JPS58124010A - Controller for gas turbine - Google Patents

Abstract

PURPOSE:To contrive an improvement of follow-up performance and control of a temperature increase during a transitional period, by a method wherein fuel is controlled based on a deviation for an actual load and load instructions and a revolution of a gas turbine, and an opening of an inlet variable stator blade is controlled based on a temperature of exhaust gas and a temperature setting signal. CONSTITUTION:When a deflection signal is generated on an adder 33 according to an increase of a load, it is given to a speed load control circuit 12 through a load setting device 18, through which fuel of a burner 4 of a gas turbine 8 is increased and the signal is added to an adder 26 of an inlet variable stator blade control circuit 14 in a direction of opening an inlet variable stator blade 2 through a gain converter 34, then an air quantity of the gas turbine 8 is increased. A transitional temperature rise of the gas turbine 8 can be prevented from occurring and follow-up performance of a load can be made to improve by controlling like this.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a gas turbine control device, and particularly relates to a gas turbine control device suitable for use in a combined cycle power plant to improve load followability. Background In recent years, in thermal power plants, as fuel prices have soared, there has been an increasing demand for improvements in load followability, including start-up and stoppage, as part of efforts to improve thermal efficiency and make thermal power plants more middle-sized. ing. 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 more expensive. As an example, a method is known in which the intake airfoil of the gas turbine is made variable to reduce the inflow air pressure of the gas turbine at partial load, thereby increasing the gas turbine exhaust temperature.

The first WA shows a system diagram of such a well-known gas turbine for a Kawakin power generation plant, and in particular concerns a conventional method of increasing the exhaust temperature of a gas turbine containing variable inlet stator blades! ff1F! In the configuration shown in Figure 1, the compressor population is 1, and the inlet variable stator vane is 2.
The amount of air flowing into the compressor 3 is controlled. The air compressed by the compressor 3 is sent to the combustor 4, and is used for combustion of fuel 6 whose flow is regulated by the fuel control valve 5. The high-temperature gas 7 generated as a result of the combustion is sent to a gas turbine 8, performs work while expanding, and is then discharged as exhaust gas 9. 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 sent to the waste heat recovery boiler 11 due to its high temperature, where it exchanges heat with the boiler's feed water to generate steam, which is then processed in a steam cycle on the steam turbine side (not shown). 1 is a block diagram of a conventional gas turbine control device applied to the gas turbine 8 shown in FIG. 1. FIG. As shown in Figure 2,
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. Fuel control signals from the startup, speed load, and temperature control circuits are routed to the low value priority circuit 15.
The minimum value is sent to the fuel control valve control circuit 16 throughout.

The output signal from the fuel adjustment valve control circuit 16 is returned to the fuel adjustment valve control circuit 16 for fuel adjustment. On the other hand, the speed control circuit 12 is supplied with the rated rotational speed bias from the bias setter 8a, the sum of the set value from the load setting device I8, and the rotational speed detector 1.
A deviation signal from the actual rotational speed of the gas turbine 8 detected by the adder 9 is added by an adder and applied. Further, the temperature control circuit 13 is supplied with an output signal from a temperature setting device 2 which generates a temperature signal according to the discharge pressure of the compressor 3 and an output signal from an exhaust gas temperature detector 2 which detects the temperature of the exhaust gas 9 of the gas turbine 8. The deviation signal of the signal is calculated by an adder and applied to 0, and
The inlet variable stator vane control circuit 14 is supplied with an output signal from a temperature setting device that generates a signal corresponding to the discharge pressure of the compressor 3, like the temperature control circuit 13, an output signal from an exhaust gas temperature detector η, and a temperature control circuit. Setter 5 to prevent interference with 13.
The negative bias set to is calculated and input to the adder. The output signal of the variable inlet stator vane control circuit 14 is sent to the variable inlet stator vane position control circuit n, and the variable inlet stator J[2 is operated. Incidentally, the position of Oguchi-cho Henseiko 2 is returned as a feedback signal train to the entrance-cho Henseiki position control circuit n for position determination control, 'μ.

With this configuration, during the startup process of the gas turbine 8, the startup control circuit 11 generates a fuel control signal necessary for igniting and accelerating the gas turbine 80, but the fuel control signal from the speed control circuit 12 and the temperature control circuit 13 Since 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, the maximum signal tube is generated in each control signal, and therefore, the control signal is transmitted to the startup control circuit 11 through the low value priority circuit 15. The signal from 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 4 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 shows a characteristic 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. 2, where the horizontal axis shows the gas turbine output; The vertical axis shows the exhaust gas temperature. In the figure, a broken line indicates 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 the reason why this is a nearly downward slope is because the gas turbine inlet temperature is kept constant and the temperature It is a friend that prevents burnout of the combustor, first stage nozzle of the turbine, etc. due to rising. Further, the solid line B is a temperature limit curve produced by the inlet variable stator vane control circuit 14, and the difference between the two lines, the broken line A and the solid line B, is the bias signal produced by the setter 5.

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 thick line 1-1
The exhaust gas temperature characteristics are shown in one section. Next, as the output t-m 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 control circuit 14 by the variable inlet -s2, and the exhaust gas temperature increases. .

When the output of the gas turbine 8 is increased, the exhaust gas temperature is controlled as shown in the thick line [1-1-IV section, but during this time, the opening of the variable inlet stator vanes changes as the output of the gas turbine 8 increases. It gradually opens and becomes fully open at the ■ position. Furthermore, when the output of the gas turbine 8 is increased, the exhaust gas temperature increases along a curve C which 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 temperature control circuit 13
Due to zero action, fuel is limited and maximum power 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 gas turbine is controlled by a fuel increase command from the speed load control circuit 2. When the exhaust temperature rises, the inlet variable stator vane 2 opens to increase the air flow rate and keep the temperature constant to prevent it from exceeding a predetermined temperature, but in this case, the temperature tends to rise transiently, and the temperature also increases. In other words, the variable inlet stator vane 2 opens after detecting the rise in the exhaust gas temperature of the gas turbine 8, resulting in a delay in response. This has the disadvantage that the exhaust gas temperature rises transiently, resulting in poor load followability. Also, since the exhaust gas temperature is controlled by controlling the variable inlet stator blades 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 of the gas turbine 8 change. Since the signals become different, there is a problem that control performance is deteriorated.

Purpose of the Invention Accordingly, 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 novel gas turbine control device that further suppresses temperature rise during transient periods.

SUMMARY OF THE INVENTION To achieve the above objects, the present invention provides a power generation system that generates electric power by a gas turbine having a gas turbine control wave m 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.

Examples of the invention Hereinafter, the present invention will be described in detail 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 differences from the configuration in FIG. 2 are a speed load control circuit 12 and an inlet variable stator vane control circuit 14. The input side configuration is IC6. 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 output signal of 32 is compared with the output signal of 32 in an adder, and this deviation is given to the load setter 18. In the load setter 18, the set value is corrected until the output of the adder 6 becomes zero. The load setting device 18 is composed of a memory-type circuit such as a motor-driven potentiometer, a digital setting device, an integrator, etc., and when the deviation signal from the adder becomes zero, that is, the output of the gas turbine generator changes. When the load becomes the same as the desired load set in the load setting command device 31, the set value of the load setting device 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 (that is, the output signal of the adder 33) is converted to the input variable stator vane through gain conversion. Control circuit 14
By adding the input side pressure to the addition 6, transient temperature rise of the gas turbine 8 is suppressed and load followability is improved.

In such a configuration, when a deviation signal is generated in the addition 633 due to an increase in load, this signal is applied to the speed load control circuit 12 via the load setter 18 to increase the fuel in the combustor 4 of the gas turbine 8. At the same time, the inlet variable stator vane 21 is connected to the inlet variable stator vane 21 via the adder A and the gain converter A of the inlet variable stator vane control circuit.
Since a signal is applied in the direction of opening the gas turbine 8, the amount of air in the gas turbine 8 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 gas turbine generator output is detected through the actual load detector 32'fr; however, as shown in the block diagram of FIG. 32a, gas turbine exhaust temperature E2b.

Compressor discharge pressure 32cf: It may be configured to detect and input these to the output calculation circuit 32d to calculate the gas turbine generator output and compare it with the output signal of the load setting command device 31.

FIG. 6 is a partial block diagram of a gas turbine control system according to another embodiment of the present invention. In particular, as shown in the system diagram of FIG. 7, a compressor 3, a gas turbine 8, a steam turbine 8, a generator This exemplifies a configuration that can be effectively applied to a configuration in which 10 are 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, so it is impossible to detect the net output of the gas turbine 8. Can not. On the other hand, it is also 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, but when the load is changed, the change in the gas turbine output The output of the steam turbine does not change at a constant rate with respect to the above-mentioned coefficient σ due to the poor followability of the waste heat recovery boiler against the Utilizing the principle that the output of the steam turbine 5 is proportional to the pressure of the first stage of the steam turbine 5, an arithmetic circuit is provided which calculates the steam turbine output by detecting the pressure of the first stage of the steam turbine. By inputting this into the adder 37, this is subtracted from the output signal of the generator actual load detection to obtain the true gas turbine output. With this configuration, the steam turbine can follow that load during transient load changes. The gas turbine side does not compensate for the delay in
It is also possible 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 in response to the gas turbine load command, improve the load followability when the load changes, and further reduce the temperature rise. By making it possible to suppress this, it is possible to obtain a gas turbine control system rIt with high operability and reliability.

[Brief explanation of drawings]

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;
The figure is a partial block diagram of a gas turbine control device according to another embodiment of the present invention, and FIG. 7 is a system diagram showing the configuration of a uniaxial combined cycle to which the configuration of FIG. 6 is applied.

Claims (1)

[Claims] 1. A power generation system that generates electric power by a steam turbine driven by exhaust gas having a variable inlet stator vane, and detecting the actual load of the gas turbine and comparing it with a load command, speed load control means for controlling the fuel of the gas turbine based on the obtained constant load deviation and the rotational speed of the gas turbine; A gas turbine control device comprising: variable inlet stator vane control means for controlling the opening degree of the variable inlet stator vanes. 2. The gas turbine control device C according to claim 1, wherein the speed load control means sets 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.