KR101926135B1 - Method for controlling engine and engine generation system using the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine power generation system, and more particularly, to an engine control method capable of efficiently controlling an engine during power generation and a cogeneration system using the same. According to the present invention, there is provided a control method of an engine for driving a generator, the method comprising: performing engine speed following control for operating the engine at a target engine speed; Operating the engine according to an electronic throttle control (ETC) control cycle on the table set for each engine revolution number for the engine in a fixed load; Determining a fluctuation range of the engine speed; Adjusting the ETC control period according to the range of the variation width; And operating the engine according to the changed ETC control period.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of controlling an engine,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine power generation system, and more particularly, to an engine control method capable of efficiently controlling an engine during power generation and an engine power generation system using the same.

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 basically driven by four strokes such as suction / compression / explosion / exhaust. Even when the engine is operating steadily, the engine can not always be driven at the same engine speed due to incomplete combustion or the like, have.

However, in the case of the cogeneration power generator, the constant voltage control of the power converter causes the load on the engine side to change slightly, which may cause the hunting of the engine to become larger.

As described above, the engine speed decreases when the load is increased and the engine speed increases when the load is reduced, for a constantly irregularly varying load rather than a fixed load. As described above, in following the engine target rotational speed, the engine rotational speed has a hysteresis due to rotational inertia, and the engine rotational speed error may be continuously increased or decreased due to the effect of the hysteresis.

For example, when a load is applied when the engine speed drops, the engine speed can be further lowered. When the load is reduced, the engine speed is further increased, and the hunting of the engine speed may become larger due to the influence of the connected load.

Therefore, there is a demand for a method for controlling the hunting of the engine speed.

An object of the present invention is to provide an engine control method capable of minimizing variations in engine speed during power generation and an engine power generation system using the same.

According to a first aspect of the present invention, there is provided a control method of an engine for driving a generator, the method comprising: performing engine speed following control for operating an engine at a target engine speed; Operating the engine according to an electronic throttle control (ETC) control cycle on the table set for each engine revolution number for the engine in a fixed load; Determining a fluctuation range of the engine speed; Adjusting the ETC control period according to the range of the variation width; And operating the engine according to the changed ETC control period.

Here, the step of adjusting the ETC control period may include: delaying the ETC control period by a first time when the range of the fluctuation width is in the first range; And delaying the ETC control period by a second time smaller than the first time when the range of the variation width is in a second range larger than the first range.

At this time, it is possible to determine the manifold absolute pressure (MAP) of the engine together with the variation range of the engine speed.

At this time, when the range of the fluctuation width is in the first range, the ETC control period can be delayed by the first time only when the variation width of the intake air pressure is within 5 hPa.

When the fluctuation range is in the third range larger than the second range, the engine can be operated according to the ETC control period on the table.

In this case, the ETC control period may be shortened if the range of the fluctuation width is a fourth range larger than the third range.

Here, the ETC control period may be adjusted between 700 ms and 1200 ms.

At this time, the ETC control period may be adjusted in units of 100 ms.

Here, the step of determining the fluctuation range of the engine speed may be repeatedly performed at predetermined time intervals.

According to a second aspect of the present invention, there is provided an engine power generation system comprising: a generator; An engine connected to a drive shaft of the generator to drive the generator; And a controller for controlling the engine, wherein the controller performs engine speed follow-up control for operating the engine at the target engine speed, and controls the electronic throttle The engine control system according to any one of claims 1 to 3, wherein the engine is operated in accordance with a control (ETC) control cycle, the fluctuation range of the engine speed is determined, the ETC control period is adjusted according to the range of the fluctuation width, have.

Here, the ETC control period may be adjusted between 700 ms and 1200 ms.

Here, the controller may repeatedly perform the process of determining the variation range of the engine speed at a predetermined time interval.

The present invention has the following effects.

First, when the present invention is applied, the target engine speed follow-up performance can be greatly improved in the engine speed stabilizing region based on the variable control period of the ETC, and when the engine power generation control is performed based on this, Stable development is possible within 5%.

In the cogeneration system, when the thermal efficiency is controlled to the maximum, the temperature of the engine cooling water becomes very low, so that the load of the engine rises slightly, and the cooling water and the oil temperature are lowered, thereby increasing the mechanical friction.

Accordingly, even when the engine is operated in a stable manner due to the change of the operating characteristic in the engine control due to the increase of the mechanical friction against the existing operation, the hunting of the smile occurs in the corresponding situation. However, when the present invention is applied, will be.

1 is a conceptual diagram schematically showing an example of a cogeneration system to which the present invention can be applied.
2 is a graph showing the engine speed at the time of operation when the ETC control period is fixed at 1 second.
3 is a diagram illustrating an ETC control cycle table according to an embodiment of the present invention.
4 is a flowchart showing an engine control method of an engine power generation system according to an embodiment of the present invention.
5 is a graph illustrating a process of varying the ETC control period according to the engine speed according to an embodiment of the present invention.
FIG. 6 is a graph showing the engine speed at the time of operation when the variable ETC control period according to the embodiment of the present invention is applied.
7 is a graph showing an engine speed error rate according to a load variation when the embodiment of the present invention is applied.
FIGS. 8, 9 and 10 are graphs showing the target rotational speed tracking performance according to the present invention when the loads are 10 kW, 20 kW, and 30 kW, respectively.
11 is a block diagram briefly showing an essential part of an engine power generation system in which the present invention can be implemented.

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

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

1 is a conceptual diagram schematically showing an example of a cogeneration system to which the present invention can be applied.

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. The engine power generation system of the present invention can achieve such a cogeneration system 100.

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 controlling the pressure of the gaseous fuel supplied to the engine to be 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).

At the inlet side of the mixer 16, a fuel valve 13 is provided 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.

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 be constituted by an air-cooled heat exchanger or a water-cooled heat exchange path for cooling 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.

A throttle valve (not shown) may be provided between the intercooler 25 and the intake manifold 32 to adjust the amount of the mixed gas introduced into the engine 30. An electronic throttle control valve (ETC valve) is generally used as the throttle valve.

Further, the engine can be controlled with various control variables related to the control of the engine through a separate engine control unit (ECU) 31. For example, the ETC valve 38 and the control period of the valve can be controlled by the ECU 31. The ECU 31 may be controlled by a control unit 110 (see FIG. 11) that controls the entire engine power generation system.

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 makes one revolution, the generator 40 can rotate about three times.

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.

The engine 30 driven for cogeneration is basically driven by four strokes such as suction, compression, explosion, and exhaust. Even when the engine is operating stably, the engine 30 is always operated at the same engine speed due to incomplete combustion, The hunting of the engine speed may occur.

However, in the case of the engine power generation system, the load applied to the engine 30 side is slightly changed due to the constant voltage control of the power converter 90, so that the hunting of the engine 30 can be further increased.

As described above, the engine speed decreases when the load is increased and the engine speed increases when the load is reduced, for a constantly irregularly varying load rather than a fixed load. As described above, in following the engine target rotational speed, the engine rotational speed has a hysteresis due to rotational inertia, and the engine rotational speed error may be continuously increased or decreased due to the effect of the hysteresis.

For example, when a load is applied when the engine speed drops, the engine speed can be further lowered. When the load is reduced, the engine speed is further increased, and the hunting of the engine speed may become larger due to the influence of the connected load.

As one of the most influential factors among factors contributing to the control of the number of revolutions of the engine 30, there is a control cycle of electronic throttle control or electric throttle control (ETC) control , According to the usual control method so far, the ETC control period is fixed to 1 second according to all situations.

2 is a graph showing the engine speed at the time of operation when the ETC control period is fixed at 1 second.

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a control method and system capable of minimizing variations in engine speed through stabilization of electronic throttle control (ETC) in order to improve hunting of the engine speed described above.

The control cycle of the ETC can be varied in accordance with the number of revolutions of the engine and the amount of variation in the load, so that the target revolving speed follow-up performance of the engine can be improved, and accordingly the target engine revolutions can be quickly followed.

At this time, the ETC control period is set as a table for each engine revolution number area based on the unit of 200 RPM, the optimum position on the table for the current state of the engine is determined, and then the ETC control Period can be applied. This will be described in detail later.

Therefore, by applying such a variable ETC control period, it is possible to improve the follow-up of the engine speed at the time of load variation, and it is possible to prevent abrupt fluctuation of the engine speed.

The ETC control period can be variably applied based on the engine speed variation and the load variation.

In addition, when the number of revolutions of the engine is within a stabilization period within a certain range, the ETC control period can be increased to maintain the stabilized state of the engine control.

3 is a diagram illustrating an ETC control cycle table according to an embodiment of the present invention.

In applying the present invention, the ETC control period is set as a table for each engine revolution number area based on a unit of 200 RPM in terms of the engine revolution number, and an optimum position on the table with respect to the current revolution number of the engine is determined The ETC control period on this table can be applied as an initial value (default; default).

3, when the ETC control period is controlled to be slow at a low number of revolutions, the ETC control period is controlled at a low number of revolutions and when the ETC control period is controlled to be slow at a high number of revolutions, the target engine speed / current engine speed error rate The lowest stable area can be set. That is, it is possible to set the basic ETC control period according to the operation range of the engine based on this.

In the case of a normal emergency generator, since the operation region of the engine is operated only in the same region, the ETC control period is not varied but is used in the same manner.

However, in the case of the cogeneration system, since the power generation amount is usually varied, when the ETC control period is not varied, the engine speed and the load may cause a large difference in the target rotational speed follow-up.

In order to solve this problem, a fixed load of 10 kW is applied to the engine, the ETC control period is changed in units of 100 ms, the engine speed is changed in units of 200 RPM while the follow- The ETC control cycle table can be set as shown in FIG.

That is, such a table may be a table set for a fixed load. As described above, the table shown in FIG. 3 may be a table in which an ETC control cycle having a minimum rotational error rate with respect to the engine rotational speed is set.

As described above, the ETC control period having the minimum rotational speed error rate may have a different value for each engine rotational speed.

As shown in FIG. 3, for example, the ETC control period of 500 ms when the number of revolutions of the engine is 1000 RPM may be the ETC control period of the minimum number of revolutions (8.87).

The ETC control period, which indicates the minimum rotational speed error rate (12.05) when the engine speed is 1200 RPM, can be 700 ms, and the ETC control period can be 700 ms, which indicates the minimum rotational speed error rate (15.75) when the engine speed is 1400 RPM The period can be 800 ms.

The ETC control period, which indicates the minimum rotational error rate (10.11 / 11.75) when the engine speed is 1600 rpm and 1800 rpm, respectively, may be 1000 ms each.

At this time, as shown in FIG. 3, the ETC control period can be adjusted in units of 100 ms.

4 is a flowchart showing an engine control method of an engine power generation system according to an embodiment of the present invention.

First, a step S10 of performing engine speed follow-up control for operating the engine with the target engine speed may be performed.

The engine may not always be driven at the same engine speed, and a situation may occur in which the engine can not be driven at the target engine speed due to a change in the load of the generator or the like. In order to prevent such a situation, control for operating the engine speed at the target engine speed may be performed, which is referred to as engine speed follow-up control.

Thereafter, the engine is operated according to the electronic throttle control (ETC) control cycle on the table set for the number of engine revolutions for the engine (S20).

At this time, as described above with reference to FIG. 3, the table set for the engine may be a table set for the fixed load. Such a table may be a table in which an ETC control period having a minimum rotational speed error rate with respect to the engine rotational speed is set.

That is, the step S20 of operating the engine according to the ETC control period on the table may be the step of applying the ETC control period set for the corresponding engine speed in the above-described table.

In this process, the ETC control period on the table described with reference to FIG. 3 can be applied.

Next, a process of determining the fluctuation range of the engine speed (RPM) may be performed (S30). The determination of the fluctuation range of the engine speed may be periodically performed. For example, such a determination can be made every second.

At this time, the fluctuation range of the engine speed and the manifold absolute pressure (MAP) of the engine can be determined together.

Thereafter, the ETC control period may be adjusted according to this determination (S40, S50, S60). That is, at least one of the fluctuation range of the engine speed and the MAP is determined, and the engine can be controlled by changing the ETC control period.

That is, the step of adjusting the ETC control period includes the steps of (S31), (S32), (S33), and 4 < / RTI > range (S34).

For example, if the fluctuation range of the engine speed is within the first range with respect to the target value (S32), the ETC control period may be delayed by a first time (S40).

If the range of the fluctuation width is the second range larger than the first range (S33), the ETC control period can be delayed by a second time smaller than the first time (S50).

In some cases, the process of delaying the ETC control period may be performed in one step. That is, when the range of the fluctuation width is substantially in the first range to the second range, it is possible to delay the first time.

When the fluctuation range is the third range larger than the second range (S31), the engine can be operated according to the ETC control cycle on the table. That is, in this case, the control may return to the engine speed monitoring (S10) and the ETC control period on the table may be applied (S20).

On the other hand, if the range of the fluctuation width is the fourth range larger than the third range (S34), the ETC control period can be shortened (S60).

Thereafter, the process of controlling the ETC according to the ETC control period set in the above process (S70) may be performed.

Here, the ETC control period can be adjusted between 700 ms and 1200 ms.

5 is a graph illustrating a process of varying the ETC control period according to the engine speed according to an embodiment of the present invention.

For example, in the fluctuation range of the engine speed, the first range is within ± 15 RPM, the second range is within ± 15 RPM and ± 30 RPM, the third range is within ± 30 RPM and ± 50 RPM, The range can be more than ± 50 RPM.

That is, if the fluctuation range of the specific engine speed is set to be within ± 15 RPM of the target range of the first range (S32), the ETC control period can be delayed by 200 ms (delay 1) (S40) The ETC control period may be delayed by 100 ms (delay 2) (S50) if the target value is within the second range of ± 15 RPM or more and within ± 30 RPM (S33).

Here, the first range of ± 15 RPM means that the engine is stabilized with respect to the load. That is, since the engine speed can always be varied within the range of ± 15 RPM according to the control state of the ETC, the mixer density, the distribution of the pressure in the cylinder, etc., this state can be regarded as a state where the engine is stabilized with respect to the load.

The second range of more than ± 15 RPM and ± 30 RPM means that the engine speed is entering the stabilized state slightly off the stabilized state. If the engine is operating in the range of more than ± 15 RPM and ± 30 RPM, it is possible to enter the above stabilization control according to the driving situation and state, It means that the control period is delayed less than the first range state.

A third range of. + -. 30 RPM or greater and. + -. 50 RPM or less may mean a condition in which a general operating state to which the above table may be applied is possible.

On the other hand, the meaning of the fourth range of ± 50 RPM may mean a state for rapidly following the target revolution speed by increasing the control period to quickly follow the target revolution speed. That is, in the low engine speed region, there is no abrupt engine speed fluctuation due to a sufficient margin against the output of the engine. However, since the margin of the engine power is insufficient in the high engine speed region, It may mean a state for rapidly following the target revolution speed by increasing the control period to quickly follow the target revolution speed.

As described above, when the fluctuation range of the engine speed is in the first range, the ETC control period can be adjusted by determining that the fluctuation width of the intake air pressure MAP is within 5 hPa.

That is, if the engine speed error width is within 15 RPM (the first range) and / or the MAP fluctuation width is within 5 hPa, the ETC control period is delayed by 200 ms on the premise that the engine speed is close to the target speed ) It is possible to delay the rise and fall of the engine speed.

On the other hand, if the fluctuation range is ± 30 RPM or more and ± 50 RPM or less (S31) with respect to the target value in the third range, the ETC control period on the table can be applied (normal control) (S20) If it is more than ± 50 RPM (S34), the ETC control period can be shortened from 1000 ms to 700 ms (S60).

If the fluctuation range of the engine speed is within the range of ± 30 RPM (S33), it is determined that the range of the engine speed is within the stable range of the control period, so that the control can be delayed by about 100 ms (S50).

However, if the fluctuation range of the engine speed is equal to or more than 50 RPM with respect to the target value (S34), it is determined that the engine is severely hunting, so that the ETC control period is shortened to 700 ms so as to rapidly follow the target (S60).

On the other hand, if the fluctuation range of the engine speed is ± 30 RPM or more and ± 50 RPM or less (third range) with respect to the target value, step S31 can be controlled based on the ETC control cycle table.

6 is a graph schematically showing the engine speed at the time of operation when the variable ETC control period according to the embodiment of the present invention is applied.

Comparing FIG. 6 with FIG. 2, it can be seen that the extent to which the engine speed deviates from the target speed is relatively small, and therefore the target compliance of the engine speed can be greatly improved.

7 is a graph showing an engine speed error rate according to a load variation when the embodiment of the present invention is applied.

Referring to FIG. 7, the error ratios of the engine speed (RPM) when the RL load is changed to 10 kW, 20 kW, and 30 kW, respectively, in the rotational speed range of 1000 RPM to 1800 RPM are shown.

8, 9, and 10 show graphs showing the target rotational speed tracking performance in the case where the loads are 10 kW, 20 kW, and 30 kW, respectively. 8, 9, and 10 are graphs showing the engine speed tracking performance when the engine target engine speed is increased stepwise by 200 RPM.

At this time, the ETC control period was controlled according to the method described above, and the error rate with respect to the engine speed was examined.

As a result of the examination, in FIG. 7 and FIG. 8, when a load of 10 kW is applied, an error rate of up to 3.35% and an engine speed error rate of at least 1.1% can be confirmed in both 1000 to 1800 RPM regions.

7, 9 and 10, it can be confirmed that the engine speed error rate does not exceed a maximum of 5% or more even in the case of 20 kW and 30 kW. That is, it can be seen that the best condition is shown in most of the regions.

As described above, it can be seen that, when the present invention is applied, the stability of the engine due to the change in the engine speed and the load change can be optimized.

Referring to FIG. 7, it can be seen that the region of 1000 RPM in the case of 20 kW load and 1000-1200 RPM in case of 30 kW load are not stabilized, but this is a problem area.

That is, since the power generation amount is controlled based on 10 kW in the case of the load 10 kW, the actual engine control region operates in the range of 1300 to 1500 RPM, in the range of 1500 to 1600 RPM in the case of 20 kW, and in the range of 1700 to 1800 Since the operation is performed only in the RPM region, it can be confirmed that there is no problem in the operation region of the low engine speed region with high load.

As described above, according to the present invention, the target engine speed follow-up performance can be greatly improved in the engine speed stabilizing region based on the variable control period of the ETC, and when the engine power generation control is performed based on this, It is possible to achieve stable development.

As described above, in the case of the cogeneration system to which the present invention can be applied, the temperature of the engine cooling water is extremely lowered when the thermal efficiency is controlled to the maximum, so that the load of the engine is slightly increased in operation, So that the mechanical friction is increased.

Therefore, even when the engine is operated in a steady manner due to the increase of the mechanical friction due to the increase in the mechanical friction, the hunting of the smile occurs. However, when the present invention is applied, the engine can be operated more stably can confirm.

11 is a block diagram briefly showing an essential part of an engine power generation system in which the present invention can be implemented.

Referring to FIGS. 1 and 11 together, the control unit 110, which performs the control process described above, controls the operation of the engine 30 including the engine 30 and various sensors and valves.

The engine 30 is provided with an engine speed sensor 33 to calculate the RPM of the engine 30 per minute.

In addition, a MAP sensor (Manifold Absolute Pressure Sensor) 35 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) 38 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.

At this time, the controller 110 controls the operation of the engine 30 by adjusting the opening of the fuel valve 13 and the opening of the ETC valve 38. As the opening degree of the fuel valve 13 and the opening degree of the ETC valve 38 become larger, the engine speed can be increased.

The controller 110 may be included in the power converter 90, but may be separately provided in the other portions.

That is, the control unit 110 performs the engine speed follow-up control for operating the engine at the target engine speed and, in accordance with the electronic throttle control (ETC) control cycle on the table set for the engine 30 when no- The engine 30 can be operated to determine the fluctuation range of the engine speed, adjust the ETC control period according to the range of the fluctuation width, and operate the engine 30 according to the varied ETC control period.

At this time, the controller 110 may adjust the ETC control period from 700 ms to 1200 ms. In addition, the process of determining the fluctuation range of the engine speed can be repeatedly performed at predetermined time intervals. In this manner, the engine 30 can be operated by determining the fluctuation range and applying the ETC control period variably by the process as described above.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

30: engine 40: generator
90: power converter 100: cogeneration system
110:

Claims (13)

A method of controlling an engine for driving a generator,
Performing engine speed follow-up control for operating the engine with the target engine speed;
Operating the engine according to an electronic throttle control (ETC) control cycle on the table set for each engine revolution number for the engine in a fixed load;
Determining a fluctuation range of the engine speed;
Delaying or shortening the ETC control period according to the range of the variation width; And
And operating the engine according to the changed ETC control period,
Wherein the adjusting the ETC control period comprises:
Delaying the ETC control period by a first time when the variation range is in a first range; And delaying the ETC control period by a second time shorter than the first time when the range of the variation width is in a second range larger than the first range . 2. The method of claim 1, wherein the adjusting the ETC control period comprises:
Determining an optimal position on a table for a current state of the engine and applying an ETC control cycle on the table. delete The engine control method according to claim 1, wherein the determination of the manifold absolute pressure (MAP) of the engine together with the fluctuation of the engine speed is made. 5. The engine power generation system according to claim 4, wherein when the range of the fluctuation width is in the first range, the ETC control period is delayed by the first time only when the variation width of the intake air pressure is within 5 hPa Control method. The engine control method of an engine power generation system according to claim 1, wherein the engine is operated in accordance with an ETC control cycle on the table when the range of the variation width is in a third range larger than the second range. 7. The method according to claim 6, further comprising the step of shortening the ETC control period when the range of the fluctuation width is in a fourth range larger than the third range. 2. The method according to claim 1, wherein the ETC control period is adjusted between 700 ms and 1200 ms. 9. The method according to claim 8, wherein the ETC control period is adjusted in units of 100 ms. The engine control method according to claim 1, wherein the step of determining the fluctuation range of the engine speed is repeatedly performed at predetermined time intervals. In an engine power generation system,
generator;
An engine connected to a drive shaft of the generator to drive the generator; And
And a control unit for controlling the engine,
Wherein the control unit performs engine speed follow-up control for operating the engine at a target engine speed and operates the engine in accordance with an electronic throttle control (ETC) control cycle on a table set for the engine when no load is applied, Determining a fluctuation range of the number of revolutions, adjusting the ETC control period by delay or shortening according to the range of the fluctuation width, operating the engine according to the changed ETC control period,
Wherein the control unit delays the ETC control period by a first time when the range of the fluctuation width is in the first range and sets the ETC control period to the first range when the range of the fluctuation width is in a second range larger than the first range, ≪ / RTI > wherein the first time delay is less than the second time. 12. The engine power generation system according to claim 11, wherein the ETC control period is adjusted between 700 ms and 1200 ms. 12. The apparatus according to claim 11,
Wherein the step of determining the variation range of the engine speed is repeatedly performed at predetermined time intervals.

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