JP4656521B2 - Cogeneration system - Google Patents

Description

  The present invention relates to a cogeneration system.

  The cogeneration system includes a power generation device that supplies power to the load device, an operation control device that controls the power generation device so as to achieve a power generation amount according to a power generation amount instruction value, and hot water that recovers exhaust heat from the power generation device. What is equipped with the hot water storage tank which stores hot water is known.

  As an example of this cogeneration system, there is a cogeneration system disclosed in Patent Document 1. In this cogeneration system, the fuel cell operation is based on once / day (hereinafter referred to as “on / off once control”), and the daily hot water consumption according to the hot water consumption model pattern by time zone is continuous for one day. When exceeding the amount of hot water stored by exhaust heat recovery when operating the fuel cell at a constant operating rate or above, or when exceeding the amount of hot water stored by converting the surplus power into heat by means of electric heat conversion means and adding to the exhaust heat recovery, The control is stopped once on and off, and the fuel cell is operated continuously for one day. According to this, normally, on / off control is performed once, but under conditions where the hot water supply load is large, such as in winter, the on / off control is stopped and the number of times the fuel cell is started is reduced by performing continuous operation throughout the day. Therefore, the start-up energy loss of the fuel cell can be prevented, and the intermittent operation that affects the deterioration of the fuel cell can be reduced, so that the durability of the fuel cell can be improved.

  Another example is a cogeneration system disclosed in Patent Document 2. This cogeneration system is stored in a database dedicated to the time of going out (storage means 14 for storing data in a situation where demand is low), for example, when the home of a person living in a house having a fuel cell cogeneration system goes out It is possible to improve the operation efficiency of the cogeneration system having the fuel cell or the gas engine by performing the operation control exclusively for going out according to the data.

Specifically, for example, when the user goes out, the power demand decreases, and the operating efficiency of the fuel cell (FC) decreases. In such a case, when going out is predicted (predicting the time when the demand is below a predetermined value) and the predicted going out time is equal to or greater than the threshold, the efficiency is improved by stopping the fuel cell (FC). Judge and stop. At this time, the threshold for determining whether or not to stop (the threshold for going out time) is the startup energy required until the power demand recovers and restarts after stopping, and the operation continues without stopping. In this case, the power generation amount, the power purchase amount, and the primary energy consumption amount based on the gas consumption amount are set within a range that satisfies the condition that it is smaller.
JP 2005-38676 A JP 2005-09846 A

  By the way, in the cogeneration system described in Patent Document 1, switching between on / off once control and continuous operation throughout the day is controlled, and in the cogeneration system described in Patent Document 1, power generation is stopped during the outing time. Controls whether to continue or not. However, in any case, since the deterioration of exhaust heat recovery and deterioration of power generation efficiency due to secular change are not taken into account when switching is decided, the longer the period of use, the worse the energy saving effect and the more efficient operation can be achieved. There was a problem of disappearing. Also, in any case, when switching is decided, the variation in the amount of exhaust heat recovered and the variation in power generation efficiency are not taken into account. There was a problem that efficient driving was not possible.

  The present invention has been made to solve the above-described problems, and is affected by exhaust heat recoverability and power generation efficiency variation among products, deterioration of exhaust heat recovery amount due to secular change, and deterioration of power generation efficiency. It aims at providing the cogeneration system which maintained the energy-saving effect highly.

  In order to solve the above-described problem, the structural feature of the invention according to claim 1 is that the power generation device that supplies power to the load device and the power generation device is controlled so that the power generation amount corresponds to the power generation amount instruction value In a cogeneration system comprising an operation control device and a hot water storage tank for storing hot water recovered from the exhaust heat of the power generation device, power generation is stopped for calculating the energy saving effect when power generation of the power generation device is stopped in a predetermined time zone The energy saving effect calculating means, the power generation continuing energy saving effect calculating means for calculating the energy saving effect when the power generation of the power generator is continued in a predetermined time zone based on the learning value of the characteristics of the power generator, and both energy saving effect calculating means, respectively Comparing means for comparing the calculated energy saving effects and continuous power generation control to continue power generation of the power generation device or stopping power generation of the power generation device in a predetermined time zone And switching means for switching based on whether to implement the control to the comparison result by the comparison means is that with the.

  A structural feature of the invention according to claim 2 is that, in claim 1, the predetermined time zone is a low power consumption time zone in which the power consumption by the load device is small.

  Further, the structural feature of the invention according to claim 3 is that, in claim 2, the low power consumption time zone is the power in the daily power consumption pattern derived from the power consumption data measured and stored in advance. This is a time zone of the power consumption pattern in which the power consumption is smaller than the multiplication value obtained by multiplying the minimum value of the consumption by a predetermined value.

  According to a fourth aspect of the present invention, in any one of the first to third aspects of the invention, the characteristics of the power generation device include: a power generation amount of the power generation device and a fuel input amount that is input to the power generation device. Power generation amount-fuel input amount characteristic, and power generation amount-exhaust heat recovery amount characteristic, which is a correlation between the power generation amount of the power generation apparatus and the exhaust heat recovery amount recovered in the hot water storage tank.

  In the invention according to claim 1 configured as described above, the power generation stop energy saving effect calculating means calculates the energy saving effect when the power generation of the power generator is stopped in a predetermined time zone, and the power generation continuation energy saving effect calculating means is The energy saving effect when power generation of the power generator is continued in a predetermined time zone is calculated based on the learning value of the characteristics of the power generator, and the comparing means compares the energy saving effects calculated by the both energy saving effect calculating means. Then, the switching means switches between performing the continuous power generation control for continuing the power generation of the power generation apparatus or performing the power generation stop control for stopping the power generation of the power generation apparatus based on the comparison result by the comparison means in a predetermined time zone. . Therefore, it is possible to appropriately switch to an operation that has an energy saving effect based on the learning value of the characteristics of the power generation device in a predetermined time zone, so even if there is a variation in exhaust heat recovery performance and power generation efficiency for each product, Even if the exhaust heat recovery amount and power generation efficiency due to secular change deteriorate, it is possible to provide a cogeneration system that maintains a high energy-saving effect without being affected by it.

  In the invention according to claim 2 configured as described above, in the invention according to claim 1, the predetermined time zone is a low power consumption time zone in which the power consumption by the load device is small. Even in a fuel cell cogeneration system where the power generation efficiency is low when the power generation output is small, it is possible to carry out an efficient operation with a high energy saving effect.

  In the invention according to claim 3 configured as described above, in the invention according to claim 2, the low power consumption time zone is a power consumption pattern of one day derived from data of power consumption measured and stored in advance. The power consumption pattern is a time zone in which the power consumption is smaller than the product of multiplying the minimum value of the power consumption by a predetermined value, so the low power consumption time zone is appropriate according to the actual power consumption pattern. Can be derived.

  In the invention according to claim 4 configured as described above, in the invention according to any one of claims 1 to 3, the characteristics of the power generation device are input to the power generation amount of the power generation device and the power generation device. It is a power generation amount-fuel input amount characteristic that is a correlation with the fuel input amount, and a power generation amount-exhaust heat recovery amount characteristic that is a correlation between the power generation amount of the power generator and the exhaust heat recovery amount recovered in the hot water storage tank. Therefore, the energy saving effect can be improved more reliably.

  Hereinafter, an embodiment of a cogeneration system according to the present invention will be described. FIG. 1 is a schematic diagram showing an overview of this cogeneration system. In this cogeneration system, the power generation device 10 that supplies power to the load device 21, the hot water storage tank 30 that stores hot water from which the exhaust heat of the power generation device 10 is collected, and the power generation amount according to the power generation amount instruction value are obtained. And an operation control device 40 that controls the power generation device 10.

  The power generation device 10 is a fuel cell power generation device, and includes a power generator 11 that generates DC power, and a converter (for example, an inverter) 12 that converts the DC power supplied from the power generator 11 into AC power and outputs the AC power. ing. In addition to the fuel cell power generation device, the power generation device 10 may be configured by a prime mover such as a diesel engine, a gas engine, a gas turbine, or a micro gas turbine, and a generator driven by the prime mover.

  The generator 11 includes a reformer, a carbon monoxide reduction device (hereinafter referred to as a CO reduction device), and a fuel cell. In the reformer, the fuel supplied from the fuel supply device 13 is steam-reformed with water supplied from the water supply device 14 to generate a hydrogen-rich reformed gas, which is led to the CO reduction device. The CO reduction device reduces carbon monoxide contained in the reformed gas and leads it to the fuel cell. The fuel cell generates power using hydrogen in the reformed gas supplied to the fuel electrode and air that is an oxidant gas supplied to the air electrode.

  Between the fuel supply device 13 and the power generator 11, a flow meter 13a serving as a fuel input amount detecting means for detecting the amount of fuel input to the power generator 11 is provided. The flow meter 13a detects the detected fuel input amount. Is transmitted to the operation control device 40. Note that the amount of fuel input in the case of a fuel cell power generator refers to the amount of fuel supplied to the reformer.

  The converter 12 is connected to a plurality of load devices 21 installed at the power use place 20 via the power transmission line 15, and the AC power output from the converter 12 is supplied to each load device 21 as necessary. Has been supplied to. The converter 12 is provided with a wattmeter 10a that is a power generation output amount detecting means for detecting the power generation output amount output from the power generation device 10, and the wattmeter 10a sends the detected power generation output amount to the operation control device 40. It is supposed to send.

  The load device 21 is an electric appliance such as an electric lamp, iron, television, washing machine, electric kotatsu, electric carpet, air conditioner, and refrigerator. In addition, the power source 15 of the power company is also connected to the power transmission line 15 that connects the converter 12 and the power use place 20 (system connection), and the total power consumption of the load device 21 is determined by the power generation amount of the power generation device 10. When the amount exceeds, the insufficient power is received from the system power supply 16 and compensated. The wattmeter 22 is power consumption detection means for detecting the power consumption consumed by the load device 21, detects the total power consumption of all the load devices 21 used in the power usage place 20, This is transmitted to the operation control device 40.

  The generator 11 is connected to a cooling circuit 31 through which a heat medium for recovering exhaust heat of the generator 11 and cooling the generator 11 circulates. A heat exchanger 32 is disposed on the cooling circuit 31. On the other hand, a hot water circulation circuit 33 for heating hot water (hot water) in the hot water tank 30 is connected to the hot water tank 30 described later. A heat exchanger 32 is disposed on the hot water circulation circuit 33. The heat exchanger 32 performs heat exchange between the heat medium circulating in the cooling circuit 31 and the hot water circulating in the hot water circulation circuit 33. As a result, a pump (not shown) is driven during power generation by the power generator 11 so that the heat medium circulates in the cooling circuit 31 and hot water circulates in the hot water circulation circuit 33, so that the exhaust heat of the power generator 11 is exchanged with the heat medium and heat. The hot water is recovered as hot water through the vessel 32 and heated. For example, in the case of a fuel cell power generation device, the exhaust heat of the power generator 11 refers to exhaust heat of a fuel cell stack or exhaust heat of a reformer, and in the case of an engine power generation device, examples include exhaust heat of an engine. However, the present invention is not limited to this, and any recoverable exhaust heat such as heat of the generator itself can be used.

  The hot water tank 30 is provided with one columnar container, in which hot water is stored in a layered manner, that is, hot water in the upper part is the hottest and becomes lower as it goes to the lower part, and the hot water in the lower part is stored at the lowest temperature. It has become so. Hot water stored in the hot water tank 30 is derived from the upper part of the columnar container of the hot water tank 30, and water such as tap water from the water supply device 14 (low temperature water) so as to replenish the derived amount. Is introduced from the lower part of the columnar container of the hot water tank 30. Such a hot water tank 30 is installed near the power generation apparatus 10.

  In addition, a temperature sensor group 34 which is a remaining hot water amount detection sensor is provided inside the hot water tank 30. The temperature sensor group 34 is composed of a plurality (nine in this embodiment) of temperature sensors 34-1, 34-2, 34-3,..., 34-9, and is arranged in the vertical direction (vertical direction). It is arrange | positioned at equal intervals (distance of 1/8 of the vertical direction height in the hot water tank 30) along. The temperature sensor 34-1 is disposed on the inner upper surface of the hot water tank 30. Each of the temperature sensors 34-1, 34-2, 34-3,..., 34-9 detects the temperature of the liquid (hot water or water) in the hot water storage tank 30 at that position. The amount of remaining hot water in the hot water storage tank 30 is detected based on the detection result of the hot water temperature at each position by the temperature sensor group. The remaining hot water amount represents the remaining amount of hot water remaining in the hot water storage tank 30 that is equal to or higher than a predetermined temperature (for example, 60 ° C.). Therefore, for example, when each temperature sensor 34-1 to 34-3 detects 60 ° C. or more and each temperature sensor 34-4 to 34-9 detects less than 60 ° C., the remaining hot water amount detection sensor 34 Detects the amount of water (the amount of hot water) from the inner wall surface of the hot water tank 30 to the temperature sensor 34-3 as the amount of remaining hot water. The amount of remaining hot water at this time is 1/4 of the capacity of the hot water tank 30. Moreover, when each temperature sensor 34-1 to 34-4 detects 60 degreeC or more and each temperature sensor 34-5 to 34-9 has detected less than 60 degreeC, the remaining hot water detection sensor 34 is hot water storage. 3/8 of the capacity of the tank 30 is detected as the amount of remaining hot water.

  The amount of remaining hot water between the temperature sensor detecting 60 ° C. or more and the temperature sensor detecting less than 60 ° C. is based on the temperature gradient calculated by a plurality of upper and lower temperature sensors including these two temperature sensors and the distance between the sensors. Therefore, the remaining hot water amount in the hot water storage tank 30 can be calculated more accurately by adding up the calculated remaining hot water amounts between the sensors.

  A hot water supply pipe 35 is connected to the hot water tank 30. The hot water supply pipe 35 is provided with a gas water heater (not shown), a temperature sensor (not shown), and a flow rate sensor 36 which are auxiliary heating devices in order from the upstream side. The gas water heater heats hot water from the hot water storage tank 30 passing through the hot water supply pipe 35 to supply hot water. The temperature sensor detects the temperature of the hot water after passing through the gas water heater, and the detection signal is transmitted to the operation control device 40. That is, the hot water is heated by the gas water heater so that the temperature of the hot water detected by the temperature sensor becomes the set hot water temperature. Although not shown, tap water from the water supply device 14 is joined to the hot water supply pipe 35 between the outlet of the hot water tank 30 and the temperature sensor. Thereby, the temperature of the hot water from the hot water tank 30 is lowered. The flow rate sensor 36 detects the amount of hot water consumption (hot water supply amount) supplied from the hot water storage tank 30. A detection signal of the flow sensor 36 is transmitted to the operation control device 40. The operation control device 40 stores the received hot water consumption and creates / updates a hot water supply demand pattern.

  Connected to the hot water supply pipe 35 are a plurality of hot water use devices 26a installed in a hot water use place 25 that uses hot water stored in the hot water tank 30 as hot water supply. Examples of the hot water use device 26a include a bathtub, a shower, a kitchen (kitchen faucet), and a washroom (toilet faucet). The hot water supply pipe 35 is connected to a heat utilization device 26b installed in a hot water use place 25 that uses hot water in the hot water tank 30 as a heat source. Examples of the heat utilization device 26b include bathroom heating, floor heating, and a hot water reheating mechanism. The heat utilization device 26b may use the hot water in the hot water tank 30 directly or indirectly use the hot water in the hot water tank 30.

  The operation control device 40 has a microcomputer (not shown), and the microcomputer includes an input / output interface, a CPU, a RAM, and a ROM (all not shown) connected via a bus. The CPU executes a program corresponding to the flowcharts of FIGS. 2 to 10 to control power generation / stop switching and power generation amount (output power) of the power generation device. The RAM temporarily stores variables necessary for executing the program, and the ROM stores the program.

  Next, the operation of the above-described cogeneration system will be described with reference to FIGS. When the main power supply (not shown) is turned on, the operation control device 40 starts the program in step 100 and advances the program to step 102. The operation control device 40 presets a predetermined time period by the processing of steps 102 to 116, and determines whether to stop power generation or continue power generation in the predetermined time period. This process is performed once a day, for example.

  In step 102, the operation control device 40 executes the program in accordance with the low power consumption time zone prediction routine shown in FIG. 3, and predicts the time zone (predetermined time zone) of the low power consumption and stores the time zone. .

  The operation control device 40 reads the power consumption measured in advance and stored in association with the date and time for a predetermined period (for example, one week) (step 202), and averages the data for each time of day. The daily power consumption pattern is derived (step 204). The derivation result is shown in FIG. In FIG. 11, the horizontal axis indicates the time (hour) of the day from 0:00 to 24:00, and the vertical axis indicates the power consumption [W]. The operation control device 40 derives the minimum value as the minimum value Emin from the power consumption of the power consumption pattern derived in step 204 (step 206). Then, as shown in FIG. 11, the operation control device 40 compares the multiplication value (Emin × C) obtained by multiplying the minimum value Emin by the predetermined value C with the power consumption pattern derived in step 204, and calculates the power from the multiplication value. A time zone in which the consumption is reduced is predicted (derived) as a time zone for low power consumption and stored (step 208). This time zone is a time zone from time t1 to time t2. Thereafter, the process proceeds to step 210 to end the processing of this routine, and the program proceeds to step 104 shown in FIG.

  Next, in step 104, the operation control device 40 executes a program according to the fuel input amount characteristic learning routine shown in FIG. 4 and learns the fuel input amount characteristic based on the measurement data of the power generation amount and the fuel input amount. .

  The operation control device 40 reads the data of the power generation amount Eg and the fuel input amount Hf that are measured and stored in association with each other in advance for a predetermined period (for example, one week) (step 302), and based on these data, the power generation amount-fuel input An approximate expression of the quantity characteristic is derived (step 304). The data of the power generation amount Eg and the fuel input amount Hf read in step 302 is the power generation amount Eg generated by the power generation device 10 with respect to the fuel input amount Hf input to the power generation device 10, and every predetermined time (for example, 60 seconds). Measured and associated with each other and stored. The fuel input amount Hf is measured by the flow meter 13a, and the power generation amount Eg is measured by the power meter 10a.

  In step 304, the operation control device 40 derives an arithmetic expression indicating a correlation between the power generation amount and the fuel input amount based on the data read in step 302 using, for example, the least square method. The arithmetic expression is expressed by the following formula 1 as an approximate expression.

(Equation 1)
Y = a1 · X + b1

  Y is the amount of fuel input, and X is the amount of power generation. a1 is a constant represented by the following formula 2, and b1 is a constant represented by the following formula 3.

Here, n is the preliminary number of measured data read in step 302, Eg _i is the data of the measured power generation amount Eg the i-th, Hf _i is measured i th This is data of the injected fuel amount Hf. Eg￣ and Hf￣ are average values of all the measured power generation amounts Eg and fuel input amounts Hf, and are calculated from the following equations (4) and (5).

  FIG. 12 shows an example of an arithmetic expression showing a correlation between the power generation amount derived by such a method and the fuel input amount. In FIG. 12, the horizontal axis indicates the power generation amount [W], and the vertical axis indicates the fuel input amount [L / min]. The dots indicate the measurement data.

  Thereafter, the operation control device 40 proceeds to step 306 to end the processing of this routine, and proceeds the program to step 106 shown in FIG.

  Next, in step 106, the operation control device 40 executes a program according to the exhaust heat recovery amount characteristic learning routine shown in FIG. 5, and based on the measurement data of the power generation amount and the exhaust heat recovery amount, the exhaust heat recovery amount characteristic. To learn.

  The operation control device 40 reads the data of the power generation amount Eg and the exhaust heat recovery amount Hg measured and stored in advance for a predetermined period (for example, one week) (step 402), and based on the data, the power generation amount-exhaust An approximate expression of the heat recovery amount characteristic is derived (step 404). The data of the power generation amount Eg and the exhaust heat recovery amount Hg read in step 402 is the exhaust heat recovery amount Hg collected by the hot water with respect to the power generation amount Eg generated by the power generation apparatus 10, and is every predetermined time (for example, 60 seconds). Measured and associated with each other and stored. The power generation amount Eg is measured by the wattmeter 10a. The exhaust heat recovery amount Hg is an increased heat amount of the hot water in the hot water storage tank 30 and is calculated based on the following equation (6).

(Equation 6)
Waste heat recovery amount Hg = Increased heat amount of hot water x Specific heat [J / g · ° C]

  Here, the increased heat quantity of the hot water is the difference between the total heat quantity of the hot water in the hot water tank 30 before and after the increase in the remaining hot water quantity calculated based on the temperature distribution in the hot water tank 30 detected by the remaining hot water quantity detection sensor 34. It can be derived by taking The exhaust heat recovery amount Hg is determined by measuring the inlet temperature and outlet temperature of hot water (or the heat medium of the generator 11) of the heat exchanger 32 and hot water (or the generator 11) passing through the heat exchanger 32, respectively. It is also possible to measure the flow rate of the heat medium that passes through (3) and to derive using these measured values. The specific heat is the specific heat of hot water, that is, water, and here it is 4.18605 [J / g · ° C.].

  In step 404, the operation control device 40 derives an arithmetic expression indicating a correlation between the power generation amount and the exhaust heat recovery amount based on the data read out in step 402 using, for example, the least square method. The arithmetic expression is expressed by the following formula 1 as an approximate expression.

(Equation 7)
Y = a2 · X + b2

  Y is an exhaust heat recovery amount, and X is a power generation amount. a2 is a constant represented by the following formula 8, and b2 is a constant represented by the following formula 9.

Here, n is the preliminary number of measured data read in step 402, Eg _i is the data of the measured power generation amount Eg the i-th, Hg _i is measured i th This is data of the amount of exhaust heat recovered Hg. Eg￣ and Hg￣ are average values of all the measured power generation amounts Eg and exhaust heat recovery amounts Hg, and are calculated from the following formulas 10 and 11.

FIG. 13 shows an example of an arithmetic expression showing the correlation between the power generation amount derived by such a method and the exhaust heat recovery amount. In FIG. 13, the horizontal axis indicates the power generation amount [W], and the vertical axis indicates the exhaust heat recovery amount [W]. The dots indicate the measurement data.
Thereafter, the operation control device 40 proceeds to step 406 to end the processing of this routine, and proceeds the program to step 108 shown in FIG.

Next, in step 108, the operation control device 40 executes the program in accordance with the power generation stop CO ₂ reduction amount calculation routine shown in FIG. 6 and stops power generation in the previously predicted low power consumption time zone. calculating a is the CO ₂ reduction power generation stop CO ₂ reduction Moff.

The operation control device 40 calculates the stop time T (= t2−t1) based on the previously predicted predetermined time zone, that is, the times t1 and t2 (step 502), and the power generation stop of the power generation device 10 is within the stop time T. The time Tstop required for the process, the time Tstart required for the power generation start process for restarting the power generation, and the waiting time Twait (= T−Tstop−Tstart) that is in a standby state between these two times are divided into the CO at each time. _The power reduction CO ₂ reduction amount Moff is calculated by adding the _two reduction amounts using the following formula 12 (step 504).

(Equation 12)
Moff = d1 · Tstop + d2 · Twait + d3 · Tstart

The first term on the right side of Equation 12 is the CO ₂ reduction amount at the time of power generation stop processing, the second term is the CO ₂ reduction amount at the time of standby, and the third term is the CO ₂ reduction amount at the time of power generation restart processing. . In the above formula 12, d1 is a value represented by -C1 · Ef1, d2 is a value represented by -C2 · Ef2, and d3 is represented by C2 · C3 · Hg3-C3 · Ef3-C2 · Hf3. Is the value to be C1 [g / Wh] is the amount of CO ₂ generated per 1 Wh of electricity, and C2 [g / L] is the amount of CO ₂ generated per liter (L) of natural gas, which is the injected fuel. L / W] is a value for unit conversion. Ef [W] is the power consumption consumed by the auxiliary machine for operating the power generation apparatus 10, Hg [W] is the exhaust heat recovery amount, and Hf [L / s] is the fuel input amount. Note that the subscripts 1 to 3 of d, Ef, Hg, and Hf are attached in correspondence with the power generation stop process, the standby time, and the power generation restart process.

  Thereafter, the operation control device 40 proceeds to step 506 to end the processing of this routine, and proceeds the program to step 110 shown in FIG.

Operation controller 40 in step 110, execute the program along the power generation continuation time of CO ₂ reduction amount calculation routine shown in FIG. 7, in the case of continuing power generation in a time zone of low power consumption which is predicted previously CO ₂ A power generation continuation CO ₂ reduction amount Mon, which is a reduction amount, is calculated.

  In step 602, the operation control device 40 calculates the total power generation amount Eg in that time period from the following equation 13 based on the previously predicted predetermined time period, that is, times t 1 and t 2. That is, the area of power consumption from time t1 to time t2 is calculated (integrated) using the power consumption pattern shown in FIG.

  In step 604, the operation control apparatus 40 calculates the total exhaust heat recovery amount Hg in a predetermined time zone based on the total power generation amount Eg calculated in step 602 and the exhaust heat recovery amount characteristic previously learned in step 106. Calculated from Equation 14.

(Equation 14)
Total waste heat recovery amount Hg = a2 Total power generation amount Eg + b2

  Here, a2 and b2 are values derived in step 404 described above.

  In step 606, the operation control apparatus 40 calculates the total fuel input amount Hf in a predetermined time zone based on the total power generation amount Eg calculated in step 602 and the fuel input amount characteristic previously learned in step 104 by the following equation 15 Calculate from

(Equation 15)
Total fuel input Hf = a1 Total power generation Eg + b1

  Here, a1 and b1 are values derived in step 304 described above.

In step 608, the operation control device 40 calculates the power generation continuation CO ₂ reduction amount Mon from the following equation 16 based on the previously calculated total power generation amount Eg, total exhaust heat recovery amount Hg, and total fuel input amount Hf.

(Equation 16)
Mon = C1, Eg + C2, C3, Hg-C2, Hf

Here, C1 [g / Wh] is the amount of CO ₂ generated per 1 Wh of electricity, and C2 [g / L] is the amount of CO ₂ generated per liter (L) of natural gas as the fuel that is input. , C3 [L / W] is a value for unit conversion.

  Thereafter, the operation control device 40 proceeds to step 610 to end the processing of this routine, and proceeds the program to step 112 shown in FIG.

Operation controller 40 in step 112, compared to the power generation stop CO ₂ reduction Moff the continued power generation CO ₂ reduction Mon, power generation stop CO ₂ reduction Moff is whether greater continued power generation CO ₂ reductions Mon judge. The operation control apparatus 40 sets the flag F to 0 when the reduction amount Moff is larger than the reduction amount Mon (step 114), and sets the flag F to 1 when the reduction amount Moff is less than or equal to the reduction amount Mon. Set (step 116). The flag F is a flag indicating the operating state of the power generation apparatus 10 in a predetermined time zone. When the flag F is 0, the operation of the power generation device 10 is a power generation stop operation, and when the flag F is 1, the operation of the power generation device 10 is a continuous power generation operation.

  The operation control device 40 sets the flag F to 0 or 1 in steps 114 and 116, and then advances the program to step 118. In step 118, the program returns to step 102 after waiting for a first predetermined time T1 (for example, 24 hours) to elapse. As a result, the operation control device 40 sets a predetermined time period in advance as described above, and performs a process of determining whether to stop power generation or continue power generation in the predetermined time period for each first predetermined time T1 (for example, Every 24 hours). Note that this processing may be executed periodically at any fixed time of the day.

  Next, the operation control device 40 determines whether the power generator 11 can generate power separately from the process of determining whether to stop power generation or to continue power generation in the predetermined time period described above. 8 is started and the program proceeds to step 702. The operation control device 40 controls the operation of the power generation device 10 by the processing in steps 702 to 708. This operation is executed every second predetermined time T2 (for example, every 60 seconds). The second predetermined time T2 is set to a relatively short time value, and is sufficiently smaller than the first predetermined time described above.

  Specifically, in step 702, the operation control apparatus 40 determines whether or not the current time is a predetermined time zone set in advance. If the current time is a predetermined time zone, the operation control device 40 determines “YES” in step 702 and advances the program to step 704. In step 704, the operation control device 40 determines whether or not the flag F that has been set and stored in advance is 0. If the flag F is 0, the operation control device 40 determines “YES” in step 704, advances the program to step 706, and implements the power generation stop operation of the power generation device 10 in the power generation operation in step 706. To do.

  On the other hand, if the flag F is 1 even if the current time is the predetermined time zone, the operation control device 40 determines “NO” in step 704, advances the program to step 708, and generates power in step 708. The continuous power generation operation of the power generation apparatus 10 in operation is performed. Even when the current time is not in the predetermined time zone, the operation control device 40 determines “NO” in step 702, advances the program to step 708, and performs the continuous power generation operation of the power generation device 10 in step 708.

  The power generation stop operation performed in step 706 will be described in detail along the power generation stop operation routine shown in FIG. In step 802, the operation control device 40 determines whether the current time is any one of the power generation stop processing time Tstop, the power generation restart (startup) time Tstart, or the standby time Twait previously derived in step 502. judge. If the current time is the power generation stop processing time Tstop, the operation control device 40 advances the program to step 804. In step 804, the operation control device 40 performs power generation stop processing for the power generation device 10 during power generation operation. That is, the reformer is stopped, and supply such as combustion is stopped. If the current time is the waiting time Twait, the operation control device 40 advances the program to step 806. In step 806, the operation control device 40 maintains the standby state (power generation stopped state) until the power generation of the power generation device 10 is resumed. If the current time is the power generation resumption (startup) time Tstart, the operation control device 40 advances the program to step 808. In step 808, the operation control device 40 executes a startup process in order to restart the operation of the power generation device 10.

  When the processing of steps 804, 806, and 808 is completed, the operation control device 40 proceeds to step 810, ends the processing of this routine, and proceeds the program to step 710 shown in FIG. In step 710, the program returns to step 702 after waiting for a second predetermined time T2 (for example, 60 seconds) to elapse. Thereby, the operation control apparatus 40 performs the process of step 702-708 for every 2nd predetermined time T2.

  The continuous power generation operation performed in step 708 will be described in detail along the continuous power generation operation routine shown in FIG. The operation control apparatus 40 measures the power consumption of the power usage place 20 using the wattmeter 22 (step 902), and stores the measured power consumption (step 904). Then, the operation control device 40 filters the stored power consumption data (filter processing means: step 906), and compares the processing value filtered by the filter processing means with a predetermined value (comparison means). : Step 908). At this time, if the process value is less than the predetermined value, it is determined as “YES”, it is determined that the first follow-up control can be executed, and the determination signal is set to 0 (step 910). If it is equal to or greater than the value, it is determined as “NO”, it is determined that the first follow-up control cannot be executed, and the determination signal is set to 1 (step 912). The first follow-up control is control in which the output power of the power generation device 10 is made to follow the power consumption, and the first follow-up control can be executed when a change in the power consumption is caused by power generation. That is, the first follow-up control can be executed within the range of the output response performance of the apparatus 10.

  Specifically, in step 906, as the filtering process, only the frequency component of the power consumption that is outside the range of the output response performance of the power generation apparatus 10, that is, the frequency component that cannot be followed by the output power of the power generation apparatus 10 is passed. The low frequency component which 10 output power can track is removed. In other words, the filtering process is executed according to the following equation 17 based on the current data and the stored data for the past several cases (in this embodiment, two cases) or the data for the latest predetermined time.

  U [k] and y [k] are current data, for example, input data and output values (process values) at time k, z is a delay operator, and a0, a1, a2, b0, b1, b2 is a constant.

  As shown in FIG. 14, in areas A1, A2, and A3, when the power consumption greatly and periodically fluctuates beyond the output response performance of the power generation apparatus 10, for example, an electric kotatsu, an electric carpet, an air conditioner, a refrigerator, etc. In the case where the electric appliance to be turned on / off is an external load, when the on / off of the electric appliance is repeated beyond the output response performance of the power generation apparatus 10, the electric appliance fluctuates violently and periodically. The generated power cannot follow the power consumption. However, when such power consumption data is filtered by the above-described step 906, as shown in FIG. 15, the low frequency component is removed and the high frequency component is emphasized. As a result, it is possible to easily compare the processed value after the filter processing with the predetermined value D, and it is possible to reliably and accurately determine the regions A1, A2, and A3 where the generated power cannot follow. Then, when processing is performed in steps 908, 910, and 912, as shown in FIG. 16, when the processing value is less than the predetermined value, it is determined that the first follow-up control can be executed, and the determination signal is set to 0. If the processing value is equal to or greater than the predetermined value, it is determined that the first follow-up control cannot be executed, and the determination signal is set to 1.

  Then, the operation control device 40 executes the first follow-up control when the determination signal is 0 (steps 914 and 916), and differs from the first follow-up control when the determination signal is 1. And the 2nd follow-up control which considered the output response performance of the electric power generating apparatus 10 is performed (step 914,918). Specifically, when the power generation amount is a power consumption that can be followed, the operation control device 40 directly inputs the stored power consumption data and uses the value as the power generation amount instruction value to generate the generator 11. The power generation amount is controlled so as to follow the power consumption measured at the power usage place 20 (step 916). On the other hand, when the power generation amount cannot be followed, the generator 11 is instructed as a power generation amount instruction value by inputting the leveled power consumption data, and the power generation leveled power consumption. Control is performed so as to follow the amount (step 918). Note that the second follow-up control is control for causing the output power to follow the data obtained by attenuating the stored power consumption data (leveled in this embodiment). It is within the range of response performance.

  Therefore, the power generation amount according to the present invention in the case where the power generation amount cannot follow the power generation amount is leveled with the periodically and periodically varying power consumption shown by a thin solid line in FIG. Therefore, control is performed as shown by a thick solid line in FIG. In FIG. 17, the region A1 described above is shown in an enlarged manner. As is clear from FIG. 17, the power generation amount fluctuates so as to take an average value of the power consumption amount. On the other hand, since the power generation amount according to the prior art when the power generation amount cannot be followed is controlled to follow the power consumption amount that fluctuates as much as possible, the power consumption as shown by a thick solid line in FIG. Controlled along the bottom side of consumption. Therefore, according to the present invention, when the power generation amount cannot follow the power generation amount, the power generation amount can be increased as compared with the conventional case, so that the power purchased from the power company can be reduced. In addition, since the vibration of the power generation amount can be suppressed, the amount of preceding fuel input when the power generation amount increases can be suppressed to a low level, thereby reducing the generation of carbon dioxide.

  When the processing of steps 916 and 918 is completed, the operation control device 40 proceeds to step 920, terminates the processing of this routine, and proceeds the program to step 710 shown in FIG. As described above, in step 710, the program returns to step 702 after waiting for a second predetermined time T2 (for example, 60 seconds) to elapse.

As is apparent from the above description, in this embodiment, the power generation stop energy saving effect calculation means (step 108) is one of the energy saving effect indexes when the power generation of the power generation apparatus 10 is stopped in a predetermined time zone. Fuel that is a learning value of the characteristics of the power generation device 10 is calculated by calculating a certain CO ₂ reduction amount and the power generation continuation energy saving effect calculation means (step 110) continues the power generation of the power generation device 10 in a predetermined time zone. Based on the input amount characteristic and the exhaust heat recovery amount characteristic, the comparison means (step 112) compares both energy saving effects respectively calculated by both energy saving effect calculation means, and the switching means (step 704) has a predetermined time. The comparison means determines whether continuous power generation control for continuing power generation of the power generation device 10 or power generation stop control for stopping power generation of the power generation device 10 is performed in the belt. Switch based on the comparison result. Therefore, since it is possible to appropriately switch to an operation having an energy saving effect based on the learned value of the characteristics of the power generation device 10 in a predetermined time zone, even if there is a variation in exhaust heat recovery performance and power generation efficiency for each product, Moreover, even if the exhaust heat recovery amount and power generation efficiency are deteriorated due to secular change, it is possible to provide a cogeneration system that maintains a high energy saving effect without being affected by it.

  Further, since the predetermined time zone is a low power consumption time zone in which the power consumption by the load device 21 is small, the fuel cell cogeneration system originally has a low power generation efficiency when the power generation output amount is small. However, it is possible to carry out efficient driving while maintaining a high energy saving effect.

  The low power consumption time period is a multiplication value Emin × a minimum value Emin of the power consumption pattern of the day derived from the power consumption data measured and stored in advance and multiplied by a predetermined value C. Since it is the time zone of the power consumption pattern in which the power consumption is smaller than C, the low power consumption time zone can be appropriately derived according to the actual power consumption pattern.

  Further, the characteristics of the power generation device 10 are a power generation amount-fuel input amount characteristic which is a correlation between the power generation amount of the power generation device 10 and the fuel input amount input to the power generation device 10, and the power generation amount of the power generation device 10 and the hot water storage tank. The power generation amount-exhaust heat recovery amount characteristic, which is a correlation with the exhaust heat recovery amount recovered at 30, can improve the energy saving effect more reliably.

In the above-described embodiment, the predetermined time period in which the switching between the continuous power generation control for continuing the power generation of the power generation apparatus 10 or the power generation stop control for stopping the power generation of the power generation apparatus 10 is performed is performed. Although it is set as a low power consumption time zone, it may be set as an arbitrary time zone regardless of the power consumption. For example, the time may be set simply (for example, between 7:00 and 9:00). Also in this case, the CO ₂ reduction amount when the operation of the power generation apparatus 10 is stopped is compared with the case where the power generation is continued, and the operation with the larger CO ₂ reduction amount is selected and executed in a predetermined time zone. do it. Also, in this case, when the power generation stop process is to be performed when the power generation device 10 generates relatively high power during a predetermined time period, the power generation is stopped despite the high power demand. It is preferable to warn that.

In the above-described embodiment, the CO ₂ reduction amount is increased as an index of the energy saving effect. However, other indexes (for example, energy reduction amount, household utility cost) may be adopted.

  Further, as the power generation device 10, there is a power generation device 11 in which the power generator 11 generates AC power and directly outputs it without going through the exchanger 12.

It is a schematic diagram showing an outline of one embodiment of a cogeneration system according to the present invention. It is a flowchart of the control program performed with the operation control apparatus shown in FIG. 3 is a flowchart of a low power consumption time zone prediction routine executed by the operation control device shown in FIG. 1. 3 is a flowchart of a fuel injection amount characteristic learning routine that is executed by the operation control apparatus shown in FIG. 1. 3 is a flowchart of an exhaust heat recovery amount characteristic learning routine executed by the operation control apparatus shown in FIG. ₂ is a flowchart of a power generation stop CO ₂ reduction amount calculation routine executed by the operation control device shown in FIG. FIG. 3 is a flowchart of a CO ₂ reduction amount calculation routine for continued power generation that is executed by the operation control device shown in FIG. It is a flowchart of the control program performed with the operation control apparatus shown in FIG. It is a flowchart of the electric power generation stop operation routine performed with the operation control apparatus shown in FIG. It is a flowchart of the continuous electric power generation operation routine performed with the operation control apparatus shown in FIG. It is a graph which shows an example of a power consumption pattern and a predetermined time slot | zone. It is a graph which shows an example of the learning result of the fuel injection quantity characteristic of a power generator. It is a graph which shows an example of the learning result of the waste heat recovery amount characteristic of a power generator. It is a graph which shows the power consumption which fluctuates | varies intensely periodically processed by the process of a continuous electric power generation operation routine. 15 is a graph obtained by filtering the power consumption shown in FIG. 14 according to the present invention. It is a graph which shows the signal of whether the electric power generation amount can track electric power consumption using the graph shown in FIG. It is a graph which shows the electric power consumption and electric power generation which are fluctuate | varied violently periodically processed by the process of a continuous electric power generation operation routine. 6 is a graph showing intense and periodically varying power consumption and power generation processed by the prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Power generation device, 10a ... Wattmeter, 11 ... Generator, 12 ... Converter, 13 ... Fuel supply device, 13a ... Flow meter, 14 ... Water supply device, 15 ... Transmission line, 16 ... System power supply, 21 ... Load Apparatus, 26a ... Hot water use device, 26b ... Heat use device, 30 ... Hot water storage tank, 34 ... Temperature sensor group, 36 ... Flow rate sensor, 40 ... Operation control device.

Claims (4)

A power generator for supplying power to the load device;
An operation control device for controlling the power generation device so as to have a power generation amount corresponding to a power generation amount instruction value;
A hot water storage tank for storing hot water recovered from the exhaust heat of the power generation device;
In the cogeneration system with
A power generation stop energy saving effect calculating means for calculating an energy saving effect when power generation of the power generation device is stopped in a predetermined time zone;
A power generation continuation energy saving effect calculating means for calculating an energy saving effect when the power generation of the power generation device is continued in the predetermined time zone based on a learned value of the characteristics of the power generation device;
Comparing means for comparing the energy saving effects calculated by the energy saving effect calculating means;
Switching means for switching whether to perform continuous power generation control to continue power generation of the power generation device or to perform power generation stop control to stop power generation of the power generation device in the predetermined time zone based on the comparison result by the comparison means A cogeneration system characterized by comprising   2. The cogeneration system according to claim 1, wherein the predetermined time zone is a low power consumption time zone in which the power consumption by the load device is small.   3. The low power consumption time zone according to claim 2, wherein the low power consumption time zone is a multiplication obtained by multiplying a minimum value of power consumption in a daily power consumption pattern derived from the power consumption data measured and stored in advance by a predetermined value. A cogeneration system characterized in that it is a time zone of the power consumption pattern in which the power consumption is smaller than the value.   4. The power generation amount-fuel input amount according to any one of claims 1 to 3, wherein the characteristic of the power generation device is a correlation between a power generation amount of the power generation device and a fuel input amount input to the power generation device. A power generation amount-waste heat recovery amount characteristic that is a correlation between the characteristics and the power generation amount of the power generation device and the heat recovery amount recovered in the hot water storage tank.

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