JP2025110781A - Power Generation Unit - Google Patents

Abstract

A power generation unit capable of stabilizing the output voltage of an independent outlet used during a power outage in a commercial power system is provided.
[Solution] The power generating unit (100) is operated in a parallel state or in a disconnected state to a commercial power system (500), and includes a power generating module (20), a power conditioner (16), a controller (17), an independent outlet (300) that supplies a portion of the power generated by the power generating module (20) to an electric power consuming device in the disconnected state, and load modules (40, 50) that internally consume a portion of the power generated by the power generating module (20) in the disconnected state. During operation in an independent operation mode in the disconnected state, the controller (17) adjusts the power consumption of the load modules (40, 50) so that the effective output power (Qe) of the independent outlet (300), calculated by subtracting a first power loss (Q1) due to operation of the load modules (40, 50) from the power generated by the power generating module (20), follows the power consumption (Qc) of the electric power consuming device.
[Selected Figure] Figure 2

Description

The present invention relates to a power generation unit using a fuel cell or the like.

Switching some of the commercial electricity consumers currently purchase from power companies to self-generated electricity is expected to lead to a reduction in carbon dioxide emissions. For example, while the primary energy efficiency of thermal power generation using coal or LNG as fuel is around 40%, the primary energy efficiency of solid oxide fuel cells (SOFCs), which generate electricity by reforming city gas, which is primarily composed of methane, is expected to be 50% to 65%. Therefore, increasing the proportion of self-generated electricity can contribute to reducing the environmental impact.

In addition, by realizing a system that can independently maintain power supplies during power outages caused by natural disasters, it is hoped that the negative impact on social life and economic activity can be reduced. For example, solid oxide fuel cells (SOFCs) can independently generate electricity and supply power to the outside world as long as the city gas supply is not cut off. In the case of an earthquake, depending on its scale, gas infrastructure may be damaged, but in the case of a typhoon, there is almost no impact on the gas infrastructure, so power supply can continue.

Patent Documents 1 to 3 disclose power generation units (fuel cell units) that operate in parallel with a commercial power system and supply power to power-consuming facilities. When the power generation unit is in operation, reverse power flow to the commercial power system is not permitted. Therefore, the power generation units described in Patent Documents 1 and 2 are designed to consume excess generated power using an electric heater or the like.

Furthermore, the power generation unit described in Patent Document 3 is disconnected from the commercial power system in the event of a power outage to avoid reverse power flow and switches to stand-alone operation. Since the power generation unit cannot supply power to power-consuming equipment when it is disconnected, it sends self-generated power to stand-alone outlets to which power-using devices can be connected, thereby meeting the power needs of consumers.

JP 2010-238496 A JP 2013-038052 A JP 2015-156769 A

A typical standalone outlet has multiple plug sockets so that several power-using devices can be used simultaneously, but power consumption fluctuates depending on the number of connected power-using devices. For this reason, the standalone operation power (output power) of the power generation unit is kept constant, and excess generated power is consumed by electric heaters, etc.

However, if the power consumption of an electric heater or other device is too high or too low compared to the power consumption of the power-using device, the output voltage of the independent outlet 300 may become unstable, and the power needs of the consumer may not be fully met.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a power generation unit that can stabilize the output voltage of an independent outlet used during a power outage in the commercial power system.

The power generation unit of the present invention is a power generation unit that operates in a parallel state or a disconnected state with respect to a commercial power system, and includes a power generation module operated by auxiliary equipment, a power conditioner that converts the power generated by the power generation module into output power equivalent to the AC power of the commercial power system, a controller that controls the power generation module and the auxiliary equipment, an independent outlet that supplies a portion of the power generated by the power generation module to an electric power-using device in the disconnected state, and a load module that internally consumes a portion of the power generated by the power generation module in the disconnected state. The controller and the power conditioner are configured to operate in a grid-connected operation mode in the parallel state and in an independent operation mode in the disconnected state. During operation in the independent operation mode, the controller adjusts the power consumption of the load module so that the effective output power of the independent outlet, calculated by subtracting a first power loss due to operation of the load module from the power generated by the power generation module, tracks the power consumption of the electric power-using device.

The present invention provides a power generation unit that can stabilize the output voltage of an independent outlet used during a power outage in the commercial power system.

FIG. 2 is a schematic diagram showing the configuration of a power generation unit. FIG. 1 is a schematic diagram illustrating a configuration of a power conditioner. FIG. 2 is a perspective view showing the appearance of the power generation unit. FIG. FIG. 2 is a schematic diagram showing the configuration of a power generation unit. FIG. 2 is a schematic diagram showing the configuration of a heat recovery unit.

Each embodiment of the present invention will be described below with reference to the accompanying drawings.

First Embodiment
<Outline of power generation unit configuration>
First, an outline of the configuration of a power generation unit according to the first embodiment will be described. Fig. 1 is a schematic diagram showing the configuration of a power generation unit according to the first embodiment. As shown in Fig. 1, the power generation unit 100 is a monogeneration type that uses fuel cells, and includes a plurality of cell stacks 1, a reformer 2, a burner 3, an evaporator 4, an air preheater 5, an anode off-gas cooler 6, an anode off-gas condenser 7, a CO oxidizer (carbon monoxide oxidizer) 8, a condensed water recovery tank 9, a first raw fuel blower 10, a first air blower 11, a water pump 12, a second raw fuel blower 13, a second air blower 14, a third air blower 15, a power conditioner 16, and a unit controller 17.

In this embodiment, a total of eight cell stacks 1 are provided, including those not shown in Figure 1.

The power generation unit 100 also has the following lines (pipes): a raw fuel line La, a mixed gas line Lb, an anode fuel line Lc, an anode offgas line Ld, a cathode air line Le, a cathode offgas line Lf, a combustion gas line Lg, a burner cooling air line Lh, a reforming water line Li, a startup air line Lj, a cooling air line Lk, and a condensed water recovery line Lw.

The anode fuel line Lc includes a first distribution manifold Ma, which serves as the main pipe for the anode fuel inlet, and the cathode air line Le includes a second distribution manifold Mb, which serves as the main pipe for the cathode air inlet. These distribution manifolds Ma and Mb have an inlet and multiple outlets corresponding to each cell stack 1, and allow the fluid that flows into the inlet to flow out from each of the outlets.

The anode offgas line Ld includes a first collection manifold Mc, which serves as the outlet pipe for the anode offgas, and the cathode offgas line Lf includes a second collection manifold Md, which serves as the outlet pipe for the cathode offgas. These collection manifolds Mc and Md have multiple inlets and outlets corresponding to each cell stack 1, and allow fluid that flows into each inlet to flow out from the outlet.

The combustion gas line Lg includes a heat radiation tube Za and a combustion gas pipe Zb. The cooling air line Lk includes a cooling pipe Zc and a collection pipe Lk1.

The raw fuel line La is a pipe connecting the fuel inlet E1 and the burner 3, and a second raw fuel blower 13 is disposed in this pipe. The second raw fuel blower 13 is a device that pressurizes the raw fuel gas Gf (e.g., methane-containing gas such as city gas 13A) taken in through the fuel inlet E1 and sends it downstream along the raw fuel line La, and is typically driven during start-up operation of the power generation unit 100.

The mixed gas line Lb is a pipe connecting the fuel inlet E2 and the reformer 2, and in this pipe, from upstream to downstream, are arranged the first raw fuel blower 10, the evaporator 4, and the first bellows-type expansion joint B1. The first raw fuel blower 10 is a device that pressurizes the raw fuel gas Ga taken in through the fuel inlet E2 and sends it to the downstream side of the mixed gas line Lb, and is typically driven when the power generation unit 100 is operating to generate electricity.

The anode fuel line Lc is a pipe connecting the reformer 2 and the anode of each cell stack 1. More specifically, from the upstream side, the anode fuel line Lc includes a pipe connecting the reformer 2 and the inlet of the first distribution manifold Ma, the first distribution manifold Ma, and eight pipes (branch pipes of the first distribution manifold Ma) connecting each outlet of the first distribution manifold Ma to the anode of each cell stack 1.

The anode offgas line Ld is a pipeline connecting the anode of each cell stack 1 to the burner 3. More specifically, the anode offgas line Ld has, from upstream to downstream, eight pipelines (branch pipes of the first collection manifold Mc) connecting the anode of each cell stack 1 to each inlet of the first collection manifold Mc, the first collection manifold Mc, and a pipeline (hereinafter referred to as "pipe line Ld1") connecting the outlet of the first collection manifold Mc to the burner 3. Along the pipeline Ld1, from upstream to downstream, a second bellows-type expansion joint B2, an anode offgas cooler 6, an anode offgas condenser 7, and an air-water separator Sa are arranged.

The cathode air line Le is a pipe connecting the air intake E3 to the cathode of each cell stack 1. More specifically, from the upstream side, the cathode air line Le includes a pipe (hereinafter referred to as "pipe Le1") connecting the air intake E3 to the inlet of the second distribution manifold Mb, the second distribution manifold Mb, and eight pipes (branch pipes of the second distribution manifold Mb) connecting each outlet of the second distribution manifold Mb to the cathode of each cell stack 1.

In the middle of the pipeline Le1, arranged in order from upstream to downstream are a first air blower 11, an anode off-gas cooler 6, an air preheater 5, and a third bellows-type expansion joint B3. The first air blower 11 is a device that pressurizes air Aa taken in through the air inlet E3 and sends it to the downstream side of the cathode air line Le, and is typically driven during power generation operation of the power generation unit 100. Furthermore, in the pipeline Le1, a bypass path Le2 is provided that bypasses the anode off-gas cooler 6 and the air preheater 5, connecting the midpoint between the air inlet E3 and the anode off-gas cooler 6 and the midpoint between the air preheater 5 and the third bellows-type expansion joint B3.

The cathode offgas line Lf is a pipe connecting the cathode of each cell stack 1 to the burner 3. More specifically, from the upstream side, the cathode offgas line Lf has eight pipes (branch pipes of the second collection manifold Md) connecting the cathode of each cell stack 1 to each inlet of the second collection manifold Md, the second collection manifold Md, and a pipe (hereinafter referred to as "pipe Lf1") connecting the outlet of the second collection manifold Md to the burner 3.

The combustion gas line Lg is a pipe connecting the burner 3 and the gas exhaust port E6. More specifically, the combustion gas line Lg has, from upstream to downstream, a heat radiation tube Za, a pipe connecting the heat radiation tube Za and the combustion gas pipe Zb, the combustion gas pipe Zb, and a pipe connecting the combustion gas pipe Zb and the gas exhaust port E6 (hereinafter referred to as "pipe Lg1"). Along the way in pipe Lg1, from upstream to downstream, a fourth bellows-type expansion joint B4, an air preheater 5, a CO oxidizer 8, and an evaporator 4 are arranged.

The burner cooling air line Lh is a pipe that connects the pipe Le1 and the startup air line Lj, and is provided with a flow rate adjustment means (such as an orifice) not shown in the figure. More specifically, the burner cooling air line Lh branches off at the midpoint of the pipe Le1 that connects the first air blower 11 and the anode off-gas cooler 6, and merges with the startup air line Lj downstream of the second air blower 14. It is configured so that a small flow rate of air Ab flows toward the burner 3 when the first air blower 11 is operating.

The cooling air line Lk is a conduit that connects the air intake E5 with a predetermined location on the conduit Lg1 (between the evaporator 4 and the gas outlet E6), and within this conduit, from upstream to downstream, are arranged a third air blower 15 and a cooling pipe Zc. The third air blower 15 is a device that pressurizes the cooling air Ad taken in through the air intake E5 and sends it downstream along the cooling air line Lk.

The reforming water line Li is a pipe connecting the condensed water recovery tank 9 and the evaporator 4, and a water pump 12 is disposed in this pipe. The water pump 12 is a device that sends the condensed water Wb stored in the condensed water recovery tank 9 to the downstream side of the reforming water line Li as reforming water Wa.

The startup air line Lj is a pipe connecting the air intake E4 and the pipe Lf1, and a second air blower 14 is disposed in this pipe. The second air blower 14 is a device that pressurizes the air Ac taken in through the air intake E4 and sends it downstream of the startup air line Lj, and is typically driven during start-up operation of the power generation unit 100.

The condensed water recovery line Lw is a conduit connecting the water-air separator Sa, located midway along the conduit Ld1, to the condensed water recovery tank 9. The water-air separator Sa separates the condensed water Wb generated in the anode off-gas condenser 7 from the anode off-gas Gd, and the separated condensed water Wb flows down the condensed water recovery line Lw. The end of the condensed water recovery line Lw is open to the gas phase without being immersed in the aqueous phase of the condensed water recovery tank 9, so that the amount of condensation does not increase or decrease due to the temperature of the stored condensed water Wb. The end of the condensed water recovery line Lw is not immersed in the aqueous phase to prevent changes in the flow rate of the anode off-gas Gd sent to the burner 3. This configuration is particularly effective when the anode off-gas Gd after separation of the condensed water Wb is recycled to the primary side of the cell stack or used for power generation in a subsequent cell stack. The water-air separation section Sa may be a T-shaped pipe with a horizontally oriented straight pipe section and a downward-facing branch pipe section. Alternatively, a small-capacity cylindrical container placed vertically may be used as the water-air separation section Sa.

Cell stack 1 is a power generation unit composed of a solid oxide fuel cell (SOFC). Solid oxide fuel cells are high-temperature operating fuel cells in which the solid electrolyte, anode, and cathode that make up the power generation cell are all made of ceramic, and a power generation unit in which a certain number of power generation cells are integrated via metal interconnect material (also known as separator material) is called a cell stack. The battery output of cell stack 1 is adjusted by power conditioner 16 before being supplied.

The reformer 2 uses steam to reform the raw fuel gas Ga, generating reformed gas Gc, which is then sent to the downstream side. The reformer 2 contains a catalyst for steam reforming, and reacts methane contained in the raw fuel gas Ga with steam to generate reformed gas Gc, which contains carbon monoxide and hydrogen. Steam reforming is an endothermic reaction, but the heat supplied by the burner 3 allows the reformer 2 to stably generate reformed gas Gc.

The burner 3 burns the incoming gas to generate heat and discharges the combustion gas Gg produced by the combustion into the combustion gas line Lg. The evaporator 4 is a device that performs indirect heat exchange between the reforming water Wa and the combustion gas Gg (heat source fluid), and serves to evaporate the reforming water Wa and heat the raw fuel gas Ga through heat exchange with the combustion gas Gg.

The air preheater 5 and the anode off-gas cooler 6 are both heat exchangers that perform indirect heat exchange between low-temperature fluid and high-temperature fluid. The air preheater 5 serves to preheat the air Aa in the cathode air line Le through heat exchange with the combustion gas Gg, and the anode off-gas cooler 6 serves to cool the anode off-gas Gd through heat exchange with the air Aa in the cathode air line Le.

The anode off-gas condenser 7 uses a fan 7a to cool the anode off-gas Gd and condense the water vapor contained in the anode off-gas Gd. In this embodiment, the anode off-gas condenser 7 is an air-cooled heat exchanger, but a water-cooled heat exchanger may be used instead, forming a cogeneration-type power generation unit in which heat recovery is performed.

The CO oxidizer 8 is a device that brings harmful carbon monoxide contained in the combustion gas Gg into contact with a catalyst and converts it into harmless carbon dioxide. The CO oxidizer 8 does not operate if the oxidation reaction in the burner 3 is complete, and only operates if the oxidation reaction in the burner 3 is incomplete.

The condensed water recovery tank 9 recovers the condensed water Wb discharged from the water-air separation section Sa and makes it reusable as reforming water Wa. The condensed water recovery tank 9 is equipped with a water level detector Sb and a drain valve Sc to adjust the level of the stored reforming water Wa within a predetermined range. When the water level detector Sb detects an upper limit water level, the drain valve Sc opens; when the water level detector Sb detects a lower limit water level, the drain valve Sc closes. In this way, the required amount of reforming water Wa is secured in the condensed water recovery tank 9. Note that to prevent anode off-gas Gd from leaking to the outside when the reforming water Wa is drained, the drain position of the drain valve Sc is set near the bottom of the condensed water recovery tank 9.

As shown by the dashed line frame in Figure 1, each cell stack 1, reformer 2, burner 3, each manifold Ma-Md, heat radiation tube Za, combustion gas pipe Zb, and cooling pipe Zc are arranged in the first region R1. The first region R1 is maintained at a temperature exceeding 600°C during power generation operation of the power generation unit 100, and independently maintains the heat balance between heat absorption and heat generation. Meanwhile, the evaporator 4, air preheater 5, anode off-gas cooler 6, and CO oxidizer 8 are arranged in the second region R2. The second region R2 is maintained at a temperature lower than that of the first region R1 but higher than room temperature during power generation operation of the power generation unit 100. The first region R1 and the second region R2 are each surrounded by an insulated box, and the two insulated boxes are integrated to form the power generation module 20. The anode off-gas condenser 7, condenser fan 7a, condensed water recovery tank 9, blowers 10, 11, 13, 14, and 15, water pump 12, power conditioner 16, and unit controller 17 are located outside the power generation module 20 (in the room temperature area). The bellows-type expansion joints B1 to B4 mentioned above are used to absorb the expansion and contraction of the piping caused by temperature changes between cold and operating conditions.

Figure 2 is a schematic diagram showing the configuration of the power conditioner 16 according to this embodiment, illustrating the internal configuration of the power conditioner 16 and its connection to peripheral devices. As mentioned above, the power generation module 20 is configured to include elements such as the cell stack 1. In addition, the auxiliary equipment 30 for operating the power generation module 20 is configured to include components such as the raw fuel blowers 10 and 13, air blowers 11, 14 and 15, a water pump 12, and the fan 7a of the anode off-gas condenser 7.

The power conditioner 16 converts the power generated by the power generation module 20 into output power equivalent to the AC power of the commercial power system 500. The power conditioner 16 includes DC/DC converters 16a and 16b, a smoothing capacitor 16c, a grid-connected inverter 16d, switches 16e and 16f, and control circuits 16g and 16h.

The DC/DC converter 16a converts the DC power from the power generation module 20 into a boost circuit. The smoothing capacitor 16c smoothes the output power of the DC/DC converter 16a. The grid-connected inverter 16d converts the output power of the DC/DC converter 16a into AC power equivalent to that of a commercial power system.

The output side of the grid-connected inverter 16d is electrically connected to a distribution panel 610 for receiving commercial power, installed within a building, for example. The grid-connected inverter 16d and the distribution panel 610 can be switched between a parallel state and a disconnected state via switch 16e. The distribution panel 610 is electrically connected to the commercial power system 500 and power demand equipment 600. The power demand equipment 600 includes multiple distribution panel boards, and each distribution panel is electrically connected to load equipment such as lighting fixtures, power units, or outlets used within the building, for example.

The grid-connected inverter 16d is also electrically connected to the independent outlet 300. The grid-connected inverter 16d and the independent outlet 300 can be switched between a connected state and a disconnected state via switch 16f. The independent outlet 300 is made up of multiple outlets into which the power plugs of various power-using devices can be inserted.

The DC/DC converter 16b and the control circuit 16g function as a drive power supply unit that supplies drive power to the auxiliary equipment 30. The DC/DC converter 16b adjusts the DC voltage boosted by the DC/DC converter 16a to a DC voltage suitable for driving the auxiliary equipment 30. The control circuit 16g supplies the DC voltage adjusted by the DC/DC converter 16b to the auxiliary equipment 30, thereby driving the auxiliary equipment 30 appropriately. The above-mentioned auxiliary equipment 30 is driven using commercial power during startup and shutdown operations of the power generation unit 100, and is driven using generated power during power generation operation of the power generation unit 100.

The DC/DC converter 16a and control circuit 16h function as an operating power supply unit that supplies operating power to the first load module 40 and the second load module 50. The first load module 40 is configured to include an electric heater 41 and a heat dissipation fan 42. Similarly, the second load module 50 is configured to include an electric heater 51 and a heat dissipation fan 52. In each load module 40, 50, when the power generation unit 100 is in standalone operation mode, the electric heaters 41, 52 generate heat, consuming excess power generated by the cell stack 1, and the heat dissipation fans 42, 52 send airflow to the electric heaters 41, 51, respectively, to promote heat dissipation.

In addition to the load modules 40 and 50, an auxiliary resistor (not shown) is connected to the control circuit 16h. This auxiliary resistor is provided to consume excess power generated by the cell stack 1 when the power generation unit 100 is in standalone operation mode, and functions as a buffer when the operating power of the auxiliary equipment 30 fluctuates, for example.

The unit controller 17 controls the operation of the power generation unit 100 in accordance with a control program that has been created and stored in advance. The unit controller 17 is composed of a programmable logic controller (PLC). The PLC has a calculation unit, a memory device, an input device, an output device, and a power supply unit, and performs the required calculations and sequence control using a processing program that has been created and stored in advance. The unit controller 17 is provided with a communication unit 17a that communicates with the outside of the power generation unit 100.

<Outline of power generation unit operation>
Next, an overview of the operation of the power generation unit 100 will be described with reference to Fig. 1. The raw fuel gas Ga supplied from the fuel inlet E2 into the mixed gas line Lb is sent to the downstream side by the action of the first raw fuel blower 10. In parallel with the supply of the raw fuel gas Ga, the reforming water Wa supplied from the condensed water recovery tank 9 into the reforming water line Li has its amount adjusted by the water pump 12 and flows into the mixed gas line Lb.

The reforming water Wa flows into the evaporator 4 together with the raw fuel gas Ga in the mixed gas line Lb, where it is heated by heat exchange to become water vapor (superheated steam). This water vapor mixes with the heated raw fuel gas Ga and flows into the reformer 2 as mixed gas Gb.

The reformer 2 uses the water vapor in the mixed gas Gb to reform the raw fuel gas Ga, generating reformed gas Gc, which is then sent to the downstream side. The reformed gas Gc sent from the reformer 2 passes through the anode fuel line Lc and is distributed to the anodes of each cell stack 1.

Meanwhile, in parallel with the supply of the raw fuel gas Ga described above, air Aa is supplied from the air intake E3 into the cathode air line Le. The air Aa in the cathode air line Le is sent to the downstream side by the action of the first air blower 11. This air Aa is heated by heat exchange in the anode off-gas cooler 6, and then further heated by heat exchange in the air preheater 5 before being distributed to the cathodes of each cell stack 1. Note that, in order to adjust the temperature of the air Aa, it is also possible to flow a portion of the air Aa, air Aa1, into the cathodes of each cell stack 1 via bypass path Le2.

Furthermore, air Ab is supplied into the burner cooling air line Lh in synchronization with the supply of air Aa to the cathode. The air Ab in the burner cooling air line Lh is sent to the burner 3 by the action of the first air blower 11. This air Ab acts as a coolant to lower the combustion temperature of the burner 3.

Each cell stack 1 generates electricity using reformed gas Gc that flows into the anode and air Aa that flows into the cathode. When reformed gas Gc and air Aa are supplied to the cell stack 1 and a current sweep is performed by the power conditioner 16, electricity generation in the cell stack 1 (electrochemical reaction between the reformed gas and oxygen) begins. During power generation operation in the cell stack 1, anode offgas Gd is discharged from the anode to the anode offgas line Ld, and cathode offgas Ge is discharged from the cathode to the cathode offgas line Lf. The anode offgas Gd contains reformed gas that did not react at the anode, and the cathode offgas Ge contains oxygen that did not react at the cathode.

The anode off-gas Gd discharged from each cell stack 1 to the anode off-gas line Ld is collected in the first collection manifold Mc, cooled by heat exchange in the anode off-gas cooler 6, and flows into the anode off-gas condenser 7. In the anode off-gas condenser 7, the anode off-gas Gd is cooled to below the dew point temperature, and the water vapor contained in the anode off-gas Gd condenses.

The anode off-gas Gd that passes through the anode off-gas condenser 7 is sent to the steam-water separation section Sa where it is separated into steam and water, and the condensed water Wb is collected in the condensed water recovery tank 9. As mentioned above, the condensed water Wb collected in the condensed water recovery tank 9 is reused as reforming water Wa. The process of collecting water produced by the electrochemical reaction between the reformed gas Gc and oxygen and repeatedly using it in the steam reforming reaction is called water self-sustaining. The uncondensed portion of the anode off-gas Gd (anode off-gas Gd after steam-water separation) is sent to the burner 3.

The cathode offgas Ge discharged from each cell stack 1 to the cathode offgas line Lf is collected in the second collection manifold Md, then mixed in pipe Lf1 with air Ab flowing in via the burner cooling air line Lh, and sent to the burner 3. Depending on the operating state of the power generation unit 100, raw fuel gas Gf supplied from the fuel inlet E1 is sent to the burner 3 via the raw fuel line La, and air Ac supplied from the air inlet E4 is sent to the burner 3 via the startup air line Lj.

The burner 3 receives the first burner gas Gx, which is raw fuel gas Gf and/or anode offgas Gd, and the second burner gas Gy, which is air Ac and/or cathode offgas Ge, and combusts them to generate heat. Specifically, the first burner gas Gx is either a mixture of raw fuel gas Gf and anode offgas Gd, or either raw fuel gas Gf or anode offgas Gd, and the state of the first burner gas Gx can vary depending on the operating state of the power generation unit 100, among other factors. The second burner gas Gy is either a mixture of air Ac and cathode offgas Ge, or either air Ac or cathode offgas Ge, and the state of the second burner gas Gy can vary depending on the operating state of the power generation unit, among other factors. In other words, the state of the gas supplied to the burner 3 changes appropriately depending on the power generation unit 100's startup operation, power generation operation (full load operation or partial load operation), shutdown operation, etc.

The raw fuel gas Gf is a type of hydrocarbon-containing gas. On the other hand, air Ac is a type of oxidant-containing gas. During combustion operation of the burner 3, air Ab is continuously supplied from the burner cooling air line Lh to adjust the combustion temperature.

The combustion gas Gg generated by combustion in the burner 3 is sent to the combustion gas line Lg, passes through the heat radiation tube Za, combustion gas pipe Zb, air preheater 5, CO oxidizer 8, and evaporator 4 in that order, and is discharged to the outside of the power generation module 20 through the gas outlet E6. The heat radiation tube Za and combustion gas pipe Zb are positioned so that the combustion gas Gg can be used to effectively heat the reformer 2. Furthermore, the combustion gas Gg in the combustion gas line Lg is used for heat exchange as it passes through the air preheater 5 and evaporator 4, and if it contains carbon monoxide, the carbon monoxide is converted to carbon dioxide as it passes through the CO oxidizer 8.

In addition, the cooling air Ad supplied from the air intake E5 to the cooling air line Lk serves to cool the inside of the power generation module 20 as it passes through the cooling pipe Zc. As described below, the cooling pipe Zc is installed near the cell stack 1, allowing the cooling air Ad to effectively cool the cell stack 1. The cooling air Ad then passes through the collection pipe Lk1 and is ultimately discharged to the outside of the power generation module 20 from the gas outlet E6 together with the combustion gas Gg.

In addition, the power generation unit 100 controls the heat quantity (temperature) inside the power generation module 20 by adjusting the flow rate of cooling air Ad introduced into the cooling pipe Zc. As an example, when the discharge temperature of the cathode off-gas Ge flowing out from the cell stack 1 exceeds an upper limit temperature, the unit controller 17 drives the third air blower 15 and controls the rotation speed of the third air blower 15 so that the discharge temperature of the cathode off-gas Ge becomes a target temperature (a temperature that is a predetermined temperature lower than the upper limit temperature). As the rotation speed of the third air blower 15 increases, the flow rate of the cooling air Ad introduced into the cooling pipe Zc increases. Furthermore, the unit controller 17 stops the third air blower 15 when the rotation speed remains below the lower limit for a predetermined period of time.

The cooling pipe Zc installed near the cell stack 1 can also be used to heat the cell stack 1 during startup operation of the power generation unit 100. Specifically, during startup operation of the power generation unit 100, the second raw fuel blower 13 and the second air blower 14 are first driven to combust the burner 3. The combustion gas Gg generated by this combustion flows through the heat radiation tube Za and the combustion gas pipe Zb, heating the cold reformer 2 from the outside by radiant heat transfer and raising its temperature. Furthermore, the combustion gas Gg serves as a heat source for the evaporator 4, generating steam from the reforming water Wa. This steam flows sequentially through the cold reformer 2 and the cell stack 1, heating these devices from the inside by thermal conduction and raising their temperatures. If there is residual heat in the combustion gas Gg discharged from the evaporator 4, the combustion gas Gg is allowed to flow from the pipe Lg1 into the collection pipe Lk1. This allows combustion gas Gg to flow through the cooling pipe Zc, allowing the cold cell stack 1 to be heated from the outside by radiant heat transfer and increase in temperature.

During the power generation operation of the power generation unit 100, balancing the heat balance between the heat generated by the electrochemical reaction between reformed gas Gc and oxygen in the cell stack 1, the heat generated by the combustion reaction between anode off-gas Gd and cathode off-gas Ge in the burner 3, and the heat absorbed by the steam reforming reaction between raw fuel gas Ga and steam (reforming water Wa) in the reformer 2 is called "thermal self-sustaining." Furthermore, recovering the water (reforming water Wa) produced by the electrochemical reaction between reformed gas Gc and oxygen and repeatedly using it for the steam reforming reaction is called "water self-sustaining."

When the power generating unit 100 is operating in power generation mode, the output power of the grid-connected inverter 16d is equal to the value obtained by subtracting the sum of the power loss due to operation of the auxiliary equipment 30, the power loss due to operation of the power conditioner 16, and the power loss due to operation of the load module 40. The load module 40 is operated in the stand-alone power operation mode described below.

When the power generation unit 100 is operated at full load with rated output power, the unit controller 17 sets the sweep current value for the cell stack 1 to the rated current value and supplies an amount of raw fuel gas Ga corresponding to this. When the power generation unit 100 is operated at partial load with less than the rated output power but equal to or greater than the minimum output power, the unit controller 17 sets the sweep current value for the cell stack 1 to a range less than the rated current value but equal to or greater than the lower limit current value and supplies an amount of raw fuel gas Ga corresponding to this. When the power generation unit 100 is put into standby with zero output power, the unit controller 17 sets the sweep current value for the cell stack 1 to be equivalent to the operating power of the auxiliary equipment 30 and supplies a minimum amount of raw fuel gas Ga while keeping the power generation module 20 warm. The state in which the power generation unit 100 is put into standby with zero output power is referred to as "hot standby."

The power generation operation of the power generation unit 100 includes a grid-connected operation mode and an independent operation mode. In the grid-connected operation mode, as shown in Figure 2, switch 16e is controlled to the on state and switch 16f is controlled to the off state. This causes the power generation unit 100 to operate in parallel with the commercial power system 500. In the independent operation mode, in contrast to Figure 2, switch 16e is controlled to the off state and switch 16f is controlled to the on state. This causes the power generation unit 100 to operate in a state of disconnection from the commercial power system 500.

The unit controller 17 constantly monitors the commercial power system 500 for power outages, and when a power outage is detected, it transitions the power generation unit 100 from grid-connected operation mode to independent operation mode. In independent operation mode, when a power-using device is connected to the independent outlet 300, the output power of the grid-connected inverter 16d can be supplied to the power-using device as independent operation power. In other words, when in a disconnected state, a portion of the power generated by the power generation module 20 is supplied to the power-using device via the independent outlet 300. When the commercial power system 500 recovers from a power outage, the unit controller 17 transitions the power generation unit 100 from independent operation mode to grid-connected operation mode.

When the supply of independent operation power exceeds the consumption in independent operation mode, the power generation unit 100 consumes the surplus independent operation power (i.e., a portion of the power generated by the power generation module 20) using the first load module 40 and the second load module 50. The power consumption of the load module 40 can be adjusted by adjusting the heat output of the electric heater 41 (for example, by adjusting the number of electric heaters that are energized or the on/off duty ratio of the power), and the same applies to the second load module 50.

<Operation as an output regulator>
As described above, the power generating unit 100 can be operated at full load at the rated output power, at partial load below the rated output power but above the minimum output power, or in hot standby mode with zero output power. That is, the power generating unit 100 can be operated as an output regulator that operates in a range below the rated output power but above the minimum output power. Note that, since the power generating module 20 in this embodiment includes an SOFC cell stack, the minimum output power during partial load operation is set based on the minimum fuel supply amount that allows the power generating module 20 to maintain thermal independence and the minimum fuel utilization rate that allows the power generating module 20 to maintain water independence.

The maximum output power of the power generation unit 100 in grid-connected operation mode is equivalent to the rated output power (6 kW). Furthermore, the minimum output power of the power generation unit 100 in grid-connected operation mode is set to the lower limit at which, in addition to achieving both thermal and water independence, power generation efficiency during partial load operation does not decrease compared to power generation efficiency during full load operation. In this case, the minimum output power is, for example, equivalent to 50% (3 kW) of the rated output power (6 kW). Furthermore, if output adjustment below the minimum output power is required, the unit will transition to hot standby.

The maximum output power of the power generating unit 100 in the isolated operation mode is determined taking into account the deterioration of the cell stack 1 over time. In this case, the maximum output power is, for example, equivalent to 83% (5 kW) of the rated output power (6 kW). The minimum output power of the power generating unit 100 in the isolated operation mode is set to a lower limit that allows for both thermal and water independence, as well as a decrease in power generation efficiency during partial load operation compared to full load operation. In this case, the minimum output power is, for example, equivalent to 25% (1.5 kW) of the rated output power (6 kW). If the power generation capacity of the cell stack 1 decreases due to deterioration over time, the rated output power cannot be secured in the grid-connected operation mode. However, this does not interfere with system operation because the decrease in output power can be compensated for by increasing purchased power.

The output adjuster adjusts the output power from the power conditioner 16 by increasing or decreasing the output current from the grid-connected inverter 16d. The unit controller 17 increases the sweep current value for the cell stack 1 in parallel with an increase in the output current, and increases the supply amount of raw fuel gas Ga. Furthermore, the unit controller 17 decreases the sweep current value for the cell stack 1 in parallel with a decrease in the output current, and decreases the supply amount of raw fuel gas Ga. This increases or decreases the power generated by the power generation module 20 in accordance with an increase or decrease in the output current.

<Load module configuration>
Fig. 3 is a perspective view showing the appearance of the power generation unit 100. As shown in Fig. 3, the power generation unit 100 includes, as a product configuration, a unit base 60 on which the above-described power generation modules 20 and auxiliary machinery 30 are placed, and a box-shaped housing 62 installed on the unit base 60 so as to enclose the power generation modules 20 and auxiliary machinery 30.

Inside the front side of the housing 62, a power conditioner 16 is arranged on the lower level, and a unit controller 17 is arranged on the upper level. Inside the rear side of the housing 62, a first load module 40 is arranged, and a second load module 50 is placed on the top panel (top plate) of the housing 62. In addition, a socket unit 400 equipped with a plurality of free-standing sockets 300 (described below) is provided on the front panel of the housing 62.

After switching to standalone operation mode, the power generation unit 100 can adjust its output within a range from minimum output power (25% output) to maximum output power (83% output), and the outlet unit 400 can extract the maximum value of standalone generated power selected from this range.

The first load module 40 is standard equipment on the power generation unit 100. The first load module 40 is equipped with an electric heater 41 that consumes at least the amount of power equivalent to the minimum output power (25% output) of the power generation unit 100 in standalone operation mode.

The second load module 50 can be optionally installed depending on the customer's power needs. The second load module 50 is equipped with an electric heater 51 that consumes at least the amount of power equivalent to the maximum output power minus the minimum output power of the power generation unit 100 in standalone operation mode (58% output).

In a specific design example, if the rated output power of the power generation unit 100 is 6 kW, the number of heaters and other factors of the electric heaters 41 in the first load module 40 are designed so that the maximum power consumption is 1.5 kW or more, and the power consumption is adjustable in the range of 0 to 1.5 kW. The number of heaters and other factors of the electric heaters 51 in the second load module 50 are designed so that the maximum power consumption is 3.5 kW or more, and the power consumption is adjustable in the range of 0 to 3.5 kW. In other words, when two load modules 40, 50 are used, the design allows the power consumption to be adjusted in the range of 0 to 5 kW.

<Configuration of independent outlet>
Figure 4 is an enlarged view of outlet unit 400. As shown in Figure 4, outlet unit 400 includes a panel 401, a power lamp 402, an information display unit 403, and three self-contained outlets 300a to 300c. The surface of panel 401 exposed to the front is formed flat, and this surface is arranged parallel to the outer surface of the front panel of housing 62. On the surface of panel 401, the three self-contained outlets 300 are arranged near the right side, and the power lamp 402 and information display unit 403 are arranged near the left side thereof.

The self-contained outlet 300 has a socket exposed at the front, allowing power plugs for various types of power-using devices to be inserted from the front. By inserting a power plug into this socket, the power-using device is connected to the self-contained outlet 300. In the example shown in Figure 4, three self-contained outlets 300a, 300b, and 300c are provided, but the number of self-contained outlets 300 is not limited to this.

The power lamp 402 lights up when a power-using device is connected to the standalone outlet 300 and standalone power can be supplied (when switch 16f is on), and it is visible from the front whether the lamp is on or off. This allows the consumer to instantly determine whether the standalone outlet 300 is currently available for use.

The information display unit 403 displays information corresponding to the power consumption of the standalone operation power of the power-using equipment connected to the standalone outlet 300. The information display unit 403 in the example shown in Figure 5 is configured as a 7-segment display capable of displaying multi-digit numbers, and the displayed numbers are visible from the front. Because the display of the information display unit 403 is positioned close to the outlet of the standalone outlet 300, consumers in front of the outlet (especially consumers who intend to use the standalone outlet 300) can easily see the display.

The power that can be supplied by the independent outlet 300 can be set within a range greater than or equal to the minimum output power and less than or equal to the maximum output power in independent operation mode, based on the equipment information of the first load module 40 and the second load module 50.

As described above, the first load module 40 is equipped with an electric heater 41 with a power consumption (1.5 kW) equivalent to the minimum output power (25% output) in standalone operation mode. If the second load module 50 is not installed, the first load module 40 can consume all of the minimum output power when no power-using equipment is connected to the standalone outlet 300. In other words, when the first load module 40 is not operating, all of the minimum output power (1.5 kW) can be extracted from the standalone outlet 300. In other words, when only the first load module 40 is installed as standard, the power that can be supplied by the standalone outlet 300 can be set to the minimum output power (1.5 kW).

The second load module 50 is also equipped with an electric heater 51 with a power consumption (3.5 kW) equivalent to 58% of the maximum output power in standalone operation mode. When the second load module 50 is installed, the first load module 40 and the second load module 50 can consume all of the maximum output power when no power-using equipment is connected to the standalone outlet 300. In other words, when the two load modules 40, 50 are not operating, all of the maximum output power (5 kW) can be extracted from the standalone outlet 300. In other words, when the second load module 50 is additionally installed, the power that can be supplied by the standalone outlet 300 can be set to the maximum output power (5 kW).

<Output adjustment of independent outlet>
While the power generating unit 100 is operating in the independent operation mode, the unit controller 17 adjusts the power consumption of the load modules 40, 50 so that the effective output power Qe of the independent outlet 300, calculated by subtracting the first power loss Q1 due to the operation of the load modules 40, 50 from the generated power Qg of the power generating module 20, follows the power consumption Qc of the power consuming equipment. This relationship is expressed by Equation (1). Since the power consumption Qc of the power consuming equipment is a variable value, this relationship means that if the generated power Qg of the power generating module 20 is a constant value, the first power loss Q1 of the load modules 40, 50, i.e., the power consumption of the electric heaters 41, 51, is increased or decreased.
Qc=Qe=Qg-Q1...(1)

As described above, the power consumption of the load modules 40, 50 is adjusted by increasing or decreasing the number of electric heaters 41, 51 that are energized, or by adjusting the on/off duty ratio of the electric heaters 41, 51.

Furthermore, while the power generating unit 100 is operating in the isolated operation mode, the unit controller 17 operates the power generating module 40 so as to obtain the generated power Qg, which is the sum of the set value Qs of the available power supply from the isolated outlet 300, the second power loss Q2 due to operation of the auxiliary device 30, and the third power loss Q3 due to operation of the power conditioner 16. This relationship is expressed by equation (2). This relationship means that, assuming that the second power loss Q2 and the third power loss Q3 are approximately constant values, the generated power Qg of the power generating module 20 will be determined as a constant value when the set value Qs of the available power supply is given.
Qg=Qs+Q2+Q3...(2)

The second power loss Q2 includes the power consumption of the raw fuel blowers 10, 13, air blowers 11, 14, 15, water pump 12, and condenser fan 7a, as well as the power consumption of the heat dissipation fans 42, 52 and auxiliary resistor. In other words, the first power loss Q1 includes only the power consumption of the electric heaters 41, 51. In addition, in the standalone operation mode, the second power loss Q2 is maintained at a roughly constant value by the operation of the auxiliary resistor.

Since the available power supply Qs is equal to the maximum power consumption of the load modules 40 and 50 (the maximum value of the first power loss Q1), the following formula (3) can be obtained from formulas (1) and (2). In other words, if the generated power Qg, the second power loss Q2, and the third power loss Q3 are assumed to be approximately constant, the effective output power Qe of the autonomous outlet 300 can be made to match the power consumption Qc of the power-using device by increasing or decreasing the first power loss Q1 due to the operation of the electric heaters 41 and 51.
Qc=Qe=Qg-Q1-Q2-Q3...(3)

Second Embodiment
Fig. 6 is a schematic diagram showing the configuration of a power generation unit according to the second embodiment. As shown in Fig. 5, the power generation unit 100 is a cogeneration type that uses a fuel cell, and is provided with a heat recovery unit 200, which will be described later.

In this embodiment, the auxiliary equipment 30 for operating the power generation module 20 includes the raw fuel blowers 10, 13, air blowers 11, 14, 15, and water pump 12, as well as the fan 63a of the radiator 63 and the circulation pump 64, which will be described later. The anode off-gas condenser 7 has been changed to a water-cooled type, so the fan 7a mentioned above is not included.

<Configuration of heat recovery unit>
Fig. 6 is a schematic diagram showing the configuration of the heat recovery unit according to this embodiment. As shown in Fig. 6, some of the devices in the power generation unit 100, together with the hot water storage tank 65, form a heat recovery unit 200. The heat recovery unit 200 recovers heat from at least one of the anode off-gas Gd and the combustion gas Gg, and makes the recovered heat available for heating the hot water stored in the hot water storage tank 65.

The heat recovery unit 200 is primarily composed of an anode off-gas condenser 7, a heat recovery unit 61, a heater 62, a radiator 63, a circulation pump 64, a hot water storage tank 65, and a cooling water line Lm. The cooling water line Lm circulates the cooling water Wc so that it passes through the heat recovery unit 61, the anode off-gas condenser 7, the heater 62, the circulation pump 64, and the radiator 63 in that order before returning to the heat recovery unit 61. The hot water storage tank 65 in this embodiment is a sealed hot water storage tank, such as those used in heat pump water heaters.

The heater 62 is a heat exchange coil placed in the hot water storage tank 65, and heats the hot water in the hot water storage tank 65 using the heat of the cooling water Wc. The circulation pump 64 is a device that circulates the cooling water Wc in the cooling water line Lm, and has an adjustable rotation speed. By changing the rotation speed of the circulation pump 64, it is possible to adjust the circulating flow rate of the cooling water Wc. The radiator 63 is configured to efficiently radiate the heat of the cooling water Wc using a fan 63a.

The operation of the heat recovery unit 200 is controlled by the unit controller 17. Specifically, the rotation speed of the circulation pump 64 is controlled so that the return temperature of the cooling water We (the temperature near the outlet of the anode off-gas condenser 7) becomes a predetermined target temperature Ts. Note that if the return temperature exceeds the target temperature Ts even when the rotation speed of the circulation pump 64 is adjusted to its upper limit, the fan 63a of the radiator 63 is driven to promote heat dissipation from the cooling water We in order to ensure the cooling amount of the anode off-gas Gd in the anode off-gas condenser 7. The fan 63a of the radiator 63 is driven when there is no hot water consumption at the demand destination and the heat storage amount (heat recovery amount) of the hot water storage tank 65 is at its maximum.

In this embodiment, as an example, the target temperature Ts is set so that the hot water in the hot water storage tank 65 is approximately 75°C. However, the actual temperature of the hot water in the hot water storage tank 65 may fluctuate depending on factors such as the demand for hot water at that time. For example, immediately after water supply Wd is supplied to a hot water storage tank 65 that has run out of hot water, the temperature of the hot water in the hot water storage tank 65 may fall significantly below 75°C. Also, if the condensed water Wb in the condensed water recovery tank 9 falls below the lower limit level when the rotation speed of the circulation pump 64 is below its upper limit, the fan 63a of the radiator 63 is driven to restore the stored water volume.

The specific configuration of the heat recovery unit 200 is not limited to that shown in FIG. 6 and can be modified according to various circumstances. For example, in the example of FIG. 6, the anode off-gas condenser 7 is located downstream of the heat recovery device 61, but the heat recovery device 61 may also be located downstream of the anode off-gas condenser 7. Furthermore, if the temperature of the combustion gas Gg after thermal utilization in the evaporator 4 or the like is low, the heat recovery device 61 may be omitted. Furthermore, the heater 62 may be omitted, and instead of the cooling water line Lm, a path for circulating hot water in the hot water storage tank 65 (a path for circulating hot water that passes through the hot water storage tank 65, circulation pump 64, radiator 63, heat recovery device 61, and anode off-gas condenser 7 in this order and returns to the hot water storage tank 65) may be provided. In this case, it is preferable that the hot water returning to the hot water storage tank 65 be returned to the top of the hot water storage tank 65.

In addition to the hot water storage tank 65, the heat recovery unit 200 is equipped with a water heater 66, a temperature control valve 67, and a water supply line Ln, and serves to supply hot water to the demand destination at the required temperature (the hot water temperature or temperature range required by the demand destination). In this embodiment, as an example, this required temperature is in the range of 50 to 60°C.

The water heater 66 is located downstream of the hot water storage tank 65 and sends hot water supplied from the hot water storage tank 55 to the consumer, and is capable of heating the water. In this embodiment, a gas water heater that heats the water by burning city gas, propane gas, or the like is used as the water heater 66.

The temperature control valve 67 is located downstream of the water heater 66 and is capable of mixing water supply Wd with the hot water delivered from the water heater 66 to lower the temperature. The water supply line Ln is a line that supplies water supply Wd to the hot water storage tank 65 and the temperature control valve 67. The hot water storage tank 65 is supplied with water supply Wd in an amount corresponding to the hot water consumed at the demand destination, and the temperature control valve 67 is supplied with water supply Wd in an amount used in the mixing operation. The water supply Wd can be tap water, well water, or softened water treated with a water softener.

<Output adjustment of independent outlet>
In the above equations (1) to (3), the second power loss Q2 is assumed to be a generally constant value due to the operation of the auxiliary resistor. However, without the auxiliary resistor, the second power loss Q2 may fluctuate significantly depending on the rotation speed of the radiator fan 63a and the circulation pump 64. In such cases, it is desirable to adjust the generated power Qg of the power generating module 20 taking into account the actual value of the second power loss Q2. Adjusting the generated power Qg in accordance with the second power loss Q2 ensures that the effective output power Qe matches the consumed power Qc, thereby stabilizing the output voltage of the autonomous outlet 300.

For example, if the raw fuel blowers 10, 13, air blowers 11, 14, 15, water pump 12, condenser fan 7a, radiator fans 42, 52, radiator fan 63a, and circulation pump 64 are driven by DC motors, these fluid machines control their rotation speed and increase or decrease their flow rate by changing the drive voltage (average voltage) using pulse width modulation (PWM). Therefore, a table of DC motor duty ratios and shaft power (power consumption) is created in advance, and the power consumption of each fluid machine is calculated from the current duty ratio. Then, by adding up the numerical values of each power consumption, it becomes possible to accurately determine the second power loss Q2.

[Other variations]

Instead of dissipating excess power in the electric heater 41, each of the first load module 40 and the second load module 50 may be configured to dissipate it in an electrical resistance circuit or a switching element.

The cell stack 1 that constitutes the power generation module 20 may be a molten carbon dioxide fuel cell (MCFC) instead of a solid oxide fuel cell (SOFC). Like SOFCs, MCFCs are high-temperature operating fuel cells and have high power generation efficiency.

The power generation module 20 using fuel cells is not limited to a type that generates power using a single cell stack 1, but may also be a type that generates power using two or more cell stacks 1. Specifically, water vapor is removed from the anode off-gas discharged from the previous cell stack to generate regenerated gas, which is then supplied to the anode of the next cell stack. When generating the regenerated gas, carbon dioxide contained in the anode off-gas may be removed using a separation membrane or absorbent. By configuring the module to generate power using two or more cell stacks, the fuel utilization rate can be significantly increased.

The fuel cell-based power generation module 20 is not limited to a configuration that supplies reformed gas to the cell stack; it may also be configured to supply pure hydrogen gas. Specifically, hydrogen gas supplied from an external hydrogen production site via transportation infrastructure is introduced into the anode of the cell stack. When hydrogen gas is used as the raw fuel, the components required for steam reforming and water self-sustaining (reformer 2, evaporator 4, anode off-gas condenser 7, steam-water separator Sa, condensed water recovery tank 9, water pump 12, etc.) can be omitted.

The power generation unit 100 is not limited to a type that uses a fuel cell, and can be modified to other types. The power generation unit may be a type that uses a solar cell, or a type that uses an organic Rankine cycle, a steam turbine, a gas turbine, or a gas engine to rotate a generator.

The power generation unit assembly 2000 of this embodiment described above provides the following advantages:

(1) The power generation unit 100, which is operated in a parallel or disconnected state with respect to the commercial power system 500, comprises a power generation module 20 operated by an auxiliary device 30, a power conditioner 16 that converts the power generated by the power generation module 20 into output power equivalent to the AC power of the commercial power system 500, a unit controller 17 that controls the power generation module 20 and the auxiliary device 30, an independent outlet 300 that supplies a portion of the power generated by the power generation module 20 to power-using equipment when in a disconnected state, and an internal power supply 300 that supplies a portion of the power generated by the power generation module 20 to power-using equipment when in a disconnected state. The power generation module 20 is also provided with load modules 40, 50 that consume power in the grid-connected operation mode, and the unit controller 17 and power conditioner 16 are configured to operate in grid-connected operation mode in a parallel state and in isolated operation mode in a disconnected state. During operation in isolated operation mode, the unit controller 17 adjusts the power consumption of the load modules 40, 50 so that the effective output power Qe, calculated by subtracting the first power loss Q1 due to the operation of the load modules 40, 50 from the power generation power Qg of the power generation module 20, follows the power consumption Qc of the power-using equipment.

The effective output power Qe (= Qg - Q1) is the actual power supplied from the independent outlet 300 to the power-using equipment. The effective output power Qe can be adjusted by increasing or decreasing the power consumption of the electric heaters 41, 51 to change the first power loss Q1 of the load modules 40, 50 when the power generation power Qg of the power generation module 20 is constant. Therefore, adjusting the effective output power Qe to follow the power consumption Qc of the power-using equipment stabilizes the output voltage of the independent outlet 300. This allows the power-using equipment to operate properly, making it possible to meet the power needs of consumers during a power outage.

(2) In the power generation unit 100 of (1), the load modules 40, 50 consume at least the amount of power that can be supplied Qs when no power-using device is connected to the self-contained outlet 300.

When the load modules 40, 50 are not operating, all of the available power supply Qs can be extracted from the independent outlet 300. On the other hand, when the load modules 40, 50 are operating at maximum power consumption, the output from the independent outlet 300 is zero. The load module 40 consumes excess output power in accordance with fluctuations in the power consumption Qc of the power-using devices connected to the independent outlet 300, so the output voltage of the independent outlet 300 can be stabilized regardless of the power consumption Qc.

(3) In the power generation unit 100 of (2), when operating in the independent operation mode, the unit controller 17 operates the power generation module 20 so as to obtain the generated power Qg, which is the sum of the available power Qs, the second power loss Q2 due to the operation of the auxiliary equipment 30, and the third power loss Q3 due to the operation of the power conditioner 16.

If the power generation output Qg of the power generation module 20 is set as the available power supply Qs, the power sent from the grid-connected inverter 16d to the independent outlet 300 will decrease due to the operation of the auxiliary equipment 30 and the power conditioner 16. Therefore, if an electric power-using device with a power consumption Qc equal to the available power supply Qs is connected to the independent outlet 300, the electric power-using device will not operate normally. On the other hand, if the power generation output Qg of the power generation module 20 is adjusted taking into account the second power loss Q2 and the third power loss Q3, the maximum power sent from the grid-connected inverter 16d to the independent outlet 300 will be equal to the available power supply Qs. As a result, even if an electric power-using device with a large power consumption Qc is connected to the independent outlet 300, it will operate normally.

(4) In the power generation unit 100 of (3), the power generation module 20 includes a cell stack 1 that integrates solid oxide fuel cells, and the auxiliary equipment 30 includes fluid transfer equipment (raw fuel blower 10, first air blower 11, water pump 12, third air blower 15, fan 53a, circulation pump 54, etc.) for transferring fluids necessary for the power generation operation of the cell stack 1, and the second power loss Q2 is a power loss corresponding to changes in the operating state of the fluid transfer equipment.

In the power generation unit 100 using SOFC, the second power loss Q2 due to the operation of the auxiliary equipment 30 can fluctuate significantly depending on the control state, such as in the case of cogeneration specifications. Therefore, the power generation power Qg of the power generation module 20 is adjusted taking into account the actual value of the second power loss Q2 in response to changes in the operating state of the auxiliary equipment 30 for fluid transfer. This ensures that the effective output power Qe matches the power consumption Qc, stabilizing the output voltage of the autonomous outlet 300.

(5) In the power generation units 100 of (1) to (4), the first load module 40a and the second load module 40b each include one selected from an electric heater 41, an electric resistance circuit, and a switching element.

Load devices such as electric heaters 41 convert electrical energy into thermal energy and consume excess power. The amount of heat generated by these load devices can be easily controlled using a relatively simple control circuit, making them suitable for use as load modules 40 that are used exclusively during power outages in the commercial power system 500.

Although the above describes an embodiment of the present invention, the configuration of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. In other words, the above embodiment is illustrative in all respects and should be considered not to be limiting. The technical scope of the present invention is defined by the claims, not the description of the above embodiment, and should be understood to include all modifications that fall within the meaning and scope of the claims.

[Contributing to the United Nations-led Sustainable Development Goals (SDGs)]
The power generation unit and power supply system according to the present disclosure reduce carbon dioxide emissions by improving primary energy efficiency, and can contribute to the realization of SDG Goal 13, "Take urgent action to combat climate change." Furthermore, the power generation unit and power supply system according to the present disclosure can independently maintain power supply in the event of a power outage caused by a natural disaster, and can contribute to the realization of SDG Goal 11, "Make cities and towns inclusive and sustainable."

REFERENCE SIGNS LIST 1 Cell stack 2 Reformer 3 Burner 4 Evaporator 5 Air preheater 6 Anode off-gas cooler 7 Anode off-gas condenser 7a Fan 8 CO oxidizer (carbon monoxide oxidizer)
DESCRIPTION OF SYMBOLS 9 Condensed water recovery tank 10 First raw fuel blower 11 First air blower 12 Water pump 13 Second raw fuel blower 14 Second air blower 15 Third air blower 16 Power conditioner 16a, 16b DC/DC converter 16c Smoothing capacitor 16d Grid-connected inverter 16e, 16f Switch 16g, 16h Control circuit 17 Unit controller 17a Communication unit 20 Power generation module 30 Auxiliary equipment 40 First load module 41 Electric heater 42 Heat dissipation fan 50 Second load module 51 Electric heater 52 Heat dissipation fan 61 Heat recovery unit 62 Heater 63 Heat dissipator 63a Fan 64 Circulation pump 65 Heat medium tank (hot water storage tank)
66 Combustion-type water heater (gas water heater)
67 Temperature control valve 100 Power generation unit 200 Heat recovery unit 300 Self-contained outlet 300a, 300b, 300c Self-contained outlet 400 Outlet unit 401 Panel 402 Power lamp 403 Information display unit 500 Commercial power supply system 600 Demand equipment 610 Distribution board Aa, Ab, Ac Air Ad Cooling air B1 First bellows type expansion joint B2 Second bellows type expansion joint B3 Third bellows type expansion joint B4 Fourth bellows type expansion joint E1, E2 Fuel inlet E3, E4, E5 Air inlet E6 Gas outlet Ga, Gf Raw fuel gas Gb Mixed gas Gc Reformed gas Gd Anode off-gas Ge Cathode off-gas Gg Combustion gas La Raw fuel line Lb Mixed gas line Lc Anode fuel line Ld Anode off-gas line Le Cathode air line Lf Cathode off-gas line Lg Combustion gas line Lh Burner cooling air line Li Reforming water line Lj Start-up air line Lk Cooling air line Lk1 Collection pipe Lm Cooling water line Ln Water supply line Lw Condensed water recovery line Ma First distribution manifold Mb Second distribution manifold Mc First collection manifold Md Second collection manifold R1 First region R2 Second region Sa Air-water separator Sb Water level detector Sc Drain valve Wa Reforming water Wb Condensed water Za Heat radiation tube Zb Combustion gas pipe Zc Cooling pipe

Claims (5)

A power generation unit that is operated in a parallel state or in a disconnected state with respect to a commercial power system,
a power generation module operated by the auxiliary equipment;
a power conditioner that converts the power generated by the power generation module into output power equivalent to AC power of the commercial power supply system;
a controller for controlling the power generation module and the auxiliary equipment;
an independent outlet that supplies a portion of the power generated by the power generation module to a power consumption device in the disconnected state;
a load module that internally consumes a portion of the power generated by the power generation module in the disconnected state,
the controller and the power conditioner are configured to operate in a grid-connected operation mode in the parallel state and to operate in an isolated operation mode in the disconnected state;
The controller, while operating in the standalone mode,
A power generation unit that adjusts the power consumption in the load module so that the effective output power of the independent outlet, which is the power generated by the power generation module minus the first power loss due to the operation of the load module, follows the power consumption of the power-using device. The power generating unit according to claim 1 , wherein the load module has at least a power consumption amount equivalent to a set available power supply amount when the power consuming device is not connected to the self-contained outlet. The controller, while operating in the standalone mode,
The power generation unit according to claim 2, wherein the power generation module is operated so as to obtain a generated power that is the sum of the available power supply, a second power loss due to operation of the auxiliary equipment, and a third power loss due to operation of the power conditioner. the power generation module includes a cell stack in which solid oxide fuel cells are integrated,
the auxiliary machinery includes a fluid transfer device for transferring fluid necessary for the power generation operation of the cell stack,
The power generating unit according to claim 3 , wherein the second power loss is a power loss caused by a change in the operating state of the fluid transfer device. 5. The power generating unit according to claim 1, wherein the load module comprises one selected from the group consisting of an electric heater, an electric resistance circuit, and a switching element.