JPH01240740A - Gas turbine control device - Google Patents

Abstract

PURPOSE:To improve the running reliability of the device in the title by controlling a pressure so that it may return back within a prescribed range, when the pressure on the upstream side from a fuel control value of fuel gas varies beyond the prescribed range. CONSTITUTION:A pressure control circuit consisting of a pressure setting apparatus 15, a subtracter 42 and the like is added to the speed load control unit 31 of a fuel control valve 13 for controlling the flow of fuel gas. When the variation between the set value of the pressure setting apparatus 15 and the upstream side pressure signal 16 of the fuel control valve 13 increases beyond the unsensible zone width of an unsensible zone circuit 17, the pressure control signal is added to the output of a load controller 4 and the pressure is controlled so as to be restrained within the set value. Thereby, even when the generating ability of fuel gas is low, the gas pressure and the load are controlled cooperatively and the running reliability can be improved.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a control device for a gas turbine that burns gas fuel to drive a turbine generator, and particularly relates to a control device for a gas turbine that burns gas fuel to drive a turbine generator. Alternatively, control is suitable for controlling gas turbines connected to gas generation equipment that have poor followability, have small gas volumes, and whose gas pressure changes sensitively in response to changes in fuel gas consumption in the gas turbine. It is related to the device.

(Prior Art) A typical gas turbine control system in the prior art is shown in FIG. 5. This example shows a gas turbine system driven by gas fuel.

The gas turbine 14 includes a compressor 81. Combustor 82. The turbine 83 is composed of turbines 83, each of which has complicated characteristics, high temperatures, and operational limitations due to being a rotating body, and its control device is also complicated.

The fuel gas generation unit 12 is a part that generates fuel gas to be sent to the gas turbine combustor 82, and in the case of natural gas (NG) firing, it is LNG vaporization equipment, and in the case of recent blast furnace exhaust gas fired gas turbines, it is a blast furnace. . Also, when considering the future coal gasification combined cycle, it refers to gasifiers and gas purification equipment that generate and purify coal gas. The fuel gas sent out from the fuel gas generating section 12 is sent to the combustor 82 of the gas turbine via the fuel control valve 13 of the gas turbine equipment.
The combustion gas is sent to the turbine 83 and becomes combustion gas to drive the turbine 83 and the generator 84 coupled thereto.

The control device for the gas turbine 14 is roughly divided into three control sections and a position priority device 11. They are given priority over other control signals so that the startup control section 9, which controls ignition fuel control at startup, warming, and control of increasing the rated speed, operates within the temperature limits allowable by the turbine blade metal. These include a temperature control section 6 that intervenes in control, and a speed/load control section 30 that controls the rotation speed and load of the turbine to target values. speed·
The load control unit 30 includes a speed controller IO and a circuit upstream thereof, and has a speed control function and a load control function. The signal leaving the speed controller IO is passed to the low value priority device ti
The signal from the speed controller IO is compared with the signal from the temperature control unit 6, and if the temperature is not limited, the signal from the speed controller IO becomes a fuel control signal and is given to the fuel control valve 13, the fuel flow rate is adjusted, and the speed and load are adjusted. control is performed.

The operation of this speed/load control section 30 will be explained in more detail below.

The setting signal of the load setter 1 is calculated by a subtracter 2 to calculate the deviation from the load signal 3, and then sent to a load controller (proportional integral element) 4.
is input to. The load controller 4 performs proportional/integral calculations and provides the adder 5 with a control output for eliminating load deviation. Adder 5 uses speed setter 7 (usually 5
0 King or 607) and the speed deviation of the speed signal 8 (when connected to the system, 501 (z or constant frequency of 60Hz)) is added and given to the speed controller 10.This speed deviation and the speed controller (Proportional element) 10 is a part called a governor, which does not operate when there is no fluctuation in the system frequency. At this time, the fuel control, that is, the output control of the turbine generator 84 is performed by the signal from the load controller 4. It will be done.

(Problem to be Solved by the Invention) As explained in the related art, load control of the gas turbine 14 is performed by controlling the opening degree of the fuel control valve 13 based on a signal from the speed/load control section 30. 1111, but as in the past, in the case of a gas turbine that has a fuel gas generation unit 12 that can send fuel gas very stably, for example an LNG base, the fuel is increased or decreased based on the load command. Even if this is done, there is no problem with the followability of the fuel gas generating section 12, and the fuel gas is always supplied at a stable pressure, allowing healthy load operation. However, if the gas turbine has a limited gas generation capacity, such as a gas turbine connected to a small-scale LNG vaporization facility, a blast furnace gas-fired gas turbine, or a coal gasification gas-fired gas turbine, the fuel gas delivery capacity is If there is a limit to (followability), it may not be possible to follow the fuel gas demand on the gas turbine side, leading to fluctuations in gas pressure.

That is, if fuel is increased or decreased on the gas turbine 14 side with a large load change range and at a high rate of change.

In the case of an increase in fuel, the fuel control valve 13 must be opened continuously, and if the follow-up ability of the fuel gas generating section 12 is low, this results in a decrease in gas pressure. Conversely, when the load decreases, the gas pressure increases.

High and low fluctuations in gas pressure are undesirable from the perspective of stable combustion in the gas turbine 14, and if the gas pressure exceeds a specified value, an interlock that switches from gas fuel to auxiliary fuel (diesel oil, etc.) is also installed in the gas turbine 14. The side has.

High and low fluctuations in gas pressure also have a negative effect on the fuel gas generation section 12.For example, in the case of the fuel gas generation section 12 such as coal gasification equipment, there is a problem with stable fuel supply due to the lock hopper, and the pressure When the amount of gas rises abnormally, the excess gas is released into the flare stack and released into the atmosphere after combustion.

As mentioned above, in conventional gas turbines, the fuel gas pressure control element is not considered at all in the fuel control of the gas turbine, and if the fuel is switched depending on the pressure level, there is a risk of a misfire trip. However, even if the fuel switching is successful, the load change must be stopped and the fuel switching (from liquid fuel to gas fuel) must be performed again. In this example, when the pressure is high, gas is released into the flare in order to keep the pressure to a specified value.
This is also unfavorable in terms of energy saving, and therefore, a method of controlling the fuel gas pressure and load in a coordinated manner that takes into account the element of fuel gas pressure control in the control on the gas turbine side is desired.

[Structure of the invention]

(Means for Solving the Problems) The present invention is a gas turbine control device that controls the flow rate of fuel gas supplied to a combustor of a gas turbine using a fuel control valve, in which the speed and load of the gas turbine are normally controlled. is controlled to approach a predetermined value, and only when the pressure on the upstream side of the fuel control valve of fuel gas fluctuates by more than a predetermined range, the pressure is controlled to return to within the predetermined range. .

(Function) If the gas pressure fluctuates beyond a predetermined range during speed/load control, the pressure can be pulled back.

This improves operational reliability.

(Example) Hereinafter, a first example of the present invention will be described based on FIG. In this figure, parts common to those of the prior art shown in FIG. 5 are given the same reference numerals and their explanations will be omitted. A control circuit for adding a pressure control element, which will be described below, is added to the speed load control section 31.

They include a pressure setting device 15 for setting the specified value of fuel gas pressure, a subtractor 42 for calculating the deviation from the pressure signal 16 (fuel gas pressure signal), and a pressure control function when the pressure deviation is within a certain value. Dead band circuit 1 to prevent it from being used
7. Pressure controller (proportional element or proportional-integral element) that operates to eliminate the pressure deviation leaving the dead band circuit 17
18. This is an adder 5 for adding the signal of the pressure controller 18 to the output signal of the load controller (proportional-integral element) 4.

The operation and effects of this embodiment will be explained based on FIG. 1. If a large load change rate is imposed on the gas turbine 14 during load control in a state where there is no fluctuation in gas pressure, the fuel gas generation section 12 will be unable to follow the fuel control of the gas turbine 14, and the gas pressure will increase. If the pressure deviation exceeds the dead band width of the dead band circuit 17, this pressure deviation is input to the pressure controller 18, a pressure control signal is input from the pressure controller 18 to the adder 45, and the output of the load controller 4 is input to the adder 45. is added to the signal and the load controller 4
It works to cancel the signal of

Due to the operation of this pressure controller 18, the low value priority device 1
The fuel gas control signal given from 1 to the fuel control valve 13 changes from a signal only for load control to a control signal that also takes pressure into account, and changes so as to suppress the pressure within a specified value. Thereafter, when the pressure deviation returns and the output of the pressure controller 18 disappears, the load control returns to the original load control using only the load controller 4 and continues the load control.

Through the above operations, even if the pressure deviation becomes large during a load change, the load control is continued and the fuel control valve opening command is corrected to be appropriate to eliminate the pressure deviation, resulting in smooth operation. Load control operation is realized.

Next, a second embodiment will be explained with reference to FIG. in this case,
In the speed load control section 32, a low value priority device 61 is used after the load controller 4 instead of the adder 45. The components other than the low value priority device 61 are the same as in FIG. In the case of this embodiment, if the fuel gas pressure falls below the specified value while opening the fuel control valve 13 due to load control,
The signal from the pressure controller 18 is passed to the low value priority device 6 so that the fuel control valve 13 is controlled by the signal from the pressure controller 18 with priority over the load control command (output from the load controller 4).
Select via 1.

Next, a third embodiment will be explained with reference to FIG. This is a method in which the speed load control section 33 switches between load control and pressure control using the switching circuit 19 to change load control to pressure control.

This switching is a command from the switching selection circuit 20, and the switching circuit 19 selects whether to use the signal from the load controller 4 or the signal from the pressure controller 18 for gas turbine control. You can use the switching selection circuit 19 to manually select either load control or pressure control, or when the pressure fluctuates abnormally and load control is no longer possible and you want to switch to pressure control, the pressure is automatically controlled due to a large pressure deviation, etc. Use it as if it were a choice.

Next, a fourth embodiment will be explained with reference to FIG.

The first to third embodiments described above are switched upstream of the speed control system of the gas turbine, that is, the so-called governor part consisting of the speed deviation calculation part (component 7° 52, 5 in FIG. 1) and the speed controller 10. Alternatively, a selection circuit has been provided to perform cooperative control or switching selection control between the load controller 4 and the pressure controller 18. The method described here is to switch between load control and pressure control in the speed load control section 34 on the downstream side of the speed controller 10.
This is a method of realizing this using the selection switching circuit 21 having the addition, low value priority, and switching functions described in FIGS.

The purpose of performing selection switching not on the secondary side of the load controller 4 but on the downstream side of the speed controller 10 is that even if the pressure of the gas turbine 14 is completely controlled by the signal from the pressure controller 18 as in the third embodiment, This is because if the speed control system is located later, the signal to the fuel control valve 13 may fluctuate due to the influence of the governor signal, and stable pressure control may not be possible.

According to this method, more stable pressure control can be expected than in the first to third embodiments.

〔Effect of the invention〕

As explained above, according to the gas turbine control device according to the present invention, the gas generation capacity (followability) of the fuel gas generation equipment
Even in cases where the fuel gas pressure and gas turbine load are unfavorable, adding a function to the gas turbine control device to coordinately control the fuel gas pressure and the gas turbine load greatly improves operational reliability and economic efficiency.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a first embodiment of the present invention, Fig. 2 is a system diagram showing a second embodiment, Fig. 3 is a system diagram showing a third embodiment, and Fig. 4 is a system diagram showing a third embodiment. FIG. 5 is a system diagram showing the conventional gas turbine control method. 1...Load setter 2.42.52...Subtractor 3...Load signal 4...Load controller 5.45...Adder 6...Temperature control section 7...Speed setting device 8...Speed signal 9...Start control section 10...Speed controller 11, 61...Low value priority device 12...Fuel gas generation section 13...Fuel control valve 14...Gas turbine 15...Pressure setting device 1G...Pressure signal 17...Dead band circuit 18...Pressure controller 82...Combustor agent Patent attorney Nori Chika Ken Yudo Daishimaru Ken L-----+++ J L =−−−−−m−−−−J 1− ++ ++ −−−+11 “ノ

Claims (1)

[Claims] In a gas turbine control device that controls the flow rate of fuel gas supplied to a combustor of a gas turbine using a fuel control valve,
Under normal conditions, the speed and load of the gas turbine are controlled so that they approach their respective predetermined values, and only when the pressure on the upstream side of the fuel control valve for the fuel gas fluctuates by more than a predetermined range, the pressure is returned to within the predetermined range. A gas turbine control device characterized by controlling.