JP5378252B2 - FUEL CELL SYSTEM AND METHOD FOR SETTING GENERATED POWER TARGET VALUE - Google Patents

Description

  The present invention relates to a fuel cell system, and more particularly to a control technique of generated power according to demand.

  A household fuel cell system (power generation unit) includes a hydrogen production apparatus including a reformer that reforms hydrocarbon fuel (for example, city gas, LPG, kerosene) to generate hydrogen, Generated by a fuel cell (fuel cell stack) that generates direct-current power from oxygen in the air by an electrochemical reaction, a power conditioner that includes an inverter that converts direct-current power generated by the fuel cell into alternating-current power, and a fuel cell It includes a heat exchanger that recovers heat and exchanges heat with the hot water supply unit side.

  In the fuel cell system, the power generated by the fuel cell cannot be supplied beyond the power demand to the user. For this reason, in the fuel cell systems described in Patent Documents 1 and 2, the generated power of the fuel cell is sequentially changed according to the demand power, and a storage battery is provided in the system in order to compensate for the followability of the power generation of the fuel cell. doing.

Japanese Patent Laid-Open No. 2003-075507 JP 2008-152959 A

  However, since the fuel cell system having a reformer is a system that adjusts the generated power by controlling the amount of fuel and water supplied, it is difficult to adjust the generated power as compared to other power generation systems. Therefore, when the generated power of the fuel cell is made to follow the demand power, the rate of change of the generated power of the fuel cell is slow. For example, until the generated power of the fuel cell decreases when the demand power suddenly decreases There is a problem that it takes time and excessive power is generated.

When surplus power is generated, it is necessary to consume the surplus power with an electric heater inside the system and convert it into heat in order to prevent reverse power flow, but it is necessary to convert it into heat using electricity generated from fuel. Therefore, the efficiency is lower than when the fuel is directly converted into heat by combustion or the like.
In other words, when power generation is performed following demand fluctuations that are subject to significant local fluctuations, there is a problem that the power generation efficiency decreases as a result, and fluctuations in the power generation output are the operational stability of the fuel cell stack and fuel reformer. , Become a negative factor for life.

Even in a fuel cell system using pure hydrogen without providing a reformer, a delay in hydrogen supply control occurs, which becomes a negative factor for the life of the fuel cell stack.
For this purpose, it is desirable to suppress excessive fluctuations in the power generation output.
Further, in the method using a storage battery, the storage battery itself has a high cost, a large size, and a low life, which greatly affects the cost, size, and life of the system.

  The present invention has been made to solve such a problem, and can reduce the generation of surplus power, suppress the decrease in power generation efficiency of the fuel cell, and increase the demand power rapidly. It aims at providing the fuel cell system which can respond also.

In order to solve the above-described problems, the present invention provides a control device for controlling the power generated by a fuel cell, based on the minimum value of the demand power within the evaluation time for each predetermined evaluation time. A generated power target value setting means for setting a target value of power is provided, and the generated power of the fuel cell is controlled according to the target value.
Further, the evaluation time is set based on the relationship between the demand power and the target value of the generated power, and in the demand power increase state where the demand power exceeds the target value of the generated power by a predetermined value or more, the evaluation time An evaluation time variable means for shortening the time is provided.

Further, when it is assumed that the evaluation time is variable at least between the first evaluation time and the second evaluation time, it can be described as follows.
According to the present invention, a target value for the generated power of the fuel cell is set in the control device for controlling the generated power of the fuel cell based on the minimum value of the demand power within the first evaluation time for each first evaluation time. The first generated power target value setting means and the demand power increase state where the demand power exceeds the target value of the generated power by a predetermined value or more, instead of the first generated power target value setting means, Second power generation target value setting for setting a target value of power generated by the fuel cell based on a minimum value of demand power within the second evaluation time when a second evaluation time shorter than the evaluation time has elapsed. And means for controlling the generated power of the fuel cell according to the target value.

  In this case, the method for setting the generated power target value of the fuel cell system of the present invention is based on the lowest value of the demand power within the first evaluation time for each first evaluation time, and the target of the generated power of the fuel cell. In a demand power increase state in which the value is set and the demand power exceeds the target value of the generated power by a predetermined value or more, the second evaluation time is reached when the second evaluation time shorter than the first evaluation time has elapsed. The target value of the generated power of the fuel cell is set based on the minimum value of the demand power.

According to the present invention, the generated power target value is set based on the minimum value of the demand power within the evaluation time instead of using the demand power as it is as the target value of the generated power, so that the generation of surplus power can be reduced. At the same time, even if the demand power fluctuates, the influence of the fluctuation can be eliminated, the fluctuation of the generated power can be moderated, and the decrease in the power generation efficiency can be suppressed by the stable operation.
In addition, if the evaluation time is variable and there is a sudden increase in demand power, the evaluation time can be shortened to change the target value of generated power relatively early and prevent loss of power generation opportunities. .

1 is a schematic configuration diagram of a fuel cell system showing an embodiment of the present invention. Flow chart of generated power target value (target output) setting routine Flowchart of generated power target value (target output) setting routine shown as another embodiment Explanatory drawing of conventional control Explanatory drawing of control in the flow of FIG. Explanatory drawing of control in the flow of FIG.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a schematic configuration diagram of a fuel cell system (power generation unit) showing an embodiment of the present invention.
A household fuel cell system (power generation unit) includes a hydrogen production device 2, a fuel cell 3, a power conditioner (PCS) 4, and a heat exchanger 5 in a system housing 1.

  The hydrogen production apparatus 2 generates hydrogen (hydrogen-rich fuel gas containing H2 and CO2) by reforming a hydrocarbon-based fuel (for example, city gas, LPG, kerosene, etc.) using a reforming catalyst while supplying steam. The main component is a reformer. In addition, a combustor (burner) 6 for heating a reformer for a reforming reaction (endothermic reaction) is provided. In the combustor 6, off-gas on the fuel electrode side of the fuel cell 3 (burner fuel before off-gas generation) To burn.

Although not shown, the hydrogen production device 2 is also provided upstream of the reformer, and adsorbs or removes sulfur compounds contained in the hydrocarbon-based fuel before reforming using an adsorbent. A desulfurizer that converts and removes using a catalyst, and a CO shift reactor that is provided downstream of the reformer and that converts by-product CO in the reformed gas to residual steam by a shift catalyst to convert it into CO2 and H2. Is provided.
In addition, if necessary, a CO selective oxidizer that selectively oxidizes CO slightly remaining in the gas after the shift reaction under the supply of air using a selective oxidation catalyst to CO 2 may be further provided.

  The fuel cell 3 is, for example, a polymer electrolyte (PEFC) fuel cell stack, and is configured by stacking a plurality of battery cells. The battery cell includes a fuel electrode (anode), an air electrode (cathode), and an electrolyte layer (polymer ion exchange membrane) disposed therebetween. Therefore, in the fuel cell 3, hydrogen (hydrogen-rich fuel gas) is supplied to the fuel electrode on one end side of the electrolyte layer, and oxygen in the air is supplied to the air electrode on the other end side of the electrolyte layer. Direct current power is generated by an electrochemical reaction (exothermic reaction) between oxygen and oxygen. The fuel cell 3 is not limited to a solid polymer type (PEFC), but is a phosphoric acid type (PAFC), a molten carbonate type (MCFC), a solid oxide type (SOFC), or an alkaline electrolyte type (AFC). Other types of fuel cells may be used.

  The power conditioner (PCS) 4 is mainly configured by an inverter that converts DC power generated in the fuel cell 3 into AC power and supplies the AC power to a household electrical device (load) EI. Further, the power conditioner 4 is provided with a surplus power heater 7, and when the power generated by the fuel cell 3 exceeds the demand power of the electric equipment EI, the DC power before conversion by the inverter or after conversion is used to prevent reverse power flow. A part of the AC power is supplied to the surplus power heater 7 and the surplus power is consumed. When the generated power of the fuel cell 3 is less than the demand power of the electric device EI, auxiliary power from the commercial power system CE is supplied to the electric device EI.

The heat exchanger 5 has a primary side that constitutes a part of the cooling water circulation passage 8 for cooling the fuel cell 3, and a secondary side that constitutes a part of the heat recovery passage 12 on the hot water supply unit (hot water storage unit) side. The heat generated in the battery 3 is recovered and heat exchanged with the hot water supply unit.
In the cooling water circulation passage 8 on the primary side of the heat exchanger 5, the water in the water tank 9 is sent to the cooler (water jacket) 11 of the fuel cell 3 by the water pump 10, and the water whose temperature is raised here is sent to the heat exchanger 5. The water is exchanged with the water from the hot water supply unit and then returned to the water tank 9. Although not shown, this cooling water is also used for cooling the exothermic reaction in the CO shift reactor and the CO selective oxidizer in the hydrogen production apparatus 2.

Further, the surplus power heater 7 is disposed in the heat recovery passage 12 on the secondary side of the heat exchanger 5 to recover heat when the surplus power is consumed.
Note that water necessary for reforming is supplied to the hydrogen production apparatus (reformer) 2, and at least a part of this water is in the off-gas on the air electrode side of the fuel cell 3 and / or the combustor 6. It is recovered from the exhaust gas by a condenser.

The fuel cell system (power generation unit) is also configured to include a control device 13 that controls the generated power of the fuel cell 3 in accordance with the demand power of the electric equipment EI. The control device 13 is configured by a microcomputer and includes a CPU, a ROM, a RAM, an input / output interface, and the like.
Signals are input to the control device 13 from the measuring instruments 14 and 15 for the control according to the demand power of the electric equipment EI. The measuring instrument 14 measures the supplied power supplied from the fuel cell 3 to the electric device EI and outputs a measured value of the supplied power to the control device 13. The measuring instrument 15 measures auxiliary power supplied from the commercial power system CE to the electrical equipment EI and outputs a measured value of auxiliary power to the control device 13. The demand power of the electrical equipment EI is calculated as the sum of the supplied power and the auxiliary power.

In addition, a signal is input to the control device 13 from a measuring instrument 16 such as an ammeter built in the fuel cell 3, and based on this, the actual generated power of the fuel cell 3 can be detected.
The control of the generated power by the control device 13 is to supply the reformed fuel to the fuel cell 3 by controlling the amount of fuel supplied to the hydrogen production device 2 via the fuel supply control means (pump and / or control valve) 17. The amount is controlled, and the amount of air supplied to the fuel cell 3 is controlled via an air supply control means (pump and / or control valve) 18. Actually, in addition to this, supply of reforming water to the hydrogen production apparatus (reformer) 2, supply of fuel to the combustor 6, supply of air to the CO selective oxidizer, supply of cooling water to each part, etc. Control cooperatively.

Therefore, the control device 13 sets the generated power target value of the fuel cell 3 according to the demand power of the electric equipment EI, and according to this (to obtain the generated power target value), the fuel supply amount, the air supply amount, etc. By controlling this, the power generated by the fuel cell 3 is controlled.
The control device 13 also controls the power conditioner 4 to supply surplus power to the surplus power heater 7 when the generated power of the fuel cell 3 exceeds the demand power of the electric equipment EI. Thereby, hot water supply is performed using surplus electric power.

Next, the setting of the generated power target value (target output) of the fuel cell 3 according to the demand power of the electric equipment EI in the control device 13 in the present embodiment will be described in detail.
FIG. 2 is a flowchart of a generated power target value (target output) setting routine. This routine is started when the system is started, and is executed until it is determined that the system is stopped (finished) in S5 described later.

S1 to S4 are processes executed only at the start of this routine (immediately after system startup).
In S1, the first timer TM1 for counting the first evaluation time T1 is started (0 start). That is, the timing of the first evaluation time T1 is started. The first evaluation time T1 is about 10 to 15 minutes, for example.
In S2, the current demand power P is acquired.

In S3, a generated power target value (target output) P0 is set. Specifically, it is set to an arbitrary value (a value arbitrarily determined in advance) or a value (P-dP3) smaller than the current demand power P by a predetermined deviation dP3.
In S4, initial setting is performed as the minimum value Pmin1 = P (value acquired in S2) of the demand power within the first evaluation time T1.

After S5, the process is repeatedly executed during the execution of this routine.
In S5, it is determined whether or not the system is stopped (terminated). If No, the process proceeds to S6.
In S6, it is determined whether or not the first timer TM1 for counting the first evaluation time T1 has been started, that is, whether TM1 ≠ 0. If the first timer has not been started (if TM1 = 0), the process proceeds to S7, where the first timer TM1 is started (0 start). That is, the timing of the first evaluation time T1 is started.

In S8, the current demand power P is newly acquired.
In S9, it is determined whether or not the demand power P is lower than the generated power target value (target output) P0. If it is lower, the process proceeds to S10, and the generated power target value (target output) is avoided in order to avoid the generation of surplus power. P0 is updated as follows:
P0 = P-dP3
That is, the generated power target value (target output) P0 is set to a value (P−dP3) smaller than the demand power P by a predetermined deviation dP3.

In other words, when the target value of the generated power is larger than the demand power, the target value of the generated power is set to be smaller than the demand power by a predetermined deviation dP3.
After updating the generated power target value (target output) P0 in S10, the process proceeds to S11, and the first timer TM1 for counting the first evaluation time T1 and the second timer TM2 for counting the second evaluation time T2 After resetting (TM1 = 0, TM2 = 0), the process returns to S5. Therefore, the timing of the first evaluation time T1 is reset halfway and restarted (S7).

If the demand power P is higher than the generated power target value (target output) P0 in the determination in S9, the process proceeds to the minimum value determination and minimum value update processing in S12 and S13.
In S12, the current demand power P is compared with the lowest value Pmin1 so far within the first evaluation time T1, and if P <Pmin1, the process proceeds to S13, and the lowest value is updated with the lowest value Pmin1 = P. To do. After such minimum value update processing, the process proceeds to S14.

In S14, the value of the first timer TM1 is compared with the first evaluation time T1, and it is determined whether TM1 ≧ T1, that is, whether the first evaluation time T1 has elapsed.
When it is within the first evaluation time T1 (when TM1 <T1), the process proceeds to S17, and it is determined whether or not the demand power increase state (P-P0> dP1). The demand power increasing state refers to a state in which the demand power P exceeds the generated power target value (target output) P0 by a predetermined value dP1 or more. This predetermined value dP1 is set to about 200 W, for example.

If the demand power is not increased (No in S17), the process proceeds to S18, the second timer TM2 for measuring the second evaluation time T2 is reset (TM2 = 0), and then the process returns to S5.
If it is determined in S14 that the first evaluation time T1 has passed (when TM1 ≧ T1), the process proceeds to a target output update process in S15.
In S15, as shown in the following equation, a value (Pmin1-dP11) smaller than the minimum value Pmin1 of the demand power within the first evaluation time T1 by a predetermined deviation dP11 is set as a new generated power target value (target output) P0. To do.

P0 = Pmin1-dP11
After updating the generated power target value (target output) P0 in S15, the process proceeds to S16, and the first timer TM1 for counting the first evaluation time T1 and the second timer TM2 for counting the second evaluation time T2 After resetting (TM1 = 0, TM2 = 0), the process returns to S5.
Next, processing when there is a sudden increase in demand power P (for example, introduction of a new electric device) within the first evaluation time T1 will be described.

If the determination at S14 is within the first evaluation time T1 (when TM1 <T1), the process proceeds to S17.
In S17, it is determined whether or not the demand power increase state (P-P0> dP1) in which the demand power P exceeds the generated power target value (target output) P0 by a predetermined value dP1 or more.
Therefore, if there is a sudden increase in the demand power P, P−P0> dP1 is satisfied, so the determination in S17 is Yes and the process proceeds to S19.

In S19, it is determined whether or not the second timer TM2 for measuring the second evaluation time T2 has been started, that is, whether or not TM2 ≠ 0.
When the second timer has not been started (when TM2 = 0), the process proceeds to S20 and S21. In S20, the second timer TM2 for measuring the second evaluation time T2 is started (0 start). That is, the timing of the second evaluation time T2 is started. The second evaluation time T2 is set shorter than the first evaluation time T1. For example, if the first evaluation time T1 is 10 to 15 minutes, the second evaluation time T2 is about 1 to 2 minutes.

Moreover, in S21, it initializes as the minimum value Pmin2 = P (value acquired by S8) of the demand power in 2nd evaluation time T2. Thereafter, the process returns to S5.
Subsequently, when the process proceeds from S17 to S19 in the demand power increasing state (P−P0> dP1), the second timer has already been started (TM2 ≠ 0) in the determination of S19, so the lowest values of S22 and S23 Proceed to determination and minimum value update processing.

In S22, the current demand power P is compared with the previous minimum value Pmin2 within the second evaluation time T2, and if P <Pmin2, the process proceeds to S23, and the minimum value is updated with the minimum value Pmin2 = P. To do. After such minimum value update processing, the process proceeds to S24.
In S24, the value of the second timer TM2 is compared with the second evaluation time T2, and it is determined whether TM2 ≧ T2, that is, whether the second evaluation time T2 has elapsed.

When it is within the second evaluation time T2 (when TM2 <T2), the process returns to S5 as it is.
If the second evaluation time T2 has elapsed in the determination in S24 (when TM2 ≧ T2), the process proceeds to the target output update process in S25.
In S25, as shown in the following equation, a value (Pmin2-dP21) smaller than the minimum value Pmin2 of the demand power within the second evaluation time T2 by a predetermined deviation dP21 is set as a new generated power target value (target output) P0. To do.

P0 = Pmin2-dP21
Note that dP11 and dP21 may be the same value or different.
After updating the generated power target value (target output) P0 in S25, the process proceeds to S26, and the first timer TM1 for counting the first evaluation time T1 and the second timer TM2 for counting the second evaluation time T2 are counted. After resetting (TM1 = 0, TM2 = 0), the process returns to S5.

  Before the second evaluation time T2 elapses after the demand power sharply rises, the demand power increase state (P-P0> dP1) is determined in S17, and the second evaluation time T2 is started. On the other hand, if the demand power decreases and the demand power is not increased (P-P0> dP1) in S17, the process proceeds from S17 to S18. Accordingly, in S18, the second timer TM2 for measuring the second evaluation time T2 is reset (TM2 = 0), and then the process returns to S5. Therefore, as usual, the generated power target value (target output) P0 is updated every first evaluation time T1.

  FIG. 3 is a flowchart of a generated power target value (target output) setting routine shown as another embodiment (second embodiment assuming FIG. 2 is the first embodiment). Compared with the flow of FIG. 2, the processes of S14 to S16 and S18 are abolished, and the processes of S31 to S34 are provided as the processes in the case of No in the determination of S17. Therefore, with respect to the flow of FIG. 3, portions different from FIG. 2 will be mainly described.

The processes of S1 to S13 are the same, and after proceeding to S17 after determining the minimum value of the demand power and the minimum value updating process within the first evaluation time T1 in S12 and S13.
In S17, it is determined whether or not the demand power increase state (P-P0> dP1) in which the demand power P exceeds the generated power target value (target output) P0 by a predetermined value dP1 or more.
When the demand power is not increased (No in S17), the process proceeds to S31, the second timer TM2 for measuring the second evaluation time T2 is reset (TM2 = 0), and the process proceeds to S32.

In S32, the value of the first timer TM1 is compared with the first evaluation time T1, and it is determined whether TM1 ≧ T1, that is, whether the first evaluation time T1 has elapsed.
When it is within the first evaluation time T1 (when TM1 <T1), the process returns to S5.
If it is determined in S32 that the first evaluation time T1 has elapsed (when TM1 ≧ T1), the process proceeds to a target output update process in S33.

In S33, as shown in the following equation, a value (Pmin1-dP11) smaller than the minimum value Pmin1 of the demand power within the first evaluation time T1 by a predetermined deviation dP11 is set as a new generated power target value (target output) P0. To do.
P0 = Pmin1-dP11
After the generated power target value (target output) P0 is updated in S33, the process proceeds to S34, the first timer TM1 for counting the first evaluation time T1 is reset (TM1 = 0), and then the process returns to S5.

  For processing in the case where there is a sudden increase in demand power P (for example, the introduction of a new electric device), demand power in which demand power P exceeds a generated power target value (target output) P0 by a predetermined value dP1 or more in S17 It is determined whether or not it is in an increased state (P-P0> dP1), and if there is a sudden rise in demand power P, P-P0> dP1 is established, so the determination in S17 is Yes and the process proceeds to S19. The processing of S19 to S26 is the same.

  It should be noted that the demand power has risen rapidly and it is determined in S17 that the demand power has been increased (P-P0> dP1) and the second evaluation time T2 has elapsed after the second evaluation time T2 has started. If the demand power is reduced and the demand power is not increased (P-P0> dP1) in S17, the process proceeds from S17 to S31. Accordingly, in S31, the second timer TM2 for measuring the second evaluation time T2 is reset (TM2 = 0), and finally the process returns to S5. Therefore, as usual, the generated power target value (target output) P0 is updated every first evaluation time T1.

FIG. 4 is an explanatory diagram of conventional control, and FIGS. 5 and 6 are explanatory diagrams of control in the embodiment (first and second embodiments) of the present invention. In these figures, the demand power P is indicated by a thin line, the generated power target value (target output) P0 is indicated by a dotted line, the actual generated power (actual output) is indicated by a thick line, and the surplus power is indicated by hatching.
In the conventional control, as shown in FIG. 4, the generated power target value (target output) P0 is set according to the demand power P, and the actual generated power (actual output) is set to the generated power target value (≈demand It changes with a delay in the electric power P). Therefore, when the demand power P decreases, the generated power (actual output) does not fall in time, and surplus power (hatched portion) is generated.

  On the other hand, in the embodiment of the present invention, as shown in FIG. 5 or FIG. 6, for each first evaluation time T1, the generated power target value is based on the minimum value Pmin1 of the demand power within the time T1. (Target output) Since P0 is set, the generation of surplus power can be reduced, and even if the demand power P fluctuates, the influence of the fluctuation is eliminated and the fluctuation of the generated power (actual output) is moderated. In addition, a decrease in power generation efficiency can be suppressed by stable operation.

In addition, when there is a rapid increase in demand power P (for example, an increase of more than 200 W), the evaluation time is switched to the second evaluation time T2, and power generation is performed based on the minimum value Pmin2 of the demand power within the time T2. Since the power target value (target output) P0 is set, it is possible to change the generated power target value relatively early and prevent loss of power generation opportunities.
In addition, when the demand power P rapidly decreases and becomes lower than the generated power target value (target output) P0, the generated power target value (target output) P0 is immediately set to be smaller than the demand power P. By doing so, generation | occurrence | production of surplus electric power can be reduced.

Here, differences between the first embodiment (FIGS. 2 and 5) and the second embodiment (FIGS. 3 and 6) will be described.
In the first embodiment (FIG. 2), priority is given to time measurement / determination of the first evaluation time T1, and after the determination, determination of the demand power increase state (demand power surge), and therefore time measurement of the second evaluation time T2.・ Determine.

On the other hand, in the second embodiment (FIG. 3), determination of demand power increase state (demand power sudden increase) rather than time measurement / determination of the first evaluation time T1, that is, time measurement / determination of the second evaluation time T2. Prioritize judgment.
Therefore, when comparing at point A in FIGS. 5 and 6, in the first embodiment (FIG. 5), TM1 is prioritized, so TM2 count is interrupted, and P0 of the next cycle is calculated based on Pmin1. To do. On the other hand, in the second embodiment (FIG. 6), since TM2 is prioritized, TM2 continues counting even when TM1 elapses, and P0 of the next cycle is calculated based on Pmin2.

5 and FIG. 6, in the first embodiment (FIG. 5), since TM1 is prioritized, P0 of the next cycle is calculated based on Pmin1. On the other hand, in the second embodiment (FIG. 6), since TM2 is prioritized, P0 of the next cycle is calculated based on Pmin2.
As described above, according to the above embodiment, the control device 13 that controls the generated power of the fuel cell 3 is based on the minimum value of the demand power P within the evaluation time for each predetermined evaluation time. And a generated power target value setting means (S15 and S25, or S33 and S25) for setting the generated power target value P0 of 3 and controlling the generated power of the fuel cell 3 according to the target value P0. As a result, the generation of surplus power can be reduced, and the fluctuation of the generated power can be moderated regardless of the fluctuation of the demand power, thereby suppressing the decrease in power generation efficiency.

  The control device 13 further sets an evaluation time (T1 or T2) based on the relationship between the demand power P and the target value P0 of the generated power, and the demand power P sets the target value P0 of the generated power to a predetermined value. In the demand power increase state (P-P0> dP1 state) exceeding dP1 or more, by having an evaluation time variable means for shortening the evaluation time, if there is a sudden increase in demand power, it is relatively early The target value P0 of the generated power can be changed to prevent loss of power generation opportunities.

  In other words, the first generated power target value that sets the target value P0 of the generated power of the fuel cell based on the minimum value Pmin1 of the demand power P within the first evaluation time T1 for each first evaluation time T1. In the setting means (S15 or S33) and the demand power increasing state where the demand power P exceeds the target value P0 of the generated power by a predetermined value dP1 or more (state of P-P0> dP1), the first generated power target value Instead of the setting means, when the second evaluation time T2 shorter than the first evaluation time T1 has elapsed, the power generation of the fuel cell 3 is performed based on the minimum value Pmin2 of the demand power P within the second evaluation time T2. By having the second generated power target value setting means (S25) for setting the target value P0 of power, the generation time is reduced by reducing the generation of surplus power and mitigating fluctuations in the generated power by switching the evaluation time. Control, and has the advantages of loss prevention of generation opportunities when there is a sharp increase in the power demand.

  However, the switching of the evaluation time is not limited to two stages, and may be controlled in multiple stages based on the relationship between the demand power and the target value of the generated power. That is, according to the level of increase in demand power, the larger this is, the shorter the evaluation time may be. In the flowchart, it is preferable that the evaluation time T1 is constant and the evaluation time T2 is variable in a plurality of stages according to the level of increase in demand power (P-P0 level).

In addition, according to the above embodiment, the generated power target value setting means is configured to reduce the target value of generated power to be smaller than the minimum values Pmin1 and Pmin2 based on the minimum values Pmin1 and Pmin2 of demand power within the evaluation time. By setting P0, it is possible to more effectively achieve the reduction in the generation of surplus power and the suppression of the decrease in power generation efficiency by mitigating fluctuations in the generated power.
Further, according to the embodiment, the generated power target value setting means sets the generated power target value P0 to a value that is smaller than the minimum values Pmin1 and Pmin2 of the demand power within the evaluation time by predetermined deviations dP11 and dP12. By setting this, it is possible to more effectively achieve the reduction in the generation of surplus power and the suppression of the reduction in power generation efficiency due to the mitigation of fluctuations in generated power.

In the present embodiment, the target value P0 of the generated power is set to a value that is smaller than the minimum values Pmin1 and Pmin2 of the demand power within the evaluation time by predetermined deviations dP11 and dP12. The values Pmin1 and Pmin2 may be set, or may be set to a value larger than the minimum values Pmin1 and Pmin2 by a predetermined deviation.
Further, according to the embodiment, the control device 30 further sets the target value P0 of the generated power when the target value P0 of the generated power is larger than the demand power P in preference to the generated power target value setting means. By having the generated power target value priority setting means (S10) that is set to be smaller than the demand power P, when the demand power P decreases rapidly, the target value P0 of the generated power is immediately set to be less than the demand power P. By setting it to be small, the generation of surplus power can be reduced.

  Further, the generated power target value priority setting means (S10) makes the generated power target value P0 smaller than the demand power P by a predetermined deviation dP3 when the generated power target value P0 is larger than the demand power P. By setting to, generation of surplus power can be more reliably reduced. However, the deviation dP3 needs to be smaller than a predetermined value dP1 for determining the demand power increase state.

  Although the embodiments of the present invention have been described above with reference to the drawings, the illustrated embodiments are merely illustrative of the present invention, and the present invention is not limited to those shown directly by the described embodiments. It goes without saying that various modifications and changes made by those skilled in the art are included within the scope of the claims.

1 System housing 2 Hydrogen production equipment (reformer)
3 Fuel cell (stack)
4 Power conditioner (inverter)
DESCRIPTION OF SYMBOLS 5 Heat exchanger 6 Combustor 7 Surplus electric power heater 8 Cooling water circulation path 9 Water tank 10 Water pump 11 Cooler 12 Heat recovery path 13 Control device 14 Measuring instrument 15 Measuring instrument 16 Measuring instrument 17 Fuel supply control means 18 Air supply control means

Claims (7)

A fuel cell system comprising a fuel cell for power generation and a control device for controlling the power generated by the fuel cell,
The controller is
Generated power target value setting means for setting a target value of the generated power of the fuel cell based on the minimum value of the demand power within the evaluation time for each predetermined evaluation time, and according to the target value of the generated power , Configured to control the power generated by the fuel cell,
The control device further includes:
The evaluation time is set based on the relationship between the demand power and the target value of the generated power, and the evaluation time is shortened in the demand power increasing state where the demand power exceeds the target value of the generated power by a predetermined value or more. A fuel cell system comprising time varying means.   2. The fuel according to claim 1, wherein the generated power target value setting means sets the target value of the generated power to be smaller than the minimum value based on the minimum value of the demand power within the evaluation time. Battery system.   3. The fuel cell according to claim 2, wherein the generated power target value setting means sets the generated power target value to a value smaller than a minimum value of demand power within an evaluation time by a predetermined deviation. system. The control device further includes:
Prior to the generated power target value setting means, when the generated power target value is larger than the demand power, the generated power target value priority setting means for setting the generated power target value to be smaller than the demand power is provided. The fuel cell system according to any one of claims 1 to 3, wherein: The generated power target value priority setting means sets the generated power target value to be smaller than the demand power by a predetermined deviation when the generated power target value is larger than the demand power,
The fuel cell system according to claim 4, wherein the deviation is smaller than a predetermined value for determining the demand power increase state. A fuel cell system comprising a fuel cell for power generation and a control device for controlling the power generated by the fuel cell,
The controller is
First generated power target value setting means for setting a target value of generated power of the fuel cell based on a minimum value of demand power within the first evaluation time for each first evaluation time;
In a demand power increasing state in which the demand power exceeds the target value of the generated power, a second evaluation time shorter than the first evaluation time has elapsed instead of the first generated power target value setting means. A second generated power target value setting means for setting a target value of the generated power of the fuel cell based on the minimum value of the demand power within the second evaluation time,
Have
A fuel cell system, wherein the generated power of the fuel cell is controlled according to a target value of the generated power. A method for setting a target value of generated power of a fuel cell system,
For each first evaluation time, based on the minimum value of the demand power within the first evaluation time, a target value for the generated power of the fuel cell is set,
In a demand power increase state in which the demand power exceeds the target value of the generated power, when the second evaluation time shorter than the first evaluation time has elapsed, the demand power within the second evaluation time A method for setting a target value of generated power of a fuel cell system, wherein a target value of generated power of the fuel cell is set based on a minimum value.

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