JPH04103808A - Compound power generating plant and operating method thereof - Google Patents

Abstract

PURPOSE:To supply a load from a central load dispatching office without waiting completion of start by making starting operation on the basis of a preset load, and receiving the load setting from the central load dispatching office under restriction before completion of start of a steam turbine. CONSTITUTION:When a gas turbine 22 is started and a turbine load reaches 50%, a high pressure regulating valve 26a is opened gradually. Till this time, operation is carried out under a load which is set by a unit load setting part 9. When the high pressure regulating valve 26a is opened, a switching part 3 is switched to operate in compliance with a load command 10 outputted from a central load dispatching office 1. After that, when the high pressure regulating valve 26a and a low pressure regulating valve 26b are full opened, a starting completion mode is achieved. A specified load changing rate is selected in the load changing rate setting part 5 and increasing/decreasing change of the load can be carried out in the central load dispatching office 1. It is thus possible to supply the load from the central load dispatching office 1 without waiting completion of start.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a combined power generation plant, and particularly to a combined power generation plant and a combined power generation plant that can contribute to power system operation even during startup and that can continue smooth startup operations. Regarding its driving method.

[Prior Art] A combined cycle power plant includes a gas turbine, an exhaust heat recovery boiler, and a steam turbine as main components.

As shown in FIG. 3, the standard method for starting a combined power generation plant is to first start up the gas turbine, increase its speed, and perform purge for a certain period of time. After that, it is ignited, and if there is residual pressure in the waste heat recovery boiler, the shaft is immediately sped up to the rated speed as shown in the figure.

Paralleling of the shafts is achieved by a gas turbine. When the steam turbine is hot, as shown in FIG. 3, even when the turbines are parallel, the control valve is not opened, and cooling steam is only secured on the low pressure side. The steam turbine is
In this state, the gas turbine load increases, and ventilation is performed after the gas turbine outlet exhaust gas temperature and main steam temperature rise accordingly. In FIG. 3, when the gas turbine load is 50%, the steam turbine is just waiting for ventilation.

Based on the relationship between the output of the gas turbine, which is the main engine of a combined cycle power plant, and the exhaust gas temperature, the exhaust heat recovery boiler and steam turbine have the characteristics that the output and temperature change depending on the gas turbine load, as shown in Figure 2. This characterizes the operation of combined cycle power plants. The point indicated as steam turbine ventilation in FIG. 3 indicates the point where the main steam temperature increases as the gas turbine load increases, and the temperature difference from the turbine metal temperature falls within the permissible value for ventilation. After venting, the steam turbine control valve opens toward full opening at a rate that does not affect the process. At the same time as the control valve opens, the turbine bypass valve, which was previously releasing steam generated from the heat recovery boiler to the condenser, closes.

After venting, the steam turbine metal temperature changes with the main steam temperature.

Here, I would like to add some information about the thermal stress and life consumption of steam turbines.

Thermal stress in a steam turbine is caused by the temperature difference between the surface and the inside of the turbine rotor in the radial direction.When a temperature change occurs between the surface of the turbine rotor and the fluid in contact with it, Thermal stress occurs due to the temperature difference between the

The life of a steam turbine rotor is consumed by large thermal stresses associated with startup, shutdown, large load changes, and the like. The value of thermal stress per cycle is determined once the starting procedure, stopping procedure, load change rate, and change width are determined. Long-term operation for each plant, i.e. startup at the end of the rotor's service life;
By specifying the stop circuit and the number of significant load changes, the life consumption rate per time can be determined. Now count backwards and start.
The upper limit of the maximum thermal stress value per stop and significant load change is determined.

Unless the operation is changed, it is common practice to adjust the startup and shutdown procedures to shorten startup and shutdown times and improve the load change rate within a range that does not exceed the upper limit of the maximum thermal stress value.

In conventional thermal power plants, the boiler that generates steam controls the main steam temperature to be constant. Therefore, the main cause of thermal stress is that the rate of temperature drop due to the restriction of the steam regulator valve at the inlet of the steam turbine increases or decreases in response to changes in the opening of the regulator valve during startup or load changes.

On the other hand, in a combined cycle power plant, the main steam output is low and the rate of temperature drop due to throttling is small.

However, as shown in Figure 2, the main steam temperature itself is
Due to the characteristics of gas turbine exhaust gas temperature, it changes greatly depending on the load.

In order to suppress the occurrence of thermal stress, it is necessary to reduce the range of change in main steam temperature or the rate of temperature change.

During startup, when the load change range is large, the main steam temperature change range is large, so it is necessary to suppress the change rate of the main steam temperature to a lower level. Therefore, it is necessary to suppress the change in the exhaust gas temperature at the gas turbine outlet, which is the source of the main steam temperature change, that is, the change in the gas turbine load. For this reason, in the combined power generation plant, the gas turbine load rate is rapidly lowered after one ventilation, as shown in FIG.

The figure shows an example of a mixed pressure type steam cycle of high pressure and low pressure, and shows a situation where the low pressure regulator opens while the high pressure regulator is opening. When both the high pressure and low pressure control valves are fully open,
The combined cycle power plant has started up, and the control valve remains fully open.
Load control is carried out by adjusting the gas turbine's fuel, and the steam turbine enters normal operation of the combined cycle power plant by simply swallowing the generated steam.

The conventional operating method is that the single unit capacity of a combined cycle power plant is smaller than that of a steam power plant due to gas turbine capacity constraints, and that the gas turbine load must be increased at the load change rate at startup until the control valve is fully opened. Due to these constraints, we have adopted a method of leaving the load on the starting plant to its own discretion until the start-up is complete, and then handing over the load to the intermediate plant once the start-up is complete.

Here, we will provide a brief supplementary explanation of the operation of the power supply system.

(Central power dispatch control center that supervises the power supply system (hereinafter referred to as "Central dispatch center"))
Now, while balancing demand and supply, we will consider how efficiently and stable power can be provided to consumers, and perform load adjustment, including starting and stopping each power generation plant that makes up the power source. Since electricity is generated and consumed instantaneously, we ensure that we have enough power generation equipment to supply electricity throughout the year, and balance supply and demand by adjusting the amount of electricity generated according to demand.

Power generation equipment as a power source can be divided into nuclear power, thermal power, hydropower, etc. depending on how the energy source is obtained.

In terms of system operation, nuclear power is generally divided into base load operation and thermal power is divided into intermediate load operation. Specifically, during times of low demand such as nights and weekends.

Nuclear power plants carry most of the load, increasing the load on large-scale power plants as demand increases during the day, and lowering the load on thermal power plants as demand decreases during the night, shifting to partial load operation or shutdown.

The efficiency of a thermal power plant decreases as the load decreases at partial load, and it is often economically advantageous to shut down power generation rather than continue generating power at low load.

However, there are limitations such as the complexity of various operating operations associated with stopping and starting, and the inability to meet intermediate load requests until starting is completed.

From the perspective of the intermediate supply, it is desirable to have a power generation plant that can quickly stop and start up, and after starting up and paralleling, quickly adjust the output according to the load demand of the intermediate supply. A combined power generation plant requires a short start-up/stop time, and has good load response when normal operation begins after completion of start-up. Therefore, combined cycle power plants are expected to be very good power sources suitable for medium load operation in this respect.

However, the grid-handling load that can respond to intermediate supply load requests after startup is approximately one-fourth of the total load in conventional power generation plants, whereas in combined power generation plants, the grid-handover load that can respond to intermediate supply load requests is approximately one-fourth of the total load.
Although there are constraints on plant operation, during this period, the load request from the intermediate supply is not met, and the
This is an undesirable operation for mid-career workers, as they continue to carry out the burden of starting operations.

In addition, as a document related to the operation method of combined cycle power generation plants, “Thermal and Nuclear Power Generation J Vol.
38. "Nα12r Futtsu Thermal Power Plant No. 1 Series Operational Status" is mentioned.

[Problems to be Solved by the Invention] The above conventional technology is acceptable when the power system is large and the ratio of combined power generation plants is small. However, if the power system is not that large, the conventional method of waiting for startup to complete and not entering intermediate load operation until the high load range is not effective at starting up, but does not meet the power plant's mission of contributing to power system operation. It will be contrary. In particular, in view of the tendency for the capacity of a single combined cycle power plant to increase due to an increase in the capacity of gas turbines,
The challenge is to resolve this point.

An object of the present invention is to provide a combined power generation plant and a method for operating the same, in which intermediate load can be transferred without waiting for completion of startup.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a combined power generation plant that has a gas turbine and a steam turbine as power sources and generates power according to load settings from a central power supply station. 5. When starting the gas turbine and then starting the steam turbine, the starting operation is performed based on the preset load. The present invention is characterized in that it accepts a range that is smaller than the current state, performs operation, and after completion of startup, cancels the restriction and performs operation.

The above restrictions include, for example: (1) only load settings that result in a load increase are accepted; (2) the rate of change in load is a value smaller than the rate of change in load under normal operating conditions; (2) the load is determined in advance by the magnitude of thermal stress. If this value is exceeded, the load change rate may be set to a smaller value.

During startup, the timing for receiving the negative 'a setting from the central power supply station may be, for example, after the steam turbine is vented and before the overtime is completed. It is preferable to carry out the process immediately after venting the steam turbine.

According to one aspect of the present invention, one or more gas turbines, at least one exhaust heat recovery boiler that utilizes the exhaust heat of the gas turbine, and at least one steam turbine that uses the generated steam as a driving source. , and at least one generator driven by each or both of the gas turbine and the steam turbine, the combined power plant generates electricity according to the load settings from the central power supply station, means for setting load and load change rate in startup mode; means for determining whether or not to accept a load setting from a central power supply station after startup and before completion of startup; A combined power generation plant is provided that includes means for imposing a limit on load setting according to the state of the plant, and means for canceling the limit after completion of startup.

In addition, in a combined power generation plant that has a gas turbine and a steam turbine as power sources and generates power according to the load setting of the central power supply station, it is possible to and a gas turbine fuel f#IJ control device that controls the supply amount of the S charge based on the fuel increase/decrease command, and the load control device includes: The faUll mode has a normal operation mode and a start-up mode, and in the start-up mode, before the start-up of the steam turbine is completed, the load setting from the central power supply station is set to a fpJ limit of 1/JS smaller than the normal operation state. A combined power generation plant is provided, which has a function of receiving and operating the system, and a function of canceling the 1iIJ limit and returning to the normal operation mode after the start-up is completed.

[Operation] It is preferable for system operation to pass the load setting of the combined cycle power plant to the central power supply station as soon as possible. For this reason 1
The present invention performs a starting operation based on a preset load when starting a gas turbine and then starting a steam turbine.

Before the steam turbine is completely started, load settings from the central power supply station can be accepted with restrictions, and it is possible to partially contribute to the power operation of the grid without waiting for the start of the steam turbine to be completed.

By placing restrictions on load settings, the sudden decrease in main steam output caused by lowering the load on the gas turbine at the same time as the opening of the control valve and the excessive thermal stress caused by the drop in main steam temperature are suppressed. For example, if it is decided that only a load increase command is accepted as a restriction, a sudden decrease in main steam output can be avoided, and a drum level fluctuation of the exhaust heat recovery boiler due to a sudden decrease in output can be suppressed. This allows the stability of the plant to be maintained. Further, when a limit is imposed to suppress the load change rate to a small range, the thermal stress at the time of startup of the steam turbine can be kept within a predetermined value, and the life distribution of the steam turbine can be maintained.

For gas turbine loads where the ventilation conditions cannot be met before ventilation, by not accepting load reduction operations, the load will always increase until the control valve opens, allowing the startup operation to continue. be able to.

By adding a thermal stress control function, it is possible to start up the steam turbine without unduly increasing its life consumption due to transient thermal stress while increasing its contribution to power system operation. Note that the thermal stress control function here is a function that lowers the load change rate when the thermal stress value exceeds a set value.

Furthermore, when excluding the thermal stress control function at startup, by checking that the thermal stress value is below the allowable value, startup is completed while the thermal stress control is working and the load change rate is being reduced. The load change rate immediately switches to the value in the normal operation mode, and it is possible to prevent the thermal stress value from increasing again.

(Margins below) [Examples] Examples of the present invention will be described below with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS. 1 and 5.

The combined power generation plant of this embodiment includes a compressor 22a,
A gas turbine 22 having a combustor 22b and a turbine 22c, an exhaust heat recovery boiler 25 that utilizes the exhaust heat of the gas turbine 22, a turbine 24a and a condenser 24b.
It has a steam turbine 24 having a steam turbine 24, and a generator 23 driven by the gas turbine 22 and the steam turbine 24.

The combustor 22. A fuel control valve 21 that adjusts the amount of fuel supplied is connected to b.

The exhaust heat recovery boiler 25 generates high pressure steam and low pressure steam. These steams are supplied to the turbine 24a via the high pressure regulating valve 26a and the low pressure regulating valve 26b, respectively. In addition, exhaust heat recovery boiler 25 and condensate! ! 24b, a turbine bypass valve (not shown) is provided.

The combined power generation plant of this embodiment also includes a load control device 2 that generates a fuel increase/decrease command 14 and performs load control based on a load setting command from an intermediate supply 1 and information from the plant such as generator output. , and a gas turbine fuel control device 7 that controls a fuel control valve 21 based on a fuel increase/decrease command 14 output from the load control device 2.

The load control device 2 includes a unit load setting section 9 that sets the load and load change rate according to the state of the plant at startup and outputs a command 11, and a command 1 from the unit load setting section 9. a switching unit 3 that switches between the command 10 from the power supply 1 and the command 10 by referring to plant information indicating the state of the plant;
A load increase/decrease command unit 4 outputs a load increase/decrease command 13 based on the command 11 or 10 and plant information, and a load change command unit 4 sets a load change rate for the load increase/decrease command 13 according to the state of the plant to issue a fuel increase/decrease command 14. The load change rate setting section 5 outputs the load change rate.

These components can be configured in whole or in part by a computer system. For example, it can be configured by hardware such as a central processing unit (CPU), memory, various interfaces, and registers, and software stored in the memory and executed by the CPU.

For example, the software is shown in FIG. 1(C).

A program for executing processing as shown in FIG. 5(b) is included.

The load change rate setting section 5 is configured as shown in FIG. 5(a). That is, load change rate applying units 52, 53 and 54, which respectively give load change rates, a switch 55 that selects these load change rates, and a load that controls the switching operation of this switch 55 according to the state of the unit. It has a rate of change switching logic 51a and a rate of change limiter 56 that limits the rate of change of the load increase/decrease command 13 based on the load change rate selected by the switch 55 and outputs it as the fuel increase/decrease command 14. .

The load change rate set in this embodiment is the load change rate (a) when the unit is normally started in the load change rate giving section 52, and the load change rate (a) when the unit is starting up in the same 53 and the load setting is on the plant side. The load change rate (b) is set at 54, and the load change rate (c) when the unit is activated and the load setting is on the intermediate supply side is set.

The system composed of the hardware and software described above has a means for setting the load and load change rate in a predetermined startup mode at startup, and a means for setting the load in a predetermined startup mode and load change rate from the central power supply station after startup and before completion of startup. When there is a setting, it functions as a means for determining whether to accept it, a means for limiting the load change rate in response to acceptance of the load setting, and a means for canceling the restriction after completion of startup.

Note that all or part of the load control device 2 may be configured using a hard logic circuit.

In addition, although not shown in the figure, various parts of the plant include output sensors,
In addition to temperature sensors and the like, electric meters and the like that detect the generator output are arranged. Information from these sensors can be e.g.
converted into digital data and sent to the load control device 2,
It is supplied as plant information indicating the status of the plant.

Next, the operation of this embodiment will be explained with reference to the drawings.

As shown in FIG. 1, a load setting command 10 output from the intermediate supply 1 to the combined cycle power plant passes through the load control device 2 and is sent as a fuel increase/decrease command 14 to the gas turbine fuel control device 7. . During normal operation, the load on the power plant is controlled as described above, but at startup, the load is set according to the plant state at startup in order to limit the thermal stress of the steam turbine and stabilize the process. , load change rate settings are defined. Therefore, the switching unit 3
The load setting is made on the side of the unit load setting section 9 and separated from the intermediate feeder 1 to ensure stable startup.

In this embodiment, the switching timing from the command from the unit load setting section 9 to the intermediate supply load setting command 10 is brought forward. That is, in this embodiment, instead of switching at the timing shown in FIG. 1(b), the switching is performed at the timing shown in FIG. 1(c).

That is, in the flowchart of FIG. 1(b), when the intermediate worker l side selects the load setting after completion of startup, the load setting is passed to the intermediate worker side. On the other hand, Fig. 1(C)
In the present embodiment shown in , if the intermediate pay transfer condition is satisfied before the start-up is completed, the load setting intermediate pay transfer becomes possible. 1st
The conditions expressed as intermediate feed delivery conditions in Figure (C) indicate conditions that are essential for continued plant operation, such as minimum load or higher, or after steam turbine ventilation, for example.

To speed up the timing of switching load settings,
As shown in FIG. 5(a), even after setting the load change rate (c) in the load change rate setting section 5 and performing intermediate feeding, the load range signal will not be output if the unit is starting. That's what I do.

An example of the output of the load change rate setting section 5 is shown in FIG.

This shows elapsed time on the horizontal axis, with the upper side representing load increase.

The lower part is taken as the load range side, and the outermost line (a) shows the load change when the load change rate during normal operation is selected. In the figure, the line (c) shows the load change at the load change rate added to realize this embodiment.

FIG. 5(b) shows the flow for selecting the load change rate.

The load change rate logic 51a controls the switch 55 according to the flowchart shown in FIG. 5(b).

That is, first, it is determined whether or not the unit is in normal operation (step 501), and if it is in normal operation, the load change rate (
a) is selected (step 504).

If the unit is not in normal operation, it is determined whether it is starting up (step 502). If it is not started, step 5
Returns to 01. On the other hand, if it is starting, the load setting is medium pay 1.
It is determined whether it is the side (step 503). Here, middle salary 1
If not, load change rate (b) is selected (step 5
05), if it is on the intermediate pay 1 side, the load change rate (c) is selected (step 506).

In this way, since the load change rate is set according to the state of the plant, the fuel increase/decrease of the gas turbine is set with these load change rates as the limit.

That is, as shown in FIG. 4, the gas turbine 22 is started, the rotation speed reaches the rated speed, and the turbine load is reduced to 50%.
Until the steam turbine 24 is ventilated, the load change rate setting section 5 selects the load change rate (b). In the example shown in FIG. 4, it is set to 8.3%/MIN. When the load reaches 50%, after operating for a while in this state, the high pressure regulating valve 26a is gradually opened. Up to this point, the unit is operated with the load set by the unit load setting section 9.

When the high pressure regulating valve 26a is closed, the load setting is set to intermediate feed 1.
passed to. That is, the switching unit 3 is switched and operates according to the load command 10 from the intermediate feeder 1. In this state, the load change rate setting section 5 selects the load change rate (c) because it is the startup mode. In the example shown in Figure 4,
It is set to 3%/MIN.

After this, the low pressure regulating valve 26b is also opened, and the high pressure regulating valve 26a is opened.
, the low pressure regulating valve 26b is gradually opened to a limit of 2%/MIN. And both valves 26a.

26b is fully opened, the start-up completion mode is entered, and the load change rate setting section 5 selects the load change rate (a). As a result, the mid-career worker 1 can increase or decrease the load within the range of the load change rate (a).

In this way, by accelerating the transfer of the load from the intermediate supply, the unit continues to start up stably, suppressing the generation of excessive thermal stress, and responding to the load request from the intermediate supply, even if only in the direction of increase. It is possible to create a combined power generation plant that can meet the demand.

Next, a second embodiment of the present invention will be described using FIG. 6.

As shown in FIG. 6(a), this embodiment is configured by adding a load change rate applying section 57 to the load change rate setting section 5 of the first embodiment described above, and the rest is the same as that of the first embodiment. Same as example. Therefore, the differences will be mainly explained here.

FIG. 6(a) shows an example of the load change rate setting section 5 used in this embodiment.

The load change rate setting unit 5 shown in the figure includes load change rate giving units 52, 53, 54, and 57 that set load change rates, a switch 55 that selects these load change rates, and a switch 55 that selects these load change rates. A load change rate switching logic 51b that controls the switching operation according to the state of 22-1-, and a fuel increase/decrease by limiting the rate of change of the load increase/decrease command 13 based on the load change rate selected by the switch 55. The change rate limiter 56 outputs the command 14.

The load change rate switching logic 51b operates as shown in FIG. 6(b). Here, steps 501 to 506 are
This is the same as the flowchart shown in FIG. 5(b).

In this embodiment, it is determined whether or not the load range continues βMW (step 601), and if the load range continues, the load change rate (
c) is selected (step 506) and is not a continuation;
A load change rate (d) is selected (step 602).

As shown in FIG. 8, this load change rate (d) allows not only the load increase direction but also the load decrease direction.

The load reduction operation is performed at the time of startup, and a determination is made as to whether or not the load range continues βMV,7 so as not to reduce the load indefinitely. Here, the load range continuation βMW
However, of course, various limiting conditions are taken into account depending on the plant state, for example, the operation of the power plant, such as limiting the ventilation conditions of the steam turbine.

By speeding up the intermediate load transfer as described above,
Combined power generation that can respond to intermediate supply load requests in both increasing and decreasing directions without causing a sudden decrease in main steam output or generating excessive thermal stress, while continuing startup operations. It can be a plant.

Finally, a third embodiment of the present invention will be described using FIG. 7.

This embodiment is configured in the same manner as the first embodiment described above, except for a part of the load change rate setting section 5.

Therefore, the explanation will focus on the differences here.

FIG. 7(,) shows an example of a load change rate setting section used in this embodiment.

The load change rate setting unit 5 shown in the figure includes load change rate giving units 52, 53 and 58 that provide load change rates, a switch 55 that selects these load change rates, and a switching operation of this switch 55. A load change rate switching logic 51c that controls according to the state of the unit and a change rate that limits the change rate of the load increase/decrease command 13 based on the load change rate selected by the switch 55 and outputs it as the fuel increase/decrease command 14. Limiter 56
It has

The load change rate switching logic 51c operates as shown in FIG. 7(b). Here, steps 501 to 505 are
This is the same as the flowchart shown in FIG. 5(b).

In this embodiment, after the load setting is shifted to the intermediate supply side 1, it is determined whether the thermal stress is equal to or greater than a specified value (step 701). If it is not equal to or greater than the specified value, the load change rate (a) is selected (step 504). On the other hand, if it is equal to or greater than the specified value, the load change rate (e) is selected (step 702).

For the sake of simplicity, here, it is stated that the load change rate (a) during normal operation of the unit should be selected after intermediate supply load transfer even when the unit is started, but the load change rate (a) during unit normal operation is selected. An appropriate load change rate may be selected between the load change rate and the load change rate during normal operation of the unit.

If thermal stress exceeds a predetermined value during unit startup, a lower load change rate (e) is selected to suppress further generation of thermal stress.

In this way, by accelerating the intermediate feed load transfer, it is possible to create a combined power generation plant that is capable of operating the intermediate feed load equivalent to that during normal operation, even during startup, within a range where thermal stress does not become excessive.

Each embodiment of the present invention has been described above, but in actual application, these can be combined as appropriate to take a method suitable for the operation of each power plant.

According to each of the embodiments described above, in the past, in the case of a hot start, startup was not completed unless the load was extremely high, such as 80% to 90%, and intermediate load transfer was not possible. As shown in Figure 2, intermediate load transfer is possible in a low load range of 30 to 40%. Furthermore, since the start-up operation can be continued smoothly, the operability of the combined cycle power plant can be further improved. As a result, a power generation plant that is easy to use in terms of power system operation can be realized.

In addition, although each of the above-mentioned embodiments shows an example of a -axis type as shown in FIG. 1, the present invention is not limited to this type, and may be a multi-axis type. Furthermore, although these embodiments show examples of a mixed pressure type, a vehicle pressure type may also be used.

[Effects of the Invention] According to the present invention, there is an effect that intermediate supply load can be transferred without waiting for completion of startup. As a result, even if the capacity of the gas turbine increases and the capacity of a single combined cycle power plant increases, although there are restrictions on the load range, it can be incorporated into medium load operation from the low load range, and the power grid It can be expected to make a significant contribution to operations.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram showing the configuration of an embodiment of the combined power generation plant of the present invention, FIG. Figure (C) is a flowchart showing the timing of intermediate feeding for load settings in the operating method of one embodiment of the present invention, Figure 2 is a graph showing exhaust gas temperature characteristics and main steam characteristics with respect to gas turbine load, and Figure 3 is FIG. 4 is a graph showing the startup characteristics of a conventional combined cycle power plant, FIG. 4 is a graph showing the startup characteristics of a combined power plant according to an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram showing an example of the configuration of a load change rate setting section used in the configuration of the embodiment. FIG. 5(b) is a flowchart showing the processing procedure in the load change rate switching logic that constitutes the setting section in the figure, and FIG. 6(a) is the load change rate setting section used in the configuration of the second embodiment of the present invention. FIG. 6 (b) is a block diagram showing an example of the configuration of
) is a flowchart showing the processing flow of the load change rate switching logic that constitutes the circuit of the same figure, and FIG. 7(a) is an example of the configuration of the load change rate setting section used in the configuration of the third embodiment of the present invention. FIG. 7(b) is a flowchart showing the processing flow of the load change rate switching logic that constitutes the circuit in the same figure, and FIG. 8 is a block diagram showing the process set in the first to third embodiments described above. It is a graph which illustrates the magnitude|size of a load change rate. 1... Intermediate supply (central power supply station), 2... Load control device,
3... Switching unit, 4... Load increase/decrease command unit, 5... Load change rate setting unit, 7... Gas turbine fuel control device,
21...Fuel control valve, 22...Gas turbine, 22
a...Compressor, 22b...Combustor, 22c...
... Turbine, 23... Generator, 24... Steam turbine, 24a... Turbine, 24b... Condenser, 2
5...Exhaust heat recovery boiler, 26a...High pressure regulating valve, 2
6b...Low pressure regulating valve. Figure 1 (b) (c) Applicant: Hitachi, Ltd. Chugoku Electric Power Co., Ltd.

Claims (1)

[Claims] 1. In a combined power generation plant that has a gas turbine and a steam turbine as power sources and generates power according to load settings from a central power supply station, the gas turbine is started, and then the steam turbine is started. When starting up, a starting operation is performed based on a preset load, and before the steam turbine starts up, the load setting from the central power supply station is limited to a range smaller than the normal operating state, and the operation is started. 1. A method for operating a combined power generation plant, characterized in that after the start-up is completed, the restriction is canceled and the operation is performed. 2. The method of operating a combined power generation plant according to claim 1, wherein the restriction is such that only load settings that result in an increase in load are accepted. 3. Claim 1, wherein the restriction is to set the load change rate to a value smaller than the load change rate in normal operating conditions.
Or the method of operating a combined power generation plant according to 2. 4. The method of operating a combined power plant according to claim 1 or 3, wherein the restriction is such that the load change rate is reduced to a small value when the load exceeds a value predefined by the magnitude of thermal stress. . 5. The method of operating a combined power plant according to claim 1, 2, 3, or 4, wherein the load setting is received from the central power supply station after the steam turbine is ventilated and before the startup is completed. 6. One or more gas turbines, at least one exhaust heat recovery boiler that utilizes the exhaust heat of the gas turbine, at least one steam turbine that uses the generated steam as a driving source, and the gas turbine and the steam turbine. A combined power generation plant comprising at least one generator driven by each or both of the following, and which generates electricity according to the load setting from the central power supply station, which at the time of start-up, sets the load in a predetermined starting mode and means for setting a load change rate; means for determining whether or not to accept a load setting from a central power supply station after startup and before completion of startup; 1. A combined power generation plant, comprising: means for applying a restriction according to the state of the power generation plant; and means for canceling the restriction after completion of startup. 7. In a combined power generation plant that has a gas turbine and a steam turbine as power sources and generates power according to the load settings from the central power supply station, based on the load settings from the central power supply station and information representing the plant status. and a gas turbine fuel control device that controls the supply amount of the fuel based on the fuel increase/decrease command, and the load control device has a control mode in which: It has a normal operation mode and a start-up mode, and in the start-up mode, before the start-up of the steam turbine is completed, the load setting from the central power supply station is accepted by limiting it to a range smaller than the normal operation state, and the operation is started. and a function of canceling the restriction and returning to normal operation mode after completion of startup. 8. Information representing the load setting from the central power supply station and the state of the plant, provided in a combined power generation plant that has a gas turbine and a steam turbine as power sources and generates power according to the load setting from the central power supply station. A load control device that commands fuel increase/decrease of a gas turbine based on the system, comprising: a unit load setting section that sets and commands a load according to the state of the plant at the time of startup; and a load setting section from the central power supply station. a switching unit that switches between the command and the load setting command from the unit load setting unit according to the state of the plant; A combined power generation plant comprising: a load increase/decrease command unit that commands an increase/decrease; and a load change rate setting unit that sets a load change rate according to the load increase/decrease command and outputs a fuel increase/decrease command. Load control device.