JP2006127967A - Cogeneration system and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operating method of a cogeneration system in which electric power demand and heat demand are predicted and in which repetition of starting and stopping of a power generation device is suppressed based on the prediction, and provide a cogeneration system in which the repetition of the starting and stopping is suppressed. <P>SOLUTION: This is the operation method of the cogeneration system provided with the power generation device to generate electric power and to generate heat, and a heat storing part to store the generated heat, and this is provided with a process St 30 of predicting the electric power demand over a prescribed time, a process St 40 of predicting the heat demand over a prescribed time, a process of inputting a time period when starting of the power generation device is not allowed by an input means, and a process St 80 of controlling the starting and stopping of the power generation device based on the predicted electric power demand and heat demand, as well as the time period when the starting is not allowed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an operation method of a cogeneration system that uses generated power of an electric power generation apparatus and its exhaust heat, and more particularly, to an operation method that responds to electric power demand and heat demand and suppresses unnecessary start / stop.

  Cogeneration systems that generate power and use the exhaust heat generated during power generation as a heat source have high fuel efficiency, and are therefore widely used for business use, housing complexes, and home use. It also supplies hydrogen-rich fuel gas reformed from raw material fuel such as city gas, LPG (Liquid Petroleum Gas), digestion gas, methanol, GTL (Gas To Liquid) and kerosene, and contains oxygen such as air A fuel cell that generates electricity by an electrochemical reaction with an oxidant gas has attracted attention because its exhaust gas is clean.

  It is preferable that the exhaust heat from the power generation device is stored as hot water because the device is simple. That is, the cooling medium for cooling the power generation apparatus is directly used as hot water, or hot water heated by exchanging heat with the cooling medium is stored in a hot water storage tank, and the hot water is supplied according to the heat demand.

  In a power generation device such as a fuel cell, power generation efficiency is extremely reduced when the amount of power generation is below a certain level. Therefore, it is common to stop the power generator when the power demand falls below a predetermined value. In a fuel cell, it takes time to start in order to raise the fuel cell to a temperature suitable for an electrochemical reaction and to obtain a fuel gas from a raw material fuel. For this reason, it is not an appropriate operation method to repeatedly start and stop according to fluctuations in power demand throughout the day, and repeated start and stop adversely affects the structure of the fuel cell, resulting in a long service life. There is a risk of shrinking. In addition, when power generation is performed according to electric power demand, the amount of heat stored in the hot water storage tank becomes full, and it may become impossible to absorb exhaust heat more than that. If the exhaust heat cannot be absorbed, the power generator cannot be cooled, and the operation of the power generator must be stopped.

  Accordingly, the present invention provides a cogeneration system operation method that predicts power demand and heat demand and suppresses repeated start and stop of a power generation device based on the prediction, and a cogeneration system that suppresses repeated start and stop The purpose is to do.

  In order to achieve the above object, an operation method of a cogeneration system according to the first aspect of the present invention includes, as shown in FIGS. 1 and 2, for example, a power generation apparatus 10 that generates power and generates heat, as shown in FIGS. The operation method of the cogeneration system 100 including the heat storage unit 20 that stores the generated heat; step St30 for predicting power demand over a predetermined time; step St40 for predicting heat demand over a predetermined time; Step St10 of inputting a time zone in which the start is not permitted by the input means 61; Step St80 of controlling the start and stop of the power generation apparatus 10 based on the predicted power demand and heat demand, and the time zone in which the start is not permitted. With.

  With this configuration, since a time zone during which start is not permitted is input, the number of start / stop times of the power generation device can be suppressed and maintenance of the life of the power generation device can be maintained as compared to an operation in which start / stop is performed based on predicted demand. Thus, it is possible to reliably prevent a decrease accompanying the start of fuel efficiency, which is the amount of power generation relative to the consumption of raw material fuel. In addition, since the time zone during which activation is not permitted is input, the control of operation is simplified.

  Moreover, the operation method of the cogeneration system which concerns on invention of Claim 2 is forcing the electric power generating apparatus 10 in the operation method of Cogeneration system of Claim 1 as shown, for example in FIG.1 and FIG.2. A step St20 for setting the start time of the power generation device; a step St80 for controlling the start and stop of the power generation device forcing the predicted power demand, the heat demand and the time zone during which the start is not permitted, and the power generation device 10 to force The start and stop of the power generation device 10 are controlled based on the start time.

  If comprised in this way, since a power generator is forcibly started, it becomes the operation method of the cogeneration system which can satisfy | fill heat demand reliably irrespective of electric power demand.

  Further, the operation method of the cogeneration system according to the invention of claim 3 is, for example, as shown in FIG. 2, when a power demand of a predetermined amount or more is predicted continuously for a predetermined time or more (St50), The power generation device is activated by canceling the time zone during which activation is not permitted (St60).

  If comprised in this way, since the time slot | zone which does not permit starting is cancelled | released and a power generator is started, a power generator can be operated in the time slot | zone with a large electric power demand, and the efficiency of a power generator will become high. That is, the efficiency of the cogeneration system can be increased.

  In addition, the cogeneration system according to the invention of claim 4 includes, for example, as shown in FIG. 1, a power generation device 10 that generates power and generates heat; a heat storage unit 20 that stores the generated heat; Power demand predicting means 51 for predicting heat demand; heat demand predicting means 52 for predicting heat demand; start-up non-permitted time zone input means 61 for inputting a start-up non-permitted time zone that does not permit the start-up of the power generation apparatus 10; A minimum operating power storage means 55 for storing power; a time measuring means 54 for measuring time; a power demand predicted by the power demand prediction means when the time measured by the time measuring means 54 is not a start-up non-permitted time zone Is provided with the starting control means 53 which starts the electric power generating apparatus 10, if it is more than operation minimum electric power.

  With this configuration, since a time zone during which start is not permitted is input, the number of start / stop times of the power generation device can be suppressed and maintenance of the life of the power generation device can be maintained as compared to an operation in which start / stop is performed based on predicted demand. Thus, it is possible to reliably prevent a decrease in fuel efficiency due to startup. In addition, since the time zone during which activation is not permitted is input, the control of operation is simplified.

  In addition, the cogeneration system according to the invention described in claim 5 is a fuel cell that generates power using hydrogen as fuel in the cogeneration system 100 according to claim 4, for example, as shown in FIG. is there.

  With this configuration, in a cogeneration system using a fuel cell that requires a lead time for startup as a power generation device, the number of startups and stops is suppressed, so that the reduction in fuel efficiency associated with startup becomes significant.

  According to the present invention, since the time zone in which activation is not permitted is input, the number of activation / deactivation of the power generation device is suppressed and maintenance of the life of the power generation device is maintained as compared with the operation in which activation / deactivation is performed based on the predicted demand. A cogeneration system that can reliably prevent a decrease in fuel efficiency associated with startup, or an operation method thereof, is provided. In addition, a cogeneration system with simplified operation control or an operation method thereof is provided for inputting a time zone during which activation is not permitted.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or equivalent devices are denoted by the same reference numerals, and redundant description is omitted.

  First, the configuration of a cogeneration system 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram showing a configuration of a cogeneration system 100 according to an embodiment of the present invention. The cogeneration system 100 includes a fuel cell 10 as a power generator, a hot water storage tank 20 as a heat storage unit that stores heat generated in the fuel cell 10, and heat exchange between cooling water of the fuel cell 10 and hot water of the hot water storage tank 20. And a control device 50 for controlling the operation of the cogeneration system 100. A broken line connecting the fuel cell 10 and the hot water storage tank 20 to each means in the control device 50 indicates that signals are exchanged between them, although details are omitted in the following description. The device that exchanges signals with the control device 50 is not limited to the fuel cell 10 and the hot water storage tank 20, and other devices also exchange signals, but the broken lines are omitted.

  The fuel cell 10 includes a cooling water pipe 11 through which cooling water flows to cool the fuel cell, that is, recovers heat generated in the fuel cell, a fuel gas pipe 12 that supplies a fuel gas rich in hydrogen, and oxygen. The oxidant gas pipe 13 for supplying the oxidant gas to be connected is connected. The cooling water pipe 11 is connected to the heat exchanger 30. The fuel gas pipe 12 may be connected to a fuel gas tank (not shown) that stores fuel gas, or may be connected to a reformer (not shown) that reforms city gas or the like into fuel gas. The oxidant gas pipe 13 may be connected to a blower (not shown) for supplying air, or may be connected to another oxygen-containing gas source. The above fuel gas tank, reformer, blower, gas source, and the like are also included in the elements constituting the cogeneration system 100.

  A hot water circulation pipe 21 and a hot water supply pipe 22 are connected to the hot water storage tank 20. The hot water circulation pipe 21 is connected to the heat exchanger 30. The hot water supply pipe 22 is connected to heat demand (not shown). Here, the heat demand may be one that consumes the supplied hot water or one that consumes only the heat held by the hot water. The heat demand is, for example, hot water consumption at home or a heating appliance. The hot water storage tank 20 is provided with a thermometer for measuring the temperature of hot water, more precisely, a temperature distribution, and a water level meter for measuring the amount of hot water, and the hot water supply pipe 22 is supplied with hot water such as flow rate and temperature. Measuring instruments for measuring quantities are provided. These measuring instruments (not shown) are also included in the elements constituting the hot water storage tank 20. The hot water storage tank 20 is further connected with a hot water return pipe (not shown) for returning the hot water supplied to the heat demand from the heat demand to the hot water storage tank 20 and a replenishment water pipe (not shown) for replenishing a decrease due to consumption of the hot water. May be.

  The heat exchanger 30 is a device that performs heat exchange between the cooling water that cools the fuel cell 10 and the hot water stored in the hot water storage tank 20 and supplied to the heat demand. That is, the cooling water is cooled and the hot water is heated. Be warmed. The heat exchanger 30 may be a multi-tubular heat exchanger, a plate heat exchanger, or another type of heat exchanger.

  By cooling the cooling water that cools the fuel cell 10 with the hot water stored in the hot water storage tank 20 in this way, that is, by warming the hot water with the cooling water, the exhaust heat of the fuel cell 10 is used as the hot water storage tank 10. Can store heat. However, as the heat storage in the hot water storage tank 20 proceeds, the temperature of the hot water rises and the hot water can no longer cool the cooling water. The fact that the cooling water cannot be cooled means that the fuel cell 10 cannot be cooled, and if the fuel cell 10 is operated further, the temperature of the fuel cell 10 rises excessively, so the fuel cell 10 must be stopped. You won't get. Such a state is a state in which the heat storage in the hot water storage tank 20 is full. When the heat storage is full, the cooling water of the fuel cell 10 may be cooled by other cooling means such as an air cooling device or another cooling medium. If comprised in this way, a cogeneration system can be drive | operated without considering full of heat storage.

  The control device 50 is connected to the fuel cell 10, the hot water storage tank 20, the heat exchanger 30, or measuring instruments and control valves of each pipe through a signal cable, receives state quantities such as temperature, pressure, flow rate, etc. The operation of the cogeneration system 100 is controlled by transmitting an operation instruction signal to the device. The control device 50 includes a power demand prediction unit 51, a heat demand prediction unit 52, a start control unit 53, a time measuring unit 54, a storage unit 55, a start non-permitted time zone setting unit 56, a forced start time setting unit 57, and a stop control unit. 58, a fuel cell output control means 59, a start non-permission time zone input means 61, and the like. Specifically, the power predicting means 51, the heat demand predicting means 52 and the start control means 53, the start non-permitted time zone setting means 56, the forced start time setting means 57, the stop control means 58 and the output control means 59 are a CPU. Is realized by executing a computer program stored in the storage means 55 in advance, and the timing means 54 is generally a chronometer and the storage means 55 is generally a memory. Further, the activation non-permission time zone input means 61 may be an input key or a keyboard integrated with the remote controller or the control device 50. By using the activation non-permission time zone input means 61 as a remote controller, it is possible to input the activation non-permission time zone while staying in the living room, for example, wherever the cogeneration system is installed. Further, if the start non-permitted time zone input means 61 is an input key integrated with the control device 50, the control device itself has a simple configuration, can prevent malfunction due to noise, and has high reliability. If the startup non-permission time zone input means 61 is a keyboard, the key operation is further facilitated and erroneous input can be prevented. Although typical data transmission in the control device 50 is indicated by a solid line in FIG. 1, data transmission (not shown) is also performed.

  The fuel cell 10 is connected with a power cable 16 for supplying the generated power to the power demand. The electric power demand is, for example, electric appliances at home, or electric power may be supplied to an electric power company. Since the power generated by a fuel cell is generally direct current, a converter (not shown) that converts it into alternating current power is provided, and measurement that measures voltage, current, frequency, power supplied to power demand, etc. Equipment (not shown) is provided as needed. Further, when a plurality of power demands are provided, a switchboard (not shown) is also provided. These converters, measuring instruments, switchboards, and the like are also included in the elements constituting the cogeneration system 100.

  Then, with reference to FIG. 2, the control of the driving | operation of the cogeneration system 100 shown in FIG. 1 is demonstrated. For the apparatus of the cogeneration system 100, refer to FIG. FIG. 2 is a flowchart showing control of operation of the cogeneration system 100.

  Control of the operation of the cogeneration system 100 is basically performed on a daily basis. For example, in a daily life cycle at home, electricity demand and heat demand are repeated, so even if electricity demand and heat demand are in apartment houses, offices or factories, etc. Repeated. For example, when the electric power demand or the heat demand is repeated not for one day but for one week, for example, as a minimum unit, it may be performed in units of one week or in other units.

  At the beginning of the operation of the cogeneration system, a start non-permission time zone in which start of the power generation apparatus 10 is not permitted is input from the start non-permission time zone input means 61 (St10). The start-up disapproval time zone is generally low in power demand, and even when the fuel cell 10 is operating, the amount of power generation is low and the power generation efficiency is low. This is a time period during which the battery is not activated. This start-up disapproval time zone is determined empirically and based on past driving performance.

  FIG. 3 shows a graph of an example of fluctuation in power consumption per day of a general household, that is, power demand. The horizontal axis represents the time of the day, and the vertical axis represents the power demand. Power demand increases between 6:00 am and 7:00 am and between 8:00 am and 9:00 am, but generally the power demand from 16:00 in the evening is low, and the power demand in the time zone from 16:00 to around 23:00 is high. Can be seen. In general, the power generation device is manufactured so that the power generation efficiency is the highest at the output near the rated power generation amount, and the operation at the output lower than the rated power generation amount deteriorates the power generation efficiency. For example, in a fuel cell with a rated power generation for household use of 1 kW, operation at an output of 300 W or less because the power generation efficiency drops sharply when operated at an output of 300 W or less, and the heat balance as a power generator is lost. Is not suitable. That is, in this case, 300 W is a threshold value for power demand for operating the fuel cell.

  Further, in general, in a fuel cell, in order to reform a fuel gas from a raw material fuel such as kerosene to generate power from a stopped state, the fuel cell, the fuel gas, and the fuel cell In order to heat the oxidant gas to a predetermined temperature, a lead time of about 1 hour is required. Therefore, even if an increase in power demand is recognized in the morning as shown in FIG. 3, there is no merit of starting the fuel cell for a 2-hour operation, considering a lead time of 1 hour. Therefore, when the power demand is as shown in FIG. 3, one cycle may be set from 0 o'clock to 24 o'clock, for example, from 0 o'clock to 15 o'clock may be set as a start non-permitted time zone.

  Since the power demand changes based on various factors such as season, day of the week, temperature, weather, and family structure, it is preferable to change the start-up disapproval time zone as appropriate, and the user inputs it. That is, when the user inputs appropriately, one cogeneration system 100 can be appropriately and efficiently operated. However, since it takes too much time to input every day, if the activation disapproval time zone may be the same as the previous day, the input is omitted and the activation disapproval time zone of the previous day stored in the storage means 55 of the control device 50 is set. It is preferable to use it. In other words, the storage means 55 stores at least the latest startup non-permission time zone. As will be described later, in order to ensure the function of automatically checking and changing the startup disapproval time zone, the start disapproval time zone for 3 days is stored, preferably the start disapproval time for one week. A zone is stored, more preferably, a startup non-permission time zone for one month is stored, and a startup non-permission time zone for one year is more preferably stored.

  Returning to FIG. 2, the description of the control of the operation of the cogeneration system 100 will be continued. At the beginning of the operation of the cogeneration system, a forced start time, which is a time for forcibly starting the power generation apparatus 10, is input (St20). The means for inputting the forced start time is also suitable for use as the start non-permitted time zone input means 61 because it simplifies the configuration, but in order to prevent erroneous operation, the start non-permitted time zone input means 61 and May include different forced activation time input means.

  The forced activation time is a time for activating the fuel cell so that the fuel cell 10 generates heat necessary for storing a predetermined amount of hot water of a predetermined temperature or higher in the hot water storage tank 20 to satisfy the heat demand. is there. That is, it is the time at which the fuel cell 10 must be activated to meet the heat demand regardless of the power demand.

  FIG. 4 shows a graph of a variation example of heat demand per day of a general household. The horizontal axis represents the time of the day, and the vertical axis represents the heat demand. Here, the heat demand is a hot water supply load, that is, consumption of hot water. Although an increase in hot water supply load is observed between 8:00 and 9:00 in the morning, it can be seen that the hot water supply load in the time zone from 18:00 to 21:00 is high.

  FIG. 5 shows a graph of fluctuation in average hot water supply load per hour in the fluctuation example of hot water supply load shown in FIG. The horizontal axis represents the time of the day, and the vertical axis represents the average of the hot water supply load per hour. FIG. 5 clearly shows that the hot water supply load between 18:00 and 21:00 is high.

  Therefore, it is necessary to store hot water in the hot water storage tank 20 in preparation for a hot water supply load from 18:00 to 21:00. The hot water absorbs the heat generated in the fuel cell 10 with the cooling water, and the hot water is heated by transferring the heat from the cooling water in the heat exchanger 30. Therefore, it is necessary to operate the fuel cell 10 in order to ensure hot water at a predetermined temperature or higher. From the integrated value of the hot water supply load, that is, the required hot water supply amount and the required time, the time at which the operation of the fuel cell 10 must be started, that is, the forced start time is determined. Here, when the user inputs the forced activation time, a predetermined hot water supply amount is surely prepared at a predetermined time. As will be described later, the forced activation time may be set by calculating in the control device 50 based on the predicted heat demand, and the user may not input. With this configuration, the user's input is saved, and abnormal operation due to erroneous input or forgotten input can be prevented.

  Since the hot water supply load changes based on various factors such as season, day of the week, temperature, weather, and family structure, the forced activation time is preferably changed as appropriate, and is input by the user. That is, when the user inputs appropriately, one cogeneration system 100 can be appropriately and efficiently operated. However, since it takes too much time to input every day, when the forced activation time may be the same as the previous day, the input is omitted and the forced activation time of the previous day stored in the storage means 55 of the control device 50 is used. It is preferable. That is, the storage means 55 stores at least the latest forced activation time. As will be described later, in order to ensure the function of automatically checking and changing the forced start time, the forced start time for three days is stored, preferably the forced start time for one week is stored, Preferably, the forced start time for one year is stored.

  Returning to FIG. 2, the description of the control of the operation of the cogeneration system 100 will be continued. The power demand at a certain time is predicted (St30). The prediction of power demand predicts the power demand from that time to a predetermined time ahead. The predetermined time is preferably a minimum cycle in which the power demand is repeated, and in this embodiment, it is one day, that is, 24 hours. The predicted power demand is the power demand for each time. The time interval to be predicted is, for example, about every 10 minutes from 1 minute, and is suitable for 24 hour power demand prediction. Predicting in too fine time increments increases the effort and amount of data to be predicted, but fluctuations in power demand in fine time increments are substantially meaningless, and the operation of the cogeneration system 100 is Since it does not follow the minute fluctuations, the waste increases. On the other hand, if the prediction is performed with a time step that is too coarse, fluctuations in power demand may not be appropriately reflected in the operation of the cogeneration system 100.

  Electric power demand can be predicted by various methods. For example, a large amount of electricity demand data corresponding to various factors such as season, day of the week, temperature, weather, family composition or power demand at that time is prepared, and so-called case-based reasoning can be used to calculate power demand under the closest conditions. It is also possible to use a method of guiding and correcting by differences in various factors. In this method, the accuracy of prediction is greatly influenced by the amount of power demand data that is aligned with the types of factors to be considered, but by storing the power demand data every time it is operated, a learning function can be easily provided. . Alternatively, the power demand may be obtained by multivariate analysis of past power demand data according to various factors such as season, day of the week, temperature, weather, and family composition. The prediction of power demand may be performed by other known methods.

  The power demand prediction is performed by the power demand prediction means 51 of the control device 50. Typically, the power demand prediction unit 51 is a computer program, but may include dedicated hardware such as a neural network.

  Here, factors such as season, day of the week, temperature, and weather may be input by the user, but may be obtained through the Internet or the like in order to reduce the user's work, and measured by the cogeneration system 100. You may have equipment, measure temperature, humidity, wind power, etc., and also have a calendar function to determine various factors. Further, as the power demand at that time, it is preferable to use a value measured by a power meter provided in the power cable 16 for measuring the power supplied to the power demand. However, the family structure and the like are preferably input by the user and stored and stored in the storage means 55 of the control device 50.

  Subsequently, in the operation of the cogeneration system 100, the heat demand at a certain time is predicted (St40). The prediction of heat demand predicts the heat demand up to a predetermined time in the same manner as the prediction of power demand. Generally, the predetermined time for predicting power demand and the predetermined time for predicting heat demand are the same, but they are not necessarily the same and may be different. Since the operation of the fuel cell 10 to satisfy the heat demand is at a point in time that goes back from the time of the heat demand, the heat demand may be predicted to a point before the power demand. The heat demand prediction method can be performed using the same method as the power demand prediction method. If the method for predicting heat demand is the same as the method for predicting power demand, the controller 50 can be simplified, for example, it can also be used as a computer program, but it may be predicted by a different method. The prediction of heat demand is performed by the heat demand prediction means 52 of the control device 50. That is, the power demand prediction means 51 and the heat demand prediction means 52 may have a shared part. In addition, the factors used for predicting heat demand are often the same as the factors used for predicting power demand, and the factors can also be shared.

  When the power demand and heat demand are predicted, the operation mode is reviewed. First, the time when the predicted power demand exceeds the output threshold value for operating the fuel cell 10 is checked to check whether the time continues for a predetermined time (St50). Here, the predetermined time is a time when the fuel cell 10 is operated more efficiently even when the time for starting the fuel cell 10 is taken into consideration. For example, in a fuel cell with a rated power generation for household use of 1 kW, even if it takes 1 hour to start up, if the efficiency is improved after operating for 3 hours, the predetermined time is 3 hours. In addition, even if there is a moment when the power demand falls below the threshold for the duration to continue for a predetermined time, it may be a time that exceeds the threshold if averaged, or there is a moment when the power demand falls below the threshold May be excluded. Which is suitable depends on, for example, the degree of the problem of the fuel cell 10 when operating at an output below the threshold, or the surplus power processing method when the operation is continued above the threshold. Even if the fuel cell 10 is operated at an output lower than the threshold value, the power generation efficiency only deteriorates and there is no problem as a device, or when surplus power can be reversely flowed to the power system of the electric power company or with surplus power, for example, a hot water storage tank If measures such as heating can be taken, it would be more appropriate to start even if there is a moment when the power demand falls below the threshold, and in the opposite case it would be better not to start Will. The operation of checking the time when the predicted power demand exceeds the output threshold value for operating the fuel cell 10 and checking whether the time continues for a predetermined time is as follows: Done.

  When the predicted power demand exceeds the output threshold value for operating the fuel cell 10 continues for a predetermined time, the startup non-permission time zone is canceled (St60). Here, it is preferable to start the fuel cell 10 earlier by the lead time than the predicted power demand starts to exceed the threshold value so that the fuel cell 10 outputs when the power demand increases. That is, more specifically, the time for canceling the start-up non-permission period is from the lead time before the predicted power demand exceeds the threshold. The work for canceling the non-permission time zone is performed by the startup non-permission time zone setting means 56. Alternatively, the activation control unit 53 may perform this.

  Subsequently, the forced start time is reset based on the predicted heat demand (St70). As described above, in order to satisfy the heat demand, the fuel cell 10 is operated regardless of the power demand. However, the fuel cell 10 must be started in time for the heat demand time. Therefore, the time for starting the fuel cell 10 is calculated from the predicted heat demand.

  The operation procedure for resetting the forced start time is specifically shown in the flowchart of FIG. First, the total heat demand from the time when resetting to the time when heat demand ends is calculated (St71). For example, in the hot water supply load shown in FIG. It is preferable to calculate not only the total heat demand up to the time when the heat demand ends but also the integrated value of the heat demand up to each time up to that time, because a more detailed forced start time can be set as will be described later. .

  Next, the amount of heat stored in the hot water storage tank 20 at that time is calculated (St72). The amount of heat stored is calculated from the temperature distribution of the hot water stored in the hot water storage tank 20 and the amount of stored water, and the temperature distribution of the hot water and the amount of stored water are based on the measured values by measuring instruments installed in the hot water storage tank 20. That is, the hot water storage tank 20 is provided with an instrumentation cable for transmitting those measuring instruments and measurement values to the control device 50.

  A necessary calorific value is calculated as a difference between the total heat demand and the amount of heat stored (St73). In calculating the required heat generation amount, it is preferable to consider a loss such as heat dissipation from the hot water storage tank 20.

  Subsequently, based on the predicted power demand, a calorific value that generates heat by the time when the heat demand is terminated by the operation of the fuel cell 10 (that is, when the necessary calorific value is necessary) is calculated (St74). However, not all the heat generated by the operation of the fuel cell 10 is stored as hot water in the hot water storage tank 10, so the heat exchange efficiency in the heat exchanger 30 or the cooling water pipe 11 and the hot water circulation pipe 21 It is preferable to consider loss due to heat dissipation. Also, if you calculate not only the amount of heat generated up to the time when the heat demand ends but also the integrated value of the amount of heat generated up to each time up to that time, you can set the detailed forced start time as described later. preferable.

  When the calorific value due to the operation of the fuel cell 10 exceeds or equals the required calorific value, the heat demand is satisfied by the heat generated by the operation of the fuel cell 10 based on the electric power demand. It becomes unnecessary, and the resetting of the forced activation time is not performed (St75). That is, the forced activation time is canceled. When the calorific value due to the operation of the fuel cell 10 is less than the required calorific value, the process proceeds to the next step. Note that the comparison between the calorific value and the required calorific value is not a single point until the end of heat demand, but is performed at each time until the end of heat demand. Therefore, more reliable operation can be performed, which is preferable.

  Next, the amount of heat generated when the rated operation is performed regardless of the power demand is calculated at the time when the predicted power demand exceeds the threshold and the operation of the fuel cell 10 is predicted (St76). That is, it is assumed that the fuel cell 10 operates only at high power generation efficiency because it has the highest power generation efficiency when operated at the rated output. In this case, the power generated in excess of the power demand may flow backward to the power system of the power company, or the hot water storage tank 20 may be heated with the surplus power, for example. Heating with surplus power has the same effect as increasing the amount of heat generation, and the amount can be added to the amount of heat generation. In order to heat the hot water storage tank 20, it is preferable to provide the hot water storage tank 20 with an electric heater and supply surplus power to the electric heater. Calculation of the amount of heat generated by operation at this rated output may be omitted.

  If the calorific value at the rated operation exceeds or equals the required calorific value, the heat demand is satisfied by the heat generated by the operation at the rated output of the fuel cell 10 based on the electric power demand, so forced start-up The time setting is not required, and the forced start time is not reset (St77). That is, the forced activation time is canceled. If the amount of heat generated by operation of the fuel cell 10 at the rated output is less than the required amount of heat, the process proceeds to the next step. It should be noted that the comparison between the calorific value at the rated operation and the required calorific value is not at one point until the end of the heat demand, but at each time until the end of the heat demand. Since there is no time zone where there is a shortage, it is possible to perform more reliable operation, which is preferable.

  When the operation of the fuel cell 10 based on the electric power demand cannot satisfy the heat demand, the forced activation time is reset (St78). That is, the time for starting the fuel cell 10 to satisfy the heat demand is calculated. For example, the time is calculated by dividing the difference between the required calorific value and the calorific value by the calorific value per hour when the fuel cell 10 is operated. Therefore, the time may be traced back from the time when the heat demand ends. The operation of the fuel cell 10 at this time is assumed to operate at an output that fluctuates based on electric power demand or to operate at a rated output. In any case, be consistent with actual operation. The above-described forced activation time resetting (St70 or St71 to 78) is performed by the forced activation time setting means 57 of the control device 50.

  Here, by comparing and analyzing the difference between the input forced start time and the forced start time calculated as described above, it is possible to determine whether the power demand and the heat demand are unique. Note that this analysis is performed after a continuous operation is performed instead of a single operation, and a large number of comparisons of the difference between the input forced start time and the calculated forced start time are collected to withstand the analysis. If it is a peculiar power demand or heat demand, it is preferable to reflect it in the input of the subsequent forced start time. In this way, by setting the forced startup time to be a time that matches the power demand and heat demand, whether the difference between the prediction of power demand and heat demand and the actual demand is abrupt or always deviates. It is easy to determine whether or not the power is present, which can contribute to the improvement of the prediction accuracy of the power demand and the heat demand. Therefore, maintenance becomes easy.

  Returning to FIG. 2, the description of the control of the operation of the cogeneration system 100 will be continued. When the forced activation time is calculated and reset, the operation of the fuel cell 10 is controlled (St80). Operation control of the fuel cell 10 can be broadly divided into starting the fuel cell 10, stopping the fuel cell 10, and adjusting the output of the fuel cell 10.

  FIG. 7 shows a flowchart for explaining start-up control of the fuel cell 10. In starting control of the fuel cell 10, first, the time is recognized by the time measuring means 54 (St81). Then, it is determined whether the predicted power demand value at the time or after a predetermined time corresponding to the lead time is equal to or greater than the power demand threshold determined by the fuel cell 10 (St82). If the predicted power demand value is greater than or equal to the power demand threshold value, it is determined whether or not the time is in the startup non-permitted time zone (St83). Note that, contrary to the above order, after determining whether it is the startup non-permission time zone, it may be determined whether the predicted power demand is equal to or greater than a threshold value. If the predicted power demand is equal to or greater than the threshold value and is not in the startup non-permitted time zone, the fuel cell 10 is started (St85). At other times, the fuel cell 10 is not started. However, it is determined whether the time corresponds to the forced start time (St84), and when it corresponds, the fuel cell 10 is started (St85). Activation control of the fuel cell 10 is performed by the activation control means 53 of the control device 50.

  When the fuel cell 10 is activated by the above control, the fuel cell 10 is not activated during the activation disapproval time period. Therefore, the fuel cell 10 is not activated in the time period when the power demand is low, and the fuel cell 10 is frequently started and stopped. Will not be done. Therefore, it is possible to prevent damage to the device or a reduction in the service life due to repeated start / stop. In addition, since the operation at an output considerably lower than the rated output can be reduced, the power generation efficiency is increased. Furthermore, in order to start up, preparation work for starting is performed during the lead time during which power generation is not performed, and raw material fuel and the like are consumed accordingly. In other words, the power generation amount with respect to the overall consumption of the raw material fuel is reduced when the system is started up. Therefore, by suppressing frequent start / stop, it is possible to prevent the fuel efficiency from being lowered due to the start, and to increase the fuel efficiency as a result. Further, since the fuel cell 10 is not operated during a time period when the power demand is low, the exhaust heat from the fuel cell 10 is not stored during that time, and the amount of heat stored in the hot water storage tank 20 becomes full when the power demand increases. The fuel cell 10 must be stopped.

  Further, since the forced start time is set and the fuel cell 10 is started regardless of the power demand at the forced start time, the heat demand can be satisfied. By satisfying the heat demand, the efficiency of the cogeneration system 100 increases. In particular, by eliminating the time period during which the heat demand during operation is insufficient, the reliability of the cogeneration system 100 increases and the satisfaction of the user also increases.

  FIG. 8 shows a flowchart for explaining stop control of the fuel cell 10. First, the time is recognized by the time measuring means 54 (St91). When performing immediately after the start-up control (St81 to 85) of the fuel cell 10, the time recognized in St81 may be used. Then, it is determined whether the predicted power demand at that time is below the threshold (St92). If the predicted power demand is below the threshold, it is determined whether it is after the forced start time (St93). Here, “after the forced start time” means the time until the fuel cell 10 is started after the forced start time and the amount of stored heat reaches the heat demand. If it is not after the forced activation time, the fuel cell 10 is stopped (St96). If it is after the forced activation time, it is determined whether the amount of heat stored in the hot water storage tank 20 has reached the heat demand (St94). When the heat demand is reached, the fuel cell 10 is stopped (St96). When the heat demand is not reached, the condition for forced activation continues, so the fuel cell 10 is not stopped. However, even when it is not determined to stop the fuel cell 10 according to the previous determination, when it is determined that the amount of heat stored in the hot water storage tank 20 is full (St95), the fuel cell 10 is stopped (St96). ). This is because the cooling water of the fuel cell 10 is not cooled by the heat exchanger 30 and the fuel cell 10 cannot be cooled. That is, the time when the amount of heat stored in the hot water storage tank 20 is full is when the volume of hot water in the hot water storage tank 20 is full and the hot water temperature is equal to or higher than a predetermined temperature. Here, the predetermined temperature is a temperature at which the cooling water of the fuel cell 10 can be cooled, and a temperature at which the cooling water can be cooled to the cooling water inlet temperature of the fuel cell 10. The stop control of the fuel cell 10 is performed by the stop control means 58 of the control device 50.

  Next, output control of the fuel cell 10 will be described. When the fuel cell 10 has high power generation efficiency when operating at the rated output, it is preferable to operate at the rated output. However, it is assumed that surplus power, which is the difference from the actual power demand, is beneficially used, such as reverse power flow to the power system of the power company or heating of the hot water storage tank 20. By the way, when generating more power than the required power demand at the rated output, the amount of heat generated by the power generation also increases. Then, the heat storage in the hot water storage tank 20 tends to become full. Therefore, when there is a possibility that the heat storage is full, it is better to suppress the output of the fuel cell 10, and control is performed so that the output corresponds to the actual or predicted power demand. Even if power is generated at the output corresponding to the predicted power demand, if it is predicted that the heat storage will be full, for example, stop the operation in a small time zone with a low power generation efficiency, and the output will be large and rated output. It is preferable to operate in a time zone in which operation is possible because the overall efficiency becomes high.

  In addition, when beneficial utilization of surplus power such as reverse power flow to the power system of the power company is not expected, the output is set to be less than the power demand. This is because surplus power cannot be processed. In this case, it is safer and more preferable to operate the fuel cell 10 so as to output electric power slightly less than the electric power demand, and to purchase the shortage from the electric power system of the electric power company. The output control of the fuel cell 10 is performed by the output control means 59 of the control device 50. The start control means 53, the stop control means 58, and the output control means 59 each constitute part of the operation control means of the fuel cell 10.

  When the operation control (St80) of the fuel cell 10 is completed, the operation is repeated from the prediction of power demand (St30) after confirming that a predetermined time has elapsed by the time measuring means 54. This repetition is performed only for the cycle unit of the operation control of the cogeneration system 100, typically for one day.

  In the description so far, the activation non-permission time zone has been described as being input by the user or using the previous day's activation non-permission time zone. However, the activation non-permission time zone may be adjusted according to actual results. For example, when the time zone for canceling the startup non-permission time zone continues for several days such as 3 days with respect to the startup non-permission time zone input by the user, the time zone is changed from the startup non-permission time zone. By removing it, the fuel cell 10 can be easily started. Alternatively, if there is a continuous time for canceling the startup disapproval time zone on a specific day of the week, the time zone may be excluded from the start-up disapproval time zone depending on the specific day of the week, for example, based on the results for one week or one month. This makes it easy to start up the fuel cell 10. Alternatively, if the time for canceling the start-up non-permitted time zone occurs continuously according to the season, for example, based on the results for one year, the time zone may be excluded from the start-up non-permitted time zone depending on the specific season. Thus, the fuel cell 10 can be easily started. As described above, it is effective to store the actual value in the activation disapproval time zone in the storage unit 55.

  In the control of the operation so far, starting and stopping of the fuel cell 10 are controlled based on the predicted power demand or heat demand. This is because power demand and heat demand are regularly predicted, so that actual power demand and heat demand are reflected in the predicted power demand and heat demand. However, the start and stop of the fuel cell 10 may be controlled with reference to the actual power demand and heat demand in addition to the predicted power demand or heat demand. For example, the actual power demand is used as the power demand used in the determination whether the power demand is equal to or higher than the threshold (see St82 in FIG. 7) or the power demand is below the threshold (see St92 in FIG. 8). May be.

  In the above description, the fuel cell 10 is used as the power generation device. As the fuel cell 10, any type of fuel cell such as a polymer electrolyte fuel cell and a solid oxide fuel cell can be used. The polymer electrolyte fuel cell can be operated at a relatively low temperature, and the apparatus can be downsized. Therefore, the polymer electrolyte fuel cell is suitable for use in homes, small apartment houses, or small offices. Alternatively, instead of the fuel cell 10, other types of power generation devices such as a gas turbine power generation device and a steam turbine power generation device may be used. In the gas turbine power generator, turbine exhaust as well as cooling water is used as a heat source and can be used to warm hot water. In the steam turbine power generator, the heat recovered when steam is condensed can also be used to warm the hot water.

It is a block diagram which shows the structure of the cogeneration system which is embodiment of this invention. It is a flowchart which shows control of operation | movement of a cogeneration system. It is a graph of the example of a fluctuation | variation of the electric power demand per day of a general household. It is a graph of the example of a fluctuation | variation of the heat demand per day of a general household. 5 is a graph of fluctuation of an average hot water supply load per hour in the fluctuation example of the hot water supply load shown in FIG. 4. It is a flowchart explaining the operation | work procedure which resets a forced starting time. It is a flowchart explaining starting control of a fuel cell. It is a flowchart explaining stop control of a fuel cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell 11 Cooling water piping 12 Fuel gas piping 13 Oxidant gas piping 16 Electric power cable 20 Hot water storage tank 21 Hot water circulation piping 22 Hot water supply piping 30 Heat exchanger 50 Controller 51 Power demand prediction means 52 Heat demand prediction means 53 Start-up control Means 54 Timekeeping means 55 Storage means 56 Start non-permission time zone setting means 57 Forced start time setting means 58 Stop control means 59 Output control means 61 Start non-permission time zone input means 100 Cogeneration system

Claims (5)

A power generator that generates heat and generates heat;
A method of operating a cogeneration system comprising a heat storage section for storing the generated heat;
Predicting power demand over time;
Predicting heat demand over time;
Inputting a time zone during which the power generation device is not permitted to be activated by an input means;
Controlling the start and stop of the power generation device based on the predicted power demand and heat demand, and a time zone during which the start is not permitted;
How to operate the cogeneration system. Setting a time for forcibly starting the power generator;
The step of controlling the start and stop of the power generation device is based on the predicted power demand, heat demand, a time zone during which the start is not permitted, and a time at which the power generation device is forcibly started. Control the start and stop of
The operation method of the cogeneration system according to claim 1. When a predetermined amount or more of power demand is continuously predicted for a predetermined time or more, the power generation device is started by canceling the time zone in which the start is not permitted;
The operation method of the cogeneration system according to claim 1 or 2. A power generator that generates electricity and generates heat;
A heat storage section for storing the generated heat;
A power forecasting means for forecasting power demand;
Heat demand prediction means for predicting heat demand;
A start non-permission time zone input means for inputting a start non-permission time zone that does not permit the start of the power generator;
A minimum operation power storage means for storing the minimum operation power;
A time measuring means for measuring time;
Activation control means for activating the power generation device if the time measured by the timing means is not the activation-not-permitted time zone and the power demand predicted by the power demand prediction means is greater than or equal to the minimum operating power And comprising:
Cogeneration system. The power generation device is a fuel cell that generates power using hydrogen as a fuel;
The cogeneration system according to claim 4.

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