JP2007280790A - Fuel cell co-generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell co-generation system in which a standby power during the period, in which fuel cell cogeneration system operation is stopped is decreased. <P>SOLUTION: The fuel cell cogeneration system is provided with electric units composed of a control circuit which operates by receiving power supply, even if an inverter is not in operation, a first drive circuit group which does not need power supply during the time the inverter is not in use, and a second drive circuit group which needs power supply, even if the inverter is not in use. The control circuit outputs to the first drive circuit group a signal for stopping power supply, during the time the inverter is not in use and outputs to the second drive circuit group a signal to supply power, even if the inverter is not in use, and outputs to both the first and second drive circuit groups signals for stopping power supplies, under the condition that all the electrical units be completely stopped. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell cogeneration system, and more particularly to a technique for reducing standby power during a period in which the cogeneration system stops power generation.

  In recent years, development of a fuel cell cogeneration system has been promoted in which power generation is performed using a fuel cell and hot water can be supplied using heat generated in the power generation process. In a cogeneration system that uses a fuel cell, hydrocarbon gas such as natural gas, LPG, or butane supplied from outside is used as a raw material gas, and this is heated in a steam atmosphere in a reformer to be rich in hydrogen. The reformed gas is generated first. Next, the generated reformed gas is supplied to the fuel cell together with an oxidizing gas such as air, and DC power is generated by an electrochemical reaction. The generated DC power is usually converted into AC power having a commercial frequency by an inverter, and is connected to a commercial power system and supplied to an external power load.

  The fuel cell cogeneration system is a system that not only generates power using a fuel cell, but also makes effective use of exhaust heat generated in the process of generating reformed gas and exhaust heat generated in the process of direct current power generation in the fuel cell. is there. Specifically, hot water is generated from waste heat using a heat exchanger, and supplied to an external heat load for hot water supply in a kitchen or room heating via a hot water storage tank. The fuel cell cogeneration system is an effective system that has a very high overall energy utilization efficiency because the exhaust heat energy generated in the power generation process is recovered and effectively used in the form of hot water.

  However, the fuel cell cogeneration system is rarely operated continuously for 24 hours, and power generation may be stopped from the viewpoint of overall thermal efficiency when the demand for hot water for hot water supply or heating decreases. By the way, the fuel cell cogeneration system requires various standby powers depending on how the system is stopped even during a power generation stop period during which power generation is not being performed. When the standby power is large, the overall thermal efficiency of the system including the power generation stop period decreases.

Conventionally, the development of a fuel cell cogeneration system has focused on improving the thermal efficiency during power generation, and has not paid much attention to reducing standby power while power generation is stopped. Patent Document 1 proposes a system that reduces surplus power generated when a user goes out and is absent. However, this technology aims to reduce surplus power while power generation continues, and does not reduce standby power during a power generation stop period.
No. 2004-311409

  The present invention has been made to solve such problems of the prior art, and its object is to provide a technique for reducing standby power during a period when power generation of the fuel cell cogeneration system is stopped. It is in.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to converting the DC power generated by the fuel cell into AC power by the inverter (4) and supplying the AC power to the commercial power system (5). A fuel cell cogeneration system that supplies hot water generated by using generated heat to a load through a hot water storage tank (10), the system receiving power from a commercial power system when the operation of the inverter is stopped The power usage equipment in the system includes a control circuit (14) that operates by receiving power supply throughout the stop period of the inverter and a non-operating period during the stop period of the inverter. The drive circuit group (15) is divided into a second drive circuit group (16) having a period of operation even during an inverter stop period, and the control circuit Power is supplied from the output line (18) or input line (25) of the inverter connected to the commercial power system, and the first and second drive circuit groups are the output line of the inverter or the input line (25 of the inverter). ) Or both of these lines, and the first drive circuit group is powered off by the output signal of the control circuit during the stop period of the inverter, Even when the second drive circuit group is in the stop period of the inverter, the power supply is continued by the output signal of the control circuit during the operation period of the second drive circuit group. In a state where the used equipment may be completely stopped, the first and second drive circuit groups are configured such that the power supply is stopped by the output signal of the control circuit. A battery cogeneration system.

  In this configuration, a large number of drive circuits are divided into two drive circuit groups corresponding to the necessity of electric power according to the operation state, and the power supply to these drive circuit groups is comprehensively controlled by the control circuit. In the control, the operation state is taken into consideration, and the power supply to the drive circuit group which is not necessary for the operation is stopped at a time so that the standby power is completely zero. Therefore, there is an effect that unnecessary standby power can be greatly reduced.

  The invention according to claim 2 is the fuel cell cogeneration system according to claim 1, wherein the system includes a hot water storage amount detection sensor (20) for detecting a hot water storage amount in the hot water storage tank, and the control. When the hot water storage amount detection sensor detects that the hot water storage amount in the hot water tank has reached a predetermined amount, the circuit stops the inverter and causes the system excluding the control circuit to go to a complete stop. During the cool-down operation, a signal for stopping power supply is output to the first drive circuit group, and a signal for continuing power supply is output to the second drive circuit group. When the down operation is finished and the system excluding the control circuit can be completely stopped, a signal for stopping the power supply is output to the first and second drive circuit groups. It is a fuel cell cogeneration system, characterized in that are configured to so that.

  When the hot water tank is full of hot water, it is not possible to recover the exhaust heat in the heat exchanger, so it is necessary to stop the power generation by the fuel cell. This is because in order to continue power generation, all the exhaust heat must be released into the atmosphere, so that the overall thermal efficiency is significantly reduced and the benefits of the cogeneration system are lost. Therefore, when the hot water tank 10 is filled with hot water as in the above configuration, the power generation is stopped and the cool-down operation is started. During the cool-down operation, the power supply to the first drive circuit group that does not need to operate is stopped to reduce its power consumption to zero. Furthermore, when it is in a state that can be completely stopped, the power supply to the second drive circuit group is also stopped. As described above, since the power supply is collectively stopped by the output signal of the control circuit, there is an effect that unnecessary standby power can be greatly reduced.

  The invention according to claim 3 is the fuel cell cogeneration system according to claim 1 or 2, wherein a relay (R3) is provided between the inverter and a commercial power system, and the commercial power of the relay is further provided. When the system side wiring (19) operates by receiving power supply from the wiring and receives a system halt signal from the control circuit, the relay is immediately turned off and the relay is turned off after a predetermined time has elapsed. A relay control circuit (30) for returning to a conductive state is attached. When the relay is in a non-conductive state, the power supply is cut off and the operation is stopped, and then the relay is returned to a conductive state. In this case, the fuel cell cogeneration system is configured to start up upon receiving power supply and resume control of the system.

  According to such a configuration, it is possible to realize a sleep state in which the standby power of the control circuit is also zero, and the standby power of the entire system is only the power consumption of the timer for a predetermined time measurement. Therefore, standby power in the complete stop state can be further reduced. In addition, since the control circuit starts up after the sleep state is continued for the set time of the timer, it is possible to return to various operation states again by the control of the control circuit.

  According to a fourth aspect of the present invention, in the fuel cell cogeneration system according to the third aspect, the control circuit is configured such that the hot water storage amount detection sensor indicates that the hot water storage amount in the hot water storage tank has reached a predetermined amount. If detected, the operation of the inverter is stopped to perform the cool-down operation, and when the cool-down operation is completed and the system including the control circuit may be completely stopped, the relay control circuit The fuel cell cogeneration system is characterized in that the system pause signal is output.

  According to such a configuration, the standby power after the hot water tank is filled with warm water and the cool-down operation is performed to bring the system into a complete stop state can be reduced to only the power consumption of the timer. Therefore, standby power can be further reduced as compared with the case where the control circuit is operated even in the complete stop state.

  Further, the invention according to claim 5 is the fuel cell cogeneration system according to claim 3, wherein when the control circuit starts up due to the relay (R3) returning to the conductive state, the hot water storage A quantity detection sensor immediately determines whether or not the amount of hot water stored in the hot water tank has reached a predetermined amount, and if it has reached the predetermined amount, outputs the system pause signal to the relay control circuit. Is a fuel cell cogeneration system.

  If the hot water tank is still full of hot water when the relay (R3) returns to the ON state, it is necessary to return to the sleep state again without starting power generation. In the case of this configuration, the hot water storage amount can be frequently checked if the set time for maintaining the sleep state is shortened. Then, it is possible to quickly detect that the amount of stored hot water has decreased, and before the amount of stored hot water decreases too much, power generation can be started to replenish the amount of stored hot water.

  The invention according to claim 6 is the fuel cell cogeneration system according to claim 5, wherein the control circuit determines that the hot water storage amount has reached a predetermined amount in the determination of the hot water storage amount after the start-up. In such a case, the temperature of a predetermined portion such as the temperature of the catalyst and the raw material gas temperature in the system is further detected. If the temperature is not within the predetermined temperature range, the temperature of those portions is detected. The fuel cell cogeneration system is characterized by instructing adjustment means to adjust the temperature within the predetermined temperature range, and then outputting the system halt signal to the relay control circuit.

  When the sleep state continues for a long time, the temperature of the catalyst, the raw material gas, or the like may be excessively lowered, resulting in inconveniences such as a rise time longer than usual at the start of the next power generation. In order to prevent such inconveniences, it is desirable to maintain their temperatures within a certain range even in the sleep state. In the case of this configuration, if it is determined that it is necessary to return to the sleep state again after having exited the sleep state, the temperature of the catalyst, raw material gas, etc. is adjusted within a predetermined temperature range before returning to the sleep state, and then the sleep state is set. Return to. Therefore, it is possible to prevent the occurrence of a problem at the next power generation start.

  The invention according to claim 7 is the fuel cell cogeneration system according to claim 5, wherein the control circuit determines that the hot water storage amount has reached a predetermined amount in the determination of the hot water storage amount after the rising. In such a case, the pressures of the predetermined parts such as the raw material gas pressure and the reformed gas pressure in the system are further detected, and when those pressures are not within the predetermined pressure range, The fuel cell cogeneration system is characterized by instructing a pressure adjusting means to adjust the pressure within the predetermined pressure range, and then outputting the system halt signal to the relay control circuit.

  Even when the pressure of the raw material gas, the reformed gas, or the like is excessively reduced during the sleep state, a problem may occur at the start of the next power generation as in the case of the temperature decrease of the sixth aspect. Therefore, if the pressure of the raw material gas, reformed gas, etc. is adjusted within the predetermined temperature range before returning to the sleep state as in this configuration and then returned to the sleep state, a problem will occur at the next power generation start. The effect which can prevent this is produced.

  The invention according to claim 8 is the fuel cell cogeneration system according to claim 5, wherein the control circuit determines that the hot water storage amount has reached a predetermined amount in the determination of the hot water storage amount after the rising. In this case, it is further determined whether or not the outside air temperature is equal to or higher than a predetermined temperature, and if not, the circulating pump (9) for circulating hot water between the hot water storage tank and the heat exchanger (7). The fuel cell cogeneration system is characterized by instructing the drive circuit to operate the circulation pump for a predetermined time and then outputting the system halt signal to the relay control circuit.

  When the outside air temperature is below freezing point, the water in the pipe connecting the hot water storage tank and the heat exchanger may freeze during the sleep state. Therefore, if the circulation pump is operated for a predetermined time before returning to the sleep state as in this configuration, freezing during the sleep state can be prevented.

  The invention according to claim 9 is the fuel cell cogeneration system according to any one of claims 5 to 8, wherein the control circuit outputs the system halt signal to the relay control circuit. In the fuel cell cogeneration system, when a start signal for starting the system is received, the system is started without outputting the system pause signal.

  With such a configuration, it is possible to prevent returning to the sleep state without having to return to the sleep state.

The invention according to claim 10 is the fuel cell cogeneration system according to any one of claims 3 to 9, wherein the control circuit supplies the generated power to a commercial power system via the relay. When receiving a signal that informs that an abnormality has occurred in the commercial power system sometimes, it outputs a command signal that puts the relay in a non-conductive state, and when the relay control circuit receives the command signal, A fuel cell cogeneration system configured to immediately bring the relay into a non-conductive state.

  With such a configuration, the relay provided for entering the sleep state can also be used as a relay for system disconnection.

Hereinafter, examples of a fuel cell cogeneration system (hereinafter simply referred to as a cogeneration system) according to the present invention will be described by dividing them into embodiments.
(First embodiment)
FIG. 1 is a block diagram showing the configuration of the first embodiment. In the cogeneration system 1 shown in FIG. 1, the reformer 2, the fuel cell 3, and the inverter 4 constitute a power generation unit. A raw material gas such as natural gas is supplied to the reformer 2 and heated in a steam atmosphere to be converted into a hydrogen-rich reformed gas. The generated reformed gas is supplied to the fuel cell 3. In the fuel cell 3, the reformed gas and an oxidizing gas such as air supplied from the outside cause an electrochemical reaction by the action of the catalyst, and DC power is generated. The generated DC power is converted into AC power by the inverter 4 and supplied to the commercial power system 5 through the wiring breaker 12 in a grid connection.

  In the cogeneration system 1, hot water is generated using exhaust heat generated during the power generation process at the same time as power generation is performed. The exhaust heat gas generated in the power generation process in the fuel cell 3 and the exhaust heat gas generated in the reformer 2 are guided to the heat exchanger 7. The exhaust heat gas exchanges heat with circulating water passing through the circulation path 8 in the heat exchanger 7 to change cold water into hot water. The circulating water is taken out from the bottom of the hot water tank 10 by the circulation pump 9, is warmed while passing through the circulation path 8 passing through the heat exchanger 7, and returns to the hot water tank 10. Hot water accumulated in the upper part of the hot water tank 10 is supplied to a hot water supply load for hot water supply in a kitchen or room heating. The water reduced by the hot water supply is replenished with tap water.

  Next, the configuration of the control system of the system 1 will be described. In the cogeneration system 1 of the present embodiment, the control system is divided into a control circuit 14, a first drive circuit group 15, and a second drive circuit group 16 as shown in FIG.

  The control circuit 14 has a function of performing overall control of the entire cogeneration system 1 and is mainly composed of a microcomputer. Inside, a known CPU, RAM, ROM, input / output interface, a bus connecting them, and a DC power supply for them are provided. The power supply of the DC power supply device in the control circuit 14 is supplied from an output line 18 connected to the output of the inverter 4. Accordingly, not only during the inverter 4 is operating and generating power, but also when the inverter 4 is stopped and generating power is stopped, if the wiring breaker 12 is in the ON state, the commercial power system 5 supplies the commercial power source. In response to this, power is supplied to each part in the control circuit 14.

  The control circuit 14 is connected with a hot water storage amount detection sensor 20, a temperature sensor 21, a pressure sensor 22, and an outside air temperature sensor 23, which will be described later, and a system abnormality signal AL for notifying the abnormality of the commercial power system 5 is also input. Yes.

  The control circuit 14 outputs various operation command signals to the first drive circuit group 15 and the second drive circuit group 16. Since the operation command signal is output to these circuits in the form of a voltage signal or a weak current signal, the power required for outputting these signals is very small. Therefore, the power consumed by the control circuit 14 during operation is a small value.

  The first and second drive circuit groups 15 and 16 are circuit groups for driving a motor, a drive device such as a solenoid valve necessary for operating the cogeneration system 1, and an electric heating device typified by a heater. is there. For example, an inverter device that drives a motor, a relay circuit, a solenoid valve circuit, a thyristor type power adjustment device that adjusts heating power of a heater, and an inverter 4 that converts a DC voltage into a commercial AC voltage correspond to this. Furthermore, a temperature controller, a pressure controller, a flow controller, etc. are included in this.

  In the present embodiment, these various drive circuits are classified into a first drive circuit group 15 and a second drive circuit group 16. Among these, in the first drive circuit group 15, the inverter 4 that converts the DC power generated by the fuel cell 3 into commercial AC power is not operating, that is, the generated power is not supplied to the commercial power system 5. In the state, a drive circuit that does not need to supply power belongs. As drive circuits classified into the first drive circuit group 15, there are an inverter 4 itself, a circuit for driving an auxiliary heater attached in the hot water tank 10, and the like.

On the other hand, the second drive circuit group 16 includes drive circuits having a period that requires power supply even when the operation of the inverter is stopped.
There are generally four operating states of the fuel cell cogeneration system, and there are four corresponding operating periods. The first state (period) is a complete stop state (complete stop period). This complete stop state is a state in which not only the inverter 4 but also the fuel cell 3, the reformer 2, the heat exchanger 7 and the like are all stopped. Accordingly, the supply of raw material gas and air is also stopped.

  The second state (period) is a power generation preparation state (power generation preparation period). This is a state (period) from the time when the complete stop state is canceled until the power generation state where the inverter 4 is operated is called a start-up period. During this power generation preparation period, the temperature of the catalyst in the fuel cell 3, the temperature in the reformer 2, the partial supply of raw material gas and air, the temperature adjustment of those gases and air, the pressure adjustment, and the necessary cooling Various preparatory operations for power generation, such as water supply, are performed. In order to perform these preparation operations, it is necessary to operate several drive circuits. The drive circuits that need to be operated during the power generation preparation period belong to the second drive circuit group 16.

  The third state (period) is a power generation operation state (power generation operation period). During this period, the inverter 4 is operated to convert the DC power generated by the fuel cell 3 into commercial AC power and supply it to the commercial power system 5.

  The fourth state (period) is a cool-down state (cool-down period). This is a state (period) from the end of the third power generation operation state (power generation operation period) to the return to the complete stop state (complete stop period) that is the first state (period). During this period, for example, a cleanup operation such as turning the cooling fan or continuing to circulate the cooling water to return the high temperature portion to room temperature is performed. In order to perform such cleanup operation, it is necessary to operate several drive circuits. A drive circuit that needs to be operated during the cool-down period also belongs to the second drive circuit group 16.

  Thus, there are four states (periods) in the operating state (period) of the fuel cell cogeneration system. In the present embodiment, drive circuits that need to be operated in the second power generation preparation state (power generation preparation period) and the fourth cool down state (cool down period) are classified into the second drive circuit group 16. The drive circuits that do not need to be operated during these periods are classified into the first drive circuit group 15.

  In the conventional fuel cell cogeneration system, little attention has been paid to the amount of power used in the period excluding the third power generation operation period. For this reason, for example, power has been continuously supplied to the inverter 4 even in the second and third periods when the inverter 4 is not operated. The inverter includes a switching circuit that switches a large current and a control circuit that controls the operation of the switching circuit. The control circuit is configured using a microcomputer, and a power supply circuit for operating the microcomputer is also provided.

  These microcomputers and power supply circuits consume power when power is supplied even while the switching circuit stops the switching operation. However, there is no particular problem even if the microcomputer or the power supply circuit is completely stopped while the switching circuit stops the switching operation. For temperature regulators, pressure regulators, flow regulators, and thyristor type power regulators that control the heating output of the heater, unnecessary standby power is consumed if power is supplied when the regulating operation is not performed. .

  Therefore, in the cogeneration system 1 of the present embodiment, for the first drive circuit group 15, the power supply is stopped and the standby power is made zero during the period excluding the third power generation operation period in which the inverter 4 operates. Let The second drive circuit group 16 supplies power during the second power generation preparation period and the fourth cool-down period, but stops power supply and waits during the first complete stop period. Reduce power to zero.

  Such control of supply and stop of power is performed by the control circuit 14 which grasps the operation state. A specific circuit example for controlling the power supply by the output signal of the control circuit 14 is shown in FIG. In the case of this circuit example, the first and second drive circuit groups 15 and 16 are both supplied with two power supplies, alternating current and direct current. The AC power is supplied from the output line 18 of the inverter 4 and the DC power is supplied from the input line 25 of the inverter 4.

  Note that the switching circuit of the inverter 4 is usually configured by bridge-connecting switching elements connected with antiparallel diodes. Therefore, when the switching element stops the switching operation, the commercial AC voltage supplied to the output line 18 of the inverter 4 is rectified by the antiparallel diode, and the DC voltage is supplied to the input line 25 of the inverter 4. Therefore, even in a state where the operation of the inverter 4 is stopped and power generation is stopped, both the first and second drive circuit groups 15 and 16 can be supplied with DC power according to the circuit configuration of FIG.

  When the output voltage of the fuel cell 25 is too low, a direct current booster circuit may be provided between the fuel cell 25 and the inverter 4. Also in this case, the DC power required by the first and second drive circuit groups 15 and 16 is supplied from the input line 25 of the inverter 4.

  In the configuration of FIG. 1, power is supplied to the control circuit 14 from the output line 18 of the inverter 4. However, as described above, even when the inverter 4 stops switching operation, the input line 25 of the inverter 4 is connected to the direct current. Voltage is supplied. Therefore, the control circuit 14 may be configured to be supplied with power from the input line 25 of the inverter 4.

  The first and second drive circuit groups 15 and 16 have the same circuit configuration. The first drive circuit group 15 will be described. An AC power supply is provided via a relay contact R1a1 for a drive circuit that requires an AC power supply, and a DC power supply is provided via a relay contact R1a2 for a drive circuit that requires a DC power supply. Supply. Relay contacts R1a1 and R1a2 are a contacts (make contacts) of relay R1.

  The relay R1 is driven by the control circuit 14. Power for the relay R1 is supplied from the control circuit 14. When the control circuit 14 turns on the internal output transistor TR1, the relay contacts R1a1 and R1a2 are closed, and power is supplied to the drive circuits belonging to the first drive circuit group 15. When the control circuit 14 turns off the output transistor TR1, the relay contacts R1a1 and R1a2 are opened, the power supply to each drive circuit is cut off, and the power consumption (standby power) of the first drive circuit group 15 is completely achieved. It becomes zero. The operation of the second drive circuit group 16 is the same.

  Next, under the circuit configuration shown in FIGS. 1 and 2, the control circuit 14 supplies power to the first and second drive circuit groups 15 and 16 corresponding to the four operation states (operation periods). A control flow for controlling the above will be described with reference to the flow of FIG. The control flow in FIG. 3 represents a flow when the operation is started from the complete stop state.

  In the first step S1, since the cogeneration system 1 is in a complete stop state, the power supply to the first and second drive circuit groups 15 and 16 is cut off. As described above, the blocking is performed by turning off the transistors TR1 and TR2 in the control circuit 14 shown in FIG.

  In a succeeding step S2, it is checked whether or not power generation preparation can be started. The power generation preparation can be started when a power generation preparation instruction is issued by an operator from an operation panel (not shown), or when the hot water storage amount detection sensor 20 detects that the hot water storage amount in the hot water storage tank 10 has become a predetermined value or less. Judge.

  The process waits until the power generation is ready, and the process proceeds to step S3. In step S3, power is supplied to the second drive circuit group 16 in order to start the power generation preparation operation. Therefore, the transistor TR2 is turned on. Thereby, power is supplied to various drive circuits used in the power generation preparation operation. Since the power supply of the first drive circuit group 15 remains cut off, the standby power remains zero. If power is supplied to the second drive circuit group 16, the process proceeds to step S, and a preparatory operation for starting power generation as described above is executed.

  If power generation preparation is completed, it will move to step S5 and it will be checked whether a power generation operation may be started. It is determined that the power generation operation can be started when instructed by the operator from the operation panel or when it is determined that power generation can be started immediately after the completion of power generation preparation.

  If it is determined that the power generation operation can be started, the process proceeds to step S6. In step S6, power is supplied to the first drive circuit group 15 in order to start the power generation operation. Therefore, the transistor TR1 is turned on. And it moves to step S7 and a power generation operation is started.

  During the power generation operation, the process proceeds to step S8 to check whether it is necessary to proceed to the cool-down operation described above. There is a case in which the operator instructs the cool-down operation from the operation panel. In another case, the hot water storage amount detection sensor 20 may detect that the hot water storage amount in the hot water storage tank 10 has reached a predetermined value or more. When the hot water storage tank 10 is filled with hot water, the exhaust heat recovery by the heat exchanger 7 cannot be performed, so that the power generation by the fuel cell 3 cannot be continued. In order to continue power generation, it is necessary to release all the exhaust heat into the atmosphere, which will significantly reduce the overall thermal efficiency and eliminate the benefits of the cogeneration system. Therefore, when the hot water tank 10 is filled with warm water, the power generation is stopped and the cool down operation is started.

  Whether or not it is necessary to shift to the cool-down operation is also determined when it is determined in step S5 that the power generation operation cannot be started. This is because the power generation preparation operation is performed, but for some reason, the power generation operation is not performed and the cool down operation may be performed immediately.

  If it is determined that there is no need to move to the cool-down operation, the process proceeds to step S9. In step S9, it is determined whether the power generation operation is being performed. If the power generation operation is being performed, the process returns to step S7 to continue the power generation operation. If the power generation operation is not being performed, the process returns to step S5.

  If it is determined in step S8 that it is necessary to move to the cool-down operation, the process proceeds to step S10. In step S10, a cool-down operation is executed. Immediately after the start of the cool-down operation, the process proceeds to step S11 and the power supply of the first drive circuit group 15 is shut off. As a result, the standby power of the first drive circuit group 15 becomes zero.

  In a succeeding step S12, it is determined whether or not to enter a complete stop state. When it cannot enter into a complete stop state, it returns to step S10 and continues a cool-down operation. If it is in a state of entering a complete stop state, the process returns to step S1. Then, the power supply of the second drive circuit group 16 is also shut off. As a result, the standby powers of the first and second drive circuit groups 15 and 16 are both zero, and the cogeneration system 1 is completely stopped.

  As described above, in the cogeneration system 1 of the present embodiment, a large number of drive circuits are divided into two drive circuit groups corresponding to the necessity of electric power according to the operating state, and the power supply to these circuit groups is controlled by the control circuit 14. Control all at once. In the control, the operating state is taken into consideration, and the power supply to the drive circuit groups that are not necessary for the operation is cut off at a time so that the standby power is completely zero. Therefore, there is an effect that unnecessary standby power can be greatly reduced.

(Second Embodiment)
In the first embodiment, the standby power of the first and second drive circuit groups 15 and 16 during the complete stop period is zero, but the control circuit 14 is operated during the complete stop period. Therefore, a little standby power was generated. In the present embodiment, the standby power of the control circuit 14 during the complete stop period is also zero.

  FIG. 4 shows a circuit configuration of the cogeneration system 1a of the present embodiment. 4 differs from the circuit configuration of the first embodiment shown in FIG. 1 in that a relay R3 is added between the inverter 4 and the wiring breaker 12, and the operation of the relay R3 is the same. The relay control circuit 30 to be controlled is added.

  The relay control circuit 30 is supplied with single-phase AC power from between the relay R3 and the wiring breaker 12. FIG. 5 shows a specific circuit configuration example of the relay control circuit 30, which is configured using a relay that operates with a single-phase AC voltage. The purpose of the relay control circuit 30 is to stop the power supply to the control circuit 14 during the complete stop period so that the standby power is zero. Another object is to disconnect the cogeneration system 1a from the commercial power system 5 when an abnormality occurs in the commercial power system 5 while the control circuit 14 is operating.

  First, the operation during normal operation other than the complete stop period will be described. In that case, the transistors TR1 and TR2 in the control circuit 14 are both non-conductive. Since both the relays R10 and R20 in the relay control circuit 30 are not excited, the relay R4 is also not excited. Since the relay contacts R20b and R4b are both closed, the relay R3 is excited. Since the relay R3 is in an excited state, both the relay contacts R3a1 and R3a2 are in a closed state, and the cogeneration system 1a is connected to the commercial power system 5.

  An operation for stopping the power supply to the control circuit 14 from this state will be described. The time to stop the power supply to the control circuit 14 is immediately after the cogeneration system 1 enters the complete stop period. In order to stop the power supply, the control circuit 14 turns on the internal transistor TR3 to operate the relay R10. When the relay R10 is operated, the relay contact R10a1 is closed and the relay R4 is operated. As a result, the relay contact R4a1 is closed, so that the relay R4 is in a self-holding state.

  When the relay R4 is in a self-holding state, the relay contact R4b is opened and the relay R3 is de-energized, so that both the relay contacts R3a1 and R3a2 are opened and the supply of commercial power from the commercial power system 5 to the inverter 4 side is stopped. Therefore, the control circuit 14 is cut off from the power supply and stopped, and its standby power becomes zero. That is, when the control circuit 14 momentarily turns on the transistor TR3 immediately after entering the complete stop period, the relay contacts R3a1 and R3a2 are opened, and power is supplied to the circuit connected to the inverter 4 side portion from the relay contacts R3a1 and R3a2. Is completely stopped and its standby power becomes zero.

  On the other hand, when the relay R4 is in a self-holding state, the relay contact R4a2 is closed, the timer TM is excited, and the timer TM starts measuring time. That is, after the transistor TR3 is instantaneously turned on, only the timer TM operates, and the power consumption becomes standby power for the entire cogeneration system 1. The value is a very small value of about several tens of mW.

  The timer TM continues to measure time, and when the time is up, the contact TMb is opened. When the contact TMb is opened, the self-holding state of the relay R4 is released and the relay R4 is de-energized. When the relay R4 is de-energized, the relay contact R4b is closed and the relay R3 is excited. As a result, the relay contacts R3a1 and R3a2 are closed, and power is supplied from the commercial power system 5 to the inverter 4 side. As a result, the control circuit 14 also receives power supply and resumes operation.

  Thus, once the control circuit 14 turns on the transistor TR3, all the circuits except the timer TM are completely stopped, and only the timer TM continues to operate. Until the timer TM expires, the standby power of the cogeneration system 1a is only the power consumed by the timer TM. When the timer TM expires, the control circuit 14 resumes its operation, and various driving operations can be performed according to the instruction. Hereinafter, in this embodiment, a state in which only the timer TM operates and other circuits are completely stopped is referred to as a sleep state (pause state).

  An abnormality may occur in the commercial power system 5 while the cogeneration system 1a operates the inverter 4 to generate power. The transistor TR4 in the control circuit 14 and the relay R20 in the relay control circuit 30 are for disconnecting the output line 18 of the inverter 4 from the commercial power system 5 at that time. A signal AL notifying that an abnormality has occurred in the commercial power system 5 is input to the control circuit 14. When the control circuit 14 turns on the transistor TR4, the relay R20 operates and the relay R3 is de-energized. As a result, the relay contacts R3a1 and R3a2 are opened, and the output line 18 of the inverter 4 is disconnected from the commercial power system 5.

  Various conditions are conceivable for the cogeneration system 1a to enter the sleep state described above and to resume power generation after waking up from the sleep state. Next, an example will be described with reference to the control flows of FIGS. The control flow of FIGS. 6 and 7 is a modified embodiment after the start of power generation operation (steps S6 and S7) in the control flow of FIG. 3 described above.

  In Step A10 in FIG. 6, power is supplied to the first and second drive circuit groups 15 and 16 in order to start the power generation operation. Thereafter, the power generation operation is started (step A11). After starting the power generation operation, the process proceeds to step A12 to check whether a condition for stopping the power generation operation is satisfied. In the control flow of FIG. 6, the hot water storage tank 10 is filled with warm water as a stop condition for power generation operation. Unless the tank is full, the process returns to step A11 to continue the power generation operation. The control circuit 14 determines whether or not the tank is full based on a signal from the hot water storage amount detection sensor 20. Note that the power generation operation may be stopped even when the operator gives an instruction from the operation panel.

  If the condition for stopping the power generation operation is satisfied, the process proceeds to step A13 to enter the above-described cool-down operation. In the cool-down operation, the power supply of the first drive circuit group 15 that is not operated is shut off as described above, and the standby power is set to zero (step A14).

  During the cool-down operation, the check is repeated to determine whether or not the state can be completely stopped (step A15). If it is in a state of being able to move to the complete stop state (step A15: YES), the process proceeds to step A16. In step A16, the power supply of the second drive circuit group 16 is shut off. As a result, both the first and second drive circuit groups 15 and 16 are turned off, and their standby power becomes zero.

  However, in this state, power is supplied to the control circuit 14, and a little standby power is consumed. Therefore, in order to eliminate the standby power, the control circuit 14 turns on the transistor TR3 (step A17). Steps B1 to B6 following step A17 in the control flow of FIG. 6 describe the operations performed by the relay control circuit 30 described above in a flow.

  When the transistor TR3 is turned on, the relay R10 operates in the order of excitation → the relay R4 is self-maintained → the relay R3 is not excited to open the relay contacts R3a1 and R3a2 (step B1). As a result, the supply of commercial power from the commercial power system 5 to the inverter 4 side is stopped. The control circuit 14 is turned off to stop its operation, and its standby power becomes zero (step B2). At the same time, the timer TM starts measuring time (step B3). The cogeneration system 1a enters the sleep state described above.

  When the sleep state continues and the timer TM eventually expires (step B4: YES), the relay contacts R3a1 and R3a2 are closed (step B5). Then, power is supplied to the control circuit 14 (step B6), and the control circuit 14 resumes operation (step A18).

  The control circuit 14 whose operation has been resumed determines whether to move to power generation preparation in step A19 of FIG. 7 or to return to the sleep state again. In the present embodiment, when the hot water storage tank 10 is not filled with warm water, the process proceeds to power generation preparation. And when the hot water storage tank 10 is full with warm water, after performing the process of step A20-A31, it is made to return to a sleep state again.

  If it is determined in step A19 that the hot water storage tank 10 is not full of hot water, the process proceeds to step A33, and power is supplied to the second drive circuit group 16. Then, the power generation preparation operation is performed (step A34), and the normal operation state is restored. If it is determined in step A19 that the hot water tank 10 is warm and full (step A19: YES), the process proceeds to step A20.

  Steps A20 to A30 describe processing to be performed before returning to the sleep state again. When the cogeneration system 1a returns to the sleep state again, the portion excluding the timer TM for the set time of the timer TM again continues the complete stop state. If such a complete stop state continues for a long time, a problem may occur in the cogeneration system 1a due to natural cooling, a decrease in outside air temperature, etc., or a problem may occur when the power generation preparation operation is started next. . The processing of steps A20 to A30 is a measure for preventing the occurrence of such problems and problems.

  In the first step A20, a temperature at a predetermined location in the cogeneration system 1a is detected, and it is checked whether the temperature is within a predetermined temperature range. The predetermined location is, for example, the temperature of the catalyst in the fuel cell 3 or the temperature of the raw material gas supplied to the reformer 2. This is because problems may occur if the temperature is too high or too low. The temperature is detected using a temperature sensor (plurality) 21. When the detected temperature is not within the predetermined temperature range predetermined for each location (step A20: NO), the power is supplied to the second drive circuit group 16 (step A21), and then the location is determined. Is instructed to start the temperature adjustment operation (step A22).

  If the temperature condition is YES in step A20, or after executing step A22, the process proceeds to step A23. In step A23, this time, a pressure at a predetermined location in the cogeneration system 1a is detected, and it is checked whether the pressure is within a predetermined pressure range. The predetermined locations are, for example, the raw material gas pressure and the reformed gas pressure in the fuel cell 3. This is because problems may occur if these pressures are too high or too low. The pressure is detected using a pressure sensor (s) 22. If the detected pressure is not within the predetermined pressure range predetermined for each location (step A23: NO), power is supplied to the second drive circuit group 16 (step A24), and then those locations are detected. Is instructed to start the temperature adjustment operation (step A25).

  If the pressure condition is YES in step A23, or after executing step A25, the process proceeds to step A26. In step A26, the outside air temperature is detected this time, and it is checked whether the temperature is equal to or higher than a predetermined temperature. This is because the water in the circulation path 8 connecting the hot water tank 10 and the heat exchanger 7 may freeze when the outside air temperature drops below freezing point. The outside air temperature is detected by the outside air temperature sensor 23. If the detected outside air temperature is not equal to or higher than the predetermined temperature (step A26: NO), power is supplied to the second drive circuit group 16 (step A27), and then the circulation pump 9 is operated for a predetermined time. The drive circuit is instructed as follows (step A28). After issuing the instruction, it is checked in step A29 whether the operation time of the circulation pump 9 has reached a predetermined time. If not reached, the process returns to step A20. If reached, the process moves to step A30, and the operation of the circulation pump 9 is stopped. Then, the process proceeds to step A31.

  In step A31, it is determined whether or not the temperature condition checked in step A20, the pressure condition checked in step A23, and the outside air temperature condition checked in step A26 are all satisfied. However, regarding the outside air temperature condition, it is considered that the outside air temperature condition is satisfied when the circulating pump 9 is operated for a predetermined time or longer even when the outside air temperature is equal to or lower than the predetermined temperature.

  If all three conditions of the predetermined temperature condition, the predetermined pressure condition, and the outside air temperature condition are satisfied (step A31: YES), the process returns to step A17. In step A17, the transistor TR3 is turned on to cause the cogeneration system 1a to enter the sleep state again. If there are unsatisfied conditions among the three conditions, the process proceeds to step A32.

  In step A32, it is checked whether an operation start signal is received from the operation panel. If the activation signal has not been received, the process returns to step A20, and the processes of steps A20 to A30 are repeated until all three conditions are satisfied. If the activation signal has been received, the process proceeds to step A33 to supply power to the second drive circuit group 16. Then, the power generation preparation operation is performed (step A34), and the normal operation state is restored.

  As described above, in the cogeneration system 1a of the present embodiment, it is possible to realize a sleep state in which the standby power of the control circuit 14 is also zero and the standby power of the entire cogeneration system 1a is only the power consumption of the timer TM. Then, when the control circuit 14 starts to operate after continuing the sleep state for the set time of the timer TM, it is determined whether to enter the sleep state again, and if necessary, the sleep state is entered again. By performing such an operation, standby power can be reduced, and the overall thermal efficiency of the cogeneration system 1a can be increased.

  In addition, when it is determined that it is necessary to return to the sleep state after leaving the sleep state, the temperature, pressure, and outside air temperature, etc. determined in advance are checked before entering the sleep state again. Then, after taking measures so as not to cause inconvenience due to a long sleep state, the sleep state is restored. Therefore, when the sleep state is canceled and the power generation preparation operation is changed to the power generation operation, no problem occurs, and the transition to the operation state is smoothly performed.

It is a lineblock diagram of cogeneration system 1 concerning a 1st embodiment of the present invention. This is a configuration example of a power supply circuit to the first and second drive circuit groups 15 and 16. It is a control flow of the control circuit 14 which concerns on 1st Embodiment. It is a block diagram of the cogeneration system 1a which concerns on 2nd Embodiment. 3 is a circuit configuration example of a relay control circuit 30. It is a control flow of the control circuit 14 which concerns on 2nd Embodiment. It is a continuation part of the control flow of the control circuit 14 which concerns on 2nd Embodiment.

Explanation of symbols

  In the drawings, 1, 1a is a fuel cell cogeneration system, 3 is a fuel cell, 4 is an inverter, 5 is a commercial power system, 9 is a circulation pump, 10 is a hot water tank, 14 is a control circuit, and 15 is a first drive circuit. Group, 16 is a second drive circuit group, 18 is an inverter output line, 20 is a hot water storage amount detection sensor, 21 is a temperature sensor, 22 is a pressure sensor, 23 is an outside air temperature sensor, 25 is an inverter input line, and 30 is a relay control. Circuit R3 represents a relay.

Claims (10)

The DC power generated by the fuel cell is converted into AC power by the inverter (4) and supplied to the commercial power system (5). At the same time, hot water generated using the heat generated in the power generation process is stored in the hot water tank (10). A fuel cell cogeneration system that supplies the load via
The system is configured to receive power supply from a commercial power system when the operation of the inverter is stopped,
The power usage equipment in the system includes a control circuit (14) that operates by receiving power supply throughout the inverter stop period, and a first drive circuit group that does not operate during the inverter stop period ( 15) and the second drive circuit group (16) having a period of operation even during the inverter stop period.
The control circuit receives power supply from the output line (18) or input line (25) of the inverter connected to the commercial power system, and the first and second drive circuit groups are the output line of the inverter or the inverter. It is configured to receive power from the input line (25) or both of them,
The first drive circuit group is powered off by the output signal of the control circuit during the inverter stop period, and the second drive circuit group is not connected to the first drive circuit group even during the inverter stop period. In the state where the power supply is continued by the output signal of the control circuit during the period in which the two drive circuit groups operate, the first and second drive circuits are in a state in which all the power-using devices except the control circuit may be completely stopped. The fuel cell cogeneration system is characterized in that the group is configured such that the power supply is stopped by the output signal of the control circuit. The fuel cell cogeneration system according to claim 1,
The system includes a hot water storage amount detection sensor (20) for detecting a hot water storage amount in the hot water storage tank,
When the hot water storage amount detection sensor detects that the hot water storage amount in the hot water storage tank reaches a predetermined amount, the control circuit cools down the system except for the control circuit by stopping the operation of the inverter. During the cool-down operation, a signal for stopping power supply is output to the first drive circuit group, and a signal for continuing power supply is output to the second drive circuit group. When the cool-down operation is finished and the system except the control circuit can be completely stopped, a signal for stopping the power supply is output to both the first and second drive circuit groups. A fuel cell cogeneration system characterized by comprising: The fuel cell cogeneration system according to claim 1 or 2,
A relay (R3) is provided between the inverter and the commercial power system,
Further, when the commercial power system side wiring (19) of the relay operates by receiving power supply from the wiring and receives a system halt signal from the control circuit, the relay is immediately turned off, and Attach a relay control circuit (30) for returning the relay to a conductive state after a lapse of time,
When the relay is in a non-conducting state, the control circuit stops operating because the power supply is cut off. After that, when the relay returns to a conducting state, the control circuit starts up upon receiving power supply and controls the system. The fuel cell cogeneration system is configured to resume the operation. The fuel cell cogeneration system according to claim 3,
When the hot water storage amount detection sensor detects that the hot water storage amount in the hot water storage tank has reached a predetermined amount, the control circuit stops the inverter and performs the cool down operation.
A fuel cell cogeneration system that outputs the system pause signal to the relay control circuit when the system including the control circuit can be completely stopped after the completion of the cool-down operation. . The fuel cell cogeneration system according to claim 3,
The control circuit immediately determines whether or not the hot water storage amount in the hot water storage tank has reached a predetermined amount by the hot water storage amount detection sensor when the relay (R3) starts up due to return to the conductive state. The fuel cell cogeneration system outputs the system pause signal to the relay control circuit when the predetermined amount is reached. The fuel cell cogeneration system according to claim 5,
When the control circuit determines that the hot water storage amount has reached a predetermined amount in the determination of the hot water storage amount after the rising, the control circuit further determines a predetermined portion such as the temperature of the catalyst in the system, the raw material gas temperature, etc. If these temperatures are not within the predetermined temperature range, the temperature adjusting means of those portions are instructed to adjust within the predetermined temperature range, and then the relay control circuit A fuel cell cogeneration system that outputs the system pause signal. The fuel cell cogeneration system according to claim 5,
When the control circuit determines that the hot water storage amount has reached a predetermined amount in the determination of the hot water storage amount after the rising, the control circuit further determines a raw material gas pressure, a reformed gas pressure, and the like in the system. When the pressures of the parts are detected and those pressures are not within the predetermined pressure range, the pressure adjusting means of those parts is instructed to adjust within the predetermined pressure range, and then the relay control circuit And outputting the system pause signal. The fuel cell cogeneration system according to claim 5,
When the control circuit determines that the hot water storage amount has reached a predetermined amount in the determination of the hot water storage amount after the rising, the control circuit further determines whether the outside air temperature is equal to or higher than the predetermined temperature, and has not reached the predetermined temperature. In such a case, the drive circuit of the circulation pump (9) for circulating hot water between the hot water tank and the heat exchanger (7) is instructed to operate the circulation pump for a predetermined time, and then the relay control circuit is connected to the relay control circuit. And outputting the system pause signal. The fuel cell cogeneration system according to any one of claims 5 to 8,
When the control circuit receives a start signal for starting the system before outputting the system stop signal to the relay control circuit, the control circuit starts the system without outputting the system stop signal. A fuel cell cogeneration system characterized by entering. The fuel cell cogeneration system according to any one of claims 3 to 9,
When the control circuit receives an input of a signal notifying that an abnormality has occurred in the commercial power system while supplying the generated power to the commercial power system via the relay, the control circuit sets the relay to a non-conductive state. Command signal to output
The fuel cell cogeneration system, wherein the relay control circuit is configured to immediately turn off the relay when receiving the command signal.

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