KR101025772B1 - The control method for staring the gas turbine engine - Google Patents

Abstract

According to the present invention, when the gas turbine engine is controlled by the electric motor and the fuel injection amount during starting, the gas turbine engine is driven by stepping the electric motor so that the output by the electric motor and the output by fuel injection always drive the rotating shaft in the same direction. An object of the present invention is to provide a start control method of the gas turbine engine. (A) increasing the revolutions per minute (RPM) of the rotating shaft to a first RPM by driving the electric motor; and (b) driving the electric motor step by step and simultaneously driving the electric motor. Injecting fuel into the combustor of the gas turbine engine to drive the gas turbine engine, thereby increasing the RPM of the rotary shaft to the second RPM And (c) interrupting the drive by the electric motor and increasing the RPM of the rotary shaft only by driving the gas turbine engine by the fuel injection. Provide a method.

Description

The control method for staring the gas turbine engine}

1 is a schematic configuration diagram of a general gas turbine engine,

FIG. 2 is a temperature-entropy diagram showing the state points at each position of the gas turbine engine of FIG. 1,

3 is a flowchart showing a start control step of a gas turbine engine according to an embodiment of the present invention;

4 is a graph illustrating a change in relative RPM of a rotating shaft by the start control method of the gas turbine engine of FIG. 3.

Explanation of symbols on the main parts of the drawings

10 compressor 20 turbine

30: electric motor 40: combustor

50: rotation axis 60: fuel amount control means

70: control unit 80: rotation speed detection unit

100: gas turbine engine

The present invention relates to a start control method for a gas turbine engine, and more particularly, to a start control method for a gas turbine engine started using an electric motor.

Typically, a gas turbine engine is a device operated by the Brayton Cycle, which is an ideal basic thermodynamic cycle, which continuously obtains power in the process of compressing and expanding a gaseous working fluid. These gas turbine engines consume very little lubricating oil, and because they can operate at high speeds, they can be miniaturized and concentrated. have.

By the way, a gas turbine engine is largely equipped with a compressor, a combustor, and a turbine. Since gas turbine engines are characterized by the shaft work generated at the turbine at a lower speed than the shaft work required at the compressor, a separate electric motor must be installed when driven at a low speed such as starting.

The start control method of a general gas turbine engine is largely divided into three stages. In the first stage, electric power is applied to the electric motor which is engaged with the rotary shaft of the gas turbine engine, thereby increasing the RPM of the rotary shaft. If the rotation speed increases to the target value, control of the second stage is started. In the second stage, fuel is injected into the combustor of the gas turbine engine, and the fuel injection generates its own output. However, the drive of the electric motor continues. When the PRM reaches a different target value by simultaneous operation of the electric motor and the gas turbine engine, the third stage begins, where the power applied to the electric motor is cut off and the amount of fuel injected into the combustor of the gas turbine engine is increased. The RPM of the rotating shaft is increased to another target value.

In the second step, the electric motor is controlled such that the RPM of the rotating shaft has a constant rate of increase. In addition, the fuel injected into the gas turbine engine is controlled such that the RPM of the rotating shaft has a constant increase rate, or the flow rate is injected according to a preset schedule.

By the way, when the fuel injection amount is controlled such that the RPM of the rotating shaft has a constant increase rate, there is a possibility that the electric motor and the fuel control are set to have different increase rates. In this case, there is a problem that, among the electric motor and the gas turbine engine driving the rotating shaft, one set such that the RPM increase rate is low acts as the other resistance.

In addition, even when fuel is injected into the gas turbine engine according to a predetermined schedule, a problem occurs when the fuel flow rate is excessively injected into the gas turbine engine. That is, since the electric motor is controlled to have a constant speed increase rate, in order to suppress excessive output generated in the gas turbine engine, the electric motor must generate an output having a driving force in the opposite direction. Therefore, a problem of unnecessary power consumption occurs.

In order to solve the above problems, the present invention, when controlling the gas turbine engine by the electric motor and the fuel injection amount at the start, by step-controlling the electric motor, the output by the electric motor and the output by the fuel injection is always the same An object of the present invention is to provide a start control method for a gas turbine engine that drives a rotating shaft in a direction.

In order to achieve the above objects and other objects, the present invention provides a gas turbine engine start control method for starting the gas turbine engine by using an electric motor coupled to the rotary shaft of the gas turbine engine, (a) By driving the electric motor, increasing the revolutions per minute (RPM) of the rotary shaft to a first RPM, (b) step-drive the electric motor to drive, and at the same time to the combustor of the gas turbine engine Injecting fuel to drive the gas turbine engine, thereby increasing the RPM of the rotary shaft to a second RPM, and (c) interrupting the drive by the electric motor and driving the gas turbine engine by the fuel injection. It provides a start control method for a gas turbine engine, characterized in that it comprises the step of increasing the RPM of the rotary shaft only.

In the step (a), it is preferable to control the electric motor so that the RPM of the rotating shaft has a preset increase rate.

In the step (b), it is preferable that the magnitude of the current applied to the electric motor is kept below a predetermined value.

In addition, in the step (b), it is preferable to control the fuel injection amount so that the RPM of the rotating shaft reaches the second RPM within a predetermined time.

In addition, in the step (c), it is preferable to control the fuel injection amount so that the RPM of the rotating shaft has a preset increase rate.                     

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

1 is a schematic configuration diagram of a general gas turbine engine, and FIG. 2 is a temperature-entropy diagram showing a state point at each position of the gas turbine engine of FIG. 1.

Referring to FIG. 1, a gas turbine engine 100 includes a compressor 10 for compressing air, a combustor 40 for mixing compressed air with fuel, and a turbine 20 for expanding combustion gas after combustion. Equipped.

The compressor 10 performs a function of compressing air in a state of a first point flowing from an inlet duct (not shown). The compression raises the temperature and pressure of the air. If the isotropic efficiency of the compressor 10 is 1, the state of air at the compressor outlet is the second s point. However, due to heat loss, irreversibility, etc. in the compressor 10, the compressed air is in a state of the second point where the entropy is increased from the second point. Compressors are classified into reciprocating, rotary, centrifugal, and the like according to the compression method.

The air, which has become high pressure by the compressor 10, is mixed with fuel in the combustor 40 and combusted. The combustion gas generated by the combustion becomes a state of high temperature and high pressure having a state of the third point. The combustion process in the combustor 40 is generally assumed to be an isostatic process.

Combustion gas discharged from the combustor flows into the turbine 20. If the efficiency of the turbine 120 is 1, it flows out in the state of point 4s, but becomes the state of the fourth point due to irreversibility of the turbine, heat transfer, and the like. At this time, part of the output generated from the turbine is used to drive the compressor.                     

As shown in FIG. 1, the turbine 20 and the compressor 10 are connected by a coaxial 50. Turbine 20 and the compressor 10 as a rotary device for a rotary motion, each may have an independent axis of rotation, but to simplify the structure and to transmit the output from the turbine 20 to the compressor 10 as it is, It is connected to each other coaxial 180.

In addition, the electric motor 30 is provided on the rotation shaft 50 connecting the turbine 120 and the compressor 110. The electric motor 30 is arranged for starting the gas turbine engine 100. In particular, the electric motor 30 is used in the initial stage of starting of the gas turbine engine 100.

The gas turbine engine 100 includes a controller 70 for driving control. The controller 70 receives input signals such as temperature, pressure, and output from various points, and outputs driving signals to the various drives. 1 shows a flow of control signals used in a control method of a gas turbine engine according to an embodiment of the present invention with a dotted line. As shown in the drawing, the controller 70 receives an RPM signal of the rotation shaft 50 from the revolutions per minute (RPM) sensor 80, and drives signals to the fuel amount control means 60 and the electric motor 30. Outputs The fuel amount control means 60 and the electric motor 30 control the fuel injection amount and the output of the electric motor, respectively, in accordance with the drive signal.

3 is a flowchart illustrating a start control step of the gas turbine engine 100 according to an exemplary embodiment of the present invention. 4 is a graph showing a relative RPM of a rotating shaft with time of a gas turbine engine controlled by the start control method of FIG. 3. Where the horizontal axis is time and the vertical axis is relative RPM, expressed as a percentage, of the ratio of RPM to rated RPM.

The start control method of the gas turbine engine 100 includes driving the electric motor 30 to increase revolutions per minute (RPM) of the rotation shaft 50 to the first RPM, and stepping the electric motor 30. Driving the gas turbine engine 100 by injecting fuel into the combustor 40 of the gas turbine engine 100 while controlling and driving the motor, thereby increasing the RPM of the rotating shaft 50 to a second RPM; and Blocking the drive by the motor 30, and increasing the RPM of the rotary shaft 50 only by driving the gas turbine engine 100 by the fuel injection. Hereinafter, the above steps will be described in detail.

The controller 70 drives the gas turbine engine 100 in the stopped state using the electric motor 30 (step S10). The electric motor 30 may be controlled in various ways, but it is preferable to control the RPM increase rate of the rotation shaft 50 to be constant.

At this time, the controller 70 causes the fuel amount control means 60 not to inject fuel into the combustor 60 of the gas turbine engine 100. Thus, the RPM change of the rotational shaft depends entirely on the output of the electric motor 30. If the increase rate of the RPM is to be increased, the output of the electric motor 30 is kept large, and if the increase rate of the RPM is to be reduced, the output of the electric motor 30 is kept small. In this embodiment, the electric motor 30 is controlled such that the RPM of the rotation shaft 50 has a preset increase rate. Thus, the RPM has a constant increase in value up to about 15 seconds. By the driving of the electric motor 30, the RPM of the rotating shaft 50 is accelerated until it reaches 17% of the rated rotation speed which is the first RPM (step S20).                     

Between about 15 and 17 seconds after starting, the electric motor 30 is controlled so that the RPM of the rotating shaft 50 is kept constant. This time period is an ignition waiting time of the combustor 40 and can be omitted according to the start schedule of the gas turbine engine 100.

Thereafter, a step control signal is input to the electric motor 30 (step S31). Here, the step control is to change the output of the electric motor 30 using the difference between the target RPM and the current RPM as an input variable. Therefore, when the difference is large, the output size is controlled to be large, and when the difference is small, the output is reduced. However, since the difference between the target rotational speed and the current rotational speed is large at first, there is a risk that an excessively large current flows into the electric motor. Therefore, a current limit (not shown) is provided to control the magnitude of the current flowing into the electric motor 30 to be maintained below a predetermined value. However, in order to shorten the starting time, it is preferable that the output of the electric motor 30 is maintained close to the maximum output.

At the same time as driving the electric motor 30, the control unit 70 causes the fuel amount control means 60 to inject fuel into the combustor 40 (step S32). Therefore, the fuel introduced into the combustor 40 is mixed with the air introduced into the compressor 10 and combusted. The combustion gas drives the turbine 20 to generate the output of the gas turbine engine 10 itself. Here, the net power of the gas turbine engine is a value obtained by subtracting the required output of the compressor 10 from the output generated from the turbine 20. However, since the output of the electric motor 30 is relatively large, the net output of the gas turbine engine 100 performs an auxiliary function of the output of the electric motor 30.                     

The RPM increase rate of the rotation shaft 50 is determined by the sum of the output of the electric motor 30 and the net output of the gas turbine engine 100. In this embodiment, the amount of fuel injected into the combustor 40 is not feedback controlled, and fuel is injected according to a preset fuel amount schedule. At this time, it is preferable to set the fuel injection schedule to reach the second RPM within a predetermined time.

RPM of the rotating shaft 50 is increased by the output of the electric motor 30 and the net output of the gas turbine engine 100, and until the RPM of the rotating shaft 50 reaches 50% of the rated rotation speed of the second RPM. Accelerated (step S40).

When the RPM of the rotating shaft 50 reaches the second RPM, the output of the electric motor 30 driving the rotating shaft 50 is removed (step S51). However, fuel injection to the combustor 40 is continued (step S52).

Although the output of the electric motor 30 is thus removed, the RPM of the rotating shaft 50 is accelerated. This is because the amount of fuel flowing into the combustor 40 and the amount of air flowing from the compressor 10 are increased in the state where the RPM is relatively high, and the net output of the gas turbine engine 100 is increased as a whole. Therefore, even if there is no output of the electric motor 30, it is possible to increase the RPM of the rotary shaft 50 due to the output of the gas turbine engine 100 itself. In this case, the amount of fuel injected into the gas turbine engine 100 may be controlled in various ways, but preferably, the RPM increase rate of the rotation shaft 50 is controlled to be constant. When the RPM of the rotary shaft reaches the rated rotation speed, the start schedule of the gas turbine engine 100 is terminated (step S60).                     

Like reference numerals in the drawings shown above indicate the same members.

The start control method of the gas turbine engine according to the present invention has the following effects.

First, when the rotary shaft of the gas turbine engine is accelerated by the electric motor and fuel injection, the electric motor is step controlled, so that the output of the gas turbine engine by fuel injection is added to the output of the electric motor. Therefore, the driving force by the electric motor and the output by fuel injection always drive the rotating shaft in the same direction.

Second, when the rotation shaft of the gas turbine engine is accelerated by the electric motor and fuel injection, when the output of the electric motor is kept close to the maximum output, the RPM increase rate of the rotation shaft is maximized, and the starting time is reduced.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (5)

In the start control method of a gas turbine engine for starting the gas turbine engine by using an electric motor coupled to a rotary shaft of a gas turbine engine, (a) increasing the revolutions per minute (RPM) of the rotary shaft to a first RPM by driving the electric motor; (b) increasing the RPM of the rotation shaft to a second RPM by driving the electric motor by controlling the electric motor step by step and injecting fuel into a combustor of the gas turbine engine to drive the gas turbine engine; (c) blocking driving by the electric motor and increasing the RPM of the rotating shaft only by driving the gas turbine engine by the fuel injection; and controlling the start of the gas turbine engine. The method of claim 1, wherein in step (a), Starting control method for a gas turbine engine, characterized in that for controlling the electric motor so that the RPM of the rotating shaft has a predetermined increase rate. The method of claim 1, wherein in step (b), And a magnitude of a current applied to the electric motor is kept below a predetermined value. The method of claim 1, wherein in step (b), And controlling the fuel injection amount such that the RPM of the rotary shaft reaches the second RPM within a predetermined time. The method of claim 1, wherein in step (c), Starting control method of a gas turbine engine, characterized in that for controlling the fuel injection amount so that the RPM of the rotating shaft has a predetermined increase rate.

Images