KR101915990B1 - A combined heat and power generating system and A method for controlling the same - Google Patents

Abstract

A cogeneration system of the present invention comprises an engine using gas as fuel, a generator driven by the engine to produce electric power, a turbocharger operated by the exhaust gas of the engine to compress the mixer and supply it to the engine, And a controller for controlling the engine and the turbocharger, wherein the controller performs the turbocharger protection control in which when the engine stop signal is generated during normal engine operation, the engine is not stopped immediately but operated at a low engine speed for a predetermined time.

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.

To increase the output of the engine, a turbocharger can be connected to compress the mixer and suck it into the engine. The turbocharger compresses the mixer by rotating the turbine with the force of the exhaust gas and rotating the impeller coaxially connected thereto.

The engine burns the mixer in the cylinder, and when the explosive force pushes the piston, the crankshaft rotates to generate the rotational force.

Since the engine has relatively sliding parts such as a piston reciprocating in the cylinder and a crankshaft rotating, the engine cylinder is supplied with engine oil to lubricate between the parts.

The turbocharger is also supplied with engine oil because the turbine and impeller provided on both sides of the rotary shaft rotate.

An engine equipped with a turbocharger generates more heat than an engine without a turbo charger, so that suddenly turning off the engine may cause the engine to overheat.

The turbo charger rotates the impeller at 500,000 to 200,000 rpm during normal operation, and the bearing area is maintained at a very high temperature, so that the engine oil in the bearing seal area may be slightly carbonized. This is an inevitable part for high output using turbocharger, but since the amount of engine oil to be carbonized is very small, it does not have a big influence on engine oil replacement cycle.

If the engine and the turbocharger are driven to rotate at a high speed in response to a high load and immediately turn off the engine, the engine oil may not be supplied to the turbocharger, which may adversely affect the turbocharger bearing portion.

Therefore, in the case of stopping the engine, particularly at a high load, it is necessary to cool the turbocharger by supplying engine oil to the engine and the turbocharger by operating the engine at a low engine revolution for a predetermined time without immediately stopping the engine.

However, when the engine is operated at a low engine speed before stopping the engine, there is no standard for judging whether the engine has been operated sufficiently for protecting the turbocharger, so that idling can not be efficiently performed before stopping the engine.

The present invention provides a turbocharger protection control capable of supplying and cooling engine oil to and from the engine and the turbocharger by operating the engine at a low rotation speed without stopping immediately when the engine is stopped during normal operation. And to provide a cogeneration system capable of stopping the engine safely after precisely determining whether or not the cogeneration system has been sufficiently performed, and a control method thereof.

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, a compressor driven by the exhaust gas of the engine to compress the mixer, And a controller for controlling the engine and the turbocharger, wherein the controller is configured to perform a turbocharger protection control in which when the engine stop signal is generated during normal engine operation, .

Preferably, the controller controls the turbocharger when the engine speed, the suction pressure, and the engine oil temperature are equal to or greater than a predetermined value, respectively, and otherwise stops the engine.

Preferably, the control unit performs turbocharger protection control when the number of revolutions of the engine is 1500 rpm or more, the suction pressure is 900 hPa or more, and the engine oil temperature is 90 ° C or more.

During the turbocharger protection control, the engine is preferably operated at a target rotational speed of 900 to 1100 rpm.

In the turbocharger protection control, it is preferable to operate the heat dissipation fan, the cooling water pump, and the oil pump.

After the turbocharger protection control, it is preferable to stop the engine when the number of revolutions of the engine is less than the predetermined value, the engine oil temperature is less than the predetermined temperature, and the predetermined time or more elapses after entering the turbocharger protection control.

Preferably, the control unit stops the engine when the number of revolutions of the engine is less than 1100 rpm, the engine oil temperature is less than 90 캜, and more than two minutes have elapsed after entering the turbocharger protection control.

A control method of a cogeneration system according to an embodiment of the present invention includes a step of performing normal operation control so as to follow a target engine speed of an engine, a step of receiving an engine stop signal, a step of receiving an engine stop signal, , Performing turbocharger protection control for operating the engine at a low engine speed for a predetermined time without immediately stopping the engine if the engine speed, the suction pressure, and the engine oil temperature are respectively equal to or greater than a predetermined value, Stopping the engine when the engine speed is less than the predetermined value, the engine oil temperature is lower than the predetermined temperature, and the predetermined time has elapsed since the entry into the turbocharger protection control.

It is preferable that the step of determining the engine speed, the suction pressure and the engine oil temperature determine that the turbocharger protection control is necessary when the engine speed is 1500 rpm or more, the suction pressure is 900 hPa or more, and the engine oil temperature is 90 캜 or more.

In the turbocharger protection control step, it is preferable that the engine is operated at a target rotational speed of 900 to 1100 rpm to operate the heat radiating fan, the cooling water pump, and the oil pump.

After the turbocharger protection control, it is preferable to stop the engine when the number of revolutions of the engine is less than the predetermined value, the engine oil temperature is less than the predetermined temperature, and the predetermined time or more elapses after entering the turbocharger protection control.

After the turbocharger protection control, it is preferable to stop the engine when the engine speed is less than 1100 rpm, the engine oil temperature is less than 90 DEG C, and more than two minutes have elapsed after entering the turbocharger protection control.

According to another aspect of the present invention, there is provided a control method for a cogeneration system, including: performing normal operation control so as to follow an engine at a target engine speed; emergency stopping an engine by receiving an engine emergency stop signal; A step of performing a turbocharger protection control for maintaining the engine stop when the system restart is impossible and for restarting the engine at a low engine speed for a predetermined time when the system can be restarted; And controlling the normal operation by connecting a load to the engine when the engine coolant temperature is lower than the predetermined temperature and the predetermined time or more has elapsed after entering the turbocharger protection control.

In the turbocharger protection control step, it is preferable that the engine is operated at a target rotation speed of 750 to 850 rpm to operate the heat radiating fan, the cooling water pump, and the oil pump.

When the engine oil temperature is less than 90 占 폚, the engine coolant temperature is less than 50 占 폚, and more than two minutes have elapsed after entering the turbocharger protection control, it is preferable to control the normal operation by connecting a load to the engine after the turbocharger protection control Do.

According to the cogeneration system of the present invention and the control method thereof, when the engine is stopped during normal operation and stopped, the engine can be operated at a low rotation speed without stopping to supply and cool the engine oil to the engine and the turbocharger The turbocharger protection control can be performed, and the engine can be safely stopped after determining whether or not the turbocharger protection control is sufficiently performed.

In addition, even when the engine is restarted after an emergency stop, the turbocharger protection control is performed so that the engine can be supplied and cooled to the engine and the turbocharger by operating the engine at a low rotation speed. The engine can be operated normally.

1 is a conceptual diagram schematically showing an example of a cogeneration system.
2 is a conceptual diagram showing the flow of the exhaust gas and the mixer through the engine and the turbocharger.
3 is a conceptual diagram showing the oil circulation flow through the engine and the turbocharger.
4 is a block diagram showing various sensors, valves and pumps connected to the control unit.
5 is a flowchart showing a control method of the cogeneration system when an engine stop signal is generated.
6 is a graph showing changes in engine speed when the turbocharger protection control is performed according to the control method of FIG.
7 is a flowchart showing a control method of the cogeneration system when an engine emergency stop signal is generated.
8 is a graph showing changes in engine speed when the turbocharger protection control is performed according to the control method of FIG.

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.

Fig. 2 is a conceptual view showing the flow of exhaust gas and a mixer through an engine and a turbocharger, and Fig. 3 is a conceptual diagram showing an oil circulation flow through an engine and a turbocharger.

The turbocharger 20 is connected to the cylinder 31 of the engine by an exhaust gas line and a mixer feed 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 through the exhaust valve of the engine cylinder 31 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 can be introduced into the engine cylinder 31 through the intake manifold 32 and the intake valve.

As shown in Fig. 3, the engine 30 may be supplied with engine oil as a lubricating oil through a circulating line.

An oil reservoir is provided at the lower part of the engine 30 and an oil pump 37 and an oil filter 38 are provided at one side so that the oil can be circulated inside the engine.

Further, a part of the engine oil is supplied to the turbocharger 20 through the oil supply line, and the oil from the turbocharger 20 can be returned to the engine reservoir through the oil return line.

When the engine 30 is operated, the oil pump 37 is also operated to lubricate the engine and the turbocharger 20 by supplying the engine oil.

4 is a block diagram showing various sensors, valves and pumps 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 load can be inversely 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.

As described above, when the engine 30 is operated, the control unit 110 operates the oil pump 37 to lubricate the engine 30 and the turbocharger 20 with the engine oil.

The engine 30 is provided with an engine oil temperature sensor 160 to sense the temperature of the engine oil. As the temperature of the engine oil increases, the controller 110 controls the rotation speed of the oil pump 37 more rapidly .

A cooling water temperature sensor 170 for measuring the temperature of the cooling water for cooling the engine 30 is provided to sense the cooling water temperature passing through the engine. As the cooling water temperature increases, the controller 110 controls the cooling water pump 55 The rotational speed can be controlled more quickly.

FIG. 5 is a flow chart showing a control method of the cogeneration system when an engine stop signal is generated. FIG. 6 is a graph showing changes in engine speed when the turbocharger protection control is performed while normal operation is being performed.

Hereinafter, a control method of the cogeneration system according to an embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG.

First, the engine normal operation control is performed at an engine target rotation speed of, for example, 2000 rpm (S10).

Then, an engine stop signal is generated (S15), and the control unit 110 can receive the signal. The engine stop signal may be a command input by the manager when it is no longer necessary to develop, or may be a signal that occurs automatically when the load connected to the system is dropped.

Then, it is determined whether to enter the turbocharger protection control without immediately stopping the engine (S20). That is, it is determined whether or not the engine speed, the suction pressure, and the engine oil temperature are respectively equal to or greater than a predetermined value, and the turbocharger protection control is performed in such a state.

Specifically, the control unit determines whether or not the engine rotational speed is 1500 rpm or more (S30), whether the suction pressure is 900 hPa or more (S40), and whether or not the engine oil temperature is 90 ° C or more (S50) To perform turbocharger protection control for a predetermined period of time.

In the case of the turbocharger protection control (S60), the target engine speed of the engine can be operated at 900 to 1100 rpm, preferably at 1000 rpm. Further, the heat radiating fan 72 and the cooling water pump 55 are operated to cool the engine, and the oil pump 37 is operated to supply engine oil to the engine 30 and the turbocharger 20.

Next, it is determined whether or not the turbocharger protection control can be terminated.

That is, after the turbocharger protection control, the engine is stopped when the engine revolution number is less than the predetermined value, the engine oil temperature is less than the predetermined temperature, and the predetermined time or more elapses after entering the turbocharger protection control.

Specifically, the control unit determines whether or not the engine rotational speed is less than 1100 rpm (S70), whether or not the engine oil temperature is less than 90 DEG C (S80), and whether or not two minutes have elapsed after entering the turbocharger protection control (S90) It is possible to judge that the engine oil is sufficiently supplied to the turbocharger if the conditions are satisfied, otherwise the turbocharger protection control is continued.

If it is determined that the turbocharger protection control is sufficiently performed, the engine is stopped (S100).

As shown in Fig. 6, when the engine is running at a target engine speed of 2000 rpm, the engine coolant pump ON, the engine oil pump ON, and the heat radiating fan are in the ON state. When entering the turbocharger protection control, the engine rotational speed drops to 1000 rpm, , The engine oil pump ON state and the heat radiation fan ON state are maintained.

When the turbocharger protection control is fully performed, the engine is stopped, so that the engine speed drops to 0 rpm soon. However, it is preferable that the engine oil pump and the heat dissipation fan are turned off after the engine speed becomes 0 rpm. This is because the engine oil needs to be supplied and dissipated while the engine is operating even at low engine speeds.

Further, it is preferable that the cooling water pump is turned off after a lapse of a predetermined time after the engine is completely stopped. This is because even after the engine is stopped, there is heat in the engine, so it is necessary to continue cooling for a predetermined time.

FIG. 7 is a flowchart showing a control method of the cogeneration system when an engine emergency stop signal is generated. FIG. 8 is a flowchart showing the control method of the cogeneration system when the engine emergency stop signal is generated. And Fig.

Hereinafter, a method of controlling the cogeneration system during an emergency stop during normal operation will be described with reference to FIGS. 7 and 8. FIG.

First, the engine normal operation control is performed at an engine target rotation speed of, for example, 2000 rpm (S110).

Then, an engine emergency stop signal is generated (S115), and the control unit 110 can receive the signal.

The emergency stop signal is generated in the cogeneration system and the engine emergency stop signal is received by the control unit 110 to stop the engine (S120).

The emergency situation generally refers to a case where the load drops or falls abruptly, but it may also include the case where the engine is overheated and the coolant temperature rises above a predetermined value or the engine speed rises above a predetermined value.

When the engine is stopped urgently, for example, the engine speed is 2000 rpm and can be rapidly braked to 0 rpm.

Since the emergency stop signal is generated in the emergency state, it is determined whether the system can be restarted (S130). If one of the components that make up the system is damaged and can not function, the system can not be restarted.

If it is determined that the system restart is impossible, the engine stop is maintained (S140), and measures such as replacing parts or repairing can be taken.

If the system restart is possible, the turbocharger protection control (S150) is performed in which the engine is operated at a low engine speed for a predetermined time.

In the turbocharger protection control, the engine is stopped at an emergency and the engine is started at a target rotation speed of 750 to 850 rpm and the heat radiating fan 72, the cooling water pump 55 and the oil pump 37 are operated.

In general, when the engine is stopped, the engine is stopped after lubrication by operating at about 1000 rpm in the turbocharger protection control. In order to make the engine ready for normal operation after the emergency stop, the engine is operated at about 800 rpm You can refuel the turbocharger enough.

Next, in order to judge whether or not the turbocharger protection control has been sufficiently performed, it is determined whether or not the engine oil temperature is lower than a predetermined temperature, whether the engine coolant temperature is lower than a predetermined temperature, and whether or not a predetermined time has elapsed after entering the turbocharger protection control .

Specifically, when the engine oil temperature is less than 90 占 폚 (S160) and the engine cooling water temperature is less than 50 占 폚 (S170) and more than two minutes elapse after entering the turbocharger protection control (S180), the turbocharger protection control is terminated .

Then, since the turbocharger is sufficiently provided with the restart operation, the normal operation control (S190) can be performed by connecting the load to the engine.

As shown in FIG. 8, when the engine is operated at a target rotation speed of about 2000 rpm, when the emergency stop signal is received, the engine speed suddenly decreases to 0 rpm. At this time, the cooling fan is turned off, State.

When the system is restartable to perform turbocharger protection control, the engine is operated at about 800 rpm, the heat dissipation fan is turned on, and the coolant pump and the engine oil pump remain on.

When the turbo charger lubrication is in a sufficient state, the load can be connected to the engine and the target rotation speed can be controlled to 2000 rpm.

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 29: ETC valve
30: Engine 37: Oil pump
40: generator 50: hot water heat exchanger
55: cooling water pump 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 160: Engine oil temperature sensor
170: Coolant temperature sensor

Claims (15)

delete delete delete delete delete delete delete delete delete delete delete delete Controlling the engine so as to follow the target revolution speed;
Receiving an engine emergency stop signal and urgently stopping the engine;
Determining whether the system is restartable;
Performing turbocharger protection control to maintain the engine stop when the system restart is impossible and to operate the engine at a low engine speed for a predetermined time when the system restart is possible; And
When the engine oil temperature is lower than the predetermined temperature, the engine coolant temperature is lower than the predetermined temperature, and the predetermined time or more has elapsed after entering the turbocharger protection control, the step of controlling the normal operation by connecting the load to the engine And a control unit for controlling the cogeneration system. 14. The method of claim 13,
Wherein in the turbocharger protection control step, the engine is operated at a target rotation speed of 750 to 850 rpm, and the heat radiating fan, the cooling water pump, and the oil pump are operated. 15. The method of claim 14,
When the engine oil temperature is less than 90 DEG C, the engine coolant temperature is less than 50 DEG C, and more than two minutes have elapsed after entering the turbocharger protection control, a load is connected to the engine to perform normal operation control after the turbocharger protection control And a control method of the cogeneration system.

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