JP2003148170A - Method for controlling load of power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain thermal stress and instable behaviors generated to a power plant due to variation of system frequency, and also to stabilize a system frequency. SOLUTION: This power plant comprises a combustor 1, a gas turbine having a turbine 3, and a generator 5 axially connected with the gas turbine. A fuel command limiter (LIM) 107 limiting the change of a fuel command value 107d is installed to a speed governing load control part 100, which finds a governor command value 103d based on a deviation of a generating command value 101d instructed from an intermediate supply according to the variation of a system frequency and generated power 102d, and finds a fuel command value 107d corresponding to a governing rate (R) in accordance with a deviation of the command value 103d and an axial speed 104d. The limiter (LIM) 107 sets a limit value of change rate in a manner to restrain thermal stress and instable combustion of a gas turbine, and restrain the change of the fuel command value 107 within a limit value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to load control of a thermal power plant, and more particularly to a speed-controlled load control system for a plant that controls load by adjusting a fuel flow rate of a gas turbine.

[0002]

2. Description of the Related Art A thermal power plant controls a fuel flow rate of a gas turbine, which is a power generation facility, or a steam flow rate of a steam turbine, according to a power generation command value from a central power supply station. In this case, in order to stabilize the system frequency (50 Hz in eastern Japan and 60 Hz in western Japan), the amount of power generation is adjusted by the speed signal according to the system contribution rate called the adjustment rate to stabilize the system frequency. That is, based on the information on the system frequency that changes according to the change in the total load of the system, for example, the flow rate of the fuel supplied to the combustor of the gas turbine is controlled based on the system contribution rate to stabilize the system frequency. This is called governor load control or governor-free control.

For example, 100% for power generation equipment with a regulation rate of 5%
2.5H, which is 5% speed when the speed is 50Hz
Fuel for 100% of the rated power output per z is added to the original fuel flow rate command value to perform the speed control load control. Since the actual system frequency is relatively stable near the rated value, the frequency fluctuation is usually 1% or less.

As shown in FIG. 10, the relationship between the system frequency and the fuel flow rate in speed-regulating load control is 100% load adjustment per 5% as described above if there is a 1% frequency fluctuation. For%, the fuel flow rate of 20% of the rated value is added / subtracted to the original command value. Further, the function of the governor load control not only stabilizes the system frequency but also serves to prevent overspeed of the turbine or the generator because it narrows down the fuel when the rotational speed of the turbine suddenly increases due to a system accident or the like. For plants with a 5% regulation rate, 1 for every 5%
Since the fuel flow rate for 00% load is operated according to the rotation speed, the load output command instantly becomes 0% when the overspeed reaches 105%, and conversely when the shaft speed exceeds 105%. In terms of output, it has a negative value, that is, it works to brake the rotation speed.

On the other hand, a gas turbine power plant supplies fuel and compressed air to a combustor, and the combustion gas drives the gas turbine. At this time, if the speed-regulating load control is performed, the fuel flow rate with high gain is adjusted as described above with respect to a slight fluctuation of the system frequency. If the fuel command value changes abruptly or frequently due to high gain, the fuel-air ratio of the combustor suddenly changes and combustion becomes unstable, leading to misfire or flashback. Further, when the fuel supply amount increases and a temperature rise or thermal stress exceeding the upper limit value occurs, the thermal stress of the gas turbine increases and accumulates. This thermal stress is a main cause of deterioration of mechanical equipment such as combustors and turbine blades, which shortens the life of the equipment.

As a countermeasure against this, for example, Japanese Patent Laid-Open No. 8-218
In No. 897, the upper limit value is set for the exhaust gas temperature of the gas turbine, the fuel supply command for speed governing load control is impaired, and when the temperature difference from the upper limit value approaches zero, priority is given to the temperature load control. Performs constant turbine load control.
As a result, we have proposed a gas turbine control method that suppresses excessive thermal stress.

[0007]

In the conventional gas turbine control in a thermal power plant, control outputs such as start control, stop control, acceleration limit control and load limiter are provided in addition to the above-mentioned speed control load control and temperature load control. The load control is performed by selecting a control signal having a low value in accordance with the combination, the operation pattern and the plant state.

However, since the combustion gas temperature approaches the upper limit value in the operation near the rated load of the gas turbine, the temperature load control is selected and the speed governing load control does not function in the control method as in the cited example, so that the system The arbitration rate set based on the power generation plan cannot be effectively maintained. On the other hand, during partial load operation where temperature load control is not selected, it becomes governor-free, but combustion instability due to changes in the control command cannot be eliminated, and equipment with difficult fuel-air ratio control such as low Nox combustors is difficult to solve. Then there are many problems. In addition, the above-mentioned generation of the thermal stress is particularly concentrated on the turbine blade, and there is a similar problem in the case of the steam turbine due to the fluctuation of the steam flow rate.

As described above, in the conventional thermal power plant, if temperature load control is performed with emphasis on life shortening due to thermal stress and combustion instability, it is not possible to suppress frequency fluctuation due to load fluctuation of the system. On the other hand, if speed regulating load control is performed to maintain the arbitration rate of the system when the system is unstable, fluctuations in the load command also increase when the system side is unstable, increasing thermal stress and combustion instability. There are conflicting problems, such as causing it.

An object of the present invention is to overcome the above-mentioned problems of the prior art and to provide a thermal power plant capable of extending the life of equipment and stabilizing combustion while maintaining the system contribution by controlling speed control load. A load control method and device are provided.

[0011]

According to the present invention to achieve the above object, a power generation command value (instruction from intermediate supply according to fluctuations in the system frequency) is given to a power plant having a turbine and a generator coupled to each other. MW command), the measured value of generated power and shaft speed, and a predetermined arbitration rate (system contribution rate) to obtain a speed-regulating load control signal, and to control the load on the turbine so as to stabilize the system frequency. In the load control method,
It is characterized in that load control of the turbine is performed by an operation command value obtained by multiplying the speed control load control signal by a load limiting function for limiting the change.

When the turbine is a gas turbine having a combustor, the operation command value is a fuel supply amount, and the load limiting function is set to suppress at least one of thermal stress and unstable combustion of the gas turbine. To do. When the turbine is a steam turbine, the operation command value is the steam supply amount, and the load limiting function is set so as to suppress the thermal stress of the steam turbine.

The load limiting function is set according to the effective contribution rate that is effectively determined from the mechanical inertia or the like with respect to the system contribution rate. Then, an optimum limit value is set by simulation or the like from the balance of the effective contribution rate and the limit value of thermal stress or the combustion stability.

The load limiting function is set by a coefficient that limits the rate of change of the speed governing load control signal or a function that variably limits the rate of change in accordance with the signal value of the speed governing load control signal. Alternatively, a time constant such as a temporary delay may be used.

Further, according to the present invention, during normal operation of the rated load or the partial load within a predetermined range of the rated speed, the load control of the turbine is performed by the operation command value multiplied by the load limiting function. On the other hand, when the shaft speed is overspeed exceeding the upper limit of the predetermined range, the speed control load control signal before the limit by the load limit function, that is, the governor-free control signal is selected to perform the load control of the turbine. It is characterized by

As a result, during normal rated operation or in the vicinity thereof, when the system frequency is close to the rated value, rapid changes in the fuel command value are limited to avoid combustion failure and thermal stress, and the shaft speed (system frequency) is increased. Overspeed (for example, 110% of rating)
(Super) can rapidly narrow down the fuel supply to prevent over-rotation of the plant.

The operation of the present invention will be described in principle. The governor-free control signal of the thermal power plant follows the change of the system frequency with a high gain to control the turbine load and try to stabilize the system frequency. Frequency fluctuations in the system mean changes in the total amount of load on the system, and when the power generation equipment is a gas turbine, the fluctuations in the fuel flow rate command value are mainly due to the values of frequency fluctuations in the system. However, according to the measured value, there is a limit to the change of the system frequency that mechanical equipment such as turbine can follow, and above a certain change rate, the load of the power generation equipment is increased without extending the function of the governor load, and thermal stress and instability occur. It is a factor that causes combustion.

The present invention has been made in view of this point, and suppresses the thermal stress of the turbine and the occurrence of unstable combustion by limiting the change of the governor load control signal to the range in which the power generation equipment can follow. In addition, the governor-free control is always functioning at the rated load or partial load operation. One of the indicators of this governor-free restriction is the effective contribution rate.

FIG. 2 shows the relationship between the system contribution rate and combustion stability and the load limiting coefficient. The load limit coefficient multiplied by the governor-free control signal is 0% (change rate is 0), and the limit coefficient is 1
Up to 00% (no limit), the theoretical system contribution rate becomes 0% to 100% as shown by the solid line in the figure. Further, the stability of combustion generally stabilizes with a smaller change, so that the limit value is highest when the limit value is 0% (load constant control), and decreases toward the limit value 100%. Similarly, thermal stress, which is stress, decreases as the load change decreases.

Assuming that the system frequency change of ± 1% is 0.5.
When it occurs at a fluctuation rate of% / sec, the actual system contribution rate becomes blunt as indicated by the dotted line due to the mechanical inertia of the power generation equipment, and in the example shown in the figure, there is a large difference in the effective contribution rate between the limit value of 70% and the limit value of 100%. There is no. In other words, there is no substantial difference in the function of stabilizing the frequency change regardless of whether the change rate of the governor-free control signal is limited or 70%.

Therefore, while the speed control load control signal is output through the limiter for limiting the rate of change to 70% to maintain the system contribution rate, the combustion failure and the heat stress are reduced by the amount of limiting the rate of change to 70%. Can be suppressed and reduced. As a result, the improved operating heat characteristics enable control load control at or near the rated load.

As described above, according to the present invention, a simple addition to the governor-free control allows the function to be constantly exhibited.
While maintaining (or substantially improving) the system contribution rate as a power generation facility, it is possible to extend the life of the facility and stabilize combustion.

Further, when the above-mentioned limiting function is added, the overspeed alleviating function of the governing load control function is lowered, but the limiting function is released at the time of overspeed or the conventional adjusting function without the limiting function is provided. Fail-safe operation becomes possible by using the fast load control function together.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 shows the configuration of a thermal power plant to which the present invention is applied. This power plant comprises a gas turbine having a combustor 1, a compressor 2, and a turbine 3 to be subjected to load control, and a generator 5 configured on one axis. The fuel from the LNG tank is adjusted by the fuel flow rate adjusting valve 4 and is supplied to the combustor 1 together with the air from the compressor 2, and the combustion gas thereof causes the turbine 3 to generate a rotational torque. Exhaust gas from the turbine 3 is subjected to heat recovery by an exhaust heat recovery boiler and exhausted from a chimney.

The air supplied to the combustor 1 via the compressor 2 is taken in from the IGV valve 6. In gas turbine control, since the compressor 2 is constantly loaded at a rated speed, the IGV valve 6 also has a fixed opening. On the other hand, the fuel flow valve 4 is activated by the load control signal from the gas turbine controller 10.
Is controlled to control the fuel supply amount. Generally, the response of the fuel flow valve is higher than that of the IGV valve by one digit or more. Further, the generated power sensor 7 provided in the generator 5, the shaft speed sensor 8 and the exhaust gas temperature sensor 9 provided in the turbine 3 respectively detect and send detection signals to the gas turbine control device 10.

FIG. 1 shows the configuration of a gas turbine control device according to one embodiment. The fuel command value 10d sent to the fuel flow valve 4 of the combustor 1 of the gas turbine is the speed control load control unit 1
00 and the other control load unit 200 command values are given by the low value selection unit (LS) 300.

The other control unit 200 has a start control unit 200-1 that becomes valid at the time of start (a command value becomes the minimum), a stop control unit 200-2 that becomes valid at the time of stop, and an upper limit of speed fluctuation (110%). Acceleration limit control unit 200-3 that becomes effective when the value exceeds the limit, and becomes effective when the power generation command value (MW command) goes out of a predetermined range, and a load limit control unit that suppresses the upper and lower limits of the load ( Road limiter) 200
-4, it becomes effective when the gas temperature exceeds the upper limit,
It has an exhaust gas temperature control unit 200-5 that protects the power generation equipment by lowering the exhaust gas temperature by setting the fuel supply to a predetermined amount, and these have the same configuration as the conventional one.

The speed governing load control unit 100 calculates the deviation between the power generation command value 101d instructed by the central power supply control office and the MW value 102d from the power generation power sensor 7 and the adder 10
1. A monitor relay (MR) 102 that obtains a positive or negative deviation value above a certain value, an analog memory (AM) 103 that generates a load set value 103d at a constant change rate that is preset according to the MR output, Load set value 103
d and the adder 104 for obtaining the deviation between the speed signal 104d from the generator speed sensor 8 and the deviation value (R)
Of the multiplier 105 and the output of this multiplier, which is the rated no-load fuel command value (FSN) which is the no-load offset value.
L) 105d is added to output a fuel flow rate command value 106d, and an adder 106, and a fuel command limiter 107 that suppresses a rapid change in the fuel flow rate command value 106d and outputs a governing load control command 100d. ing.

In the above, the rate of change set in the analog memory 103 includes conversion of the load signal into a speed component, and the load set value 103d represented by this speed component is called a governor set value. This governor set value 103d and shaft speed 104
Superimposing the deviation signal (governor-free control signal) 105d of d on the fuel command value is called governor-free control. In other words, the constantly changing total amount of load is regarded as a change in speed, and the change in speed is suppressed to stabilize the change in system frequency. This speed deviation is multiplied by a governor gain, which is the reciprocal of the arbitration rate R, to perform load control according to the arbitration rate.

For example, when the adjustment rate is 5%, 1 / R is 1
/0.05. Therefore, when a speed increase of 5% of the rated value occurs, the fuel flow rate of 100% rated of the plant is superimposed on the original load set value to supply 200% of the fuel, and conversely, a speed decrease of 5% is performed. Occurs, the fuel supply is 0% (only the offset FSNL is used).

Next, the structure and operation of the fuel command limiter 107, which is a feature of the speed governing load controller 100, will be described.

FIG. 4 shows an embodiment of the fuel command limiter. The fuel command limiter 107 is a multiplier 111 that multiplies the difference between the fuel flow rate command value 107d, which is a conventional governor-free control signal, and the previous value 106d ′ (100d) after the rate of change restriction by a constant gain K, and the multiplication result thereof. A limiter (LIM) 112 that limits the rate of change of the above with an upper / lower limit set value, and an integration circuit 113 that integrates the limited deviation value with the previous value.

As a result, when the rate of change of the fuel flow rate command value 106d is less than or equal to the upper limit (limit value of rising change rate) / lower limit (limit value of falling rate of change) of the LIM 112, the fuel flow rate command value 106d is output as it is. It When the rate of change exceeds the upper limit / lower limit, the command value 100d is held down to the set rate of change limit value. The limit value of the rate of change is set, for example, from the balance between the thermal stress and the fuel-air ratio due to the thermal dynamic characteristics of the gas turbine and the system contribution rate.

FIG. 7 shows the behavior of the plant under the controlled load control. (A) is the system frequency, (b) is the fuel command,
(C) shows changes in thermal stress of the gas turbine. The behavior of FIG. 10A is an example of the conventional governing load control without the fuel command limiter 107, and shows the case where the speed fluctuates within a range of 1% with respect to the rated 100%.

A plant with a regulation rate of 5% superimposes a fuel command of 20% on a speed fluctuation of 1%, so that (a)
The fuel command value 107d of (b) follows the fluctuation of the speed (system frequency). At this time, the thermal stress of the gas turbine shows a tendency according to the fuel command value and the fluctuation of the system frequency,
As shown in (c), a large thermal stress may be generated where the fuel command value greatly changes, and the thermal stress limit value set based on the equipment specifications may be exceeded.

In the governor load control of the conventional gas turbine control system, it is usual to take no countermeasure even if the thermal stress exceeds its limit value. Only the thermal stress value generated is monitored and the observed stress Only the durability of the main engine such as life calculation was calculated by feedback of the value. Alternatively, as quoted in the prior art, the load regulation control is switched from the governor load control to the exhaust gas temperature control so that the thermal stress is controlled to be equal to or less than the limit value.

FIG. 7B shows the behavior of the plant according to the present embodiment, in which the speed control load control unit 100 is connected to the fuel command limiter 10.
This is the case where 7 is provided. The fuel command 100d in (b) changes as indicated by the solid line, with the same speed change in (a). Here, the alternate long and short dash line indicates the change rate limit value by the LIM 107. Since the rate of change of the fuel command 100d is held within the limit value, the change becomes slower than the conventional command value 107d (dotted line). As a result, as shown in (c), the thermal stress can be suppressed below its limit value.

In the figure, the effect of limiting the rate of change of the fuel command is shown as an example of suppressing thermal stress, but a direct effect is also provided for avoiding combustion instability due to a sudden change in the fuel-air ratio. Needless to say. Further, the operation of the entire power generation plant keeps the operation as governor-free control for the variation of speed (system frequency). By the way, L
If the change rate limit value of the IM 107 is within the range of the effective contribution rate shown in FIG. 2, the LIM 10 for the governor-free control
The effect of the 7 limitation is virtually nonexistent.

FIG. 5 shows another embodiment of the fuel command limiter. 4 is different from FIG. 4 in that the function generators FG (1) and FG (2) for setting the upper limit / lower limit set values of the limiter 112 to constant values and to set the function values to the fuel flow rate command value are provided. . 5B and 5C, the function generator FG for upper limit is shown.
An example of the relationship between the fuel flow rate command and the limit value for (1) and the lower limit FG (2) is shown.

Thus, not only the rate of change of the fuel flow rate command value but also the absolute value of the fuel flow rate command value superimposed by the governor-free control is taken into consideration. That is, when the fuel command value is large, the rate of change is further suppressed by lowering the rising / falling set value, and conversely, when the fuel command value is small, the increase / falling setting value is increased to loosen the limit of the rate of change.
As a result, the limit value can be increased in the range of high load operation where thermal stress and combustion instability are likely to occur, so while avoiding excessive thermal stress and combustion instability, governor-free performance near the rated load can be achieved. It can be maintained at a somewhat lowered level, and the frequency stabilizing function can be secured for the grid.

FIG. 6 shows still another embodiment of the fuel command limiter. The fuel command limiter 107 of this embodiment is shown in FIG.
One or more of a combustor combustion mode, a fuel flow rate command value, an intermediately-charged power generation command value, a combustion temperature, etc. are taken into the input of the function generator of FG (1) and FG (2) of (b). More detailed restrictions can be realized according to the state of the combustor.

Furthermore, in addition to the rate of change of the fuel flow rate command value,
The LIM 114 for limiting the absolute value of the fuel flow rate is provided, and its upper limit value (the maximum value on the positive side) and its lower limit value (the maximum value on the negative side)
Has been set up. For the upper limit value and the lower limit value of the LIM 114, optimum parameter values are selected according to the state on the plant side.

As described above, the load control apparatus for a power plant according to the present embodiment is provided with a function of limiting the rate of change or the rate of change and the absolute value of the fuel flow rate command value by speed governing load control. Therefore, it is possible to suppress the combustion instability and the generation of excessive thermal stress due to the abrupt change of the command value, and it is possible to achieve the stable operation and the long life of the gas turbine while maintaining the speed control function.

Theoretically, the system contribution will be reduced by the amount by which the change in the fuel flow rate command value is limited, but if it is limited in consideration of the effective contribution rate in consideration of mechanical inertia, etc. Substantial deterioration of quick function is small.

Further, conventionally, when the change in the fuel flow rate command value is large, in the vicinity of the rated load, the limit temperature value causing thermal stress is often exceeded or combustion becomes unstable. It was necessary to interrupt control and switch to temperature load control. However, according to the present embodiment, not only partial load but also regulated load control can be performed at or near the rated load, which has the effect of substantially improving the system contribution.

Next, another embodiment of the power plant load control apparatus according to the present invention will be described. When the system load connected to the generator suddenly decreases, the supply amount and load are balanced by the fuel flow rate command value when the operation mode is normal, so the shaft rotation speed is controlled stably near the rated value. . However, when the load suddenly decreases due to a system accident or the like, the balance between the fuel flow rate command value and the load is lost, and the turbine rotation speed rapidly increases.

Since the speed control load control function is a control for stabilizing the turbine speed, it functions to narrow down the fuel when the turbine is in an overspeed state. Generally, in turbine design, turbine blades are designed to withstand stress such as centrifugal force up to a rated speed of 110%, and it is necessary to stop the blades quickly before exceeding this speed.
At this time, it is preferable from the standpoint of facility life to stop the fuel by narrowing it down rather than mechanical emergency stop.

By the way, the governing load control unit 1 shown in FIG.
Since 00 restricts the rapid change of the fuel command 100d, the deceleration function at the time of overspeed does not work sufficiently. Figure 8
In (a), the behavior of the plant when a system fault occurs in this case is shown. Immediately after the occurrence of the system accident, (a) the speed increases rapidly.
At this time, (b) the fuel flow rate command value is the command value 10 before the limit.
Since 6d (dotted line) changes to the command value 100d (solid line) after the restriction, the narrowing of the fuel is delayed and the rotational speed of the shaft exceeds the overspeed limit (generally 110%). Therefore, it is desirable that the rate of change of the fuel command from the speed governing load control device be limited during normal operation and not during overspeed.

FIG. 9 shows the configuration of the gas turbine controller according to this embodiment. The gas turbine control device 10 includes
It has both the same governing load control unit 100 as in FIG. 1 that limits the change in the fuel flow rate command value during normal operation, and a backup governor 150 that decelerates by reducing the fuel when overspeeding.

The backup speed governor 150 is the AM10.
Signal generator (SG) 15 to load set value 103d from 3
An adder 152 that calculates a governor-free control signal based on a deviation between the value added with the correction signal from 1 and the shaft speed 104d
A multiplier 153 that multiplies this control signal by a governor gain (1 / R), an adder 154 that adds a no-load offset FSNL 105d, and an overspeed governor 1 at normal times.
The fuel flow rate command 150d of 50 is composed of an adder 155 that adds a standby offset value so that the fuel flow rate command 150d becomes higher than the command value of the speed governing load control unit 100.

FIG. 8 (b) shows the behavior of the plant in which the backup speed governor is installed. The speed change in (a) is
As in the case of FIG. 9 (a), the number increases sharply from the time when the system fault occurs. The fuel flow rate command value in (b) becomes the command value 100d from the speed governing load control unit 100 before the accident occurs. At this time, since the command value 150d of the backup speed governor 150 is set high by the standby offset, the low value selection circuit 3
It is not selected by 00. After the accident, the command value 150d sharply decreases, whereas the command value 100d gradually decreases due to the change rate restriction. Therefore, 150d <1
At the timing of 00d, the backup speed governor 150
The command value 150d of is selected, and the fuel is rapidly narrowed down.
As a result, the speed is rapidly decelerated as in (a), and it is possible to avoid exceeding the overspeed limit.

In FIG. 9, the backup speed governor 150 is shown.
Alternatively, the fuel command limiter 107 of the speed governing load control unit 100 in FIG. 1 may be provided with a bypass so that the limiter 107 and the bypass are switched at a certain speed or higher.

FIG. 11 shows the behavior of the system frequency and the fuel flow rate according to this embodiment. During normal times when the system frequency changes within ± 1% of 50 Hz, the fuel flow rate changes as indicated by the solid line in accordance with the command value 100d of the speed governing load control unit 100. At this time, the command value 15 of the backup speed governor 150
0d is increased by + 20% from the command value 100d, and is on standby so as to be above the command value 100d. 1%
When 150d <100d in the above overspeed, the fuel flow rate follows the command value 150d. By the way, in the case of + 5% overspeed, the command value 150d is narrowed down by 100% of the rated value, so the actual fuel flow rate is rapidly narrowed down toward the offset value of 20%.

The load control device for a thermal power plant according to the present invention has been described above by using an example in which a gas turbine is used for power generation equipment, but the present invention is not limited to this. For example, the present invention is also applicable as a speed governor that limits thermal stress of a boiler at a subsequent stage in a combined gas turbine plant, a speed governor that limits thermal stress of a steam turbine, and the like. In these cases, the load control command may be the steam flow rate.

[0055]

According to the present invention, the turbine load control is performed with the operation command value in which the change rate or the value of the speed governing load control signal is limited. It has the effect of avoiding heat stress and poor combustion.

In addition to this effect, it becomes possible to control the speed governing load in the vicinity of the rated load, and the system contribution rate can be substantially improved.

Further, since the change of the governing load control signal is limited in the normal time and the limitation is released in the case of overspeed, the narrowing action originally possessed by the governor-free control can be exerted and the plant can be operated in a fail-safe manner. There is.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power plant control system according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a concept of an effective contribution rate which is one index of the limitation of the load command value according to the present invention.

FIG. 3 is a configuration diagram showing an example (gas turbine system) of a power plant to which the present invention is applied.

FIG. 4 is a configuration diagram showing an embodiment of a fuel command limiter.

FIG. 5 is an explanatory diagram showing a configuration and a limiting characteristic of another embodiment of the fuel command limiter.

FIG. 6 is a configuration diagram showing still another embodiment of the fuel command limiter.

FIG. 7 is a time chart showing plant behavior under conventional control and control according to the first embodiment.

FIG. 8 is a time chart showing the behavior of speed and fuel command under the control of the first and second embodiments.

FIG. 9 is a configuration diagram of a power plant control system according to a second embodiment of the present invention.

FIG. 10 is a change pattern diagram showing the relationship between the system frequency and the fuel flow rate corresponding to the arbitration rate in the conventional governor load control.

FIG. 11 is a change pattern diagram showing the relationship between the system frequency and the fuel flow rate corresponding to the arbitration rate in the speed regulating load control according to the second embodiment (including the first embodiment).

[Explanation of symbols]

1 ... Combustor, 2 ... Compressor, 3 ... Turbine, 4 ... Fuel flow valve, 5 ... Generator, 6 ... IGV valve, 7 ... Generated power sensor,
8 ... Shaft speed sensor, 9 ... Exhaust gas temperature sensor, 10 ... Gas turbine control device, 100 ... Proposed speed control load control unit, 10
1, 104, 106 ... Adder, 102 ... Monitor relay (MR), 103 ... Analog memory (AM), 105 ...
Multiplier, 107 ... Fuel command limiter (LIM), 111 ...
Multiplier, 112, 114 ... LIM, 113 ... Integrator, 1
50 ... Backup governor, 152, 154, 155 ...
Adder, 153 ... Multiplier, 200 ... Other control unit, 200
-1 ... Start control unit, 200-2 ... Stop control unit, 200-
3 ... Acceleration limit control unit, 200-4 ... Load limit control unit, 2
00-5 ... Exhaust gas temperature control unit, 300 ... Low value selection unit (L
S), 10d ... fuel command value, 100d ... speed control load control command, 150d ... backup speed governor fuel command value, 10
1d ... power generation command value (load demand), 102d ... generated power (MW), 103d ... load set value (governor command value),
104d ... Shaft speed, 105d ... Governor-free control signal,
106d ... FSNL, 107d ... Fuel flow rate command value.

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[Procedure amendment]

[Submission date] September 4, 2002 (2002.9.4)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title of the invention: Load control method for power plant

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01D 17/00 F01D 17/00 Q 17/20 17/20 D F02C 9/46 F02C 9/46 (72) Inventor Takahashi Masae 5-2-1 Omika-cho, Hitachi City, Ibaraki, Ltd. Inside the Omika Plant, Hitachi Ltd. (72) Inventor Takeshi Ishida 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture F-term inside the Omika Plant, Hitachi Ltd. (Reference) 3G071 AB01 BA02 BA04 BA09 BA11 BA22 BA31 CA09 DA05 FA01 FA02 FA05 GA01 GA04 GA05 GA06 HA01 HA02 HA04 JA03 JA04

Claims (11)

[Claims] 1. A power generation plant including a turbine and a generator connected to a shaft is adjusted from a power generation command value instructed according to fluctuations in the system frequency, a measured value of generated power or shaft speed, and a predetermined arbitration rate. In the load control method of the power plant that performs the load control of the turbine so as to stabilize the system frequency by obtaining the fast load control signal, the speed control load control signal was obtained by multiplying the load limiting function that limits the change. A load control method for a power plant, wherein the load control of the turbine is performed according to an operation command value. 2. The gas turbine according to claim 1, wherein the turbine is a gas turbine including a combustor,
The load control method for a power plant, wherein the operation command value is a fuel supply amount, and the load limiting function is set so as to suppress at least one of thermal stress and unstable combustion of the gas turbine. 3. The steam turbine according to claim 1, wherein the operation command value is a steam supply amount, and the load limiting function is set to suppress thermal stress of the steam turbine. Load control method for power plant. 4. The load limiting function according to claim 1, 2 or 3, wherein the load limiting function limits a rate of change of the speed governing load control signal, or the rate of change thereof in accordance with a signal value of the speed governing load control signal. A load control method for a power plant, wherein the load control method is set by a function for variably limiting. 5. The load limiting function according to claim 1, 2, 3 or 4, wherein the load limiting function is set in accordance with an effective contribution rate that is effectively determined from a mechanical inertia or the like with respect to a predetermined system contribution rate of the power generation equipment. And a load control method for a power plant. 6. The load control of the turbine according to any one of claims 1 to 5, at a normal time when a rated load or a partial load operation is performed in a predetermined range of a rated speed, by the operation command value multiplied by the load limiting function. When the axial speed exceeds the upper limit of the predetermined range,
A load control method for a power plant, wherein load control of the turbine is performed by the speed-regulating load control signal. 7. A power generation command instructed from an intermediate supply in accordance with a change in system frequency to a power plant having a gas turbine having a fuel supply valve, a combustor, a turbine, and a generator axially connected to the turbine. A governor load control means for determining a governor command value based on a deviation between the value (MW command) and the generated electric power, and for determining a fuel command value for a regulation ratio according to the deviation between the governor command value and the shaft speed is provided. In a load control device for a power plant that performs load control of a gas turbine so as to stabilize the frequency, a fuel command limiting device is provided in the speed control load control device to suppress thermal stress and unstable combustion of the gas turbine. A load control device for a power plant, characterized in that the change of the fuel command value is limited. 8. The fixed limiter according to claim 7, wherein the fuel command limiting means limits the rate of change of the fuel command value within a fixed coefficient, and the function having the rate of change of the fuel command value as a predetermined input variable. A load control device for a power plant, which is configured as a function-type limiter for limiting the value within a value. 9. The load control device for a power plant according to claim 8, wherein the fuel command value is used as the predetermined input. 10. The load control device for a power plant according to claim 8 or 9, wherein the fuel command limiting means is provided with a limiter for limiting the rate of change of the fuel command value after limiting the rate of change. 11. The fuel flow rate command value for the first arbitration rate according to the deviation between the governor command value and the shaft speed according to claim 8, 9 or 10, and an offset value is added to the fuel flow rate command value. In the normal state, the backup speed adjusting means is set to exceed the first fuel command value from the fuel command limiting means to obtain the second fuel command value, the first fuel command value and the second fuel command value. Is provided with a low value selection means for selecting the smaller one, and in the normal time, the first fuel command value that limits the change,
A load control device for a power plant, wherein load control is performed by the second fuel command value that does not limit changes during acceleration.