JP2006286450A - Fuel cell system, its control method, and its control device - Google Patents

Fuel cell system, its control method, and its control device Download PDF

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JP2006286450A
JP2006286450A JP2005105929A JP2005105929A JP2006286450A JP 2006286450 A JP2006286450 A JP 2006286450A JP 2005105929 A JP2005105929 A JP 2005105929A JP 2005105929 A JP2005105929 A JP 2005105929A JP 2006286450 A JP2006286450 A JP 2006286450A
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hot water
water supply
fuel cell
means
amount
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JP2005105929A
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Inventor
Yasuyuki Arimitsu
Masahiro Komachiya
Yoshihide Kondo
Kenji Takeda
昌宏 小町谷
保幸 有光
賢治 武田
由英 近藤
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Babcock Hitachi Kk
バブコック日立株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/50Fuel cells

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system highly efficient operation by estimating a heat demand with a low power loss, in a system to supply power and heat output from a fuel cell to each load. <P>SOLUTION: A plurality of temperature detectors 121-123 are vertically disposed with spaces left between them in a hot water storage tank 5 to store warm water heated by heat generation caused by the power generating operation of the fuel cell 1, and an amount of stored heat in the hot water tank 5 is determined by temperatures detected by them. The records of a hot water supply and demand is detected by the reduction of the amount of stored heat, and hot water supply and demand from this time on is estimated to control the operation of the fuel cell 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system that supplies energy to an electrical load and a heat load using a fuel cell, and a control method and apparatus therefor.

  In recent years, the use of fuel cells as an energy source for electric power and heat in houses has been studied. The fuel cell can directly convert chemical energy into electric power, so that excellent conversion efficiency can be obtained. In addition, so-called cogeneration systems are being studied that use heat associated with power generation by fuel cells to increase total energy efficiency. Patent Document 1 discloses a cogeneration system that predicts the demand for electric power and hot water supply, and presets an optimal operation plan to realize power generation and hot water supply.

JP 2004-263622 A (Overall)

  However, when a hot water supply flow rate sensor is used as a hot water supply demand detection means necessary for prediction of hot water supply demand, there is a problem that power loss of the flow rate sensor is large and energy efficiency is deteriorated.

  An object of the present invention is to provide a fuel cell system with high energy efficiency.

  In one aspect of the present invention, the hot water warmed by the heat generated by the fuel cell power generation operation is stored in a hot water storage tank, and the hot water storage tank is based on the outputs of a plurality of temperature detectors for detecting the temperature of the hot water in the hot water storage tank. The amount of stored heat is determined, and the output of the fuel cell is controlled according to the determination result of the stored amount of heat.

  In a preferred embodiment of the present invention, future hot water supply demand is predicted using hot water supply demand information based on the determination of the amount of stored heat, and the output of the fuel cell is controlled according to this prediction.

  According to a preferred embodiment of the present invention, it is possible to detect hot water supply demand with low loss, and to provide highly efficient operation of a fuel cell.

  Other objects and features of the present invention will become apparent from the embodiments described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram showing an outline of a fuel cell system according to an embodiment of the present invention. The configuration of the fuel cell system will be described from the main circuit of power output. First, the electric output terminal of the fuel cell 1 is connected to the DC / DC converter 2 and the output current of the fuel cell 1 is controlled. The output side of the DC / DC converter 2 is connected to a DC capacitor 3 and a DC / AC inverter 4, and the DC output power is converted into AC power. The output of the DC / AC inverter 4 is supplied to a household electric load 25 via a reactor 20 for removing harmonics, a capacitor 21 and a shut-off unit 24. The DC circuit between the DC / DC converter 2 and the DC / AC inverter 4 is connected to the storage battery 44 via the DC / DC converter 45. The DC / DC converter 45 is a bidirectional converter that controls charging / discharging of the storage battery 44. The operation of this fuel cell system is controlled by a control device 29 described later in detail.

  The system output after removing the harmonics connected to the power load 25 via the shut-off means 24 is connected to the commercial power supply 28 via the domestic power receiving board 27.

  The detection of the current / voltage of the electric system will be described. First, the voltage detection means 17 and the current detection means 18 on the connection line between the fuel cell 1 and the DC / DC converter 2 detect the voltage 38 and the current 39 of the fuel cell, respectively. The output current and voltage of the DC / AC inverter 4 are detected as a current detection value 35 and a voltage detection value 36 by the current detection means 22 and the voltage detection means 23, respectively. On the other hand, the current flowing from the commercial power supply 28 via the domestic power receiving panel 27 is detected as the received current detection value 37 by the received current detecting means 26. Furthermore, the current detection means 46 and the voltage detection means 47 on the connection line between the storage battery 44 and the bidirectional DC / DC converter 45 detect a current detection value 48 and a voltage detection value 49, respectively. The charge amount 51 of the storage battery 44 is estimated using the voltage, current integrated value, and temperature of the storage battery. Further, voltage detection means 19 is provided at both ends of the DC capacitor 3 to output a voltage detection value 41.

  The fuel gas 15 generated by the fuel gas production means 14 is controlled to an appropriate flow rate by the fuel gas valve 16 and supplied to the fuel cell 1 as fuel.

  Next, utilization of the thermal energy generated in the fuel cell 1 will be described. First, a circulating water path 7 for cooling the fuel cell 1 is connected. A circulating water path 7 is piped so that water discharged from the circulating water tank 8 passes through the primary side of the heat exchanger 6 after passing through the inside of the fuel cell 1 and returns to the circulating water tank 8. The water treatment device 13 supplies high-purity water to the circulating water path 7.

  There is a hot water storage tank 5 for storing tap water taken from a water intake means 9 such as a domestic water supply, and the water at the bottom of the hot water storage tank 5 passes through the secondary side of the heat exchanger 6 by the circulation pump 31 to the top of the hot water storage tank 5. Circulate. Water is gently circulated between the hot water storage tank 5 and the heat exchanger 6, and due to the temperature difference between the front and rear of the heat exchanger 6, hot water is concentrated from the upper side of the hot water storage tank 5, and cold water is concentrated on the bottom side of the hot water storage tank 5. Can form a layered temperature distribution in the vertical direction with almost no mixing. In addition, a reheating device 10 that warms water from the bottom of the hot water storage tank 5 and supplies it to the top of the hot water storage tank 5 is also piped. Here, hot water is supplied from the top of the hot water storage tank 5 to the mixing valve 55, and at the same time, the same amount of hot water supplied to the mixing valve 55 is supplied from the water intake means 9 to the bottom of the hot water storage tank 5. Therefore, the total amount of water in the hot water storage tank 5 is kept constant (full tank). The mixing valve 55 mixes hot water obtained from the top of the hot water storage tank 5 and cold water obtained from the water intake means 9 based on the mixing valve control command 57. The water output mixed by the mixing valve 55 is supplied on the one hand to the electromagnetic valve 59 and on the other hand to the manual mixing valve 61. The electromagnetic valve 59 is opened / closed by a valve opening / closing command 60. The manual mixing valve 61 may be a mixing valve used by a resident in the home. One or both of the outputs of the manual mixing valve 61 and the electromagnetic valve 59 are supplied to the domestic heat load 11.

  Next, hot water-related sensors will be described.

  The hot water storage tank 5 is provided with a water temperature detection means 12 including a plurality of temperature detectors 121 to 123 to detect a water temperature detection value 30. In the water temperature detectors 121 to 123, for example, thermistors are arranged on the inner surface or outer surface of the hot water storage tank 5 at intervals in the height direction. The outlet temperature of the mixing valve 55 is detected by a mixing temperature detecting means 56 such as a thermistor or a thermocouple. All outputs of these detection values are input to the control device 29.

  In the fuel cell system described above, the fuel gas valve 16, the DC / DC converter 2, the DC / AC inverter 4, the bidirectional DC / DC converter 45, the reheating device 10, and the electromagnetic valve 59 are controlled by the control device 29. Is done. The control device 29 outputs a fuel gas valve opening command 43, pulse commands 40, 42 and 50 and valve opening commands 34 and 60. The controller 29 receives a later-described system hot water supply output temperature command 53 from an interface device 52 that is input by the driver. As the interface device 52, a remote controller, a personal computer, a portable communication terminal, or the like can be used. Further, for transmission of the system hot water supply output temperature command 53, a signal line, wireless communication, the Internet, or the like can be used.

  FIG. 2 is a functional block diagram of a control device (system output control device) 29 according to an embodiment of the present invention.

  The phase / voltage detection means 102 detects the AC voltage phase 107 and the AC voltage amplitude 108 from the AC voltage detection value 36. The interconnection current control means 103 sends a pulse command 42 to the DC / AC inverter 4 that controls the interconnection current based on the AC voltage phase 107, the AC voltage amplitude 108, the interconnection current detection value 35, and the DC voltage detection value 41. Output. The received power calculation means 101 obtains the received power 106 by the product of the respective effective values of the received current detection value 37 and the AC voltage detection value 36.

  The system output calculation means 104 calculates a fuel cell current command 109, a storage battery current command 114, and a fuel gas valve opening command 43 based on the received power 106, the stored heat amount determination value 112, the storage battery voltage 49, and the charge amount 51. The fuel cell current control means 105 outputs a pulse command 40 based on the fuel cell current command 109 and the fuel cell current detection value 39. Based on the pulse command 40, the DC / DC converter 2 that controls the fuel cell current controls power supply from the fuel cell 1. Further, the storage battery current control means 113 outputs a pulse command 50 based on the storage battery current command 114 and the storage battery current detection value 48. The bidirectional DC / DC converter 45 that controls the storage battery current performs charge / discharge control of the storage battery 44 based on the pulse command 50.

  The heat storage amount determination (detection) means 110 determines the heat storage amount (hot water storage amount) of the hot water storage tank 5 based on the plurality of water temperature detection values 30, and outputs a livestock heat amount determination (detection) value 112. Further, the reheating command means 111 transmits a reheating command 34 to the reheating device 10 when the stock heat quantity determination value 112 is equal to or less than a predetermined value to prevent hot water from running out. The hot water supply control means 115 outputs a mixed valve control command 57 and a valve opening / closing command 60 based on the received system hot water supply output temperature command 53 and hot water filling information. Here, the mixing valve control command 57 is calculated as an operation amount of feedback control that makes the mixed temperature detection value 58 coincide with the system hot water supply output temperature command 53 or the hot water filling temperature command. Further, the valve opening / closing command 60 is instructed to complete the filling of the bathtub that is a part of the domestic heat load 11 at the filling time.

  FIG. 3 is a functional block diagram of the heat storage amount determination means 110 according to an embodiment of the present invention.

  Inside the hot water storage tank 5, water is distributed in two layers, a high temperature on the upper side and a low temperature on the bottom side. (Hot water storage amount) can be determined. The amount of water in the high temperature layer is determined by the water level of the water temperature detecting means 12, and in this embodiment, the case where the water temperature detectors 121 to 123 of the water temperature detecting means 12 are set to three points will be described. The water temperature comparators 321 to 323 compare the water temperature detection values 301 to 303 with predetermined water temperature threshold values, respectively, and output 1 if the threshold value is equal to or higher than the threshold value and 0 if it is lower than the threshold value. Therefore, if the sum of the outputs of all the water temperature comparators 321 to 323 is multiplied by a predetermined coefficient by the multiplier 33, the animal heat quantity determination value 112 can be obtained.

  Here, if the water temperature detectors 121 to 123 are installed at positions at which the hot water storage tank volume is equally divided, for example, at intervals of 10 L, and each volume value 10 L is equally used as the coefficient of the coefficient unit 33, the amount of heat stored in the hot water storage tank 5. Can be determined. For example, as shown in FIG. 3, if the values of the three water temperature detection values 301 to 303 are 65 ° C., 65 ° C., and 15 ° C. from the upper side, the livestock heat amount determination value 112 is 20L. In the present embodiment, the three water temperature detectors 121 to 123 are used. However, if the number of water temperature detectors is increased and the interval in the height direction is narrowed, the heat storage of the hot water storage tank 5 can be performed with higher accuracy. The amount can be determined.

  FIG. 4 is a functional block diagram of the system output calculation means 104 according to an embodiment of the present invention.

  The difference between the received power 106 and the received power threshold 310 becomes the storage battery output power command 311 and is input to the storage battery current conversion means 312. In the storage battery current conversion means 312, the storage battery output power command 311 is multiplied or divided by an arbitrary conversion coefficient such as the voltage detection value 49 to convert the storage battery output power command 311 into the storage battery current command 114 and output to the storage battery current control means 113. To do.

  The load power detection value 307 obtained by adding the fuel cell power command 306, the storage battery output power command 311 and the received power 106 is converted into a load power value 308 via the filter 320 that removes steep fluctuations, Input to the battery output calculation means 302. For example, a first-order lag filter is used as the filter 301.

  The fuel cell output calculation means 302 calculates a fuel cell output command 309 using the load power value 308, the stock heat quantity determination value 112, and the charge amount 51, and the fuel gas flow rate conversion means 324 calculates the fuel gas valve opening degree command 43. Convert to

  Since the fuel gas 15 requires a predetermined time to become stable when the fuel gas valve opening command 43 is changed, the fuel cell output command 309 is sent to the fuel cell via the delay means 304 that takes into account the time until stabilization. The battery power command 306 is output. The fuel cell power command 306 is converted into the fuel cell current command 109 by multiplying or dividing an arbitrary conversion coefficient such as the voltage detection value 38 or the like in the fuel cell current conversion unit 305, and is sent to the fuel cell current control unit 105. Entered.

  FIG. 5 is a functional block diagram of the fuel cell output calculation means 302 according to an embodiment of the present invention.

  The load power comparator 316 creates a fuel cell output that follows the load power. As indicated by the vertical axis in the load power comparator 316, assuming that the rated output power of the fuel cell 1 is 100%, the fuel cell 1 has discrete partial load outputs at intervals of about 20 to 30%. Give it. When the load power value 308 increases, the load power value 308 moves in an increasing direction on a thick line that falls within the range of the slope 1 indicated by the diagonal lines, while when the load power value 308 decreases, the range above the slope 1 line. Move in a decreasing direction on the thick line that fits in.

  The charge amount compensator 313 adjusts the fuel cell output in order to maintain the charge amount 51 of the storage battery (secondary battery) 44 within an appropriate range. For example, when the charge amount 51 tends to be overcharge of 70% or more, the charge amount compensator 313 outputs -25% and suppresses the output of the fuel cell 1. As a result, discharge of the secondary battery 44 is promoted, and the overcharge state can be released. Further, the sum of the load power comparator 316 and the charge amount compensator 313 is limited to, for example, 0% to 100% by the output limiter 317, and then becomes the load following fuel cell output 315.

  Moreover, the hot water supply demand prediction means 318 calculates hot water supply demand prediction data 319 within a future 24 hours by a predetermined method based on the stock heat quantity determination value 112. The overall controller 314 determines a fuel cell output command 309 by a predetermined calculation based on remote control information such as hot water supply demand prediction data 319, load following fuel cell output 315, livestock heat amount determination value 112, and system hot water supply output temperature command 53. To do.

  FIG. 6 is a conceptual diagram of calculation of hot water supply demand prediction data 319 according to an embodiment of the present invention. This is performed inside the hot water supply demand prediction means 318 of FIG. 5, and calculates hot water supply demand prediction data 319 for one day based on past hot water supply demand information. The livestock heat amount determination value 112 increases or decreases with the recovery of exhaust heat during power generation of the polymer electrolyte fuel cell (PEFC) system or the supply of hot water inside the hot water storage tank 5 to the mixing valve 55. The hot water supply demand prediction means 318 captures a period in which the livestock heat quantity determination value 112 monotonously decreases in the time change of the livestock heat quantity determination value 112, and displays hot water supply demand information such as the time of the monotonous decrease start and the hot water supply demand in the monotonously decreasing period It stores sequentially as a hot water supply demand history for a predetermined period. Here, the predetermined period may be, for example, the past week, the past month, or the past year. Thereafter, the hot water supply demand history is classified based on time data into 48 time zones obtained by dividing 0:00 to 24:00 at 30 minute intervals, and the hot water supply demand is averaged by a predetermined averaging process for each time zone. Thus, the hot water supply demand prediction data 319 for every 48 time zones is calculated. This can be used as a predicted value of the domestic heat load 11. The predetermined averaging process may be based on a statistical method such as moving average. In addition to applying to the entire history of the predetermined period, the predetermined averaging process is applied to the history extracted by day type such as day of the week, season, and holidays. May be.

  Generally, after the output change of the fuel cell 1, an output change prohibition time of several minutes is provided for stabilizing the output. For example, if the output change prohibition time is 20 minutes, a sufficient stabilizing effect can be obtained. When the output control of the fuel cell 1 is performed based on the hot water supply demand prediction data 319, if the output change accompanying the update of the hot water supply demand prediction data 319 is shorter than the output change prohibition time, the stability of the fuel cell 1 is affected. . Moreover, when the space | interval of the hot water supply demand prediction data 319 is as long as several hours or more, the time resolution of prediction deteriorates and affects accuracy. Accordingly, the hot water supply demand prediction data 319 can be obtained in the time zone divided at intervals of 20 minutes to 30 minutes to obtain prediction data suitable for the fuel cell system.

  With the hot water supply demand prediction method described above, the hot water supply to the domestic heat load 11 is detected with a low-loss temperature sensor, compared to the case where the flow rate of hot water to the domestic heat load 11 is detected and the hot water supply demand is predicted based on this flow rate. Since the demand can be predicted, a highly efficient fuel cell system can be provided.

  When installing cogeneration systems in individual households and using electricity and heat, the demand for electricity and heat is not uniform depending on the family structure and seasons. Driving is required. Since household electric power demand largely fluctuates with respect to the average value per day, an operation algorithm (mode 1) that switches output following electric power fluctuation is common. Priority is given to hot water supply in households with high heat demand, such as in cold regions, and rated output operation is continued until the hot water storage tank 5 is filled with hot water, and surplus power is also supplied by a heater installed in the hot water storage tank 5 or the circulating water path 7. An operation algorithm (mode 2) that converts heat energy is also used. However, the cogeneration system is characterized by a high overall efficiency that combines the two energies of electricity and heat, so that when it is operated only for electricity or heat, it can save energy and reduce utility costs. There is a possibility that it cannot be obtained sufficiently. Therefore, in the operation algorithm (mode 3) that improves the energy saving effect or the operation algorithm (mode 4) that improves the utility cost reduction effect, the optimum output follows the power demand fluctuation based on the prediction of heat demand. As described above, correction is performed by a predetermined calculation. The above four driving algorithms can be selected by the driver from the interface device 52, thereby providing a highly convenient fuel cell system. For example, when it is predicted that a life pattern that is greatly different from the prediction is performed while driving in the mode 3 using the prediction, by switching to the mode 2 that does not use the prediction, the appropriate fuel cell 1 Can provide output operation.

  FIG. 7 is an example of an operation / display surface of a remote controller as the interface device 52 according to the embodiment of the present invention.

  The remote controller is provided with the following operation unit and display unit. First, there is an operation / stop button 401 for operating / stopping the PEFC system, a time display 402 for displaying the current time, and an operation mode setting unit 403 for selecting any one of four-mode operation algorithms. Next, an output display unit 404 for displaying the power output, the received power, the load power, the utility cost reduction effect, the energy saving effect, etc., and the heat storage amount (hot water storage amount) display indicating the degree of the livestock heat amount judgment value 112 of the hot water storage tank 5 There is a part 405. Also, a hot water supply output temperature setting unit 406 for setting an output temperature command for system hot water supply, automatically selecting whether or not the bathtub has a hot water filling function, and the amount of hot water filling, hot water temperature, hot water filling when the bathtub hot water filling function is provided A hot water filling setting unit 407 for setting the time, a maintenance display unit 408 for displaying the life, maintenance, the remaining amount of the fuel tank, and the like. Further, a navigation display unit 409, a DSS setting unit that selects DSS (daily start / stop: with one or more start / stop operations per day) operation / continuous operation and sets the start time and stop time of the DSS operation 410. A key time setting unit 411 for selecting a key time period is provided.

  The DSS operation refers to an operation in which the operation time zone is scheduled and the start / stop is performed once or more per day, and the other continuous operation refers to an operation that does not stop except during an abnormality. In addition, the navigation display unit 409 displays the energy saving effect and the utility cost reduction effect due to the use of hot water in the hot water storage tank 5 and the use of the electric power load, and the driver's desire for hot water supply is displayed. In addition to display, notification may be made by voice. Furthermore, the key time period is a time period that should be noted in the control of this system, such as cooking and bathing, where a large demand for hot water supply is expected within a day. It is assumed that the key time period can be set and input from the remote controller 52 when the key time period is predicted from the normal life. In addition, the start time, stop time, and key time period when the DSS operation is selected are selected from 48 times obtained by dividing 24 hours a day by 30 minutes, for example.

FIG. 8 is a conceptual diagram of processing steps for changing the hot water supply demand prediction data 319 when the hot water filling function is set in the interface device 52 according to the embodiment of the present invention. Of hot water demand prediction data 319 shown in FIG. 6, the interface device and the hot-water demand prediction data 319 for time period t p that belongs set hot water filling preset time in 52, required to hot water filling settings set by the interface device 52 Compare the amount of hot water L p of hot water storage tanks. Then, the larger one of the new hot-water demand prediction data 319 of the time zone t p. Here, hot water filling amount set by the interface unit 52 L y, hot water filling temperature T y, when the hot water temperature T tank, and tap water temperature T W of the hot water storage tank, L p is be obtained by (1) Can do. According to the processing steps shown in FIG. 8, the heat storage amount required for water filling (the amount of hot water storage) L p can be reliably ensured.

Lp = Ly × (Tp−Tw) / (Ttank−Tw) (1)
FIG. 9 is a conceptual diagram of processing steps for changing the hot water supply demand prediction data 319 when the key time period is set in the interface device 52 according to the embodiment of the present invention. A case where two key time periods T k1 and T k2 are set for the hot water supply demand prediction data 319 shown in FIG. 7 is shown. In this case, as shown in FIG. 9, the hot water supply demand prediction data 319 in the key time setting time zone changes the time data to a predetermined time in the key time time zone and changes the usage data in the key time time zone. Change to sum. Here, for example, the central time or the start time of the key time setting time zone is used as the predetermined time. According to the change processing step shown in FIG. 9, the prediction error can be suppressed as compared with the case where the key time period in which the hot water supply demand can be predicted in advance is discretized at intervals of 30 minutes.

  FIG. 10 is a control processing flowchart of the overall controller 314 according to the embodiment of the present invention.

  The overall controller 314 checks the state of the remote control run / stop button 401 in step 101. If the result of step 101 is the operating state, the start standby state is determined in a predetermined start standby determination step 102, and then the start standby state is confirmed in step 103. If the result of step 103 is not in the standby state, the setting in the operation mode setting unit 403 of the remote control is confirmed in step 104. If the result of step 103 is mode 2, the fuel cell output command 309 is set to 100% output, and then a full tank is determined in step 109. If the result of step 103 is an operation mode other than mode 2, the fuel cell output command 309 is set to the load following fuel cell output 315, and then the setting in the operation mode setting unit 403 of the remote control is confirmed again in step 107 To do. If the result of step 107 is mode 1, the process proceeds to step 109. If the result of step 107 is other than mode 1, the predetermined hot water supply demand prediction control step 108 is performed, and then the process proceeds to step 109. In step 109, it is determined whether or not the stock heat quantity determination value 112 is full. If the determination result in step 109 is full, the fuel cell output command 309 is set to the minimum partial load output, and then predetermined navigation display is performed on the navigation notification (display) unit of the remote control in step 111. If it is determined in step 101 that the vehicle is not in an operating state, if it is determined in step 103 that it is in a standby state, if it is determined in step 109 that it is not full, and if navigation is terminated in step 111, the control flow The process is restarted from the top step 101.

In the start standby determination step 102, the start standby is determined based on the setting information of the DSS setting unit 410 of the interface device 52 in the mode 1 and the mode 2, and the hot water supply demand prediction data 319 is used in the mode 3 and the mode 4. The activation standby is determined by the calculated operation. The determination of the full state of the step 9 determines heat storage amount judgment value 112 with full state case were predetermined heat storage amount threshold H max or more. When the hot water storage in the hot water storage tank 5 becomes full, the secondary side inlet temperature of the heat exchanger 6 rises and heat cannot be sufficiently recovered, and the overall efficiency decreases. Therefore, if navigation notification (display) 111 that urges the user to use hot water can be performed to prompt the user to use the hot water, it is possible to avoid the full tank condition and continue the operation without lowering the overall efficiency.

FIG. 11 shows an algorithm of hot water supply demand prediction control step 108 using hot water supply demand prediction data 319 in mode 3 and mode 4 according to an embodiment of the present invention. In FIG. 11, the hot water supply demand prediction data 319 with the horizontal axis as time elapses is indicated by hatched bar graphs L <b> 1 to L <b> 2 and the livestock heat amount determination value 112 is indicated by a thick solid line. H 100 indicates an average heat output per unit time generated by the heat exchanger 6 when the fuel cell 1 generates power at the rated maximum output. The point A after in the figure from the position obtained by adding L1 to hot water demand L2 at time t2, the average heat output H heat storage amount judgment value 112 than a line drawn dashed with a slope of 100 is below. That is, unless the fuel cell 1 is operated at the rated maximum output from the time tA at the point A to the time t2, the hot water supply demands L1 and L2 cannot be supplied to the prediction data 319. When the amount of livestock heat (hot water storage) is insufficient for the domestic heat load 11 and cannot be supplied, the reheating device 10 is operated to supply hot water, but the reheating device 10 is generally more efficient than the energy supply by the fuel cell 1. Since it is low, the energy-saving effect may deteriorate. Therefore, when the condition of point A is satisfied, if the fuel cell 1 is operated at the rated maximum output until time t2 and heat is supplied from the fuel cell 1 without operating the reheating device 10, the energy saving effect is high. Driving can be realized.

  FIG. 12 shows a conceptual diagram of an algorithm of the activation standby determination step 102 (FIG. 10) in mode 3 and mode 4 according to an embodiment of the present invention. When the hot water storage tank 5 is full, or when the amount of heat storage reaches one day of the hot water supply demand prediction data, even if the fuel cell 1 is stopped, the supply balance can be achieved. Therefore, even if the fuel cell 1 is operated, the heat cannot be sufficiently recovered and the overall efficiency is lowered, and such low efficiency operation affects the energy saving effect and the utility cost reduction effect. The operation of the fuel cell 1 is made to wait as appropriate. However, once the operation is put on standby (pause), a standby loss or a start-up loss occurs at the time of standby or restart, so that it is better to continue the operation of the fuel cell 1 with the lowest partial load output without waiting. There may be situations where it is more advantageous than waiting. For this reason, using hot water supply demand prediction data 319, it is determined which is more effective when the standby is performed or when the operation is continued with the lowest partial load output.

In FIG. 12, the elapsed time is plotted on the horizontal axis, the hot water supply demand prediction data 319 is indicated by the shaded bar graphs L3 to L5, the livestock heat amount determination value 112 is indicated by a bold solid line, and the hot water storage tank 5 is filled with hot water at point B. The concept of standby (stop) determination in the case of becoming is shown. H X1 and H X2 indicate the gradient of the increase in the heat output per unit time generated in the heat exchanger 6 when the fuel cell 1 generates power at the predetermined partial load outputs X1 and X2. . The heat storage amount threshold value H max is a heat storage amount equivalent to a full tank of the hot water storage tank 5. Here, the minimum partial load output capable of obtaining an energy saving effect is selected as the predetermined partial load output X1, and the minimum partial load output capable of reducing the utility cost is selected as the other partial load output X2. . That is, the two slanted broken lines shown in the figure indicate the limits of the downtime that can be handled by the respective partial load outputs X1 and X2 in order to supply the hot water supply demand prediction data 319.

Initially, the restart time when waiting (pause) at point B is estimated. The predicted value 112E of the stock heat quantity determination value 112 at an arbitrary C1 point after the B point is lower than the actual broken line of the slope H X1 due to the minimum partial load output that can obtain the energy saving effect after the C1 point. Therefore, in order to be able to supply the hot water supply demand prediction data 319 with the minimum partial load output X1 with which an energy saving effect can be obtained, it is necessary to restart at this time point C1, and this time is assumed to be the estimated time t C1 . Similarly, the estimated restart time t C2 is also obtained for the solid broken line H X2 of the gradient with the minimum partial load output that can obtain the effect of reducing utility costs.

Next, in the case of mode 3, the energy saving effect is obtained when the operation is waited based on the difference between the estimated restart time t C1 and the current time t B and when the operation is continued with the minimum partial load output without waiting. Compare. In the case of mode 4, based on the difference between the estimated restart time t C2 and the current time t B , the utility cost reduction effect is obtained when the operation is waited and when the operation is continued with the minimum partial load output without waiting. Compare. As a result of the comparison, it is possible to improve the energy saving effect or the utility cost reduction effect by selecting an advantageous operation of either standby or continuous operation without waiting.

  Thus, the fuel cell system which can improve the energy-saving effect or the utility cost reduction effect can be realized by determining the operation algorithm for each of the modes 1 to 4 and controlling the output of the fuel cell 1 based on the hot water supply demand prediction data 319. .

  Further, according to the prediction of the hot water supply demand according to this embodiment, it is possible to predict the domestic heat load 11 with a temperature sensor having a lower loss than when a hot water flow rate sensor is provided and the hot water flow rate to the domestic heat load 11 is detected. Therefore, a highly efficient fuel cell system can be provided.

1 is an overall configuration diagram showing an overview of a fuel cell system according to an embodiment of the present invention. The functional block diagram of the system output control apparatus in FIG. The functional block diagram of the heat storage amount determination means in FIG. The functional block diagram of the system output calculating means in FIG. The functional block diagram of the fuel cell output calculating means in FIG. The conceptual diagram of the calculation of the hot water supply demand prediction means in FIG. FIG. 2 is an example of an operation / display surface of the interface device (remote controller) in FIG. 1. The processing step conceptual diagram regarding the hot water filling function of the hot water supply demand prediction means of FIG. The processing step conceptual diagram regarding the key time function of the hot water supply demand prediction means of FIG. FIG. 6 is a control processing flowchart of the overall controller in FIG. 5. The conceptual diagram of the algorithm of the hot water supply demand prediction control step in FIG. The conceptual diagram of the algorithm of the starting stand-by judgment step in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... DC / DC converter, 3 ... DC capacitor, 4 ... DC / AC inverter, 5 ... Hot water storage tank, 6 ... Heat exchanger, 7 ... Circulating water path, 8 ... Circulating water tank, 9 ... Intake water Means, 10 ... reheating device, 11 ... domestic heat load, 12 ... water temperature detection means, 121-123 ... temperature detector, 13 ... water treatment device, 14 ... fuel gas production means, 15 ... fuel gas, 16 ... fuel Gas valve, 17 ... Fuel cell voltage detection means, 18 ... Fuel cell current detection means, 19 ... DC voltage detection means, 20 ... Reactor, 21 ... Capacitor, 22 ... Interconnection current detection means, 23 ... AC voltage detection means, 24 ... Shut-off input means, 25 ... Domestic power load, 26 ... Received current detection means, 27 ... Domestic power receiving panel, 28 ... Commercial power supply, 29 ... Control device (system output control device), 30, 301-303 ... Water temperature detection 31 ... circulation pump, 321-323 ... water temperature comparator, 44 ... storage battery, 45 ... bidirectional DC / DC converter, 46 ... storage battery current detection means, 47 ... storage battery voltage detection means, 52 ... interface device (remote control), 55 ... mixing valve, 56 ... mixing temperature detection means, 59 ... solenoid valve, 61 ... manual mixing valve, 101 ... received power calculation means, 102 ... phase / voltage detection means, 103 ... interconnection current control means, 104 ... system output Calculation means 105 ... Fuel cell current control means 110 ... Heat storage amount determination means 111 ... Recharge command means 113 ... Storage battery current control means 115 ... Hot water supply control means 302 ... Fuel cell output calculation means 324 ... Fuel gas Flow rate conversion means 304 ... Delay means 305 ... Fuel cell current conversion means 312 ... Storage battery current conversion means 313 ... Charge amount compensator 314 ... Body controller, 316 ... load power comparator, 317 ... output limiter, 318 ... hot water supply demand prediction means, 319 ... hot water supply demand prediction data, 401 ... run / stop button, 402 ... time display unit, 403 ... operation mode setting unit, 404 ... Output display unit, 405 ... Heat storage amount (hot water storage amount) display unit, 406 ... Hot water supply output temperature setting unit, 407 ... Hot water filling setting unit, 408 ... Maintenance display unit, 409 ... Navigation notification (display) unit, 410 ... DSS Setting unit, 411... Key time setting unit, L1 to L5.

Claims (20)

  1.   A fuel cell, a hot water storage tank for storing hot water heated by heat generated by the power generation operation of the fuel cell, a plurality of temperature detectors provided in the hot water storage tank for detecting the water temperature in the hot water storage tank, and detection of these temperatures A fuel cell system comprising heat storage amount determination means for determining the amount of heat stored in the hot water storage tank based on the output of the storage device, and control means for controlling the output of the fuel cell according to the heat storage amount determination result.
  2.   2. The fuel cell system according to claim 1, wherein a plurality of the temperature detectors are arranged at intervals in the height direction of the hot water storage tank.
  3.   2. The fuel cell system according to claim 1, further comprising means for calculating hot water supply information including information related to time and information related to the amount of hot water supply, based on a decrease in the heat storage amount determined by the heat storage amount determination means.
  4.   2. The hot water supply amount calculating means for calculating a hot water supply amount by a decrease in the heat storage amount determined by the heat storage amount determining means according to claim 1, and a hot water supply history storing means for storing past hot water supply amount information by the hot water supply amount calculating means as a hot water supply history And a hot water supply prediction means for calculating future hot water supply prediction data based on the hot water supply history.
  5.   5. The fuel cell system according to claim 4, wherein the hot water supply prediction means includes means for calculating hot water supply prediction data for each of a plurality of time zones obtained by dividing 24 hours at predetermined intervals.
  6.   5. The apparatus according to claim 4, further comprising an interface device capable of inputting data from outside, wherein the hot water prediction means calculates the hot water prediction data for each of a plurality of time zones based on data input from the interface device. A fuel cell system characterized by that.
  7.   In Claim 1, means for calculating hot water supply amount information based on a decrease in the amount of stored heat determined by the heat storage amount determination means, hot water supply history storage means for storing past hot water supply amount information by the hot water supply amount calculation means as hot water supply history, Hot water prediction means for calculating future hot water supply prediction data based on the hot water supply history, and an interface device capable of inputting data from the outside, wherein the hot water prediction means is based on the data input from the interface device. A fuel cell system configured to change a calculation method of prediction data.
  8.   In Claim 1, means for calculating hot water supply amount information based on a decrease in the amount of stored heat determined by the heat storage amount determination means, hot water supply history storage means for storing past hot water supply amount information by the hot water supply amount calculation means as hot water supply history, A hot water supply prediction means for calculating future hot water supply prediction data based on the hot water supply history and an interface device capable of inputting data from the outside, the hot water prediction means is based on data input from the interface device, A fuel cell system configured to change the hot water supply prediction data related to a time zone.
  9.   2. The hot water supply amount calculating means for calculating a hot water supply amount by a decrease in the heat storage amount determined by the heat storage amount determining means according to claim 1, and a hot water supply history storing means for storing past hot water supply amount information by the hot water supply amount calculating means as a hot water supply history And a hot water supply prediction means for calculating future hot water supply prediction data based on the hot water supply history, and a battery output changing means for changing the output of the fuel cell in accordance with the hot water supply prediction data. .
  10.   10. The battery output changing means according to claim 9, wherein the fuel cell is in a power generation state, and the output of the fuel cell is increased or decreased based on a relationship between the hot water supply prediction data and the amount of heat stored in the hot water storage tank. A fuel cell system.
  11.   10. The fuel cell according to claim 9, wherein the battery output changing means is based on the fact that the fuel cell is in a power generation state and the amount of heat stored in the hot water storage tank is less than a predetermined relationship with respect to the hot water supply prediction data. The fuel cell system is characterized by increasing the output of the engine to the rated maximum output.
  12.   10. The battery output changing means according to claim 9, wherein the fuel cell is in a power generation state, and the heat storage amount of the hot water storage tank is below a predetermined relationship with respect to the hot water supply prediction data within 24 hours in the future. And increasing the output of the fuel cell to the rated maximum output.
  13.   2. The hot water supply amount calculating means for calculating a hot water supply amount by a decrease in the heat storage amount determined by the heat storage amount determining means according to claim 1, and a hot water supply history storing means for storing past hot water supply amount information by the hot water supply amount calculating means as a hot water supply history A hot water supply prediction means for calculating future hot water supply prediction data based on the hot water supply history, and a fuel cell start / stop means for starting and stopping the fuel cell in accordance with the hot water prediction data .
  14.   14. The fuel cell start / stop unit according to claim 13, wherein when the fuel cell is in a power generation state, a continuation standby determination unit that determines whether to continue power generation or standby of the fuel cell based on the hot water supply prediction data. A fuel cell system characterized in that the fuel cell is continuously operated or stopped according to the determination result of the continuous standby determination means.
  15.   14. The fuel cell start / stop means according to claim 13, wherein the fuel cell is in a power generation state, and the amount of heat stored after the previous start of the fuel cell system exceeds hot water prediction data for the next 24 hours. A length of the power generation standby time based on a restart time when the system is in a power generation standby state is predicted, and power generation of the fuel cell is continued when the predicted power generation standby time is shorter than a predetermined time. A fuel cell system.
  16.   2. A hot water supply amount calculating means for calculating a hot water supply amount by a decrease in the heat storage amount determined by the heat storage amount determining means according to claim 1, and a hot water supply history storing means for storing past hot water amount information by the hot water supply amount calculating means as a hot water supply history. A hot water prediction means for calculating future hot water supply prediction data based on the hot water supply history, a first operation control algorithm for changing the output of the fuel cell based on the hot water prediction data, and the hot water prediction data irrespective of the hot water prediction data A second operation control algorithm for controlling power generation of the fuel cell; an interface device capable of inputting data from the outside; and the fuel by the first or second operation control algorithm based on data input by the interface device. A fuel cell system comprising operation control means for controlling the operation of a battery.
  17.   2. A hot water supply amount calculating means for calculating a hot water supply amount by a decrease in the heat storage amount determined by the heat storage amount determining means according to claim 1, and a hot water supply history storing means for storing past hot water amount information by the hot water supply amount calculating means as a hot water supply history. And a hot water supply prediction means for calculating future hot water supply prediction data based on the hot water supply history, a first operation control mode for following the load power and suppressing the received power, and a second for maximizing the amount of heat stored in the hot water storage tank. Of these operation control modes, a third operation control mode that suppresses energy consumption using the hot water supply prediction data, a fourth shift control mode that suppresses utility costs using the hot water supply prediction data, and And a fuel cell system comprising: input means for selectively inputting one; and operation control means for controlling the operation of the fuel cell in one mode input by the input means. Beam.
  18.   2. The fuel cell system according to claim 1, further comprising notification means for notifying that the heat storage amount is sufficient when the heat storage amount exceeds a predetermined amount.
  19.   A step of storing hot water heated by heat generated by power generation operation of the fuel cell in a hot water storage tank, and a step of detecting the water temperature in the hot water storage tank by a plurality of temperature detectors arranged at intervals in the height direction of the hot water storage tank; Based on the output of these temperature detectors, the step of determining the amount of heat stored in the hot water storage tank, the step of calculating the amount of hot water supply by reducing the determined amount of stored heat, and the past information of this hot water supply amount is accumulated as the hot water supply history A step of calculating future hot water supply prediction data based on the hot water supply history, and a step of controlling the operation of the fuel cell based on the heat storage amount and the hot water prediction data Battery system control method.
  20.   A fuel cell, a hot water storage tank that stores hot water warmed by heat generated by the power generation operation of the fuel cell, and a plurality of temperature detectors that are arranged at intervals in the height direction of the hot water storage tank to detect the water temperature in the hot water storage tank And a heat storage amount determination means for determining the amount of heat stored in the hot water storage tank based on the output of these temperature detectors, and a hot water supply amount calculation means for calculating the amount of hot water supply based on the decrease in the heat storage amount determined by the heat storage amount determination means A hot water supply history storage means for storing past hot water supply information by the hot water supply amount calculation means as a hot water supply history, a step of calculating future hot water supply prediction data based on the hot water supply history, and the stored heat amount and the hot water supply prediction data. A fuel cell system control device comprising: an operation control means for controlling the operation of the fuel cell.
JP2005105929A 2005-04-01 2005-04-01 Fuel cell system, its control method, and its control device Pending JP2006286450A (en)

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