JP2013130171A - Combined plant and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combined plant capable of maintaining a stable output without reducing the efficiency upon a reduction or increase of a required output, and to provide a control method thereof.SOLUTION: The combined plant includes: a steam turbine 10 driven by steam generated using waste heat of a gas turbine 2; a steam drum 5 for generating steam using condensed water overheated by a waste heat recovery boiler 11 included in the gas turbine 2; a steam regulator valve 7 for adjusting supply of the steam generated by the steam drum 5 to the steam turbine 10; and a control device 30 for changing a combustion region of a combustor 9 included in the gas turbine 2 in response to the variation in the required output, and controlling the steam regulator valve 7 with a supply control signal for equalizing the total of a steam turbine output Sout and a gas turbine output Gout with the required output in response to the change of the combustion region. The control method of the plant is also provided.

Description

  The present invention relates to a combined plant including a gas turbine and a steam turbine, and a control method thereof.

  In a combined plant including a gas turbine and a steam turbine, the output may change suddenly when changing the combustion region combusted by the combustor of the gas turbine. In order to solve such a problem, there is a technique disclosed in Patent Document 1. According to the technology disclosed in Patent Document 1, it is possible to avoid a sudden change in the output of the gas turbine when the combustion region of the combustor provided in the gas turbine is changed, and to maintain a stable operation.

JP 09-287414 A

However, in the technique disclosed in Patent Document 1, when the output of the combined plant is reduced, the output of the steam turbine is reduced in order to limit the change of the combustion region of the combustor in the gas turbine.
When maintaining the output of the combined plant at a low output by such a control method, the operation of the combined plant is continued in a state where the output of the steam turbine is reduced, so that the efficiency is greatly reduced.

  Therefore, an object of the present invention is to provide a combined plant that can maintain a stable output without reducing efficiency when the required output is reduced or increased, and a control method thereof.

  In order to solve the above problems, the present invention provides a gas turbine having a combustor divided into at least two combustion regions, a steam turbine to which steam generated using exhaust heat of the gas turbine is supplied, and the steam A condenser that condenses the steam that has driven the turbine, a waste heat recovery boiler that superheats the condensate condensed in the condenser with the exhaust heat, and the condensate that is overheated in the exhaust heat recovery boiler. There is a need for a steam drum that generates the steam, and a steam supply amount adjusting device that adjusts a steam supply amount of the steam generated in the steam drum to the steam turbine to adjust a steam turbine output of the steam turbine. The combustion region is changed according to the change in the output, and the total of the steam turbine output and the gas turbine output of the gas turbine is requested in response to the change in the combustion region. To a control device for controlling the steam supply amount adjusting apparatus at a feed rate control signal for equalizing the output, the combined plant provided with a control method thereof.

  ADVANTAGE OF THE INVENTION According to this invention, the combined plant which can maintain the stable output without reducing efficiency at the time of the fall of the required output or an increase, and its control method can be provided.

It is a block diagram of a combined plant. (A) is a figure which shows the output of a combined plant at the time of fall of power generation output command value, (b) is a figure which shows an example of the output sudden change of the gas turbine which generate | occur | produces at the time of fall of power generation output command value. (A) is a figure which shows the output of a combined plant at the time of raise of power generation output command value, (b) is a figure which shows an example of the output change of the gas turbine which generate | occur | produces at the time of raise of power generation output command value. (A) is a figure which shows the control block which sets a steam control valve opening degree instruction | command, (b) is a figure which shows the logic which sets an output selection instruction | command. (A), (b) is a figure which shows the steam turbine output which cancels the output sudden change which arises in a gas turbine. It is a figure which shows the control block which sets BP valve opening degree instruction | command.

<< First Embodiment >>
Hereinafter, a first embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the combined plant 1 according to the first embodiment includes a gas turbine 2 that drives a gas turbine generator G1, and at least a high-pressure turbine 10H and a low-pressure turbine 10L, and drives the steam turbine generator G2. And a steam turbine 10 that is controlled by the control device 30.
The gas turbine 2 and the steam turbine 10 may be connected in series with one shaft, and may be a single shaft type combined plant (not shown) that drives one generator with one shaft.

  The gas turbine 2 uses a combustor 9 including a plurality (two in FIG. 1) of fuel flow control valves 3 (3a, 3b) for switching fuel supply during operation, and exhaust heat of the gas turbine 2. Then, a plurality of steam drums 5 (three in FIG. 1, a high pressure drum 5H, an intermediate pressure drum 5M, and a low pressure drum 5L in FIG. 1) and exhaust heat recovery that overheats the condensate condensed in the condenser 27. And a boiler 11.

In order to reduce nitrogen oxide (NOx) contained in the exhaust gas of the gas turbine 2, it is preferable that the combustion region of the combustor 9 can be changed during partial load operation. For example, as shown in FIG. 1, the combustor 9 is divided into two combustion regions (a first region 9a and a second region 9b), and the fuel flow control valve 3a adjusts the amount of fuel supplied to the first region 9a, The fuel flow rate adjusting valve 3b is configured to adjust the fuel supply amount to the second region 9b. During partial load operation, control is performed so as to burn in one region (for example, the second region 9b).
Of course, the number of combustion regions is not limited to two, and may be a combustor 9 having combustion regions divided into three or more.

Further, the exhaust heat recovery boiler 11 is configured to superheat the condensate with exhaust heat contained in the exhaust gas of the gas turbine 2, and from the upstream side of the exhaust gas flow, the high pressure superheater 4H, the intermediate pressure superheater 4M, the low pressure superheater. There are three superheaters 4 of the vessel 4L.
The superheater 4 (high pressure superheater 4H, medium pressure superheater 4M, low pressure superheater 4L) superheats the steam generated in the steam drum 5 (high pressure drum 5H, medium pressure drum 5M, low pressure drum 5L), and the steam control valve 7 Steam via a main steam pipe 6 (high pressure main steam pipe 6H, medium pressure main steam pipe 6M, low pressure main steam pipe 6L) equipped with (high pressure steam control valve 7H, medium pressure steam control valve 7M, low pressure steam control valve 7L) The turbine 10 (high pressure turbine 10H, low pressure turbine 10L) is configured to be supplied.
The steam control valve 7 (the high pressure steam control valve 7H, the medium pressure steam control valve 7M, and the low pressure steam control valve 7L) functions as a steam supply amount adjusting device that adjusts the amount of steam supplied to the steam turbine 10.

Specifically, the steam (high-pressure main steam) generated in the high-pressure drum 5H is superheated by the high-pressure superheater 4H, flows through the high-pressure main steam pipe 6H, and is supplied to the high-pressure turbine 10H. The flow rate of the high-pressure main steam in the high-pressure main steam pipe 6H (the amount of high-pressure main steam supplied to the high-pressure turbine 10H) is adjusted by the high-pressure main steam control valve 7H.
The steam (intermediate pressure main steam) generated in the intermediate pressure drum 5M is superheated by the intermediate pressure superheater 4M, flows through the intermediate pressure main steam pipe 6M, and is supplied to the high pressure side of the low pressure turbine 10L. The flow rate of the medium pressure main steam in the medium pressure main steam pipe 6M (the amount of medium pressure main steam supplied to the low pressure turbine 10L) is adjusted by the medium pressure main steam control valve 7M.
Further, the steam (low pressure main steam) generated in the low pressure drum 5L is superheated by the low pressure superheater 4L, flows through the low pressure main steam pipe 6L, and is supplied to the low pressure side of the low pressure turbine 10L. The flow rate of the low-pressure main steam in the low-pressure main steam pipe 6L (low-pressure main steam supply amount to the low-pressure turbine 10L) is adjusted by the low-pressure main steam control valve 7L.
The high-pressure main steam pipe 6H, the medium-pressure main steam pipe 6M, and the low-pressure main steam pipe 6L are respectively provided with a high-pressure main steam pressure gauge 8H that measures the pressure of the high-pressure main steam and an intermediate pressure that measures the pressure of the medium- and high-pressure main steam. A main steam pressure gauge 8M and a low pressure main steam pressure gauge 8L for measuring the pressure of the low pressure main steam are provided.

  The high-pressure main steam pipe 6H includes a high-pressure turbine bypass pipe 16H that bypasses the steam turbine 10 and sends the high-pressure main steam generated in the high-pressure drum 5H to the condenser 27. The medium-pressure main steam pipe 6M includes An intermediate pressure turbine bypass pipe 16M is provided to send the intermediate pressure main steam generated in the intermediate pressure drum 5M to the condenser 27 by bypassing the steam turbine 10, and the low pressure main steam pipe 6L includes the low pressure main steam generated in the low pressure drum 5L. A low-pressure turbine bypass pipe 16 </ b> L is provided that bypasses the steam turbine 10 and sends the steam to the condenser 27.

Further, the high pressure turbine bypass pipe 16H is provided with a high pressure turbine bypass valve 17H for adjusting the flow rate of the high pressure main steam, and the intermediate pressure turbine bypass pipe 16M is provided with an intermediate pressure turbine bypass valve 17M for adjusting the flow rate of the intermediate pressure main steam. The low pressure turbine bypass pipe 16L is provided with a low pressure turbine bypass valve 17L for adjusting the flow rate of the low pressure main steam. Hereinafter, the high pressure turbine bypass pipe 16H, the intermediate pressure turbine bypass pipe 16M, and the low pressure turbine bypass pipe 16L are collectively referred to as a turbine bypass pipe 16, and are referred to as a high pressure turbine bypass valve 17H, an intermediate pressure turbine bypass valve 17M, and a low pressure turbine bypass. The valve 17L is collectively referred to as a turbine bypass valve 17.
The turbine bypass valve 17 functions as a bypass flow rate adjusting device that adjusts the flow rate of steam in the turbine bypass pipe 16. When the combined plant 1 performs rated operation, the turbine bypass valve 17 is closed, and all the steam generated in the steam drum 5 is supplied to the steam turbine 10.

  The gas turbine generator G1 includes a gas turbine output meter 20 that measures output (for example, electric power), and the steam turbine generator G2 includes a steam turbine output meter 22 that measures output (for example, electric power).

The control device 30 that controls the combined plant 1 configured as described above generates power generated by the combined plant 1 (required output) by the gas turbine generator G1 and the steam turbine generator G2. The combined plant 1 is controlled.
For example, the control device 30 sets a command value (power generation output command value (MWD: Mega Watt Demand)) for controlling the combined plant 1 to be equal to the output required for the combined plant 1, and generates power generated by the gas turbine generator G1. And the gas turbine 2 and the steam turbine 10 are controlled so that the sum of the power generated by the steam turbine generator G2 becomes the power generation output command value MWD.

  When the required output decreases, the control device 30 decreases the power generation output command value MWD. When the power generation output command value MWD falls below a predetermined value, the control device 30 performs combustion in the combustor 9 of the gas turbine 2. Is partially stopped to lower the output.

  For example, in the case where the combustor 9 divided into two combustion regions (first region 9a and second region 9b) is provided, the control device 30 allows the two fuel flow rate control valves when the power generation output command value MWD is higher than a predetermined value. The valves 3a and 3b are opened to supply fuel to the first region 9a and the second region 9b. When the power generation output command value MWD becomes lower than the predetermined value, the control device 30 closes one of the two fuel flow rate control valves 3a and 3b (for example, the fuel flow rate control valve 3a) to the first region 9a. Stop supplying fuel. In the gas turbine 2, only the second region 9b continues to burn.

When the power generation output command value MWD of the combined plant 1 thus decreases, the control device 30 stops a part of the combustor 9 (for example, the first region 9a) and changes the combustion region.
However, the output of the gas turbine 2 (gas turbine output Gout) is disturbed for a short time when the combustion region is changed so that a part of the combustor 9 stops, and the output of the combined plant 1 (plant output Pout) is accordingly reduced. May be disturbed for a short time. That is, the plant output Pout of the combined plant 1 may be disturbed over a short period of time, for example, the output power may be instantaneously disturbed (for example, a few tens of seconds).

  Therefore, the combined plant 1 according to the first embodiment is configured such that the plant output Pout is stabilized when the combustion region of the combustor 9 is changed. Specifically, the disturbance of the gas turbine output Gout generated in the gas turbine 2 is canceled by the output of the steam turbine 10 (steam turbine output Sout), and the plant output Pout of the combined plant 1 is stabilized.

  For example, as shown in FIG. 2A, when the power generation output command value MWD (broken line) decreases as the required output decreases, the plant output Pout (solid line) of the combined plant 1 is the power generation output command value. Decreases in response to a decrease in MWD. When the power generation output command value MWD is reduced to a predetermined value (changed output upper limit OPu), the control device 30 (see FIG. 1) closes the fuel flow rate adjustment valve 3a (see FIG. 1) and closes the first region 9a (see FIG. 1). 1) is stopped. At this time (when the combustion region is changed), the plant output Pout instantaneously increases (section A). Thereafter, the plant output Pout rapidly decreases (section B), and when the power generation output command value MWD becomes equal to or less than a predetermined value (changed output lower limit OPd), the plant output Pout stably decreases. This is because the gas turbine output Gout of the gas turbine 2 is disturbed as indicated by the alternate long and short dash line as the combustion region of the combustor 9 is changed as shown in FIG.

  Further, for example, as shown in FIG. 3A, when the power generation output command value MWD (broken line) increases as the required output increases, the plant output Pout (solid line) of the combined plant 1 is the power generation output. It rises corresponding to the rise of the command value MWD. When the power generation output command value MWD increases to a predetermined value (changed output lower limit OPd), the control device 30 (see FIG. 1) opens the fuel flow rate control valve 3a and burns in the first region 9a (see FIG. 1). To start. At this time (when the combustion region is changed), the plant output Pout instantaneously decreases (section C). Thereafter, when the plant output Pout rapidly increases (section D) and the power generation output command value MWD becomes equal to or greater than a predetermined value (changed output upper limit OPu), the plant output Pout stably increases. This is because the gas turbine output Gout of the gas turbine 2 is disturbed as indicated by the alternate long and short dash line as the combustion region of the combustor 9 is changed as shown in FIG.

Therefore, the control device 30 (see FIG. 1) of the combined plant 1 according to the first embodiment performs one fuel flow rate adjustment valve 3 (for example, fuel flow rate adjustment) shown in FIG. 1 as the power generation output command value MWD changes. When the valve 3a) is closed or when one fuel flow control valve 3 is opened, the steam turbine output Sout of the steam turbine 10 is changed so as to cancel out the turbulent output of the gas turbine 2.
Hereinafter, the disturbance of the gas turbine output Gout that occurs when the combustion region of the combustor 9 is changed is referred to as a sudden output change. That is, the state of the gas turbine output Gout in the section A and the section B in FIG. 2B and the state of the gas turbine output Gout in the section C and the section D in FIG.

In order to change the steam turbine output Sout so as to cancel the sudden output change of the gas turbine 2 (see FIG. 1), the control device 30 (see FIG. 1) causes the gas turbine output Gout to rapidly change when the power generation output command value MWD decreases. Is increased (section A), the steam turbine output Sout is decreased, and thereafter, when the gas turbine output Gout is rapidly decreased (section B), the steam turbine output Sout is increased.
When the gas turbine output Gout decreases rapidly when the power generation output command value MWD increases (section C), the control device 30 increases the steam turbine output Sout, and then the gas turbine output Gout rapidly increases. (Section D) reduces the steam turbine output Sout.

In the first embodiment, the control device 30 (see FIG. 1) adjusts the steam turbine output Sout by adjusting the valve opening degree of the steam control valve 7 (see FIG. 1).
That is, the controller 30 opens the valve opening degree of the steam control valve 7 in the section A (see FIG. 2B) where the gas turbine output Gout rapidly increases and the section D (see FIG. 3B). To reduce the steam turbine output Sout. On the other hand, in the section B where the output of the gas turbine 2 rapidly decreases (see FIG. 2B) and the section C (see FIG. 3B), the valve opening degree of the steam control valve 7 is increased. The steam turbine output Sout is increased. And the control apparatus 30 is a steam control valve so that the valve opening degree of the steam control valve 7 may be 100% (namely, full open) at the time of the sudden output change of the gas turbine 2 (end point of the section B and the section D). 7 is controlled.

In addition, when the valve opening degree of the high pressure steam control valve 7H shown in FIG. 1 changes, the steam supply amount (medium pressure steam supply amount and low pressure steam supply amount) to the low pressure turbine 10L changes, and the output of the low pressure turbine 10L changes. To do. That is, when the high-pressure steam control valve 7H is controlled, the output of the low-pressure turbine 10L changes regardless of the valve opening degrees of the intermediate-pressure steam control valve 7M and the low-pressure steam control valve 7L. From this, when the high pressure steam control valve 7H is controlled when adjusting the steam turbine output Sout, the medium pressure steam control valve 7M and the medium pressure steam control valve 7M correspond to the change in the output of the low pressure turbine 10L by the control of the high pressure steam control valve 7H. It becomes necessary to control the low pressure steam control valve 7L. This complicates the control of the intermediate pressure steam control valve 7M and the low pressure steam control valve 7L.
As described above, when the high pressure steam control valve 7H is controlled when adjusting the steam turbine output Sout, the control of the intermediate pressure steam control valve 7M and the low pressure steam control valve 7L becomes complicated. It is sometimes preferable that the high pressure steam control valve 7H is not controlled.

Therefore, in the first embodiment, the intermediate pressure main steam control valve 7M and the low pressure main steam control valve 7L are controlled to adjust the steam turbine output Sout so as to cancel the sudden output change occurring in the gas turbine 2. Hereinafter, the control of the intermediate pressure main steam control valve 7M and the low pressure main steam control valve 7L will be collectively described as control of the steam control valve 7.
In the case of a configuration that controls the high-pressure steam control valve 7H, the control device 30 controls the high-pressure steam control valve 7H in the same manner as the medium-pressure main steam control valve 7M and the low-pressure main steam control valve 7L.

The control device 30 (see FIG. 1) uses a control block shown in FIG. 4A to supply a supply amount control signal (which adjusts the valve opening of the steam control valve 7 in order to adjust the amount of steam supplied to the steam turbine 10). Set the steam control valve opening command).
With reference to (a) of FIG. 4, the procedure in which the control apparatus 30 sets a steam control valve opening degree instruction | command is demonstrated (refer FIGS. 1-3 suitably).
The control device 30 outputs the output of the gas turbine 2 measured by the gas turbine output meter 20 (output power PG1 of the gas turbine generator G1) and the output of the steam turbine 10 measured by the steam turbine output meter 22 (of the steam turbine generator G2). The output power PG2) is added by the adder 301 (PG1 + PG2) to obtain an actual output value of the combined plant 1. Then, the control device 30 calculates a deviation (output deviation ΔW) obtained by subtracting the actual output value from the power generation output command value MWD by the adder / subtractor 302, and calculates the output deviation by PI calculation in the PI (proportional / integral) calculator 303. A control amount (output control amount) for controlling the steam turbine 10 is calculated so that ΔW is zero. In the first embodiment, the PI calculator 303 uses, as an output control amount, the valve opening degree of the steam control valve 7 (steam control valve opening degree) such that the steam turbine 10 outputs an output at which the calculated output deviation ΔW becomes zero. Set.

  When the output deviation ΔW is positive, the PI calculator 303 determines that the actually measured output value of the combined plant 1 is insufficient for the power generation output command value MWD, and the steam adjustment is performed so that the valve opening degree of the steam control valve 7 is increased. Set the valve opening. On the other hand, when the output deviation ΔW is negative, the PI calculator 303 determines that the actually measured output value of the combined plant 1 exceeds the power generation output command value MWD, and steam is controlled so that the valve opening degree of the steam control valve 7 becomes small. Set the valve opening.

  In the combined plant 1 according to the present embodiment, the steam control valve 7 is controlled by a control signal (steam control valve opening command) for setting the opening of the steam control valve 7 to the set steam control valve opening. Thus, the sum of the gas turbine output Gout and the steam turbine output Sout can be made equal to the power generation output command value MWD (required output).

  Further, in order to improve the response speed of the change in the output of the steam turbine 10 corresponding to the change in the output deviation ΔW, the output sudden change of the gas turbine 2 is predicted in advance based on the power generation output command value MWD and the predicted output sudden change is supported. It is good also as a structure which sets the valve opening degree of the steam control valve 7 so that it may, and controls the steam control valve 7 based on the set valve opening degree.

A sudden change in the output of the gas turbine 2 as shown in FIGS. 2B and 3B occurs in response to a change in the power generation output command value MWD. In other words, the control device 30 can predict a sudden output change of the gas turbine 2 based on the value of the power generation output command value MWD.
Therefore, a configuration is provided with function generators 304 and 305 that predict a sudden change in the output of the gas turbine 2 according to the value of the power generation output command value MWD, and further predict the valve opening degree of the steam control valve 7 in advance according to the prediction. It is good.

For example, the sudden change in the output of the gas turbine 2 due to the decrease in the power generation output command value MWD occurs in a unique generation pattern for each individual gas turbine 2. Therefore, if the occurrence pattern of the sudden output change is measured for each gas turbine 2 in advance, the control device 30 starts and ends the sudden output change (start point of the section A) and ends (the end point of the section B), and the output in the sudden output change. A change from the increase to the output decrease (boundary point between the sections A and B) can be predicted based on the change in the power generation output command value MWD. That is, changes in the steam turbine output Sout and the gas turbine output Gout when the power generation output command value MWD decreases can be predicted based on the change in the power generation output command value MWD.
Furthermore, a change in the output deviation ΔW between the plant output Pout of the combined plant 1 and the power generation output command value MWD can also be predicted based on the change in the power generation output command value MWD.

  Therefore, the control device 30 corresponds to a delay time from when the valve opening degree of the steam control valve 7 is changed to when the output of the steam turbine 10 is changed by the function generator 304 when the power generation output command value MWD decreases. The previous output deviation ΔW is predicted as the predicted deviation ΔWd for the amount of time. Then, the control device 30 adds the valve opening of the steam control valve 7 necessary for setting the predicted deviation ΔWd to zero with the adder 306 to the steam control valve opening set by the PI calculator 303.

  Similarly, a sudden change in the output of the gas turbine 2 accompanying an increase in the power generation output command value MWD also occurs as a unique generation pattern for each individual gas turbine 2. Therefore, if the occurrence pattern of the sudden output change is measured for each gas turbine 2 in advance, the control device 30 starts and ends the sudden output change (the start point of the section C) and ends (the end point of the section D), and the output in the sudden output change. A change from a decrease to an output increase (boundary point between section C and section D) can also be predicted based on a change in the power generation output command value MWD. That is, the change in the gas turbine output Gout when the power generation output command value MWD increases can be predicted based on the change in the power generation output command value MWD.

  Therefore, the control device 30 corresponds to a delay time from when the valve opening degree of the steam control valve 7 is changed to when the output of the steam turbine 10 is changed by the function generator 305 when the power generation output command value MWD increases. The previous output deviation ΔW is predicted as the predicted deviation ΔWu for the time to be performed. Then, the control device 30 adds the valve opening of the steam control valve 7 necessary for setting the predicted deviation ΔWu to zero with the adder 307 to the steam control valve opening set by the PI calculator 303.

  The predicted deviations ΔWd and ΔWu are differences between the power generation output command value MWD and the plant output Pout, and the relationship between the magnitudes of the predicted deviations ΔWd and ΔWu and the valve opening degree of the steam control valve 7 can be measured by experimental measurement or the like. Therefore, if the map indicating the relationship between the magnitudes of the predicted deviations ΔWd and ΔWu and the valve opening degree of the steam control valve 7 is set in advance and stored in a storage unit (not shown) of the control device 30, the control device 30 is The valve opening degree of the steam control valve 7 necessary for setting the predicted deviations ΔWd and ΔWu to zero can be easily calculated.

When the steam control valve 7 is fully open (the valve opening is 100%), the steam supply amount to the steam turbine 10 is maximized, and the steam supply amount to the steam turbine 10 is increased in order to cancel out the sudden change in the output of the gas turbine 2. I can't let you. That is, when the steam control valve 7 is fully open, the output of the steam turbine 10 cannot be increased so as to cancel the sudden change in the output of the gas turbine 2.
Therefore, when the power generation output command value MWD increases, the control device 30 sets the valve opening of the steam control valve 7 to, for example, half-open (valve open) before the sudden output change of the gas turbine 2 occurs, that is, before the combustion region is changed. The amount of steam supplied to the low-pressure turbine 10L is decreased by setting a predetermined valve opening degree that is closed from the fully open state, such as an opening degree of 50%. The valve opening at this time is preferably set as appropriate.
With this configuration, the control device 30 can adjust the valve opening degree of the steam control valve 7 corresponding to the power generation output command value MWD, and can increase and decrease the steam supply amount to the low-pressure turbine 10L.

  Specifically, the function generator 305 raises the steam control valve when the power generation output command value MWD rises and reaches a predetermined value set in advance (however, a predetermined value lower than the change output lower limit OPd at which sudden output change occurs). 7 is made smaller than the fully open position to reduce the amount of steam supplied to the steam turbine 10. At this time, the control device 30 increases the gas turbine output Gout by increasing the valve opening degree of the opened fuel flow rate control valve 3 (for example, the fuel flow rate control valve 3b) so that the plant output Pout does not decrease. To do. In this state, the function generator 305 of the control device 30 predicts the predicted deviation ΔWu based on the increase in the power generation output command value MWD, and sets the valve opening required to make the predicted deviation ΔWu zero by the PI calculator 303. The adder 307 adds to the steam control valve opening.

2 (b) and FIG. 3 (b) are merely examples of the occurrence pattern of the sudden change in output, for example, when the combustion region of the combustor 9 is changed when the power generation output command value MWD decreases. There is also a gas turbine 2 having a generation pattern in which the turbine output Gout temporarily decreases.
When the output sudden change of the gas turbine 2 has such a generation pattern, the function generator 304 of the control device 30 reduces the power generation output command value MWD to a predetermined value that is set in advance (however, a change that causes an output sudden change occurs). A configuration in which the valve opening degree of the steam control valve 7 is set to be smaller than fully open when a predetermined value higher than the output upper limit OPu is reached is preferable.
With this configuration, when a sudden output change occurs when the combustion region of the combustor 9 is changed and the gas turbine output Gout decreases, the function generator 304 increases the valve opening degree of the steam control valve 7 to increase the steam turbine output Sout. It is possible to cancel the sudden change in output of the gas turbine 2 by raising it.

Reference numerals 308 and 309 are correctors for correcting the steam control valve opening.
When the steam control valve opening output from the adders 306 and 307 is smaller than the lower limit value (lower limit opening) of the steam control valve 7, the corrector 308 sets the steam control valve opening to the lower limit. Set. When the steam control valve opening output from the adders 306 and 307 is larger than the upper limit value (upper limit opening) of the steam control valve 7, the corrector 309 opens the steam control valve opening to the upper limit. Set to degrees.

  The lower limit opening and the upper limit opening are set for each of the intermediate pressure steam control valve 7M and the low pressure steam control valve 7L. The correctors 308 and 309 control the steam for each of the medium pressure steam control valve 7M and the low pressure steam control valve 7L. Correct the valve opening.

Then, one of the steam control valve opening corrected by the correctors 308 and 309 and the upper limit opening of the steam control valve 7 is selected by the selector 311.
The selector 311 selects one of the steam control valve opening and the upper limit opening based on the output selection command generated by the selection command generator 310.
For example, the selector 311 is configured such that the steam control valve opening is selected when the output selection command is “1”, and the upper limit opening is selected when the output selection command is “0”.
Details of the output selection command generated by the selection command generator 310 will be described later.

One of the steam control valve opening and the upper limit opening selected by the selector 311 is input to the low value selector 312 as the first opening.
Further, the low value selector 312 includes a steam control unit for maintaining the steam pressure in the main steam pipe 6 (the high pressure main steam pipe 6H, the medium pressure main steam pipe 6M, and the low pressure main steam pipe 6L) at a predetermined set pressure. The valve opening (second opening) of the valve 7 and the valve opening (third opening) of the steam control valve 7 for maintaining the rotation speed of the steam turbine 10 at a predetermined value are input.

The predetermined set pressure in the main steam pipe 6 is a steam pressure that is appropriately set for each of the high-pressure main steam pipe 6H, the medium-pressure main steam pipe 6M, and the low-pressure main steam pipe 6L as operating conditions during rated operation of the combined plant 1. is there.
Further, the predetermined value of the rotational speed of the steam turbine 10 is, for example, a target rotational speed when the steam turbine 10 is accelerated.

And the minimum value among the input 1st opening degree, 2nd opening degree, and 3rd opening degree is selected by the low value selector 312, and the opening degree of the steam control valve 7 is made into the output valve opening degree. A control signal (steam control valve opening command) is set.
The control device 30 controls the steam control valve 7 with the set steam control valve opening command.
In this way, it is possible to prevent the steam control valve 7 from opening excessively by the configuration in which the minimum value among the first opening, the second opening, and the third opening is selected by the low value selector 312. The combined plant 1 can be operated stably.

The selection command generator 310 sets an output selection command with the logic shown in FIG.
“Condition 1” shown in FIG. 4B is a condition when the power generation output command value MWD is decreasing, and is set to “1” when all of the following three conditions are “true”. The
(1-1) The power generation output command value MWD is decreasing.
(1-2) The value of the power generation output command value MWD is equal to or less than a value larger than the change output upper limit OPu by a predetermined value α.
(1-3) The value of the power generation output command value MWD is greater than or equal to the change output lower limit OPd.

The predetermined value α here is a change that is predicted to decrease the power generation output command value MWD during the delay time from when the valve opening degree of the steam control valve 7 changes until the output of the steam turbine 10 changes. Amount.
By setting such a predetermined value α, the selection command generator 310 can output “1” before the power generation output command value MWD reaches the change output upper limit OPu, and as a result, the gas turbine output Gout. Prior to this change, the output selection command can be set to “1”.

“Condition 2” shown in FIG. 4B is a condition when the power generation output command value MWD is increasing, and “1” is set when all of the following three conditions are “true”. Is set.
(2-1) The power generation output command value MWD is increasing.
(2-2) The value of the power generation output command value MWD is equal to or greater than a value smaller than the change output lower limit OPd by a predetermined value β.
(2-3) The value of the power generation output command value MWD is less than or equal to the change output upper limit OPu.

Here, the predetermined value β is a change that is predicted to increase the power generation output command value MWD during a delay time from when the valve opening degree of the steam control valve 7 changes until the output of the steam turbine 10 changes. Amount.
By setting such a predetermined value β, the selection command generator 310 can output “1” before the power generation output command value MWD reaches the change output lower limit OPd, and consequently the gas turbine output Gout. Prior to this change, the output selection command can be set to “1”.

Further, when “1” is set in any one of condition 1 and condition 2, if both the gas turbine 2 and the steam turbine 10 are in operation, the selection command generator 310 sets “1”. Otherwise, “0” is set and the set value is output as an output selection command.
The output selection command (“0” or “1”) set in this way is input to the selector 311 and one of the steam control valve opening and the upper limit opening is selected based on the output selection command.

Thus, the control apparatus 30 (refer FIG. 1) of the combined plant 1 which concerns on 1st Embodiment is the gas turbine 2 (FIG. 1) when the power generation output command value MWD falls or when the power generation output command value MWD rises. When the combustion region of the combustor 9 (see FIG. 1) is changed, the steam turbine output Sout is adjusted so as to cancel the sudden output change that occurs in the gas turbine 2.
Further, the control device 30 predicts a sudden output change in the gas turbine 2 (see FIG. 1) based on the power generation output command value MWD, and the steam turbine after the valve opening degree of the steam control valve 7 (see FIG. 1) changes. The valve opening degree of the steam control valve 7 is adjusted prior to the change in the gas turbine output Gout by the delay time until the output Sout changes.

  With this configuration, as shown in FIGS. 5 (a) and 5 (b), an output sudden change (one point) that occurs in the gas turbine 2 (see FIG. 1) that occurs when the power generation output command value MWD decreases or rises (broken line). The steam turbine output Sout (two-dot chain line) can be adjusted so as to cancel the chain line), and the plant output Pout (solid line) of the combined plant 1 can be stabilized.

  Further, since “1” is output from the selection command generator 310 (see FIG. 4A) before the power generation output command value MWD reaches the change output upper limit OPu or the change output lower limit OPd, the control device 30 designates the steam control valve 7 with a steam control valve opening command prior to the change in the gas turbine output Gout for a delay time from when the valve opening degree of the steam control valve 7 changes until the steam turbine output Sout changes. Can be controlled.

In the first embodiment, the valve opening of the intermediate pressure main steam control valve 7M and the valve opening of the low pressure main steam control valve 7L are adjusted to be the same valve opening. A configuration in which the valve openings of the main steam control valve 7M and the low-pressure main steam control valve 7L are individually adjusted is also possible.
In this case, the medium pressure main steam control valve 7M and the low pressure main steam control valve 7L are adjusted so that the output deviation ΔW becomes zero based on the change of the output deviation ΔW when the valve opening degree of the low pressure main steam control valve 7L is adjusted independently. It is preferable to adjust the valve openings of the steam control valve 7M and the low-pressure main steam control valve 7L, respectively.

<< Second Embodiment >>
As described above, the first embodiment is configured to adjust the valve opening degree of the steam control valve 7 (see FIG. 1) to adjust the output of the steam turbine 10 (see FIG. 1), and the steam drum 5 (see FIG. 1). The output of the steam turbine 10 is adjusted by changing the amount of steam generated in 1). In this configuration, the pressure of the main steam pipe 6 (see FIG. 1) changes after the opening degree of the steam control valve 7 is adjusted, and further, a delay occurs until the steam generation amount of the steam drum 5 changes. In some cases, the steam turbine output Sout cannot be quickly adjusted.

Therefore, the turbine bypass valve 17 may be controlled together with the steam control valve 7 shown in FIG. 1 so that the steam in the main steam pipe 6 is directly introduced into the condenser 27 and the pressure in the main steam pipe 6 is adjusted.
Specifically, in order to reduce the valve opening degree of the steam control valve 7, the valve opening degree of the turbine bypass valve 17 is increased to increase the steam flow rate in the turbine bypass pipe 16 and increase the introduction amount to the condenser 27. The steam pressure in the main steam pipe 6 is maintained at a predetermined set pressure.

Further, when increasing the valve opening degree of the steam control valve 7, the valve opening degree of the turbine bypass valve 17 is decreased to lower the steam flow rate in the turbine bypass pipe 16 and to reduce the introduction amount to the condenser 27. The steam pressure in the main steam pipe 6 is maintained at a predetermined set pressure.
As described above, the predetermined set pressure in the main steam pipe 6 is appropriately set for each of the high-pressure main steam pipe 6H, the medium-pressure main steam pipe 6M, and the low-pressure main steam pipe 6L as operating conditions during rated operation of the combined plant 1. Is the steam pressure.

  As with the steam control valve 7, the operation of the high pressure turbine bypass valve 17H affects the output of the low pressure turbine 10L. Therefore, the high pressure turbine bypass valve 17H is not controlled, and the intermediate pressure turbine bypass valve 17M and the low pressure turbine bypass valve are controlled. The structure which controls 17L is preferable.

  The control device 30 (see FIG. 1) adjusts the valve opening of the steam control valve 7 as in the first embodiment, and controls the turbine bypass valve 17 by the control block shown in FIG. 6 (BP valve opening). Command) (hereinafter, refer to FIGS. 1 to 3 as appropriate).

Hereinafter, although the setting of the control signal (low pressure BP valve opening command) of the low pressure turbine bypass valve 17L will be described, the same applies to the setting of the control signal (medium pressure BP valve opening command) of the intermediate pressure turbine bypass valve 17M.
When the high pressure turbine bypass valve 17H is controlled, the control device 30 similarly sets a control signal (high pressure BP valve opening command) for the high pressure turbine bypass valve 17H.

  The control device 30 sets the detection value of the low-pressure main steam pressure gauge 8L provided in the low-pressure main steam pipe 6L as an actual measurement value (low-pressure actual measurement value) of the low-pressure main steam pressure in the low-pressure main steam pipe 6L, and is set in the low-pressure main steam pipe 6L. The low pressure deviation ΔPL is calculated by subtracting the low pressure measured value from the predetermined set pressure (low pressure set pressure) by the adder / subtractor 401. The control device 30 calculates a bypass valve control command for controlling the low-pressure turbine bypass valve 17L so that the calculated low-pressure deviation ΔPL is zero by the PI calculation in the PI calculator 402. In the second embodiment, the PI calculator 402 sets, as a bypass valve control command, a command for adjusting the valve opening (low pressure BP valve opening) of the low pressure turbine bypass valve 17L so that the calculated low pressure deviation ΔPL becomes zero. . Note that the low pressure set pressure is the steam pressure of the low pressure main steam pipe 6L, which is appropriately set as an operating condition when the combined plant 1 is operated.

  When the low-pressure deviation ΔPL is positive, the PI calculator 402 determines that the low-pressure actual measurement value is smaller than the low-pressure set pressure, and decreases the low-pressure BP valve opening to increase the low-pressure actual measurement value. On the other hand, when the low-pressure deviation ΔPL is negative, the PI calculator 402 determines that the actual low-pressure value is greater than the low-pressure set pressure, and increases the low-pressure BP valve opening to lower the low-pressure actual value.

  Further, the control device 30 predicts a valve opening change (operation) of the low pressure steam control valve 7L based on the power generation output command value MWD, and controls the low pressure turbine bypass valve 17L based on the predicted valve opening change. It is good.

  For example, when the power generation output command value MWD decreases, the change in the valve opening degree of the steam control valve 7 (low pressure steam control valve 7L) for making the prediction deviation ΔWd and the prediction deviation ΔWd zero as in the first embodiment. And a function generator 403 for setting the valve opening change of the low-pressure turbine bypass valve 17L so as to correspond to the valve opening change of the low-pressure steam control valve 7L. The relationship between the valve opening change of the low-pressure main steam control valve 7L and the pressure change of the low-pressure main steam pipe 6L, and the valve opening change of the low-pressure turbine bypass valve 17L that makes the pressure change of the low-pressure main steam pipe 6L zero are preset. It is calculated by experimental measurement. Therefore, the valve opening change of the low-pressure turbine bypass valve 17L that makes the pressure change of the low-pressure main steam pipe 6L caused by the valve opening change of the low-pressure main steam control valve 7L and the valve opening change of the low-pressure main steam control valve 7L zero. A map showing the relationship between and can be easily created.

Therefore, the map may be created in advance and stored in a storage unit (not shown) of the control device 30. With such a configuration, the function generator 403 generates the map based on the change in the valve opening degree of the low-pressure main steam control valve 7L predicted from the power generation output command value MWD when the power generation output command value MWD decreases. , The amount of change in the valve opening of the low pressure turbine bypass valve 17L that makes the pressure change in the low pressure main steam pipe 6L caused by the change in the valve opening of the low pressure main steam control valve 7L zero (low pressure BP valve opening change amount ΔBLd) Can be calculated (predicted).
The low pressure BP valve opening change amount ΔBLd calculated (predicted) by the function generator 403 is added to the low pressure BP valve opening output from the PI calculator 402 by the adder 405.

Further, when the power generation output command value MWD increases, the valve opening change amount (low pressure BP valve opening change amount ΔBLu) of the low pressure turbine bypass valve 17L corresponding to the valve opening change of the low pressure main steam control valve 7L is calculated. A function generator 404 for (predicting) may be provided.
The low pressure BP valve opening change amount ΔBLu calculated (predicted) by the function generator 404 is added to the low pressure BP valve opening output from the PI calculator 402 by the adder 406.

Reference numerals 407 and 408 denote correctors that correct the low-pressure BP valve opening.
The low pressure BP valve opening obtained by adding the low pressure BP valve opening change amount ΔBLd by the adder 405 or the low pressure BP valve opening obtained by adding the low pressure BP valve opening change amount ΔBLu by the adder 406 is the low pressure turbine bypass valve. When smaller than the lower limit value of the 17 L valve opening (low pressure BP valve lower limit opening), the corrector 407 sets the low pressure BP valve opening to the lower pressure BP valve lower limit opening.
Further, the low pressure BP valve opening obtained by adding the low pressure BP valve opening change amount ΔBLd by the adder 405 or the low pressure BP valve opening obtained by adding the low pressure BP valve opening change amount ΔBLu by the adder 406 is the low pressure turbine. When larger than the upper limit value of the valve opening degree of the bypass valve 17L (low pressure BP valve upper limit opening degree), the corrector 408 sets the low pressure BP valve opening degree to the low pressure BP valve upper limit opening degree.

One of the low-pressure BP valve opening and the low-pressure BP valve upper limit opening corrected by the correction devices 407 and 408 is selected by the selector 410.
The selector 410 selects one of the low pressure BP valve opening and the low pressure BP valve upper limit opening based on the output selection command generated by the selection command generator 409.
For example, the selector 410 is configured such that the low pressure BP valve opening is selected when the output selection command is “1”, and the low pressure BP valve upper limit opening is selected when the output selection command is “0”. The
Note that the selection command generator 409 generates an output selection command with the same logic as the selection command generator 310 shown in FIG.

  Similarly to the selection command generator 310, the selection command generator 409 can output “1” before the power generation output command value MWD reaches the change output upper limit OPu or the change output lower limit OPd, and the gas turbine output The output selection command can be set to “1” prior to the change of Gout. Therefore, the control device 30 works together with the steam control valve 7 that is controlled prior to the change in the gas turbine output Gout for the delay time from when the valve opening degree of the steam control valve 7 changes until the steam turbine output Sout changes. The low pressure turbine bypass valve 17L and the intermediate pressure turbine bypass valve 17M can be controlled.

One of the low pressure BP valve opening degree and the low pressure BP valve upper limit opening degree selected by the selector 410 is input to the low value selector 411 as the low pressure BP valve first opening degree. Further, the low value selector 411 receives the valve opening (low pressure BP valve second opening) of the low pressure turbine bypass valve 17L for maintaining the vapor pressure in the low pressure main steam pipe 6L at the low pressure set pressure described above. The
Then, the low value selector 411 selects a small value from the input low pressure BP valve first opening and low pressure BP valve second opening, and the valve of the low pressure turbine bypass valve 17L is selected based on the selected opening. A control signal (low pressure BP valve opening command) for setting the opening is generated to adjust the valve opening of the low pressure turbine bypass valve 17L.
As described above, the low value BP valve first opening degree and the low pressure BP valve second opening degree are selected by the low value selector 411 so that the low pressure turbine bypass valve 17L is excessively opened. The combined plant 1 can be operated stably.

The control signal (intermediate pressure BP valve opening command) for setting the valve opening of the intermediate pressure turbine bypass valve 17M is the same as the low pressure BP valve opening command, and the intermediate pressure main steam pressure gauge 8M provided in the intermediate pressure main steam pipe 6M. Is set based on the deviation (medium pressure deviation ΔPM) between the detected value (medium pressure actual measurement value) and the set pressure (medium pressure set pressure) in the medium pressure main steam pipe 6M.
The intermediate pressure setting pressure is a steam pressure of the intermediate pressure main steam pipe 6M that is appropriately set as an operation condition when the combined plant 1 is operated.

When the high pressure turbine bypass valve 17H is controlled, the control signal (high pressure BP valve opening command) for setting the valve opening of the high pressure turbine bypass valve 17H is the same as the low pressure BP valve opening command. A configuration that is set based on a deviation (high pressure deviation ΔPH) between a detected value (high pressure measured value) of the high pressure main steam pressure gauge 8H provided in the steam pipe 6H and a set pressure (high pressure set pressure) in the high pressure main steam pipe 6H. It is good.
The high-pressure set pressure in this case is also set as the steam pressure of the high-pressure main steam pipe 6 </ b> H that is appropriately set as an operating condition during the operation of the combined plant 1.

  Thus, the control apparatus 30 (refer FIG. 1) of the combined plant 1 which concerns on 2nd Embodiment is the gas turbine 2 (when power generation output command value MWD falls, or when power generation output command value MWD rises ( When the combustion region of the combustor 9 (see FIG. 1) of the combustor 9 (see FIG. 1) is changed, the steam turbine output Sout is adjusted so as to cancel the sudden change in output generated in the gas turbine 2, and the low pressure turbine bypass valve 17L and the intermediate pressure turbine bypass are adjusted. The valve 17M is opened, and the steam of the low pressure main steam pipe 6L and the medium pressure main steam pipe 6M is introduced into the condenser 27. Thereby, the pressure of the low pressure main steam pipe 6L can be maintained at the low pressure set pressure. Moreover, the pressure of the intermediate pressure main steam pipe 6M can be maintained at the intermediate pressure setting pressure.

  Further, the low pressure main steam of the low pressure main steam pipe 6L and the medium pressure main steam of the medium pressure main steam pipe 6M are introduced into the condenser 27, whereby the low pressure main steam and the medium pressure main steam to the low pressure steam turbine 10L. The supply amount is adjusted, the steam turbine output Sout can be adjusted quickly, and the steam turbine output Sout can be stabilized.

  Further, since “1” is output from the selection command generator 409 before the power generation output command value MWD reaches the change output upper limit OPu or the change output lower limit OPd, the control device 30 controls the valve of the steam control valve 7. Prior to the change of the gas turbine output Gout, the low pressure turbine bypass valve 17L, and the intermediate pressure turbine bypass valve 17M, together with the steam control valve 7, for a delay time from when the opening degree changes until the steam turbine output Sout changes. Can be configured to be controllable.

As shown in FIG. 1, the combustor 9 of the combined plant 1 according to the first embodiment and the second embodiment is divided into two combustion regions (a first region 9a and a second region 9b), and the combustion region is The gas turbine 2 that is changed only once is configured so that the output suddenly changes only once.
For example, in the combustor 9 divided into three or more combustion regions, the combustion region change may occur twice or more in accordance with the change in the power generation output command value MWD. In this case, the output sudden change of the gas turbine 2 is also 2 Occurs more than once. In this case, it is preferable that the control device 30 adjusts the steam turbine output Sout of the steam turbine 10 by the number of times that the output sudden change of the gas turbine 2 occurs.

1 Combined Plant 2 Gas Turbine 5 Steam Drum 6 Main Steam Pipe 7 Steam Control Valve (Steam Supply Control Device)
9 Combustor 9a First region (combustion region)
9b Second region (combustion region)
10 Steam Turbine 11 Waste Heat Recovery Boiler 16 Turbine Bypass Pipe 17 Turbine Bypass Valve (Bypass Flow Control Device)
27 Condenser 30 Controller Gout Gas turbine output Sout Steam turbine output

Claims (7)

A gas turbine having a combustor divided into at least two combustion zones;
A steam turbine to which steam generated using exhaust heat of the gas turbine is supplied;
A condenser that condenses the steam that has driven the steam turbine;
An exhaust heat recovery boiler that superheats the condensate condensed in the condenser with the exhaust heat;
A steam drum that generates the steam from the condensate that has been superheated by the exhaust heat recovery boiler;
A steam supply amount adjusting device for adjusting a steam turbine output of the steam turbine by adjusting a steam supply amount of the steam generated in the steam drum to the steam turbine;
The combustion region is changed according to a change in required output, and the sum of the steam turbine output and the gas turbine output of the gas turbine is made equal to the required output in response to the change in the combustion region. A control device for controlling the steam supply amount adjusting device with a supply amount control signal for;
A combined plant characterized by comprising: A main steam pipe that connects the steam drum and the steam turbine and includes the steam supply amount adjusting device;
A turbine bypass pipe for connecting the main steam pipe and the condenser and bypassing the steam turbine to introduce the steam generated in the steam drum into the condenser;
A bypass flow rate adjusting device for adjusting the flow rate of the steam in the turbine bypass pipe;
Further comprising
The controller is
The combined plant according to claim 1, wherein the bypass flow rate adjusting device is controlled together with the steam supply amount adjusting device to maintain the pressure of the main steam pipe at a predetermined set pressure. The controller is
Determining the supply amount control signal such that a sum of the gas turbine output and the steam turbine output to be predicted based on the change in the required output is equal to the required output;
The steam supply amount adjusting device is controlled by the supply amount control signal prior to the change of the gas turbine output for a delay time from the control of the steam supply amount adjusting device to the change of the output of the steam turbine. The combined plant according to claim 1, wherein the combined plant is characterized in that When the steam supply amount is maximum,
The control device controls the steam supply amount adjusting device in advance to change the steam supply amount before changing the combustion region,
The combined plant according to any one of claims 1 to 3, wherein the steam supply amount can be increased in accordance with the change in the combustion region. A gas turbine having a combustor divided into at least two combustion zones;
A steam turbine to which steam generated using exhaust heat of the gas turbine is supplied;
A condenser that condenses the steam that has driven the steam turbine;
An exhaust heat recovery boiler that superheats the condensate condensed in the condenser with the exhaust heat;
A steam drum that generates the steam from the condensate that has been superheated by the exhaust heat recovery boiler;
A steam supply amount adjusting device for adjusting a steam supply amount of the steam turbine by adjusting a steam supply amount of the steam generated in the steam drum to the steam turbine,
The combustion region is changed according to a change in the required output, and further, in response to the change in the combustion region, the sum of the gas turbine output of the gas turbine and the steam turbine output is equal to the required output. A control method, characterized by controlling the steam supply amount adjusting device.   Bypass flow rate for adjusting the flow rate of the steam introduced into the condenser by bypassing the steam turbine from the main steam pipe connecting the steam drum and the steam turbine when controlling the steam supply amount adjusting device The control method according to claim 5, wherein a control device is controlled to maintain a pressure of the main steam pipe at a predetermined set pressure.   6. The steam supply amount adjusting device is controlled prior to the change of the gas turbine output for a delay time from when the steam supply amount adjusting device is controlled to when the steam turbine output changes. Or the control method of Claim 6.

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