JPH076413B2 - Gas turbine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of use) The present invention relates to a gas turbine control device, and more particularly to feeding back a detected value of an actual fuel flow rate to a gas turbine combustor, The present invention relates to a gas turbine controller that controls an actual fuel flow rate by integrating a difference with a set fuel flow rate with an integration element.

(Prior Art) Generally, in a gas turbine plant, a compressor that compresses air taken in from the atmosphere, a combustor that combusts fuel mixed with compressed air from the compressor, and a combustion that occurs in the combustor. A gas turbine that is rotationally driven by gas and a generator that generates electric power by the rotational force transmitted from the gas turbine are provided.

The gas turbine control device for controlling the gas turbine plant configured as described above is an integrated control of each component, but the gas turbine plant is a difficult control target in terms of control technology.

For example, the temperature of the combustion gas flowing into the gas turbine is very close to the service limit temperature that the turbine blade metal can tolerate, so the temperature rise of the combustion gas is limited to a certain value, and the temperature is accurately controlled. Need to be restricted. Further, it is necessary to strictly control the rotation speed even during acceleration or load operation. Further, during the ignition operation, it is necessary to control the fuel amount so that the ratio of the amount of air flowing into the combustor and the amount of fuel to be injected (air-fuel ratio) becomes an optimum value.

In the gas turbine control device, in order to satisfy various requirements on the gas turbine plant side, a plurality of control systems are provided as a lower limit control system, while a functional separation for each control system is provided. A selection circuit is provided, and the fuel supply flow rate to the combustor is controlled by these control system and selection circuit.

Further, a gas turbine plant and a gas turbine control device incorporated in the gas turbine plant will be described with reference to the drawings.

FIG. 3 is a block diagram of a general gas turbine plant.

A compressor 1 is provided in the gas turbine plant, and the air that has flowed into the compressor 1 from the atmosphere is sent to the combustor 2 after being compressed by the compressor 1. The compressed air sent to the combustor 2 is mixed with fuel to form an air-fuel mixture, and the air-fuel mixture is combusted to form high-temperature combustion gas. This combustion gas is sent to the gas turbine 3 and rotationally drives the gas turbine 3, and the rotational force is transmitted to the generator 5 via the turbine shaft 4 to generate electric power.

Further, the rotational force of the turbine shaft 4 is transmitted to the fuel pump 7 via the gear device 6, and the fuel pump 7 is driven to supply the liquid fuel to the combustor 2. . And the control of this fuel supply flow rate is
This is performed by adjusting the opening of the feedback control valve 9 according to the feedback valve opening command a from the gas turbine control device 8 and returning a part of the fuel on the discharge side of the fuel pump 7 to the inlet side of the fuel pump 7. The controlled fuel supply flow rate is detected by the fuel flow rate detector 10, and the fuel flow rate detection signal b is fed back to the gas turbine control device 8.

FIG. 4 is a configuration diagram showing a gas turbine control device 8 incorporated in the gas turbine plant.

The gas turbine control device 8 includes various command control systems 13, a low value priority circuit 14, a subtractor 15, an integration element 16, an adder 17, and a proportional element.
Composed of 18.

The command control system 13 as the lower limit control system includes a load / speed control system 20 for outputting a load / speed control signal c so as to obtain a target generator output and rotation speed, and a gas of combustion gas. A combustion gas temperature control system 21 that outputs a combustion gas temperature limit signal d that keeps the turbine inlet temperature below a set value, and a start control signal e that accelerates the rotation speed to a rated rotation speed after ignition.
A start-up control system 22 for outputting the ignition control system 22 and an ignition control system 23 for outputting a fuel setting signal f during ignition so as to supply a fuel suitable for ignition during ignition.

Each of the signals c, d, e, f is output according to the operating state of the gas turbine due to the characteristics of each command control system 20, 21, 22, 23, and is input to the low value priority circuit 14 as a selection circuit. It The low value priority circuit 14 selects the minimum value of the plurality of signals and outputs the minimum value signal as the fuel flow rate command signal g.

The fuel flow rate command signal g is subtracted by the subtractor 15 from the fuel flow rate detection signal b fed back from the fuel flow rate detector 10, and the deviation thereof is output as a deviation signal h. The deviation signal h is input to the integration element 16 and the adder 17, and the integration element 16 integrates the deviation signal h under a preset integration time constant and then outputs it as an integration element output i.
This integral element output i is added to the deviation signal h by the adder 17, and then the addition signal j is multiplied by a preset proportional constant in the proportional element 18, and then the proportional element 18 outputs the feedback control valve 9 The feedback valve opening command a is output to.

(Problems to be Solved by the Invention) However, when attention is paid to the ignition control system 23 in the above control circuit, the following problems occur.

That is, the ignition-time fuel setting signal f output from the ignition control system 23 performs the fuel flow rate command in a step function, while the proportional element including the integral element 16 and the proportional element 18 is used.
Feedback valve opening command a output from the integral control system
Does not change stepwise from control theory. For example, if the proportional constant and integral time constant are adjusted so that an equivalent output is obtained on the output side when the input of the proportional / integral control system increases stepwise, that is, there is no delay in the output with respect to the input. In such a case, a phenomenon occurs in which the feedback valve opening command a as an output indicates an overshoot operation.

The above will be further described with reference to the drawings.

FIG. 5 is a diagram showing changes in the set fuel flow rate, the actual fuel flow rate, and the actual rotational speed on the time axis.

In FIG. 5, at the point A on the time axis, the rotation speed is the value x
Even if the fuel flow rate command signal g having the value y is output when the ignition speed reaches, the feedback valve opening command a does not change stepwise. Since the fuel is liquid fuel, the fuel flow rate is uniquely determined with respect to the opening degree of the feedback control valve 9, and the actual fuel flow rate gradually increases as B → C → D.

Also, after ignition, reduce the air-fuel ratio to near the blow-off limit (the limit at which misfiring will occur if throttled further), and the turbine casing,
When the fuel flow rate command signal g having the value z is output at the time axis E point in order to perform warm-up operation of the turbine dynamic vanes, the trajectory of the actual fuel amount is as D → G → H up to the point F on the time axis. It descends gently.

The actual fuel flow rate gradually increases or decreases in this way, and the actual fuel flow rate overshoots (value y
Upper part) and undershoot (lower part than the value z) operation is shown.

These overshoot and undershoot operations are
The following problems occur on the main unit side.

That is, the ignition operation has an ignition point determined by the ratio of air and fuel, and the ignition operation at an air-fuel ratio other than this ignition point causes ignition failure. In addition, the undershoot operation after ignition may narrow down to below the blowout limit, causing a misfire.

In order to prevent the above ignition failure, the ignition request fuel amount is reached. Even if the ignition start operation is performed at the point I, which is Δt seconds before the point A, in consideration of the interval Δt, the overshoot and undershoot operations cannot be solved, and the actual fuel flow rate during the ignition operation is not solved. It is not possible to solve the problem of poor followability with respect to the set fuel flow rate.

The present invention has been made in consideration of the above circumstances, and improves the followability of the actual fuel flow rate with respect to the change in the set fuel flow rate during and after ignition, and prevents ignition failure and misfire after ignition to prevent gas turbines. An object of the present invention is to provide a gas turbine control device capable of stably operating a plant.

[Structure of Invention]

(Means for Solving the Problems) The present invention feeds back the detected value of the actual fuel flow rate to the gas turbine combustor and integrates the difference between the detected value and the set fuel flow rate by an integral element to obtain the actual fuel flow rate. In the gas turbine control device to control, the value of the output of the integral element is forcibly set to obtain the set fuel flow rate at the time of ignition and after ignition, and the value of the output of the integral element after reaching the set fuel flow rate. Is provided with an integral element output control device for limiting.

(Operation) First, at the time of ignition, the integral element output controller forcibly sets the integral element output to obtain the set fuel flow rate at ignition. After the actual fuel flow rate reaches the ignition set fuel flow rate, the integral element output control device limits the integral element output, and the actual fuel flow rate is limited to the ignition set fuel flow rate or less.

After that, the ignition operation is performed, and after the ignition is confirmed, the integral element output control unit forcibly sets the integral element output to obtain the set fuel flow rate after ignition.

After the actual fuel flow rate reaches the set fuel flow rate after ignition, the integral element output control device limits the integral element output, and the actual fuel flow rate is limited to the post-ignition set fuel flow rate or more.

In this way, since the actual fuel flow rate is made to follow the set fuel flow rate by the integral element output control device, overshoot and undershoot operations do not occur in the actual fuel flow rate, and ignition failure and misfire after ignition are prevented. .

(Embodiment) An embodiment of a gas turbine control device according to the present invention will be described with reference to the drawings.

The same parts as those of the conventional gas turbine control device 8 are designated by the same reference numerals and the description thereof will be omitted.

The gas turbine control device 29 is provided with an integral element output control device 30 for controlling the integral element output i as shown in FIG. 1, and the integral element output control device 30 has a post-ignition control system 31,
Cantilevered elements 32,33 and subtractors 34,35 are provided. The ignition control system 31 includes an ignition flow rate setter 36, a post-ignition flow rate setter 37, switching devices 38 to 42, an oversaturation prevention setting device 43, an oversubtraction prevention setting device 44, and subtractors 45, 46. To be

The ignition flow rate setting unit 36 outputs an ignition flow rate setting signal 1 when performing ignition, and the post-ignition flow rate setting unit 37 outputs a post-ignition flow rate setting signal m after confirmation of ignition.

In addition, the switching devices 38 to 42 are connected to each contact in a preset order.
It is designed to switch between 50 and 64.

That is, before the gas turbine is started, the switch 38 has the contacts 50 and 51, the switch 39 has the contacts 53 and 54, the switch 40 has the contacts 57 and 58, the switch 41 has the contacts 60 and 61, and the switch 61. 42
The contact 62 and the contact 63 are in a conductive state.

Then, first, when the number of revolutions of the gas turbine reaches a predetermined number of revolutions, the switching device 40 operates to bring the contacts 57 and 56 into conduction, and the ignition flow rate setting signal output from the ignition flow rate setter 36. l flows through each contact 50, 51, 53, 54, 56, 57 and is input to the subtractor 45.

Next, when the actual fuel flow rate reaches the set flow rate at ignition, the switching device 38 operates and the contact 50 and the contact 52 become conductive,
The ignition flow rate setting signal 1 output from the ignition flow rate setter 36 flows through the contacts 50, 52, 61, 60, 62, 63 and is input to the subtractor 46.

After that, when ignition is confirmed, the switch 41 operates to bring the contacts 59 and 60 into a conductive state, and the post-ignition flow rate setting signal m output from the post-ignition flow rate setter 37 outputs the contact points 59, 6 respectively.
It flows through 0, 62, 63 and is input to the subtractor 46.

Furthermore, when the actual fuel flow rate reaches the set flow rate after ignition,
The switching device 39 and the switching device 42 operate, and the contact 54 and the contact 55,
The contact 63 and the contact 64 are respectively in a conductive state, and the post-ignition flow rate setting signal m output from the post-ignition flow rate setting device 37 is each contact point.
It flows through 55, 54, 56, 57 and is input to the subtractor 45.

The subtractor 45 receives the ignition flow rate setting signal 1 or the post-ignition flow rate setting signal m, performs subtraction with the integral element output i, and outputs a deviation signal n after subtraction to the cantilever element 32. To do. Similarly, the subtractor 46 also inputs the flow rate setting signal 1 at ignition or the flow rate setting signal m after ignition, performs subtraction with the integral element output i, and then outputs the deviation signal o after subtraction to the cantilever element. It is designed to output to 33.

The cantilever element 32 outputs an output equivalent to the input with a linear function only when the input deviation signal n has a negative value. Further, the cantilever element 33 is adapted to perform the same output as the input with the temporary function only when the input deviation signal o has a positive value.

The subtractor 34 subtracts the deviation signal n from the cantilever element 32 and the deviation signal h input from the subtractor 15 through the subtractor 35, and integrates the deviation signal p after the subtraction. Output to element 16. Further, the subtractor 35 subtracts the deviation signal o from the cantilever element 33 and the deviation signal h from the subtractor 15, and the deviation signal g after subtraction is sent to the integration element 16 via the subtractor 34. It is designed to output.

Further, the over-subtraction prevention setting device 45 is configured to prevent over-subtraction of the integral element output i when the contact 58 and the contact 57 are in a conductive state.
Oversaturation of the integral element output i is prevented when the 63 and the contact point 64 are in a conductive state.

Next, the operation of the above embodiment will be described with reference to FIG.

First, when the turbine shaft 4 is rotated by a starting electric motor or the like to reach a predetermined rotation speed x, that is, at point A on the time axis, the ignition flow rate setting device 36 outputs the ignition flow rate setting signal l. At the same time, the switching device 40 operates to bring the contacts 57 and 56 into conduction. Then, the ignition flow rate setting signal 1 flows through the contacts 50, 51, 53, 54, 56, 57 and is input to the subtractor 45.

Although the integral element output i is also input to the subtractor 45, in this case, since the value of the integral element output i is 0, the ignition flow rate setting signal l becomes a negative value as it is and the cantilever element 32. After being input, it is input to the subtractor 34, subtracted, and then input to the integration element 16. Therefore, the integral element 16 performs the integral operation until the integral element output i has the same value as the ignition flow rate setting signal l.
In this way, since the integral element output i is forcibly set to the value of the ignition flow rate setting signal l, the actual fuel flow rate rapidly rises and reaches the ignition time set flow rate.

When the actual fuel flow rate reaches the ignition set flow rate, that is, at the point K on the time axis, the switch 38 operates and the contact point 50 and the contact point
52 becomes conductive, and the ignition flow rate setting signal 1 output from the ignition flow rate setter 36 is input to the subtractor 46 through the respective contacts 50, 52, 61, 60, 62, 63. The subtractor 46 subtracts the ignition flow rate setting signal 1 from the integral element output i, and only when the integration element output i becomes larger than the ignition flow rate setting signal l, the deviation signal o becomes a positive signal. Cantilever element 33
And is output to the subtractor 35.

The deviation signal o input to the subtractor 35 is
After being subtracted from the deviation signal h at, it is input to the integration element 16 via the subtractor 34. Therefore, the integral element 16 cannot output the integral element output i exceeding the ignition flow rate setting signal l, and the integral element output i is limited to the ignition flow rate setting signal 1 or less. As a result, the actual fuel flow rate is suppressed below the set flow rate during ignition, and the overshoot operation is prevented.

After that, an ignition operation is performed, and when ignition is confirmed,
That is, at the point L on the time axis, the post-ignition flow rate setter 37
The post-ignition flow rate setting signal m is output from the switch, and the switch 41 operates to bring the contacts 59 and 60 into conduction, so that the post-ignition flow rate setting signal m passes through the respective contacts 59, 60, 62, 63. And is input to the subtractor 46.

In this case, since the integral element output i is larger than the post-ignition flow rate setting signal m, the deviation signal o passes through the cantilever element as a positive signal and is input to the integral element 16 via the subtracters 35 and 34. Therefore, the integral element 16 performs the integral operation until the integral element output i becomes the same value as the flow rate setting signal m after ignition. In this way, since the integral element output i is forcibly set to the value of the ignition flow rate setting signal m, the actual fuel flow rate drops sharply and reaches the set flow rate after ignition.

When the actual fuel flow rate reaches the set flow rate after ignition, that is, at the point M on the time axis, the switching unit 39 and the switching unit 42 operate to bring the contacts 55 and 54, and the contacts 63 and 64 into conduction, respectively. After ignition, the set flow rate signal m flows through the contacts 55, 54, 56, 57 and is input to the subtractor 45. Then, the subtractor 45 subtracts the post-ignition set flow rate signal m from the integral element output i, and only when the integral element output i becomes small, the deviation signal n is input to the subtractor 34 as a negative signal. . The deviated sign n is subtracted by the subtractor 34 and then input to the integration element 16.

Therefore, the integral element 16 cannot output the integral element output i smaller than the post-ignition flow rate setting signal m, and the integral element output i is limited to the post-ignition flow rate setting signal m or more. As a result, the actual fuel flow rate is limited to the set flow rate after ignition and the undershoot operation is prevented.

Then, after ignition, warm-up operation is performed at the set flow rate,
After the warm-up is completed (after the point N), the set fuel flow rate is gradually increased by the start signal e from the start control system 22, and the actual fuel flow rate is also increased accordingly.

In the above embodiment, the integral element output controller 30 controls the integral element output i, so that even if the set fuel flow rate changes stepwise, the actual fuel flow rate can be made to follow stepwise. Become. Therefore, overshoot and undershoot operations do not occur in the actual fuel flow rate, ignition failure and misfire after ignition are prevented, and it becomes possible to operate the gas turbine plant extremely stably.

〔The invention's effect〕

The gas turbine control device according to the present invention forcibly sets the value of the output of the integral element in order to obtain the set fuel flow rate during and after ignition, and after the set fuel flow rate is reached, the value of the output of the integral element Since the integral element output control device for limiting the above is provided, it is possible to make the actual fuel flow rate substantially follow the change in the set fuel flow rate.

Therefore, overshooting and undershooting operations do not occur in the actual fuel flow rate, ignition failure and misfire after ignition are prevented, and the gas turbine plant can be operated extremely stably.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a gas turbine control device according to the present invention, and FIG. 2 is a diagram showing changes in a set fuel flow rate, an actual fuel flow rate, and an actual rotational speed on a time axis according to the above embodiment, FIG. 3 is a configuration diagram of a general gas turbine plant, FIG. 4 is a diagram showing a conventional gas turbine control device incorporated in a general gas turbine plant, and FIG. 5 is a time axis by a conventional gas turbine control device. 5 is a diagram showing changes in the set fuel flow rate, the actual fuel flow rate, and the actual rotation speed of FIG. 13 ... Command control system, 14 ... Low value priority circuit, 16 ... Integral element, 18 ... Proportional element, 29 ... Gas turbine control device, 30
...... Integral element output controller, 31 …… Ignition control system, 32,33
...... Cantilever element, 36 ...... Flow rate set at ignition, 37 ...... Flow rate set after ignition, 38,39,40,41,42 ...... Switch, a ...... Feedback valve opening command, b ... ... Fuel flow rate detection signal, i ...
… Integral element output.

Claims (1)

[Claims] 1. A gas turbine control device for feeding back a detected value of an actual fuel flow rate to a gas turbine combustor, and integrating the difference between the detected value and a set fuel flow rate by an integral element to control the actual fuel flow rate, During and after ignition,
An integral element output control device is provided for forcibly setting the output value of the integral element to obtain the set fuel flow rate and for limiting the output value of the integral element after reaching the set fuel flow rate. A characteristic gas turbine control device.