JPH03242404A - Bleeding turbine control device - Google Patents

Abstract

PURPOSE:To prevent fluctuation of outlet stream pressure in a steam generator by keeping a bleed pressure control signal added to a steam regulating valve opening command in a hold condition when bleed load is in its abnormal condition. CONSTITUTION:A signal following/holding device 33 is provided between the output of a coefficient multiplier 30 and an adder 24. A bleed load abnormal switch 34 which closes when a bleed load is changed abnormally by rapid increasing, rapid reducing, and the like, is inputted from a bleed load side device, and when the switch 34 is opened, the signal following/holding device 33 is operated so that an input and an output may match each other at all times in a following mode. And when the switch 34 is closed, the device 33 is operated so that the previous value may be held. It is thus possible to hold outlet stream pressure in a steam generator at a constant level, since the opening of a steam regulating valve is held at a constant level when the bleed load is changed rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an extraction turbine control device for controlling turbine output and turbine extraction pressure in a thermal power plant.

(Conventional technology) Figure 3 shows a system diagram of a general extraction turbine.

Steam from the steam generator 1 flows into the high-pressure turbine 4 through a main steam stop valve 2 and a steam control valve (hereinafter abbreviated as C) 3. The steam that has completed its work in the high-pressure turbine 4 passes through an extraction control valve (hereinafter abbreviated as ECV) 5 and flows into a low-pressure turbine 6, and the steam that has completed its work here is discharged to a condenser 7.

On the other hand, the steam that has done work in the high-pressure turbine 4 is removed by the extraction check valve 8.
The air is sent to a bleed air load 9 such as factory equipment for use. Note that the PS 10 on the upstream side of the bleed air check valve 8 is a bleed air pressure detector.

The generator 11 is directly connected to the rotating shafts of the high pressure turbine 4 and the low pressure turbine 6.

A block diagram of a conventional control device for controlling the above turbine system is shown in FIG.

The load setting device 21 inputs signals from the load setting device switch 22 and the load setting device switch 23, and outputs a load setting value. Then, the adder 24 adds the load setting V and the signal V from the bleed pressure control to obtain the Cv opening command v3, and this signal controls the Cv opening to control the amount of steam flowing into the high pressure bin 4. Adjust.

The bleed pressure setting device 25 includes a bleed pressure setting device switch 26,
Input the signal of the bleed pressure setting range switch 27 and output the bleed pressure setting [V4. Then, the actual bleed pressure 5 detected by the bleed pressure detector 10 and the set bleed pressure v4 are input to the adder 28, and a deviation signal V between the two is output.

The deviation signal V is input to the controller 29, where it is subjected to compensation calculations such as proportionality, lead, and delay for pressure control, and is output as the bleed pressure control signal V7.

This bleed pressure control signal v7 is input to a coefficient multiplier 30, where it is multiplied by a proportional coefficient indicating the ratio at which the bleed pressure control at Cv is performed, and is output as a signal v8.

On the other hand, the amount of change in the ECV opening when the load setting value V changes is set by the coefficient multiplier 31 and output as a signal v2. The signal ν2 and the signal v7 are input to the adder 32, and the difference signal v is used as the ECV opening command and the low pressure turbine 6.
Adjust the amount of steam flowing into the

In the above control device, the turbine output is the load setting value ν
1, and when the V gear is changed, the Cv opening command v
3 and ECV opening command V change simultaneously. For example, ν
When increasing by 1, the Cv opening degree increases by the same amount. Also,
The ECV opening increases by an amount multiplied by the proportional coefficient set by the coefficient multiplier 31, and the turbine output increases linearly.

On the other hand, the bleed air pressure set value v4 is set to a constant pressure value, and Cv and ECV are set so that the bleed air actual pressure V is a constant value.
Control opening degree. For example, when the amount of extracted steam in the extracted air load 9 increases, the actual extracted air pressure V decreases, so the ECV opening degree is controlled in a decreasing direction. If you reduce the ECV opening, the amount of steam in the low-pressure turbine will decrease, so the amount of work in the low-pressure turbine will decrease, and the turbine output will drop. Therefore, at the same time, the bleed pressure control signal shift increases the C■ opening and increases the flow to the high-pressure turbine. The amount of steam is increased to prevent turbine output from decreasing.

As mentioned above, in extraction turbine control, the turbine output is set to 4! ? ! Two types of control are performed: controlling the pressure to a set value and controlling the bleed pressure to a constant value.

(Problems to be Solved by the Invention) In normal power plant control, turbine control and steam generator control are performed in a coordinated manner.

In other words, if the flow rate of steam flowing into the turbine is increased faster than the capacity of the steam generator, or if the amount of steam is changed, the steam pressure at the inlet of the turbine, that is, the steam pressure at the outlet of the steam generator, will rise or fall abnormally, making it unsafe. Therefore, it is common that the steam generator is automatically stopped. Therefore, the operator increases or decreases the load setting device 21 in accordance with the capacity of the steam generator 1.

In such a system, the operation of each part when an event such as a sudden change in the bleed air load 9 occurs is shown in FIG.

When the bleed air load suddenly increases, the bleed air actual pressure v5 decreases.

For this reason, the bleed pressure control signal v7 increases, so the ECV
The opening command V is decreased and the CV opening command V3 is increased, so that control appropriate to the bleed air load is performed without changing the output of the generator 11.

However, the movement of the steam control valve at this time is a sudden opening operation in order to respond immediately to a sudden change in the extraction load 9, and if the steam generator 1 cannot follow this sudden opening operation, the steam generator 1
The steam generator 1 is automatically stopped due to an abnormal drop in the outlet steam pressure of the steam generator 1, resulting in a problem that the operation of the power generation plant is stopped.

In the above explanation, an example was given in which the bleed air load suddenly increased, but when the bleed air load suddenly decreases, the operation is reversed, and the pressure rises abnormally, causing the steam generator 1 to automatically stop in the same way.

SUMMARY OF THE INVENTION Accordingly, the present invention aims to provide a bleed turbine control device that allows fluctuations in generator output when the bleed load suddenly changes, but prevents fluctuations in steam pressure at the outlet of a steam generator.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a signal tracking holder that inputs an external condition of a sudden change in the bleed air load and maintains the bleed air pressure control signal to be added to the CV command at the current value. It is characterized by:

(Function) With the above configuration, the CV opening degree is kept constant when the extraction load suddenly changes, and as a result, the steam pressure at the outlet of the steam generator is kept constant.

(Embodiment) FIG. 1 shows a configuration diagram of an extraction turbine control device according to an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 4 indicate the same or corresponding parts, and the difference from the configuration in FIG.
A signal follower/retainer 33 is provided between the output of the adder 24 and the adder 24. This signal follower/retainer 33 inputs the bleed load abnormality switch 34, which is closed when the bleed load undergoes an abnormal change such as sudden increase or decrease, from the bleed load side device, and when the switch 34 is open, it is always in the follow-up mode. It operates so that the input and output match, and when the switch 34 is closed, it operates so as to hold the value immediately before the switch was closed.

FIG. 2 shows the movement of each part in FIG. 1 when the bleed air load suddenly changes.

When the bleed air load increases rapidly at time t, the bleed air load abnormality switch 34 is closed at the same time. As a result, the signal follower/retainer 33 holds the signal ν1o just before time t1 constant, and C
The v opening command V remains constant.

In addition, due to the sudden increase in the bleed air load, the actual bleed pressure V5 decreases and the bleed pressure M control signal v7 increases, causing the ECV to increase.
The opening degree opening command part is decreased and the ECV opening degree is throttled to reduce the steam flow rate to the low pressure turbine, and the reduced amount is supplied to the extraction load side.

On the other hand, the generator output will sharply decrease as the ECV is throttled and the steam flow rate to the low-pressure turbine is reduced, but since the CV opening is constant, the steam pressure at the outlet of the steam generator 1 remains constant. It is possible to avoid stopping the steam generator due to abnormal changes in the temperature. Also, when the bleed air load returns to its original value at time t2, the bleed air load abnormality switch 34 opens and the signal follower/retainer 33 inputs the V value at this time.
At the same time, the actual bleed pressure V returns to its original value, so the bleed pressure control signal shift returns to its original value, and as a result, the CV opening command V
There is no change in 3.

In this way, by keeping the Cv opening constant when the extraction load suddenly changes, the outlet steam pressure of the steam generator 1 can be kept constant.

[Effects of the Invention] As explained above, according to the present invention, when the bleed air load suddenly changes, the bleed air load flow rate can be supplied by controlling only the ECV, and by keeping the CV opening constant. , the outlet pressure of the steam generator can be kept constant. As a result, it is possible to avoid stopping the steam generator due to abnormal changes in the outlet steam pressure, allowing the power plant to continue operating, and the effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a turbine control device according to the present invention;
FIG. 2 is an operational diagram of the turbine control device according to the present invention;
The figure is a general turbine system diagram, FIG. 4 is a block diagram of a conventional turbine control device, and FIG. 5 is a conventional turbine control operation diagram. 33...Signal follower/retainer, 34...Bleed air load abnormality switch (7317) Representative patent attorney Kensuke Chika (8)
869) Representative Patent Attorney Takeshi Komaru Figure 1 Figure 2 Figure 2

Claims (1)

[Claims] An air extraction system that simultaneously controls the turbine steam control valve opening and the extraction air control valve opening based on the deviation between the turbine output setting value, the turbine extraction pressure setting value, and the actual extraction pressure to output a predetermined turbine output and turbine extraction air flow rate. A bleed air turbine control device, characterized in that the bleed air turbine control device is provided with a signal follower holder that holds a bleed air pressure control signal to be added to a steam control valve opening degree command in a state where the bleed air pressure control signal is held in the case of an abnormal bleed air load.