JP4549308B2 - Cogeneration system - Google Patents

Description

  The present invention relates to a combined heat and power device that generates heat and electric power, a hot water storage tank that collects heat generated by the combined heat and power device and stores it as hot water, and the combined heat and power device when the combined heat and power device is in operation. The present invention relates to a cogeneration system provided with operation control means capable of executing electric main operation control for causing an output to follow an electric power load.

Such a cogeneration system includes a combined heat and power supply device such as an engine-driven generator and a fuel cell, and supplies the generated power of the combined heat and power supply device to a power consumption unit such as an electric device. Moreover, the heat generated by the combined heat and power supply device is temporarily stored in a hot water storage tank as hot water heated by the heat, for example, and supplied to a heat consuming unit such as a hot water supply unit or a heating device.
When the cogeneration system configured as described above is provided in each household or the like, at least a part of the power consumed in the household can be supplemented with the generated power of the combined heat and power supply apparatus. As a result, the power received from the commercial power source can be reduced, and the heat generated during power generation can be used for heating hot water, which is effective in terms of energy saving and economy.

  Such a cogeneration system performs, for example, electric main operation control that causes the set output of the combined heat and power supply to follow the power load in the power consuming unit in a relatively short output adjustment period such as several minutes (for example, one minute). The operation control means may be configured to execute.

  In the cogeneration system that executes the main operation control, the current power load can be covered with the generated power by executing the main operation control. However, it does not correspond to the presently required current heat load, and a heat surplus state in which heat is excessive with respect to the current heat load may occur, resulting in deterioration of energy saving performance.

  Therefore, the operation control means reduces the output of the combined heat and power unit when it is predicted that the heat load will be relatively small with respect to the amount of heat generated by the combined heat and power unit when performing the main operation control. There is also a cogeneration system that suppresses the generation of heat in the combined heat and power supply apparatus and suppresses the above heat surplus state (see, for example, Patent Document 1).

JP 2004-286008 A

In such electric main operation control, there is a slight delay time until the current power load is measured, the output of the cogeneration device is set by the operation control means, and the output of the cogeneration device follows. For example, when the electric power load fluctuates abruptly during the main operation control, the set output of the combined heat and power supply apparatus cannot be pursued sensitively. As a result, the generated power of the combined heat and power device exceeds the power load, and surplus power that is a surplus of the generated power of the combined heat and power supply device with respect to the power load may be generated.
This surplus power can be converted to heat stored in a hot water tank by an electric heater or the like and used effectively. However, there are cases where surplus power is not effectively used, such as the above-described surplus heat state, for example, a state where there is not much heat load required at that time and the hot water stored in the hot water tank is full. Therefore, in the heat surplus state, it is preferable that generation of surplus power that is a surplus with respect to the power load of the generated power of the combined heat and power supply apparatus is suppressed as much as possible.

  The present invention has been made in view of the above problems, and its purpose is to appropriately reduce the output of the combined heat and power supply device at a time when a surplus heat state is predicted or when a surplus heat state occurs. By this, it exists in the point which provides the cogeneration which can suppress appropriately the deterioration of the energy saving property accompanying a heat surplus state.

A cogeneration system according to the present invention for achieving the above object includes a combined heat and power device that generates heat and electric power, a hot water storage tank that collects the heat generated by the combined heat and power device and stores it as hot water, Operation control means for executing electric main operation control for causing the set output of the combined heat and power supply device to follow a power load during operation of the combined heat and power supply device is provided, and has the following characteristics.
That is, the characteristic configuration includes surplus power deriving means for calculating or measuring surplus power that is a surplus with respect to the power load of the generated power of the combined heat and power supply device, and the operation control means is configured to output the power to the predicted power load. When it is assumed that the main operation control has been executed, the occurrence of a heat surplus state is predicted, or when the power load increases at a heat surplus handling time, which is a time when a heat surplus state occurs , the thermoelectric power As an output reduction operation for reducing the output of the co-feeder, the following response state reduction operation is configured to be executable.
The response state lowering operation is to set the response state of the set output to the power load on the low side, which is the side on which the follow-up becomes dull, and based on the surplus power calculated or measured by the surplus power deriving means, The response state is adjusted.

According to this characteristic configuration, when the power load increases at the time when the heat surplus is dealt with, the operation control means executes the output reduction operation to reduce the output of the combined heat and power supply device. The state can be suppressed.
Further, according to this characteristic configuration, surplus power is derived (calculated or measured) by the surplus power deriving unit, and based on this surplus power, the operation control unit performs a response state decreasing operation as an output decreasing operation in the main operation control. I do. Then, during the response state decreasing operation, the response state of the set output with respect to the power load is adjusted based on the surplus power. As a result, it is possible to suppress the generation of surplus power as much as possible at the time of dealing with surplus heat, and to cover the power load as much as possible with the power generated by the combined heat and power supply device. As a result, it is possible to provide a cogeneration capable of improving energy saving.

  Further, the cogeneration system according to the present invention is characterized in that, in the response state lowering operation, the operation control means adjusts the response state to a lower side, which is a side where follow-up becomes dull as the surplus power is larger. And

  It is not desirable to generate more surplus power when the surplus power is already large in the heat surplus handling period. According to this feature, the response state is adjusted to the lower side, which is the side on which the follow-up becomes duller as the surplus power is larger, so that the follow-up of the set output of the combined heat and power device becomes dull with respect to fluctuations in the power load. As a result, the generation of surplus power is also suppressed.

  Further, in the cogeneration system according to the present invention, in the response state lowering operation, when the power control decreases, the operation control unit sets the response state to a higher response state, and the power load Is increased, the response state is adjusted on the lower side based on the surplus power.

When the power load decreases, if the response state is low (dull), surplus power is generated. That is, after the electric power load is derived, there is a slight delay time until the output of the cogeneration device is set by the operation control means and the output of the cogeneration device follows. Due to this delay time, the generated power of the heat transfer device exceeds the power load, and surplus power is generated. Therefore, when the power load decreases, if the response state is lowered based on the increase in surplus power, the delay time is further increased, and more surplus power is generated.
According to this feature, when the power load decreases, the response state is set to the higher side, such as being fixed to the maximum. Therefore, the delay time causing the surplus power generated as described above is suppressed to the minimum, and the generation of surplus power can be suppressed.
On the other hand, according to the present feature, when the power load increases, the response state is adjusted on the lower side than the high side so that the set output of the combined heat and power supply device follows the power load. Therefore, it is possible to further suppress the generation of surplus power during the time when the excess heat is dealt with, and to improve energy saving.

  In addition, the cogeneration system according to the present invention includes an electric heater that converts the surplus power into heat stored in the hot water storage tank.

According to this feature, surplus power can be converted into heat and used by the electric heater. And since this converted heat can be consumed in the thermal load which this system has or is connected to this system, energy can be used effectively.
However, in a heat surplus state in which the current heat load is small with respect to the heat to be converted, energy saving may be deteriorated.
According to the present invention, even when such an electric heater is provided and surplus power can be effectively used, surplus power can be reduced as much as possible. As a result, the heat generated by the electric heater can be reduced as much as possible to suppress the occurrence of a surplus heat state, and energy saving can be improved.

  Further, in the cogeneration system according to the present invention, the operation control unit calculates an average value or an integrated value of the surplus power calculated or measured by the surplus power deriving unit, and according to the average value or the integrated value The response state is adjusted.

According to this feature, when the operation control means adjusts the response state based on the result of derivation of surplus power in the response state lowering operation, the operation control means fluctuates relatively slowly instead of the instantaneous value of surplus power that fluctuates frequently. It is set according to the average value or integrated value of surplus power. Accordingly, the output of the combined heat and power device can be changed relatively stably, and damage to the combined heat and power device and a decrease in efficiency due to frequent fluctuations in the output can be suppressed.
In addition, as the average value or the integrated value, a moving average value or a moving integrated value that is repeatedly calculated sequentially while shifting the period, an average value for each period that is calculated every predetermined period such as every hour or every day, or An integrated value for each period can be used.

  In the cogeneration system according to the present invention, the operation control means causes the set output of the combined heat and power device to follow the power load at every predetermined output adjustment period in the response state decreasing operation. And the response state is a change speed at which the set output is changed in the output adjustment period.

  According to this feature, as described above, the changing speed at which the setting output of the cogeneration device is changed is adjusted based on the surplus power. When the change speed is adjusted to the slow side, the response state is adjusted to the low side, that is, in a direction in which the follow-up is dull. Therefore, the response state can be favorably changed according to the change speed.

  In the cogeneration system according to the present invention, the operation control means causes the set output of the combined heat and power device to follow the power load at every predetermined output adjustment period in the response state decreasing operation. The response state is a waiting time until the change of the set output is started in the output adjustment cycle.

  According to this feature, as described above, the standby time until the setting output of the cogeneration device is changed is adjusted based on the surplus power. When this standby time is adjusted to the long side, the response state is adjusted to the low side, that is, in a direction in which the follow-up is dull. Therefore, the response state can be changed favorably depending on the waiting time.

Further, the cogeneration system according to the present invention, when the operation efficiency at the partial output of the combined heat and power device is higher than the operation efficiency when the main operation control is executed, as the output reduction operation, the combined heat and power supply The operation control means executes a partial output operation for setting the output of the device to a partial output,
When the operation efficiency at the partial output of the cogeneration device is lower or equivalent to the operation efficiency when the main operation control is executed, the response state reduction operation is used as the output reduction operation. The means executes.
Here, the operation efficiency at the partial output of the cogeneration apparatus is equivalent to the operation efficiency when the main operation control is executed includes that the difference in operation efficiency is within about 5%.

According to this feature, since the operation control means selects and executes an appropriate output reduction operation based on the operation efficiency and reduces the output of the combined heat and power supply device at the time of dealing with the heat surplus, the heat surplus state is reduced. Can be suppressed.
Further, when the operation efficiency at the partial output of the combined heat and power device is higher than the operation efficiency when the main operation control is executed, the operation control means sets the output of the combined heat and power device to the partial output. Judge that the energy-saving performance does not deteriorate so much. And as the said output reduction operation, the partial output operation which sets the output of a cogeneration apparatus to partial output is performed, and the generated heat of a cogeneration apparatus is suppressed to the minimum. As a result, the excess heat state can be efficiently and reliably suppressed, and the deterioration of the energy saving property associated with the excess heat state can be significantly suppressed.
In addition, the said partial output can be set as an output which exhibits the highest driving | running efficiency in the minimum output or the output lower than an electric power load, for example.

  On the other hand, when the operation efficiency at the partial output of the combined heat and power device is smaller than the operation efficiency when the electric main operation control is executed, the operation control means sets the output of the combined heat and power device to the partial output. Judged that the energy savings will deteriorate. Then, as the output reduction operation, not the partial output operation but a response state reduction operation that adjusts a response state in which the electric power generated by the combined heat and power supply device follows the power load and reduces the response state is executed. Thereby, the surplus electric power converted into heat by the heat generated by the combined heat and power supply device or the electric heater can be suppressed, and the deterioration of energy saving due to the excess heat state can be suppressed. In addition to this, unlike the prediction, it is possible to suppress the occurrence of a heat shortage state with respect to a heat load that is actually relatively large, and it is also possible to suppress the deterioration of energy saving due to such a heat shortage state.

Hereinafter, a cogeneration system according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, this cogeneration system includes a fuel cell 1 and a hot water storage unit 4. The fuel cell 1 is a cogeneration apparatus that generates electric power and heat. The hot water storage unit 4 collects heat generated by the fuel cell 1 with cooling water, and uses the cooling water to store hot water in the hot water tank 2 and supply a heat medium to the heat consuming terminal 3. Further, as shown in FIG. 2, the operation of the fuel cell 1 and the hot water storage unit 4 is controlled by an operation control unit 5 as operation control means.

The fuel cell 1 is configured such that its output can be adjusted. On the power output side of the fuel cell 1, an inverter 6 for system linkage is provided. The inverter 6 is configured to have the same voltage and the same frequency as the received power received from the commercial power supply 7 by the power generated by the fuel cell 1.
The commercial power source 7 is, for example, a single-phase three-wire system 100/200 V, and is electrically connected to a power load 9 such as a television, a refrigerator, or a washing machine via a received power supply line 8.
The inverter 6 is electrically connected to the received power supply line 8 via the generated power supply line 10, and the generated power from the fuel cell 1 is supplied to the power load 9 via the inverter 6 and the generated power supply line 10. It is configured to be.

  The received power supply line 8 is provided with power load measuring means 11 for measuring the load power of the power load 9. The power load measuring means 11 is also configured to detect whether or not a so-called reverse power flow in which a current flows on the commercial power supply 7 side in the received power supply line 8 occurs. Then, the power supplied from the fuel cell 1 to the received power supply line 8 is controlled by the inverter 6 so that a reverse power flow does not occur. The surplus power generated by the fuel cell 1 is supplied to an electric heater 12 that recovers the surplus power by converting it into heat.

The electric heater 12 is composed of a plurality of electric heaters. These electric heaters 12 are provided so as to heat the cooling water of the fuel cell 1 flowing through the cooling water circulation path 13 by the operation of the cooling water circulation pump 15. Each electric heater 12 is switched ON / OFF by an operation switch 14 connected to the output side of the inverter 6.
The operation switch 14 is configured such that the power consumption of the electric heater 12 is adjusted according to the amount of surplus power so that the power consumption of the electric heater 12 increases as the amount of surplus power increases. ing.
The surplus power can be calculated as a power value obtained by subtracting the power load measured by the power load measuring means 11 from the generated power of the fuel cell 1 measured as the output of the inverter 6. Therefore, the power load measuring means 11 and the inverter 6 also function as surplus power deriving means X for calculating or measuring surplus power.

Incidentally, the surplus power is calculated as described above, and ON / OFF is switched by the operation switch 14 so that the power consumption of the electric heater 12 becomes equal to or greater than the surplus power. Therefore, the amount of power obtained by subtracting the power generated by the fuel cell 1 from the power load measured by the power load measuring means 11 and adding the power consumed by the electric heater 12 is covered by the received power received from the commercial power source 7. become.
This surplus power may be calculated or measured by another method, for example, by providing surplus power measuring means capable of measuring the power supplied to the electric heater 12 as surplus power.

As shown in FIG. 1, the hot water storage unit 4 includes a hot water tank 2, a hot water circulation pump 17, a heat source circulation pump 21, a heat medium circulation pump 23, a hot water heat exchanger 24, a heat source heat exchanger 25, a heat medium. A heating heat exchanger 26, an auxiliary heating heat exchanger 29, and the like are provided. These are a hot water circulation path 16 through which hot water in the hot water tank 2 flows, a heat source circulation path 20 through which hot water for heat source flows, and a heat medium circulation path 22 through which a heat medium circulated and supplied to the heat consuming terminal flows. Etc. are connected.
The hot water tank 2 stores hot water in a state where temperature stratification is formed. The hot water circulation pump 17 circulates hot water in the hot water tank 2 through the hot water circulation path 16. The heat source circulation pump 21 circulates the heat source hot water through the heat source circulation path 20. The heat medium circulation pump 23 circulates and supplies the heat medium to the heat consuming terminal 3 through the heat medium circulation path 22. The hot water storage heat exchanger 24 heats the hot water flowing through the hot water circulation path 16. The heat source heat exchanger 25 heats the heat source hot water flowing through the heat source circulation path 20. The heat medium heating heat exchanger 26 heats the heat medium flowing through the heat medium circulation path 22. The auxiliary heating heat exchanger 29 heats the hot water extracted from the hot water storage tank 2 by the combustion of the burner 28 and the hot water for the heat source flowing through the heat source circulation path 20 with the fan 27 operated.

The hot water circulation path 16 is branched and connected so that a part thereof is in parallel, and a three-way valve 18 is provided at the connection location. A radiator 19 is provided in one of the branched flow paths.
The operation control unit 5 switches the three-way valve 18 so that the hot water taken out from the lower part of the hot water tank 2 is circulated so as to pass through the radiator 19, and the hot water taken out from the lower part of the hot water tank 2 is passed through the radiator 19. It is configured to be switched to a state of being circulated so as to bypass.

The hot water storage heat exchanger 24 is configured to heat the hot water flowing through the hot water circulation path 16 by passing the cooling water of the cooling water circulation path 13 that has recovered the heat output from the fuel cell 1. Yes.
The heat source heat exchanger 25 is configured to heat the heat source hot water flowing through the heat source circulation path 20 by flowing the cooling water of the cooling water circulation path 13 that has recovered the heat generated by the fuel cell 1. Has been.
The auxiliary heating means M includes a fan 27, a burner 28, and an auxiliary heating heat exchanger 29.
Further, the heat source circulation path 20 is provided with a heat source intermittent valve 40 for intermittently flowing the heat source hot water.

The cooling water circulation path 13 is branched into a hot water storage heat exchanger 24 side and a heat source heat exchanger 25 side. At the branch point, a diversion valve 30 is provided for adjusting the ratio of the flow rate of the cooling water to be passed to the hot water storage heat exchanger 24 side and the flow rate of the cooling water to be passed to the heat source heat exchanger 25 side. Yes.
The diversion valve 30 allows the entire amount of cooling water in the cooling water circulation path 13 to flow to the hot water storage heat exchanger 24 side, or allows the entire amount of cooling water in the cooling water circulation path 13 to flow to the heat source heat exchanger 25 side. It is configured so that it can also be allowed to.

The heat exchanger 26 for heat medium heating is a heat medium that flows through the heat medium circulation path 22 by flowing hot water for the heat source heated by the heat exchanger 25 for heat source or the heat exchanger 29 for auxiliary heating. It is comprised so that it may heat.
The heat consuming terminal 3 is composed of a heating terminal such as a floor heating device or a bathroom heating device.

  Further, the hot water storage unit 4 includes a hot water supply load measuring means 31 for measuring a hot water supply heat load when hot water taken out from the hot water tank 2 is supplied, and a terminal heat load measuring means for measuring a terminal heat load at the heat consuming terminal 3. 32 is also provided.

  The operation control unit 5 controls the operation of the fuel cell 1 and the operating state of the cooling water circulation pump 15 while operating the cooling water circulation pump 15 during the operation of the fuel cell 1, as well as the hot water circulation pump 17 and the heat source circulation. The operating state of the pump 21 and the heat medium circulation pump 23 is controlled. The operation control unit 5 is configured to perform a hot water storage operation in which hot water is stored in the hot water storage tank 2 and a heat medium supply operation in which a heat medium is supplied to the heat consuming terminal 3 by these controls.

Incidentally, when hot water is supplied, the hot water taken out from the hot water storage tank 2 is supplied with the heat source intermittent valve 40 closed. That is, the hot water taken out from the hot water tank 2 is heated by the auxiliary heating means M, or the hot water taken out from the hot water tank 2 is mixed with water so that the hot water set temperature set by the remote controller outside the figure is set. It is configured to supply hot water.
Therefore, in the hot water tank 2, hot water is stored within the capacity range of the hot water tank 2 by subtracting the hot water extracted for hot water supply from the hot water added according to the output of the fuel cell 1. become.

First, the operation control of the fuel cell 1 by the operation control unit 5 will be described.
The operation control unit 5 executes main operation control for setting the output of the fuel cell 1 to the main output that follows the currently requested power load when the fuel cell 1 is in operation.

Specifically, the operation control unit 5 obtains the current power load for each relatively short predetermined output adjustment period such as one minute in the main operation control, and from the minimum output (for example, 250 W) to the maximum output (for example, 1000 W). 3), the main output following the current power load is continuously determined as shown in FIG. 3A, and the output of the fuel cell 1 is set to the determined main output.
The minimum output may be set to 0 W or an extremely small output close to it within an allowable range.

  The current power load is obtained based on the measured value of the power load measuring means 11. The current power load is obtained as an average value of the power load in the output adjustment period before the output adjustment period for setting the main output. At this time, the current power load may be obtained with a margin smaller than the actual power load. This margin can be used as an equivalent to the suppression width described later.

In the electric main operation control as described above, the operation control unit 5 sets the output of the fuel cell 1 to the electric main output after measuring the current power load, and until the output of the fuel cell 1 follows slightly, There is a delay time.
That is, as shown in FIG. 3B, the actual generated power of the fuel cell 1 changes slightly with respect to the change state of the current power load. And if the generated power of the fuel cell 1 cannot sensitively follow the sudden decrease in the current power load and the generated power of the fuel cell 1 exceeds the current power load, surplus power is generated. The surplus power is supplied to the electric heater 12 described above.
In addition, as shown in FIG. 4, even when the current power load tends to increase and the load fluctuates in a short period, the generated power of the fuel cell 1 partially exceeds the current power load, and surplus power Occurs.

  The operation control unit 5 is configured to execute the following main output operation in order to suppress the surplus power in the main operation control. Hereinafter, this electric power output operation will be described.

(Main output operation)
In the main output operation, the operation control unit 5 is configured to set the output of the fuel cell 1 to a main output that is smaller than the current power load by a predetermined amount or a reduction width.
That is, as shown in FIG. 5A, in the main output operation, the main output that is smaller by the suppression width from the current power load within the range from the minimum output to the maximum output is determined, and the output of the fuel cell 1 is changed to the main output. Set to the determined main output.
That is, when the output that is smaller by the suppression width from the current power load is within the range from the minimum output to the maximum output, the output becomes the main output. When the output smaller than the current power load by the suppression width is larger than the maximum output, the maximum output is determined as the main output. If the output that is smaller than the current power load by the suppression width is smaller than the minimum output, the minimum output is determined as the main output.

  When the operation control unit 5 executes such main output operation, the actual generated power of the fuel cell 1 is slightly delayed with respect to the change state of the current power load, as shown in FIG. Even when it changes with time, surplus power can be suppressed.

In the main output operation, the main output may be set as an output smaller by the suppression width than the main output set to follow the current power load within the range from the minimum output to the maximum output. it can. In this case, in order to prevent the main output from becoming less than the minimum output, when the output smaller than the main output by the suppression width is smaller than the minimum output, the minimum output is determined as the main output.
In the main output operation, it is not always necessary to set such a suppression width.

  On the other hand, even if the main output operation is performed using the suppression width, for example, the surplus power as shown in FIG. 4 may not be sufficiently suppressed. Therefore, the operation control unit 5 makes a response state in which the set output of the fuel cell 1 follows the current power load in this main output operation based on surplus power calculated or measured by the surplus power deriving means X. Configured to adjust. This adjustment is performed in the response state decreasing operation as the output decreasing operation described below. Details will be described later.

  When the operation control unit 5 assumes that the main power operation control is performed on the predicted power load, the operation control unit 5 is the time when the occurrence of the excess heat state is predicted or the time when the excess heat state occurs. At the time, it is configured to execute an output reduction operation for reducing the output of the fuel cell 1. Hereinafter, the output reduction operation will be described.

  The operation control unit 5 is configured to be able to execute a response state lowering operation described below as an output lowering operation.

(Response state lowering operation)
The operation control unit 5 is configured to set a response state for causing the output of the fuel cell 1 to follow the power load to a low side in the response state decreasing operation.
In addition, as described above, even if the main output operation is performed using the suppression width, for example, the surplus power as illustrated in FIG. 4 may not be sufficiently suppressed. Therefore, the operation control unit 5 makes a response state in which the set output of the fuel cell 1 follows the current power load based on the surplus power calculated or measured by the surplus power deriving means X in the response state decreasing operation. Configured to adjust.

  That is, as shown in FIG. 6, in the response state decreasing operation, the operation control unit 5 first calculates or measures the surplus power Eo by the surplus power deriving means X (step # 1). Then, the moving average value Ave (Eo) of the surplus power Eo is calculated from the current surplus power Eo and the surplus power Eo in the past certain period (step # 2).

Here, the operation control unit 5 determines whether or not the power load is increased (step # 3), and if the power load is not increased, the response state R is set to, for example, the highest response state Rmax. (Step # 7). That is, when the power load decreases, the operation control unit 5 makes the response state R follow the power load by fixing the response state R to the highest response state and responding. Here, the highest response state R refers to control that causes the set output of the fuel cell 1 to follow the power load at the fastest speed within the range of the characteristics of the fuel cell 1.
The response state Rmax is an example of a higher response state. Therefore, it may be set to a higher side other than Rmax.

  When the power load decreases, if the follow-up of the set output of the fuel cell 1 is slow, the power generated by the fuel cell 1 increases with respect to the power load, and surplus power is generated. However, as described above, if the response state R is fixed to the highest response state Rmax when the power load decreases (when it does not increase), the generation of surplus power can be suppressed.

  When it is determined in step # 3 that the power load increases, the operation control unit 5 adjusts the response state R so that the set output of the fuel cell 1 follows the power load as described below. Specifically, the operation control unit 5 determines the response state R based on a function F (see the following formula (1)) having a surplus power (including instantaneous value, average value, upper and lower limit values, etc.) as a variable x. By adjusting the response state R, the response state R is adjusted.

  R = F (x) (1)

Hereinafter, a procedure for determining the response state R based on the function F (x) will be described.
First, it is determined whether or not the moving average value Ave (Eo) of the surplus power Eo is larger than an upper limit value e1 (for example, 50 W) (step # 4). When the moving average value Ave (Eo) of the surplus power Eo is equal to or less than the upper limit value e1 (for example, 50 W), as shown in the following formulas (2) and (3), the variable x of the formula (1) is set. The moving average value Ave (Eo) of surplus power Eo is substituted. Then, the response state R is determined based on the substituted function F (x) (step # 6).

x ← Ave (Eo) (2)
R = F (Ave (Eo)) (3)

  On the other hand, when the moving average value Ave (Eo) of the surplus power Eo is larger than the upper limit value e1 (for example, 50 W), there is a possibility that power generation by the fuel cell 1 is suppressed more than necessary. This leads to an excessive increase in received power from the commercial power source 7 and may deteriorate the energy saving performance as a whole. Therefore, the input value to the function F (x) is set to the upper limit value e1 in order to suppress this deterioration in energy saving (step # 5).

Here, the response state R will be described.
FIG. 7 is a further enlarged graph showing the relationship between the current power load shown in FIG. 4 and the actual generated power of the fuel cell 1. T in the figure indicates the output adjustment period.
FIG. 7A shows the response state R when the response state R is the highest, that is, when the response is most sensitive. In the output adjustment period T, the power generation output of the fuel cell 1 increases at the highest response speed (at the highest speed), and surplus power is generated.

  FIG. 7B shows a case where the response state R is adjusted to a low side (dull side) compared to FIG. 7A. As shown in the figure, the change speed at which the set output is changed in the output adjustment period T is adjusted to the lower side. That is, the response state R in this case corresponds to the change speed (slope) of the set output. When the response state R is adjusted in this way, the generation of surplus power is suppressed as compared with the case where the response state R shown in FIG.

FIG.7 (c) has shown another form at the time of adjusting the response state R to the low side (dull side). As shown in the figure, a waiting time WT is provided before the change of the set output of the fuel cell 1 is started in the output adjustment period T. That is, the response state R in this case corresponds to the standby time WT. If the waiting time WT is adjusted to zero, it is equivalent to the best response state R. When the response state R is adjusted in this way, the generation of surplus power is suppressed as compared with the case where the response state R shown in FIG.
Further, the standby time WT may be a time that is an integral multiple of the output adjustment period T as shown in FIG. FIG. 8 shows an example in which the output adjustment period T is one time.
Further, the response state R may be adjusted by combining the change speed and the standby time.

In this way, in the response state decreasing operation, the response state R is determined based on the surplus power moving average value Ave (Eo) calculated or measured by the surplus power deriving means X, thereby generating power generated by the fuel cell 1. As much as possible, the surplus power converted into heat by the electric heater 12 can be reduced as much as possible.
In particular, even if surplus power is converted into heat by the electric heater 12 , it is effective if the surplus power is suppressed in a heat surplus state (heat surplus handling time) in which the heat is not effectively utilized.
The excessive heat state is, for example, a state where hot water stored in the hot water tank 2 is full and the radiator 19 is operated. Moreover, the hot water stored in the hot water tank 2 is full, and the heat output from the fuel cell 1 during the heating medium supply operation is larger than the terminal heat load or hot water supply load required by the heat consuming terminal 3, In this state, the radiator 19 is activated.

The response state R may be set not as a function of the moving average value Ave (Eo) but as a function of the surplus power Eo that is an instantaneous value, for example.
Further, Step # 4 to Step # 6 may be omitted, and the response state R may be always set to the moving average value Ave (Eo) or the surplus power Eo that is an instantaneous value. Moreover, you may adjust the response state R according to the period average value calculated as an average value of the surplus electric power for every predetermined periods, such as every day, instead of the said moving average value. In addition, instead of the moving average value, the response state R according to a periodical accumulated value calculated as a moving accumulated value of surplus power for a certain period in the past or an accumulated value of surplus power for each predetermined period such as every day. May be adjusted.

  Furthermore, the operation control unit 5 can set the upper limit value e1 of the response state R in a form in which a heat shortage state to be described later is not predicted when it is assumed that the response state lowering operation is executed.

The heat shortage state is a state in which, for example, hot water stored in the hot water tank 2 is empty and the auxiliary heating means M is operated. Further, the heat output from the fuel cell 1 during the heat medium supply operation is smaller than the terminal heat load or hot water supply load required by the heat consuming terminal 3, and the hot water stored in the hot water tank 2 is empty. Yes, the auxiliary heating means M is activated.
For example, as shown in FIG. 9, when the predicted power load and the predicted heat load in the determination target period such as one day are obtained and it is assumed that the response state reduction operation is executed for the predicted power load, the fuel cell 1 is generated. It is possible to determine whether or not a heat shortage state occurs in which heat is insufficient with respect to the predicted heat load.

That is, by changing whether the main power output is changed, it is determined whether or not the above heat shortage state occurs. A range can be determined. Then, the upper limit value e1 is determined based on the response state R with respect to the current power load at the lowest limit of the main output range.
By limiting the response state R so as to fluctuate below the upper limit value e1, it is possible to suppress the occurrence of a heat shortage state due to executing the response state lowering operation. As a result, it is possible to avoid deterioration in energy saving.

  Further, the operation control unit 5 is configured to be able to execute the following partial output operation as the output reduction operation in addition to the response state reduction operation.

(Partial output operation)
The operation control unit 5 is configured to set the output of the fuel cell 1 to a partial output in the partial output operation. And the surplus electric power mentioned above can be suppressed significantly by performing this partial output driving | operation.
The partial output can be set as a minimum output or an output that exhibits the highest operating efficiency among the outputs lower than the power load.

  As shown in FIG. 10, the operation control unit 5 determines whether or not it is time to deal with excess heat, which will be described later (step # 11). One of the state decreasing operations is performed to decrease the output (step # 12).

  That is, when the operation efficiency at the partial output of the fuel cell 1 is higher than the operation efficiency when the main operation control (main output operation) is executed, the operation control means 5 performs the output reduction operation as the fuel cell 1. Execute partial output operation to set the output of to partial output. On the other hand, when the operation efficiency at the partial output of the fuel cell 1 is lower or equal to the operation efficiency when the main operation control is executed, the response state reduction operation is executed as the output reduction operation.

Next, description will be added regarding the determination of the excess heat handling time in step # 11.
For example, as shown in FIG. 9, the operation control unit 5 obtains a predicted power load and a predicted heat load in a determination target period such as one day. Next, when it is assumed that the main operation control is executed for the predicted power load, it is determined whether or not a surplus heat state is generated in which the heat generated by the fuel cell 1 is greater than the predicted heat load. Then, the time zone before the occurrence of the excess heat state is determined as the time when the occurrence of the excess heat state is predicted.
In addition, the operation control unit 5 integrates the amount of heat released when the radiator 19 is activated to start heat dissipation, or the time when the integrated value is equal to or greater than the set value causes a heat surplus state. Ask as the time when.
And the time when generation | occurrence | production of the above heat surplus states is estimated, or the time when the heat surplus state has generate | occur | produced is determined as the said heat surplus handling time.

  Further, the operation control unit 5 determines whether to execute the partial output operation or the response state reduction operation as the output reduction operation based on the operation efficiency at the partial output of the fuel cell 1. It is configured.

That is, as shown in FIG. 11, is the operation efficiency A at the partial output of the fuel cell 1 higher than the operation efficiency when the main operation control is executed (that is, the operation efficiency at the main output of the fuel cell 1) a1? It is determined whether or not (step # 21).
When the operation efficiency A at the partial output of the fuel cell 1 is higher than the operation efficiency a1 when the main operation control is executed, the energy saving is not much by setting the output of the fuel cell 1 to the partial output. Judge that it will not deteriorate. Then, the operation control unit 5 is caused to execute the partial output operation as the output reduction operation (step # 22).
On the other hand, when the operation efficiency A at the partial output of the fuel cell 1 is lower than or equal to the operation efficiency a1 when the main operation control is executed, the output of the combined heat and power supply device is set to the partial output. Judgment that energy property deteriorates. Then, the operation control unit 5 is caused to execute the response state reduction operation as the output reduction operation (step # 23).

  The operating efficiency A and a1 are the following formulas as a power generation merit that is a merit of supplementing the power supplied to the power load 9 with the power generated by the fuel cell 1 instead of the power received from the commercial power supply 7. It can be obtained by the equation shown in (4).

  Operation efficiency (power generation merit) = output of fuel cell 1 × (1 / power generation efficiency of commercial power source 7−1 / power generation efficiency of fuel cell 1) (4)

  The operation control unit 5 itself may determine whether or not the operation efficiency A at the partial output of the fuel cell 1 in step # 21 is higher than the operation efficiency a1 when the main operation control is executed. However, the cogeneration system designer or user may make the determination separately. That is, the designer or user determines whether the operation control unit 5 is configured to perform the partial output operation as the output reduction operation or to perform the response state reduction operation. It doesn't matter.

  When the operation control unit 5 executes the determination in step # 21, the operation efficiency A at the partial output is calculated from the fuel consumption, generated power, and generated heat at the past partial output of the fuel cell 1. It can be configured to calculate and update as needed. With this configuration, it is possible to switch between performing the partial output operation or performing the response state decreasing operation as the output decreasing operation in accordance with a change in the state of the fuel cell 1 over time. it can.

  When the partial output is set to the minimum output, only the operation efficiency A at the minimum output can be updated at any time. On the other hand, when the partial output is an output that exhibits the highest operation efficiency among the outputs lower than the power load, the operation efficiency at each output of the fuel cell 1 that may be set as the partial output. A can be configured to update at any time as described above.

The time series power load and the time series heat load are managed by the operation control unit 5 as shown below.
That is, the operation control unit 5 uses, for example, a heat load as a hot water supply heat load and a terminal heat load, and converts each of an actual power load per unit time, an actual hot water supply heat load, and an actual terminal heat load into the power load measuring unit 11. And the output value of the inverter 6, the hot water supply thermal load measuring means 31, and the terminal thermal load measuring means 32.
And the operation control part 5 memorize | stores the value measured in the output value of the electric power load measurement means 11 and the inverter 6, the hot water supply heat load measurement means 31, and the terminal thermal load measurement means 32, and is time-sequentially. A simple electric power load and a time-series heat load are managed every unit time every hour.
In addition, when the operation control unit 5 updates the time-series power load and the time-series heat load according to the actual use situation, the output values of the power load measuring means 11 and the inverter 6, the hot water supply heat load, The value measured by the measuring means 31 and the terminal thermal load measuring means 32 and the value already stored are added together at a predetermined ratio, and the added value is stored.

  Hereinafter, first to third examples will be described as examples of the determination of the partial output operation and the response state lowering operation based on the operation efficiency at the time when the excess heat is dealt with and the setting method of the partial output in the partial output operation.

[First embodiment]
As a first example, an example in which the operation efficiency at each output of the fuel cell 1 obtained as a power generation merit by the above-described formula (4) is assumed to increase as the output increases as shown in Table 1 below. Will be described.
In the above formula (4), the power generation efficiency of the commercial power supply 7 is 0.366.

  When the main output following the current power load is 1000 W, 750 W or 500 W, the operation efficiency of the partial output smaller than the main output of the fuel cell 1 is the main output of the fuel cell 1. Lower than operating efficiency. Therefore, the output reduction operation is not the partial output operation in which the output of the fuel cell 1 is set to the partial output, but the response in which the response state of the set output of the fuel cell 1 with respect to the power load is set to the low side (the side where the follow-up becomes dull). The state reduction operation is executed by the operation control unit 5.

[Second Embodiment]
As a second example, an example in which the operation efficiency at each output of the fuel cell 1 obtained as the power generation merit by the above-described formula (4) is assumed to be lower as the output is larger as shown in Table 2 below. Will be described.
In the above formula (4), the power generation efficiency of the commercial power source 7 is 0.366.

  When the main output following the current power load is 1000 W, 750 W, or 500 W, the operation efficiency of the partial output (300 W) of the fuel cell 1 smaller than the main output of the fuel cell 1 is It is higher than the operating efficiency at the main output. Therefore, instead of the response state lowering operation in which the response state of the set output of the fuel cell 1 with respect to the power load is set to the low side (the side where the follow-up becomes dull), the partial output in which the output of the fuel cell 1 is set to the partial output (300 W). Operation is performed by the operation control unit 5.

[Third embodiment]
As the third embodiment, the operation efficiency at each output of the fuel cell 1 obtained as the power generation merit according to the above-described formula (4) is the highest when the output is 750 W, as shown in Table 3 below, A description will be given of an embodiment assuming a case where the power decreases in the order of 300 W and 1000 W. In the above formula (4), the power generation efficiency of the commercial power source 7 is 0.366.

When the main output following the current power load is 1000 W, the operation efficiency of the partial output (750 W) smaller than that main output of the fuel cell 1 is the operation efficiency at the main output of the fuel cell 1. Higher than efficiency. Therefore, not the response state lowering operation in which the response state of the set output of the fuel cell 1 with respect to the power load is set to the low side (the side where the follow-up becomes dull), but the partial output to set the output of the fuel cell 1 to the partial output (750 W) Operation is performed by the operation control unit 5.
When the main output following the current power load is 750 W or 500 W, the operating efficiency of the partial output smaller than the main output of the fuel cell 1 is the operating efficiency of the main output of the fuel cell 1. Lower than. Therefore, the operation control unit 5 does not perform partial output operation in which the output of the fuel cell 1 is set to partial output as the output reduction operation, but the response state of the set output of the fuel cell 1 with respect to the power load is low (the side where tracking is slowed down). The operation control unit 5 executes the response state lowering operation set to (1).

  In the said embodiment, in addition to the hot water storage tank 2, the heat consumption terminal 3 was provided, and the cogeneration system which made the heat load the hot water supply heat load and the terminal heat load was illustrated. However, it is good also as a cogeneration system which makes the hot water supply heat load a heat load without providing the heat consuming terminal 3.

  In the above embodiment, the electric heater 12 is configured to heat the cooling water of the fuel cell 1. However, the electric heater 12 may be configured to heat the hot water in the hot water tank 2. It is.

  In the said embodiment, the fuel cell 1 was illustrated as a thermoelectric power supply apparatus. However, it is also possible to apply a combination of an internal combustion engine such as a gas engine and a power generation device or a combination of an external combustion engine such as a Stirling engine and a power generation device as the combined heat and power supply device.

  The cogeneration system according to the present invention includes, for example, a fuel cell as a combined heat and power supply device, and appropriately reduces the output of the combined heat and power supply device at a time when the excess heat state is predicted. It can be applied to a cogeneration system and its operation method for appropriately suppressing the deterioration of the water.

Schematic configuration diagram of cogeneration system Cogeneration system control block diagram Illustration of main operation control Illustration of main operation control Explanatory diagram in main output operation Flow chart showing response state adjustment processing in main output operation Explanatory drawing which shows an example in the case of performing main operation control by adjusting the response state Explanatory drawing which shows the other example when adjusting a response state and performing main operation control Graph showing predicted power load and predicted heat load Flowchart showing determination processing for execution of response state lowering operation The flowchart which shows the determination process about the form of response state fall operation

Explanation of symbols

1: Fuel cell (cogeneration device)
2: Hot water storage tank 5: Operation control unit (operation control means)
6: Inverter (surplus power deriving means)
11: Power load measuring means (surplus power deriving means)
12: Electric heater X: Surplus power deriving means

Claims (8)

A combined heat and power device that generates heat and electric power together, a hot water storage tank that collects the heat generated by the combined heat and power device and stores it as hot water, and a set output of the combined heat and power device when the combined heat and power device is in operation A cogeneration system provided with operation control means for executing electric main operation control to follow the load,
Surplus power deriving means for calculating or measuring surplus power that is a surplus with respect to the power load of the generated power of the combined heat and power supply device,
The operation control means includes
In the electrostatic main driving timing generating heat odd state is predicted assuming that control has been executed, or heat-odd address period is the time the heat more than the state occurs with respect to the predicted power load, power load Increases
As the output reduction operation for reducing the output of the combined heat and power supply device, the response state of the set output with respect to the power load is set to the low side, which is the side where the follow-up becomes dull, and is calculated or measured by the surplus power deriving means A cogeneration system configured to be able to execute a response state lowering operation for adjusting the response state based on surplus power.   2. The cogeneration system according to claim 1, wherein the operation control unit adjusts the response state to a lower side that is a side on which the follow-up becomes duller as the surplus power is larger.   The operation control means sets the response state to a higher response state when the power load decreases, and reduces the response state based on the surplus power when the power load increases. The cogeneration system according to claim 1 or 2, which is adjusted on the side.   The cogeneration system as described in any one of Claims 1-3 provided with the electric heater which converts the said surplus electric power into the heat stored in the said hot water storage tank.   The said operation control means calculates the average value or integrated value of the said surplus electric power calculated or measured by the said surplus electric power deriving means, and adjusts the said response state according to the said average value or integrated value. The cogeneration system according to any one of the above. The operation control means is configured to cause the set output of the cogeneration device to follow the power load for each predetermined output adjustment period in the response state reduction operation.
The cogeneration system according to any one of claims 1 to 5, wherein the response state is a change speed at which the set output is changed in the output adjustment period. The operation control means is configured to cause the set output of the cogeneration device to follow the power load for each predetermined output adjustment period in the response state reduction operation.
The cogeneration system according to any one of claims 1 to 5, wherein the response state is a waiting time until the change of the set output is started in the output adjustment cycle. When the operation efficiency of the partial output of the cogeneration device is higher than the operation efficiency when the main operation control is executed, the operation control means partially outputs the output of the cogeneration device as the output reduction operation. Execute the partial output operation set to output,
When the operation efficiency at the partial output of the cogeneration device is lower or equivalent to the operation efficiency when the main operation control is executed, the response state reduction operation is executed as the output reduction operation. The cogeneration system according to any one of 1 to 7.

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