KR101949743B1 - A combined heat and power generating system and A method for controlling the same - Google Patents

Abstract

A cogeneration system according to the present invention is a cogeneration system comprising: an engine using gas as fuel; a generator driven by the engine to produce electric power; an impeller connected to a turbine rotated by the exhaust gas of the engine, A turbocharger for supplying the exhaust gas to the turbocharger, an intake valve installed in a natural intake passage connected to the engine so as to be sucked into the engine without passing through the turbocharger, exhaust gas branched from a flow path into the turbocharger, And a control unit for controlling the engine, the intake valve, and the exhaust valve, wherein the control unit controls the engine, the intake valve, and the exhaust valve, When the number of revolutions of the engine is less than a predetermined value, the intake valve is opened, The exhaust gas is controlled so as to be discharged to the bypass flow.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cogeneration system and a control method thereof,

The present invention relates to a cogeneration system and a control method thereof.

A cogeneration system is a system that generates electricity from a generator by operating an engine with gas fuel, and converts the heat generated by the engine into hot water or the like to supply it to the customer.

In this cogeneration system, an air conditioner is connected to supply power and heat or hot water to the air conditioner.

The engine turns the generator to produce power. In addition, the electric power generated by the generator can be converted into commercial electric power converted from electric power, voltage, frequency and the like in the electric power converter and supplied to electric power consumers such as building or air conditioner.

The engine is controlled to follow the target engine speed according to the load applied thereto. When the load applied to the engine increases, the control unit changes the target rotational speed to a larger value and increases the amount of opening of the fuel valve or the like so as to operate the engine. As the load becomes smaller, the target engine speed decreases and accordingly the opening amount of the fuel valve or the like becomes smaller.

In order to improve the engine output, a turbocharger for supplying a high-pressure mixture to the exhaust gas output of the engine may be used as a supercharger that supplies the mixture to the engine at a higher pressure.

The engine having the turbo charger can improve the engine output in the high engine speed range but has a problem that the output is lower than the natural intake type engine which does not use the turbocharger in the low engine speed range.

As a conventional technique for solving such a problem, a Korean Registered Utility Model No. 20-0151137 discloses an intake apparatus for a turbocharged engine.

An intake apparatus for a turbocharged engine, which is used in an automobile, includes: a first intake system that constantly supplies air to an engine by an intake negative pressure of the engine regardless of driving conditions of the engine; And a second intake system opened to supply the engine with supercharging air in accordance with the turbocharger drive only in the high RPM operating range of the engine.

However, in the case of a low engine speed, the solenoid valve blocks the second intake system. In this case, since the exhaust gas always operates the turbocharger, there is no flow path through which the air compressed by the impeller of the turbocharger is discharged. So that the output of the engine is lowered.

In addition, it is impossible to quantitatively adjust the amount of naturally aspirated air, and the engine efficiency may be deteriorated due to the difference between the intake air amount and the exhaust amount.

An object of the present invention is to provide a cogeneration system and a control method thereof that can improve the engine output even when the engine speed is high and the engine speed is low in a cogeneration system including an engine having a turbocharger .

According to an aspect of the present invention, there is provided a cogeneration system including an engine using gas as fuel, a generator driven by the engine to generate electric power, and an impeller connected to a turbine rotated by the exhaust gas of the engine, A turbocharger for compressing and supplying a mixture to be sucked into the turbocharger, an intake valve installed in a natural intake passage connected to the mixer to be sucked into the engine without passing through the turbocharger, A control valve for controlling the engine, the intake valve, and the exhaust valve, and a control valve for controlling the engine, the intake valve, and the exhaust valve, Wherein when the number of revolutions of the engine is less than a predetermined value, Opening the probe wherein the exhaust valve is controlled such that the exhaust gas discharged to the bypass flow.

The control unit closes the intake valve and controls the exhaust valve to pass the exhaust gas through the turbocharger when the engine speed becomes faster than the first rotation speed value.

And the control unit controls the exhaust valve so that the exhaust gas is exhausted to the bypass flow passage when the engine rotation speed becomes slower than the second rotation speed value.

It is preferable that the intake valve and the exhaust valve are step valves whose opening amount is adjusted by 5 to 15% per second.

And the second rotational speed value is greater than the first rotational speed value by 50 rpm.

It is preferable that the first rotation number value is 1300 to 1500 rpm and the second rotation number value is 1400 to 1500 rpm.

A control method of a cogeneration system according to the present invention is a control method for a cogeneration system including an engine and a generator equipped with a turbocharger. The control method includes a step of controlling the engine so as to follow a target revolution speed, Opening the intake valve such that the mixture injected into the engine does not pass through the turbocharger when the number of revolutions of the engine is equal to or less than a predetermined value and discharging the exhaust gas through the bypass passage without passing through the turbocharger And controlling the exhaust valve to control the exhaust valve.

When the engine speed is increased to a value equal to or higher than the first rotational speed value, the intake valve is closed and the exhaust valve is controlled so that all of the exhaust gas passes through the turbocharger.

When the engine rotation speed is slower than the second rotation speed value, the intake valve is opened and the exhaust valve is controlled so that all of the exhaust gas is discharged to the bypass passage.

Preferably, the opening amount of the intake valve and the exhaust valve is controlled by 5 to 15% per second.

And the second rotational speed value is greater than the first rotational speed value by 50 rpm.

It is preferable that the first rotation number value is 1300 to 1500 rpm and the second rotation number value is 1400 to 1500 rpm.

According to the cogeneration system of the present invention and the control method thereof, when the engine is operated at high speed in the cogeneration system including the engine having the turbocharger, the turbocharger supercharges the mixer to a high pressure to improve the engine output Of course, at low-speed operation, the engine output can be improved over the entire range of the engine rotation speed by bypassing the mixer in the engine by the natural intake system and bypassing the exhaust gas through the turbocharger.

1 is a conceptual diagram schematically showing an example of a cogeneration system.
2 is a block diagram showing a sensor and a valve connected to the control unit.
3 is a schematic view showing the intake and exhaust flow paths of the engine according to the present invention and its connection relationship.
4 is a graph showing a comparison between torques according to engine speeds of a turbocharger applied engine and a natural-intake engine.
5 is a schematic view showing intake and exhaust flows when a turbocharger is used in high-speed rotation.
6 is a schematic view showing intake and exhaust flows when the turbocharger is not used at low-speed rotation.
7 is a flowchart showing a control method according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram schematically showing an example of a cogeneration system.

The cogeneration system 100 refers to a system that generates electricity from a generator by operating an engine with gas fuel, converts heat generated by the engine into hot water or the like, and supplies the heat to the customer.

In the cogeneration system 100, an air conditioner is connected to supply power, heat, or hot water to the air conditioner.

The gaseous fuel can be supplied by the zero governor 12 while maintaining a constant outlet pressure regardless of the shape of the inlet input or the change in flow rate. The zero governor 12 is capable of obtaining a stable outlet pressure over a wide range and has a function of adjusting the pressure of the gaseous fuel supplied to the engine to almost constant at atmospheric pressure. In addition, the zero governor 12 is provided with two solenoid valves to shut off the supplied fuel.

The air can be filtered and supplied with clean air through an air cleaner 14. The air cleaner 14 can block the mixing of moisture and oil in the form of dust and mist using external air supplied to the engine as a filter.

The gas fuel and the air supplied as described above can be sucked into the engine by a mixer having a constant mixture ratio of air and fuel by a mixer (16).

Between the zero governor 12 and the mixer 16, a fuel valve 13 for regulating the flow rate of fuel flowing into the mixer 16 may be provided.

A turbocharger 20 can compress the mixer to a high temperature and high pressure state. The turbocharger 20 is a device that rotates the turbine by the force of the exhaust gas, compresses the intake air by its rotational force, and sends the compressed air to the cylinder of the engine to increase the output.

The turbocharger 20 is a combination of a turbine and a supercharger. The turbocharger 20 is composed of a turbine and an air compressor connected directly to the turbine. The turbine wheel is rotated by the energy of the exhaust gas The air sucked by the air compressor can be compressed and sent to the cylinder.

The turbocharger 20 has a structure in which a turbine wheel in which a blade is installed and an impeller of an air compressor are connected to one shaft and each surrounds the housing, and can be disposed near the exhaust manifold of the engine.

The mixer is cooled by the intercooler 25 and then introduced into the engine 30 through the intake manifold 32 because the temperature of the mixture is compressed by the turbocharger 20. [ The intercooler 25 can cool the mixer to increase the density, thereby increasing the absolute amount of the mixer introduced into the engine and improving the engine output.

The intercooler 25 may comprise an air-cooled heat exchanger that cools with air or a water-cooled heat exchange path that cools with water. The water-cooled intercooler can use cooling water as a medium, and it has a separate heat exchanger and pump to discard the calories from the compressed mixer to the outside.

An ETC valve (Electronic Throttle Control Valve) 29 is provided at the inlet side of the intake manifold 32 to regulate the amount of the mixer introduced into the engine. When a large number of mixers are supplied, the engine output becomes large.

The control unit 110 controls the operation of the engine 30 by adjusting the opening of the fuel valve 13 and the opening of the ETC valve 29. As the opening degree of the fuel valve 13 and the opening degree of the ETC valve 29 become larger, the engine speed will increase.

The engine 30 is an internal combustion engine that operates the mixer introduced through the intake manifold 32 through four strokes of suction, compression, explosion, and exhaust.

Exhaust gas generated as the engine 30 is operated is discharged through the exhaust manifold 34, at which time the impeller of the turbocharger 20 is rotated.

The engine 30 rotates the generator 40 to produce electric power. To this end, a belt may be connected between a pulley 36 provided at one end of the rotating shaft of the engine 30 and a pulley 46 provided at one end of the rotating shaft of the generator 40.

The pulley 36 of the engine 30 and the pulley 46 of the generator 40 may be provided so that the rotation ratio thereof is approximately 1: 3. That is, when the engine 30 rotates at 1000 rpm, the generator 40 can rotate at about 3000 rpm.

The power generated by the generator 40 may be converted into a commercial power converted from a current, a voltage, a frequency, etc. in the power converter 90 and supplied to a power consumer such as a building or an air conditioner.

On the other hand, since the engine 30 generates considerable heat during operation by gas combustion, it circulates the cooling water and performs heat exchange to absorb the heat of high temperature generated in the engine.

In the automobile, the radiator is installed in the cooling water circulation flow path to discard all of the waste heat of the engine. In the cogeneration system 100, however, the heat generated by the engine can be absorbed to generate hot water.

To this end, a hot water heat exchanger (50) is provided in the cooling water circulation channel so that heat is exchanged between water supplied separately from the cooling water so that the water receives heat from the high temperature cooling water.

The hot water generated by the hot water heat exchanger (50) is stored in the hot water storage tank (51) and can be supplied to hot water consumers such as buildings.

In the case where hot water is not used in the hot water consumer, water is not supplied to the hot water heat exchanger 50, and the temperature of the cooling water rises. To prevent this, a separate heat radiator 70 is installed, You can throw away.

The radiator 70 dissipates heat by exchanging heat with the air by means of a plurality of fins, and the heat dissipating fan 72 may be provided to accelerate heat dissipation.

The cooling water flow path from the engine 30 is branched into the hot water heat exchanger 50 and the radiator 70 and a three-way valve 53 is provided at the branch point to control the flow direction of the cooling water according to the situation . The cooling water can be sent only to the hot water heat exchanger 50 or only to the radiator 70 by the three-way valve 53 or can be divided into the hot water heat exchanger 50 and the radiator 70 at a predetermined ratio depending on the situation.

Way valve 53 and radiating from the radiator 70 can be combined with the cooling water that has passed through the three-way valve 53 and passed through the hot water heat exchanger 50 and then introduced into the engine 30.

The cooling water circulating passage is provided with a cooling water pump 55 to adjust the flow rate of the cooling water. This cooling water pump 55 can be installed downstream of the hot water heat exchanger 50 and the radiator 70 and upstream of the engine 30 in the cooling water circulation flow path.

On the other hand, the exhaust gas flowing through the exhaust manifold 34 of the engine 30 operates the turbocharger 20 described above. However, the exhaust gas heat exchanger 60 may be provided to recover the waste heat of the exhaust gas. have.

The exhaust gas heat exchanger 60 is arranged between the cooling water pump 55 and the upstream side of the engine 30 in the cooling water circulating flow passage and can be configured to exchange heat between the exhaust gas discharged through the turbocharger 20 and the cooling water . The exhaust heat of the exhaust gas can be recovered through the exhaust gas heat exchanger (60).

The cooling water is heated to some extent while flowing through the exhaust gas heat exchanger 60 and flows into the engine 30 in a lukewarm state, but the cooling water can sufficiently cool the engine 30.

Exhausted gas passing through the exhaust gas heat exchanger 60 passes through the muffler 80 and the exhaust side noise of the engine can be reduced by the muffler 80. [

The exhaust gas that has passed through the muffler 80 can be discharged to the outside after passing through the drain filter 85. The drain filter 85 has a built-in hydride filter for purifying the condensed water generated in the muffler 80, the exhaust gas line, etc., so that the acidic condensed water can be purified and neutralized and flow out to the outside.

2 is a block diagram showing a sensor and a valve connected to the control unit.

The control unit 110 controls the operation of the cogeneration system including the engine and various sensors and valves.

In particular, the engine is provided with an engine speed sensor 120 to calculate the revolution speed (rpm) of the engine per minute.

In addition, a MAP sensor (Manifold Absolute Pressure Sensor) 130 for measuring the suction pressure is provided in the intake manifold 32, and the magnitude of the corresponding load can be relatively calculated from the suction pressure of the mixer flowing into the engine.

Generally, as the flow rate of the mixture of the fuel and the air is increased, the number of revolutions of the engine increases and thus the output, that is, the power generation amount increases.

A fuel valve 13 is provided at the inlet side of the mixer 16 to regulate the supply amount of the gaseous fuel to be mixed with the air. When a large amount of gaseous fuel is supplied, the mixing ratio of the air-fuel mixture becomes large.

Further, an ETC valve (Electronic Throttle Control Valve) 29 is provided at the inlet side of the intake manifold 32 to adjust the amount of the mixer introduced into the engine. When a large number of mixers are supplied, the engine output becomes large.

The control unit 110 controls the operation of the engine 30 by adjusting the opening of the fuel valve 13 and the opening of the ETC valve 29. As the opening degree of the fuel valve 13 and the opening degree of the ETC valve 29 become larger, the engine speed will increase.

3 is a schematic view showing the intake and exhaust flow paths of the engine according to the present invention and its connection relationship.

The turbocharger 20 is connected to the cylinder of the engine 30 by a mixer supply line and an exhaust gas discharge line.

The turbocharger 20 includes a turbine 21 rotated by the exhaust gas discharged from the engine, an impeller 23 compressing the mixer and sending it to the engine, and a turbine 21 connected to the impeller 23, (Not shown).

The exhaust gas discharged from the cylinder of the engine 30 is discharged to the outside through the muffler 80 after rotating the turbine 21.

The mixer that is introduced into the turbocharger 20 and compressed by the impeller 23 is cooled in the intercooler 25 and then introduced into the engine 30 cylinder through the intake manifold 32 and the intake valve.

3 differs from the structure of FIG. 1 in that a natural intake passage and an intake valve 140 for naturally sucking a mixer in a mixer supply line are provided, and a muffler 80 A bypass valve 160 directly connected to the turbocharger 20, and an exhaust valve 150 at a branch point between the flow path to the turbocharger 20 and the bypass flow path.

The natural intake passage is connected so that the mixer is compressed by the turbocharger 20 and cooled by the intercooler 25 and naturally sucked by the negative pressure of the engine cylinder into the intake passage flowing into the engine 30. [

That is, the mixer flow path is connected from the mixer 16 to the turbocharger 20, and is also connected to the natural intake flow path.

An intake valve 140 is provided in the natural intake flow passage to open and close the natural intake flow passage.

It is preferable that the intake valve 140 is provided as a step valve so that the amount of opening of the natural intake passage can be adjusted in stages.

The exhaust gas discharge line is branched into a flow path through the turbocharger 20 and a bypass flow path 160 not through the turbocharger 20 and the two flow paths can be rejoined before the muffler 80. [

An exhaust valve 150 is provided at a branch point between the flow path passing through the turbocharger 20 and the bypass flow path 160 to adjust the amount of opening to the two flow paths. That is, the exhaust valve 150 may allow all of the exhaust gas to pass through the turbocharger 20, bypass only the bypass flow path 160, or flow at a predetermined ratio with two flow paths.

3, a part of the exhaust gas is compressed by the turbocharger 20 and supercharged by the turbocharger 20, and the rest of the exhaust gas is sucked by the natural intake system. A portion of the exhaust gas passes through the turbocharger 20, And then discharged to the discharge port 160.

4 is a graph showing a comparison between torques according to engine speeds of a turbocharger applied engine and a natural-intake engine.

In the case of a natural intake engine without a turbo charger, the torque (Nm) tends to increase gradually as the engine speed (rpm) increases.

In the case of an engine equipped with a turbocharger, the torque increases sharply as the engine speed rpm increases, but the torque tends to decrease rather slowly as the engine speed rises above a predetermined value.

As shown in Fig. 4, at the predetermined engine speed, there is an output crossing point at which the torque of the turbocharger application engine starts to become larger than the torque of the naturally-aspirated engine.

Therefore, if the engine speed is lower than the output crossing point and the engine speed is lower than the output crossing point, the engine output will be maximized if the engine is operated in the turbocharger mode.

5 is a schematic view showing intake and exhaust flows when a turbocharger is used in high-speed rotation.

When the engine is rotated at a high engine speed, the exhaust valve 150 is opened only to the turbocharger 20 side by 100% so that all the exhaust gas passes through the turbocharger 20 and rotates the turbine 21.

At the same time, the intake valve 140 is completely closed so that the mixer is sucked into the engine after being compressed by the turbocharger 20.

6 is a schematic view showing intake and exhaust flows when the turbocharger is not used at low-speed rotation.

When the engine is rotated at a low engine speed, the exhaust valve 150 is opened only toward the bypass flow path 160 so that all the exhaust gas is discharged without passing through the turbocharger 20.

At the same time, the intake valve 140 is fully opened so that the mixer is not compressed by the turbocharger 20 but is sucked into the engine by the negative pressure of the engine cylinder in a naturally aspirated manner.

Hereinafter, a control method according to the present invention will be described with reference to FIG.

First, the engine is normally operated to follow the target engine speed corresponding to the external load by operating the engine (S10).

When the load fluctuation is small within a predetermined range, it can be seen that the load and the target engine speed are accordingly fixed. At this time, the variation range of the engine speed is also small and the normal state is reached can do.

The engine normal control means that the load fluctuation is eliminated and the engine rotational speed is stabilized by the target rotational speed following control.

Then, when the load is changed, the engine target rotation speed is changed corresponding thereto (S20).

When the target engine speed is changed, the turbocharger variable control is checked to check whether the turbocharger is used or not (S30).

When the turbocharger variable control is entered, it is checked whether or not the turbocharger is currently used (S40). If the current turbocharger is used, the engine speed is equal to or greater than a predetermined value. If the current turbocharger is not used, the engine speed will be equal to or less than the predetermined value.

In step S50, the engine is rotated at a low speed to suck the mixer into the engine in a natural intake mode, and the turbocharger is not used, and it is determined whether or not the engine speed becomes greater than or equal to the first speed value.

The first rotational speed value can be set at 1400 rpm because the output cross point is about 1400 rpm in Fig. 4, but the first rotational speed value can be set to 1300 to 1500 rpm since it may vary depending on the cogeneration system.

The intake valve 140 is closed to 0% and the exhaust valve 150 is closed to the turbocharger 20 by adjusting the opening amount of the intake valve 140 and the exhaust valve 150, (S70).

The intake valve 140 and the exhaust valve 150 are step valves which are controlled by the amount of opening 5 to 15% per second so that they are finally opened completely or completely closed.

If the turbocharger is currently being used, it is determined that the engine rotates at a high speed and the engine speed decreases and decreases to the second speed value or less (S60).

The second rotation speed value may be set to about 1400 rpm as the first rotation speed value, but it is preferably set to about 1450 rpm which is about 50 rpm higher than the first rotation speed value.

This second rotational speed value may also be set to 1400 to 1500 rpm since it may vary depending on the cogeneration system.

The reason why the second rotational speed value is set to be larger than the first rotational speed value is that the engine should be changed to the natural intake mode when the engine rotates at high speed and changes to low speed. This is because the connection state change is delayed.

Thus, when the engine speed changes from high speed to low speed, the valve opening amount adjustment control is started earlier in a natural intake mode at a higher engine speed than in the opposite case so that the change in the state of the oil passage connection at the output intersection point can be completed can do.

The intake valve 140 is opened to 1000% and the exhaust valve 150 is opened to the bypass flow passage 160 by adjusting the opening amounts of the intake valve 140 and the exhaust valve 150, (S70).

Next, it is checked whether the intake valve 140 and the exhaust valve 150 are opened or closed, and it is checked whether the opening amount of each valve is completely opened or completely closed (S80).

If the valve opening and closing is not completed, the valve opening amount adjustment control is continued, and if the valve opening and closing is completed, the turbocharger variable control is ended and the engine normal control (S10) is returned.

According to the present invention, the mixer compressed by the turbocharger is sucked during high-speed rotation of the engine, and the mixer is sucked by the natural intake system without using a turbocharger at low speed rotation. Lt; / RTI >

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Changes will be possible.

12: zero governor 13: fuel valve
14: air cleaner 16: mixer
20: Turbocharger 21: Turbine
22: rotating shaft 23: impeller
29: ETC valve
30: engine 40: generator
50: hot water heat exchanger 60: exhaust gas heat exchanger
70: Radiator 80: muffler
90: power converter 100: cogeneration device
110: control unit 120: engine speed sensor
130: MAP sensor 140: intake valve
150: exhaust valve 160: bypass passage

Claims (12)

An engine using gas as fuel;
A generator driven by the engine to produce electric power;
A turbocharger connected to an exhaust gas discharge line of the engine to compress and supply a turbine rotated by exhaust gas and a mixer in which an impeller connected to the turbine is sucked into the engine;
An intake valve provided in a natural intake passage connected to the mixer so as to be sucked into the engine without passing through the turbocharger;
A bypass flow path connected to the exhaust gas discharge line and branched from a flow path through which the exhaust gas flows into the turbocharger to discharge the exhaust gas without passing through the turbocharger;
An exhaust valve installed at a branch point between a flow path through which the exhaust gas flows into the turbocharger and the bypass flow path; And
And a control unit for controlling the engine, the intake valve, and the exhaust valve,
Wherein the control unit is a value having a certain range including an engine speed corresponding to an output crossing point at which the torque of the engine due to the engine speed starts to become larger than the torque of the natural intake engine without the turbocharger The exhaust valve opens the intake valve and controls the exhaust gas to be discharged to the bypass flow passage when the second rotational speed is equal to or lower than the second rotational speed,
Wherein the control unit closes the intake valve and controls the exhaust valve to pass the exhaust gas through the turbocharger when the number of revolutions of the engine is smaller than the second number of revolutions and equal to or greater than a first number of revolutions Cogeneration system. delete The method according to claim 1,
Wherein the first rotation speed and the second rotation speed are set in accordance with a delay in change of the connection state of the bypass passage due to the opening degree change of the exhaust valve. The method according to claim 1,
Wherein the intake valve and the exhaust valve are step valves whose opening amount is adjusted by 5 to 15% per second. The method according to claim 1,
Wherein the second rotation speed is 50 rpm greater than the first rotation speed. The method according to claim 1,
Wherein the first rotation number is 1300 to 1500 rpm and the second rotation number is 1400 to 1500 rpm. An engine connected to an exhaust gas discharge line of the engine and having a turbine rotated by exhaust gas and a turbocharger for compressing and supplying a mixer in which the impeller connected to the turbine is sucked into the engine, An intake valve disposed in a natural intake passage connected to the engine so as to be sucked into the engine without passing through the turbocharger, and an exhaust valve connected to the exhaust gas discharge line, branched from a flow path through which the exhaust gas flows into the turbocharger, And an exhaust valve installed at a branch point between a flow path through which the exhaust gas flows into the turbocharger and the bypass flow path, the control method comprising the steps of:
Controlling operation of the engine so as to follow the target rotation speed;
Changing a target engine speed according to a load change;
Which is a value having a certain range including an engine rotation number corresponding to an output crossing point at which the engine rotation speed starts to become larger than the torque of the engine that is not provided with the turbocharger by the engine rotation speed, Opening the intake valve and controlling the exhaust valve to discharge the exhaust gas to the bypass flow passage; And
Closing the intake valve and controlling the exhaust valve to pass all of the exhaust gas through the turbocharger when the engine speed is equal to or higher than a first speed number which is a value having a constant range smaller than the second rotation speed And a control method of the cogeneration system. delete 8. The method of claim 7,
Wherein the first rotation speed and the second rotation speed are set in accordance with a delay in a change in the connection state of the bypass passage due to a change in opening degree of the exhaust valve. 8. The method of claim 7,
And the opening amount of the intake valve and the exhaust valve is adjusted by 5 to 15% per second. 8. The method of claim 7,
Wherein the second rotation speed is 50 rpm greater than the first rotation speed. 8. The method of claim 7,
Wherein the first rotation number is 1300 to 1500 rpm and the second rotation number is 1400 to 1500 rpm.

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