JP2003239763A - Governor-free control method and control device of gas turbine generation equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a multi-axial combined gas turbine generation equipment of the parallel operation with main equipment, especially a gas turbine generator mounting a low NOx burner for the premix combustion so that the safe operation condition of the gas turbine, especially the fuel/air ratio of the low NOx burner satisfies an allowable value when the quantity of the fuel to be fed to the gas turbine is adjusted to compensate the variation of the system frequency. <P>SOLUTION: In the governor-free control method of the gas turbine generation equipment for adjusting a fuel quantity command signal so that the deviation between a generation quantity command signal of the gas turbine generation equipment and an actual generation quantity signal of the generation equipment is zero and for adjusting the generation quantity command signal by inputting a system frequency signal, the rate of change of the inputted system frequency signal is limited and the generation quantity command signal is adjusted by the signal whose rate of change is limited. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a governor-free control method and a governor-free control device for a multi-shaft combined gas turbine power generation facility which is premised on grid-connected operation, and more particularly to compensating for fluctuations in system frequency. In addition, the present invention relates to a control method and device for adjusting a fuel amount command signal while maintaining a stable operating state of power generation equipment.

[0002]

2. Description of the Related Art Conventionally, system interconnection operation in a thermal power generation facility has been carried out as follows. In pulverized coal-fired steam power generation, since the boiler has a large heat capacity, the governor-free operation is performed by adjusting the amount of steam supplied to the steam turbine according to system frequency fluctuations, which is equivalent to the boiler of a gas turbine power generation facility. Since the combustor is a machine that recovers power by expanding the high temperature and high pressure combustion gas obtained by the combustion reaction in a short time, the system frequency is adjusted by controlling the amount of fuel input.

Further, in the pulverized coal burning and gas turbine power generation equipment, since the turbine rotating shaft and the generator are connected, the load of the power generation equipment also changes according to the fluctuation of the system frequency. For example, when the system frequency drops, the rotation speed also drops, and in order to maintain the specified rotation speed, it is necessary to increase the supplied fuel amount in the gas turbine power generation equipment. On the contrary, when the system frequency becomes high, the number of rotations is increased and it is necessary to reduce the supplied fuel amount. If the system frequency fluctuation period is as large as several minutes, frequency control operation (AFC: Automatic Frequency C
Although the ontro1) is performed, the load cannot be instantaneously followed due to the delay of the control operation end of the power generation equipment or the delay of the combustion reaction because the cycle is several Hz during governor-free operation. In particular, in the case of multi-axis combined power generation equipment, generators are often connected to each of the target multiple gas turbines, and system frequency fluctuations directly affect the gas turbine rotation speed. Becomes

A conventional governor control method will be described. The actual MW signal (MW) that shows the actual output at the power generation facility,
MWD (Mega Watt De
The deviation from the (mand) signal (MW) is calculated by the first subtracter, and the analog memory which inputs the obtained deviation outputs the load increase / decrease command so that the load deviation becomes zero. In this analog memory, the rate of change that allows the corresponding power generation equipment to stably follow the load is set in advance. The output of the analog memory is converted from the load deviation signal (MW) to the gas turbine rotation speed signal (% SPD) by the first gain setting device, and then transmitted to the second subtractor. The actual rotation speed signal (rpm) is converted into a speed signal (% SPD) by the second gain setting device, and the rated rotation speed (100%) is set in the first constant setting device.
After the deviation from the second subtractor 7 is calculated by the third subtractor 7,
Transmitted to. The output of the second subtractor is the speed signal (%
After the SPD) is converted into the fuel amount command signal (FFD), the fuel command signal at the no-load rated speed set in the second constant setter is added by the first adder. The output signal of the first adder is input to the low value selector. The governor control signal from the adder 9 is fed to the low value selector by several% to
Load limiter control signal 2 added for 10% load
2 and the exhaust temperature control signal adjusted by the exhaust temperature of the gas turbine equipment are input, and the lowest value of the three signals is selected to control the gas turbine fuel related valve as the governor control command signal 24. Here, the load limiter control signal is, for example, when the actual MW signal or the rotation speed signal suddenly changes and the fuel command value suddenly increases, the fuel limit value is increased by the addition signal corresponding to the load of several to 10%. The purpose is to suppress the input. In addition, the exhaust temperature control signal should prevent excessive fuel injection when the exhaust temperature exceeds a preset value in response to a sudden increase in exhaust temperature that occurs when abnormal combustion occurs in the combustor of the gas turbine. The purpose is.

On the other hand, recent gas turbine combustors are equipped with low NOx combustors using premixed combustion. Premixed combustion reduces the heat N0x generated by combustion,
Set the fuel-air ratio defined by the mass ratio of fuel and combustion air to 2
It is designed to operate at ~ 3%. for that reason,
When the stable combustion range is narrower than that of normal diffusion combustion and the governor-free operation is carried out in a gas turbine power generation facility equipped with a low NOx combustor, a dynamic balance between the combustion air amount and the fuel, that is, It is necessary to keep the fluctuation of the fuel-air ratio in the process of changing the fuel amount or the combustion air amount within the allowable range. The conventional control method described above does not provide a system for keeping the fuel-air ratio within the allowable range in the process of changing the fuel amount or the combustion air amount.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a multi-shaft combined gas turbine power generation facility for system interconnection operation, and more particularly to a gas turbine generator equipped with a low NOx combustor for premixed combustion, in which the system frequency When adjusting the fuel supply amount to the gas turbine to compensate for the fluctuation,
The object is to control so that the stable operating conditions of the gas turbine, in particular, the fuel-air ratio of the low NOx combustor satisfies an allowable value.

[0007]

[Means for Solving the Problems] As described above, when the system frequency fluctuates and the fuel amount is changed in accordance with the fluctuation, when the system frequency fluctuates rapidly, the supply of combustion air is supplied. In some cases, the change in the amount of fuel cannot follow the change in the amount of fuel. This is because the operation of the means for adjusting the supply amount of combustion air and the speed of change of the supply amount of combustion air accompanying it are faster than the speed of the operation of the fuel amount adjustment valve and the change in fuel supply amount accompanying it. Because it is late.

In order to achieve the above object, the inventors have
As a result of various studies, the system frequency was input in order to avoid the fuel-air ratio variation due to the time difference between the change in the fuel supply amount when the system frequency fluctuates and the accompanying change in the combustion air supply amount. At this time, it has been conceived to reduce the time difference by reducing the sensitivity to the fluctuation of the system frequency that is an input for adjusting the fuel supply amount.

That is, the means of the present invention for achieving the above object adjusts the fuel amount command signal so that the deviation between the power generation command signal of the gas turbine power generation facility and the actual power generation signal of the power generation facility becomes zero. Along with, in a governor-free control method for a gas turbine power generation facility that adjusts the power generation command signal by inputting a system frequency signal, the rate of change of the input system frequency signal is limited, and the change rate is limited by the signal. The power generation amount command signal is adjusted.

The above-mentioned means may be provided with a system frequency fluctuation suppressing filter means for removing small fluctuations of a cycle equal to or shorter than a desired cycle contained in the input system frequency signal.

The input system frequency signal is
It is desirable to use it for adjusting the power generation amount command signal after passing through the first-order lag element for which the dead time is set.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 shows a control system diagram of governor control when the present invention is applied to governor control of a multi-axis combined gas turbine power generation facility. The part surrounded by the broken line in FIG.
The part related to the present invention, and the part outside the broken line frame shows a conventional governor control system.

The control device shown in the figure is connected to a first subtractor 4 to which an actual MW signal 1 indicating the actual power generation amount of the power generation equipment is input to one input side, and to the output side of the first subtractor 4. And an analog memory 5, a first gain setting device 6 to which the output of the analog memory 5 is input, a second subtractor 7 having one output of the output of the first gain setting device 6, and a second A third gain setting unit 8 having the output of the subtractor 7 as an input, an adder 9 having the output of the third gain setting unit 8 as an input, a constant setting unit 10 connected to the adder 9, and an addition Low value selector 11 connected to the output side of the device 9 and MWD (Mega Watt Deman
d) an adder 12 to which the signal 2 is input, a change rate setting device 13 having an input side connected to the output side of the adder 12 and an output side connected to the other input side of the first subtractor 4, System frequency fluctuation suppression filter means 16 to which the system frequency signal 3 is input
A dead zone setting device 17 connected to the output side of the system frequency variation suppression filter means (hereinafter referred to as variation suppression filter means) 16; and a change rate setting device 18 connected to the output side of the dead zone setting device 17. The input side is the output side of the change rate setting device 18, the output side is the first-order lag element 15 connected to the adder 12, and the suppression rate setting device connected to the change rate setting device 13 and the change rate setting device 18. 14, a second gain setting device 19 to which the rotation speed signal 25 is input, and the second gain setting device 19.
And a third subtractor 20 having one input side connected to the output side of the gain setter 19 and the output side connected to the other input side of the second subtractor 7, and a third subtractor 20. And a constant setter 21 connected to the other input side of.

In addition to the output of the adder 9, the low value selector 11 also has a load limiter control signal 22 which is added to the governor control signal from the adder 9 by a load corresponding to several% to 10%. An exhaust temperature control signal 23 adjusted according to the exhaust temperature of the gas turbine equipment is input.

The dashed line in FIG. 1 includes the adder 12, the change rate setting unit 13, the suppression rate setting unit 14, the first-order lag element 15, the system frequency fluctuation suppression filter means 16, the dead zone setting unit 17, and the change rate setting unit 18. A speed adjustment suppression bias means shown by a frame is configured.

Next, the operation of the control device having the above configuration will be described. First, the actual MW signal 1 that shows the actual output of the power generation equipment
The deviation obtained by subtracting (MW) from the signal obtained by correcting the MWD signal 2 (MW) of the output command value from the central power supply command station using the system frequency signal 3 (the details of this correction will be described later) is It is calculated by the subtracter 4, and the analog memory 5 outputs a load increase / decrease command so that the load deviation becomes zero. In the analog memory 5, a rate of change is set beforehand so that the corresponding power generation equipment can stably follow the load. The output of the analog memory 5 is converted from a load deviation signal (MW) into a gas turbine rotation speed signal (% SPD) by the first gain setting device 6, and then the second subtractor 7
Transmitted to.

The actual rotation speed signal 25 (rpm) is the second
Is converted to a speed signal (% SPD) by the gain setting device 19 of the motor and the rated rotation speed (10
0%) is calculated by the third subtractor 20 and then the second
Is transmitted to the subtractor 7. The subtractor 7 subtracts the output of the third subtractor 20 from the output of the first gain setting device 6,
The obtained deviation is output to the third gain setter 8. Third
In the gain setter 8 of No. 2, the adjustment factor of the power generation equipment is set, and the input deviation (speed signal (% SPD)) is converted into the fuel amount command signal (FFD) and then output to the adder 9. . The adder 9 adds the fuel command signal at the no-load rated speed set in the constant setter 10 to the input fuel amount command signal (FFD), and then transmits it to the low value selector 11.

To the low value selector 11, as described above,
To the governor control signal from the adder 9, a load limiter control signal 22 added by a load equivalent to several% to 10% and an exhaust temperature control signal 23 adjusted by the exhaust temperature of the gas turbine equipment are input. The lowest value of the three signals is selected and the governor control command signal 24 controls the gas turbine fuel related valve. Here, the load limiter control signal 22 is, for example, when the actual MW signal 1 or the rotation speed signal 25 suddenly changes and the fuel command value suddenly increases, by the addition signal corresponding to the load of several% to 10% described above. The purpose is to suppress excessive injection of fuel. In addition, the exhaust temperature control signal should prevent excessive fuel injection when the exhaust temperature exceeds a preset value in response to a sudden increase in exhaust temperature that occurs when abnormal combustion occurs in the combustor of the gas turbine. The purpose is.

Next, the output command value from the central power supply command station
A procedure for correcting the MWD signal 2 (MW) using the system frequency signal 3 will be described. This correction is performed by the configuration within the broken line frame in FIG.
That is, it is performed by the speed adjustment suppression bias means.

The system frequency signal 3 is very small (for example, 0.01 to 0.03) by the fluctuation suppressing filter means 16.
After removing the frequency fluctuation component (about Hz), it is transmitted to the dead zone setting unit 17. The dead zone setting device 17 is provided with a control operation end of the target gas turbine power generation equipment, for example, wear due to a minute operation of a fuel amount adjusting valve, a combustion air amount adjusting device, or deterioration of a spring, and the like. A value suitable for reducing the remaining life consumption of is set. The output signal of the dead zone setting device 17 is transmitted to the first-order lag element 15 via the rate-of-change setting device 18, passed through the first-order lag element 15 and delayed, and then added by the adder 12 to the MWD.
It is added to the signal 2 as a bias signal.

In the first-order lag element 15, a fuel supply command signal to the gas turbine power generation equipment, which is adjusted by increasing / decreasing the output deviation signal calculated by the first subtractor 4, is supplied to the gas turbine power generation equipment. A time constant is set that is suitable for following the load while maintaining stable operation conditions. The output signal of the adder 12 is transmitted to the first subtractor 4 via the change rate setting device 13. The two change rate setting devices 13 and 1
In 8, a change rate value suitable for the operating state quantity of the target gas turbine power generation facility to fall within the stable allowable range is manually set by the suppression rate setting unit 14.

The contents of the fluctuation suppressing filter means 16 in FIG. 1 will be described below with reference to FIG. System frequency signal 3
Is the rotation speed signal (% SPD) by the gain setter 26.
And is transmitted to the first-order delay element 27, the switch 32, and the subtractor 28. The rotational speed signal, that is, the frequency signal, is converted to a small and gentle fluctuation component by the time constant preset in the first-order lag element 27, and then transmitted to the switch 32 and the subtractor 28. It The subtractor 28 subtracts the output signal of the gain setting device 26 from the output signal of the first-order lag element 27, and outputs the calculation result to the comparator 30 via the absolute value calculator 29.
The comparator 30 outputs a signal 0 when the input from the absolute value calculator 29 is less than or equal to a preset allowable value of frequency fluctuation.
Is output, and in the opposite case, 1 is output. This output is input as a switching signal to the switch 32 via the dead time setting device 31.

In the switch 32, the dead time setting device 3 is used.
When the signal from 1 is "0", the first-order delay element 27
When the input signal from (1) is "1", the signal of the gain setting device 26 is output as the speed command signal 33 (% SPD). This speed command signal 33 (% SPD) is input to the dead zone setting device 17.

The following effects can be obtained by the above method.

The function of the structure inside the broken line frame in FIG. 1 is called the speed adjustment suppression bias function. Fig. 3 shows the effect of the speed adjustment suppression bias function when the system frequency increases, and Fig. 4 shows the effect of the speed adjustment suppression bias function when the system frequency decreases, from the top, respectively. The ratio will be shown.

When the frequency is increased, the effect as shown in FIG. 3 is obtained. When the system frequency increases, the governor control system changes the fuel amount command value to the gas turbine to a decrease signal, and this decrease signal operates at the change rate preset in the change rate setting unit 13. By this operation, the change in the fuel amount command value is delayed with respect to the target load, and the time difference from the change in the supply amount of combustion air is shortened. As a result, the premixed fuel-air ratio is
It can be changed within the stable operation range of the low NOx combustor shown in the lower part of FIG.

When the frequency drops, the effect as shown in FIG. 4 is obtained. When the system frequency drops, the fuel amount command value to the gas turbine becomes an increase signal in the governor control system, and this increase signal operates at the change rate preset in the change rate setting unit 13. By this operation, the change in the fuel amount command value is delayed with respect to the target load, and the time difference from the change in the supply amount of combustion air is shortened. As a result, the premixed fuel-air ratio is
It can be changed within the stable operation range of the low NOx combustor shown in the lower part of FIG.

In the above process of operation, as shown in the middle part of FIGS. 3 and 4, a slight deviation occurs with respect to the target load. For example, the target multi-axis combined power generation In the case of equipment, by distributing the load deviation to a plurality of gas turbines, the load deviation of the entire power generation equipment can be suppressed.

Next, the effect of the fluctuation suppressing filter means will be described with reference to FIG. Usually, as shown in the upper diagram of FIG. 5, the input value of the system frequency signal 3 includes a small fluctuation component in addition to a large swell component of the system frequency. When the signal containing the minute fluctuation component is used as it is and used as the speed adjustment bias signal, the power generation equipment by the minute component, especially the opening signal of the fuel amount control valve of the gas turbine, the combustion air amount adjusting means, etc. Since the minute operation component is also added to the control operation end operation signal, the movable parts such as the fuel amount control valve and the combustion air amount adjusting means operate frequently with a small amount, and the remaining life consumption rate increases. Therefore, the fluctuation suppressing filter means filters the input system frequency fluctuation signal so as to obtain the waveform shown in the lower side of FIG. By this filtering, it is possible to suppress the control operation end operation signal from instructing a minute operation, and it is possible to reduce the remaining life consumption rate of the movable portion.

According to this embodiment, the MWD signal 2 (MW) of the output command value from the central power feeding command station is converted into the system frequency signal 3
Is corrected and the rate of change of the system frequency used for correction is suppressed, the time difference between the change in the fuel amount and the change in the combustion air amount is reduced, and the fuel is changed according to the MWD signal 2 and the change in the system frequency. Even in the process of changing the amount, it becomes possible to maintain the fuel-air ratio within the stable operating range of the low NOx combustor. Further, since the minute fluctuation component of the system frequency signal used for the correction is removed, the fine movement of the moving parts of the fuel amount adjusting valve of the gas turbine and the combustion air amount adjusting means is reduced, and the life of these devices is extended. There is an effect.

In the above embodiment, for example, when the speed adjustment suppression bias operates during the load changing operation of the plant, the load changes discontinuously due to the operation of the dead zone setting device 17 in FIG. For this purpose, the set value of the dead zone setter 17 is continuously set to a slope value (bias change rate) that does not exceed the speed regulation rate instructed in advance to the target plant. By setting the setting value of the dead zone setting device 17 to the value as described above, it is possible to prevent the load from fluctuating discontinuously, and there is an effect of realizing a smooth load following property.

[0032]

As described above, according to the present invention, in the fuel amount control corresponding to the frequency fluctuation, the sensitivity of speed adjustment is adjusted so that the dynamic fuel-air ratio of the low N0x combustor satisfies the allowable value. Since the control is performed with a drop in the frequency, it becomes possible to follow up so as not to impair the operating performance of the power generation equipment when the frequency fluctuates due to a system accident or the like, which contributes to system stabilization.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the contents of a fluctuation suppression filter means 16 shown in FIG.

FIG. 3 is a conceptual diagram showing the effect of the speed adjustment suppression bias means when the system frequency rises in the embodiment shown in FIG.

FIG. 4 is a conceptual diagram showing the effect of the speed adjustment suppression bias means when the system frequency drops in the embodiment shown in FIG.

5 is a conceptual diagram showing the effect of the fluctuation suppression filter means in the embodiment shown in FIG.

[Explanation of symbols] 1 Actual MW signal (MW) 2 MWD signal (MW) 3 frequency signals 4 First subtractor 5 analog memory 6 First gain setting device 7 Second subtractor 8 Third gain setting device 9 adder 10 constant setting device, 11 Low value selector 12 adder 13 Change rate setting device 14 Suppression rate setting device 15 Primary delay element 16 Fluctuation suppression filter means 17 Dead band setting device 18 Change rate setting device 19 Second gain setting device 20 Third Subtractor 21 Constant setting device 22 Load limiter control signal 23 Exhaust temperature control signal 24 Governor control command signal 25 rpm signal (rpm) 26 Gain setter 27 Primary delay element 28 Subtractor 29 Absolute value calculator 30 comparator 31 Dead time setting device 32 switch 33 Speed command signal (% SPD)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichi Nagai             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd., Thermal Power & Hydro Power Division (72) Inventor Isao Takehara             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd., Thermal Power & Hydro Power Division (72) Inventor Y. Yanaka             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd., Thermal Power & Hydro Power Division (72) Inventor Takeshi Ishida             5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture             Inside the Hitachi information control system control (72) Inventor Masahiko Kimura             3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture             Kansai Electric Power Co., Inc. (72) Inventor Hiroshi Fujiwara             3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture             Kansai Electric Power Co., Inc.

Claims (7)

[Claims] 1. A fuel amount command signal is adjusted so that a deviation between a power generation amount command signal of a gas turbine power generation facility and an actual power generation amount signal of the power generation facility is adjusted to 0, and the power generation amount is input by inputting a system frequency signal. In a governor-free control method for a gas turbine power generation facility that adjusts a command signal, a rate of change of the input system frequency signal is limited, and the power generation amount command signal is adjusted by the signal having the limited rate of change. Governor-free control method for gas turbine power generation equipment. 2. The governor-free control method for gas turbine power generation equipment according to claim 1, further comprising a step of removing small fluctuations of a cycle equal to or shorter than a desired cycle included in the input system frequency signal. Governor-free control method for gas turbine power generation equipment characterized by the above. 3. The governor-free control method for gas turbine power generation equipment according to claim 1, wherein the input system frequency signal passes through a first-order lag element for which a dead time is set, and then the power generation amount command is issued. A governor-free control method for gas turbine power generation equipment, which is used for signal adjustment. 4. The fuel amount command signal is adjusted so that the deviation between the power generation amount command signal of the gas turbine power generation facility and the actual power generation amount signal of the power generation facility is adjusted to 0, and the power generation amount is input by inputting a system frequency signal. In a governor-free control device for a gas turbine power generation facility that adjusts a command signal, a rate adjustment suppression that limits the rate of change of the input system frequency signal and adjusts the power generation command signal by the signal with the rate of change limited. A control device for gas turbine power generation equipment, characterized in that a bias means is provided. 5. The governor-free control device for gas turbine power generation equipment according to claim 4, wherein a system frequency fluctuation suppression filter means for removing small fluctuations of a cycle equal to or shorter than a desired cycle included in the input system frequency signal. A governor-free control device for a gas turbine power generation facility, which comprises: 6. The governor-free control device for gas turbine power generation equipment according to claim 4 or 5, wherein the speed adjustment suppression bias means passes the inputted system frequency signal after the rate of change is limited. A governor-free control device for gas turbine power generation equipment, comprising a first-order lag element with a dead time set. 7. The governor-free control device for gas turbine power generation equipment according to claim 4, wherein the speed adjustment suppressing bias means is formed by including a dead zone setting device having a system frequency as an argument. Is a governor-free control device for gas turbine power generation equipment, wherein a bias change rate is set so as not to exceed a preset speed regulation rate in the gas turbine power generation equipment.