JP5745986B2 - Power supply system, control device, and discharge control method - Google Patents

Description

  The present invention relates to a power feeding system, a control device, and a discharge control method for supplying power to a load by using a fuel cell and a secondary battery together.

  In recent years, fuel cells, which are a type of distributed power source, have been widely used by power consumers. A fuel cell generates power by a chemical reaction between hydrogen extracted from gas and oxygen in the air.

  Since the output power of the fuel cell is variable within the range up to the rated output power (maximum output power), “load following control” is applied to increase or decrease the output power of the fuel cell according to the increase or decrease of the power consumption of the load. It is common to do.

  A fuel cell cannot change the amount of power generation abruptly due to its power generation principle. Therefore, even if load following control is applied to a fuel cell, if the power consumption of the load increases rapidly, the output power of the fuel cell is insufficient with respect to the power consumption of the load (hereinafter referred to as “following delay shortage”). .

  In view of such a situation, a power feeding system has been proposed in which a fuel cell is used in combination with a small battery with a small capacity and the follow-up delay is compensated for by discharging the secondary battery (see, for example, Patent Document 1).

JP-A-7-123609

  However, even if the insufficient follow-up delay is compensated for by the discharge of the secondary battery, if the power consumption of the load exceeds the rated output power of the fuel cell, the output power of the fuel cell is still insufficient relative to the power consumption of the load. (Hereinafter referred to as “the excess and shortage of ratings”).

  Here, although it is possible to make up for the excess and deficiency of excess ratings with the electric power from the commercial power system, there is a problem of an increase in utility costs due to power purchase. Alternatively, consumers who have solar cells in addition to fuel cells can make up for the excess and shortage of ratings by the output power of the solar cells, but at present, the unit price of electricity from solar cells is set high, and the utility costs From the viewpoint of reduction, it is desirable to actively sell the output power of the solar cell.

  Accordingly, the present invention provides a power feeding system, a control device, and a discharge control method that can compensate not only for insufficient follow-up delay but also for insufficient over-rating by a secondary battery for compensating load followability of a more effective fuel cell. The purpose is to provide.

  In order to solve the above-described problems, the present invention has the following features.

  The power supply system according to the present invention is characterized by a power supply including a fuel cell (for example, SOFC110) to which load following control is applied and a secondary battery (secondary battery 115) for supplementing the load followability of the fuel cell. A control unit (control) that performs first discharge control for discharging the secondary battery so as to compensate for a shortage of output power of the fuel cell when the power consumption of a load (load 400) increases. Unit 143), and the control unit performs the first discharge control when the power consumption of the load increases and the power consumption exceeds the rated output power of the fuel cell. The gist is to perform second discharge control for further discharging at least a part of the charged amount of the secondary battery.

  In such a power supply system, when the power consumption of the load increases and the power consumption exceeds the rated output power of the fuel cell, after performing the first discharge control to compensate for the insufficient follow-up delay, Second discharge control is performed to compensate for the excess or deficiency of the rating. Thereby, the secondary battery for supplementing the load followability of the fuel cell can compensate for not only the follow-up delay deficiency but also the over-rated deficiency.

  Further, in the case of having a solar cell in addition to the fuel cell, the output power of the solar cell that is consumed by the load can be sent to the power sale, so that the amount of power sale can be increased.

  According to another feature of the power supply system according to the present invention, the control unit performs the first discharge control when the power consumption of the load increases and the power consumption exceeds the rated output power. The amount of electricity stored in the secondary battery can be determined from the amount of discharge of the secondary battery that is predicted to be necessary when the first discharge control is performed next time until the first discharge control is performed next time. The second discharge control is performed when the amount of charge of the secondary battery predicted to be larger than the reduced amount.

  According to another feature of the power feeding system according to the present invention, the control unit is configured to perform the first discharge even when the power consumption of the load increases and the power consumption exceeds the rated output power. The first discharge control is performed next time based on the amount of storage of the secondary battery that is predicted to be necessary when the first discharge control is performed next time. The second discharge control is not performed when the amount of charge of the secondary battery predicted to be possible is less than the amount reduced.

  According to another feature of the power supply system according to the present invention, the control unit is configured to increase the power consumption of the load and the power consumption exceeds the rated output power, and the excess period has elapsed. The second discharge control is performed when it is predicted that the secondary battery can be charged before the first discharge control is performed next time.

  According to another feature of the power feeding system according to the present invention, the control unit has a period of excess even when the power consumption of the load increases and the power consumption exceeds the rated output power. When it is predicted that charging of the secondary battery is impossible before the first discharge control is performed after the elapse of time, the second discharge control is not performed.

  According to another feature of the power supply system according to the present invention, the power supply system further includes another power generation device (for example, PV210) that is allowed to sell output power to the commercial power system (commercial power system 10), and the control unit Makes it possible to perform the second discharge control when the other power generation device is performing an interconnection operation with the commercial power system.

  According to another feature of the power feeding system according to the present invention, the control unit is configured to generate the other power generation device even when the power consumption of the load increases and the power consumption exceeds the rated output power. When performing independent operation, the second discharge control is not performed.

  According to another feature of the power supply system according to the present invention, the control unit determines whether or not to perform the second discharge control at a timing when the power consumption of the load reaches the rated output power.

  According to another characteristic of the power supply system according to the present invention, the control unit periodically determines whether or not the second discharge control should be continued after starting the second discharge control. .

  A characteristic of the control device according to the present invention is a power supply including a fuel cell (for example, SOFC 110) to which load following control is applied, and a secondary battery (secondary battery 115) for supplementing the load following property of the fuel cell. A control device (e.g., SOFC control device 140) used in the system, wherein when the power consumption of a load increases, the first discharges the secondary battery so as to compensate for the shortage of the output power of the fuel cell. A control unit (control unit 143) that performs discharge control, wherein the control unit increases the power consumption of the load and the power consumption exceeds the rated output power of the fuel cell; The gist is to perform the second discharge control for further discharging at least a part of the charged amount of the secondary battery after performing the discharge control.

  A feature of the discharge control method according to the present invention is a discharge control method used in a power supply system including a fuel cell to which load following control is applied and a secondary battery for supplementing load followability of the fuel cell. When the load power consumption increases, a step of performing a first discharge control for discharging the secondary battery so as to compensate for the shortage of the output power of the fuel cell (for example, step S105), When the power consumption increases and the power consumption exceeds the rated output power of the fuel cell, after performing the first discharge control, at least a part of the charged amount of the secondary battery is further discharged. And a step of performing second discharge control (for example, step S110).

  According to the present invention, there is provided a power feeding system, a control device, and a discharge control method capable of compensating not only for insufficient follow-up delay but also for insufficient excess of rating by a secondary battery for supplementing load followability of a more effective fuel cell. Can be provided.

It is a block diagram of the electric power feeding system which concerns on 1st Embodiment-3rd Embodiment of this invention. It is a block diagram of the SOFC control apparatus which concerns on 1st Embodiment-3rd Embodiment of this invention. It is a figure for demonstrating the load following control which concerns on 1st Embodiment-3rd Embodiment of this invention. It is a processing flow figure of load following control concerning a 1st embodiment-a 3rd embodiment of the present invention. It is a figure for demonstrating the 1st discharge control which concerns on 1st Embodiment-3rd Embodiment of this invention. It is a figure for demonstrating the 2nd discharge control which concerns on 1st Embodiment-3rd Embodiment of this invention. It is a processing flow figure of charge / discharge control concerning a 1st embodiment of the present invention. It is a processing flow figure of charge / discharge control concerning a 2nd embodiment of the present invention. It is a processing flow figure of charge / discharge control concerning a 3rd embodiment of the present invention.

  The first to third embodiments of the present invention and other embodiments will be described with reference to the drawings. In the drawings according to the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

[First Embodiment]
(Configuration of power supply system)
FIG. 1 is a block diagram of a power feeding system according to the present embodiment. In FIG. 1, a thick line shows a power line, and a broken line shows a control line. The control line may be configured wirelessly.

  As shown in FIG. 1, the power supply system according to the present embodiment includes a solid oxide fuel cell (SOFC) unit 100, a solar cell (PV) unit 200, a distribution board 300, one or more loads 400, and a house. It has an energy management system (HEMS) 500. The SOFC unit 100, the PV unit 200, the distribution board 300, the load 400, and the HEMS 500 are provided in the customer 1 that receives supply of alternating current (AC) power from the commercial power system 10.

  The SOFC unit 100 includes an SOFC 110, a secondary battery 115, a power conditioner (PCS) 120, and an SOFC control device 140.

  The SOFC 110 is a type of fuel cell, and generates power by a chemical reaction between hydrogen extracted from natural gas or the like and oxygen in the air, and outputs direct current (DC) power to the PCS 120. The power generation amount of the SOFC 110 changes according to the amount of gas and air consumed by the SOFC 110. The amounts of gas and air are controlled by the SOFC controller 140. The SOFC 110 output power is not allowed to be sold to the commercial power system 10.

  The secondary battery 115 has a small size and a small capacity to supplement the load followability of the SOFC 110. The secondary battery 115 is charged with DC power input from the SOFC 110 via the PCS 120. However, when the PCS 120 has not only the DC-AC conversion function but also the AC-DC conversion function, the secondary battery 115 is charged by the output power from the PV unit 200 and / or the power from the commercial power system 10. Also good. The secondary battery 115 outputs DC power to the PCS 120 by discharging.

  The PCS 120 receives the DC power output from the SOFC 110 and the DC power output from the secondary battery 115, converts the input DC power into AC power, and transmits the AC power via the SOFC power line 12 (hereinafter referred to as “SOFC unit”). (Referred to as “output power”) to the distribution board 300.

  The SOFC control device 140 performs communication with the measurement unit 310 provided in the distribution board 300 and communication with the HEMS 500. The SOFC control device 140 controls the SOFC 110, the secondary battery 115, and the PCS 120 based on information from the measurement unit 310 and the HEMS 500.

  The SOFC control device 140 performs load follow-up control that increases or decreases the output power of the SOFC 110 in accordance with the increase or decrease of the power consumption of the load 400. In addition, the SOFC control device 140 performs charge / discharge control of the secondary battery 115. Details of the load following control and charge / discharge control will be described later.

  The PV unit 200 has a PV 210 and a PCS 220.

  The PV 210 receives sunlight to generate power and output DC power. The amount of power generated by the PV 210 changes according to the amount of solar radiation irradiated on the PV 210.

  The PCS 220 receives DC power output from the PV 210, converts the input DC power into AC power, and distributes AC power (hereinafter referred to as “PV unit output power”) via the PV power line 13. It outputs to the board 300. If the PV 210 detects a power outage or an unstable state of the commercial power system 10 while the PV 210 is performing an interconnection operation with the commercial power system 10, the PCS 220 disconnects the PV 210 from the commercial power system 10 and performs independent operation. .

  The distribution board 300 receives power (hereinafter referred to as “purchased power”) from the commercial power system 10 through the system power line 11, and the SOFC unit output power from the SOFC unit 100 through the SOFC power line 12. The PV unit output power is input from the PV unit 200 through the PV power line 13.

  In the case where the power consumption of the load 400 can be covered only by the SOFC unit output power, the distribution board 300 does not purchase power from the commercial power system 10 and sells all PV unit output power to the commercial power system 10. (Reverse current). When the power consumption of the load 400 cannot be covered only by the SOFC unit output power, the distribution board 300 compensates the shortage with the PV unit output power. If the power is still insufficient, the distribution board 300 purchases power from the commercial power system 10. I do.

  The distribution board 300 includes a measurement unit 310 that periodically measures the power consumption, power sales power, and power purchase power of the load 400. The measurement part 310 notifies a measured value to the SOFC control apparatus 140 and HEMS500 regularly.

  The load 400 receives AC power from the distribution board 300 via the load power line 14, and operates by consuming the input AC power. The load 400 is, for example, a home appliance such as an illumination, an air conditioner, a refrigerator, or a television.

  The HEMS 500 is for performing power management in the customer 1. The HEMS 500 manages and displays the power consumption, power sales power, and power purchase power of the load 400, and performs control for power saving on the load 400.

  Next, the configuration of the SOFC control device 140 will be described. FIG. 2 is a block diagram of the SOFC control device 140.

  As illustrated in FIG. 2, the SOFC control device 140 includes a communication unit 141, a storage unit 142, and a control unit 143.

  The communication unit 141 communicates with the SOFC 110, the secondary battery 115, the PCS 120, the measurement unit 310, and the HEMS 500. The communication unit 141 receives information on the power consumption of the load 400 at the current time from the measurement unit 310. Further, the communication unit 141 receives information on the output power of the SOFC 110 at the current time from the SOFC 110 or the PCS 120. The communication unit 141 receives information on the storage amount of the secondary battery 115 at the current time from the secondary battery 115 or the PCS 120.

  The storage unit 142 is configured by a memory or the like, and stores various information used for control in the control unit 143. The storage unit 142 includes information on a transition pattern of power consumption of the load 400 (hereinafter, “power consumption transition pattern”), information on the rated output power of the SOFC 110 (hereinafter, “SOFC rated output power”), and load tracking of the SOFC 110. Information on performance (hereinafter referred to as “SOFC load following performance”) is stored in advance. Information on the power consumption transition pattern is created based on learning for one day or more. The information on the power consumption transition pattern may be created by the control unit 143 or by the HEMS 500.

  The control unit 143 includes a processor or the like, and controls various functions of the SOFC control device 140. The control unit 143 performs load follow-up control and charge / discharge control.

  The control unit 143 performs first discharge control for discharging the secondary battery 115 so as to compensate for the shortage of the output power of the SOFC 110 when the power consumption of the load 400 increases. In addition, when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power, the control unit 143 performs the first discharge control and then at least the amount of power stored in the secondary battery 115 Second discharge control for further discharging a part is performed.

(Operation of SOFC controller)
Next, the operation of the SOFC control device 140 will be described in the order of load following control and charge / discharge control.

(1) Load following control FIG. 3 is a diagram for explaining load following control. 3 (and FIGS. 5 and 6), the solid line indicates the power consumption of the load 400, the broken line indicates the output power of the SOFC 110, and the thick line indicates the SOFC rated output power.

  As shown in FIG. 3, at time t1, the power consumption of the load 400 starts to increase. Based on the power consumption information received by the communication unit 141 from the measurement unit 310, the control unit 143 sets the target output power of the SOFC 110 (hereinafter referred to as “SOFC target output power”) so as to follow the increase in power consumption of the load 400. To increase. Since the output power of the SOFC 110 does not immediately reach the SOFC target output power, the output power of the SOFC 110 reaches the SOFC target output power at time t2.

  Once the power consumption of the load 400 decreases within the period from time t2 to time t3, the control unit 143 decreases the SOFC target output power so as to follow the decrease in power consumption of the load 400.

  The power consumption of the load 400 starts increasing at time t3, the power consumption of the load 400 exceeds the SOFC rated output power within the period from time t3 to t4, and the excess state continues until time t5. The control unit 143 increases the SOFC target output power so as to follow the increase in power consumption of the load 400, but after the power consumption of the load 400 exceeds the SOFC rated output power, the SOFC target output power is converted to the SOFC rated output. Set to a value equal to power.

  When the power consumption of the load 400 decreases to less than the SOFC rated output power during the period from time t5 to time t6, the control unit 143 decreases the SOFC target output power so as to follow the decrease in the power consumption of the load 400.

  The power consumption of the load 400 starts increasing at time t6, the power consumption of the load 400 exceeds the SOFC rated output power within the period from time t6 to t7, and the excess state continues until time t8. The control unit 143 increases the SOFC target output power so as to follow the increase in power consumption of the load 400, but after the power consumption of the load 400 exceeds the SOFC rated output power, the SOFC target output power is converted to the SOFC rated output. Set to a value equal to power.

  When the power consumption of the load 400 significantly decreases to less than the SOFC rated output power during the period from time t8 to t9, the control unit 143 decreases the SOFC target output power so as to follow the decrease in the power consumption of the load 400.

  When the power consumption of the load 400 increases during the period from time t9 to t10, the control unit 143 increases the SOFC target output power so as to follow the increase in the power consumption of the load 400. Since the output power of the SOFC 110 does not immediately reach the target output power, the output power of the SOFC 110 reaches the target output power at time t10.

  FIG. 4 is a processing flowchart of load following control.

  As illustrated in FIG. 4, in step S <b> 10, the control unit 143 acquires information on the power consumption of the load 400 at the current time from the communication unit 141 and acquires information on the SOFC rated output power from the storage unit 142. Thereafter, the process proceeds to step S20.

  In step S20, the control unit 143 confirms whether or not the current power consumption of the load 400 is equal to or higher than the SOFC rated output power, based on the information acquired in step S10. If the current power consumption of the load 400 is less than the SOFC rated output power (step S20; NO), the process proceeds to step S30. When the current power consumption of the load 400 is equal to or higher than the SOFC rated output power (step S20; YES), the process proceeds to step S40.

  In step S <b> 30, the control unit 143 sets the SOFC target output power to a value equal to the power consumption of the load 400 and causes the storage unit 142 to store the target output power. Thereafter, the process proceeds to step S50.

  On the other hand, in step S40, the control unit 143 sets the SOFC target output power to a value equal to the SOFC rated output power, and causes the storage unit 142 to store the target output power. Thereafter, the process proceeds to step S50.

  In step S50, the control unit 143 adjusts the amounts of gas and air in the SOFC 110 so that the output power of the SOFC 110 becomes the target output power set in step S30 or step S40. Thereafter, the process returns to step S10.

(2) Charge / Discharge Control FIG. 5 is a diagram for explaining the first discharge control. Based on the information on the current SOFC target output power and the information on the output power of the SOFC 110 at the current time, the control unit 143 has a shortage of the current output power of the SOFC 110 with respect to the current SOFC target output power (that is, , Shortage of follow-up delay). And the control part 143 controls the secondary battery 115 via the communication part 141 so that the electric power equivalent to the said follow-up delay shortage may be discharged. In FIG. 5, hatched portions correspond to insufficient tracking delay.

  As shown in FIG. 5, the control unit 143 performs control so as to discharge electric power corresponding to insufficient follow-up delay in each period of time t1 to t2, time t3 to t4, time t6 to t7, and time t9 to t10. To do.

  FIG. 6 is a diagram for explaining the second discharge control.

  As shown in FIG. 6, the power consumption of the load 400 exceeds the SOFC rated output power during the period from the middle of time t3 to t4 to the time t5, and the period of time t7 to t8. Thus, the output power of the SOFC 110 is deficient (that is, the excess of the rating is insufficient). In the first discharge control described above, the excess and deficiency cannot be compensated for, so the purchased power from the commercial power system 10 and / or the PV unit output power is consumed by the load 400.

  Therefore, the control unit 143 performs the second discharge control for compensating for the excess and deficiency of the rating within a range that does not hinder the first discharge control. Specifically, the control unit 143 performs the first discharge control when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power, and then stores the amount of power stored in the secondary battery 115. Second discharge control for further discharging at least a part of the second discharge control is performed.

  In this embodiment, when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power, the control unit 143 uses the power consumption transition pattern and the SOFC load following performance stored in the storage unit 142. The amount of discharge of the secondary battery 115 that is predicted to be necessary when the first discharge control is performed next time, and the secondary battery 115 that is predicted to be possible before the first discharge control is performed based on the information of Obtain (calculate) the charge amount.

  Then, the control unit 143 performs the first discharge control on the next time based on the discharge amount of the secondary battery 115 that is predicted that the current storage amount of the secondary battery 115 is necessary when the first discharge control is performed next time. The second discharge control is performed when the amount of charge of the secondary battery 115 that is predicted to be possible is larger than the amount obtained by subtracting the amount. On the other hand, the amount of power stored in the secondary battery 115 at the present time is estimated from the amount of discharge of the secondary battery 115 predicted to be necessary when the first discharge control is performed next time until the first discharge control is performed next time. If the amount of charge of the secondary battery 115 predicted to be possible is less than the amount obtained by reducing the charge amount, the control unit 143 does not perform the second discharge control. The control unit 143 makes such a determination at a timing when the power consumption of the load 400 exceeds the SOFC rated output power. Further, such a determination is periodically executed even during execution of the second discharge control.

  In FIG. 6, the control unit 143 performs the second discharge control in the overrated period from time t7 to t8 without performing the second discharge control in the overrated period from time t3 to t4 to time t5. Do.

  FIG. 7 is a process flow diagram of charge / discharge control according to the present embodiment.

  As illustrated in FIG. 7, in step S <b> 100, the control unit 143 acquires information on the power consumption of the load 400 at the current time from the communication unit 141 and acquires information on the SOFC rated output power from the storage unit 142. Thereafter, the process proceeds to step S101.

  In step S101, the control unit 143 confirms whether or not the current power consumption of the load 400 is equal to or higher than the SOFC rated output power, based on the information acquired in step S100. If the current power consumption of the load 400 is less than the SOFC rated output power (step S101; NO), the process proceeds to step S102. If the current power consumption of the load 400 is equal to or higher than the SOFC rated output power (step S101; YES), the process proceeds to step S106.

  In step S102, the control unit 143 acquires information on the output power of the SOFC 110 at the current time from the communication unit 141, and acquires information on the current SOFC target output power from the storage unit 142. Then, the control unit 143 confirms whether or not the current output power of the SOFC 110 is equal to the current SOFC target output power. If the current output power of the SOFC 110 is equal to the current SOFC target output power (step S102; YES), the process returns to step S100, and the current output power of the SOFC 110 is not equal to the current SOFC target output power. If so (step S102; NO), the process proceeds to step S103.

  In step S103, the control unit 143 determines whether or not the secondary battery 115 can be charged. For example, if the current storage amount of the secondary battery 115 is smaller than the maximum storage amount, it is determined that the secondary battery 115 can be charged. Further, when the output power from the PV unit 200 and / or the power from the commercial power system 10 can be used for charging, it may be determined that the secondary battery 115 can be charged. When it is determined that the secondary battery 115 can be charged (step S103; YES), the process proceeds to step S106, and when it is determined that the secondary battery 115 cannot be charged (step S103; NO), the process Advances to step S104.

  In step S104, the control unit 143 confirms whether or not the current output power of the SOFC 110 is smaller than the current SOFC target output power. If the current output power of the SOFC 110 is smaller than the current SOFC target output power (step S104; YES), the process proceeds to step S105. When the current output power of the SOFC 110 is larger than the current SOFC target output power (step S104; NO), the process returns to step S100. The surplus power due to such a follow-up delay may be used for charging the secondary battery 115.

  In step S105, the control unit 143 performs the first discharge control described above. Specifically, the control unit 143 discharges the power of the shortage of the output power of the SOFC 110 at the current time relative to the current SOFC target output power (that is, the current SOFC target output power−the current output power of the SOFC 110). Control to do. Thereafter, the process returns to step S100.

  On the other hand, in step S <b> 106, the control unit 143 is based on the current storage amount of the secondary battery 115 and the remaining output capacity of the SOFC 110 (that is, SOFC rated output power−current output power of the SOFC 110). Thus, the SOFC target output power is corrected upward with the SOFC rated output power as the upper limit. Thereby, the surplus of the output power of the SOFC 110 is increased. Thereafter, the process proceeds to step S107.

  In step S107, the control unit 143 performs charge control. Specifically, the control unit 143 controls the secondary battery 115 to charge the surplus output power of the SOFC 110. Thereafter, the process returns to step S100.

  On the other hand, in step S108, the control unit 143 acquires the power consumption transition pattern and the SOFC load tracking performance from the storage unit 142, and acquires information on the current power storage amount from the communication unit 141. Then, the control unit 143 performs the first discharge control and the discharge amount of the secondary battery 115 predicted to be necessary when the first discharge control is performed next time based on the power consumption transition pattern and the SOFC load following performance. The amount of charge of the secondary battery 115 predicted to be possible until the next time is acquired (calculated). Thereafter, the process proceeds to step S109.

  In step S <b> 109, the control unit 143 determines the first discharge control based on the discharge amount of the secondary battery 115 that is predicted that the current storage amount of the secondary battery 115 is necessary when the first discharge control is performed next time. It is confirmed whether or not it is larger than the amount obtained by reducing the charge amount of the secondary battery 115 predicted to be possible until the next time. If it is large (step S109; YES), the process proceeds to step S108, and if it is small (step S109; NO), the process returns to step S100.

  In step S110, the control unit 143 performs the second discharge control described above. Specifically, the control unit 143 has a power shortage of the current output power of the SOFC 110 with respect to the current power consumption of the load 400 (that is, the current power consumption of the load 400-the current output power of the SOFC 110). Control to discharge. Thereafter, the process returns to step S100.

(Summary of the first embodiment)
As described above, the power supply system according to the present embodiment includes the SOFC 110 to which load following control is applied, and the secondary battery 115 for supplementing the load following performance of the SOFC 110. The control unit 143 performs first discharge control for discharging the secondary battery 115 so as to compensate for the shortage of the output power of the SOFC 110 when the power consumption of the load 400 increases. When the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power, the control unit 143 performs at least a part of the charged amount of the secondary battery 115 after performing the first discharge control. The second discharge control for further discharging the battery is performed.

  In this way, when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power, after performing the first discharge control to compensate for the follow-up delay shortage, the overrated shortage Second discharge control is performed to compensate for this. As a result, the secondary battery 115 for supplementing the load followability of the SOFC 110 can compensate not only the insufficient follow-up delay but also the excess over-rated amount. Further, since the output power of the PV 210 that is consumed by the load 400 can be sent to the power sale, the amount of power sale can be increased.

  In the present embodiment, the control unit 143 increases the power consumption of the load 400 and the power consumption exceeds the SOFC rated output power, and the current storage amount of the secondary battery 115 is the first discharge control. When the amount of discharge of the secondary battery 115 predicted to be necessary next time is larger than the amount obtained by subtracting the amount of charge of the secondary battery 115 predicted to be possible before the first discharge control is performed next time Second discharge control is performed. As a result, the second discharge control can be performed within a range in which the next first discharge control is regarded as having no problem.

  In the present embodiment, the control unit 143 determines that the power storage amount of the secondary battery 115 at the current time is the first even when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power. The amount of discharge of the secondary battery 115 predicted to be necessary when the discharge control is performed next time is less than the amount obtained by subtracting the charge amount of the secondary battery 115 predicted to be possible until the first discharge control is performed next time. When the number is small, the second discharge control is not performed. This can prevent the next first discharge control from being hindered.

  In the present embodiment, the control unit 143 determines whether or not to perform the second discharge control at a timing when the power consumption of the load 400 reaches the SOFC rated output power. Thereby, it is possible to determine whether or not to perform the second discharge control in consideration of the current situation (such as the amount of power stored in the secondary battery 115).

  In the present embodiment, after starting the second discharge control, the control unit 143 periodically determines whether or not to continue the second discharge control. Thus, it is possible to determine whether or not to perform the second discharge control in consideration of the situation after the second discharge control is started (such as the amount of power stored in the secondary battery 115).

[Second Embodiment]
Hereinafter, the difference between the second embodiment and the first embodiment will be mainly described. This embodiment is different from the first embodiment in part of charge / discharge control.

  In the present embodiment, the control unit 143 performs the first discharge control next time after the excess period elapses when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power. When it is predicted that the secondary battery 115 can be charged by the time, the second discharge control is performed. On the other hand, even when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power, the second period after the excess period has elapsed until the first discharge control is performed next time. When it is predicted that the secondary battery 115 cannot be charged, the control unit 143 does not perform the second discharge control.

  FIG. 8 is a process flow diagram of charge / discharge control according to the present embodiment. In FIG. 8, steps S200 to S207 are the same as steps S100 to S107 described in the first embodiment, and therefore the processing after step S208 will be described.

  As illustrated in FIG. 8, in step S <b> 208, the control unit 143 acquires information on the power consumption transition pattern from the storage unit 142 and acquires information on the current power storage amount from the communication unit 141. Then, based on the power consumption transition pattern, the control unit 143 acquires (calculates) a time predicted to perform the next first discharge control and a time predicted to perform the next charge control. To do. Thereafter, the process proceeds to step S209.

  In step S209, the control unit 143 checks whether or not the time predicted to perform the next charge control is ahead of the time predicted to perform the next first discharge control. If it is earlier (step S209; YES), the process proceeds to step S210. If it is later (step S209; NO), the process returns to step S200.

  In step S210, the control unit 143 performs the second discharge control described above. Specifically, the control unit 143 has a power shortage of the current output power of the SOFC 110 with respect to the current power consumption of the load 400 (that is, the current power consumption of the load 400-the current output power of the SOFC 110). Control to discharge. Thereafter, the process returns to step S200.

  As described above, in the present embodiment, the control unit 143 increases the power consumption of the load 400 and the power consumption exceeds the SOFC rated output power. When it is predicted that the secondary battery 115 can be charged before the next discharge control is performed, the second discharge control is performed. Thus, the second discharge control can be performed while reducing the possibility of hindering the next first discharge control.

  In the present embodiment, the control unit 143 performs the first discharge control after the excess period has elapsed even when the power consumption of the load 400 increases and the power consumption exceeds the SOFC rated output power. If it is predicted that charging of the secondary battery 115 is not possible until the next time is performed, the second discharge control is not performed. This can prevent the next first discharge control from being hindered.

[Third Embodiment]
Hereinafter, the difference between the third embodiment and the first embodiment will be mainly described. This embodiment is different from the first embodiment in part of charge / discharge control.

  In the present embodiment, the control unit 143 makes it possible to perform the second discharge control when the PV 210 is performing an interconnection operation with the commercial power system 10. On the other hand, when the PV 210 is performing a self-sustaining operation, the second discharge control is not performed.

  FIG. 9 is a process flow diagram of charge / discharge control according to the present embodiment. Since Steps S300 to S307 are the same as Steps S100 to S107 described in the first embodiment, the processes after Step S308 will be described.

  As shown in FIG. 9, in step S <b> 308, the control unit 143 determines whether or not the PV 210 is performing an interconnection operation with the commercial power system 10 based on information obtained from the measurement unit 310 or information obtained from the HEMS 500. Confirm. When the PV 210 is performing an interconnection operation with the commercial power system 10 (step S308; YES), the process proceeds to step S309, and when the PV 210 is performing a self-sustaining operation (step S308; NO), the process is step S300. Return to.

  In step S309, the control unit 143 acquires the power consumption transition pattern and the SOFC load following performance from the storage unit 142, and acquires information on the current power storage amount from the communication unit 141. Then, the control unit 143 performs the first discharge control and the discharge amount of the secondary battery 115 predicted to be necessary when the first discharge control is performed next time based on the power consumption transition pattern and the SOFC load following performance. The amount of charge of the secondary battery 115 predicted to be possible until the next time is acquired (calculated). Thereafter, the process proceeds to step S310.

  In step S <b> 310, the control unit 143 determines the first discharge control from the discharge amount of the secondary battery 115 that is predicted that the current storage amount of the secondary battery 115 is necessary when the first discharge control is performed next time. It is confirmed whether or not it is larger than the amount obtained by reducing the charge amount of the secondary battery 115 predicted to be possible until the next time. If it is large (step S310; YES), the process proceeds to step S311. If it is small (step S310; NO), the process returns to step S300.

  In step S311, the control unit 143 performs the second discharge control described above. Specifically, the control unit 143 has a power shortage of the current output power of the SOFC 110 with respect to the current power consumption of the load 400 (that is, the current power consumption of the load 400-the current output power of the SOFC 110). Control to discharge. Thereafter, the process returns to step S300.

  As described above, in the present embodiment, the second discharge control can be performed when the PV 210 is performing an interconnection operation with the commercial power system 10. As described above, when the effect of pushing up the power sale amount can be expected, the second discharge control can be performed, and the amount of power sale can be increased by positively compensating for the excess of the rated excess.

  In the present embodiment, the control unit 143 increases the power consumption of the load 400 so that the second power is output when the PV 210 is performing the autonomous operation even when the power consumption exceeds the SOFC rated output power. The discharge control is not performed. As described above, when the power sales amount push-up effect cannot be expected, the second discharge control is not performed, so that the follow-up delay shortage can be more reliably compensated.

[Other Embodiments]
As described above, the present invention has been described according to each embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, also in the second embodiment described above, a determination as to whether the PV 210 is performing a grid-connected operation may be added as in the third embodiment.

  Moreover, in each embodiment mentioned above, although the consumer 1 which has the PV unit 200 was demonstrated, it replaced with the PV unit 200 and you may use the other distributed power supply determined that output power can be sold. . In the first embodiment and the second embodiment, the PV unit 200 may not necessarily be provided.

  In each of the above-described embodiments, an example in which the SOFC control device 140 performs processing related to charge / discharge control of the secondary battery 115 has been described. However, the HEMS 500 may perform processing related to charge / discharge control of the secondary battery 115, and the HEMS 500 may control charge / discharge of the secondary battery 115 via the SOFC control device 140. In this case, for example, the HEMS 500 determines a period during which the second discharge control is possible and notifies the SOFC control device 140 of the result. The SOFC control device 140 performs the second discharge control in the period in which the second discharge control notified from the HEMS 500 is possible.

  In each of the above-described embodiments, an example in which the load tracking control is performed based on the power consumption information of the load 400 has been described. However, the load tracking control may be performed based on the purchased power information. The purchased power reflects the power consumption of the load 400. For example, the load follow-up control can be realized by setting the SOFC target output power so that the purchased power becomes zero.

  The SOFC unit 100 may be provided side by side with a hot water storage unit that stores hot water obtained by collecting exhaust heat generated during power generation. Hot water in the hot water storage unit can be used for hot water supply in the customer 1. Furthermore, the SOFC unit 100 is not limited to being configured in a single casing, and may be configured in a plurality of casings.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein.

  DESCRIPTION OF SYMBOLS 1 ... Consumer, 10 ... Commercial power system, 11 ... System power line, 12 ... SOFC power line, 13 ... PV power line, 14 ... Load power line, 100 ... SOFC unit, 110 ... SOFC, 115 ... Secondary battery, 120 ... PCS, 140 ... SOFC control device, 141 ... communication unit, 142 ... storage unit, 143 ... control unit, 200 ... PV unit, 210 ... PV, 220 ... PCS, 300 ... distribution panel, 310 ... measurement unit, 400 ... Load, 500 ... HEMS

Claims (12)

A power supply system having a fuel cell to which load following control is applied, and a secondary battery for supplementing the load following property of the fuel cell,
A control unit that performs first discharge control for discharging the secondary battery so as to compensate for a shortage of output power of the fuel cell when the power consumption of the load increases;
The control unit is a case where the power consumption of the load is increased and the power consumption exceeds the rated output power of the fuel cell , and the secondary after performing the first discharge control. The secondary storage capacity of the battery is predicted to be possible before the first discharge control is performed next time, based on the discharge amount of the secondary battery that is predicted to be required when the first discharge control is performed next time. A power supply system that performs second discharge control for further discharging at least a part of the charged amount of the secondary battery when the amount of charge of the battery is larger than the reduced amount .   A power supply system having a fuel cell to which load following control is applied, and a secondary battery for supplementing the load following property of the fuel cell,
  A control unit that performs first discharge control for discharging the secondary battery so as to compensate for a shortage of output power of the fuel cell when the power consumption of the load increases;
  The control unit is a case where the power consumption of the load increases and the power consumption exceeds the rated output power of the fuel cell, and the first discharge control is performed after the excess period has elapsed. When it is predicted that the secondary battery can be charged until the next time is performed, the first discharge control is performed, and then at least a part of the charged amount of the secondary battery is further discharged. 2 discharge control
A power supply system characterized by that. The control unit is configured such that, even when the power consumption of the load increases and the power consumption exceeds the rated output power, the storage amount of the secondary battery after performing the first discharge control However, the amount of charge of the secondary battery that is predicted to be possible before the first discharge control is performed next time from the amount of discharge of the secondary battery that is predicted to be necessary when the first discharge control is performed next time. If less than the amount obtained by subtracting the power supply system according to claim 1, characterized in that does not perform the second discharge control. Even if the power consumption of the load increases and the power consumption exceeds the rated output power, the control unit continues until the first discharge control is performed next time after the excess period has elapsed. power feeding system according to claim 2 wherein when the charging of the secondary battery is expected to be impossible, which is characterized not to perform the second discharge control to. It further has another power generation device that is allowed to sell the output power to the commercial power system,
Wherein, when the other of the power generation device is performing interconnected operation with the commercial power system, from claim 1, characterized in that makes it possible to perform the second discharge control 4 The power feeding system according to any one of the above. When the other power generation device is performing a self-sustained operation, the control unit is configured to perform the second operation even when the power consumption of the load increases and the power consumption exceeds the rated output power. The power feeding system according to claim 5 , wherein no discharge control is performed. Wherein, at the timing when the power consumption of the load reaches the rated output power, any one of claims 1 to 6, characterized in that the determination whether or not to perform the second discharge control The power feeding system described in 1. Wherein the control unit, after starting the second discharge control, periodically, any one of claims 1 to 7, characterized in that the determination whether or not to continue the second discharge control The power feeding system described in the section. A control device used in a power supply system having a fuel cell to which load following control is applied, and a secondary battery for supplementing the load following property of the fuel cell,
A control unit that performs first discharge control for discharging the secondary battery so as to compensate for a shortage of output power of the fuel cell when the power consumption of the load increases;
The control unit is a case where the power consumption of the load is increased and the power consumption exceeds the rated output power of the fuel cell , and the secondary after performing the first discharge control. The secondary storage capacity of the battery is predicted to be possible before the first discharge control is performed next time, based on the discharge amount of the secondary battery that is predicted to be required when the first discharge control is performed next time. A control device for performing second discharge control for further discharging at least a part of the charged amount of the secondary battery when the amount of charge of the battery is larger than the reduced amount .   A control device used in a power supply system having a fuel cell to which load following control is applied, and a secondary battery for supplementing the load following property of the fuel cell,
  A control unit that performs first discharge control for discharging the secondary battery so as to compensate for a shortage of output power of the fuel cell when the power consumption of the load increases;
  The control unit is a case where the power consumption of the load increases and the power consumption exceeds the rated output power of the fuel cell, and the first discharge control is performed after the excess period has elapsed. When it is predicted that the secondary battery can be charged until the next time is performed, the first discharge control is performed, and then at least a part of the charged amount of the secondary battery is further discharged. 2 discharge control
A control device characterized by that. A discharge control method used in a power supply system having a fuel cell to which load following control is applied, and a secondary battery for supplementing load followability of the fuel cell,
Performing first discharge control for discharging the secondary battery so as to compensate for a shortage of output power of the fuel cell when the power consumption of the load increases;
The amount of power stored in the secondary battery when the power consumption of the load increases and the power consumption exceeds the rated output power of the fuel cell , and the first discharge control is performed. From the amount of discharge of the secondary battery that is predicted to be necessary when the first discharge control is performed next time, the amount of charge of the secondary battery that is predicted to be possible before the first discharge control is performed next time Performing a second discharge control for further discharging at least a part of the charged amount of the secondary battery when the amount is larger than the reduced amount ;
A discharge control method characterized by comprising:   A discharge control method used in a power supply system having a fuel cell to which load following control is applied, and a secondary battery for supplementing load followability of the fuel cell,
  Performing first discharge control for discharging the secondary battery so as to compensate for a shortage of output power of the fuel cell when the power consumption of the load increases;
  When the power consumption of the load increases and the power consumption exceeds the rated output power of the fuel cell, and after the excess period has elapsed, the first discharge control is performed next time. When it is predicted that the secondary battery can be charged, after performing the first discharge control, a second discharge control for further discharging at least a part of the charged amount of the secondary battery is performed. Steps to do,
A discharge control method characterized by comprising:

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