JP2003172154A - Gas turbine power plant and controller for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect power system frequency hunting for automatically preventing gas turbine combustion from becoming unstable due to the phenomenon. <P>SOLUTION: The gas turbine power plant has a gas turbine 3, a synchronous generator 4 driven by the turbine 3 for supplying an output (p) to a power system 2, and a controller 7. The controller 7 contains control means 12-20 for selectively performing governor control for controlling the amount of fuel f* to be injected into the turbine 3 in response to the revolution (n) of the turbine 3 or load limit control for controlling the amount of fuel f* in response to the output (p), and a hunting detection means 11 for detecting frequency hunting in the system 2. The means 12-20 perform load limit control upon detecting frequency hunting. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a gas turbine power plant. The present invention particularly relates to a gas turbine power plant in which deterioration of combustion stability of a gas turbine due to frequency hunting of a power system to which the gas turbine power plant supplies power is prevented.

[0002]

2. Description of the Related Art A gas turbine power plant that drives a synchronous generator by a gas turbine to generate electric power to supply electric power to a power system is widely used.

In a gas turbine power plant, it is necessary to control the voltage supplied to the power system, the amount of power (that is, the output of the synchronous generator), and the frequency within a certain range. Generally, the voltage supplied to the electric power system is stabilized by the control of the synchronous generator, and the electric energy and frequency are stabilized by the control of the gas turbine.

The control of the amount of electric power supplied to the electric power system and the frequency is performed by controlling the flow rate of fuel injected into the gas turbine. A part of the fuel injected into the gas turbine is used to maintain the amount of electric power, and another part is used to maintain the frequency.

Generally, for the control of the fuel input amount, two types are used in combination: load limit control that determines the fuel input amount based on the generator output, and governor control that determines the fuel input amount based on the rotational speed of the gas turbine. . Since the frequency of the electric power supplied to the electric power system depends on the rotation speed of the gas turbine, the frequency can be controlled by controlling the rotation speed of the gas turbine.

In such a gas turbine power plant, when frequency hunting of the electric power system occurs, the amount of fuel input to the gas turbine repeatedly changes due to the frequency hunting. When the frequency of the power system temporarily increases at a certain point, the gas turbine speed also increases due to the temporary increase. Then, the portion of the fuel supplied to the gas turbine that is used to maintain the rotational speed of the gas turbine is increased, and as a result, the generator output is reduced. Since the generator output needs to be kept constant, the fuel input is also increased in order to increase the generator output.
At this time, when the frequency of the electric power system decreases, control is performed to further increase the fuel injection amount in order to increase the gas turbine rotation speed. As described above, frequency hunting of the electric power system causes a large variation in the amount of fuel input, and further destabilizes the combustion performed in the combustor of the gas turbine. Such instability of the fuel gas imposes a burden on the combustor and is not preferable.

It is desired to provide a technique for avoiding instability of combustion of a gas turbine due to system frequency hunting.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a technique for detecting frequency hunting in a power system and automatically avoiding instability of combustion in a gas turbine.

[0009]

[Means for Solving the Problems] Means for solving the problems will be described below by using the numbers and symbols used in the embodiments of the present invention. These numbers / codes are added to clarify the correspondence between the description in [Claims] and the description in [Embodiment of the Invention].
However, the added numbers / codes should not be used to interpret the technical scope of the invention described in [Claims].

The gas turbine power plant according to the present invention is controlled by a gas turbine (3) and a synchronous generator (4) which is driven by the gas turbine (3) and outputs a generator output (p) to the electric power system (2). A device (7). The control device (7) controls the fuel injection amount (f ^* ) to the gas turbine (3) in response to the gas turbine rotational speed (n) of the gas turbine (3) and the generator output (p). )
Control means (12 to 2) for selectively performing either of the load limit control for controlling the fuel input amount (f ^* ) in response to
0) and hunting detection means (11) for detecting frequency hunting of the power system (2). Control means (12
20 to 20) perform load limit control when frequency hunting is detected.

It is preferable that the control means (12 to 20) limit the increase rate of the fuel injection amount (f ^* ) within a predetermined range when the frequency hunting is detected.

In the gas turbine power plant,
The control means (12 to 20) includes load limit control means (12, 13, 41) for performing load limit control, and the load limit control means (12, 13, 41) includes:
Generator output target value ^{(p *),} the steady-state power generator output target value _{(p ST} ^*) and hunting during the generator output target value _{(p H T}
^* ) And a generator output target value determining means (41) which is defined as one of the above, and a fuel injection amount (f ^* ) so that the generator output (p) becomes the generator output target value (p ^* ). The fuel output calculating means (12, 13) for determining, and the generator output target value determining means (41), when frequency hunting is detected, sets the generator output target value (p ^* ) to the generator output during hunting. It is preferable that the target value (p _HT ^* ) is set and the hunting generator output target value (p _HT ^* ) is smaller than the steady state generator output target value (p _ST ^* ).

In the gas turbine power plant,
The control means (12 to 20) are load limit control means (12, 13, 44, 4) for performing load limit control.
5) and is provided with load limit control means (12, 13, 4).
4, 45) is a change rate limiting means (44, 45) that follows the generator output (p) and generates a change rate limited generator output (p ″) in which the change rate is limited to a predetermined range.
And generator output (p) and rate of change limited generator output (p ")
And a fuel input amount calculating means (45) that determines the fuel input amount (f ^* ) so that the generator output target value (p ^* ) and the selected one match. 1
2, 13), and the selecting means (45) preferably selects the rate-of-change limited generator output (p ″) when frequency hunting is detected.

The hunting detection means (11) preferably monitors both the gas turbine speed (n) and the generator output (p) to detect the occurrence of frequency hunting.

In this case, the hunting detection means (11)
Are gas turbine rotation speed hunting detection means (11a) for detecting gas turbine rotation speed hunting of gas turbine rotation speed (n) and generator output hunting detection means for detecting generator output hunting of generator output (p). (11
b) and frequency hunting detection means (37) for detecting the occurrence of frequency hunting due to the occurrence of both gas turbine speed hunting and generator output hunting.

The gas turbine rotation speed hunting detecting means (11a) follows the gas turbine rotation speed (n), and the change rate limited gas turbine rotation speed (n ') in which the change rate is limited to a predetermined range. Gas turbine speed change rate limiting means (21), and means for detecting gas turbine speed hunting based on the difference between the gas turbine speed (n) and the change rate limiting turbine speed (n ′). (22 to 28) is preferable.

The gas turbine rotation speed hunting detection means (11a) divides the value (n ') corresponding to the moving average of the gas turbine rotation speed (n) in the past predetermined time and the gas turbine rotation speed (n). It is preferable to detect gas turbine speed hunting based on the difference.

Further, the generator output hunting detecting means (1
1b) is a change rate limited generator output (p ') that follows the generator output (p) and has a change rate limited to a predetermined range.
Generator output change rate limiting means (29) for generating
Means (3) for detecting generator output hunting based on the difference between the generator output (p) and the rate-of-change limited generator output (p ')
0 to 36) are preferably included.

Further, the generator output hunting detecting means (1
1b) is capable of detecting the generator output hunting based on the difference between the generator output (p) and a value (p ′) corresponding to the moving average of the generator output (p) in the past predetermined time. preferable.

The gas turbine power plant control apparatus according to the present invention is a governor control for controlling the fuel injection amount (f ^* ) to the gas turbine (3) in response to the gas turbine speed (n) of the gas turbine (3). And a gas turbine (3)
Generator output (p) of the synchronous generator (4) driven by
Control means (12 to 2) for selectively performing either of the load limit control for controlling the fuel input amount (f ^* ) in response to
0) and hunting detection means (11) for detecting frequency hunting of the power system (2) to which the generator output (p) is supplied from the synchronous generator (4). The control means (12 to 20) performs load limit control when frequency hunting is detected.

The power system frequency hunting detection device according to the present invention comprises a gas turbine rotational speed (n) of a gas turbine (3) and a generator output (p) of a synchronous generator (4) driven by the gas turbine (3). ), And a generator output (p) is supplied from the synchronous generator (4) based on the gas turbine speed (n) and the generator output (p). A frequency hunting detection means (11) for detecting the occurrence of frequency hunting in the power system (2) is provided.

In the method for controlling a gas turbine power plant according to the present invention, (a) the fuel injection amount (f ^* ) to the gas turbine (3) is controlled in response to the gas turbine speed (n) of the gas turbine (3). Governor control to control or load limit control to control fuel injection amount (f ^* ) in response to generator output (p) of synchronous generator (4) driven by gas turbine (3) Steps to perform,
(B) detecting frequency hunting in the power system (2) to which the generator output (p) is supplied from the synchronous generator (4). Step (a) includes (c) switching from governor control to load limit control when frequency hunting is detected.

The program according to the present invention includes: (a) governor control for controlling a fuel injection amount (f ^* ) to the gas turbine (3) in response to the gas turbine rotational speed (n) of the gas turbine (3), Selectively performing one of load limit control for controlling a fuel injection amount (f ^* ) in response to a generator output (p) of a synchronous generator (4) driven by a gas turbine (3); , (B) detecting frequency hunting of the power system (2) to which the generator output (p) is supplied from the synchronous generator (4), and (a) step, (c) frequency hunting is detected. And a program for executing a method including a step of switching from governor control to load limit control by a computer.

The power system frequency hunting detection method according to the present invention comprises: (d) the gas turbine speed (n) of the gas turbine (3) and the generator of the synchronous generator (4) driven by the gas turbine (3). The generator output (p) is supplied from the synchronous generator (4) based on the step of monitoring the output (p) and (e) the gas turbine speed (n) and the generator output (p). Detecting the occurrence of frequency hunting in the power system (2).

The program according to the present invention comprises (d) the gas turbine speed (n) of the gas turbine (3) and the generator output (p) of the synchronous generator (4) driven by the gas turbine (3). And (e) the power system (2) supplied with the generator output (p) from the synchronous generator (4) based on the gas turbine speed (n) and the generator output (p). And a step of detecting the occurrence of frequency hunting, which is executed by a computer.

[0026]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
An embodiment of a gas turbine power plant according to the present invention will be described.

(First Embodiment) FIG. 1 shows an embodiment of a gas turbine power plant according to the present invention. The gas turbine power plant 1 is provided with a gas turbine 3 together with a synchronous generator 4. The gas turbine 3 drives the synchronous generator 4. The synchronous generator 4 generates electric power and supplies it to the electric power system 2. The gas turbine 1 is connected with a rotation speed measuring device 5 for measuring a turbine rotation speed n, and the synchronous generator 4 has an amount of electric power supplied to the electric power system 2, that is, a generator output p of the synchronous generator 4. A power meter 6 for measuring is connected.

The flow rate (fuel input amount) of the fuel supplied to the combustor 3a of the gas turbine 3 is controlled by the controller 7. The control device 7 is a computer. Control device 7
Exclusively performs the governor control that controls the fuel input amount in response to the turbine speed n and the load limit control that controls the fuel input amount in response to the generator output p. The control device 7 is supplied with a control signal S _C for instructing whether to perform governor control or load limit control.
Performs either governor control or load limit control according to the control signal S _C. The control device 7 determines the fuel input amount command value f ^* (hereinafter, referred to as “fuel input amount command value f ^* ”) by either the governor control or the load limit control. In the combustor 3a of the gas turbine 3,
The fuel is supplied at the flow rate designated by the fuel injection amount command value f ^* . The fuel injection amount command value f ^* is expressed in percent (%). 0% corresponds to the fuel input amount being 0, and 100% corresponds to the fuel input amount corresponding to the maximum rated output.

Further, the control device 7 detects the occurrence of frequency hunting of the power system 2 (hereinafter referred to as "system frequency hunting"). The system frequency hunting is detected based on the turbine speed n and the generator output p. The controller 7 controls the turbine speed n and the generator output p.
Is monitored to detect the occurrence of system frequency hunting in the power system 2.

When the control device 7 detects that system frequency hunting has occurred, the control device 7 compulsorily switches the control of the fuel injection amount to the load limit control regardless of the instruction of the control signal S _C. When system frequency hunting occurs, the turbine speed n fluctuates due to the fluctuation of the frequency of the power system 2. Therefore, when the governor control based on the turbine rotation speed n is performed, the fuel injection amount command value f ^* also changes with the change of the frequency, and the combustor 3a of the gas turbine 3 changes.
Load on. The load limit control based on the generator output p is less affected by the system frequency hunting than the governor control. Therefore, by forcibly switching to the load limit control, the fluctuation of the fuel injection amount command value f ^* is suppressed, and the combustor 3 caused by the system frequency hunting is suppressed.
The load on a can be suppressed.

FIG. 2 is a functional block diagram showing in detail the operation of the control device 7 described above. The control device 7 is equivalent to the hunting detector 11 and the subtractor 1
2, PI controller 13, target value converter 14, subtractor 15,
It includes a P controller 16, an LD / GV switch 17, an LD 5% adder 18, a GV 5% adder 19, and a low value selector 20. Hunting detector 11, subtractor 12, PI controller 13, target value converter 14, subtractor 15, P controller 16, LD / G
V switching device 17, LD 5% adder 18, GV 5% adder 1
9. The function of the low value selector 20 is actually realized by the control device 7 executing a computer program.

Command value f _LD ^* of the fuel input amount based on the load limit control (hereinafter, "LD fuel input amount command value f
_LD ^* ”. ) Is calculated by the subtractor 12 and the PI controller 13. The subtractor 12 uses the generator output target value p ^*
The generator output p is subtracted from this to calculate the deviation p ^* -p. P
The I controller 13 performs proportional-plus-integral control (PI control) based on the deviation p ^* -p, and sets the LD fuel injection amount command value f _LD ^* so that the generator output p becomes the generator output target value p ^*. calculate. LD fuel input amount command value f _LD ^* is 0% to 100
Takes a value between%.

On the other hand, the command value f _GV ^* of the fuel injection amount based on the governor control (hereinafter referred to as “GV fuel injection amount command value f _GV
^* ”. ) Is the target value converter 14, the subtractor 15, P
It is calculated by the controller 16. The target value converter 14 converts the generator output target value p ^* into the turbine rotation speed target value n ^* . The subtractor 15 subtracts the turbine speed n from the turbine speed target value n ^* to calculate a deviation n ^* -n. The P controller 16 performs proportional control (P control) based on the deviation p ^* -p, and calculates the GV fuel injection amount command value f _GV ^* so that the turbine speed n approaches the turbine speed target value n ^*. To do. The GV fuel input command value f _GV ^* is 0% to 10
It takes a value between 0%.

The conversion formula from the generator output target value p ^* to the turbine speed target value n ^* , the proportional gain and the integral gain of the PI controller 13, and the gain of the P controller 16 are the LD fuel injection amount in the steady state. The command value f _LD ^* and the GV fuel input amount command value f _GV ^* are set to be substantially equal.

One of the LD fuel input amount command value f _LD ^* and the GV fuel input amount command value f _GV ^* is used to generate the fuel input amount command value f ^* , whereby load limit control and governor control are performed. And are done exclusively. LD / GV switch 1 is used to switch between load limit control and governor control.
7, LD 5% adders 18, 19 and low value selector 20.

The LD / GV switch 17 is provided outside the control device 7.
Control signal S input from the section_CDepending on the switch signal
S_wThe "High" level or "Low" level
Set it to some extent. The LD / GV switch 17 has a control signal.
S_CSwitches to the governor control
Signal S_wIs set to "High" level, and the control signal S _C
When the load limit control is instructed by
Switch signal S_wIs set to the "Low" level.

The LD 5% adder 18 uses the switch signal S _w
Is at the "High" level, that is, when the execution of the governor control is instructed, the LD fuel input amount command value f _LD ^*
Is added with 5% and output, and the switch signal _Sw is "Lo
When it is at the w "level, that is, when execution of the load limit control is instructed, the LD fuel input amount command value f _LD ^* is output as it is.

The GV5% adder 19 uses the switch signal S _w.
Is at the "High" level, that is, when the execution of the governor control is instructed, the GV fuel input amount command value f _GV ^*
Is output as it is, and when the switch signal _Sw is at the “Low” level, that is, when execution of the load limit control is instructed, 5% is added to the GV fuel input amount command value f _GV ^* and output. LD fuel injection amount command value f _LD ^* and GV
The addition of 5% to the fuel input amount command value f _{G V} ^* is performed exclusively.

The low value selector 20 outputs the smaller one of the outputs of the LD 5% adder 18 and the GV 5% adder 19 as the fuel injection amount command value f ^* . As described above, in the steady state, the LD fuel input amount command value f _LD ^* and the GV fuel input amount command value f _GV ^* are substantially equal to each other. Therefore, in the steady state, the LD fuel input amount command value f _{Of the LD} ^* and the GV fuel input amount command value f _GV ^* , the one to which 5% is not added is output as the fuel input amount command value f ^* . That is,
When the control signal S _C instructs the execution of the governor control while the gas turbine 3 is in a steady operation, the GV fuel input amount command value f _GV ^* is set as the fuel input amount command value f ^*. When it is output and the execution of the load limit control is instructed, the LD fuel input amount command value f _LD ^* is output as the fuel input amount command value f ^* . In this way, the governor control and the load limit control are controlled by the control signal S _C.
Can be switched according to.

However, if system frequency hunting occurs in the power system 2 while the governor control is being performed,
Forced switching to load limit control is performed. The system frequency hunting detection signal S _HT ^f output by the hunting detector 11 is compulsorily switched to the load limit control.
In response to. When detecting the system frequency hunting, the hunting detector 11 notifies the LD / GV switch 17 of the occurrence of the system frequency hunting by the system frequency hunting detection signal S _HT ^f . LD / GV switch 17
Recognizes the occurrence of the system frequency hunting, regardless of the instruction of the control signal S _C, the switch signal S _w "Lo
The LD 5% adder 18 outputs the LD fuel input amount command value f in response to the switch signal S _w .
_LD ^* is output as it is, and the GV 5% adder 19 outputs GV
The fuel input amount command value f _GV ^* is added with 5% and output. Therefore, the low value selector 20 outputs the LD fuel input amount command value f _LD.
^* Is output as the fuel input amount command value f ^* . In this way, compulsory switching to the load limit control is performed.

The occurrence of system frequency hunting is detected by the hunting detector 11 on the basis of the generator output p and the turbine speed n. The hunting detector 11 is
The generator output p and the turbine speed n are monitored to detect system frequency hunting, and a system frequency hunting detection signal S _HT ^f indicating whether or not system frequency hunting has occurred is generated.

When hunting occurs in both the turbine speed n and the generator output p, the hunting detector 11 determines that system frequency hunting has occurred, and sets the system frequency hunting detection signal S _HT ^f to "High". Output level. The turbine speed n follows the frequency of the power system 2 and is an index of system frequency hunting. The fact that the turbine speed n follows the frequency of the power system 2 serves to stabilize the power system 2. Is also playing.
Therefore, the fluctuation of the turbine speed n must be allowed to some extent. Therefore, when hunting occurs in both the generator output p and the turbine speed n, the hunting detector 11 determines that system frequency hunting that requires some countermeasure has occurred.

FIG. 4 is a functional block diagram showing the operation of the hunting detector 11. The hunting detector 11 equivalently includes a turbine speed hunting detector 11a and a generator output hunting detector 11b. The turbine speed hunting detector 11a detects hunting at the turbine speed n, and the generator output hunting detector 11b detects hunting at the generator output p.

Turbine speed hunting detector 11a
Are equivalently, the change rate limiter 21 and the deviation calculator 2
2, a deviation upper limit detector 23, an off delay 24, a deviation lower limit detector 25, an off delay 26, an AND gate 27, and an on delay 28.

The change rate limiter 21 outputs a turbine rotation speed fluctuation reference value n'which tracks (follows) the turbine rotation speed n while limiting the change rate within a predetermined range. The turbine rotation speed fluctuation reference value n ′ is a value corresponding to a moving average that is an average of the turbine rotation speeds n in a predetermined time in the past.

The deviation calculator 22 subtracts the turbine speed fluctuation reference value n ′ from the turbine speed n to obtain a deviation nn ′.
To calculate. When the hunting of the turbine speed n hunts and the turbine speed n fluctuates rapidly, the deviation n-
The absolute value of n'becomes large. The deviation n−n ′ is supplied to the deviation upper limit detector 23 and the deviation lower limit detector 25.

The deviation upper limit detector 23, when the difference n-n 'becomes increased predetermined upper limit _n ^U _n (> 0), and outputs the upper limit value trigger pulse _T ^{U n} is a rectangular pulse. Off delay 24 receives the upper limit value trigger pulse _T ^{U n,} the received time after, by a predetermined time _{T D1} "Hi
gh "level is output.

The deviation upper limit detector 25 outputs a lower limit value trigger pulse T _L ⁿ which is a rectangular pulse when the deviation n−n ′ decreases to a predetermined lower limit value n _L ⁿ (<0). .
When the off-delay 26 receives the lower limit value trigger pulse T _L ⁿ , the off-delay 26 is “H” for a predetermined time T _D1 after the received time.
The "high" level is output.

The AND gate 27 calculates and outputs a logical product (AND) of the output of the off-delay 24 and the output of the off-delay 26.

In the on-delay 28, after the output of the AND gate 27 is raised to the "High" level and a predetermined time has elapsed, the output of the AND gate 27 becomes "High".
While being maintained at the "h" level, it outputs the "High" level. When the output of the AND gate 27 becomes the "Low" level, the output of the on-delay 28 also returns to the "Low" level. , Turbine speed n
Is a turbine speed hunting detection signal S _HT ⁿ indicating the presence or absence of hunting. The fact that the turbine speed hunting detection signal S _HT ⁿ is at the “High” level indicates that hunting at the turbine speed n has occurred.

Referring to FIG. 4, when the turbine speed n is increased,
When the ching occurs, the turbine speed n changes rapidly.
However, it has a value equivalent to the moving average of the turbine speed n.
The fluctuation of the turbine speed fluctuation reference value n '
It is smaller than the variation of the number n. Therefore, the turbine speed n
Hunting refers to turbine speed n and turbine speed fluctuation
It appears in the deviation n−n ′ from the reference value n ′. Deviation n-n '
Large absolute value means hunting at turbine speed n
The occurrence of The deviation n−n ′ is the upper limit value n _U ⁿThan
Also becomes larger, the output S of the off-delay 24_U ^pIs
After time T_D1Only goes to "High" level. Deviation n
-N 'is the upper limit value n_L ⁿBecomes smaller than the off delay
-26 output S_U ⁿIs the time T_D1Only "Hig
H ”level. Hunting at turbine speed n continues.
If it continues, the output S of the off-delay 24_U ^pAnd off
Output S of delay 26_U ⁿIs the "High" level
Keep going.

[0052] At this time, a temporary change of turbine speed n in order not to erroneously detect a hunting of the turbine speed n, and outputs S _U ^p off delay 24, the output S _U ⁿ of the off-delay 26 Both are "Hi" for the time T _D2
"when it is maintained at a level, turbine speed hunting detection signal _{S HT} ⁿ is" gh becomes High "level,
The turbine speed hunting detection signal S _HT ⁿ is in a state indicating that hunting of the turbine speed ⁿ is generated.

On the other hand, the generator output hunting detector 11b for detecting the hunting of the generator output p is equivalently equivalent to the change rate limiter 29, the deviation calculator 30, the deviation upper limit detector 31, the off delay 32, and the deviation lower limit. Detector 33, OFF delay 34, AND gate 35, and ON delay 36
including. The configuration of the generator output hunting detector 11b is
It has the same configuration as the turbine rotation speed hunting detector 11a and performs the same operation, except that the generator output p is input instead of the turbine rotation speed n. When the hunting of the generator output p occurs, the generator output hunting detection signal S _HT ^p becomes the “High” level.

The AND gate 37 is a turbine speed
Ching detection signal S_HT ⁿAnd generator output hunting detection signal
Issue S_HT ^pAnd the logical product of
Issue S _HT ^fOutput as. That is, the turbine speed n
When hunting occurs on both the generator output p and the system,
General frequency hunting detection signal S_HT ^fIs "High"
It becomes a bell and shows the occurrence of system frequency hunting
Become. As already mentioned, system frequency hunting
Occurrence is detected and system frequency hunting detection signal S_HT
^fIs set to "High" level, load limit control
To the LD fuel input amount command value f
_LD ^*Is the fuel input command value f^*Is output as. Immediately
Then, compulsory switching to the load limit control is performed.

As explained above, the first implementation
In the mode, when the occurrence of system frequency hunting is detected by the hunting detector 11, forced switching to the load limit control is performed. This suppresses fluctuations in the amount of fuel input to the combustor 3a due to system frequency hunting. At this time, the hunting detector 11 recognizes that system frequency hunting has occurred when hunting has occurred in both the turbine speed n and the generator output p. As a result, fluctuations in the amount of fuel input are suppressed when it becomes truly necessary to protect the combustor 3a.

(Second Embodiment) In the second embodiment,
When the system frequency hunting occurs, the load limit control is compulsorily switched and the fuel injection amount command value f ^* is decreased, whereby the combustor 3a is further protected. The fuel input amount command value f ^* is decreased by decreasing the generator output target value p ^* . In the load limit control, the fuel injection amount command value f ^* is controlled so that the generator output p matches the generator output target value p ^*. Therefore, the decrease in the generator output target value p ^* reduces the fuel injection amount command. The value f ^* can be reduced.

FIG. 5 is a functional block diagram showing the operation of the control device 7 in the second embodiment. In the second embodiment, a switch 41 having the following functions is equivalently added to the control device 7 of the first embodiment. The function of the switch 41 is actually realized by a computer program.

The switch 41 is responsive to the system frequency hunting detection signal S _HT ^{f described} above and is one of the hunting generator output target value p _HT ^* and the steady state generator output target value p _ST ^*. Is output as the generator output target value p ^* . The hunting generator output target value p _HT ^* is smaller than the steady-state generator output target value p _ST ^* . The hunting generator output target value p _HT ^* is set so that stable combustion of the combustor 3 a of the gas turbine 3 is expected. The switching device 41 uses the system frequency hunting detection signal S
When _{H T} ^f is in the "Low" level, the steady-state power generator output target value _{p ST} ^* output as the generator output target value ^{p *,} the system frequency hunting detection signal _{S HT} ^f is "Hig
At the h "level, the hunting generator output target value p _HT ^* is output as the generator output target value p ^* .

System frequency hunting occurs in power system 2
If not, system frequency hunting detection signal S_HT
^fIs the "Low" level, so the generator output target
Value p ^*Is the steady state generator output target value p_ST ^*become. This
, The control signal S_CGovernor control and load in response to
Limit control can be switched.

When system frequency hunting occurs in the power system 2, the system frequency hunting detection signal S _HT ^f becomes "H".
Then, the load limit control is compulsorily switched to the "high" level, which suppresses the fluctuation of the fuel to the combustor 3a due to the system frequency hunting.
The generator output target value p ^* is the steady-state generator output target value p _{S T}
^* Hunting generator output target value p _HT less than ^*
Therefore, the fuel injection amount command value f ^* is reduced. As a result, the amount of fuel input to the combustor 3a is suppressed, and the combustor 3a is protected from system frequency hunting.

As described above, in the second embodiment, the load limit control is forcibly switched and the amount of fuel input to the combustor 3a is suppressed, and the protection of the combustor 3a of the gas turbine 3 is strengthened. To be done.

(Third Embodiment) In the third embodiment,
When system frequency hunting occurs, the load limit control is compulsorily switched, and the rate of increase of the fuel injection amount command value f ^* is limited, whereby the combustor 3a is controlled.
Further protection of the.

FIG. 6 is a functional block diagram showing the operation of the control device 7 in the third embodiment. In the third embodiment, a change rate limiter 42 and a switch 43 having the following functions are equivalently added to the control device 7 of the first embodiment. Change rate limiter 42
The functions of the switch 43 and the switch 43 are actually realized by a computer program.

The change rate limiter 42 includes the low value selector 2
The fuel injection amount command value f ^* output by 0 is input. The change rate limiter 42 tracks the fuel injection amount command value f ^* while limiting the change rate to a predetermined range, and outputs the change rate limited fuel injection amount command value f ^* '.

The switch 43 responds to the system frequency hunting detection signal S _HT ^f by selecting one of the fuel input amount command value f ^* and the change rate limited fuel input amount command value f ^* ′ as a low value selector. Output to 20. System frequency hunting has not occurred and system frequency hunting detection signal _SHT ^f is "
At the "Low" level, the switch 43 outputs the fuel injection amount command value f ^* to the low value selector 20. On the other hand, system frequency hunting occurs and the system frequency hunting detection signal _SHT ^f is "High". Switcher 4 when level
3 outputs the change rate limited fuel input amount command value f ^* 'to the low value selector 20.

The low value selector 20 is the LD 5% adder 18,
The lowest output of the GV5% adder 19 and the switch 43 is output as the fuel input amount command value f ^* .

When system frequency hunting does not occur, the switch 43 outputs the fuel input amount command value f ^* to the low value selector 20, so that the fuel input amount command value f ^* is the LD fuel input amount command. Value f _LD ^* and GV fuel input command value f _GV
Matches the smaller of ^* and. Therefore, the change rate limiter 42 and the switch 43 have substantially no effect. That is, when system frequency hunting does not occur, the control device 7 performs the same operation as in the first embodiment.

On the other hand, system frequency hunting occurs.
And because the load limit control can be switched to,
Charge input command value f_LD ^*Is as it is, GV fuel input finger
Command value f _GV ^*Is added to 5% and supplied to the low value selector 20.
To be done. Therefore, the GV fuel input amount command value f_GVIs
Fuel input command value f^*Is not used to generate

Further, the low value selector 20 has a change rate control.
Change rate limited fuel input amount command value f generated by limiter 42
^*′ Is supplied, whereby the fuel input amount command value f^*of
The rate of increase is limited to a certain range. LD fuel input finger
Command value f_LD ^*Change rate limiting fuel when
Input amount f^*'Reduction rate is limited to a certain range
Therefore, the LD fuel input amount command value f_LD ^*Change rate limit
Fuel input command value f^*Is smaller than ‘ Therefore, L
D Fuel input amount command value f_LD ^*Is the fuel input command value f^*When
And output. On the other hand, LD fuel input amount command value f_LD ^*
Change rate limit fuel input command value
f^*′ Is limited to a certain range, the change rate
Limit fuel input command value f^*’Is the LD fuel input command
Value f_LD ^*Will be smaller than. Therefore, change rate limit
Fuel input command value f^*’Is the fuel injection amount command value f^*As
Is output. Change rate limited fuel injection amount command value f^*'of
Since the rate of increase is limited to a certain range, the fuel input
Value f^*The rate of increase of is also limited to a certain range.

As described above, in the third embodiment, when the system frequency hunting occurs, the fuel injection amount command value f ^*.
Is limited to a certain range, thereby further protecting the combustor 3a.

(Fourth Embodiment) In the fourth embodiment,
When system frequency hunting occurs, the load limit control is forcibly switched, and the load limit control algorithm is changed so that the fluctuation of the fuel injection amount command value f ^* becomes gentle. Bowl 3
Further protection of a is intended.

FIG. 7 is a function block diagram showing the operation of the control device 7 in the fourth embodiment. In the fourth embodiment, a change rate limiter 44 and a switch 45 having the following functions are equivalently added to the control device 7 of the first embodiment. Change rate limiter 44
The functions of the switch 45 and the switch 45 are actually realized by a computer program.

The change rate limiter 44 outputs a change rate limited generator output p "for tracking the generator output p while limiting the change rate within a predetermined range. Change of the change rate limited generator output p" Since the rate is limited to a predetermined range, the rate of change of the rate-of-change limited generator output p ″ becomes gentler than the generator output p even if the generator output p hunts.

The switch 45 outputs one of the generator output p and the rate-of-change limited generator output p ″ to the subtractor 12 in response to the system frequency hunting detection signal S _HT ^f .
When the system frequency hunting has not occurred and the system frequency hunting detection signal S _HT ^f is at the “Low” level, the switching unit 45 outputs the generator output p to the subtractor 12. When the system frequency hunting occurs and the system frequency hunting detection signal S _HT ^f is at the “High” level, the switching unit 45 outputs the change rate limited generator output p ″ to the subtracter 1
Output to 2.

When the system frequency hunting does not occur, the generator output p is output to the subtractor 12 and the controller 7
Performs the same operation as in the first embodiment.

On the other hand, when system frequency hunting occurs, the load limit control is switched to, and the LD fuel input amount command value f _LD ^* is output from the low value selector 20 as the fuel input amount command value f ^* . At this time, the switch 45 outputs the rate-of-change limited generator output p ″ to the subtractor 12, so that L
The D fuel injection amount command value f _LD ^* is the generator output target value p ^*
The deviation p ^* -p "between the change rate limited generator output p" and the change rate limited generator output p "is calculated to be small. Since the change rate limiter generator rate of change of the output p "is limited to a predetermined range, fluctuation of LD charged fuel amount command value f _LD ^* by system frequency hunting is suppressed. Therefore, the fuel input amount command value f ^* Is also suppressed.

As described above, in the fourth embodiment, when the system frequency hunting occurs, the load limit control is forcibly switched to the LD fuel input amount command value f _LD ^*.
Is output as the fuel input amount command value f ^* . At the same time, L
The change in the fuel input amount command value f ^* is suppressed by calculating the D fuel input amount command value f _LD ^* based on the change rate limited generator output p ″ in which the change rate is limited. Further protection of the combustor 3a is achieved.

[0078]

The present invention provides a technique for detecting frequency hunting in a power system and automatically avoiding instability of combustion in a gas turbine.

[Brief description of drawings]

FIG. 1 shows a gas turbine power plant according to an embodiment of the present invention.

FIG. 2 is a function block diagram showing an operation of the control device 7 in the first embodiment.

FIG. 3 is a functional block diagram showing an operation of the hunting detector 11.

FIG. 4 is a timing chart showing the operation of the hunting detector 11.

FIG. 5 is a function block diagram showing an operation of the control device 7 in the second embodiment.

FIG. 6 is a functional block diagram showing an operation of the control device 7 in the third embodiment.

FIG. 7 is a functional block diagram showing an operation of the control device 7 in the fourth embodiment.

[Explanation of symbols]

1: Gas turbine power plant 2: Power system 3: Gas turbine 3a: Combustor 4: Synchronous generator 5: Rotation speed measuring instrument 6: Power meter 7: Control device 11: Hunting detector 11a: Turbine speed hunting detector 11b: Generator output hunting detector 12: Subtractor 13: PI controller 14: Target value converter 15: Subtractor 16: P controller 17: LD / GV switch 18: LD 5% adder 19: GV 5% adder 20: Low value selector 21: Change rate limiter 22: Deviation calculator 23: Deviation upper limit detector 24: Off delay 25: Deviation lower limit detector 26: Off delay 27: AND gate 28: On delay 29: Change rate limiter 30: Deviation calculator 31: Deviation upper limit detector 32: Off delay 33: Lower limit deviation detector 34: Off delay 35: AND gate 36: On delay 37: AND gate 41: Switching device 42: Change rate limiter 43: Switching device 44: Change rate limiter 45: Switching device

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H590 AA11 AA13 AA30 BB02 CA08                       CC01 CE01 DD23 DD64 EB02                       EB14 EB21 FA01 FA05 FA08                       FC11 GA02 GA06 GA09 HA02                       HA06 HA09 HA27 HB04 JA12                       JA13

Claims (16)

[Claims] 1. A gas turbine, a synchronous generator driven by the gas turbine to output a generator output to an electric power system, and a controller, wherein the controller adjusts the gas turbine speed of the gas turbine. In response, a governor control for controlling the amount of fuel input to the gas turbine,
A control unit that selectively performs any one of load limit control that controls the fuel input amount in response to the generator output; and a hunting detection unit that detects frequency hunting of the electric power system. Is a gas turbine power plant that performs the load limit control when the frequency hunting is detected. 2. The gas turbine power plant according to claim 1, wherein the control unit limits an increase rate of the fuel input amount within a predetermined range when the frequency hunting is detected. . 3. The gas turbine power plant according to claim 1, wherein the control unit includes a load limit control unit for performing the load limit control, and the load limit control unit sets a generator output target value. A generator output target value determining means defined in any one of a steady-state generator output target value and a hunting generator output target value; and the fuel so that the generator output becomes the generator output target value. Including a fuel input amount calculating means for determining the input amount, the generator output target value determination means, when the frequency hunting is detected, the generator output target value is set to the hunting generator output target value, A gas turbine power plant in which the hunting generator output target value is smaller than the steady-state generator output target value. 4. The gas turbine power plant according to claim 1, wherein the control unit includes a load limit control unit for performing the load limit control, and the load limit control unit follows the generator output. And a change rate limiting means for generating a change rate limited generator output with a change rate limited to a predetermined range, and a selection for selecting one of the generator output and the change rate limited generator output. And a fuel input amount calculation unit that determines the fuel input amount so that the generator output target value and the one match with each other, and the selection unit, when the frequency hunting is detected, the change rate limit. A gas turbine power plant that selects a generator output as one of the above. 5. The gas turbine power plant according to claim 1, wherein the hunting detection means monitors both the gas turbine rotation speed and the generator output to detect the occurrence of the frequency hunting. Power plant. 6. The gas turbine power plant according to claim 5, wherein the hunting detection means includes a gas turbine rotation speed hunting detection means for detecting gas turbine rotation speed hunting of the gas turbine rotation speed, and the generator output. Generator output hunting detecting means for detecting generator output hunting, and frequency hunting detecting means for detecting occurrence of the frequency hunting due to occurrence of both the gas turbine rotational speed hunting and the generator output hunting. Gas turbine power plant. 7. The gas turbine power plant according to claim 6, wherein the gas turbine rotation speed hunting detection unit follows the gas turbine rotation speed, and the change rate is limited to a predetermined range. A gas turbine rotational speed change rate limiting means for generating a limited gas turbine rotational speed; and means for detecting the gas turbine rotational speed hunting based on a difference between the gas turbine rotational speed and the change rate limited gas turbine rotational speed. Including gas turbine power plant. 8. The gas turbine power plant according to claim 6, wherein the gas turbine rotation speed hunting detection means has a value corresponding to a moving average of the gas turbine rotation speed in a past predetermined time, and the gas turbine. A gas turbine power plant that detects the gas turbine rotation speed hunting based on a difference from the rotation speed. 9. The gas turbine power plant according to claim 6, wherein the generator output hunting detection unit follows the generator output and the change rate limited power generation in which the change rate is limited to a predetermined range. A gas turbine power plant comprising: a generator output change rate limiting means for generating a generator output; and a means for detecting the generator output hunting based on a difference between the generator output and the change rate limited generator output. 10. The gas turbine power plant according to claim 6, wherein the generator output hunting detection means has a value corresponding to a moving average of the generator output in a past predetermined time, and the generator output. A gas turbine power plant that detects the generator output hunting based on the difference between 11. A governor control for controlling an amount of fuel input to the gas turbine in response to a gas turbine rotation speed of the gas turbine, and a generator output of a synchronous generator driven by the gas turbine in response to the generator output. And a hunting detection means for detecting a frequency hunting of a power system to which the generator output is supplied from the synchronous generator. The control means is a gas turbine power plant control device that performs the load limit control when the frequency hunting is detected. 12. A monitoring means for monitoring a gas turbine rotation speed of a gas turbine and a generator output of a synchronous generator driven by the gas turbine, and based on the gas turbine rotation speed and the generator output. , A frequency hunting detection device for detecting the occurrence of frequency hunting in a power system supplied with the generator output from the synchronous generator. 13. (a) Response to a governor control for controlling the amount of fuel input to the gas turbine in response to the gas turbine speed of the gas turbine, and to a generator output of a synchronous generator driven by the gas turbine. And selectively performing any one of load limit control for controlling the fuel input amount, and (b) detecting frequency hunting of the power system to which the generator output is supplied from the synchronous generator. The step (a) further comprises: (c) switching the governor control to the load limit control when the frequency hunting is detected. 14. (a) Responsive to a governor control for controlling an amount of fuel input to the gas turbine in response to a gas turbine rotation speed of the gas turbine, and a generator output of a synchronous generator driven by the gas turbine. And selectively performing any one of load limit control for controlling the fuel input amount, and (b) detecting frequency hunting of the power system to which the generator output is supplied from the synchronous generator. A program for executing a method by a computer, which comprises the step (a), including the step (c) of switching from the governor control to the load limit control when the frequency hunting is detected. 15. (d) monitoring the gas turbine speed of the gas turbine and the generator output of a synchronous generator driven by the gas turbine; (e) the gas turbine speed and the generator. And detecting the occurrence of frequency hunting in the power system supplied with the generator output from the synchronous generator based on the output. 16. (d) monitoring the gas turbine speed of the gas turbine and the generator output of a synchronous generator driven by the gas turbine; (e) the gas turbine speed and the generator. And a step of detecting the occurrence of frequency hunting in a power system supplied with the generator output from the synchronous generator based on the output.