JPH0472964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a turbine bypass valve of a steam turbine generator.

[Technical background of the invention and its problems]

For example, in a geothermal power plant, main steam is supplied to multiple steam turbine generators from a common main steam pipe. The main steam pressure is controlled by a main steam pressure control valve installed in a common main steam pipe. This is to prevent water from flowing into the turbine due to a drop in main steam pressure, and to keep the main steam pressure in the main steam pipe constant. In addition, a main steam relief valve is installed on the main steam pipe to prevent damage to the turbine due to a sudden increase in main steam pressure.

FIG. 1 shows a conventional configuration of a plant in which main steam is supplied to two steam turbine generators from a common main steam pipe.

The main steam supplied from the steam source 1 has its pressure adjusted by the main steam pressure regulating valve 2, the main steam pressure detector 3, and the main steam pressure regulator 4, and then passes through the main steam pipe 5 and the main steam stop valves 6, 6. ', and flows into steam turbines 8, 8' via steam control valves 7, 7'.

Generators 9 and 9' generate electricity using the steam flowing through the steam turbines 8 and 8'.
The steam passing through 8' is condensed into water in condensers 10 and 10'.

Now, let us consider a case where both steam turbines 8 and 8' are in operation.

When the steam turbine 8 is tripped due to detection of a plant abnormality and the main steam stop valve 6 is suddenly closed, or when a sudden load reduction signal from the generator 9 causes the steam control valve 7 to be tripped.
If the main steam turbine 8 is suddenly closed, the main steam turbine 8
Since the supply to the main steam pipe 5 is abruptly stopped, the main steam pressure inside the main steam pipe 5 rises rapidly.

Although the main steam pressure detector 3 and the main steam pressure regulator 4 control the main steam pressure regulating valve 2 to prevent the main steam pressure from increasing, it is not possible to suppress a sudden increase in the main steam pressure.

As a result, the steam turbine 8' in operation is suddenly accelerated due to a sudden rise in main steam pressure, and the output of the generator 9' is suddenly increased, resulting in unfavorable operating conditions for the steam turbine generator. Further, the main steam is discharged into the atmosphere from the main steam relief valve 11, which causes environmental damage and at the same time consumes the life of the main steam relief valve 11.

[Purpose of the invention]

The present invention was made in order to eliminate the drawbacks of steam in the prior art, and it installs a turbine bypass valve that bypasses the steam turbine, so that the main steam can be used when the steam turbine is tripped, when the generator load suddenly decreases, or during normal operation. A turbine bypass valve that allows steam in the main steam pipe to flow directly into the condenser when pressure rises, thereby preventing sudden acceleration of other operating steam turbines, sudden increases in generator output, and activation of the main steam relief valve. The purpose is to provide a control device for.

[Embodiments of the invention]

The present invention will be explained based on the drawings.

FIG. 2 is a system diagram showing one embodiment of the present invention.
This figure shows a configuration in which a turbine bypass valve is installed in a plant where main steam is supplied to two steam turbine generators from a common main steam pipe.

In Figure 2, 1 to 11, 1' to 10' are the first
It is exactly the same as the figure, and the difference from FIG. 1 is that turbine bypass valves 12, 12' are added.

3 and 4 are diagrams showing an embodiment of the configuration of a control device for a turbine bypass valve according to the present invention.

In both FIGS. 3 and 4, the portion surrounded by a dashed line is the control device for the turbine bypass valve.

The valve opening degree of the turbine bypass valve 12 is controlled by the output signal of the high value priority circuit 13. The output signal of the adder 14, the generator load setting value 15, and the zero potential 24 are connected to the high value priority circuit 13. That is, the high value priority circuit 13 contains the output of the main steam pressure sudden change prevention circuit, which is composed of the generator load set value 15, the zero potential 24, and the contacts 21 and 23 of the turbine trip generator load sudden decrease detection relay RD. ,
Adder 14, main steam pressure 16, maximum main steam pressure set value 17, analog memory circuit 18, and contact 1 of turbine trip generator load sudden decrease detection relay RD
9, 20, and 22, the output of the main steam pressure rise prevention circuit is input.

When the steam turbine 8 is normally operated,
Turbine trip, generator load sudden decrease detection relay
It is in the OFF state, the b contacts 19, 20, 21 of the turbine trip generator load sudden decrease detection relay RD are in the closed state, and the a contacts 22, 23 thereof are in the open state. The output signal of the adder 14 at this time is the deviation between the main steam pressure value 16 and the maximum main steam pressure setting value 17, and is a negative value. Further, at this time, since the b contact 21 is closed and the a contact 23 is open, the output signal of the high value priority circuit 13 becomes zero potential 24, and the turbine bypass valve 12 becomes fully closed.

During normal operation of the steam turbine 8, if the main steam pressure value 16 exceeds the maximum main steam pressure setting value 17 and the output signal of the adder 14 becomes a positive value, the output signal of the high value priority circuit 13 is 14, the turbine bypass valve 12 is opened and the opening operation is continued until the output signal of the adder 14 becomes zero.

Therefore, when the steam turbine 8 is in normal operation, the main steam pressure value 16 is controlled by the turbine bypass valve 12 to the maximum main steam pressure set value 17 or less, and the influence on the steam turbine generator due to the increase in main steam pressure and the main steam It can prevent the relief valve from operating.

When the steam turbine 8 trips or the generator 9 load suddenly decreases, the turbine trip generator load sudden decrease detection relay RD turns ON, and the b contact 19 of the turbine trip generator load sudden decrease detection relay RD,
20, 21 are in the open state, and their a contacts 22, 2
3 is in the closed state. At this time, the output signal of the adder 14 is the main steam pressure value 16 and the analog memory circuit 18.
is the deviation from the output of During normal operation of the steam turbine 8, the main steam pressure value 16 is input to the analog memory circuit 18, so at the moment a turbine trip or a sudden decrease in generator load occurs,
The output signal of adder 14 becomes zero. Therefore, the output signal of the high value priority circuit 13 is equal to the generator load set value 15.
Therefore, the turbine bypass valve 12 is opened for 15 minutes of the generator load set value at the moment when a turbine trip or a sudden decrease in generator load occurs. When the steam turbine 8 is in normal operation, the generator load set value is 15.
corresponds to the amount of main steam flowing into the steam turbine 8. Therefore, at the moment when a turbine trip or a sudden decrease in generator load occurs, the turbine bypass valve 12 supplies the same amount of main steam as flowing into the steam turbine 8. Since the main steam will flow directly to the condenser 10, sudden acceleration of other steam turbines in operation, sudden increase in generator output, and activation of the main steam relief valve 11 due to a sudden increase in main steam pressure can be prevented. I can do it.

Since the generator load set value 15 is automatically lowered by the turbine trip signal and the generator load sudden decrease signal, the generator load set value 15 is gradually reduced to the generator load set value 15, and the turbine bypass valve 12 is closed accordingly. becomes.

On the other hand, the main steam pressure value 16 will gradually increase as the turbine bypass valve 12 is closed, and the output signal of the high value priority circuit 13 will be the deviation between the main steam pressure value 16 and the output of the analog memory circuit 18. The main steam pressure value 16 is controlled by the turbine bypass valve 12 to match the main steam pressure at the moment when a turbine trip or sudden decrease in generator load occurs, thereby minimizing the influence on other operating turbines. I can do it.

〔Effect of the invention〕

As explained above, the present invention installs a turbine bypass valve that bypasses the steam turbine, and allows steam in the main steam pipe to directly flow into the condenser when the steam turbine trips or when the generator load suddenly decreases. This has the effect of preventing sudden acceleration of the steam turbine during operation, sudden increase in generator output, and activation of the main steam relief valve.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing the equipment configuration of a conventional example;
The figure is a system diagram showing the equipment configuration of the present invention, and FIGS. 3 and 4 are block diagrams showing one embodiment of the present invention. 1...Steam source, 2...Main steam pressure control valve, 3...
...Main steam pressure detector, 4...Main steam pressure controller,
5... Main steam pipe, 6, 6'... Main steam stop valve, 7,
7'...Steam control valve, 8,8'...Steam turbine,
9,9'... Generator, 10,10'... Condenser, 1
1... Main steam relief valve, 12, 12'... Turbine bypass valve, 13... High value priority circuit, 14... Adder, 15... Generator load setting value, 16... Main steam pressure value, 17... ...Maximum main steam pressure setting value, 18
...Analog memory circuit, 19, 20, 21...
Turbine trip generator load sudden decrease detection relay b
Contacts, 22, 23... A contact of turbine trip generator load sudden decrease detection relay, 24... Zero potential.

Claims (1)

[Scope of Claims] 1. Main steam at a predetermined pressure is supplied from a common main steam pipe to a plurality of steam turbines through a main steam pressure control valve. A control device for a turbine bypass valve, comprising: a turbine bypass valve for guiding the main steam; (1) During normal operation, issue an opening command for the turbine bypass valve to correct the main steam pressure by the amount when the main steam pressure of the common main steam pipe exceeds a predetermined maximum main steam pressure setting value. , a main steam pressure increase prevention circuit that issues an opening command for the turbine bypass valve in order to maintain the main steam pressure at the main steam pressure value at that time in the event of a turbine trip or sudden decrease in generator load. (2) During normal operation, the opening command for the turbine bypass valve is zero, and in the event of a turbine trip or sudden decrease in generator load, the main steam amount corresponding to the generator load set value is lowered based on this condition. A main steam pressure sudden change prevention circuit that issues an opening command for the turbine bypass valve. (3) Selecting the larger opening command for the turbine bypass valve from the main steam pressure rise prevention circuit and the main steam pressure sudden change prevention circuit and outputting a signal for driving the turbine bypass valve. High value priority circuit.