JPS6246681B2 - - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a gas turbine control device, and more particularly to a gas turbine control device suitable for use in a combined power generation plant to improve load followability.

Technical Background of the Invention In recent thermal power plants, as fuel prices have soared, there has been a demand for improved load followability, including start-up and shutdown, as part of efforts to improve thermal efficiency and make thermal power plants more middle-sized. is increasing. As one solution to these demands, combined cycle power plants that combine a gas turbine and a steam turbine have been attracting attention.

In order to increase the thermal efficiency of the entire plant, the gas turbines used in such combined power generation plants are designed to increase the exhaust temperature of the gas turbine, increase the amount of steam generated by the waste heat recovery boiler, and increase the output of the steam turbine. Efforts have been made to make it possible. As an example, a method is known in which the inlet stationary blades of the gas turbine are made variable to reduce the amount of air flowing into the gas turbine at partial load, thereby increasing the gas turbine exhaust temperature.

FIG. 1 shows a system diagram of such a well-known gas turbine for a combined power generation plant, and particularly describes a conventional system for increasing the exhaust temperature of a gas turbine having variable inlet stator vanes.

In the configuration shown in FIG. 1, a variable inlet stator vane 2 is provided at the compressor inlet 1, and the amount of air flowing into the compressor 3 is controlled. The air compressed by compressor 3 is sent to combustor 4
It is used for combustion of fuel 6, the flow of which is regulated by a fuel control valve 5. High-temperature gas 7 generated as a result of combustion is sent to a gas turbine 8 and is discharged as exhaust gas 9 after performing work while expanding. Note that the rotating shaft of the gas turbine is the generator 10.
etc. is connected to the load. The exhaust gas 9 from the gas turbine 8 is high-temperature and is sent to the waste heat recovery boiler 11, where it exchanges heat with the boiler's feed water to generate steam, which performs work in a steam cycle on the steam turbine side (not shown).

FIG. 2 is a block diagram of a conventional gas turbine control device applied to the gas turbine 8 shown in FIG. As shown in FIG. 2, the control of the gas turbine 8 is broadly divided into a startup control circuit 11, a speed load control circuit 12, a temperature control circuit 13, and an inlet variable stator vane control circuit 14. startup, speed load,
The fuel control signals from each temperature control circuit are passed through the low value priority circuit 15 and the lowest value is the fuel control valve control circuit 1.
Sent to 6. The output signal from the fuel control valve control circuit 16 is sent to the fuel control valve 5 to adjust its opening, but in this case, the opening of the fuel control valve 5 is returned to the fuel control valve control circuit 16 as a feedback signal 17. . On the other hand, the speed control circuit 12 receives the sum of the rated rotational speed bias from the bias setter 8a and the set value from the load setting device 18, and the actual rotational speed of the gas turbine 8 detected by the rotational speed detector 19. The deviation signals are added by an adder 20 and applied. Further, the temperature control circuit 13 is supplied with an output signal of a temperature setting device 21 that generates a signal corresponding to the discharge pressure of the compressor 3 and an output signal of an exhaust gas temperature detector 22 that detects the temperature of the exhaust gas 9 of the gas turbine 8. A deviation signal is calculated by the adder 23 and applied. Furthermore, the inlet variable stator vane control circuit 14 receives an output signal from a temperature setting device 24 that generates a signal corresponding to the discharge pressure of the compressor 3, like the temperature control circuit 13, an output signal from the exhaust gas temperature detector 22, and the temperature. A negative bias set in the setter 25 to prevent interference with the control circuit 13 is calculated by the adder 26 and inputted. The output signal of the variable inlet stator vane control circuit 14 is sent to the variable inlet stator vane position control circuit 27, and the variable inlet stator vane 2 is operated. The position of the inlet variable stator vane 2 is determined by the inlet variable stator vane position control circuit 27 as a feedback signal 28.
The positioning control is then performed.

With this configuration, during the startup process of the gas turbine 8, the startup control circuit 11 generates fuel control signals necessary for ignition and acceleration of the gas turbine 8, but the fuel control signals from the speed control circuit 12 and the temperature control circuit 13 are generated. Both fuel control signals generate the maximum signal because the actual rotational speed of the gas turbine 8 is low and the temperature of the exhaust gas 9 of the gas turbine 8 is low, and therefore, the startup control is performed through the low value priority circuit 15. The signal from circuit 11 is selected. A signal from the activation control circuit 11 is given to a fuel control valve control circuit 16 to control the amount of fuel.

Next, when the rotational speed of the gas turbine 8 increases and becomes close to the rated rotational speed, control is transferred from the startup control circuit 11 to the speed load control circuit 12. Furthermore, as the gas turbine 8 is added and the load is increased, the exhaust gas temperature of the gas turbine 8 increases, and the temperature control circuit 13 then limits the amount of fuel.

Incidentally, the inlet variable stator vane 2 is controlled by the inlet variable stator vane position control circuit 27 so as to maintain the exhaust gas temperature of the gas turbine 8 at a high value independently of the startup, speed load, and temperature control circuits.

FIG. 3 is a characteristic diagram showing the process of change in exhaust gas temperature with respect to the gas turbine output of the gas turbine 8 controlled by the gas turbine control device as shown in FIG. The output and the exhaust gas temperature are shown on the vertical axis. In the figure, a broken line A is a temperature limit curve in the temperature control circuit 13. As the gas turbine output increases, the exhaust gas temperature changes along the thick solid line, but this is a nearly downward-sloping characteristic because the gas turbine inlet temperature is kept constant and the temperature This is to prevent burnout of the combustor, the first stage nozzle of the turbine, etc. due to the rise. Also,
The solid line B is the temperature limit curve produced by the inlet variable stator vane control circuit 14, and the difference between the broken line A and the solid line B is the bias signal produced by the setter 25.

Now, when the gas turbine is operated under partial load, the inlet variable stator vanes are at the minimum opening position, so they are not affected by the inlet variable stator vane control circuit 14, so the exhaust air is as shown in the thick line - section. Shows gas temperature characteristics. Next, when the output of the gas turbine 8 is increased, the amount of air flowing into the gas turbine 8 is controlled by the variable inlet stator vane 2 by the variable inlet stator vane control circuit 14, and the exhaust gas temperature is maintained high. When the output of the gas turbine 8 is further increased, the exhaust gas temperature is controlled as shown in the thick line - section, but during this time, the opening degree of the inlet variable stator blade increases as the output of the gas turbine 8 increases. It is fully opened at the position. Furthermore, when the output of the gas turbine 8 is increased, the exhaust gas temperature increases along a curve C that is the operating characteristic of the gas turbine 8 without the variable inlet stator vanes 2. As a result, when the exhaust gas temperature reaches a point V where it intersects with the broken line A, the fuel is restricted by the action of the temperature control circuit 13 and the maximum output is reached.

Problems with the Background Art As described above, in the conventional gas turbine control device applied to a gas turbine having variable inlet stator blades, when increasing the load, the speed load control circuit 1
When the exhaust gas temperature of the gas turbine rises due to a fuel increase command from 2, the inlet variable stator vane 2 opens to increase the air flow rate so that the temperature does not exceed a predetermined temperature.
Although an attempt is made to keep the temperature constant, in this case the temperature tends to rise transiently, and the variable inlet stator vane 2 operates after the temperature rises, resulting in poor load followability. In other words, there is a drawback that the exhaust gas temperature rises transiently and the load followability deteriorates due to the delay in response due to the opening of the variable inlet stator vane 2 after sensing the rise in the exhaust gas temperature of the gas turbine 8. In addition, since the exhaust gas temperature is controlled by controlling the variable inlet stationary vanes 2, the amount of air flowing into the gas turbine 8 changes, and the load command signal in the speed load control circuit 12 and the actual output signal of the gas turbine 8 change. As a result, there is a problem that control performance is deteriorated.

Purpose of the Invention Therefore, the purpose of the present invention is to solve the problems of the prior art, to make the actual gas turbine output accurately follow the gas turbine load command request, and to improve the load followability when the load changes. It is an object of the present invention to provide a new gas turbine control device that is improved and further suppresses temperature rise during transient periods.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a gas turbine control device for a power generation system that generates electric power by a gas turbine having variable inlet stator blades and a steam turbine driven by the exhaust gas thereof; A speed load control means that detects the actual load of the turbine and compares it with a load command and controls the fuel of the gas turbine based on the obtained load deviation and the rotational speed of the gas turbine, and the load deviation from the speed load control means and the gas It is comprised of an inlet variable stator vane control means that controls the opening degree of the inlet variable stator vane based on the exhaust gas temperature of the turbine and a temperature setting signal.

Embodiments of the Invention Examples of the present invention will be described below with reference to the drawings.

FIG. 4 shows a partial block diagram of a gas turbine control device according to an embodiment of the present invention, and the difference from the configuration of FIG. 2 is that the speed load control circuit 1
2 and the input side configuration of the inlet variable stator vane control circuit 14. That is, the load setting for the gas turbine 8 is performed by the load setting device 18, but in the configuration of this embodiment shown in FIG. The adder 33 compares the output signal of the converter 32 with the output signal of the adder 33, and this deviation is given to the load setting device 18. In the load setter 18, the set value is modified until the output of the adder 33 becomes zero. In addition, the load setting device 18
is composed of a memory-type circuit such as a motor-driven potentiometer, digital setting device, or integrator, and when the deviation signal from the adder 33 becomes zero, that is, the output of the gas turbine generator reaches the load setting command device. When the load becomes the same as the desired load set in 31, the set value of the load setter 18 is stored and held at a constant value. Therefore, the change in the output of the gas turbine 8 whose air amount is reduced by the variable inlet stator vane is corrected by modifying the setting signal of the load setting device 18. On the other hand, in the configuration of this embodiment, the deviation signal between the output signal of the load setting command device 31 and the output signal of the actual load detector 32, that is, the output signal of the adder 33, is sent to the inlet variable stator vane through the gain converter 34. By adding it to the adder 26 provided on the input side of the control circuit 14, transient temperature increases in the gas turbine 8 are suppressed and load followability is improved.

In this configuration, when a deviation signal is generated in the adder 33 as the load increases, this is provided to the speed load control circuit 12 via the load setting device 18,
In addition to increasing the fuel in the combustor 4 of the gas turbine 8, a signal is applied to the adder 26 of the variable inlet stator vane control circuit via the gain converter 34 in a direction to open the variable inlet stator vane 2. 8 air volume increases. By implementing the two controls described above, it is possible to prevent a transient temperature rise of the gas turbine 8 and to improve load followability.

In the configuration shown in FIG. 4, the case where the gas turbine generator output is detected through the actual load detector 32 has been exemplified, but as shown in the block diagram of FIG. The exhaust temperature 32b and the compressor discharge pressure 32c may be detected, and by inputting these to the output calculation circuit 32d, the gas turbine generator output may be calculated and compared with the output signal of the load setting command device 31.

FIG. 6 is a partial block diagram of a gas turbine control device according to another embodiment of the present invention, in particular, as shown in the system diagram of FIG. 7, the compressor 3, gas turbine 8, steam turbine 35, and generator 10 are This exemplifies a configuration that can be effectively applied to configurations arranged on the same axis.

That is, in the combined cycle of the type shown in FIG. 7, the output of the generator 10, that is, the actual load, is the sum of the outputs of the gas turbine 8 and the steam turbine 35, so the net output of the gas turbine 8 cannot be detected. I can't. On the other hand, it is possible to correct this by multiplying the output signal of the generator 10 by a coefficient according to the output sharing between the gas turbine 8 and the steam turbine 35, but when the load is changed, the Since the waste heat recovery boiler has a poor ability to follow changes, the output of the steam turbine 35 does not change at a constant rate according to the above-mentioned coefficient.

On the other hand, in the configuration shown in FIG. 6, the pressure in the first stage of the steam turbine is detected using the principle that the output of the steam turbine 35 is proportional to the pressure in the first stage of the steam turbine 35. A calculation circuit 36 is provided to calculate the steam turbine output, and its output signal is input to an adder 37 to subtract it from the output signal of the generator actual load detector 32 to obtain the true gas turbine output. ing.

With this configuration, it is possible to prevent the gas turbine from compensating for a delay in load follow-up of the steam turbine 35 during a transient load change, and to prevent the gas turbine from operating overload.

Effects of the Invention As described above, according to the present invention, it is possible to accurately follow the actual gas turbine output with respect to the gas turbine load command, improve the load followability when the load changes, and further improve the temperature rise. By making it possible to suppress this, it is possible to obtain a gas turbine control device with high operability and reliability.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a conventional gas turbine, Figure 2 is a block diagram of a conventional gas turbine control device, and Figure 3 is a characteristic diagram showing the relationship between gas turbine output and gas turbine exhaust gas temperature during combined cycle operation. , FIG. 4 is a partial block diagram of a gas turbine control device according to an embodiment of the present invention, FIG. 5 is a block diagram showing another example of an actual load detector, and FIG. 6 is a partial block diagram of a gas turbine control device according to an embodiment of the present invention. FIG. 7 is a system diagram showing the configuration of a uniaxial combined cycle to which the configuration of FIG. 6 is applied. 2... variable inlet stator vane, 3... compressor, 4... combustor,
8...Gas turbine, 11...Start control circuit, 12...
Speed load control circuit, 13...Temperature control circuit, 14...
Inlet variable stator vane control circuit, 15...Low value priority circuit, 1
8... Load setting device, 20, 23, 26, 33... Adder, 31... Load command device, 32... Actual load detector, 3
4...Gain converter.

Claims (1)

[Claims] 1. A power generation system that generates electric power by a gas turbine having variable inlet stator blades and a steam turbine driven by its exhaust gas, and detecting the actual load of the gas turbine and comparing it with a load command. and speed load control means for controlling the fuel of the gas turbine based on the obtained load deviation and the rotational speed of the gas turbine, and the load deviation from the speed load control means, the gas turbine exhaust gas temperature, and a temperature setting signal. 1. A gas turbine control device comprising: an inlet variable stator vane control means for controlling the opening degree of the inlet variable stator vanes based on the opening angle of the inlet variable stator vanes. 2. The gas turbine control device according to claim 1, wherein the speed load control means uses a signal obtained by subtracting the output of the steam turbine from the total load of the power generation system as the actual load of the gas turbine. 3. The gas turbine control device according to claim 1, wherein the inlet variable stator vane control means includes a coefficient unit that multiplies the load deviation from the speed load control means by a constant coefficient.