JPH0734906A - Gas turbine control device - Google Patents

Abstract

PURPOSE:To enable stable combustion, even at the time of system frequency variation in the governor-free operation, by controlling a pilot distribution valve and a main distribution valve by a signal corresponding to a load request signal not including minute variation. CONSTITUTION:A gas turbine control device is provided with a first low-value priority device 25 in which a load-speed control signal (a) and an exhaust gas temperature restricting control signal (b) are input and either signal of the lower value is output to a fuel flow control valve 9. The device is also provided with a second low-value priority device 29 in which a speed setting signal (f) and the exhaust gas temperature restricting control signal (b) are input and either of the lower value is output as a control signal for controlling a pilot distribution valve 10 and a main distribution valve 11 in a prescribed distribution ratio. In this way, the speed setting signal (f) is output from the second low-value priority device 29 during the speed regulating operation for controlling the pilot and main distribution valves in a prescribed distribution ratio. Even if the fuel flow control valve 9 fluctuates slightly, there is no minute fluctuation in the control signal for controlling the pilot distribution valve 10 and the main distribution valve 11, so that there is few mutal interference with the fuel flow control valve 9 and stable combustion can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine controller for controlling fuel supply to a two-stage combustion type gas turbine combustor so as to obtain good combustion performance.

[0002]

2. Description of the Related Art In recent years, gas turbine equipment has adopted a two-stage combustion low NO _X combustor by a combination of premixed combustion and diffusion combustion in order to reduce the NO _X concentration discharged due to environmental regulations. There is.

FIG. 2 shows an example of a general configuration of a gas turbine facility equipped with a premixed combustor.

The illustrated gas turbine equipment comprises a compressor 1, a combustor 2, a gas turbine 3, a generator 4 and a controller 5, and the combustor 2 is connected to a fuel source (not shown). A pilot pipe 7 branched from the pipe 6 and a main pipe 8 are connected, a fuel flow control valve 9 is arranged in the fuel pipe 6, a pilot distribution valve 10 in the pilot pipe 7, and a main distribution valve in the main pipe 8. 11 are arranged respectively.

First, the air sucked from the atmosphere is compressed by the compressor 1 and sent to the combustor 2. In the combustor 2, the fuel supplied through the pilot distribution valve 10 for supplying the fuel for diffusion combustion and the main distribution valve 11 for supplying the fuel for premixed combustion and the compressed air are mixed and burned to generate a high temperature. The combustion gas of (1) flows into the gas turbine 3 and is expanded to generate power, drive the generator 4, and output electric power.

The total fuel flow rate in the fuel pipe 6 is increased / decreased by opening / closing the fuel flow rate control valve 9 in response to a control signal from the control device 5, and the fuel flow rate for diffusion combustion in the pilot pipe 7 and the premixed combustion in the main pipe 8 are mixed. The ratio to the fuel flow rate for use is controlled by increasing / decreasing by opening / closing the pilot distribution valve 10 and the main distribution valve 11 according to a control signal from the control device 5. In this way, the controller 5 is controlling the respective equipment in order to reduce the predetermined power generation output and the gas turbine exhaust gas or NO _X.

Next, the control device 5 will be specifically described with reference to FIG.

The controller 5 is roughly divided into an integrator 12
Change rate limiter 13, subtractor 14, MW detector 15, integrator 16, subtractor 17, speed detector 18, and proportional calculator 1
Load speed control system consisting of 9 and compressor discharge pressure detector 20
, Function generator 21, subtractor 22, exhaust gas temperature detector 23
And a proportional / integrator 24.

Then, the load speed control signal a of the load speed control system and the exhaust gas temperature limit control signal b of the exhaust gas temperature limit control system are input to the low value priority device 25, and the low value signal c of the low value priority device 25 is used. The fuel flow rate control valve 9 is controlled, and further, the low value signal c of the low value priority device 25 controls the pilot distribution valve 10 via the function generator 26, and the output signal of the function generator 26 and the output of the setter 27. The signal and the signal are added by the adder 28, and the main distribution valve 11 is controlled by the added signal.

First, in the load speed control system, the load target is given to the integrator 12, and the output signal of the integrator 12 is input to the subtractor 14 via the change rate limiter 13. Subtractor 14
Then, the integrator 16 that is subjected to subtraction processing with the actual generator output signal of the MW detector 15 and the deviation signal functions as a speed setter 16
Is input to and integrated processing is performed.

The output signal of the integrator 16 is given to the subtractor 17 as a speed setting signal. In the subtractor 17, the speed setting signal f and the gas turbine speed signal of the speed detector 18 are subjected to subtraction processing, and a proportional element is calculated. It is multiplied by the coefficient in the proportional calculator 19 that it has, and is input to the low value priority device 25 as the load speed control signal a.

On the other hand, the detection signal of the compressor discharge pressure detector 20 is given to the function generator 21, and the exhaust gas temperature limit value for the compressor discharge pressure is calculated. The calculated exhaust gas temperature limit value signal is input to the subtractor 22, is subjected to subtraction processing with the detection signal of the exhaust gas temperature detector 23, and is subjected to proportional-plus-integral calculation by the proportional-integrator 24. The limit control signal b is input to the low value priority device 25.

In the low value priority device 25, the load speed control signal a
One of the two values of the exhaust gas temperature limit control signal b and the low value signal c is selected and output as a control signal to the fuel flow rate control valve 9 while being output to the function generator 26.

The function generator 26, as shown in FIG. 4, corresponds to the low value signal c of the low value priority device 25 and the pilot distribution valve 1
The command signal to 0 is preset, and the command signal d is output to the pilot distribution valve 10.

This function generator 26 outputs a low value signal c of about 6
The command signal d is output 100% up to 0%, and the command signal d is sharply decreased when the low value signal c is from about 60% to about 70%, and gradually decreased when it is more than that. ing.

This command signal d is further input to the subtractor 28, subjected to subtraction processing with the signal (100%) given by the setting device 27, and output as the opening command signal of the main distribution valve 11. .

As described above, the opening degree setting of the pilot distribution valve 10 is given by the function generator 26, whereas the opening degree setting of the main distribution valve 11 is performed by the function generator 26 from the 100% opening degree set value. The opening degree obtained by subtracting the given opening degree setting value, that is, the opening degree setting for performing the reverse operation to the pilot distribution valve 10 is output.

As a result, the opening degree of the fuel flow control valve 9 in the middle,
That is, up to a partial load, only diffusion combustion that can perform stable combustion is performed. Above a certain load, the diffusion combustion fuel is throttled and the premixed combustion fuel is increased.

The fuel flow rate characteristic obtained in this way is that the power generation output is about 60%, the first stage fuel is the fuel for diffusion combustion supplied from the pilot distribution valve 10, and the power generation output is about 6%.
When it becomes 0% or more, the first stage fuel is throttled and the main distribution valve 11
The characteristics of the second-stage fuel by the premixed combustion fuel are increased. As a result, NO _X under a high load can be significantly reduced.

[0020]

However, in the control device 5 of the above-mentioned two-stage combustion gas turbine equipment, when the system frequency slightly changes due to various factors, the fuel flow control valve 9, the pilot distribution valve 10, and the main distribution valve. There is the following problem that each opening of the valve 11 fluctuates oscillatingly.

That is, governor-free control of a thermal power plant can be cited as one of the causes of load stability in recent years. Along with this, when power plants in the same grid operate at the same power regulation rate, when the load increases or decreases in a short cycle, the power generation output is increased or decreased instantaneously according to the fluctuation of the frequency of the grid. The power plants in the same grid are governor-free controlled, and the frequency on the grid is stabilized.

However, the system frequency fluctuates subtly due to various factors. In particular, the output of the power plant cannot handle the load change in a nuclear power plant or a system in which a high proportion of coal-fired power plants occupy. Therefore, the system stability is poor and the system frequency swings widely.

In the case of the two-stage combustion gas turbine equipment having the control system shown in FIG. 2 and FIG. 3, when the system frequency slightly fluctuates, the load speed control signal a becomes very small in order to perform speed control. First, the fuel flow control valve 9
The opening degree of changes. As a result, the fuel flow control valve 9 and the pilot distribution valve 10 arranged in series interfere with each other and the opening of the pilot distribution valve 10 fluctuates greatly. Similarly, the opening degree of the main distribution valve 11 arranged in series with the fuel flow rate control valve 9 also greatly changes. The vibration of the main distribution valve 11 in a short cycle causes instability of the combustion flame, causes combustion vibration, causes blowout, and interferes with the diffusion combustion flame to each other, and the fluctuation of the internal pressure causes the entire combustor to be exhausted. Has a problem that it vibrates.

Therefore, an object of the present invention is to provide a gas turbine control device capable of performing stable combustion even when the system frequency fluctuates during governor-free operation.

[0025]

According to the present invention, there is provided a pilot distribution valve and a main distribution valve respectively provided in a pilot pipe and a main pipe branched from a fuel pipe having a fuel flow rate control valve for controlling a total flow rate from a fuel supply facility. In a gas turbine control device for controlling gas turbine equipment for controlling a valve and a control signal with a predetermined distribution ratio to supply a predetermined proportion of fuel to a two-stage combustion combustor, a load target for speed control operation A means for calculating the speed setting signal from the request and the actual power generation output signal, a means for calculating the load speed control signal from the speed setting signal and the speed detection signal, and a compressor discharge pressure signal for limiting the rise of the exhaust gas temperature. And a means for calculating an exhaust gas temperature limit signal from the exhaust gas temperature detection signal, and inputting the load speed control signal and the exhaust gas temperature limit control signal. A first low value priority device that outputs a signal of a deviation or a low value to the fuel flow valve, and the speed setting signal and the exhaust gas temperature limit control signal are input, and a signal of either low value is input to the pilot distribution valve. And a second low value priority device for outputting the main distribution valve as a control signal with a predetermined distribution ratio.

[0026]

With the above structure, the speed setting signal is output from the second low value priority device during the speed control operation, and the pilot distribution valve and the main distribution valve are controlled at a predetermined distribution ratio based on the speed setting signal. At this time, since the speed setting signal is a signal corresponding to the load request signal that does not fluctuate including a minute fluctuation, control that controls the pilot distribution valve and the main distribution valve even if the fuel flow control valve fluctuates slightly. Since there is no slight fluctuation in the signal, there is little mutual interference with the fuel flow control valve, and stable combustion can be performed.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a gas turbine control system showing an embodiment of the present invention. The same reference numerals as those in FIG. 3 showing the conventional example indicate the same or corresponding portions, and the difference between FIG. 1 and FIG. 3 is that the speed setting signal f of the integrator 16 and the exhaust gas temperature limit control signal system of the load speed control signal system are different. Of the pilot distribution valve 1 based on the low value signal g.
0 and the opening degree of the main distribution valve 11 are controlled.

With the above configuration, the integrator 1 that functions as a speed setter of the load speed control system during governor-free operation
While the speed setting signal f of 6 is selected as the low value signal g by the low value priority device 29, during the exhaust gas temperature limit control,
The exhaust gas temperature limit control signal b of the proportional / integrator 24 is selected as the low value signal g by the low value priority device 29. This low-value signal g is given as an input signal to the function generator 26 to control the pilot distribution valve 10 and the main distribution valve 11.

In this case, the speed setting signal f of the integrator 16 of the load speed control system temporarily increases or decreases in accordance with the load command that does not include the generated speed deviation including the fluctuation of the gas turbine speed. It is the load demand. Therefore, the speed setting signal f of the integrator 16 which does not include the vibration component is selected as the low value signal g even during the governor-free operation, and the function generator 2
6 is input.

The function generator 26 outputs a command signal d1 to the pilot distribution valve 10 in response to the low value signal g by the function setting shown in FIG. 4 to increase or decrease the opening of the pilot distribution valve 10. The signal d1 is a smooth signal that does not include slight vibration fluctuations, and the opening of the pilot distribution valve 10 is slowly increased or decreased.

Next, the command signal d1 of the function generator 26 is input to the subtractor 28 and is subtracted from the output signal of the setter 27 for setting 100% by the symbol shown in the figure, and the output signal of the subtractor 28 is the command signal. Although the command signal e1 is input to the main distribution valve 11 as e1 and the opening degree of the main distribution valve 11 is increased or decreased, the command signal e1 is a smooth signal that does not include fluctuations in microvibration. It is slowly increased or decreased.

As described above, during the governor-free operation, the pilot distribution valve 10 is operated by the speed setting signal f of the integrator 16 which functions as a speed setting device in the load speed control system.
Since the main distribution valve 11 and the main distribution valve 11 are controlled, the control valve is controlled without being affected by the fluctuation even when the system frequency slightly fluctuates.

[0034]

As described above, according to the present invention, since the pilot distribution valve and the main distribution valve are controlled by the signal according to the load request signal which does not include minute fluctuations, the fuel flow rate control valve is small. Even if it fluctuates, there is little mutual interference between the pilot distribution valve and the main distribution valve with the fuel flow rate control valve, and stable combustion can be performed.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a gas turbine control device showing an embodiment of the present invention.

FIG. 2 is a system diagram of a two-stage combustion system gas turbine facility.

FIG. 3 is a block diagram of a conventional gas turbine control device corresponding to FIG. 1.

FIG. 4 is an explanatory diagram showing a function of a function setter for the pilot distribution valve of FIG. 3.

5 is an explanatory diagram showing fuel flow rate characteristics under the control of the gas turbine control device of FIG. 3. FIG.

[Explanation of symbols]

 1 Compressor 2 Combustor 3 Gas Turbine 4 Generator 5 Control Device 6 Fuel Pipe 7 Pilot Pipe 8 Main Pipe 9 Fuel Flow Control Valve 10 Pilot Distribution Valve 11 Main Distribution Valve 12 Integrator 13 Change Rate Limiter 14 Subtractor 15 MW Detector 16 Integrator 17 Subtractor 18 Speed detector 19 Proportional calculator 20 Compressor discharge pressure detector 21 Function generator 22 Subtractor 23 Exhaust gas temperature detector 24 Proportional / integrator 25 Low value priority device 26 Function generator 27 Setter 28 Subtractor 29 Low value priority device

Claims (1)

[Claims] 1. A pilot distribution valve and a main distribution valve respectively provided in a pilot pipe and a main pipe branched from a fuel pipe having a fuel flow rate control valve for controlling a total flow rate from a fuel supply facility, according to a predetermined distribution ratio. In a gas turbine control device that controls gas turbine equipment that supplies a predetermined proportion of fuel to a two-stage combustion combustor by controlling with a control signal, a load target request and an actual power generation output signal are used to control the speed. From the means for calculating the speed setting signal, the means for calculating the load speed control signal from the speed setting signal and the speed detection signal, and the compressor discharge pressure signal and the exhaust gas temperature detection signal in order to limit the rise in the exhaust gas temperature. A means for calculating an exhaust gas temperature limit signal, a signal having a lower value by inputting the load speed control signal and the exhaust gas temperature limit control signal A first low-value priority device that outputs to the fuel flow rate control valve, and the speed setting signal and the exhaust gas temperature limit control signal are input, and a signal of either low value is input to the pilot distribution valve and the main distribution valve. And a second low value prioritizer for outputting as a control signal for controlling the above-mentioned value according to a predetermined distribution ratio.