Power generation system

Abstract

To operate a system while suppressing a decrease in power generation efficiency, and suppress the purchase of electricity from a commercial power grid and thereby suppress economic losses even when supplying generated power to equipment whose load fluctuates instantaneously in cycles of less than a second to several seconds.SOLUTION: A control device S maintains the power generated by a fuel cell device 10 at high setting power, which is higher than the power generated according to the minimum value of a load in instantaneous load fluctuations, and executes output reduction suppression control in which the surplus power that is not consumed by the device in the power generated by the fuel cell device 10 is consumed by a surplus power consumption unit 13 when it is determined that an instantaneous load fluctuation has occurred, which is an instantaneous load fluctuation of the device 16 when the control device S executes a load following operation in which the generated power of the fuel cell device 10 follows the load of the device 16.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power generation system including a fuel cell device that supplies generated power to equipment that generates load fluctuations, and a control device that controls the generated power of the fuel cell device. [Background technology]

[0002] Conventionally, for example, a power generation system has been known that includes a fuel cell device that supplies generated power to appliances that generate load fluctuations installed in a home, and a control device that controls the generated power of the fuel cell device (see Patent Document 1). In the power generation system shown in Patent Document 1, when reverse power flow is prevented, the control device performs load following operation, which changes the power generated by the fuel cell device in accordance with load fluctuations of the equipment, thereby reducing the amount of power purchased from the commercial power grid at the home. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-130572 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described power generation system, when the control device causes the fuel cell device to perform load following operation, and the load fluctuates between a maximum value Hi and a minimum value Lo as shown in FIG. 5, control (hereinafter sometimes abbreviated as control 1) may be executed to reduce the power generation of the fuel cell device by ΔL in response to a load reduction of ΔL. Here, in a fuel cell device, although the power generation can be reduced instantaneously, when the power generation is increased, it is necessary to increase the amount of hydrogen produced as fuel, and so the power generation can only be increased gradually. For this reason, when the load changes frequently at relatively short intervals, the power generation of the fuel cell device drops to zero in the above-mentioned Control 1, as shown in Figure 5, and after the frequent load changes, a problem occurs in which a discrepancy occurs between the load and the power generation for a certain period of time. Here, load fluctuations that occur frequently at relatively short time intervals refer to load fluctuations that occur in cycles of less than one second to several seconds, and examples of equipment that cause such load fluctuations include toilet seats, rice cookers, and electric stoves.

[0005] On the other hand, as shown in Fig. 6, when the control device causes the fuel cell device to perform load following operation and the load fluctuates between a maximum value Hi and a minimum value Lo, control (hereinafter sometimes abbreviated as Control 2) may be executed to make the power generated by the fuel cell device follow the minimum value Lo of the load as the load decreases. When Control 2 is executed, the power generated by the fuel cell device does not decrease to zero, but if load fluctuations occur frequently at relatively short time intervals, a deviation will occur between the load and the power generated for a certain period of time after the frequent load fluctuations, similar to Control 1 above. Thus, whether load following operation is performed under control 1 or 2, as long as there is a discrepancy between the load and the generated power, the power generation efficiency may decrease due to operation at a generated power that is significantly lower than the rated power, or the power generation may not be sufficient to meet the load, which may result in the need to purchase power from the commercial power grid, causing unnecessary economic losses for each household, and there is room for improvement.

[0006] The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a power generation system that can operate while suppressing a decrease in power generation efficiency, even when supplying generated power to equipment whose load fluctuates instantaneously in cycles of less than one second to several seconds, and that can reduce the amount of power purchased from the commercial power grid and suppress the resulting economic loss. [Means for solving the problem]

[0007] The power generation system for achieving the above object is a power generation system including a fuel cell device that supplies generated power to equipment that generates load fluctuations, and a control device that controls the generated power of the fuel cell device, and the system has the following characteristic configuration: a load detection means for detecting a load of the device; When the control device determines that an instantaneous load fluctuation, which is an instantaneous load fluctuation of the device, has occurred while performing a load following operation in which the generated power of the fuel cell device follows the load of the device, the control device maintains the generated power of the fuel cell device at a high set generated power which is higher than the generated power that matches the minimum value of the load in the instantaneous load fluctuation, and executes output reduction suppression control in which surplus power not consumed by the device out of the generated power generated by the fuel cell device is consumed by a surplus power consumption unit. and the control device determines the occurrence of the instantaneous load fluctuation during a predetermined instantaneous load fluctuation determination period, The control device sets the high set generated power higher as the proportion of time during which the high load is present in the instantaneous load fluctuation determination period during which the occurrence of the instantaneous load fluctuation is determined increases. It's at the point.

[0008] According to the above characteristic configuration, when the control device is performing load-following operation in which the power generated by the fuel cell device follows the load of the equipment, and when it determines that an instantaneous load fluctuation has occurred, the control device maintains the power generated by the fuel cell device at a high-setting power output that is higher than the power generated at the minimum value of the load in the instantaneous load fluctuation, and executes output reduction suppression control in which the surplus power generated by the fuel cell device that is not consumed by the equipment is consumed by the surplus power consumption unit. Therefore, even if the instantaneous load fluctuation continues, the power generated by the fuel cell device can be prevented from decreasing too much. Furthermore, immediately after the instantaneous load fluctuation, the power generated follows the load from the high-setting power output, which is a relatively high power output, so the difference between the load and the power generated can be made smaller than before, and the amount of power purchased from the commercial power grid can be reduced, thereby suppressing the resulting economic loss. Furthermore, it is possible to prevent the fuel cell from being operated at a power generation level that is significantly lower than the rated power, thereby realizing operation in which a decrease in power generation efficiency is suppressed. Here, instantaneous load fluctuations are load fluctuations that occur in cycles of less than one second to several seconds, and examples of equipment that cause such load fluctuations include toilet seats, rice cookers, and electric stoves. The greater the proportion of time during which a high load occurs during the instantaneous load fluctuation determination period during which the occurrence of an instantaneous load fluctuation is determined, the higher the possibility that a high load will occur after the instantaneous load fluctuation ends. According to the above characteristic configuration, the higher the proportion of time under high load during the instantaneous load fluctuation judgment period, the higher the high-set power generation power is set, so that when a load fluctuation occurs or immediately afterwards, the power generation can be made to follow the high load in a relatively short time. On the other hand, when the proportion of time during which the load is high during the instantaneous load fluctuation determination period in which the occurrence of an instantaneous load fluctuation is determined is low, the high set power generation power is set low, thereby preventing the power generation power from becoming higher than necessary for the load.

[0013] Further characteristic configurations of the power generation system include: The control device estimates the time proportion Rth of the high load during the instantaneous load fluctuation judgment period based on the following equation (1) using the maximum value Hi of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period, the minimum value Lo of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period, and the average value Av of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period. Rth=(Av-Lo) / (Hi-Lo) [Formula 1]

[0014] As described above, in order to set an appropriate high set generated power, it is preferable to set it based on the proportion of time during which the load is high during the instantaneous load fluctuation determination period. To achieve this, it is necessary to have a high-precision flow meter (load meter) that can accurately detect load fluctuations that occur in cycles of less than one second to several seconds, but currently, due to economic reasons and other reasons, it is often not possible to have such a high-precision flow meter. According to the above characteristic configuration, the time proportion of high load during the instantaneous load fluctuation judgment period is estimated based on the above-mentioned [Equation 1] from the maximum value Hi, minimum value Lo, and average value Av of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period. Therefore, even in a configuration that does not have a high-precision flow meter, the time proportion of high load during the instantaneous load fluctuation judgment period can be obtained and the high set power generation power can be appropriately set based on this value.

[0015] Further characteristic configurations of the power generation system include: The control device estimates the time proportion Rth of high load during the instantaneous load fluctuation judgment period by taking into account not only the time proportion Rth of high load estimated based on the instantaneous load fluctuation during the instantaneous load fluctuation judgment period immediately preceding the current time, but also the maximum value Hi, the minimum value Lo, and the average value Av during the past instantaneous load fluctuation judgment period, or the time proportion Rth of high load estimated based on the instantaneous load fluctuation during the past instantaneous load fluctuation judgment period.

[0016] According to the above characteristic configuration, the time percentage of high load is estimated while taking into account the instantaneous load fluctuations during past instantaneous load fluctuation judgment periods and the time percentage of high load estimated based on the instantaneous load fluctuations.Therefore, the time percentage of high load can be estimated in a state that more appropriately reflects the installation environment of the power generation system, etc., and the high set power generation power can be appropriately set based on the time percentage of high load.

[0017] Further characteristic configurations of the power generation system include: the device and the fuel cell device are configured to be interconnectable with a grid; The control device controls the power generated by the fuel cell device so as to prevent reverse power flow when the system is connected to the grid.

[0018] The effects of the power generation system described above are effectively exhibited in a configuration in which the power generated by the fuel cell device is controlled so as to prevent reverse power flow. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic configuration diagram of a power generation system according to an embodiment. [Figure 2] FIG. 2 is a control flow diagram of the power generation system according to the embodiment. [Figure 3] FIG. 10 is a diagram for explaining the proportion of time during which a high load is applied in an instantaneous load fluctuation determination period. [Figure 4] FIG. 10 is a graph for setting a high set power generation output from the time ratio of a high load. [Figure 5]FIG. 10 is a graph showing the power generated by the fuel cell device when performing conventional load following operation. [Figure 6] FIG. 10 is a graph showing the power generated by the fuel cell device when performing conventional load following operation. DETAILED DESCRIPTION OF THE INVENTION

[0020] The power generation system 100 according to an embodiment of the present invention is capable of operating while suppressing a decrease in power generation efficiency even when supplying generated power to equipment whose load fluctuates instantaneously in cycles of less than one second to several seconds, and is capable of reducing the amount of power purchased from the commercial power grid and suppressing the resulting economic losses.

[0021] A power generation system 100 according to an embodiment will be described below with reference to FIGS. As shown in FIG. 1, the power generation system 100 according to the embodiment includes a fuel cell device 10 that supplies generated power to a load 16 (an example of equipment) that causes load fluctuations, and a control device S (part of the fuel cell device 10) that controls the generated power of the fuel cell device 10.

[0022] The fuel cell device 10 is configured to include a fuel cell main body 11 that uses natural gas (city gas 13A) as fuel and outputs DC power to a DC output line DC1, a power conditioner 12 that converts the DC power of the fuel cell main body 11 into AC power of a predetermined electrical output voltage and frequency and outputs it to an AC output line AC1, and a control device S that controls the power generated by the fuel cell main body 11. The fuel cell device 10 is provided with a heater 13 (an example of a surplus power consumption section) that can consume part of the power generated by the fuel cell main body 11, and the heater 13 is connected to the AC output line AC1 by a consumption AC line AC4 via a heater control device 14 that controls the power consumption of the heater 13. The control device S controls the power consumption of the heater 13 by sending a control command to the heater control device 14. In this embodiment, the power conditioner 12 converts the output voltage of the fuel cell main body 11 into a single-phase three-wire sine wave output of 100V / 200V for general household use, outputs it to an AC output line AC1, and supplies it to a load 16 via a load AC line AC2. In addition, the fuel cell device 10 is connected to a grid power supply (commercial AC power supply) 15, and the load 16 receives AC power of the same electrical system from the grid power supply 15. Therefore, the power conditioner 12 has a function of connecting to the grid power supply 15. Furthermore, the fuel cell device 10 functions as a combined heat and power supply device that heats a heat medium (such as water) by heat exchange with the exhaust heat of the fuel cell main body 11 and supplies the heat medium to an exhaust heat utilization hot water supply and heating unit (not shown). Incidentally, although not shown, the exhaust heat utilization hot water supply and heating unit is composed of a hot water storage tank, auxiliary heat source, electric heater, heat exchanger, etc., and is configured to receive heat supply from the fuel cell device 10 to supply hot water to the bathtub, bathroom, kitchen, etc. in the home, and to circulate hot water for heating each room. However, since the specific configuration is not directly related to the gist of the present invention, a detailed description thereof will be omitted.

[0023] In addition to the above configuration, in order to monitor the load power used to control the fuel cell device 10, a second ammeter (current transformer) CT2 (an example of a load detection means) is provided on the AC output line AC1, which is the output end of the fuel cell main body 11, and a first ammeter (current transformer) CT1 (an example of a load detection means) is provided on the system AC line AC3 on the system power source 15 side of the junction of the output power of the fuel cell main body 11 and the system power of the system power source 15, so that the output power Px of the fuel cell device 10 and the system power Py of the system power source 15 can be measured individually and the load power Pz consumed by the load 16 can be derived from the sum of these. Although not shown, the voltage values ​​on the AC output line AC1 and the system AC line AC3 can be measured as being equal to each other, and are used to measure the output power Px and the system power Py, respectively.

[0024] 1, it is necessary to provide an islanding prevention device and a protective relay that comply with the grid interconnection guidelines to protect the grid, and for example, a specified protective relay that disconnects the power as soon as a grid power outage is detected must be provided between the power conditioner 12 of the fuel cell device 10 and the grid power source 15. However, the protective relay may be located within the fuel cell device 10, and is not shown in the drawings in this embodiment as it is not relevant to the main purpose of the present invention. Incidentally, in the power generation system 100 according to this embodiment, the control device S controls the power generated by the fuel cell device 10 and the power consumption of the heater 13 (reverse flow prevention control) to prevent reverse power flow from the fuel cell device 10 to the system power source 15. Here, the control device S performs load-following operation in which the generated power follows the load with the target value being "load," "load minus a predetermined value," or "a predetermined value less than load x 1." When the load fluctuates between a maximum value Hi and a minimum value Lo, as shown in FIG. 5, the control device S executes control to reduce the generated power of the fuel cell device 10 by ΔL in response to a load reduction of ΔL. Alternatively, the control device S performs load-following operation in which the generated power follows the load using the target values ​​of "load," "load minus a predetermined value," or "a predetermined value less than load x 1," and when the load fluctuates between the maximum value Hi and the minimum value Lo, it performs control (hereinafter sometimes abbreviated as control 2) in which the generated power of the fuel cell device 10 follows the minimum value Lo of the load in response to a decrease in the load.

[0025] Now, in the power generation system 100 according to this embodiment, in order to prevent a situation in which the power generation efficiency of the fuel cell device 10 is significantly reduced relative to the load when momentary load fluctuations occur continuously, the power generation system 10 is configured as follows. That is, when the control device S is performing load following operation in which the power generated by the fuel cell device 10 follows the load 16, and determines that an instantaneous load fluctuation, which is an instantaneous load fluctuation of the load 16, has occurred, the control device S maintains the power generated by the fuel cell device 10 at a high set power generation level, which is higher than the power generation level adjusted to the minimum value of the load in the instantaneous load fluctuation, and executes output reduction suppression control in which the surplus power generated by the fuel cell device 10 that is not consumed by the load 16 is consumed by the heater 13.

[0026] Here, the generated power of the fuel cell device 10 refers to the generated power generated by the fuel cell main body 11. Furthermore, load following operation refers to an operation in which the generated power of the fuel cell device 10 follows the load, for example, as shown in Fig. 5, and when the load decreases, the generated power is instantaneously decreased by an amount equal to the load decrease width ΔL, and when the load increases, the generated power is gradually increased so that the load and the generated power become equal. Note that the load following operation according to this embodiment also includes an operation in which the minimum value of the generated power of the fuel cell main body 11 is made approximately equal to the minimum value of the load, as shown in Fig. 6.

[0027] An instantaneous load fluctuation is a load fluctuation that occurs in a cycle of less than one second to several seconds, and examples of equipment that generates such load fluctuations include toilet seats, rice cookers, and electric stoves. Furthermore, in the domestic power generation system 100, from an economical standpoint, it is difficult to provide the first ammeter CT1 and second ammeter CT2 with high accuracy that can detect load fluctuations that occur in cycles of less than one second to several seconds. Therefore, the control device S determines the occurrence of instantaneous load fluctuations by the following control. That is, when the control device S is performing load following operation, if the load of the device as the load 16 is greater than the power generated by the fuel cell device 10 by a predetermined criterion width or more, the control device S determines that an instantaneous load fluctuation has occurred. Here, the predetermined criterion width means, for example, a width of 50 W or more and 700 W or less when the power generation system 100 is for home use. This determination is made under the prerequisite that, when the power generation system 100 is installed in a home, the power load in the home is equal to or less than the maximum power generation power of the fuel cell device 10, and the power generation power of the fuel cell device 10 has not reached the power generation suppression control state that suppresses power generation.

[0028] Next, a method for setting the high set generated power in the output reduction suppression control will be described. As shown in Figures 3 and 4, the control device S determines the occurrence of an instantaneous load fluctuation during a predetermined instantaneous load fluctuation determination period Ts, and sets the high-set power generation power higher as the high-load time ratio Rth during the instantaneous load fluctuation determination period Ts in which the occurrence of an instantaneous load fluctuation is determined increases. More specifically, the control device S estimates the time proportion Rth of high load during the instantaneous load fluctuation judgment period Ts based on the following Equation 1 using the maximum value Hi of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period Ts, the minimum value Lo of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period Ts, and the average value Av of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period.

[0029] Rth=(Av-Lo) / (Hi-Lo) [Formula 1]

[0030] For example, if Av=550W, Hi=650W, and Lo=400W, Rth is 0.6 (60%). The greater the time ratio Rth of high load during the instantaneous load fluctuation determination period Ts during which the occurrence of an instantaneous load fluctuation is determined, the higher the possibility that a high load will occur after the instantaneous load fluctuation ends. Therefore, by setting the high set power generation power based on the time ratio Rth of high load during the instantaneous load fluctuation determination period Ts, the power generation can be made to smoothly follow the load after the instantaneous load fluctuation ends. However, in order to calculate the time ratio Rth of high load during the instantaneous load fluctuation judgment period Ts, it is necessary to provide a high-precision flow meter (load meter) that can accurately detect load fluctuations that occur in cycles of less than one second to several seconds, but currently, it is often not possible to provide such a high-precision flow meter due to economic reasons, etc. Therefore, by estimating the time proportion Rth of high load during the instantaneous load fluctuation judgment period Ts based on the maximum value Hi, minimum value Lo, and average value Av of the instantaneous load fluctuation during the instantaneous load fluctuation judgment period Ts based on the above-mentioned [Equation 1], even in a configuration that does not have a high-precision flow meter, the time proportion Rth of high load during the instantaneous load fluctuation judgment period Ts can be obtained, and the high-set power generation power can be appropriately set based on this value.

[0031] The control device S can also estimate the high load time ratio Rth based on various values ​​acquired in the past prior to the instantaneous load fluctuation determination period Ts immediately preceding the present time. For example, as shown in FIG. 3, the control device S can set the high set power generation power based on the time ratio Rth of high load estimated in a period K including the instantaneous load fluctuation determination period Ts immediately before the current time. However, the control device S may also be configured to set the high set power generation power by taking into account the time ratio Rth of high load estimated in the instantaneous load fluctuation determination period Ts in a past period (K-1, K-2, K-3, etc. in FIG. 3) prior to the period K.

[0032] For example, the high power generation setting may be set based on a weighted average of the high load time ratios Rth for a plurality of instantaneous load fluctuation determination periods Ts, with the weighted average being weighted so that the closer to the current time point the greater the influence. Alternatively, the high power generation setting may be set simply based on the average value of the high load time ratios Rth for a plurality of instantaneous load fluctuation determination periods Ts.

[0033] Here, the control device S stores a graph (for example, f1, f2, and f3 in FIG. 4) or a map showing the relationship between the estimated high load time ratio Rth and the high set power generation, as shown in FIG. 4, and determines the high set power generation between the maximum load value Hi and the minimum load value Lo in the instantaneous load fluctuation determination period Ts used for the estimation from the high load time ratio Rth. The graph is determined appropriately taking into account factors such as power generation efficiency, and has a relationship in which the higher the high load time ratio Rth, the higher the high set power generation. Note that graphs f1, f2, and f3 in FIG. 4 are graphs having a positive correlation as the relationship between the high load time ratio Rth and the high set generated power.

[0034] The control flow of the power generation system 100 according to this embodiment will be described with reference to FIG. When the fuel cell device 10 starts generating power, the control device S executes a load following operation in which the power generated by the fuel cell device 10 follows the load of the load 16 (#01).

[0035] Next, the control device S determines whether the instantaneous load fluctuation occurrence condition is satisfied, that is, whether the load of the device as the load 16 is greater than the power generated by the fuel cell device 10 by a predetermined judgment criterion width or more while the load following operation is being performed. If it is greater (Yes in #02), the control device S proceeds to step #03. If it is not greater (No in #02), the control device S continues the load following operation of #01. Note that the determination in #02 is performed when the above-mentioned preconditions are satisfied. . Here, the precondition means that, as described above, when the power generation system 100 is installed in a home, the power load in the home is less than the maximum power generation power of the fuel cell device 10, and the power generation power of the fuel cell device 10 has not reached the power generation suppression control state that suppresses power generation.

[0036] If the answer to #02 is Yes, the control device S estimates the time ratio Rth of high load during the instantaneous load fluctuation determination period Ts based on [Equation 1] (#03), derives the high set power generation power based on the time ratio Rth of high load based on the graph shown in Figure 4 or the like (#04), and executes output reduction suppression control based on the derived high set power generation power (#05). That is, in the output reduction suppression control, the control device S maintains the power generated by the fuel cell device 10 at a high set power generation level, which is higher than the power generation level adjusted to the minimum value of the load in the instantaneous load fluctuation, and when the load becomes low instantaneously, the control device S controls the power generated by the fuel cell device 10 so that the surplus power not consumed by the load 16 is consumed by the heater 13, thereby preventing reverse power flow.

[0037] While the output decrease suppression control is being executed, the control device S again determines whether the instantaneous load fluctuation occurrence condition is satisfied (#06). That is, while the control device S is executing the load following operation, the control device S determines whether the load of the device as the load 16 is greater than the power generated by the fuel cell device 10 by a predetermined judgment reference width or more, and if it is greater (Yes in #06), the control device S continues the output decrease suppression control (#07), and if it is not greater (No in #06), the control device S transitions to the load following operation of #01.

[0038] [Another embodiment] (1) In the power generation system 100 according to the above embodiment, a data logger (a device for monitoring the amount of power with high accuracy) that measures power may be provided as a device for detecting whether or not a load 16 (an example of equipment) that causes momentary load fluctuations is present. The control device S may be configured to determine the occurrence of an instantaneous load fluctuation in the load 16 during output reduction suppression control when the data logger detects that a load 16 that causes an instantaneous load fluctuation has been connected to the load AC line AC2. That is, the control device S may be configured not to determine whether an instantaneous load fluctuation has occurred in the load 16 if the data logger does not detect that a load 16 that causes an instantaneous load fluctuation has been connected to the load AC line AC2.

[0039] (2) In the above embodiment, when the control device S is performing load following operation, if the load of the device as the load 16 is greater than the power generated by the fuel cell device 10 by more than a predetermined judgment criterion range (for example, a value between 50 W and 700 W), the control device S determines that an instantaneous load fluctuation has occurred. As another control example, when the control device S is performing load following operation, if the load on the load 16 as an equipment is greater than or equal to the value obtained by multiplying the power generated by the fuel cell device 10 by a predetermined judgment reference value of 1 or more, the control device S may determine that an instantaneous load fluctuation has occurred.

[0040] (3) In the above embodiment, as shown in FIG. 3, the control device S can set the high set power generation power based on the time ratio Rth of high load estimated in a period K including the instantaneous load fluctuation determination period Ts immediately before the current time. However, for example, a configuration example is shown in which the high set power generation power is set taking into account the time ratio Rth of high load estimated in the instantaneous load fluctuation determination period Ts in a past period (K-1, K-2, K-3, etc. in FIG. 3) prior to the period K. As another configuration example, when calculating the time proportion Rth of high load estimated in the period K including the instantaneous load fluctuation judgment period Ts immediately before the current time, the control device S may estimate the high load by taking into account the maximum value Hi, minimum value Lo, and average value Av in past instantaneous load fluctuation judgment periods Ts.

[0041] (4) The high set power generation may be set to the power generation immediately before the instantaneous load fluctuation determination period Ts in which it is determined that the instantaneous load fluctuation has occurred.

[0042] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0043] The power generation system of the present invention can be effectively used as a power generation system that can operate while suppressing a decrease in power generation efficiency, even when supplying generated power to equipment whose load fluctuates instantaneously in cycles of less than one second to several seconds, and can reduce the amount of power purchased from the commercial power grid and thereby suppress the resulting economic loss. [Explanation of symbols]

[0044] 10:Fuel cell device 13: Heater 15: Grid power supply 16: Load 100: Power generation system CT1: 1st ammeter CT2: 2nd ammeter Hi: Maximum value Lo: Minimum value Rth: Time ratio S: Control device Ts: Instantaneous load fluctuation judgment period

Claims

1. A power generation system including a fuel cell device that supplies generated power to a device that generates load fluctuations, and a control device that controls the generated power of the fuel cell device, a load detection means for detecting a load of the device; When the control device determines that an instantaneous load fluctuation, which is an instantaneous load fluctuation of the device, has occurred while performing a load following operation in which the generated power of the fuel cell device follows the load of the device, the control device maintains the generated power of the fuel cell device at a high set generated power which is higher than the generated power matched to the minimum value of the load in the instantaneous load fluctuation, and executes output reduction suppression control in which surplus power not consumed by the device out of the generated power generated by the fuel cell device is consumed by a surplus power consumption unit; and the control device determines the occurrence of the instantaneous load fluctuation during a predetermined instantaneous load fluctuation determination period, The control device sets the high set power generation power higher as the proportion of time under high load during the instantaneous load fluctuation determination period in which the occurrence of the instantaneous load fluctuation is determined increases.

2. The power generation system of claim 1, wherein the control device estimates the time ratio Rth of the high load during the instantaneous load fluctuation determination period based on the following formula 1 using the maximum value Hi of the instantaneous load fluctuation during the instantaneous load fluctuation determination period, the minimum value Lo of the instantaneous load fluctuation during the instantaneous load fluctuation determination period, and the average value Av of the instantaneous load fluctuation during the instantaneous load fluctuation determination period. Rth=(Av-Lo) / (Hi-Lo) [Formula 1]

3. 3. The power generation system according to claim 2, wherein the control device estimates the time ratio Rth of high load during the instantaneous load fluctuation judgment period by taking into account, in addition to the time ratio Rth of high load estimated based on the instantaneous load fluctuation during the instantaneous load fluctuation judgment period immediately preceding the current time, the maximum value Hi, the minimum value Lo, and the average value Av during the past instantaneous load fluctuation judgment period, or the time ratio Rth of high load estimated based on the instantaneous load fluctuation during the past instantaneous load fluctuation judgment period.

4. the device and the fuel cell device are configured to be interconnectable with a grid; 4. The power generation system according to claim 1, wherein the control device executes reverse flow prevention control to prevent reverse flow of power generated by the fuel cell device during the grid connection.

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