JP2676197B2 - Temperature control device for co-generation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for a cogeneration system capable of controlling a temperature of a heat source water at an engine inlet with high accuracy.

[0002]

2. Description of the Related Art An example of a control block of a conventional cogeneration system will be described with reference to FIG. In the figure, 1 is a generator that generates electric power, and 2 is an engine that drives the generator 1. The heat source water supplied from the pipe 16 is heated by the amount of heat generated in the engine 2. This heat source water is sent to the exhaust gas boiler 3 that uses the exhaust gas generated from the engine 2 by the pipe 13 and is heated. The heated heat source water flows through the pump 11 through the pipe 14 to the hot water utilization equipment 4 that uses the heat source water, and the heat source water is cooled here to cool the heat source water and pass through the pipe 15 to the radiator 6. Flowing. The heat source water cooled by the radiator 6 passes through the pipe 16 and flows into the engine 2 again.

The amount of heat used by the hot water utilization facility 4 is adjusted by the three-way valve 5. Further, in order to release the amount of heat that cannot be completely absorbed by the hot water utilization equipment 4 to the outside, a radiator 6 and a three-way valve 7 for adjusting the amount of heat released are provided. The valve opening of the three-way valve 7 is controlled by the controller 8.

In such a co-generation system, the temperature sensor 9 senses the inlet temperature of the engine 2 and inputs the measured value to the controller 8 as a feedback value. Next, the controller 8 calculates the deviation between the set value of the engine inlet temperature in the controller 8 and the measured value by the controller 8
ID calculation is performed to obtain the required valve opening. At the same time, the polygonal line function 18 shown in FIG. 2 sets the amount of heat to be absorbed from the valve opening degree of the three-way valve 5. The polygonal line function 18 is determined by the heat utilization situation on the heat utilization side. Then, the amount of heat to be released is calculated according to the deviation between the amount of heat output from the polygonal line function 18 and the amount of heat corresponding to the rated heat generation amount of the engine 2 calculated by the calculation device 12.

Next, the polygonal line function 19 shown in FIG. 5 sets the valve opening of the three-way valve 7 from the amount of heat to be radiated and outputs it as a feedforward value. Then, as shown in FIG. 5, it has characteristics of A, B, and C according to the season, and the function is set for each season. And this line function 19
Is added to the output of the controller 8 to adjust the valve opening of the three-way valve 7. By these operations, control is performed so that the inlet temperature of the engine 2 matches the set value.

Since most cogeneration systems are used in a system interconnection, they are usually operated continuously at a rated load. Therefore, in many cases, the amount of heat generated by the engine 2 is the rated amount of heat generated, which is not a problem.

FIG. 1 shows a case where the hot water utilization facility 4 is stopped when the amount of heat generated by the engine is constant in the co-generation system that uses only feedback control.
A characteristic diagram of 0 (a) will be described.

[0008] When the valve opening of the three-way valve 5 is opened to the bypass side at time t1 in order to reduce the amount of heat used to stop the hot water utilization facility 4, the three sides connected to the radiator 6 The valve opening of the valve 7 has a slow response, and the three-way valve 7 has time t1 ′.
Works from. Therefore, the required heat radiation does not increase with the temperature, and the engine inlet temperature rises. Similarly, when the hot water utilization facility 4 is operated, that is, when the three-way valve 5 is closed in the direction of increasing the amount of heat used by the hot water utilization facility at time t2, the three-way valve 7 is delayed from time t2. Since the operation starts from t2 ', it is delayed to reduce the amount of heat radiation, and the engine inlet temperature drops and cannot be kept constant.

The reason why the response of the valve opening degree of the three-way valve 7 is slow is that the gain of the feedback control system of the controller 8 is limited by the response of the temperature sensor 9.
In general, the temperature sensor 9 has a response time constant of about 180 seconds due to its structure, and the controller 8 is used in feedback control.
Response cannot be raised any further. Therefore, in order to increase the response speed, a signal calculated from the valve opening of the three-way valve 5 is added as a feedforward value to the output of the controller 8 to improve the responsiveness. Figure 10 (b)
The characteristic diagram of the hot water utilization equipment in the above shows the situation.

[0010]

By the way, FIG.
In the characteristic diagram of (b), the hot water utilization equipment 4 at time t1
When is stopped, the engine inlet temperature is kept constant due to the response improvement effect. However, in FIG. 10B, when the hot water utilization equipment 4 is brought into the operating state from the stop at the time t2, the temperature has the characteristic of overshooting. This is because the three-way valve 7 has different responses when it is opened and when it is closed. When the hot water utilization equipment 4 is in the operating state, the feed-forward control is performed so that the radiator 6
The one-way valve 7 operates in a direction that does not immediately release heat.

However, when the response of the three-way valve 7 is fast, there is high-temperature heat source water in the pipe between the hot water utilization equipment 4 and the radiator 6 before the hot water utilization equipment 4 is operating, and this is 3 It is bypassed by the one-way valve 7 and sent directly to the engine. For this reason, the engine inlet temperature rises. Since the heat source water is used as engine cooling water in this system, if the engine inlet temperature of the heat source water rises, there is a danger of causing a vapor phenomenon partially in the engine, which causes engine failure.

When the pipe between the hot water utilization equipment 4 and the radiator 6 is very long, when the hot water utilization equipment 4 is stopped, the cold heat source water flows into the engine 2 to lower the engine inlet temperature. To do. A decrease in the inlet temperature adversely affects the engine 2 and the hot water utilization facility 4 side, which is not preferable. This phenomenon occurs regardless of the difference in the response of the three-way valve 7 between when the valve is opened and when it is closed.

Furthermore, if the system is operated in winter with the setting of the polygonal line function 19 in FIG. 5 set to the characteristics of summer, there is a problem of supercooling, and conversely, the system is set in summer with the settings of winter. When operated, there was a problem of insufficient cooling. Therefore, a polygonal line function 1 that determines the valve opening of the three-way valve 7
It was necessary to reset 9 depending on the season, but that work was difficult.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a temperature control device for a cogeneration system that improves the reliability of the entire system by controlling the engine inlet temperature to be constant throughout the year. To do.

[0015]

In order to achieve the above object, the first aspect of the present invention is to heat the heat source water flowing through the system with the heat generated from the engine for driving the generator, and the heated heat source. Hot water utilization equipment that uses water, a first three-way valve that adjusts the amount of heat absorbed in the hot water utilization equipment, a radiator that releases the amount of heat that could not be used in the hot water utilization equipment, and a radiator In the temperature control device of the co-generation system, in which the second three-way valve that adjusts the amount of heat released, the engine, the hot water utilization facility, and each element of the radiator are connected by pipes through which heat source water flows, A temperature sensor that detects the engine inlet temperature and a feedback control is performed by calculating a valve opening set value of the second three-way valve so that the engine inlet temperature detected by the temperature sensor becomes a predetermined temperature. A controller to calculate the utilization heat of the hot water utilization facility from said first three-way valve of the valve opening signal,
From the heat quantity of the difference between this and the engine generated heat quantity, a valve opening command signal is calculated in a predetermined pattern, and the valve opening command signal is further delayed by a predetermined dead time. Is added to the valve opening set value of, and the valve opening of the second three-way valve is adjusted by the valve opening reference signal after the addition.

According to a second aspect of the present invention, the
In the temperature control device of the generation system, when the valve opening command signal is delayed by a predetermined dead time, the delay time is different between the case where the valve opening is increased and the case where the valve opening is reduced. It is characterized by.

According to a third aspect of the present invention, in the temperature control device of the cogeneration system according to the first or second aspect, the heat generation amount of the engine is calculated from the temperature difference between the inlet temperature and the outlet temperature of the engine and the flow rate. It is characterized by

According to a fourth aspect of the present invention, in the temperature control device of the cogeneration system according to the first to third aspects, instead of the valve opening signal of the first three-way valve,
It is characterized in that a valve opening command signal is calculated from a heat source water temperature at the outlet of the first three-way valve according to a predetermined function pattern.

According to a fifth aspect of the present invention, in the temperature control device of the cogeneration system according to the first to third aspects, instead of the valve opening signal of the first three-way valve,
The valve opening command signal is calculated according to a predetermined function pattern from the difference between the outlet temperature of the heat source water of the engine and the outlet temperature of the first three-way valve.

According to a sixth aspect of the present invention, in the temperature control device for a cogeneration system according to the first to fifth aspects, the function that determines the valve opening degree of the second three-way valve is the outside air temperature. It is characterized in that it is generated by a function generator with humidity input.

A seventh aspect of the present invention is the temperature control device for a cogeneration system according to the first to sixth aspects, wherein the engine includes an exhaust gas boiler device.

According to an eighth aspect of the present invention, in the temperature control device for a cogeneration system according to the first to seventh aspects, a plurality of the engines are provided and they are connected in parallel by piping. Characterize.

According to a ninth aspect of the present invention, in the temperature control device of the cogeneration system according to the first to eighth aspects, the engine includes a heat exchanger, and the heat source water exchanges heat from engine cooling water. It is characterized by being configured to obtain heat.

A tenth aspect of the present invention is the temperature control device for a cogeneration system according to any one of the first to ninth aspects, wherein a plurality of the hot water utilization facilities and the first three-way valve are installed and are connected in series or in parallel. It is characterized in that it is configured to be connected to.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention.
9 is a control block diagram of the co-generation system according to claim 10). The difference from the conventional example of FIG. 9 already described is that the feedforward signal generation block 20 and the function generator 24 are additionally set. Since these points are the same and the other points are the same, the same components are designated by the same reference numerals, and duplicate description will be omitted.

As shown in the figure, the temperature sensor 9 detects the engine inlet temperature, and the controller 8 calculates the deviation of the engine inlet temperature from the set value by PID to obtain the required valve opening of the three-way valve 7. , The three-way valve 7 is controlled so that the inlet temperature of the engine 2 matches the set value. Reference numeral 12 is a computing device that computes the amount of heat according to the rated amount of heat generated by the engine 2. Further, the polygonal line function 18 representing the absorbed heat quantity-valve opening characteristic of the heat utilization system from the valve opening of the three-way valve 5 for the hot water utilization equipment 4 is shown in FIG.
It has the characteristics shown in. The amount of heat absorbed is calculated using the line function 18, and the amount of heat to be released by the radiator 6 is calculated from the difference between the rated amount of generated heat of the engine 2 and the amount of absorbed heat.

Next, the polygonal line function 19 shown in FIG. 5 is a function showing the heat release amount-valve opening degree characteristic, and is generated in the function generator 24 from the input of the outside air temperature and the humidity. Radiator 6
This is because the heat dissipation characteristics of are dependent on the outside temperature and humidity. That is, when the outside air temperature is high, the temperature difference between the primary side and the secondary side of the radiator 6 is small, so that the heat radiation effect is reduced, and when the outside temperature is low, the temperature difference between the primary side and the secondary side of the radiator 6 is low. Is increased, the heat dissipation effect is improved. Regarding the humidity, when the humidity is low, the cooling water in the radiator 6 is easily vaporized, and the heat radiation effect is improved. On the contrary, when the humidity is high, the cooling water in the radiator 6 is less likely to be vaporized, and the heat radiation effect is reduced.

Further, as shown in FIG. 3, when the outside temperature T and the humidity W are input to the function generator 24, a function corresponding to the input is output. Here, the outside air temperature T and the humidity W are detected outdoors by the temperature sensor 25 and the humidity sensor 26. The input / output relationship of the function generator 24 is as shown in FIG.
For example, when the humidity W is “medium” and the outside air temperature T is “low”, the function B, that is, the function B in FIG. 5 is output.
The characteristic diagram of the polygonal line function 19 thus obtained is shown in FIG.
Is shown in The polygonal line function 19 generated by the function generator 24 is used to determine the valve opening degree of the three-way valve 7 of the radiator 6.

As shown in the block diagram of FIG. 6, in the feedforward signal generation block 20, the valve opening signal of the three-way valve 7 passes through two systems of dead time elements 21 and 22, and is synthesized by combining them. Enter device 23. The dead time is set by subtracting the response time of the three-way valve 7 from the dead time of the pipe. Since the response of the three-way valve 7 is different when the valve is opened and when it is closed, the dead time element 2
I have it in 1, 22. The synthesizer 23 determines whether the signals from the dead time elements 21 and 22 are in the opening direction or the closing direction of the three-way valve, and synthesizes the signals so that the three-way valve is not opened too much in the bypass direction. This feedforward signal is added to the PID calculation result of the controller 8. Then, the optimum valve opening of the three-way valve 7 is determined from the sum of the feedback signal and the feedforward signal.

FIG. 7 is a characteristic diagram of the control device of the present invention corresponding to the characteristic diagram shown in FIG. 10 of the conventional example. In this figure, at time t2, the operator uses 3 of the hot water utilization equipment 4 in order to operate the hot water utilization equipment 4 from the stopped state.
The one-way valve 5 is opened, but at this time, the heat source water absorption facility 4 absorbs the heat quantity of the heat source water.
It is necessary to prevent the surplus amount of heat that had been released to the outside from being released.

Therefore, the amount of heat generated from the engine 2
A heat quantity difference from the absorbed heat quantity obtained by the polygonal line function 18 representing the valve opening-absorption heat quantity characteristic of the hot water utilization equipment 4 is obtained. The difference in the amount of heat is the amount of heat released by the radiator 6. Next, the valve opening degree is calculated from the released heat amount using a polygonal line function 19 indicating the emission heat amount-valve opening degree characteristic of the heat radiation system. The value is input to the feedforward signal generation block 20,
The valve signal takes into account the pipe length and the dead time suitable for the three-way valve 7. By adding this as a feedforward value to the feedback signal from the controller 8, the optimum valve opening can be obtained.

In the conventional control in which no dead time is added, the three-way valve 7 is immediately operated by feedforward, so that the high temperature heat source water remaining in the pipe is sent to the engine as it is. By adding an appropriate dead time, the three-way valve 7 is operated in accordance with the decrease in the temperature of the heat source water in the pipe. Therefore, the amount of heat released by the radiator 6 is reduced by the hot water utilization equipment 4
Balance with the increase in the amount of heat used. As a result, a constant engine inlet temperature is obtained as shown in FIG.

In the control device according to the present invention, normally, the valve opening degree of the three-way valve 7 is optimally determined by the feedforward control in consideration of the dead time, and the engine inlet temperature is kept constant. The error of the feedforward line function,
The correction is performed by the feedback control only when the engine inlet temperature changes due to the disturbance caused by the change in the engine power generation amount. The detection of the valve opening of the heat radiation system is generally performed by a potentiometer, and there is no detection delay. Therefore, the feedforward control in consideration of the dead time enables appropriate response control.

As described above, according to the present embodiment, by controlling the valve 7 of the radiator 6 by incorporating the feedforward control in consideration of the dead time, the engine outlet temperature is controlled to be constant and the engine generated heat amount. If it is considered to be constant, the engine inlet temperature can also be kept constant, and since a function for three-way valve control is automatically generated according to the season,
Maintenance will be easier and system reliability and efficiency of hot water utilization equipment will be improved.

Further, in the example shown in FIG. 6, the dead time in the opening direction and the dead time in the closing direction of the three-way valve 7 are set to different values, but the characteristic of the three-way valve 7 opens. The same effect can be obtained with one dead time circuit as long as the direction and the closing direction are the same.

FIG. 8 is a control block diagram of a cogeneration system according to another embodiment of the present invention (corresponding to claims 1 to 10). In the present embodiment, the amount of heat generated by the engine 2 is calculated by multiplying the temperature difference detected by the temperature sensors 9 and 27 by the flow rate, instead of the arithmetic unit 12 that calculates the amount of heat generated by the engine in the embodiment of FIG. Arithmetic unit 17
Since the other points are the same and the other components are the same, the same components as those in the embodiment of FIG.

In this embodiment, the rated heat generation amount is set to the engine 2
However, when the load of the generator 1 changes, the engine generated heat amount calculated from the temperature difference between the inlet temperature and the outlet temperature of the engine 2 and the flow rate is used as in the present embodiment. Even if feedforward control is performed,
The inlet temperature of the engine 2 can always be controlled to be constant. The method of calculating the calorific value of the engine is not limited to this, but may be a method of calculating from a generator output in a predetermined pattern.

In the embodiment of FIG. 1, the valve opening of the three-way valve 5 is used as the source signal of the feedforward signal.
However, the present invention is not limited to this, and the same effect can be obtained by detecting the outlet temperature of the three-way valve 5 and generating a feedforward signal from that signal. Further, since the difference between the engine outlet temperature and the outlet temperature of the three-way valve 5 is proportional to the amount of heat used in the hot water utilization facility, the feedforward signal may be generated from this signal. Furthermore, in the embodiment of FIG. 1, a system having an exhaust gas boiler has been described. However, even in a system without an exhaust gas boiler, a system including a heat exchanger in an engine, or a system having a plurality of engines and heat utilization facilities, The present invention has the same effect as the above embodiment.

[0039]

As described above, the present invention (Claim 1)
According to claim 10), in the control system for detecting the heat source water temperature at the engine inlet and performing feedback control, the pipe and the heat radiating three-way system are used based on the heat quantity difference between the engine generated heat quantity and the absorbed heat quantity in the hot water utilization facility. By creating and incorporating a feedforward signal considering the dead time of the valve response, the valve opening of the radiator can be optimally controlled and the heat source water inlet temperature of the engine can be kept constant. Therefore, if the amount of heat generated by the engine is constant, the outlet temperature of the engine can also be maintained constant. In addition, since the function that determines the valve opening of the radiator three-way valve is generated as an appropriate function from changes in outside temperature and humidity, optimal control of the radiator three-way valve is automatic throughout the year. Yes, the engine inlet temperature can be kept constant throughout the year. In this way, by controlling the engine inlet temperature at a constant level, the reliability of the cogeneration system as a whole is improved, and because a control function is generated according to the season, optimum temperature control is possible throughout the year. It has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a cogeneration system according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram of a line function 18;

FIG. 3 is a block diagram of a function generator.

FIG. 4 is an input / output characteristic diagram of a function generator.

FIG. 5 is a characteristic diagram of a polygonal line function 19.

6 is a generation block diagram of the feedforward signal of FIG. 1. FIG.

FIG. 7 is a characteristic diagram of the control device of the present invention.

FIG. 8 is a control block diagram of a cogeneration system according to another embodiment of the present invention.

FIG. 9 is a control block diagram of a conventional co-generation system.

FIG. 10 is a characteristic diagram of a conventional control device, FIG. 10 (a) is a diagram showing a temperature change during feedback control,
FIG. 6B is a diagram showing a temperature change when the feedforward control is incorporated.

[Explanation of symbols]

1. Power generation system 2. Engine 3. Exhaust gas boiler
4 ... Hot water utilization equipment, 5, 7 ... 3-way valve, 6 ... Radiator, 8 ...
Controller, 9, 24 ... temperature sensor, 11 ... pump,
12, 17 ... Arithmetic device, 13, 14, 15, 16 ... Pipes through which heat source water flows, 18 ... Line function for obtaining heat quantity from valve opening of heat radiation system, 19 ... Line function for finding valve opening from heat quantity, 20 ... Feedforward signal generation block, 21, 22 ... Dead time element, 23 ... Device for synthesizing signals and taking out necessary signal, 24 ... Function generator, 25 ... Temperature sensor, 26 ... Humidity sensor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F16K 11/00 F16K 11/00 C G05B 11/32 G05B 11/32 F 11/36 11/36 K G05D 23/19 G05D 23/19 J

Claims (10)

(57) [Claims] 1. A heat source water that flows through a system is heated by heat generated from an engine that drives a generator, and hot water utilization equipment that uses the heated heat source water and the amount of heat absorbed by the hot water utilization equipment are adjusted. A first three-way valve, a radiator that releases the amount of heat that could not be used in the hot water utilization facility, a second three-way valve that adjusts the amount of heat released by the radiator, the engine and the hot water utilization facility In the temperature control device of the co-generation system in which the heat source water is connected between each element of the heat radiator and the heat sink water, a temperature sensor for detecting the engine inlet temperature of the heat source water, and the engine inlet temperature detected by the temperature sensor. And a controller for performing feedback control by calculating a valve opening set value of the second three-way valve so that the temperature becomes a predetermined temperature, and hot water utilization equipment based on a valve opening signal of the first three-way valve. The calculated amount of heat used is calculated from the difference between the amount of heat used by the engine and the amount of heat generated by the engine, a valve opening command signal is calculated in a predetermined pattern, and the valve opening command signal is delayed by a predetermined dead time. A feed-forward signal is added to the valve opening set value of the controller, and the valve opening reference signal after addition is used to adjust the valve opening of the second three-way valve. Temperature control device. 2. The temperature control device for a cogeneration system according to claim 1, wherein the valve opening command signal is delayed by a predetermined dead time, the valve opening is increased, and the valve opening is reduced. A temperature control device for a co-generation system characterized by having different dead times. 3. The temperature control device for a co-generation system according to claim 1, wherein the amount of heat generated by the engine is calculated from the temperature difference between the inlet temperature and the outlet temperature of the engine and the flow rate. -Temperature control device for generation system. 4. The temperature control device for a cogeneration system according to claim 1, wherein the first
Instead of the valve opening signal of the three-way valve, a valve opening command signal is calculated from the temperature of the raw raw water at the outlet of the first three-way valve according to a predetermined function pattern. Temperature control device. 5. The temperature control device for a cogeneration system according to claim 1, wherein the first
Instead of the valve opening signal of the three-way valve, the valve opening command signal is calculated according to a predetermined function pattern from the difference between the heat source water outlet temperature of the engine and the outlet temperature of the first three-way valve. The temperature controller for the co-generation system. 6. The temperature control device for a cogeneration system according to claim 1, wherein the second
The temperature control device of the cogeneration system, wherein the function for determining the valve opening of the three-way valve is generated by a function generator with the outside air temperature and humidity as inputs. 7. The temperature control device for a cogeneration system according to any one of claims 1 to 6, wherein the engine includes an exhaust gas boiler device. 8. The temperature controller of the cogeneration system according to claim 1, wherein a plurality of the engines are provided and they are connected in parallel by piping. System temperature controller. 9. The temperature control device for a cogeneration system according to claim 1, wherein the engine includes a heat exchanger, and the heat source water exchanges heat from engine cooling water to obtain heat. A temperature control device for a cogeneration system, which is characterized in that 10. The temperature control device for a cogeneration system according to claim 1, wherein a plurality of the hot water utilization facilities and the first three-way valves are installed and are connected in series or in parallel. The temperature control device of the co-generation system characterized by the above.