JPH07139373A - Device and method for controlling gas turbine - Google Patents

Abstract

PURPOSE:To perform stable combustion by a combustor even during cutoff of a load by providing an adder which is constituted to add an output signal from a fundamental lower limit value function generator and an output signal from a bias value function generator to set a result as the fuel flow rate lower limit value of a lower limit limiter. CONSTITUTION:When a fuel flow rate command value is a fuel flow rate lower limit value or less required for maintenance of combustion, limitation is applied on a fuel flow rate command value by a lower limit limiter 14 so that the limiting result is set as a fuel flow rate lower limit value. A fundamental lower limit value is outputted by a fundamental lower limit value function generator 17 based on a fuel flow rate of a fuel injection pump and a compressed air amount of a compressor. A bias value being a fuel flow rate lower limit is outputted by a bias value function generator 18 based on the inlet guide stationary vane angle of the compressor. An adder 19 is provided to add an output signal from the fundamental lower limit value function generator 17 and an output signal from the bias value function generator 18 so that an adding result is set as the fuel flow rate lower limit value of the lower limit limiter. This constitution performs stable combustion at a combustor even when cutoff of a load occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a fuel flow rate from a combustion injection pump of a gas turbine power generation facility by adjusting a fuel bypass valve provided in parallel with the fuel injection pump to control a fuel flow rate supplied to a gas turbine. The present invention relates to a gas turbine control device and method.

[0002]

As is well known, gas turbine power generation facilities are
A compressor that compresses air taken from the atmosphere, a combustor that burns a mixture of air and fuel, a gas turbine that is driven by combustion gas from the combustor, and a generator that is further driven by the gas turbine. And are configured as the main equipment.

On the other hand, the gas turbine control device uses a plurality of control systems such as a speed load control system, an exhaust gas temperature control system, and a startup control system as a high value limit control system, and functionally separates each control system. A method of controlling the fuel to the combustor using a selection circuit for is commonly used.

These gas turbine power generation equipment and its control system are shown in FIGS. 3 and 4. FIG. 3 shows a general configuration example of a gas turbine power generation facility that uses liquid fuel.

The main equipment of the gas turbine power generation equipment to be controlled is a gas turbine 1, a combustor 2, a compressor 3, and a generator 4.
Composed of. In the compressor 3, the air sucked from the atmosphere is compressed and the compressed air is sent to the combustor 2.
On the other hand, the fuel from the fuel injection pump 5 that is coupled to the gas turbine shaft through a gear and that is rotated by the gas turbine power is injected into the combustor 2 as determined by the escape amount of the fuel bypass control valve 6. Then, the compressed air and the fuel are mixed in the combustor 2 and burned to form high-temperature combustion gas, which flows into the gas turbine 1 and is expanded. By this, the gas turbine shaft end power is obtained, and by this power,
The generator 4 is driven to obtain a predetermined electric power.

On the other hand, the fuel bypass control valve 6 is regulated and controlled by the gas turbine control device 7. FIG. 4 shows a typical configuration example of a liquid fuel gas turbine control device. The gas turbine control device 7 includes a speed load control system 1
0, the exhaust gas temperature control system 11, and the control system 12 at the time of starting, a low value priority circuit 13, a lower limit limiter 14, a signal generator 15, and an inverse function generator 16.

The speed load control system 10 outputs a control signal in order to obtain a target generator output and a target rotation speed. The exhaust gas temperature control system 11 sets the exhaust gas temperature corresponding to the restricted gas turbine inlet temperature as a set value, and outputs a limit control signal to prevent a temperature increase above this set value. Then, the startup control system 12 outputs a control signal for performing speed-up control until reaching the rated speed, including ignition and warm-up operations.

Since the minimum value becomes the main control signal due to the characteristic of each control system function, the output signal from each control system is selected by the low value priority circuit 13 and the minimum value is limited. Input to the container 14. On the other hand, the lower limit limiter 14
Is the fuel flow rate from the signal generator 15 which gives an opening degree equivalent signal obtained from the fuel flow rate to air flow rate ratio (hereinafter abbreviated as F / A ratio) required as a limit value for performing combustion in the combustor 2. The lower limit value has been entered. In the lower limit limiter 14,
By comparing these two input signals, the high value is selected and output,
The inverse function generator 16 performs characteristic reversal processing for the fuel bypass control valve, and outputs it as an opening degree instruction signal of the fuel bypass control valve 6.

With the above control circuit configuration, on the input side of the low value priority circuit 13, when any element outputs a command in excess of the other control system provided as a limit in all operating states, The minimum suppression command will be output immediately. Therefore, the fuel control valve-equivalent opening signal is output to safely and efficiently perform the operation. Further, in the lower limit limiter 14, even when the output signal of the low value priority circuit 13 outputs a command to throttle the fuel flow rate in the zero direction, in order to prevent blowout of combustion in the combustor, a signal generator is used as the lower limit limit signal. The output signal of 15 acts, and it becomes possible to continue the safe operation of the gas turbine 1.

[0010]

However, when the load of the gas turbine power generation equipment is cut off, the following problems occur.
That is, when a load cutoff occurs, the load speed control system 10 instantaneously decreases from the load operation equivalent opening command signal immediately before the load cutoff to the no-load rated rotational speed equivalent opening command, and the rotational speed of the gas turbine 1 increases. On the other hand, since it acts to reduce the opening degree instruction signal based on the preset adjustment rate, the output signal of the load speed control system 10 drops to near zero. For this reason, the output of the low value priority circuit 13 is close to zero, so that the lower limit limiter 14 limits the fuel flow rate command to the fuel flow rate lower limit value given for blowout prevention. However, in the process of increasing the number of revolutions after the occurrence of the load shedding, it is necessary to cope with the increase in the fuel flow rate in order to secure the lower limit value of the F / A ratio with the increase in the amount of air flowing into the compressor 3.
Further, it is necessary to take measures to reduce the fuel flow rate as the compressor inflow air amount decreases due to the closing operation of the compressor inlet guide vanes near the rotational speed settling state after the load shedding occurs. Since this measure is not taken, the following inconvenience occurs. Since the liquid fuel supply pump 5 is driven by turbine shaft power,
As the rotation speed increases due to load shedding, the fuel pump 5
The discharge amount of is also increased. At that time, if the rotation speed increasing operation is performed even when the opening degree of the fuel bypass control valve 6 is in the lower limit value state, the diverging state of increasing the rotation speed → increasing the fuel pump discharge amount → increasing the rotation speed is brought to the rated rotation speed. There is a problem that the pull-back operation is not performed.

Therefore, an object of the present invention is to secure the lower limit value of the F / A ratio necessary for stable combustion even when the load is cut off, and to increase the discharge flow rate of the fuel pump due to the increase of the rotation speed. Another object of the present invention is to provide a gas turbine control device and method capable of supplying an amount of fuel required for stable combustion in a gas turbine.

[0012]

The gas turbine control apparatus of the present invention becomes the fuel flow rate lower limit value when the fuel flow rate command value is less than the fuel flow rate lower limit value necessary for maintaining combustion in the combustor. Lower limiter that limits the fuel flow rate command value, and a basic lower limit value function that outputs the basic lower limit value based on the fuel flow rate of the fuel injection pump and the compressed air amount of the compressor that fluctuate due to fluctuations in the gas turbine speed A generator,
Bias value function generator that outputs the bias value of the fuel flow rate lower limit value based on the inlet guide vane angle of the compressor that fluctuates due to load fluctuation of the generator, and the output signal of the basic lower limit value function generator and the bias value function generation And an output signal of the fuel container, and the fuel flow rate lower limit value of the lower limiter is added.

The basic lower limit value function generator is such that the ratio of fuel flow rate to air flow rate in the combustor when the compressor inlet guide vane angle is the angle in the rated load operating state of the generator is the lower limit of stable combustion. And a bias value function generator that stabilizes the fuel flow to air flow ratio in the combustor at the compressor suction flow when the gas turbine speed is the rated speed of the generator. It is configured to generate a value that is the lower limit of combustion.

Further, in place of the basic lower limit value function generator, a signal generator for presetting the basic fuel flow rate lower limit value necessary for maintaining combustion in the combustor is provided. On the other hand, the gas turbine control method of the present invention calculates the basic lower limit value based on the fuel flow rate of the fuel injection pump and the compressed air amount of the compressor, which fluctuates due to fluctuations in the gas turbine speed, and fluctuates depending on load fluctuations in the generator. A bias value of the fuel flow rate lower limit value is calculated based on the inlet guide vane angle of the compressor, the basic lower limit value and the bias value are added, and the fuel flow rate command value is added to the basic lower limit value and the bias value. When it is less than the value, the fuel flow rate command value is used as the added value to control the fuel flow rate.

Further, instead of calculating the basic lower limit value based on the fuel flow rate of the fuel injection pump and the compressed air amount of the compressor which fluctuate due to the fluctuation of the gas turbine speed, in order to maintain combustion in the combustor. The required lower limit of the basic fuel flow rate is set in advance.

[0016]

When the load is cut off and the number of revolutions of the gas turbine rises, a basic lower limit value function is established based on the fuel flow rate of the fuel injection pump and the amount of compressed air of the compressor, which fluctuates due to fluctuations in the number of revolutions of the gas turbine. The generator outputs a basic lower limit value appropriate for that state, and the bias value function generator fluctuates according to the load fluctuation of the generator, and the compressor inlet guide vane angle Based on the above, a bias value of the fuel flow rate lower limit value is output. Then, the adder adds the output signal of the basic lower limit function generator and the output signal of the bias value function generator to obtain the fuel flow rate lower limit value of the lower limit limiter.

[0017]

EXAMPLE An example of the present invention will be described below. FIG. 1 is a block diagram showing an embodiment of the present invention. The basic lower limit value function generator 17 is set with a function that outputs an appropriate basic lower limit value in that state based on the fuel flow rate of the fuel injection pump and the compressed air amount of the compressor that fluctuate due to fluctuations in the gas turbine speed. ing. That is, the basic lower limit function generator 1
Reference numeral 7 is a function for generating a value at which the ratio of the fuel flow rate to the air flow rate in the combustor 2 is the lower limit of stable combustion when the compressor inlet guide vane angle is the angle in the rated load operation state of the generator 4. Is set.

On the other hand, the bias value function generator 18 has a bias suitable for determining the lower limit value of the fuel flow rate in that state based on the inlet guide vane angle of the compressor 3 which fluctuates due to the load fluctuation of the generator 4. A function that outputs a value is set. That is, in the bias value function generator 18, the fuel flow rate to air flow rate ratio in the combustor 2 at the compressor suction flow rate when the gas turbine rotation speed is the rated rotation speed of the generator 4 is the lower limit of stable combustion. The function that generates the value is set.

The output signal of the basic lower limit value function generator 17 and the output signal of the bias value function generator are input to an adder, where they are added and the lower limit limiter 14 is used as the lower limit value of the fuel flow rate. 14 is input.

On the other hand, the fuel flow rate command value from the low value priority circuit 13 is input to the lower limit limiter 14, and the fuel flow rate command value is less than the fuel flow rate lower limit value required to maintain combustion in the combustor 2. In this case, the fuel flow rate command value is limited so that the fuel flow rate lower limit value is reached. Therefore, stable combustion in the combustor 3 can be enabled even when the load is cut off.

As described above, in this embodiment, the basic lower limit value is calculated based on the fuel flow rate of the fuel injection pump 5 and the compressed air amount of the compressor 3 which fluctuate due to the fluctuation of the gas turbine rotation speed, and the basic lower limit value of the generator 4 is calculated. The bias value of the fuel flow rate lower limit value is calculated based on the inlet guide vane angle of the compressor 3 which varies due to load fluctuation, and the basic lower limit value and the bias value are added so that the fuel flow rate command value becomes the basic lower limit value and the bias value. When it is less than the addition value of the fuel flow rate and the fuel flow rate command value, the fuel flow rate is controlled.

That is, the basic lower limit function generator 17 is
Using the gas turbine speed as a reference signal, the value at which the F / A ratio of the combustor at the compressor suction flow rate when the compressor inlet guide vane angle is at the rated load operating condition is the lower limit of stable combustion is A function that takes into account the increase in the fuel injection pump discharge pressure that fluctuates when the rotation speed increases or decreases and the compressor inflow air flow rate is set, and the fuel control valve opening command signal that corresponds to the input state quantity of the gas turbine rotation speed. Is output.
On the other hand, the bias value function generator 18 uses the inlet guide vane angle of the compressor 3 as a reference signal, and the F / A ratio of the combustor 2 at the suction flow rate of the compressor 3 at the gas turbine speed is the rated speed. When the lower limit of stable combustion is set to zero, the F / A ratio of the combustor becomes the lower limit of stable combustion when the gas turbine speed is the rated speed and the inlet guide vane angle of the compressor 3 is at the maximum opening. A bias value corresponding to the fuel control valve opening corresponding to the fuel amount is set, and a fuel control valve opening command signal corresponding to the input state quantity of the inlet guide vane angle of the compressor 3 is output. The signals output from the respective function generators 17 and 18 are input to the adder 19, and after addition operation, input to the lower limit limiter 14.

In the basic value function generator 17 using the gas turbine speed as a reference signal, the F / A ratio, which is the lower limit at the rated speed of the inlet guide vane, is set, and the compressor inlet variable vane angle is referred to. The bias value function generator 18 used as a signal is
It functions as a bias setting function of the lower limit F / A ratio that changes with the compressor inflow air flow rate that increases and decreases due to the operation of the variable inlet stationary vanes of the compressor 3, and by adding the output signals of the respective function generators 17 and 18. Acts as a lower bound for the total.

Next, another embodiment is shown in FIG. The difference from the embodiment of FIG. 1 is that, in place of the basic lower limit function generator 17 that uses the gas turbine speed as a reference signal, a signal that presets the basic lower limit value required to maintain combustion in the combustor 2. The generator 15 is provided, and by adding this output signal and the output signal of the bias value function generator 18 using the compressor inlet variable stator vane angle as a reference signal, the lower limit limiter 14
You are typing in. Also in this case, it is possible to obtain the same result as the configuration shown in FIG.

[0025]

As described above, according to the present invention,
When a load cutoff occurs in the gas turbine control device when using liquid fuel, a function is provided that corresponds to the increase or decrease of the fuel pump discharge pressure due to the increase or decrease of the rotation speed and the increase or decrease of the air flow rate into the compressor. By setting the bias to continue stable combustion according to the change of the compressor inlet variable stator vane angle, the combustion does not blow out in the combustor even when the load is cut off, and the fuel flow rate Increase in fuel amount by limiting the number of refining → increase in rotation speed →
It is possible to safely control the fuel flow rate when the load is cut off, without causing divergence such as an increase in the fuel amount.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

[Fig. 3] System configuration diagram showing a gas turbine power generation facility

FIG. 4 is a block diagram showing a conventional example.

[Explanation of symbols]

 1 gas turbine 2 combustor 3 compressor 4 generator 5 fuel pump 6 fuel bypass control valve 7 controller 8 compressor inlet variable vane angle detector 9 gas turbine speed detector 10 load speed control system 11 worship gas temperature control System 12 Control system at start-up 13 Low value priority circuit 14 Lower limiter 15 Signal generator 16 Inverse function generator 17 Basic lower limit function generator 18 Bias value function generator 19 Adder

Claims (6)

[Claims] 1. A compressor directly connected to a gas turbine for compressing air, a fuel injection pump directly connected to the gas turbine for supplying fuel, and the fuel is burned with the compressed air to the gas turbine. A fuel bypass valve provided in parallel with the fuel injection pump to control the fuel flow rate from the fuel injection pump of a gas turbine power generation facility including a combustor that gives a driving force and a generator driven by the gas turbine. In the gas turbine control device which is adapted to control the fuel flow rate to be supplied to the gas turbine, when the fuel flow rate command value is less than the fuel flow rate lower limit value necessary to maintain combustion in the combustor, A lower limit limiter for limiting the fuel flow rate command value to a fuel flow rate lower limit value, and the fuel that fluctuates due to fluctuations in the gas turbine rotation speed A basic lower limit value function generator that outputs a basic lower limit value based on the fuel flow rate of the injection pump and the compressed air amount of the compressor, and based on the inlet guide vane angle of the compressor that fluctuates due to load fluctuation of the generator Bias value function generator for outputting the bias value of the fuel flow rate lower limit value, and the output signal of the basic lower limit value function generator and the output signal of the bias value function generator are added to the fuel flow rate of the lower limiter. A gas turbine control device, comprising: an adder having a lower limit value. 2. The basic lower limit function generator has a fuel flow rate to air flow rate ratio in the combustor when the compressor inlet guide vane angle is an angle in a rated load operation state of the generator. The gas turbine control device according to claim 1, wherein a value that is a lower limit of stable combustion is generated. 3. The bias value function generator has a stable fuel flow rate to air flow rate ratio in the combustor at the compressor suction flow rate when the gas turbine rotation speed is the rated rotation speed of the generator. The gas turbine control device according to claim 1, wherein a value that is a lower limit of is generated. 4. A compressor directly connected to the gas turbine for compressing air, a fuel injection pump directly connected to the gas turbine for supplying fuel, and the fuel is burned together with the compressed air to the gas turbine. A fuel bypass valve provided in parallel with the fuel injection pump to control the fuel flow rate from the fuel injection pump of a gas turbine power generation facility including a combustor that gives a driving force and a generator driven by the gas turbine. In the gas turbine control device which is adapted to control the fuel flow rate to be supplied to the gas turbine, when the fuel flow rate command value is less than the fuel flow rate lower limit value necessary to maintain combustion in the combustor, A lower limit limiter for limiting the fuel flow rate command value so as to be the fuel flow rate lower limit value, and a basic fuel flow rate necessary for maintaining combustion in the combustor. A signal generator whose lower limit value is predetermined,
A bias value function generator that outputs a bias value of the fuel flow rate lower limit value based on the inlet guide vane angle of the compressor that changes due to load fluctuations of the generator, an output signal of the signal generator, and a bias value function. A gas turbine control device, comprising: an adder for adding the output signal of the generator to the fuel flow rate lower limit value of the lower limiter. 5. A compressor directly connected to the gas turbine for compressing air, a fuel injection pump directly connected to the gas turbine for supplying fuel, and the fuel is burned together with the compressed air to the gas turbine. A fuel bypass valve provided in parallel with the fuel injection pump to control the fuel flow rate from the fuel injection pump of a gas turbine power generation facility including a combustor that gives a driving force and a generator driven by the gas turbine. In a gas turbine control method for adjusting the fuel flow rate to be supplied to the gas turbine, based on a fuel flow rate of the fuel injection pump and a compressed air quantity of the compressor, which fluctuate due to fluctuations in the gas turbine rotation speed. To calculate a basic lower limit value, and based on the inlet guide vane angle of the compressor that fluctuates due to load fluctuations of the generator, the fuel flow rate A bias value of the lower limit value is calculated, the basic lower limit value and the bias value are added, and when the fuel flow rate command value is less than the added value of the basic lower limit value and the bias value, the fuel flow rate command value is set. A gas turbine control method, wherein the fuel flow rate is controlled as the added value. 6. A compressor directly connected to the gas turbine for compressing air, a fuel injection pump directly connected to the gas turbine for supplying fuel, and the fuel is burned together with the compressed air to the gas turbine. A fuel bypass valve provided in parallel with the fuel injection pump to control the fuel flow rate from the fuel injection pump of a gas turbine power generation facility including a combustor that gives a driving force and a generator driven by the gas turbine. In a gas turbine control method for adjusting the fuel flow rate to be supplied to the gas turbine, a basic fuel flow rate lower limit value necessary for maintaining combustion in the combustor is predetermined, and a load fluctuation of the generator is determined. Bias value of the fuel flow rate lower limit value is calculated based on the inlet guide vane angle of the compressor, which is changed by When the fuel flow rate command value is less than the added value of the basic fuel flow rate lower limit value and the bias value, the fuel flow rate command value is used as the added value to control the fuel flow rate. A method for controlling a gas turbine, comprising: