JP5627409B2 - Combined cycle power plant and control device - Google Patents

Description

  The present invention relates to a combined cycle power plant having a plurality of gas turbines and a control device that controls the combined cycle power plant.

  In a combined cycle power plant having multiple gas turbines, one or more gas turbines and an HRSG (Heat Recovery Steam Generator) are already in operation and supplying steam to the steam turbine. When the gas turbine and the HRSG are started, the supply of steam from the newly started HRSG to the steam turbine is started when the steam temperature of the newly started HRSG is low. The temperature changes rapidly and thermal stress is generated, which may adversely affect the life of the blades and rotors.

In contrast, if the steam temperature of the newly started HRSG becomes the same as the inlet temperature of the steam turbine and the steam supply to the steam turbine is started, the generation of thermal stress can be avoided.
However, until the steam temperature of the newly activated HRSG becomes the same as the steam temperature of the already operating HRSG, the newly activated HRSG steam cannot be used for power generation. If steam supply to the steam turbine can be started at an earlier stage, the power generation amount of the steam turbine can be increased.

This point will be described with reference to FIGS.
FIG. 6 is a diagram illustrating an example of main steam piping of a conventional combined cycle power plant. In the combined cycle power plant 1001 in the figure, when the gas turbine 1011 and the HRSG 1021 are already in operation and the governor valve 1051 is fully open, the high-pressure steam is generated by the heat of the steam supplied from the high-pressure drum 1211 of the HRSG 1021. The inlet steam temperature of the turbine 1031 is high. When the gas turbine 1012 and the HRSG 1022 are newly started from this state, when supply of steam from the high-pressure drum 1221 to the high-pressure steam turbine 1031 is started at a stage where the temperature of the steam generated by the HRSG 1022 is low, The inlet temperature of the high-pressure steam turbine 1031 rapidly decreases. Specifically, the temperature of the blades and rotors of the high-pressure steam turbine 1031 rapidly decreases, and thermal stress may occur, which may adversely affect the life of the blades and rotors.

On the other hand, if the steam supply to the steam turbine is started after the steam temperature of the high-pressure drum 1221 becomes the same as the inlet temperature of the steam turbine 1031, the generation of thermal stress can be avoided.
FIG. 7 is a graph showing an example of steam supply start timing from the high-pressure drum 1221 to the high-pressure steam turbine 1031 in the combined cycle power plant 1001 (FIG. 6).

A line L1011 in FIG. 4A indicates the inlet temperature of the high-pressure steam turbine 1031. The gas turbine 1011 and the HRSG 1021 have already been operating from time t1001 or earlier, and the high-pressure steam turbine 1031 has a constant inlet temperature when supplied with steam from the high-pressure drum 1211.
Then, at time t1001, the gas turbine 1012 and the HRSG 1022 are activated, and the steam temperature of the high-pressure drum 1221 rises as indicated by a line L1012, and at time t1005, the steam temperature of the high-pressure drum 1221 is changed to that of the gas turbine 1021. The inlet temperature is reached.

Prior to time t1005, when the governor valve 1052 is opened and the supply of steam from the high pressure drum 1221 to the high pressure steam turbine 1031 is started, the high pressure steam turbine is caused by the difference between the inlet temperature of the high pressure steam turbine 1031 and the steam temperature of the high pressure drum 1221. The temperature of the blades 1031 and the rotor suddenly decreases and thermal stress is generated, which may adversely affect the life of the blades and the rotor.
Therefore, at time t1005 when the steam temperature of the high-pressure drum 1221 reaches the inlet temperature of the high-pressure steam turbine 1031, the governor valve 1052 is opened and supply of steam from the high-pressure drum 1221 to the high-pressure steam turbine 1031 is started.

  As a result, the inlet flow rate (line L1021) of the high-pressure steam turbine 1031 increases, and accordingly, the amount of work (line L1031) of the high-pressure steam turbine 1031 increases. Here, as the “amount of work” of the high-pressure steam turbine 1031, for example, power generated by rotational driving performed by the high-pressure steam turbine 1031 out of power generated by the generator 1041 is used. The electric power generated by the rotational drive performed by the high-pressure steam turbine 1031 includes, for example, the generated power of the generator 1041, the inlet pressure, the inlet temperature and the inlet flow rate of the high-pressure steam turbine 1031, the inlet pressure, the inlet temperature of the medium-pressure steam turbine 1032 and This is estimated based on the inlet flow rate, the inlet pressure of the low-pressure steam turbine 1033, the inlet temperature, and the inlet flow rate.

  Here, between time t1001 and time t1005, the steam temperature (line L1012) of the high-pressure drum 1221 increases, but the work amount (line L1031) of the high-pressure steam turbine 1031 does not increase. That is, the high-pressure drum 1221 generates steam even before time t1005, but the steam is blocked by the governor valve 1052, and is not used for the operation of the high-pressure steam turbine 1031. If the supply of steam from the high-pressure drum 1221 to the high-pressure steam turbine 1031 can be started at an earlier timing, the work amount of the high-pressure steam turbine 1031 can be increased earlier.

  Therefore, in Patent Document 1, a first amount of steam (corresponding to HRSG steam that is already in operation) is sent to the steam turbine, and a second amount of steam (corresponding to newly activated HRSG steam). The second amount of steam fed into the steam turbine by controlling the bypass valve based on the predicted stress level in the steam turbine when the second amount of steam is fed into the steam turbine. A method is shown for adjusting the amount of steam so that the stress level of the steam turbine does not exceed a predetermined stress threshold.

JP 2009-209931 A

  However, in the method disclosed in Patent Document 1, it is possible to prevent excessive stress from being generated in the steam turbine by limiting the amount of steam of the second amount of steam sent to the steam turbine. A large amount of the second amount of steam cannot be fed into the steam turbine until the steam temperature of the steam reaches a sufficiently high temperature. Thereby, the timing which can obtain a big output from a steam turbine will be overdue.

  The present invention has been made in view of such circumstances, and an object of the present invention is to supply a larger amount of steam from a newly started HRSG to a steam turbine at an earlier stage. An object of the present invention is to provide a combined cycle power plant and a control device that do not cause adverse effects due to thermal stress.

The present invention has been made to solve the above-described problems, and a combined cycle power plant according to an aspect of the present invention includes a first gas turbine and a first gas that generates steam from exhaust gas of the first gas turbine. A steam generator, a second gas turbine, a second steam generator that generates steam from exhaust gas of the second gas turbine, a steam turbine, the first steam generator, and the steam turbine A first pipe connecting the second pipe, a second pipe connecting the second steam generation section and the steam turbine, a cooling section supplying cooling water to the first pipe, and the second steam A cooling water supply amount control unit that controls a supply amount of cooling water that the cooling unit supplies to the first pipe according to steam generated by the generation unit, and a turbine inlet temperature acquisition that acquires an inlet temperature of the steam turbine And A steam temperature acquisition unit that acquires the temperature of the steam generated by the second steam generation unit, a steam supply blocking unit that blocks steam from the second steam generation unit to the steam turbine, and the first steam The generator supplies steam to the steam turbine, the steam supply shut-off unit shuts off steam from the second steam generator to the steam turbine, and the inlet temperature of the steam turbine is the first temperature When the temperature of the steam generated by the second steam generator is higher than the inlet temperature of the steam turbine and the temperature of the steam generated by the second steam generator, the second steam generator When the supply availability determination unit that determines whether or not steam can be supplied to the steam turbine and the supply availability determination unit determine that supply is possible, the steam supply blocking unit transmits the steam from the second steam generation unit to the steam turbine. Circulated steam The steam supply shut-off unit is controlled such that the steam supply shut-off unit shuts off the steam from the second steam generation unit to the steam turbine when the supply availability determination unit determines that supply is not possible. A steam supply control unit that controls the shut-off unit, and the cooling water supply amount control unit controls the cooling unit to supply the cooling water when the supply availability determination unit determines that the supply is impossible. It is characterized by that.

  Further, a combined cycle power plant according to an aspect of the present invention is the above-described combined cycle power plant, wherein a steam turbine inlet pressure acquisition unit that acquires an inlet pressure of the steam turbine and generation of the second steam generation unit A steam pressure acquisition unit that acquires the pressure of the steam to be generated, a steam pressure adjustment unit that adjusts the pressure of the steam that the first steam generation unit supplies to the steam turbine, and the first steam generation unit that is the steam turbine Steam is supplied to the steam turbine, the steam supply shut-off unit shuts off steam from the second steam generation unit to the steam turbine, and an inlet pressure of the steam turbine is set to be equal to that of the second steam generation unit. Steam pressure for controlling the steam pressure adjusting unit to depressurize the steam supplied to the steam turbine by the first steam generating unit when the pressure is higher than the pressure of the generated steam. Characterized by comprising a control unit, a.

The control device according to one aspect of the present invention includes a first steam generation unit that generates steam from the exhaust gas of the first gas turbine, a second gas turbine, and the exhaust gas of the second gas turbine. A second steam generation unit to be generated, a steam turbine, a first pipe connecting the first steam generation unit and the steam turbine, and a connection between the second steam generation unit and the steam turbine. A second piping, a cooling section for supplying cooling water to the first piping, a turbine inlet temperature acquisition section for acquiring an inlet temperature of the steam turbine, and a steam temperature generated by the second steam generation section And a steam supply shut-off unit that shuts off steam from the second steam generation unit to the steam turbine, the control unit for a combined cycle power plant, wherein the first steam Generation Supplies steam to the steam turbine, the steam supply shut-off unit shuts off steam from the second steam generation unit to the steam turbine, and an inlet temperature of the steam turbine is the second temperature Based on the inlet temperature of the steam turbine and the temperature of the steam generated by the second steam generator when the temperature is higher than the temperature of the steam generated by the steam generator, the second steam generator When the supply availability determination unit that determines whether steam can be supplied to the steam turbine and the supply availability determination unit determine that supply is possible, the steam supply blocking unit causes the steam from the second steam generation unit to steam to the steam turbine. The steam supply shut-off unit is controlled to circulate, and the steam supply shut-off unit shuts off the steam from the second steam generation unit to the steam turbine when the supply availability determination unit determines that the supply is impossible. A steam supply control unit for controlling the serial steam supply interrupting unit, the supply judging unit may comprise determines that the Call supply, a cooling water supply amount control unit for controlling the cooling unit to supply the cooling water, the It is characterized by that.

  According to the present invention, a larger amount of steam can be supplied to the steam turbine from the newly started HRSG at an earlier stage, and adverse effects due to thermal stress in the steam turbine can be avoided.

It is a figure which shows main steam piping of the combined cycle power plant in one Embodiment of this invention. In the same embodiment, it is a graph which shows the example of the timing which a high pressure drum supplies steam to a high pressure steam turbine. In the same embodiment, it is a flowchart which shows the process sequence of a control apparatus at the time of starting supply of the vapor | steam from the HRSG activated later to a steam turbine. It is a figure which shows main steam piping of the combined cycle power plant in the modification of this invention. In the modification, it is a graph which shows the example of the timing which a high pressure drum supplies steam to a high pressure steam turbine. It is a figure which shows the example of main steam piping of the conventional combined cycle power plant. It is a graph which shows the example of the steam supply start timing from a high pressure drum to a high pressure steam turbine in the conventional combined cycle power plant.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing main steam piping of a combined cycle power plant in one embodiment of the present invention. In the figure, a combined cycle power plant 1 includes a gas turbine (first gas turbine) 11, a gas turbine (second gas turbine) 12, an HRSG (first steam generator) 21, and an HRSG (first gas turbine). 2 steam generator) 22, high-pressure steam turbine (steam turbine) 31, intermediate-pressure steam turbine 32, low-pressure steam turbine 33, generator 41, governor valves 51-56, bypass valves 61-65, , Condensers 71 and 72, spray valve 81, cooling water system 82, and controller 83. The HRSG 21 includes a high pressure drum 211, an intermediate pressure drum 212, and a low pressure drum 213. The HRSG 22 includes a high pressure drum 221, an intermediate pressure drum 222, and a low pressure drum 223. The control device 83 includes a cooling water supply amount control unit 831, a supply availability determination unit 832, and a steam supply control unit 833.
Moreover, the high pressure drum 211 and the high pressure steam turbine 31 are connected by piping P11 and P13, and the governor valve 51 is installed in the piping P11. The pipes P11 and P13 are examples of the first pipe. The high pressure drum 221 and the high pressure steam turbine 31 are connected by pipes P12 and P13, and a governor valve 52 is installed in the pipe P12. The pipes P12 and P13 are examples of the second pipe.

The gas turbine 11 is coupled to a gas turbine generator and a rotor. The gas turbine 11 is supplied with fuel and combusts it to generate combustion gas, and rotationally drives the combustion gas as working gas. By this rotational drive, the gas turbine generator rotates to generate power. Further, the gas turbine 11 outputs high-temperature exhaust gas, which is combustion gas after being used for rotational driving, to the HRSG 21.
Similarly, the gas turbine 12 outputs high-temperature exhaust gas to the HRSG 22.

The HRSG 21 generates steam in the high-pressure drum 211, the intermediate-pressure drum 212, and the low-pressure drum 213 by the exhaust gas from the gas turbine 11. The high pressure drum 211 generates steam to be supplied to the high pressure steam turbine 31, the intermediate pressure drum 212 generates steam to be supplied to the intermediate pressure steam turbine 32, and the low pressure drum 213 is supplied to the low pressure steam turbine 33. Produce steam for supply.
Similarly, the HRSG 22 uses the heat of the exhaust gas from the gas turbine 12 to generate steam in the high-pressure drum 221, the intermediate-pressure drum 222, and the low-pressure drum 223. The high pressure drum 221 generates steam to be supplied to the high pressure steam turbine 31, the intermediate pressure drum 222 generates steam to be supplied to the intermediate pressure steam turbine 32, and the low pressure drum 223 is supplied to the low pressure steam turbine 33. Produce steam for supply.

The high pressure steam turbine 31 is rotationally driven by steam supplied from the high pressure drums 211 and 221. The intermediate pressure steam turbine 32 is rotationally driven by the steam supplied from the intermediate pressure drums 212 and 222. The low pressure steam turbine 33 is rotationally driven by steam supplied from the low pressure drums 213 and 223.
The generator 41 is rotated by the high pressure steam turbine 31, the intermediate pressure steam turbine 32, and the low pressure steam turbine 33 to generate electric power.

The governor valve 51 is a flow rate adjustment valve installed in the pipe P <b> 11 between the high pressure drum 211 and the high pressure steam turbine 31, and adjusts the amount of steam that the high pressure drum 211 supplies to the high pressure steam turbine 31. The governor valve 52 is a flow rate adjustment valve installed in the pipe P <b> 12 between the high pressure drum 221 and the high pressure steam turbine 31, and adjusts the amount of steam that the high pressure drum 221 supplies to the high pressure steam turbine 31.
The governor valve 53 is a flow rate adjustment valve installed in a pipe between the intermediate pressure drum 212 and the intermediate pressure steam turbine 32, and adjusts the amount of steam that the intermediate pressure drum 212 supplies to the intermediate pressure steam turbine 32. The governor valve 54 is a flow rate adjustment valve installed in a pipe between the intermediate pressure drum 222 and the intermediate pressure steam turbine 32, and adjusts the amount of steam that the intermediate pressure drum 222 supplies to the intermediate pressure steam turbine 32.
The governor valve 55 is a flow rate adjustment valve installed in a pipe between the low pressure drum 213 and the low pressure steam turbine 33, and adjusts the amount of steam that the low pressure drum 213 supplies to the low pressure steam turbine 33. The governor valve 56 is a flow rate adjusting valve installed in a pipe between the low pressure drum 223 and the low pressure steam turbine 33, and adjusts the amount of steam that the low pressure drum 223 supplies to the low pressure steam turbine 33.

The bypass valve 61 is a pressure control valve installed between the high-pressure side pipe (pipes P11 to P13) and the medium-pressure side pipe, and bypasses part of the steam generated by the high-pressure drum 211 or the high-pressure drum 221 to the medium-pressure side. To do.
The bypass valve 62 is a pressure control valve installed between the intermediate pressure side pipe and the condenser 71, and bypasses a part of the steam generated by the intermediate pressure drum 212 to the condenser 71. The bypass valve 63 is a pressure control valve installed between the intermediate pressure side pipe and the condenser 71, and bypasses a part of the steam generated by the intermediate pressure drum 222 to the condenser 71.
The bypass valve 64 is a pressure control valve installed between the low pressure side pipe and the condenser 72, and bypasses part of the steam generated by the low pressure drum 213 to the condenser 72. The bypass valve 65 is a pressure control valve installed between the low pressure side pipe and the condenser 72, and bypasses a part of the steam generated by the low pressure drum 223 to the condenser 72.

  Condensers 71 and 72 cool the steam back to water. In particular, the condenser 71 returns the steam bypassed from the intermediate pressure drum 212 when the bypass valve 62 is opened and the steam bypassed from the intermediate pressure drum 222 when the bypass valve 63 is opened to water. The condenser 72 returns the steam bypassed from the low pressure drum 213 when the bypass valve 64 is opened and the steam bypassed from the low pressure drum 223 when the bypass valve 65 is opened to water.

The cooling water system 82 supplies cooling water. The spray valve 81 supplies the cooling water supplied from the cooling water system 82 to the pipe P11. The cooling water system 82 and the spray valve 81 constitute an example of a cooling unit, and the temperature of the steam supplied from the high pressure drum 211 to the high pressure steam turbine 31 is lowered by supplying the cooling water to the pipe P11.
The control device 83 controls each part of the combined cycle power plant 1. The control device 83 also controls each part other than the high-pressure drum 221 and the governor valve 52, but the illustration is omitted for easy understanding of the drawing.
Based on the inlet temperature of the high-pressure steam turbine 31 and the steam temperature of the high-pressure drum 221, the supply availability determination unit 832 determines whether steam can be supplied from the high-pressure drum 221 to the high-pressure steam turbine 31.

The cooling water supply amount control unit 831 controls the opening amount of the spray valve 81 according to the steam generated by the high-pressure drum 221, thereby reducing the amount of cooling water supplied by the cooling water system 82 and the spray valve 81 to the pipe P <b> 11. Control. Specifically, when the supply availability determination unit 832 determines that supply is not possible, the cooling water supply amount control unit 831 controls the spray valve 81 to open and supplies cooling water to the pipe P11.
When the supply availability determination unit 832 determines that the supply is possible, the steam supply control unit 833 controls the governor valve 52 to open and causes the steam to flow from the high pressure drum 221 to the high pressure steam turbine 31. On the other hand, when the supply availability determination unit 832 determines that supply is not possible, the steam supply control unit 833 controls the governor valve 52 to be closed to block the steam from the high pressure drum 221 to the high pressure steam turbine 31.

Next, the timing at which the high pressure drum 221 supplies steam to the high pressure steam turbine 31 will be described with reference to FIG.
FIG. 2 is a graph showing an example of timing at which the high-pressure drum 221 supplies steam to the high-pressure steam turbine 31 in the combined cycle power plant 1. In FIG. 4A, a line L111 indicates the inlet temperature of the high-pressure steam turbine 31, and a line L112 indicates the steam temperature of the high-pressure drum 221. Moreover, line L1011 shows the inlet temperature of the high pressure steam turbine in the conventional combined cycle power plant like the line L1011 of FIG. The steam temperature (line 1012 in FIG. 7) of the high-pressure drum in the conventional combined cycle power plant is the same as the line L112.

In the figure, the gas turbine 11 and the HRSG 21 have already been operating since time t11, and the high-pressure steam turbine 31 receives a supply of steam from the high-pressure drum 211 and has a constant inlet temperature. On the other hand, before the time t11, the gas turbine 12 and the HRSG 22 are stopped.
At time t11, the gas turbine 12 and the HRSG 22 are activated, and the steam temperature of the high-pressure drum 221 rises as indicated by a line L112. In the initial stage of startup, the steam temperature of the high-pressure drum 221 is significantly lower than the inlet temperature of the high-pressure steam turbine 31. Therefore, the control device 83 (steam supply control unit 833) causes the governor valve 52 to be fully closed so that the steam of the high-pressure steam drum 221 does not flow into the high-pressure steam turbine 31 and the turbine inlet temperature rapidly decreases. To control.
At time t12, the spray valve 81 opens under the control of the control device 83 (cooling water supply amount control unit 831), and supplies the cooling water from the cooling water system 82 to the pipe P11. Thereby, the temperature of the steam flowing through the pipe P11 is lowered, and the inlet temperature (line L111) of the high-pressure steam turbine 31 is gradually lowered.
At time t14, the steam temperature of the high-pressure drum 221 (line L112) reaches the inlet temperature (line L111) of the high-pressure steam turbine 31. Thus, the control unit 83 (steam supply control unit 833) controls the governor valve 52 to open without causing the high-pressure steam turbine 31 to be adversely affected by the thermal stress, so that the high-pressure drum 221 is connected to the high-pressure steam turbine 31. The supply of steam can be started.

At that time, the conventional method described in FIG. 6 and FIG. 7 or a new start-up in a state where there is a difference between the steam turbine inlet temperature described in Patent Document 1 and the steam temperature of the newly started HRSG. Compared with the method of preventing the stress level of the steam turbine from exceeding the predetermined stress limit value by adjusting the amount of steam fed from the HRSG to the steam turbine, the method of the present embodiment has an earlier stage. Thus, a larger amount of steam can be supplied from the high-pressure drum 221 to the high-pressure steam turbine 31.
That is, when the spray valve 81 supplies cooling water to the pipe P11, the turbine inlet temperature (line L111) of the high-pressure steam turbine 31 is lowered, and the steam temperature of the high-pressure drum 221 (line L112) is earlier than before. Reaches the turbine inlet temperature of the high-pressure steam turbine 31, so even if a larger amount of steam is supplied from the high-pressure drum 221 to the high-pressure steam turbine 31 at an earlier stage, the steam temperature of the high-pressure steam turbine 31 does not change. It is possible to avoid an adverse effect caused by the thermal stress of the steam turbine 31.

The supply of steam from the high pressure drum 221 increases the inlet steam flow rate (line L121) of the high pressure steam turbine 31 after time t14, thereby increasing the work amount of the high pressure steam turbine 31 (line L131).
Here, referring to FIG. 5C, during the period from time t12 to time t14, due to a decrease in the turbine inlet temperature (line L111) (a decrease in the temperature of the steam supplied from the high pressure drum 211), the high pressure steam turbine 31 The amount of work (line L131) is temporarily reduced. However, as described above, since more steam is supplied from the high-pressure drum 221 to the high-pressure steam turbine 31 at an earlier stage than the conventional method, as a whole (total in the time direction), more work is performed. The quantity can be obtained. That is, the generator 41 can generate a larger amount of power.

Next, processing performed by the control device 83 will be described with reference to FIG.
FIG. 3 is a flowchart showing a processing procedure of the control device 83 when starting supply of steam from the HRSG activated later to the steam turbine.
At the start of the process shown in the figure, steam is supplied to the high-pressure steam turbine 31 from the high-pressure drum 211 of the already operating HRSG 21 (step S101).

In this state, the control device 83 activates the gas turbine 12 that is a gas turbine that is activated later, and the HRSG 22 that is an HRSG that is activated later. Thereby, steam is generated in the HRSG 22 (step S102).
Next, the control device 83 controls the governor valve (the governor valve 52, the governor valve 54, and the governor valve 56) and the bypass valve (the bypass valve 61, the bypass valve 63, and the bypass valve 65) of the HRSG 22 that is an HRSG activated later. ) Is controlled (step S103). In particular, at this stage, the difference between the steam temperature of the high-pressure drum 221 and the inlet temperature of the high-pressure steam turbine 31 is large, and the control device 83 (steam supply control unit 833) determines the steam temperature of the high-pressure drum 221 and the inlet of the high-pressure steam turbine 31. Based on the temperature, the governor valve 52 is controlled to be fully closed.

Then, the control device 83 sets the control target value by calculating the change over time of the steam condition until the supply of steam from the high-pressure drum 221 to the high-pressure steam turbine 31 is started (step S104).
For example, the control device 83 determines the output of the gas turbine 11 and the gas turbine 12 and the output set value, the steam temperature of the high-pressure drum 211 and the high-pressure drum 221, the turbine inlet temperature of the high-pressure steam turbine 31, etc. The target value of the turbine inlet temperature change rate of the turbine 31 and the target value of the temperature change rate of the high-pressure drum 221 are stored in advance. And the control apparatus 83 selects the target value in which conditions match the state of the present plant based on the present various measured values and setting values in the combined cycle power plant 1, and makes it a control target value.

Next, the control device 83 calculates the maximum predicted stress of the high-pressure steam turbine 31 (the maximum value of thermal stress predicted in the blades, rotor, and the like of the high-pressure steam turbine 31) based on the control target value set in step S104. Calculate (step S105).
Then, based on the maximum predicted stress calculated in step S105, the control device 83 (supply availability determination unit 832) determines whether or not the steam of the high-pressure drum 221 activated later can be mixed (the steam of the high-pressure drum 221 is high-pressure). It is determined whether it is possible to mix with the steam of the drum 211 and supply it to the high-pressure steam turbine 31 (step S106). For example, in step S105, the control device 83 calculates the maximum predicted stress when the governor valve 52 is fully opened at the current time, and determines that mixing is possible if the calculated maximum predicted stress is equal to or less than the allowable thermal stress. If it is greater than the applied thermal stress, it is determined that mixing is not possible.

When it is determined that mixing is not possible (step S106: NO), the control device 83 (cooling water supply amount control unit 831) controls the spray valve 81 to open to lower the inlet temperature of the high-pressure steam turbine 31 (step). S111). The opening degree of the spray valve 81 is controlled by, for example, PID control. In addition, the control device 83 (steam supply control unit 833) controls the governor valve 52 to be fully closed.
Thereafter, the process returns to step S104.
On the other hand, when it determines with mixing possible in step S106 (step S106: YES), the control apparatus 83 calculates the opening degree of each valve (step S121), and controls each valve based on the calculated opening degree (step S121). S122). In particular, the control device 83 (steam supply control unit 833) controls to open the governor valve 52 so that the high-pressure drum 221 supplies steam to the high-pressure steam turbine 31. Further, the spray valve 81 is controlled to be fully closed, and the supply of the cooling water to the pipe P11 is ended.

  As described above, the cooling water supply amount control unit 831 controls the opening degree of the spray valve 81 to supply the cooling water to the pipe P11 and lower the inlet temperature of the high-pressure steam turbine 31 at an earlier stage. The steam temperature of the high-pressure drum 221 reaches the inlet temperature of the high-pressure steam turbine 31. Therefore, a larger amount of steam can be supplied from the high-pressure drum 221 to the high-pressure steam turbine 31 at an earlier stage, and adverse effects due to thermal stress in the high-pressure steam turbine 31 can be avoided.

  Further, the supply availability determination unit 832 determines whether steam can be supplied from the high pressure drum 221 to the high pressure steam turbine 31 based on the inlet temperature of the high pressure steam turbine 31 and the steam temperature of the high pressure drum 221, and the determination result On the basis of the above, the cooling water supply amount control unit 831 and the steam supply control unit 833 control the spray valve 81 and the governor valve 52, respectively, and automatically control the high pressure drum 221 to the high pressure steam turbine 31. A larger amount of steam can be supplied at an earlier stage, and adverse effects due to thermal stress in the high-pressure steam turbine 31 can be avoided.

  In the above description, the case where the gas turbine 12 and the HRSG 22 are newly started in a state where the gas turbine 11 and the HRSG 21 are already operating has been described. However, the combined cycle power generation is also possible when starting in the reverse order. The plant 1 may perform the same processing. Specifically, the combined cycle power plant 1 includes a cooling unit similar to the cooling water system 82 and the spray valve 81 between the high-pressure drum 221 and the governor valve 52. It comprises. When the gas turbine 12 and the HRSG 22 are already in operation and the gas turbine 11 and the HRSG 21 are activated later, the cooling water supply amount control unit 831 controls the spray valve of the cooling unit, Cooling water from the cooling water system is supplied to the pipe P12. Thereby, the inlet temperature of the high-pressure steam turbine 31 can be lowered. Therefore, as described above, a larger amount of steam can be supplied from the high-pressure drum 211 to the high-pressure steam turbine 31 at an earlier stage, and adverse effects due to thermal stress in the high-pressure steam turbine 31 can be avoided.

In the above description, the case where the inlet temperature of the high-pressure steam turbine 31 is lowered has been described. However, the same control can be performed for the intermediate-pressure steam turbine 32 and the low-pressure steam turbine 33.
Further, the number of gas turbines included in the combined cycle power plant 1 is not limited to the two described above, and may be three or more.

The control device may perform turbine inlet pressure control in addition to temperature control of the turbine inlet temperature.
FIG. 4 is a diagram showing main steam piping of a combined cycle power plant according to a modification of the present invention. In the figure, the same reference numerals (11, 12, 21, 211 to 213, 22, 221-223, 31 to 33, 41, 51 to 56, 61 to the parts having the same functions as those in FIG. 65, 71, 72, 81, 82, 831, 832, and 833), and description thereof is omitted.
The combined cycle power plant 2 includes a bypass valve 66 in addition to the components included in the combined cycle power plant 1 (FIG. 1), and the control device 89 includes a steam pressure control unit 894.

The bypass valve 66 is a pressure control valve installed between the high-pressure side pipe (pipe P11) and the medium-pressure side pipe, and bypasses part of the steam generated by the high-pressure drum 211 to the medium-pressure side. Thereby, the vapor | steam which flows through high pressure piping (piping P11) is pressure-reduced.
In the steam pressure control unit 894, the high pressure drum 211 supplies steam to the high pressure steam turbine 31, the governor valve 52 shuts off the steam from the high pressure drum 221 to the high pressure steam turbine 31, and the high pressure steam turbine. When the inlet pressure of 31 is higher than the pressure of the steam generated by the high-pressure drum 221, the bypass valve 66 is controlled so that the steam supplied from the high-pressure drum 211 to the high-pressure steam turbine 31 is reduced.

  FIG. 5 is a graph showing an example of timing at which the high-pressure drum 221 supplies steam to the high-pressure steam turbine 31 in the combined cycle power plant 2. In FIG. 6A, a line L211 indicates the inlet temperature of the high-pressure steam turbine 31, and a line L212 indicates the steam temperature of the high-pressure drum 221. Moreover, line L1011 shows the inlet temperature of the high pressure steam turbine in the conventional combined cycle power plant like the line L1011 of FIG. The steam temperature of the high-pressure drum (line 1012 in FIG. 7) in the conventional combined cycle power plant is the same as the line L212.

In the same figure, as in FIG. 2, the gas turbine 11 and the HRSG 21 have already been operating from before the time t11, and the high pressure steam turbine 31 receives the supply of steam from the high pressure drum 211 and maintains a constant inlet temperature. Have. On the other hand, before the time t11, the gas turbine 12 and the HRSG 22 are stopped.
At time t11, the gas turbine 12 and the HRSG 22 are activated, and the steam temperature of the high-pressure drum 221 increases as indicated by a line L212. As in the case of FIG. 2, the steam temperature of the high-pressure drum 221 is significantly lower than the inlet temperature of the high-pressure steam turbine 31, and the control device 83 (steam supply control unit 833) has the governor valve 52 in the initial stage of startup. Control to be fully closed.
At time t22, the spray valve 81 opens under the control of the control device 83 (cooling water supply amount control unit 831), and supplies the cooling water from the cooling water system 82 to the pipe P11. Thereby, the temperature of the steam flowing through the pipe P11 is lowered, and the inlet temperature (line L211) of the high-pressure steam turbine 31 is gradually lowered.
Further, at time t23, the bypass valve 66 opens according to the control of the control device 83 (steam pressure control unit 894), and bypasses a part of the steam from the high pressure drum 211 flowing through the pipe P11 to the intermediate pressure side. As a result, the steam supplied from the high-pressure drum 211 to the high-pressure steam turbine 31 is decompressed. For example, in step S104 in FIG. 3, the pressure reduction is performed by the control device 89 also setting a target value related to the turbine inlet pressure, and in step S111, the steam pressure control unit 894 controls the bypass valve according to the set target value. By doing. The bypass valve is controlled by, for example, PID control.

Thereafter, at time t24, the steam temperature of the high-pressure drum 221 (line L212) reaches the inlet temperature (line L211) of the high-pressure steam turbine 31. Thus, the high pressure steam turbine 31 can be opened from the high pressure drum 221 to the high pressure steam turbine 31 without opening the governor valve 51 without being adversely affected by the thermal stress.
Moreover, when the steam supply control unit 833 performs pressure control, when the supply of steam from the high-pressure drum 221 to the high-pressure steam turbine 31 is started, a rapid change in the inlet pressure of the high-pressure steam turbine 31 can be avoided.
Here, the rapid change in the turbine inlet pressure, like the temperature change, applies pressure to the blades and rotors of the turbine, and may have adverse effects such as shortening the life of the turbine blades and rotor. Therefore, by performing the above-described control, the combined cycle power plant 2 can avoid an abrupt change in turbine inlet pressure and avoid adverse effects on turbine blades, rotors, and the like.

  5B and 5C, the inlet flow rate of the high-pressure steam turbine 31 increases from time t24 (line L221), thereby increasing the amount of work of the high-pressure steam turbine 31. As described above, as in the case of FIG. 2, the work amount of the high-pressure steam turbine 31 increases at an earlier stage, and as a whole (total in the time direction), a larger work amount can be obtained.

A program for realizing all or part of the functions of the control device 83 or 89 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. You may process each part by. Here, the “computer system” includes an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention.

1, 2 Combined cycle power plant 11, 12 Gas turbine 21, 22 HRSG
211, 221 High pressure drum 212, 222 Medium pressure drum 213, 223 Low pressure drum 31 High pressure steam turbine 32 Medium pressure steam turbine 33 Low pressure steam turbine 41 Generator 51-56 Governor valve 61-65 Bypass valve 71, 72 Condenser 81 Spray Valve 82 Cooling water system 83, 89 Control device 831 Cooling water supply amount control unit 832 Supply availability determination unit 833 Steam supply control unit 894 Steam pressure control unit

Claims (3)

A first gas turbine;
A first steam generation unit that generates steam from the exhaust gas of the first gas turbine;
A second gas turbine;
A second steam generation unit that generates steam from the exhaust gas of the second gas turbine;
A steam turbine;
A first pipe connecting the first steam generation unit and the steam turbine;
A second pipe connecting the second steam generation unit and the steam turbine;
A cooling unit for supplying cooling water to the first pipe;
A cooling water supply amount control unit that controls the amount of cooling water supplied to the first pipe by the cooling unit in accordance with the steam generated by the second steam generation unit;
A turbine inlet temperature acquisition unit for acquiring an inlet temperature of the steam turbine;
A steam temperature acquisition unit for acquiring a temperature of the steam generated by the second steam generation unit;
A steam supply blocking unit that blocks steam from the second steam generation unit to the steam turbine;
The first steam generation unit supplies steam to the steam turbine, the steam supply blocking unit blocks steam from the second steam generation unit to the steam turbine, and an inlet of the steam turbine When the temperature is higher than the temperature of the steam generated by the second steam generation unit, based on the inlet temperature of the steam turbine and the temperature of the steam generated by the second steam generation unit, the first A supply availability determination unit that determines whether steam can be supplied from the steam generation unit of 2 to the steam turbine;
When the supply availability determination unit determines that supply is possible, the steam supply cutoff unit controls the steam supply cutoff unit so that the steam from the second steam generation unit flows to the steam turbine, and the supply availability determination unit Determines that the supply is impossible, a steam supply control unit that controls the steam supply blocking unit so that the steam supply blocking unit blocks the steam from the second steam generation unit to the steam turbine;
Comprising
The combined cycle power plant, wherein the cooling water supply amount control unit controls the cooling unit to supply the cooling water when the supply availability determination unit determines that supply is not possible . A steam turbine inlet pressure acquisition unit for acquiring the inlet pressure of the steam turbine;
A steam pressure acquisition unit for acquiring the pressure of the steam generated by the second steam generation unit;
A steam pressure adjusting unit for adjusting a pressure of steam supplied from the first steam generating unit to the steam turbine;
The first steam generation unit supplies steam to the steam turbine, the steam supply blocking unit blocks steam from the second steam generation unit to the steam turbine, and an inlet of the steam turbine Steam for controlling the steam pressure adjusting unit so as to depressurize the steam supplied to the steam turbine by the first steam generating unit when the pressure is higher than the pressure of the steam generated by the second steam generating unit. A pressure control unit;
The combined cycle power plant according to claim 1, comprising: A first steam generation unit that generates steam from the exhaust gas of the first gas turbine;
A second gas turbine;
A second steam generation unit that generates steam from the exhaust gas of the second gas turbine;
A steam turbine;
A first pipe connecting the first steam generation unit and the steam turbine;
A second pipe connecting the second steam generation unit and the steam turbine;
A cooling unit for supplying cooling water to the first pipe;
A turbine inlet temperature acquisition unit for acquiring an inlet temperature of the steam turbine;
A steam temperature acquisition unit for acquiring a temperature of the steam generated by the second steam generation unit;
A steam supply blocking unit that blocks steam from the second steam generation unit to the steam turbine;
A combined cycle power plant control device comprising:
The first steam generation unit supplies steam to the steam turbine, the steam supply blocking unit blocks steam from the second steam generation unit to the steam turbine, and an inlet of the steam turbine When the temperature is higher than the temperature of the steam generated by the second steam generation unit, based on the inlet temperature of the steam turbine and the temperature of the steam generated by the second steam generation unit, the first A supply availability determination unit that determines whether steam can be supplied from the steam generation unit of 2 to the steam turbine;
When the supply availability determination unit determines that supply is possible, the steam supply cutoff unit controls the steam supply cutoff unit so that the steam from the second steam generation unit flows to the steam turbine, and the supply availability determination unit Determines that the supply is impossible, a steam supply control unit that controls the steam supply blocking unit so that the steam supply blocking unit blocks the steam from the second steam generation unit to the steam turbine;
A cooling water supply amount control unit that controls the cooling unit to supply the cooling water when the supply availability determination unit determines that the supply is impossible;
A control device comprising:

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