be described later. ing.

  Next, the independent operation function in the cogeneration apparatus 1 configured as described above will be described with reference to FIG.

FIG. 2 shows the procedure of the independent operation in the cogeneration apparatus 1.
In this cogeneration apparatus 1, when the power system CP is not out of power (non-power failure) and the FC power generation unit 4 is in a normal state of generating power normally, as described above, the power control unit 11 closes the grid connection relay 12 and performs normal operation to link the power generated by the FC power generation unit 4 to the power system CP (see step S1 in FIG. 2).

  During this normal operation, the power condition controller 11 constantly (or periodically) monitors the power system CP for power outages (see step S2 in FIG. 2). This power failure monitoring is performed by, for example, monitoring the input voltage with the power control unit 11 using a voltage sensor (not shown) that monitors the input voltage from the power system CP.

  In this power failure monitoring, when the power controller 11 detects a power failure of the power system CP (Yes in step S2 in FIG. 2), the self-sustaining operation function is started. That is, first, the power control unit 11 opens the grid interconnection relay 12 to disconnect the FC power generation unit 4 from the power system CP (see step S3 in FIG. 2). As a result of this disconnection, the FC power generation unit 4 performs power generation (self-sustaining power generation) in a state disconnected from the power system CP. Therefore, the power condition control unit 11 opens the grid interconnection relay 12. The FC power generation unit 4 transmits to the FC control unit 6 that the power generation unit 4 is to generate power independently.

  Here, when the power system CP fails, the hot water storage unit 3 that receives power supply from the power system CP becomes inoperable. To operate the hot water storage unit 3 during a power failure of the power system CP, the power plug 20 is operated independently. It is necessary to replace the power outlet 14 for use (details will be described later). On the other hand, as described above, the power generated by the FC power generation unit 4 is supplied to the FC unit 2, so that the FC unit 2 continues to operate even if the power system CP fails.

  When the FC control unit 6 receives a notification from the power condition control unit 11 that the FC power generation unit 4 is going to be self-sustaining power generation, the FC control unit 6 supplies the generated power of the FC power generation unit 4 (that is, the output power of the FC power generation unit 4) to a predetermined first level. The FC power generation unit 4 is controlled to be electric power (in this embodiment, the first power is set to the rated maximum output power of the FC power generation unit or the vicinity thereof). Thereby, in the FC power generation unit 4, the power generation operation (FC maximum operation) is performed with the rated maximum output power (or the vicinity thereof) (see step S4 in FIG. 2).

  When the FC power generation unit 4 performs the maximum FC operation, the power condition control unit 11 detects it from communication with the FC control unit 6 or input power to the power conditioner 5 and closes the self-sustaining operation relay 13 to become independent. The power generated by the FC power generation unit 4 is supplied to the power outlet 14 for operation, and the self-sustaining operation is started (see step S5 in FIG. 2). During this self-sustained operation, the power controller 11 supplies surplus power that is not consumed at the power outlet 14 to the electric heater 7 so that the surplus power is consumed by the electric heater 7 (see step S6 in FIG. 2).

  At this time, when the power plug 20 of the hot water storage unit 3 is connected to the power outlet 14 for independent operation, the electric power generated by the FC power generation unit 4 is supplied to the hot water storage unit 3. That is, the circulation pump 18 is operable, and hot water heated by the electric heater 7 is forcibly circulated between the hot water storage tank 17 via the circulation pipe 16. At this time, when the heated hot water (that is, hot water in the hot water storage tank 17) rises to a predetermined upper limit temperature, the hot water storage unit control unit 19 operates the electric fan of the radiator so that the hot water in the hot water storage tank 17 reaches the upper limit temperature. Cool so as not to exceed. That is, by operating the hot water storage unit 3, the FC unit 2 can continue the self-sustaining power generation while consuming the surplus power generated by the FC power generation unit 4 with the electric heater 7.

  On the other hand, when the power plug 20 of the hot water storage unit 3 is not connected to the power outlet 14 for independent operation, the hot water storage unit 3 does not operate, and the temperature detected by the thermistor 8 gradually increases. That is, the hot water heated by the electric heater 7 stays without being forcedly circulated between the hot water storage tank 17 and the temperature detected by the thermistor 8 rises. When the detected temperature of the thermistor 8 becomes equal to or higher than a predetermined temperature T1 set in advance (Yes in step S7 in FIG. 2), the FC control unit 6 sets the output power of the FC power generation unit 4 to be higher than the first power. The FC power generation unit 4 is controlled so as to be low predetermined second power (in the present embodiment, this second power is set at or near the rated minimum output power of the FC power generation unit 4). Accordingly, the FC power generation unit 4 performs a power generation operation (FC minimum operation) with the rated minimum output power (or the vicinity thereof) (see step S8 in FIG. 2).

  When the FC power generation unit 4 performs the minimum FC operation, the power condition control unit 11 detects this from the communication with the FC control unit 6 or the input power to the power conditioner 5 and stops the power supply to the electric heater 7. . Specifically, the power controller 11 turns off the electric heater 7 and stops the power supply to the electric heater 7 (see step S9 in FIG. 2). Thereby, the temperature rise of the hot water in the hot water storage tank 17 is suppressed.

  As described above, in the cogeneration apparatus 1 shown in the present embodiment, when the power system CP is cut off and the FC power generation unit 4 performs self-sustaining power generation, the FC power generation unit 4 is first generated with the maximum power (or the vicinity thereof). The self-sustained operation is started, and the power plug 20 of the hot water storage unit 3 is connected to the power outlet 14 for the self-sustained operation even if a certain time has elapsed after the start of the self-sustained operation (even if the detected temperature of the thermistor 8 becomes T1 or higher) If not, the FC power generation unit 4 is generated with the minimum power (or the vicinity thereof), and the temperature rise of the hot water in the hot water storage tank 17 is suppressed while the power generation in the FC power generation unit 4 is continued.

  Then, as a countermeasure when the power outlet 20 of the hot water storage unit 3 is connected to the power outlet 14 for independent operation when the FC power generation unit 4 is in the minimum FC operation, the power control unit 11 is connected to the power outlet 14 during the minimum FC operation. The load power consumed by the power generator is monitored, and it is determined at all times (or periodically) whether or not this load power (power consumption) exceeds the power generated by the FC power generation unit 4 (see step S10 in FIG. 2). ).

  When the power plug 20 of the hot water storage unit 3 is connected to the power outlet 14 for independent operation and the load power exceeds the generated power of the FC power generation unit 4 (Yes in step S10 in FIG. 2), the power control unit 11 opens the self-sustained operation relay 13 to temporarily stop the self-sustained operation (see step S11 in FIG. 2), and causes the FC power generation unit 4 to send predetermined FC power to the FC control unit 6 (this third power is FC power generation). Instructed to generate power at the rated maximum output power of section 4 or in the vicinity thereof.

  Thereby, the FC control unit 6 controls the FC power generation unit 4 to generate power with the rated maximum output power (or the vicinity thereof), and the power generation operation with the rated maximum output power (or the vicinity thereof) by the FC power generation unit 4 (or the vicinity thereof). FC maximum operation) is performed (see step S4 in FIG. 2), and the independent operation is resumed (see step S5 in FIG. 2).

  Note that the load power exceeds the generated power of the FC power generation unit 4 even when the power generation outlet of the electric load other than the hot water storage unit 3 is connected to the power outlet 14 for independent operation while the FC power generation unit 4 is in the minimum FC operation. In this case (Yes in step S10 in FIG. 2), the FC power generation unit 4 performs the maximum FC operation (see step S4 in FIG. 2). In this case, the thermistor 8 is operated along with the operation of the electric heater 7. Since the detected temperature is equal to or higher than the predetermined temperature T1 (Yes in step S7 in FIG. 2), the FC power generation unit 4 performs the minimum FC operation (see step S8 in FIG. 2).

  On the other hand, as a countermeasure when the power outlet 20 of the hot water storage unit 3 is not connected to the power outlet 14 for independent operation when the FC power generator 4 is in the minimum FC operation, in this case, the load power is Since it is below the generated power (No in step S10 in FIG. 2), the FC controller 6 monitors the detected temperature of the thermistor 8, and the detected temperature is equal to or higher than the second predetermined temperature T2 set higher than the predetermined temperature T1. (See step S12 in FIG. 2), and if it is equal to or higher than the second predetermined temperature, power generation in the FC power generation unit 4 is stopped (see step S13 in FIG. 2). That is, if the rise in the temperature of hot water in the hot water storage tank 17 does not stop even after the electric heater 7 is stopped, the power generation itself of the FC power generation unit 4 is stopped.

  As described above, in the cogeneration apparatus 1 shown in the present embodiment, in the self-sustaining operation executed in response to the power failure of the power system CP, the temperature of the hot water in the hot water storage tank 17 and the amount of power consumption due to the electric load are reduced. Accordingly, since the power generation of the FC power generation unit 4 is continued as much as possible while adjusting the generated power of the FC power generation unit 4, the independent operation can be stably performed.

Embodiment 2
Next, a second embodiment of the present invention will be described with reference to FIGS.
Here, FIG. 3 shows a schematic configuration of the cogeneration apparatus 1 of the present embodiment, and FIG. 4 shows a procedure of the self-sustained operation in the cogeneration apparatus 1.

  The cogeneration apparatus 1 shown in the second embodiment is a modified example in which the FC control unit 6 and the hot water storage unit control unit 19 are communicatively connected via the communication line 21 and a part of the operation procedure of the self-sustaining operation function is changed. The other configurations are the same as those of the cogeneration apparatus 1 shown in the first embodiment. Therefore, parts having the same configuration are denoted by the same reference numerals and description thereof is omitted.

  In the cogeneration apparatus 1 shown in the present embodiment, as described above, the FC control unit 6 of the FC unit 2 and the hot water storage unit control unit 19 of the hot water storage unit 3 are communicatively connected via the communication line 21, and both control units 6, 19 are connected. Are configured to be able to communicate with each other.

  And in the cogeneration apparatus 1 of this embodiment, a self-sustained operation is performed in the following procedures.

  That is, also in this cogeneration apparatus 1, the power condition control unit 11 closes the grid interconnection relay 12 when the power system CP is in a normal state where the power system CP is not out of power and the FC power generation unit 4 is generating power normally. Thus, the normal operation for connecting the FC power generation unit 4 to the power system CP is performed (see step S1 in FIG. 4), and the power failure monitoring of the power system CP is performed (see step S2 in FIG. 4).

  When the power control unit 11 detects a power failure of the power system CP in this power failure monitoring (Yes in step S2 in FIG. 4), the power control unit 11 disconnects the FC power generation unit 4 from the power system CP (step S3 in FIG. 4). Reference), the FC control unit 6 is notified that the FC power generation unit 4 is to generate power independently.

  The FC control unit 6 that has received this notification from the power condition control unit 11 uses the generated power of the FC power generation unit 4 (that is, the output power of the FC power generation unit 4) as a predetermined first power (the first power in the present embodiment). Is set to at least the rated power consumption of the hot water storage unit 3. Specifically, for example, the rated power consumption value of the hot water storage unit 3 is set to the first power.) To do. As a result, the FC power generation unit 4 performs a power generation operation (FC hot water storage operation) with electric power capable of operating the hot water storage unit 3 at a minimum (see step S4 in FIG. 4).

  When the FC power generation unit 4 performs the FC hot water storage operation, the power condition control unit 11 detects this from the communication with the FC control unit 6 or the input power to the power conditioner 5 and closes the self-sustained operation relay 13 to become independent. The power generated by the FC power generation unit 4 is supplied to the power outlet 14 for operation to start the self-sustaining operation (see step S5 in FIG. 4). Then, during this self-sustained operation, surplus power is supplied to the electric heater 7 (see step S6 in FIG. 4).

  In this state, the power plug 20 of the hot water storage unit 3 is connected to the power outlet 14 for independent operation, the hot water storage unit 3 starts operating, and communication between the FC control unit 6 and the hot water storage unit control unit 19 starts. When this occurs (Yes in step S7 in FIG. 4), the FC control unit 6 detects the start of communication and controls the FC power generation unit 4 to generate power at the rated maximum output power (or the vicinity thereof). The unit 4 is caused to perform a power generation operation (FC maximum operation) with the rated maximum output power (or the vicinity thereof) (see step S8 in FIG. 4).

  That is, in the cogeneration apparatus 1 shown in the present embodiment, the FC power generation unit 4 is generated with the minimum power necessary for the operation of the hot water storage unit 3 at the beginning of the self-sustaining operation, and communicates with the hot water storage unit control unit 19. After confirming the start of operation of the hot water storage unit 3 by detection, the FC power generation unit 4 is configured to generate power with the maximum power (or the vicinity thereof).

  On the other hand, when the FC control unit 6 does not detect communication with the hot water storage unit control unit 19 (No in step S7 in FIG. 4), the power plug 20 of the hot water storage unit 3 is connected to the power outlet 14 for independent operation. The FC controller 6 determines that the detected temperature of the thermistor 8 is equal to or higher than the predetermined temperature T1 (see step S9 in FIG. 4), and if it is equal to or higher than the predetermined temperature T1 (step in FIG. 4). Yes in S9), the output power of the FC power generation unit 4 is a predetermined second power lower than the first power (in this embodiment, the second power is at or near the rated minimum output power of the FC power generation unit 4). The FC power generation section 4 is controlled so that the power generation operation (FC minimum operation) is performed with the rated minimum output power (or the vicinity thereof) (see step S10 in FIG. 4).

  When the FC power generation unit 4 enters the minimum FC operation, the power condition control unit 11 detects this from the communication with the FC control unit 6 or the input power to the power conditioner 5 and stops the power supply to the electric heater 7. (See step S11 in FIG. 4) to suppress the temperature rise of the hot water in the hot water storage tank 17.

  And the response | compatibility when the power outlet 20 of the hot water storage unit 3 is connected to the power outlet 14 for independent operation in the state where the FC power generation unit 4 is in the minimum FC operation is substantially the same as in the first embodiment. That is, when the load power exceeds the generated power of the FC power generation unit 4 during the FC minimum operation (Yes in step S12 in FIG. 4), the power condition control unit 11 temporarily stops the independent operation (see step S13 in FIG. 4), and the FC The power generation unit 4 generates power with the first power (see step S4 in FIG. 4), and starts a self-sustained operation with the first power (see step S5 in FIG. 4).

  On the other hand, when the power outlet 20 of the hot water storage unit 3 is not connected to the power outlet 14 for independent operation when the FC power generation unit 4 is in the minimum FC operation (No in step S12 in FIG. 4), the FC control unit 6 Then, it is determined whether or not the detected temperature of the thermistor 8 is equal to or higher than the second predetermined temperature T2 (see step S14 in FIG. 4). If the detected temperature is equal to or higher than the second predetermined temperature T2, power generation by the FC power generation unit 4 is performed. Stop (see step S15 in FIG. 4).

  Thus, also in the cogeneration apparatus 1 shown in the present embodiment, in the self-sustaining operation that is executed in response to the power failure of the power system CP, the temperature of hot water in the hot water storage tank 17 and the amount of power consumption due to the electric load, etc. Accordingly, the power generation of the FC power generation unit 4 is continued without being stopped as much as possible while adjusting the generated power of the FC power generation unit 4, so that the independent operation can be stably performed.

  The above-described embodiment shows a preferred embodiment of the present invention, and the present invention is not limited to this, and various design changes can be made within the scope of the invention.

  For example, in the above-described embodiment, the configuration in which the circulation pump 18 that forcibly circulates hot water in the circulation pipe 16 is provided on the hot water storage unit 3 side is shown. However, the circulation pump 8 only needs to be provided in the circulation pipe 16. It may be provided on the unit 2 side.

  In the above-described embodiment, the fuel cell provided in the FC power generation unit 4 is a solid oxide fuel cell (SOFC). However, the fuel cell of another aspect (for example, a solid polymer fuel cell ( PEFC)).

  Furthermore, in the above-described embodiment, the configuration in which the power outlet 14 for independent operation is provided on the FC unit 2 side is shown, but the power outlet 14 may be provided on the hot water storage unit 3 side.

1 Cogeneration system 2 Fuel cell unit (FC unit)
3 Hot water storage unit 4 Fuel cell power generation unit (FC power generation unit)
5 Power conditioner 6 FC controller 7 Electric heater 8 Thermistor 9 DC / DC converter 10 DC / AC inverter 11 Power converter controller 12 Grid connection relay 13 Self-sustaining operation relay 14 Power outlet 17 for self-sustaining operation Hot water storage tank 18 Circulation pump 19 Hot water storage unit controller 20 Power plug CP Power system

Claims (6)

A fuel cell unit including a fuel cell power generation unit, and a hot water storage unit including a hot water storage tank that stores hot water heated by an electric heater that is operated by power generated by the fuel cell power generation unit. In a cogeneration apparatus having a self-sustained operation function of supplying power generated by the fuel cell power generation unit to a predetermined power outlet in a state where the interconnection with the system is disconnected,
The autonomous operation function is
A first operation in which the output power of the fuel cell power generation unit is a predetermined first power, and the generated power is supplied to the power outlet and the electric heater;
During the first operation, when the temperature of the hot water in the hot water storage tank becomes equal to or higher than a predetermined temperature, the output power of the fuel cell power generation unit is set to a predetermined second power lower than the first power, and the generated power to the electric heater A second operation to stop the supply of
During the second operation, when the power consumption exceeds the generated power of the fuel cell power generation unit, the output power of the fuel cell power generation unit is set to the rated maximum output power or a predetermined third power set in the vicinity thereof. A third action to
A cogeneration apparatus characterized by comprising:   The cogeneration apparatus according to claim 1, wherein the first power is set to at least a rated power consumption of the hot water storage unit.   2. The cogeneration apparatus according to claim 1, wherein the first power is set at or near a rated maximum output power of the fuel cell power generation unit.   4. The cogeneration apparatus according to claim 1, wherein the second power is set to at least the rated minimum output power of the fuel cell power generation unit or the vicinity thereof. 5. The fuel cell unit and the hot water storage unit are connected for communication,
5. The cogeneration apparatus according to claim 1, wherein the fuel cell power generation unit generates power with the third power on condition that communication with the hot water storage unit is established.   The cogeneration apparatus according to any one of claims 1 to 5, wherein the fuel cell power generation unit is configured by a solid oxide fuel cell.

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