JPH0586810A - Load control method for composite power generating plant and device therefor - Google Patents

Abstract

PURPOSE:To economically control the number of gas turbines to be operated at high efficiency by conducting a plant load lowering operation to a target load of a plant with all of the gas turbines when the plant load is decreased, and maintaining the target load with the required gas turbines after the target load is achieved. CONSTITUTION:In a composite power generating plant, a plurality of gas turbines 3a-3c are disposed in parallel. Exhaust heat of the gas turbines 3a-3c is recovered in exhaust heat recovery boilers 5a-5c, respectively. One steam turbine 6 is driven by steam generated by heating in the recovery boilers 5a-5c. The three gas turbines 3a-3c drop load until a plant load becomes 50%. When the plant load becomes 50%, the gas turbine 3a further drops the load, to be stopped. The residual gas turbines 3b, 3c perform operation for maintaining the plant load at 50%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control method and apparatus for a combined cycle power plant, and more particularly to a load control method and apparatus suitable for load control by increasing or decreasing the number of operating gas turbines.

[0002]

2. Description of the Related Art When operating a combined cycle power plant having a plurality of gas turbines with high efficiency and economy, the number of operating gas turbines is controlled. In the conventional technique described in Japanese Patent Publication No. 60-523, the result of comparison between the power supply command given to each power plant under each power system and the maximum possible output for each operating number of gas turbines, or when the gas turbine is started or stopped The optimum number of operating gas turbines for a given power supply command is selected based on the result of comparing the heat loss of the is doing.

[0003]

The above-mentioned prior art gives optimum answers regarding the determination of whether or not the number of operating gas turbines needs to be increased or decreased and the method of determining the number of operating gas turbines. There is a problem in that it does not consider whether to operate each gas turbine individually.

An object of the present invention is to provide a load control method and apparatus for controlling the operation of gas turbines with high efficiency and economically when the number of operating gas turbines is increased or decreased to cope with the increase or decrease of plant load. is there.

[0005]

The above-mentioned object is to increase or decrease the number of operating gas turbines of a combined cycle power plant composed of a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. Load control,
When the plant load decreases, the plant load reduction operation is performed on all the gas turbines up to the target load of the plant, and after reaching the target load, only the required gas turbine is lowered or stopped and the remaining gas turbine is set to the target load. This is achieved by maintaining operation. (Inventions of Claims 1 and 7) The above object is also achieved by operating only the required gas turbines so that the load is reduced or stopped when the plant load decreases and the remaining gas turbines operate so as to reach the plant target load. To be done. (Invention of Claims 2 and 8) In addition, when the plant load is reduced, only the required gas turbine is lowered or stopped, and the remaining gas turbines perform the plant load reduction operation to the target load of the plant, and thereafter, By operating to maintain the target load,
To be achieved. (Invention of Claims 3 and 9) The above-mentioned object is also that when the plant load increases, the gas turbine under continuous operation continues the gas turbine load,
The stopped gas turbine starts and increases the load by using the gas turbine load as a target load, and after the additionally started gas turbine reaches the target load, the gas turbine is put into parallel operation with the gas turbine that is continuing operation, and then the operation is performed. This is achieved by controlling the plant load on all of the middle gas turbines. (Invention of Claims 4 and 10) In addition, when the plant load increases, the above object is to control the gas turbine during continuous operation to shift to the target load of the plant, and to stop the gas turbine after the start-up of the target load. The load rises up to, and the additionally started gas turbine enters parallel operation with the gas turbine that is continuing operation after reaching the target load.
After that, this is achieved by performing plant load control on all operating gas turbines. (Invention of Claims 5 and 11) In addition, when the plant load increases, the above object is to control the gas turbine under continuous operation so as to shift to the target load of the plant, and the gas turbine under shutdown continues to operate after starting. The gas turbine load or the load increase to the same operating condition,
This is achieved by operating the gas turbine that has been additionally started when the load is the same or in the same operating state and operating the gas turbine in parallel, and then performing plant load control on all operating gas turbines. .. (Inventions of Claims 6 and 12)

[0006]

[Operation] When the plant load decreases, the plant load down operation is performed on all the gas turbines up to the target load of the plant, or only the required gas turbine among them is stopped, and after reaching the target load, only the required gas turbine is loaded. By performing the operation of lowering or stopping and maintaining the target load in the remaining gas turbines, the plant load following when the number of operating gas turbines decreases is performed in the necessary minimum time.

When the plant load decreases, only the required gas turbine is lowered or stopped, the remaining gas turbines perform the plant load reduction operation up to the plant target load, and then perform the operation for maintaining the target load. Minimize the operation when the number of operating gas turbines decreases.

When the plant load increases, the gas turbine under continuous operation continues the gas turbine load, and the stopped gas turbine starts and increases the load with the gas turbine load as a target load. After the turbine reaches the target load, it enters into parallel operation with the gas turbine that is still in operation, and after that, by performing plant load control on all operating gas turbines, the operation when increasing the number of operating gas turbines is performed. Minimize it as necessary.

When the load on the plant increases, the gas turbine under continuous operation is controlled to shift to the target load of the plant, and the gas turbine under stop increases its load up to the target load after startup, and the additionally started gas turbine is After the target load is reached, parallel operation is started with the gas turbine in operation, and then the plant load control is performed for all operating gas turbines. To load.

When the plant load increases, the gas turbine in continuous operation is controlled to shift to the target load of the plant, and the gas turbine in stop is loaded to the gas turbine load in continuous operation after startup or to the same operating state. Then, when the same load or the same operating state is reached, the gas turbine that has been additionally started and the gas turbine that is still operating are operated in parallel,
Then, by performing plant load control on all operating gas turbines, a stable plant load is obtained until the operation is completed when the number of operating gas turbines is increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 7 is a configuration diagram of a multi-axis combined power plant. In this combined cycle power plant, three gas turbines 3a, 3b, 3c are installed in parallel and each gas turbine 3
Exhaust heat of a, 3b, 3c is respectively collected by the exhaust heat recovery boilers 5a, 5a.
b, 5c to recover the exhaust heat recovery boilers 5a, 5b,
One steam turbine 6 is driven by the steam obtained by heating at 5c. Each gas turbine 5a (5
Since the same applies to b and 5c, only the system of 5a will be described, but the same applies to the other systems of 5b and 5c. ), An air compressor 1a is coaxially attached. The air Aa in the atmosphere is pressurized by the rotation of the air compressor 1a and is sent into the combustor 2a, where it is burned together with the fuel Fa. Combustion gas enters the gas turbine 3a,
Here, mechanical power is generated and converted into electric energy by the generator 4a. The hot exhaust gas that has finished its work in the gas turbine 3a is guided to the exhaust heat recovery boiler 5a, where water exchanges heat with the hot exhaust gas to become steam. The exhaust gas emitted from the exhaust heat recovery boiler 5a is released into the atmosphere via the chimney 10.

The steam generated in the exhaust heat recovery boiler 5a is collected in the main steam pipe 14 together with the steam from the other boilers 5b and 5c via the steam stop valve 11a, passes through the steam turbine inlet valve 13 and the steam turbine 6 to go into. The mechanical power generated here is converted into electric energy by the generator 7. The exhaust steam that has finished its work in the steam turbine 6 becomes condensed water in the condenser 8 and is supplied to the exhaust heat recovery boiler 5a by the water supply pump 9. Also, depending on some conditions, the exhaust heat recovery boiler 5
When the steam generated in “a” becomes excessive, the turbine bypass valve 12 a opens and the surplus steam is discharged to the condenser 8 through the turbine bypass pipe 15.

As one of the operations of such a multi-axis type combined power generation plant, there is a gas turbine operating unit number control described in Japanese Patent Publication No. 60-523, which is indispensable for operating the plant highly efficiently and economically. is there. When performing the control of the number of operating gas turbines, in the present embodiment, the load control of the gas turbine is performed as follows.

FIG. 1 shows a first embodiment of the present invention (claim 1,
Plant load PL in load control according to
It is a graph which shows the time change of steam turbine load STL and gas turbine load GTL. In this embodiment, the gas turbine 3a is stopped and the remaining gas turbines 3b and 3c are operated when the plant load PL1 is reduced from 100% to 50% by the time t0 to t1. Therefore, first, the load is lowered by the three gas turbines 3a, 3b, 3c until the plant load PL1 becomes 50%, and when it becomes 50% at time t1, the gas turbine 3a is further lowered and stopped, and the remaining Plant load PL with the gas turbines 3b, 3c of
1 to maintain 50%, steam turbine load STL1
Gas turbine load GTL1b, GTL1c
Perform the load increase operation of. As a result, the load STL1 of the steam turbine 6 and the loads GTL1b and GTL1c of the gas turbines 3b and 3c are also settled at time t2.

The characteristic of the load STL1 of the steam turbine 6 is:
Exhaust heat recovery boiler 5a, 5 which is a feature of the combined cycle power plant
This is due to the delay in the response of steam generated in b and 5c.
Therefore, in order to cover this response delay, the load GTL1 of the gas turbines 3a, 3b, 3c temporarily drops,
Load GTL1b of the gas turbines 3b and 3c that continue to operate,
Only GTL1c is increased to the settling load (load at time t2) after the continuous reduction of the number of operating gas turbines.

When the load STL1 of the steam turbine 6 is settled at time t1 (the same load as at time t2), the turbine bypass valves 12a, 12b, 12c in FIG.
It is possible to open at least one of the above and allow a part of the steam entering the steam turbine 6 to flow directly to the condenser 8. In this case, since the time required for the plant load PL1 to reach 50% is earlier than t1, the gas turbines 3b, 3c
The load GTL1b and GTL1c can be reduced in a small amount.

FIG. 2 shows a second embodiment of the present invention (claims 2, 8).
Is a graph showing a time change of the plant load PL, the steam turbine load STL, and the gas turbine load GTL in the load control according to (1). In the present embodiment, when the plant load is reduced from 100% to 50%, the gas turbine 3a is lowered and stopped, and the remaining gas turbine 3
Operate so that the plant load becomes 50% in b and 3c. In general, the load change rate when the gas turbines 3a, 3b, 3c are stopped and the load change rate during normal operation have the same value, so even if the gas turbine 3a is stopped from the time t0, the plant load PL Even if the rotation is stopped after the rotation reaches 50%, the load characteristics are similar (Fig. 1
GTL1a = GTL2a in FIG. 2). Therefore, the loads GTL2b, GTL of the gas turbines 3b, 3c that continue the operation
2c and load STL2 of steam turbine 6 and plant load PL
2 has the same characteristics as in FIG. Similar to FIG. 1, the same characteristics are obtained when at least one of the turbine bypass valves 12a, 12b, 12c is opened.

FIG. 3 shows a third embodiment of the present invention (claim 3,
Corresponding to 9), the plant load PL in the load control according to
It is a graph which shows the time change of steam turbine load STL and gas turbine load GTL. In this embodiment, the load of the gas turbines 3b, 3c that continues to operate is lowered with the target of the settling load of the gas turbines 3b, 3c after the reduction of the number of operating gas turbines. That is, the second of FIG.
Gas turbine 3 settling at time t4 in the embodiment
In the present embodiment, the loads GTL2b and GTL2c of b and 3c are given as load reduction targets at time t0 in advance. After time t5 when this target load is reached, the gas turbines 3b, 3
The loads GTL3b and GTL3c of c become constant, and as the load STL3 of the steam turbine 6 drops, the plant load PL3
Also descends and settles at time t6. In this embodiment as well, similar to the first and second embodiments, the same characteristics can be obtained by opening at least one of the turbine bypass valves 12a, 12b, 12c.

FIG. 4 shows a fourth embodiment of the present invention (claim 4).
Corresponding to 10) plant load P in load control
L, steam turbine load STL, gas turbine load GTL
Is a graph showing the change over time, and relates to control when the plant load increases from the state in which the gas turbine 3a is stopped. In this embodiment, the plant load PL
When increasing 4 from 50% to 100% from time t0 to time t11, the gas turbine 3a is additionally started. Then, the gas turbines 3b, 3c load GTL4b, GT at the time when the gas turbine 3a starts up and enters the load operation
The load of the gas turbine 3a is increased by setting L4c as a standby or fixed load and using this load as a target load. If the load GTL4a of the gas turbine 3a becomes the same as the loads GTL4b and GTL4c (of course, a slight margin of plus or minus is allowed), and if the conditions of the steam generated from the exhaust heat recovery boiler 5a shown in FIG. 7 are satisfied. If (at least one state quantity of any one of pressure, temperature, flow rate, etc. is equal to or within an allowable deviation of the state quantity of steam from the exhaust heat recovery boilers 5b, 5c), the steam stop valve 11a is turned on. At time t8, the valve is opened and the generated steam flows into the steam turbine 6. That is, the parallel operation of the three gas turbines is started. During the period from the start of the gas turbine 3a to the opening of the steam stop valve 11a, the turbine bypass operation in which the steam generated in the exhaust heat recovery boiler 5a is passed to the condenser 8 via the turbine bypass valve 12a is performed.

When the steam stop valve 11a is opened and the turbine bypass valve 12a is fully closed (at time t9), the gas turbines 3a, 3b, 3c are loaded with GTL4 (the plant target after completion of the increase in the number of operating gas turbines). Load) to increase the load. In this process, the load S of the steam turbine 6
TL4 rises from time t8 and settles at time t11. Further, the plant load PL4 also rises from the time t0 and the time t11
It becomes the characteristic to settle with.

FIG. 5 shows a fifth embodiment of the present invention (claims 5 and 5).
(Corresponding to 11), the plant load P in the load control according to
L, steam turbine load STL, gas turbine load GTL
It is a graph which shows the time change of. This embodiment is substantially the same as the fourth embodiment, except that the loads GTL5b and GTL5c of the gas turbines 3b and 3c during the continuous operation are obtained from the time t0 so that the final target plant load is 100%. When the load GTL5a of the additionally started gas turbine 3a reaches 100% and the steam stop valve 11a and the turbine bypass valve 12a are operated and finished as in the fourth embodiment of FIG. At (time t15), the plant load PL has a characteristic of reaching the target load.

FIG. 6 shows a sixth embodiment of the present invention (claims 6 and 6).
(Corresponding to 12) plant load P in load control according to
L, steam turbine load STL, gas turbine load GTL
It is a graph which shows the time change of. In the present embodiment, the gas turbines 3b and 3c in continuous operation are operated to start the additionally started gas turbine 3a (the steam stop valve 11a is opened and the turbine bypass valve 12a is fully closed as in the fourth embodiment of FIG. 4). Until the time 18) is completed, the plant load PL6 is controlled so as to maintain the same load as the time t0 or the target arbitrary load at the time t0. Then, from time t18, the plant load is controlled by all the gas turbines 3a, 3b, 3c.

FIG. 8 is a block diagram of a uniaxial type combined power generation plant. In this combined cycle power plant, the gas turbine 3
Stands 3a, 3b, 3c and each gas turbine 3a, 3b, 3c
Three steam turbines 6a, 6 coaxially connected to each other
b, 6c, exhaust heat recovery boiler 5 of each gas turbine
The steam turbines 6a, 6b, 6c are individually driven by the steam generated by a, 5b, 5c.
The load control method in each of the above-described embodiments can also be applied to the combined power generation plant having such a configuration.

Although only the structure of the combined power generation plant is shown in FIGS. 7 and 8, the load control device for implementing the above-described load control method controls the combustor, the gas turbine, the exhaust heat recovery boiler, and various valves. Install it in a control panel (not shown) and execute it. It goes without saying that this load control device may be assembled with discrete electronic components or may be constructed in the form of computer software.

[0025]

According to the first and seventh or second and eighth aspects of the present invention, it is possible to follow the plant load when the number of operating gas turbines is reduced in a necessary minimum time.

According to the inventions of claims 3 and 9, it is possible to minimize the operation required when the number of operating gas turbines is reduced.

According to the inventions of claims 4 and 10, the operation when the number of operating gas turbines is increased can be minimized.

According to the inventions of claims 5 and 11, it is possible to achieve a predetermined plant target load upon completion of operation when the number of operating gas turbines is increased.

According to the inventions of claims 6 and 12, a stable plant load can be obtained until the operation is completed when the number of operating gas turbines is increased.

[Brief description of drawings]

FIG. 1 is a graph showing respective load characteristics of a plant load, a steam turbine load, and a gas turbine load in a load control method (when the number of operating gas turbines is reduced) according to the first embodiment of the present invention.

FIG. 2 is a graph showing load characteristics of a plant load, a steam turbine load, and a gas turbine load in the load control method (when the number of operating gas turbines is reduced) according to the second embodiment of the present invention.

FIG. 3 is a graph showing load characteristics of a plant load, a steam turbine load, and a gas turbine load in the load control method (when the number of operating gas turbines is reduced) according to the third embodiment of the present invention.

FIG. 4 is a graph showing respective load characteristics of a plant load, a steam turbine load, and a gas turbine load in a load control method (when the number of operating gas turbines is increased) according to a fourth embodiment of the present invention.

FIG. 5 is a graph showing respective load characteristics of a plant load, a steam turbine load, and a gas turbine load in the load control method (when the number of operating gas turbines is increased) according to the fifth embodiment of the present invention.

FIG. 6 is a graph showing load characteristics of a plant load, a steam turbine load, and a gas turbine load in the load control method (when the number of operating gas turbines is increased) according to the sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a multi-axis combined cycle power plant.

FIG. 8 is a configuration of a single-axis combined power plant.

[Explanation of symbols]

1a, 1b, 1c ... Air compressor, 2a, 2b, 2c ... Combustor, 3a, 3b, 3c ... Gas turbine, 4a, 4b,
4c, 7 ... Generator, 5a, 5b, 5c ... Exhaust heat recovery boiler, 6, 6a, 6b, 6c ... Steam turbine, 8, 8a,
8b, 8c ... Condenser, 9, 9a, 9b, 9c ... Water supply pump, 10 ... Chimney, 11a, 11b, 11c ... Steam stop valve,
12a, 12b, 12c ... Turbine bypass valve, 13,
13a, 13b, 13c ... Steam turbine inlet valve, 14,
14a, 14b, 14c ... Main steam pipes, 15, 15a, 1
5b, 15c ... Turbine bypass pipe.

Claims (12)

[Claims] 1. A load control method for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. When the load decreases, the plant load reduction operation is performed on all the gas turbines up to the target load of the plant, and after the target load is reached, only the required gas turbine is lowered or stopped and the remaining gas turbines maintain the target load. A load control method for a combined cycle power plant characterized by performing operation. 2. A load control method for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. When the load decreases, only the required gas turbine is lowered or stopped,
A load control method for a combined cycle power plant, comprising operating the remaining gas turbines so as to reach a plant target load. 3. A load control method for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. When the load decreases, only the required gas turbine is lowered or stopped,
A load control method for a combined cycle power plant, which comprises performing a plant load reduction operation to a plant target load with the remaining gas turbines, and then performing an operation to maintain the target load. 4. A load control method for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. When the gas turbine load increases, the gas turbine under operation continues the gas turbine load, and the stopped gas turbine starts and increases the load with the gas turbine load as the target load. A method for controlling load of a combined cycle power plant, comprising: performing parallel operation with a gas turbine that is operating continuously after reaching the point of ???, and then performing plant load control on all operating gas turbines. 5. A load control method for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. Is increased, the gas turbine during operation is controlled to shift to the target load of the plant, the gas turbine in stop increases the load to the target load after startup, and the additionally started gas turbine operates after reaching the target load. A load control method for a combined cycle power generation plant, which comprises performing parallel operation with an ongoing gas turbine and then performing plant load control on all operating gas turbines. 6. A load control method for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. Is increased, the gas turbine under continuous operation is controlled to shift to the target load of the plant, and the gas turbine under stop increases the load to the gas turbine load during continuous operation after startup or the same operating condition, When a gas turbine that is additionally started when the same operating state is reached and a gas turbine that is still operating are operated in parallel, then plant load control is performed on all operating gas turbines. Load control method. 7. A load control device for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. When the target load of the plant is reduced to a target load of the plant, a means for performing a plant load lowering operation, a means for lowering or stopping only the required gas turbine after reaching the target load, A load control device for a combined cycle power plant, comprising: means for performing an operation for maintaining a target load. 8. A load control device for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. A load control device for a combined cycle power plant, comprising: a means for lowering or stopping the load of only a required gas turbine when the load decreases; and a means for operating the remaining gas turbines so as to achieve a plant target load. 9. A load control device for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. When the load is reduced, a means for lowering or stopping the load of only the required gas turbine, a means for performing the plant load lowering operation to the plant target load with the remaining gas turbines, and a means for performing the operation for maintaining the target load thereafter. A load control device for a combined cycle power plant, comprising: 10. A load control device for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. Is increased, the gas turbine under continuous operation means for continuing the gas turbine load, a means for starting the gas turbine under stop with the gas turbine load as a target load to increase the load, and a gas for additional start-up. A composite comprising: a means for operating the gas turbine in parallel with the gas turbine that has continued to operate after the turbine reaches the target load; and a means for performing plant load control on all the operating gas turbines thereafter. Load control device for power plant. 11. A load control device for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. Is increased, means for controlling the gas turbine during continuous operation to shift to the target load of the plant, means for starting the stopped gas turbine to increase the load to the target load, and the additionally started gas turbine When the target load is reached, a means for operating in parallel with the gas turbine that is continuing operation, and a means for performing plant load control on all the operating gas turbines thereafter are provided. Load control device. 12. A load control device for increasing or decreasing the number of operating gas turbines of a combined cycle power plant comprising a plurality of gas turbines, an arbitrary number of exhaust heat recovery boilers, and an arbitrary number of steam turbines. , The means for controlling the gas turbine under continuous operation and shifting it to the target load of the plant, and the means for starting the gas turbine under stop and increasing the gas turbine load during continuous operation or the same operating state And a means for operating a gas turbine additionally started at the same load or in the same operating state in parallel with a gas turbine in continuous operation, and a means for thereafter performing plant load control in all operating gas turbines. A load control device for a combined cycle power plant, comprising: