JP2013157189A - Energy management device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy management device capable of stably generating a power of a predetermined amount.SOLUTION: An energy management device comprises: a solid oxide type fuel cell having a fuel cell, a reformer 3 performing steam reforming, and a water supply device supplying water to the reformer 3, and that is a distributed power supply having a configuration that makes burn a fuel gas that was not used for power generation in the fuel cell; the other distributed power supply; and a control device controlling power generation amounts of the solid oxide type fuel cell and the other distributed power supply. By arbitrarily controlling a fuel utilization rate, an air utilization rate, and an S/C value by using a reduction amount per unit time of a power generation amount of the other distributed power supply, a reduced power generation amount of the distributed power supply can be compensated by an increased power generation amount of the fuel cell. Thereby, the energy management device can stably generate a power of a predetermined amount.

Description

  The present invention relates to a fuel cell and an energy management device connected to a load.

  In recent years, for example, a technique for controlling a load in each house, a distributed power source provided in each house, and the like by an energy management device (for example, Home Energy Management System) provided for each house such as a single house has been proposed. Examples of the distributed power source include power generators such as fuel cells and solar cells.

  In HEMS, it is proposed that the above-described distributed power supply is not limited to a single power generator, but a combination of a plurality of power generators such as a fuel cell and a solar power generator, for example, to supply power to the home. The electric power supplied by is generally controlled and supplied so as to follow the load (power consumption) in each house (see, for example, Patent Document 1).

JP 2010-15783 A

  By the way, in an energy management device that combines a solid oxide fuel cell (SOFC), which is known as one of the above-described distributed power sources, with another distributed power source (for example, photovoltaic power generation or wind power generation), It is controlled to generate a predetermined amount of power by combining the power generation amount of the distributed power source and the power generation amount of the solid oxide fuel cell. However, in some cases, mutual complementation is not possible, making it difficult to generate the predetermined amount of power. There was a case.

  Therefore, the present invention relates to an energy management device and an operation method capable of generating a predetermined amount of power more stably in an energy management device that is a combination of a solid oxide fuel cell and another distributed power source.

  An energy management device according to the present invention includes a fuel cell, a reformer that performs steam reforming to generate fuel gas to be supplied to the fuel cell, and a water supply for supplying water to the reformer A solid oxide fuel cell which is a distributed power source having a configuration for fueling fuel gas not used for power generation in the fuel cell, another distributed power source, and the solid oxide fuel cell A control device that controls the amount of power generation with the other distributed power source, the control device when the amount of decrease in the power generation amount per unit time of the other distributed power source is equal to or greater than a first predetermined value. , Control for reducing the fuel utilization rate in the operation of the solid oxide fuel cell, control for reducing the air utilization rate in the operation of the solid oxide fuel cell, and carbon in the fuel supplied to the reformer And supplied to the reformer Of the control to reduce the value of S / C is the molar ratio of that water, and performing at least one control.

An energy management device according to the present invention includes a fuel cell, a reformer that performs steam reforming to generate fuel gas to be supplied to the fuel cell, and a water supply for supplying water to the reformer A solid oxide fuel cell which is a distributed power source having a configuration for fueling fuel gas not used for power generation in the fuel cell, another distributed power source, and the solid oxide fuel cell A control device that controls the amount of power generation with the other distributed power source, the control device when the amount of decrease in the power generation amount per unit time of the other distributed power source is equal to or greater than a first predetermined value. , Control for reducing the fuel utilization rate in the operation of the solid oxide fuel cell, control for reducing the air utilization rate in the operation of the solid oxide fuel cell, and carbon in the fuel supplied to the reformer And supplied to the reformer Of the control to reduce the value of S / C is the molar ratio of that water, by performing at least one control, it is possible to increase the power generation amount of the solid oxide fuel cell. Therefore, an energy management device capable of complementing the decrease in the power generation amount of the distributed power supply with the increase in the power generation amount of the solid oxide fuel cell and capable of stably generating a predetermined amount of power. Can do.

1 shows an example of a fuel cell system including a solid oxide fuel cell constituting an energy management device. It is a block diagram which shows an example of the energy management apparatus of this embodiment. It is a flowchart which shows an example of the operating method of the energy management apparatus of this embodiment.

  First, a solid oxide fuel cell (hereinafter abbreviated as a fuel cell) constituting an energy management apparatus will be described with reference to FIG.

  FIG. 1 is a configuration diagram illustrating an example of a configuration of a fuel cell system including a fuel cell constituting an energy management device. The fuel cell system shown in FIG. 1 includes a power generation unit that is an example of a fuel cell, a hot water storage unit that stores hot water after heat exchange, and a circulation pipe that circulates water between these units. .

  The power generation unit shown in FIG. 1 includes a cell stack 5 formed by combining a plurality of fuel cells having a fuel electrode layer, a solid electrolyte layer, and an air electrode layer, a raw fuel supply means 1 for supplying raw fuel such as city gas, An oxygen-containing gas supply means 2 for supplying oxygen-containing gas to the fuel cells constituting the stack 5 and a reformer 3 for steam-reforming the raw fuel with the raw fuel and steam are provided. The cell stack 5 and the reformer 3 are accommodated in a storage container to constitute a fuel cell module 4 (hereinafter sometimes referred to as a module). In FIG. 1, the fuel cell module 4 is surrounded by a two-dot chain line. Yes. Although not shown in the figure, the module 4 is provided with an ignition device for burning fuel gas that has not been used in power generation.

  Further, in the power generation unit shown in FIG. 1, a circulation pipe 15 that circulates water to a heat exchanger 8 that performs heat exchange between exhaust gas (exhaust heat) generated by power generation of fuel cells constituting the cell stack 5 and water. A condensed water treatment device 9 for treating the condensed water generated by the heat exchanger 8 into pure water, and a water tank 11 for storing water (pure water) treated by the condensed water treatment device 9. The water tank 11 and the heat exchanger 8 are connected by a condensed water supply pipe 10. In addition, depending on the quality of the condensed water produced | generated by the heat exchange in the heat exchanger 8, it can also be set as the structure which does not provide the condensed water processing apparatus 9. FIG. Moreover, when the condensed water processing apparatus 9 has the function to store water, it can also be set as the structure which does not provide the water tank 11. FIG.

  The water stored in the water tank 11 is supplied to the reformer 3 by a water pump 12 provided in a water supply pipe 13 that connects the water tank 11 and the reformer 3.

Further, the power generation unit shown in FIG. 1 converts the DC power generated by the module 4 into AC power, and adjusts the supply amount of the converted electricity to the external load (power conditioner, Hereinafter, it may be abbreviated as a power converter.) 6. In addition to the outlet water temperature sensor 14 for measuring the temperature of the water (circulated water flow) provided at the outlet of the heat exchanger 8 and flowing through the outlet of the heat exchanger 8, the SOFC control device 7 is provided, and a power generation unit is configured together with a circulation pump 17 that circulates water in the circulation pipe 15. And each apparatus which comprises these electric power generation units can be set as a fuel cell with easy installation, carrying, etc. by accommodating in the exterior case mentioned later. The hot water storage unit includes a hot water storage tank 16 for storing hot water after heat exchange.

  Here, an operation method of the fuel cell system shown in FIG. 1 will be described.

  At the time of starting the fuel cell, the SOFC control device 7 operates the raw fuel supply means 1, the oxygen-containing gas supply means 2, the water pump 12, and the ignition device. At this time, since the temperature of the module 4 is low, power generation in the fuel cell and reforming reaction in the reformer 3 are not performed. The fuel gas supplied by the raw fuel supply means 1 is almost entirely burned as fuel gas not used for power generation, and the temperature of the module 4 and the reformer 3 rises due to the combustion heat. In the reformer 3, when the temperature reaches a temperature at which steam reforming is possible, steam reforming is performed, and fuel gas, which is a hydrogen-containing gas necessary for power generation of the fuel cell, is generated. The SOFC control device 7 may control the water pump 12 to operate after the reformer 3 reaches a temperature at which steam reforming is possible. When the fuel cell reaches a temperature at which power generation can be started, it starts power generation using the fuel gas generated by the reformer 3 and the oxygen-containing gas supplied from the oxygen-containing gas supply means 2. The electricity generated in the cell stack 5 is converted into alternating current by the supply power adjusting unit 6 and then supplied to an external load.

  After power generation is started in the fuel cell, the SOFC control device 7 sets the fuel utilization rate (Uf), air utilization rate (Ua), reforming, which are set in advance for efficient operation of the fuel cell. The operation of the raw fuel supply means 1, the oxygen-containing gas supply means 2, the water pump 12, etc. is controlled based on the S / C value, which is the molar ratio of carbon to water in the steam reforming in the vessel 3. .

  The fuel utilization rate mentioned here is the current calculated theoretically from the composition and flow rate of the fuel gas and the actual battery when it is assumed that all the fuel gas is consumed in the battery reaction in the fuel cell. It means the ratio to the total current output from each fuel cell in the reaction.

  In addition, the air utilization rate referred to here is the current calculated theoretically from the composition and flow rate of air, assuming that all the oxygen in the air is consumed in the battery reaction in the fuel cell. It means the ratio to the total current output from each fuel cell in the battery reaction.

  On the other hand, the exhaust gas generated with the operation of the cell stack 5 is supplied to the heat exchanger 8 and is heat-exchanged with water flowing through the circulation pipe 15. Hot water generated by heat exchange in the heat exchanger 8 flows through the circulation pipe 15 and is stored in the hot water storage tank 16. On the other hand, water contained in the exhaust gas discharged from the cell stack 5 by heat exchange in the heat exchanger 8 becomes condensed water and is supplied to the condensed water treatment device 9 through the condensed water supply pipe 10. The condensed water is converted to pure water by the condensed water treatment device 9 and supplied to the water tank 11. The water stored in the water tank 11 is supplied to the reformer 3 by the water pump 12 via the water supply pipe 13. Thus, water self-sustained operation can be performed by effectively using condensed water.

  FIG. 2 is a configuration diagram illustrating an example of the energy management apparatus according to the present embodiment. The energy management apparatus shown in FIG. 2 uses the fuel cell, which is the power generation unit shown in FIG. 1, and the distributed power supply unit having the same configuration, and uses the current generated by the fuel cell and the distributed power supply. The generated current is supplied to the distribution board via a supply power adjusting unit (power converter) provided in each unit, and a predetermined amount of current is supplied to the external load by combining these currents. For example, solar power generation or wind power generation can be used as the distributed power source.

  The distribution board is provided with a measuring unit that monitors the amount of current generated by the fuel cell and the amount of current generated by the distributed power source, and information on the amount of current measured by the measuring unit is provided. , Supplied to a control device such as HEMS. Note that the measurement unit can be provided in the distribution board or adjacent to the distribution board.

  By the way, when solar power generation or wind power generation is used as the distributed power source, the power generation amount of the distributed power source may suddenly decrease, for example, when the sun suddenly falls or when the wind power decreases. In this case, in order to supply a predetermined amount of current to the external load, it is necessary to increase the power generation amount of the fuel cell.

  However, it is difficult to suddenly increase the amount of power generation under normal operating conditions of the fuel cell, and in this case, the amount of current supplied to the external load may be insufficient.

  Therefore, the present embodiment is characterized in that when the power generation amount of the distributed power source is reduced, the control device performs control to increase the power generation amount of the fuel cell.

  For example, the control device monitors the power generation amount of the distributed power source via the measurement unit, and when the reduction amount of the power generation amount per unit time of the distributed power source becomes equal to or more than a first predetermined value, the power generation amount of the fuel cell The operation of the SOFC control device is controlled so as to perform control to increase the value.

  The first predetermined value in the amount of power generation reduction per unit time of the distributed power source can be appropriately set based on the rated power generation amount of the distributed power source, etc., for example, 10% or more of the rated power generation amount on an average per minute This can be the case when it falls.

  In this case, the control device controls to reduce the fuel utilization rate of the fuel cell, to control to reduce the air utilization rate of the fuel cell, to carbon in the fuel supplied to the reformer 3, and to the reformer 3. The operation of the SOFC control device is controlled so as to perform at least one control among the controls for reducing the S / C value which is the molar ratio of the water to be performed. In order to more quickly compensate for the decrease in the power generation amount of the distributed power source, it is preferable to perform control to reduce the fuel utilization rate of the fuel cell.

  When reducing the fuel utilization rate of the fuel cell, the SOFC control device controls the raw fuel supply means 1 to increase the amount of fuel gas supplied to the reformer 3. When the amount of raw fuel supplied from the raw fuel supply means 1 increases, the amount of fuel gas supplied from the reformer 3 to the cell stack 5 increases. Accordingly, the amount of fuel gas that has not been used for power generation increases, that is, the amount of heat of combustion increases. Here, as the amount of combustion heat increases, the temperature of the fuel cell rises. In a solid oxide fuel cell, the amount of power generation can be increased as the temperature of the fuel cell rises. Therefore, the control device performs control to increase the temperature of the fuel cell, so that the amount of power generated by the fuel cell is increased. Can be increased. In the case of reducing the fuel utilization rate, the value of S / C, which is the molar ratio of carbon in the fuel supplied to the reformer 3 to be described later and water supplied to the reformer 3, is the fuel utilization rate. It is preferable that the SOFC control device also controls the operation of the water pump 12 so as to be the same value as before the decrease.

  When the air utilization rate of the fuel cell is reduced, the SOFC control device controls the oxygen-containing gas supply means 2 to increase the amount of oxygen-containing gas supplied to the cell stack 5. When the amount of the oxygen-containing gas supplied from the oxygen-containing gas supply means 2 increases, abundant oxygen is supplied to the cell stack 5 so that the catalytic activity capability of the air electrode increases and the voltage can be increased. it can. Thereby, the power generation amount of the fuel cell can be increased.

  Furthermore, in the case where the S / C value, which is the molar ratio of the carbon in the fuel supplied to the reformer 3 and the water supplied to the reformer 3, is reduced, the SOFC control device uses the water pump 12 On the other hand, control is performed to reduce the amount of water supplied to the reformer 3. When the amount of water supplied to the reformer 3 decreases, the oxygen partial pressure difference increases in the solid electrolyte layer constituting the fuel cell, thereby increasing the OCV (open circuit voltage). In addition, the temperature of the reformer 3 and the cell stack 5 rises due to the surplus heat energy in the SOFC that was consumed to vaporize the water because the amount of water supplied to the reformer 3 decreases. To do. Thereby, the power generation amount of the fuel cell can be increased.

  That is, the control device reduces the fuel usage rate of the fuel cell and the air usage rate of the fuel cell when the reduction amount of the power generation amount per unit time of the distributed power source exceeds the first predetermined value. At least one of the control to reduce the S / C value, which is the molar ratio of the carbon in the fuel supplied to the reformer 3 and the water supplied to the reformer 3, is performed. Therefore, the power generation amount of the fuel cell can be increased, the decrease in the power generation amount of the distributed power source can be supplemented with the increase in the power generation amount of the fuel cell, and a predetermined amount of power generation can be stably performed. The energy management device can be made. A plurality of these controls can be combined as appropriate.

  For example, when reducing the fuel utilization rate, for example, when the fuel utilization rate during rated operation of the fuel cell is set in the range of 50 to 80%, it may be reduced by about 10%. Moreover, when reducing an air utilization factor, what is necessary is just to reduce about 5 to 10%, for example, when the air utilization factor at the time of rated operation of a fuel cell is set in the range of 25 to 40%. Further, when the value of S / C is lowered, for example, when the S / C at the rated operation of the fuel cell is set in the range of 2.0 to 3.0, the value is reduced by about 0.5. You can do it. These values can be set as appropriate based on the rated power generation amount of the fuel cell. The rated operation means an operation for generating a preset rated output.

  By the way, when the amount of power generation reduction per unit time of the distributed power source is further increased, control for reducing the fuel utilization rate of the fuel cell, control for reducing the air utilization rate of the fuel cell, reformer In the control for reducing the value of S / C, which is the molar ratio of the carbon in the fuel supplied to the fuel 3 and the water supplied to the reformer 3, the amount of decrease in the power generation amount of the distributed power source can be achieved with only one control. May not be supplemented by an increase in the amount of power generated by the fuel cell.

  Therefore, for example, when the amount of power generation reduction per unit time of the distributed power source becomes equal to or higher than the second predetermined value set at a value higher than the first predetermined value, the control device It is preferable to control by combining at least two of the controls.

  As a result, even when the power generation amount of the distributed power source is significantly reduced, the decrease in the power generation amount of the distributed power source can be supplemented with the increase in the power generation amount of the fuel cell. Note that the amount of decrease in the amount of power generation per unit time of the distributed power supply is set to a value that is at least higher than the first predetermined value and that is greater than or equal to the second predetermined value that is set to a value higher than the first predetermined value. For example, when the first predetermined value is reduced by 10% or more of the rated power generation on average for 1 minute, the second predetermined value is rated on average for 1 minute. This can be the case when the amount of power generation is reduced by 20% or more.

In this case, the control device controls the fuel utilization rate of the fuel cell, controls the air utilization rate of the fuel cell, carbon in the fuel supplied to the reformer 3, and the reformer 3. It is possible to combine any of the controls for lowering the value of S / C, which is the molar ratio of water supplied to. However, in order to generate a predetermined amount of power more stably, it is preferable to combine in order of control that contributes to an increase in the amount of power generation. Then, by appropriately combining two or more controls, the decrease in the power generation amount of the distributed power source can be supplemented with the increase in the power generation amount of the fuel cell, and a predetermined amount of power generation can be stably performed. It can be an energy management device.

  Further, for example, when the amount of decrease in the amount of power generation per unit time of the distributed power source becomes equal to or higher than a third predetermined value set higher than the second predetermined value, the control device performs the above control. It is preferable to control in combination.

  As a result, even if the power generation amount of the distributed power source further decreases significantly, the decrease in the power generation amount of the distributed power source can be supplemented with the increase in the power generation amount of the fuel cell. Note that the amount of decrease in the amount of power generation per unit time of the distributed power supply is set to a value that is at least higher than the second predetermined value that is greater than or equal to the third predetermined value that is set higher than the second predetermined value. For example, the first predetermined value is assumed to be 10% or less of the rated power generation amount on the average for one minute, and the second predetermined value is set to 20% of the rated power generation amount on the average for one minute. %, The third predetermined value may be a case where the average power generation amount is reduced by 30% or more of the rated power generation on average for one minute.

  An operation method in such an energy management apparatus will be described with reference to a flowchart shown in FIG.

  First, information on the power generation amount of the fuel cell and the power generation amount of the distributed power source measured by the measurement unit is transmitted to the control device. Based on the transmitted information, the control device detects whether or not the amount of power generation reduction per unit time of the distributed power source is equal to or greater than a first predetermined value (S1). If the amount of power generation reduction per unit time of the distributed power source is less than the first predetermined value, the operation is maintained as it is without changing the control (S2).

  If the amount of power generation reduction per unit time of the distributed power source is equal to or greater than the first predetermined value, whether or not the amount of power generation reduction per unit time of the distributed power source continues to be equal to or greater than the second predetermined value. Is detected (S3).

  Here, when the amount of power generation reduction per unit time of the distributed power source is less than the second predetermined value, any one of the fuel usage rate, the air usage rate, and the S / C of the fuel cell is reduced. Control is performed (S4). Thereby, the power generation amount of the fuel cell can be increased.

  On the other hand, when the amount of power generation reduction per unit time of the distributed power source is equal to or greater than the second predetermined value, the amount of power generation reduction per unit time of the distributed power source continues to be equal to or greater than the third predetermined value. Is detected (S5).

  Here, when the amount of power generation reduction per unit time of the distributed power source is less than the third predetermined value, any two of the fuel usage rate, air usage rate, and S / C of the fuel cell are reduced. Control is performed (S6). Thereby, the power generation amount of the fuel cell can be increased.

  On the other hand, when the amount of power generation reduction per unit time of the distributed power source is equal to or greater than a third predetermined value, control is performed to reduce all of the fuel utilization rate, air utilization rate, and S / C of the fuel cell ( S7). Thereby, the power generation amount of the fuel cell can be increased.

  Here, if the above-described control of S4, S6, and S7 is continued, there is a risk that the power generation efficiency of the fuel cell may be reduced or deterioration may be accelerated. Therefore, when the power generation amount of the distributed power source returns to the rated power generation amount, it is preferable to cancel each control and return the fuel cell to the control of the rated operation.

Therefore, when the above-described control of S4, S6, and S7 is performed, the amount of decrease in the power generation amount per unit time of the distributed power source is greater than or equal to the first predetermined value after a predetermined time has elapsed since the start of control. It is detected whether or not there is (S8).

  In S8, when the amount of power generation reduction per unit time of the distributed power source is equal to or more than the first predetermined value, the process returns to S5 and the flow is continued.

  Conversely, in S8, when the amount of decrease in the amount of power generation per unit time of the distributed power source is less than the first predetermined value, that is, when the amount of power generation of the distributed power source returns to the original value, the fuel utilization rate and air utilization rate of the fuel cell. Then, control is performed to restore all of the S / C (S9).

  By operating the energy management device of the present embodiment as described above, the decrease in the power generation amount of the distributed power source can be supplemented with the increase in the power generation amount of the fuel cell, and a predetermined amount of power generation can be stably performed. The energy management device can be implemented. In addition, this embodiment is not restricted to the above-mentioned example, It can change suitably.

1: Raw fuel supply means 2: Oxygen-containing gas supply means 2
3: Reformer 5: Cell stack 7: SOFC control device 12: Water pump

Claims (3)

A fuel cell, a reformer that performs steam reforming to generate fuel gas to be supplied to the fuel cell, and a water supply device for supplying water to the reformer, the fuel cell A solid oxide fuel cell that is a distributed power source having a configuration in which fuel gas that has not been used for power generation in a cell is fueled, another distributed power source, and power generation by the solid oxide fuel cell and the other distributed power source A control device for controlling the amount, the control device, when the amount of decrease in the amount of power generation per unit time of the other distributed power supply is equal to or more than a first predetermined value,
Control for reducing the fuel utilization in the operation of the solid oxide fuel cell;
Control for reducing the air utilization rate in the operation of the solid oxide fuel cell;
And at least one of the controls for reducing the S / C value, which is the molar ratio of the carbon in the fuel supplied to the reformer and the water supplied to the reformer. Energy management device. The control device, when the amount of power generation reduction per unit time of the other distributed power supply is equal to or greater than a second predetermined amount set at a value higher than the first predetermined value,
Control for reducing the fuel utilization in the operation of the solid oxide fuel cell;
Control for reducing the air utilization rate in the operation of the solid oxide fuel cell;
And controlling in combination at least two or more of the controls for lowering the S / C value, which is the molar ratio of the carbon in the fuel supplied to the reformer and the water supplied to the reformer. The energy management apparatus according to claim 1. The control device, when the amount of power generation reduction per unit time of the other distributed power supply is equal to or greater than a third predetermined amount set at a value higher than the second predetermined value,
Control for reducing the fuel utilization in the operation of the solid oxide fuel cell;
Control for reducing the air utilization rate in the operation of the solid oxide fuel cell;
And control for lowering the S / C value, which is the molar ratio of the carbon in the fuel supplied to the reformer and the water supplied to the reformer, in combination. Item 3. The energy management device according to Item 2.