JPS6321013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a two-shaft rehito gas turbine generator having an intercooler.

[Technical background of the invention and its problems]

In recent years, gas turbines have also been made to operate at higher temperatures and higher pressures in order to operate with high efficiency. As part of this effort, a two-shaft rehito gas turbine as shown in FIG. 1 is attracting attention. This consists of two shafts: a low-pressure shaft for driving the generator and a high-pressure shaft for generating gas to be supplied to the low-pressure shaft.The exhaust gas from the low-pressure shaft is circulated to the high-pressure shaft via an intercooler. This intercooler is combined with, for example, a boiler to form a combined cycle and is configured to maximize thermal efficiency.

This configuration will be explained.

A low-pressure shaft system directly connected to the generator 9 receives generated gas from the outlet of the high-pressure gas turbine 5 through a gas duct to the intermediate-pressure turbine 6 to obtain shaft driving power. This outlet gas and the cooling air mixed into this outlet gas along the way are given to a low pressure combustor (also referred to as a reburner) 7, and fuel is injected into this combustor 7 to obtain combustion gas, and a low pressure turbine 8 is generated. It is driven to generate driving power for the low pressure shaft and exhausted from the exhaust device 21. The low-pressure compressor 1 is rotated by consuming a part of this driving power, sucks atmospheric air from the intake device 20, cools the compressed air to a predetermined temperature through the intercooler 2, and then compresses the high-pressure shaft system with high pressure. Send air to machine 3. This high-pressure shaft system is composed of a high-pressure compressor 3 that functions as a gas generator, a high-pressure combustor 4, and a high-pressure turbine 5. Starting devices 10 and 11 each having an electric motor are coupled to the shaft ends of the high and low pressure shafts via speed increasing gears.

As attached devices to such main equipment, the control operation end of each equipment is the fuel flow control valve 14 of the high pressure combustor 4, the fuel flow control valve 15 of the low pressure combustor 7, and the low pressure compressor all-stage variable stator vane operating device. 13. Outlet discharge valve 1
2 is provided. In addition, there is a changeover switch to turn on a setting device that controls the transmission torque of the high-pressure system startup device according to a preset program among the sequence controls that are operated in sequence at startup, and The entire system consists of a rotation speed comparator, etc., which gives a command to fully close the bleed air discharge valve, which was fully open to avoid the surging region at startup, after the valve is activated to a sufficiently safe region.

This enables highly efficient gas turbine power generation.

However, it is difficult to control such a two-shaft rehito gas turbine, and at present no control device that can be put to practical use has been provided.

[Purpose of the invention]

An object of the present invention is to provide a two-shaft rehito gas turbine control device that has safe, reliable and reproducible start-up control characteristics and can perform load operation with high efficiency.

[Summary of the invention]

To achieve this objective, in the present invention, after increasing the rotational speed of the high and low pressure shafts using a starter device, the high pressure combustor and then the low pressure combustor are ignited, and the fuel control valves of both combustors are throttled to the minimum opening degree. After that, speed up control is performed while monitoring the speed of the high pressure shaft, then speed up control is performed while monitoring the turbine outlet temperature of the low pressure shaft, and when the predetermined speed is reached, the generator is connected to the system. The present invention provides a device that controls the low pressure shaft in response to load fluctuations and in response to turbine outlet temperature.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 10.

FIG. 2 is a block diagram showing the configuration of a two-shaft reheat gas turbine control device according to the present invention.
In this figure, the valve opening control sections 16, 18, 19 and the blade opening control section 17 shown surrounded by dashed lines are the same elements as those shown in FIG. These control units are valve or blade opening detection units 65, 6.
0, 31, 49, demodulation section 66, 61, 22, 5
0, addition/subtraction parts 67, 62, 23, 34 and servo amplification parts 64, 59, 30, 48, depending on the output of the valve or blade opening setting parts 63, 58 or position setting parts 29, 33. Controls the opening of the blades.

Control signals are applied to each of these setting sections from each element shown on the left side of FIG. 2 to control the opening of each valve or blade. This control operation will be explained in order from startup to load operation.

When the high and low pressure shafts are rotated individually by the starter device and reach the ignition rotation speed at which the air flow required for ignition is obtained, the fuel control on the high pressure combustor side is first performed by the ignition opening command from the start/stop sequential control device (not shown). An ignition flow rate set value signal from an ignition fuel setting section 78 is applied to the valve 14 via a changeover switch 76.

After the high-pressure combustor ignites, another ignition opening command causes
Similarly, the ignition flow rate setting value signal from the ignition fuel setting section 79 is applied to the fuel control valve 15 on the low-pressure combustor side via the changeover switch 32.

The high and low pressure fuel control valves 14 and 15 are controlled by the sequential control device after a predetermined period of time has elapsed from the final ignition command, and the respective valves 14 and 15 are set to the minimum opening degree via the changeover switches 76 and 32 to obtain the minimum fuel flow rate. A fuel flow setpoint signal is provided.

As a result, the high-pressure combustor 4 is first ignited, and after the ignition time for the 10 combustors has elapsed, the fuel control valve 14 is narrowed down to the minimum opening degree. Similarly, the low pressure combustor 7
After the ignition time for the 12 cans of combustor has elapsed, the fuel control valve 15 is throttled down to the minimum opening degree.

After this, when a predetermined period of time has passed, the speed setting section 46
Give the high pressure shaft actual rotation speed as the initial setting value. At the same time, the output of the acceleration setting section 40 is given to the speed setting section 46. Thereafter, the speed setting section 46 calculates a speed target value according to the high-pressure shaft actual speed/acceleration target setting curve, and provides it to the addition/subtraction section 43 via the changeover switch 77. The addition/subtraction section 43 calculates the deviation between the speed target value and the actual speed signal from the speed detection section 42 and provides it to the speed control section 41 .

The output of the control section 41 is applied to the position setting section 33 for the valve 14 as a requested high-pressure fuel flow rate signal equivalent to a speed-up control signal via a low value selection section 39 and a changeover switch 76, which will be described later.

Similarly, after a predetermined period of time has elapsed after the fuel control valve 15 of the low-pressure combustor 7 is throttled down to the minimum opening degree, the outlet temperature of the low-pressure turbine 8 is controlled. First, a target temperature setting value is given by the low pressure turbine outlet temperature setting section 24, and this setting value is applied to the addition/subtraction section 24.
At step 7, the detected value of the actual gas temperature is compared with the actual gas temperature detected by the outlet temperature detector 26, and the deviation between the two is inputted to the outlet temperature controller 25.

The output of the control section 25 is inputted to the position setting section 29 for the valve 15 as a required low pressure fuel flow rate corresponding to a low pressure turbine outlet temperature control signal via a low value selection section 28 and a changeover switch 32, which will be described later.

As a result of such control, the low pressure shaft rotation speed increases. For low-pressure shaft speed control, a constant set value is given from the speed setting section 51, compared with the detected value from the speed detection section 53 in the addition/subtraction section 54, and a deviation is taken out and inputted to the speed control section 52.

On the other hand, the set value from the load setting section 68 is given to the addition/subtraction section 71, compared with the actual output detection value of the generator output detection section 70, and the load deviation is extracted and inputted to the load control section 69 which performs proportional-integral operation. The output of this load control section 69 is given to adders 55 and 75 when governor automatic/manual selection switch 73 is in automatic mode.

This switch 73 is manually selected when starting the turbine, and the manual load setting section 74 is set to zero. Automatic selection is performed during load control after generator synchronization is added, which will be described later.

Since the signal given to the adders 55 and 75 from the manual load setting section 74 is zero at the time of startup, the output of the adder 55 is the output of the speed control section 52, and the output of the adder 75 is the output of the load setting section 74. This is the output of the bias setting section 72 and is also given to the low value selection section 56 . The load bias setting section 72 is 100% positive and negative.
The signal range is configurable and positive 100
Suppose we set a % bias. As a result, the two inputs to the low value selection section 56 take large values at startup.

On the other hand, if a value smaller than the above two inputs is given by the initial setting section 57 as the third input of the low value selection section 56, the initial setting value is output from the low value selection section 56. This initial setting value is determined to ensure that the high pressure combustor fuel control is switched from high pressure shaft speed control to low pressure shaft speed control near the rated speed. After switching, input from the initial value setting section 57 to the low value selection section 56 is canceled.

Next, in order to synchronously connect the generator to the power grid, the speed of the generator (low-voltage shaft) is adjusted to match the grid frequency. For this purpose, a uniform speed control command is given to the manual load setting section 74 from a uniform speed control device (not shown).

The low-pressure shaft speed needs to be maintained at the rated speed, for example, 3000 rpm, so the control output is input from the speed control section 52 to the addition/subtraction section 55, while the uniform speed control command is added to the addition/subtraction section 55 via the manual load setting section 74. The adder/subtractor 55 forms a superimposed signal of these signals. Since the bias setting value from the load bias setting section 72, which is another input, is set to the maximum in the low value selection section 56 to which the output of the addition/subtraction section 55 is given as one input, the speed control section 52
A signal from the side is applied to the high pressure fuel flow rate control system through the low value selection sections 56 and 39, and uniform speed control is performed.

At this time, if conditions including other synchronous joining conditions are established, the generator is synchronously joined to the power system by an automatic synchronizer (not shown).

After synchronization, governor automatic/manual selection switch 7
3 is automatically selected as the governor and the target load is set in the load setting section 68, thereby performing load increase control. That is, the detected value of the actual load detection section 70 is matched with the target load by the addition/subtraction section 71, and is inputted as a load deviation signal to the load control section 69, and a load control signal is output. This signal is added to the speed control signal, and high pressure fuel flow rate control is performed as described above.

At this time, the relationship with the other two inputs of the high voltage/low value selection section 39 is as follows. Assuming that these two inputs are not selected by the low value selection section 39, the high pressure turbine inlet temperature control section 36, which includes an integral element, follows the output of the low value selection section 39 to ensure that the integral element is saturated. To prevent. At the same time, when the control deviation of the output of the addition/subtraction section 38 is reversed to the negative side, the control signal is continuously switched in the low value selection section 39. Similarly, since the other high pressure turbine speed control section 41 does not include an integral element, the low value selection section 39
It does not follow the output of , but it is switched continuously when the minimum control output is reached. At this time, other control outputs are made to follow this selected control output in preparation for the next control system switching.

On the other hand, the low-pressure combustor fuel flow control systems 29 and 19 are continuously given the required fuel flow rate setting through the low value selection section 28 by the low-pressure turbine outlet temperature control systems 24, 25, 26, and 27 during startup and even when the load increases. However, in exceptional cases, the other load-equivalent main control signal (output of the low value selection section 56) may be selected. This is a case where the low-pressure shaft speed becomes excessive when the generator load is cut off, and the load-equivalent main control signal temporarily becomes a negative signal.

When the high-pressure side fuel and low-pressure side fuel are controlled in this way when the load increases, the low-pressure compressor outlet blow-off valve 12
Control is performed using a load-equivalent main control signal so that the main air flow rate is continuously increased by the low-pressure compressor variable stator blade as the load increases.

3 and 4 show the program settings of the valve opening degree setting section 63 and the blade opening degree setting section 58 for performing this control. In other words, when the load equivalent main control signal reaches the no-load equivalent, the low-pressure compressor outlet blow-off valve opening is 85% and the low-pressure compressor variable stator blade opening is 11°, and from the no-load equivalent to the load equivalent main control signal 30%, the outlet The blowoff valve opening degree is changed linearly from 85% to 0%, the variable stator blade opening degree remains at 11%, and the outlet blowoff valve opening degree is then 0% until the load equivalent main control signal reaches 100%.
Change the variable stator blade opening degree linearly up to 100%.

FIG. 5 shows the high pressure turbine speed bias setting section 44.
This shows the program settings for the actual load 30
increases linearly from 30% to 100%
It has the characteristic of having a constant bias value close to %.

Figure 6 shows the program setting contents of the high-pressure turbine acceleration setting section 40. The high-pressure turbine accelerates at a constant rate of 6.7 [rpm/sec] until the actual rotation speed reaches approximately 3500 rpm, and 4.8 [rpm/sec] from 3500 rpm to 4000 rpm. ] and decreases linearly to 4.8 from 4000rpm to 6300rpm.
[rpm/sec] is set to be constant, and then acceleration becomes 0 at 7000 rpm. Therefore, the acceleration changes in approximately three stages.

Figure 7 shows the program setting contents of the low-pressure turbine outlet temperature setting section 24.
It increases linearly to 607℃ at ~5400rpm, and remains constant at 607℃ at higher rotation speeds.

Figure 8 shows the high pressure turbine inlet gas temperature setting section 35.
This shows the program setting contents.In the low load area, the temperature is constant at 1000℃, and when the load equivalent main control signal is in the range of 10% to 30%, it increases linearly, and when it is over 30%, it increases linearly.
Keep the temperature constant at 1300℃.

9 and 10 show the opening setting characteristics of the fuel control valves of the high-pressure combustor and the low-pressure combustor, and the characteristics of FIG.
The characteristic is also set at 29 as a nonlinear characteristic correction function of the valve opening degree and the fuel flow rate. Although the number of valves has been described as one, it is of course possible to modify the system to include two valves in each system depending on the rangeability of the valve.

As described above, the present invention is capable of controlling a two-shaft rehito gas turbine consisting of a high-pressure shaft as a gas generator and a low-pressure shaft that drives a generator using gas from the gas generator. At the time, the speed of the high-pressure shaft is controlled according to the acceleration setting schedule, and the low-pressure shaft controls the fuel of the low-pressure combustor with the turbine outlet temperature as the target, making it possible to start up smoothly and quickly. Since the main air flow rate is continuously controlled by the variable stator vanes of the low-pressure compressor during operation, high-efficiency operation control can be performed even as partial load characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a two-shaft reheat gas turbine to which the present invention is applied, FIG. 2 is a block diagram showing the configuration of the device according to the present invention, and FIGS. FIG. 3 is an explanatory diagram of control characteristics of some main elements in the device of FIG. 2; 1...Low pressure compressor, 2...Intercooler, 3...
High pressure compressor, 4... High pressure combustor, 5... High pressure turbine, 6... Intermediate pressure turbine, 7... Reburner, 8...
...Low pressure turbine, 9 ... Generator, 10 ... Low pressure starting device, 11 ... High pressure starting device, 12 ... Low pressure compressor outlet blow-off valve, 13 ... Low pressure compressor variable stator vane operating device, 14 ... High pressure fuel flow control valve, 15...Reburn fuel flow control valve, 16...12 Valve opening (position)
Control unit, 17...Low pressure compressor variable stator blade opening (position) control unit, 18...High pressure fuel flow rate control valve opening (position) control unit, 19...Reburned fuel flow rate control valve opening (position) Control unit, 20... Intake device, 21...
Exhaust system, 22...15 valve opening detector demodulator,
23...19 addition/subtraction unit, 24...Low pressure turbine outlet temperature setting unit, 25...Low pressure turbine outlet temperature control unit, 26...Low pressure turbine outlet temperature detection unit,
27... Addition/subtraction section, 28... Reburner low value selection section, 29... Position setting section for 19, 30... Servo amplifier section for 15 valves, 31... Servo valve and opening detector for 15 valves, 32...changeover switch, 33...18
position setting section, 34...18 addition/subtraction section, 35...
...High pressure turbine inlet temperature setting section, 36... Temperature control section, 37... Temperature calculation detection section, 38... Addition/subtraction section, 39... High pressure combustor low value selection section, 40
...High pressure turbine acceleration setting section, 41... High pressure turbine speed control section, 42... Same speed detection section, 43
... Same addition/subtraction section, 44... Same speed bias setting section, 45... Same addition section, 46... Same speed setting section,
47... Same rated speed constant setting unit, 48... Servo amplifier unit for 14 valves, 49... Servo valve and opening detector for 14 valves, 50... Demodulation unit for 14 valve opening detector,
51...Low pressure turbine rated speed constant setting section, 52
...Low pressure turbine speed control section, 53... Same speed detection section, 54... Same addition/subtraction section, 55... Same addition section,
56... Same speed/load low value selection section, 57... Low pressure shaft speed switching, initial value setting section, 58... Low pressure compressor variable stator blade opening setting section, 59... Servo amplification section for 13, 60... ... Servo valve and opening detector for 13, 61
...opening detection demodulation section for 13, 62...17 addition/subtraction section, 63...low pressure compressor outlet air blow valve opening setting section, 64...servo amplification section for 12 valves, 65...1
Servo valve and opening detector for 2 valves, 66...12 Demodulation unit for valve opening detector, 67...16 addition/subtraction unit, 6
8...Load setting section, 69...Load control section, 70...
... Generator output (actual load) detection section, 71 ... Load control section addition/subtraction section, 72 ... Load bias setting section, 7
3...Governor automatic/manual selection switch, 74...
Manual load setting section, 75... Addition section for load bias setting, 76... Changeover switch, 77... Changeover switch, 78... High pressure combustor ignition fuel setting section, 79
...Reburner ignition fuel setting section.

Claims (1)

[Claims] 1. A high-pressure shaft as a gas generator, a low-pressure shaft that uses gas from the gas generator to drive a load and a compressor to form compressed air, and a a two-shaft reheat gas turbine having an intercooler that cools compressed air and supplies it to the high-pressure shaft; and a second shaft that provides a setting signal that gradually increases until the actual load of the gas turbine reaches a predetermined value and then becomes a constant value. 1 device, a second device that gives a setting signal that is low temperature until the actual load reaches a predetermined value and then becomes a constant value of a higher temperature; a high-pressure shaft control system that has a third device that gives an acceleration setting signal that is at a low rate and becomes 0 when a predetermined speed is reached, and performs fuel control based on the setting signals from the first to third devices; A first device that controls the outlet blow-off valve opening and the variable stator blade opening of the compressor on the low-pressure shaft by being given a load-equivalent main control signal following the setting signal; a second device that provides a setting signal to maintain the turbine outlet temperature of the low pressure shaft at low temperature in the high speed range and high temperature in the high speed range;
A control device for a two-shaft rehito gas turbine, comprising a low-pressure shaft control system that performs fuel control based on setting signals from the first and second devices.