JP4330543B2 - 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 a main output operation that sets an output to a main output that is smaller than the power load by a suppression width.

In such a cogeneration system, a combined heat and power supply device such as an engine-driven generator or a fuel cell is provided, and the generated power of the combined heat and power supply device is supplied to a power consuming unit such as an electric device, and the generated heat of the combined heat and power device is, for example, The hot water heated by the heat is temporarily stored in a hot water storage tank and supplied to a heat consuming unit such as a hot water supply unit or a heating device.
And by providing such a cogeneration system in each home, etc., at least part of the power consumed in that home can be supplemented with the power generated by the combined heat and power supply device, so that the power received from the commercial power source is reduced. Moreover, since the heat generated at that time can be used as hot water, it is effective in terms of energy saving and economical efficiency.

  In such a cogeneration system, for example, by the operation control means, the set output of the combined heat and power unit is suppressed more than the power load in the power consumption unit in a relatively short output adjustment period such as several minutes (for example, 1 minute). There is a case where the main output operation is set to be performed with a small main output (see, for example, Patent Document 1).

In other words, in the cogeneration system, since the output of the combined heat and power device cannot follow the sudden decrease in the power load sensitively, by making the generated power of the combined heat and power device smaller than the power load by the suppression width, It is intended to suppress the generation of surplus power that is a surplus with respect to the power load of the generated power of the cogeneration apparatus.
And when surplus power is generated even if the generated power of the combined heat and power supply device is made smaller than the power load by the suppression width in this way, this surplus power is converted into heat stored in the hot water storage tank by the electric heater. Become.

JP 2004-286008 A

In executing the above main output operation, it is desired to suppress the generation of surplus power as much as possible and to cover the power load with the generated power as much as possible. However, in the past, since the suppression width was set to a certain size, the suppression width is not an appropriate size according to the operation status of the location where the cogeneration system is installed. There is a possibility that the generation of surplus power cannot be appropriately suppressed because the suppression width is too small, or the generation power becomes considerably smaller than the power load although the suppression width is too large to suppress the generation of surplus power. Therefore, improvement was desired.
In other words, if the operating conditions at the location where the cogeneration system is installed fluctuates rapidly in the range where the power load is large and the fluctuation occurs frequently, it is desirable to set the suppression range sufficiently large. In addition, if the operating status of the location where the cogeneration system is installed rarely fluctuates in a large range of power load, and the fluctuation does not occur so much, it is desirable to reduce the suppression range. Become.
By the way, it is considered that the follow-up capability with respect to fluctuations in the power load of the cogeneration system may vary depending on the system, and may change with use. As described above, when there is a difference in the tracking capability with respect to fluctuations in the power load of the cogeneration system, it is also desired to set the suppression width accordingly.

  The present invention has been made in view of the above problems, and its purpose is to execute the main output operation in which the output of the combined heat and power supply apparatus is set to the main output that is smaller than the power load by the suppression width. The present invention is to provide a cogeneration system that can adjust the suppression width appropriately to improve energy saving.

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, The cogeneration system is provided with operation control means capable of executing an electric main output operation in which the output of the cogeneration device is set to an electric main output that is smaller than a power load when the cogeneration device is in operation. The first 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 device,
The operation control means adjusts the suppression width based on surplus power calculated or measured by the surplus power deriving means in the main output operation.

  In other words, according to the first characteristic configuration of the cogeneration system, the operation control means performs the main output operation for following the power load in such a manner that the main output is set to be slightly smaller than the power load. In such a case, the surplus power is calculated or measured by the surplus power deriving means, and the suppression width is adjusted based on the surplus power calculated or measured by the surplus power deriving means, thereby generating surplus power. As much as possible, the power load can be covered by the generated power as much as possible.

  The 2nd characteristic structure of the cogeneration system which concerns on this invention exists in the point provided with the electric heater which converts the said surplus electric power into the heat stored in the said hot water storage tank.

  That is, according to the second characteristic configuration of the cogeneration system, even when the surplus power is converted into heat by the electric heater and used, the operation control means calculates or measures the surplus power deriving means in the main output operation. Since the surplus power can be reduced as much as possible by adjusting the suppression width based on the result, the generated heat of the electric heater can be reduced as much as possible to suppress the occurrence of the excess heat state.

  According to a third characteristic configuration of 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 the suppression width is set to the average value. Or it is in the point set according to an integrated value.

  That is, according to the third characteristic configuration of the cogeneration system, the operation control unit adjusts the suppression range based on the calculation or measurement result of the surplus power deriving unit in the main output operation. By setting according to the average value or integrated value of surplus power that fluctuates relatively slowly, not the instantaneous value of surplus power that fluctuates frequently, the output of the combined heat and power supply device becomes relatively stable, It is possible to suppress damage to the cogeneration device due to fluctuations and decrease in efficiency. In addition, as the average value or integrated value, a moving average value or moving integrated value that is repeatedly calculated while shifting the period, an average value by period or an integrated value by period that is calculated every predetermined period such as every day, etc. Can be used.

A cogeneration system according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the cogeneration system recovers the fuel cell 1 as a combined heat and power generation device that generates electric power and heat, and the heat generated by the fuel cell 1 with cooling water. A hot water storage unit 4 for storing hot water in the hot water tank 2 and supplying a heat medium to the heat consuming terminal 3 using the cooling water, and an operation control unit as operation control means for controlling the operation of the fuel cell 1 and the hot water storage unit 4. 5 or the like.

The output of the fuel cell 1 is adjustable, and an inverter 6 for system linkage is provided on the power output side of the fuel cell 1, and the inverter 6 uses the generated power of the fuel cell 1 for commercial use. It is configured to have the same voltage and the same frequency as the received power received from the power supply 7.
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.

The received power supply line 8 is provided with power load measuring means 11 for measuring the load power of the power load 9, and this power load measuring means 11 is a so-called so-called current flowing to the commercial power supply 7 side in the received power supply line 8. It is also configured to detect whether or not a reverse power flow occurs.
The electric 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, and the surplus power of the generated power is recovered by replacing the surplus power with heat. 12 is configured to be supplied.

The electric heater 12 is composed of a plurality of electric heaters, and is 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, and is connected to the output side of the inverter 6. ON / OFF is switched by the actuated switch 14.
The operation switch 14 is configured to adjust the power consumption of the electric heater 12 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. Yes.
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. The 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. The amount of power obtained by drawing the generated power of the fuel cell 1 from the power load and adding the power consumed by the electric heater 12 is covered by the received power received from the commercial power source 7. 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.

  The hot water storage unit 4 is configured to store hot water in a state where temperature stratification is formed, a hot water circulation pump 17 that circulates hot water in the hot water tank 2 through the hot water circulation path 16, and hot water for heat source through the heat source circulation path 20. A heat source circulation pump 21 to be circulated, a heat medium circulation pump 23 to circulate and supply the heat medium to the heat consuming terminal 3 through the heat medium circulation path 22, a hot water storage heat exchanger 24 to heat the hot water flowing through the hot water circulation path 16, The heat source heat exchanger 25 for heating the hot water for heat source flowing through the heat source circulation path 20, the heat exchanger for heat medium heating 26 for heating the heat medium flowing through the heat medium circulation path 22, and the fan 27 are operated. In this state, an auxiliary heating heat exchanger 29 for heating the hot water taken out from the hot water storage tank 2 by the combustion of the burner 28 and the heat source hot water flowing through the heat source circulation path 20 is provided.

The hot water circulation path 16 is branched and connected so that a part thereof is in parallel, a three-way valve 18 is provided at the connection location, and a radiator 19 is provided in the branched flow path. Yes.
Then, by switching the three-way valve 18, 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 circulated so as to bypass the radiator 19. It is comprised so that it may switch to the state to be made to.

The hot water storage heat exchanger 24 is configured to heat the hot water flowing through the hot water circulation path 16 by flowing the cooling water of the cooling water circulation path 13 that has recovered the heat output from the fuel cell 1. Has been.
In the heat source heat exchanger 25, the hot water for the heat source flowing through the heat source circulation path 20 is heated by flowing the cooling water in the cooling water circulation path 13 that has recovered the heat generated by the fuel cell 1. It is configured.
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, and the flow rate of the cooling water to be passed to the hot water storage heat exchanger 24 side and the heat source use are branched at the branch points. A diversion valve 30 is provided that adjusts the ratio of the flow rate of the cooling water that flows to the heat exchanger 25 side.
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 comprised so that it can also be made.

In the heat exchanger for heat medium heating 26, the hot water for the heat source heated by the heat exchanger for heat source 25 and the heat exchanger for auxiliary heating 29 is allowed to flow, thereby flowing through the heat medium circulation path 22. The heating medium is configured to be heated.
The said heat consumption terminal 3 is comprised by heating terminals, such as a floor heating apparatus and a bathroom heating apparatus.

  Further, a hot water supply load measuring means 31 for measuring the hot water supply heat load when supplying hot water taken out from the hot water tank 2 is provided, and a terminal thermal load measuring means 32 for measuring the terminal heat load at the heat consuming terminal 3 is also provided. ing.

  The operation control unit 5 controls the operation of the fuel cell 1 and the operation 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. By controlling the operating state of the circulation pump 21 and the heat medium circulation pump 23, a hot water storage operation for storing hot water in the hot water storage tank 2 and a heat medium supply operation for supplying the heat medium to the heat consuming terminal 3 are performed. Has been.

By the way, when hot water is supplied, the hot water taken out from the hot water tank 2 with the heat source intermittent valve 40 closed is configured to supply hot water, and the hot water taken out from the hot water tank 2 is heated by the auxiliary heating means M, Water is mixed with hot water taken out from the hot water storage tank 2, and hot water at a hot water supply set temperature set by a remote controller (not shown) is supplied.
Therefore, in the hot water tank 2, hot water is stored within the capacity of the hot water tank 2 by subtracting the hot water taken out 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 current power load currently requested 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, and the current power load is obtained as an average value of the power load in the previous output adjustment period. Further, the current power load may be obtained with a margin smaller than the actual power load.

In the electric main operation control as described above, there is a slight time delay from when the operation control unit 5 measures the current power load until the output of the fuel cell 1 is set to the electric main output.
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. Then, the generated power of the fuel cell 1 cannot sensitively follow the sudden decrease in the current power load, the generated power of the fuel cell 1 exceeds the current power load, and surplus power is generated. Electric power is supplied to the electric heater 12 described above.

  And the operation control part 5 reduces the surplus electric power in the electric main operation control, suppresses the heat generated by the electric heater 12, and suppresses the occurrence of a heat surplus state as described below. It is comprised so that driving | running | working may be performed. Hereinafter, this electric power output operation will be described.

  Incidentally, the excess heat state means, for example, that hot water stored in the hot water tank 2 is full and the radiator 19 is operated, or the heat output from the fuel cell 1 during the heat medium supply operation is consumed. It is larger than the terminal heat load and hot water supply load required at the terminal 3, the hot water stored in the hot water tank 2 is full, and the radiator 19 is in operation.

(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. 4 (a), in the main output operation, the main output that is smaller by the suppression width from the current power load is determined within the range from the minimum output to the maximum output, and the output of the fuel cell 1 is changed to the main output. Set to the determined main output.
That is, if 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, that output becomes the main output, and the output that is smaller by the suppression width from the current power load is less than the maximum output. When the output is large, the maximum output is determined as the main output, and when the output smaller than the current output load by the suppression width is smaller than the minimum output, the minimum output is determined as the main output.

  Then, even when the actual power output of the fuel cell 1 changes slightly with respect to the change state of the current power load, as shown in FIG. Surplus power can be suppressed.

  The main output is 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 in the main operation control. be able to. 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.

  Further, in this main output operation, the operation control unit 5 sets the suppression width, which is a width for reducing the output of the fuel cell 1 with respect to the current power load, to the surplus power calculated or measured by the surplus power deriving means X. Configured to adjust based on.

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

Next, 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 # 3).
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), the suppression width Ed is set to the moving average value Ave (Eo).
Thus, in the main output operation, by setting the suppression width Ed to the moving average value Ave (Eo) of the surplus power calculated or measured by the surplus power deriving means X, the generated power of the fuel cell 1 can be generated. As much as possible, the surplus power converted into heat by the electric heater 12 can be reduced as much as possible.
The suppression width Ed may be set not to the moving average value Ave (Eo) but to, for example, the surplus power Eo that is an instantaneous value.

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), it is necessary to suppress deterioration of energy saving due to excessive increase in received power from the commercial power supply 7. The suppression width Ed is set to the upper limit e1 (step # 4).
Note that step # 3 and step # 4 may be omitted, and the suppression width Ed may always be set to the moving average value Ave (Eo). Moreover, you may adjust a suppression width | variety according to the average value according to a period calculated as an average value of the surplus electric power for every predetermined periods, such as every day, instead of the above-mentioned moving average value. In addition, instead of the above moving average value, the amount of suppression is adjusted according to the cumulative integrated value of surplus power for a certain period in the past and the integrated value by period calculated as the integrated value of surplus power for each predetermined period such as every day. It doesn't matter.

  Furthermore, the operation control part 5 can set the upper limit e1 of the suppression width Ed in a form in which a heat shortage state to be described later is not predicted, assuming that the main output operation is performed.

  Note that the heat shortage state means, for example, that the hot water stored in the hot water tank 2 is empty and the auxiliary heating means M is operated, or the heat output from the fuel cell 1 during the heating medium supply operation. The hot water stored in the hot water tank 2 is smaller than the terminal heat load and hot water supply load required by the heat consuming terminal 3, and the auxiliary heating means M is activated. For example, as shown in FIG. 5, when it is assumed that the predicted power load and the predicted heat load in the determination target period such as one day are obtained and the main output operation is executed for the predicted power load, the fuel cell 1. It can be determined whether or not a heat shortage state occurs in which the generated heat is insufficient with respect to the predicted heat load.

That is, by changing the main output and determining whether or not the above heat shortage occurs, it is assumed that the main output operation has been executed. The range can be obtained, and the suppression width for the current power load at the lowest limit of the main output range is determined as the upper limit e1.
And by restrict | limiting so that the suppression width | variety Ed may become the upper limit e1 or less, generation | occurrence | production of the heat shortage state by performing an electric main output driving | running | working can be suppressed, As a result, deterioration of energy saving property is avoided. can do.
In the case where it is not necessary to suppress the occurrence of the heat shortage state, it may be omitted to limit the suppression width Ed to the upper limit value e1 or less.

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. Power load and time-series heat load are managed every unit time such as one 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.

  In the said embodiment, in addition to the hot water 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, Hot water supply is not provided without providing the heat consumption terminal 3. It is good also as a cogeneration system which makes a heat load a heat load.

  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 above embodiment, the operation control means 5 is based on the surplus power calculated or measured by the surplus power deriving means X in the main power output operation that is normally performed, with the surplus power deriving means X calculating the suppression width for the current power load. However, in the main output operation that is primarily executed, the suppression width may be adjusted based on the surplus power. For example, in the main output operation that is executed at the time when the excess heat state is predicted or when the excess heat state is generated, the adjustment range is adjusted based on the excess power. The heat generated by the electric heater 12 may be suppressed by reducing the surplus power, and the excess heat state may be avoided.

  In the above embodiment, the fuel cell 1 is exemplified as the combined heat and power device. However, as the combined heat and power device, for example, a combination of an internal combustion engine such as a gas engine and a power generation device, or an external combustion engine such as a Stirling engine and power generation. It is also possible to adapt a combination with a device.

  In the above embodiment, the electric heater 12 that converts surplus power into heat is provided and the heat generated by the surplus power is used. However, the surplus power may be used for another purpose. For example, you may comprise so that surplus electric power may be sold outside in the form of making it flow backward to the commercial power supply 7 side.

  The cogeneration system according to the present invention includes, for example, a fuel cell as a combined heat and power supply device, and when executing a main output operation in which the output of the combined heat and power supply device is set to a main output that is smaller than the power load by a suppression width, the suppression is performed. The present invention can be applied to a cogeneration system for appropriately adjusting the width and improving energy saving.

Schematic configuration diagram of cogeneration system Cogeneration system control block diagram Illustration of main operation control Explanatory diagram in main output operation Graph showing predicted power load and predicted heat load Flow chart showing adjustment process of suppression width in main output operation

Explanation of symbols

1: Fuel cell (cogeneration device)
2: Hot water storage tank 5: Operation control unit (operation control means)
12: Electric heater X: Surplus power deriving means

Claims (3)

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, and outputs the power of the combined heat and power device during operation of the combined heat and power device A cogeneration system provided with an operation control means capable of executing a main output operation set to a main output smaller than the suppression width,
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 cogeneration system in which the operation control means adjusts the suppression width based on surplus power calculated or measured by the surplus power deriving means in the main output operation.   The cogeneration system of Claim 1 provided with the electric heater which converts the surplus electric power into the heat stored in the hot water storage tank.   The operation control unit calculates an average value or an integrated value of surplus power calculated or measured by the surplus power deriving unit, and sets the suppression width according to the average value or the integrated value. The described cogeneration system.

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