JPS60522B2 - steam turbine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam turbine control system, and more particularly to an improvement in return control when restarting a moving steam control valve and an intercept valve after they are suddenly closed during a system accident.

Generally, in a reheat steam turbine, a main steam stop valve and a steam control valve are provided at the inlet of the high-pressure turbine, and an intercept valve and a reheat steam stop valve are provided at the inlet of the intermediate-pressure turbine. .

The steam control valve controls the amount of steam flowing into the turbine, and the intercept valve is fully open during steady operation, but when the rate of increase in rotation of the turbine is rapid and large, such as when the power generation load is interrupted or interrupted, the intercept valve is fully open. It acts to prevent steam from entering the closed intermediate pressure turbine. These steam control valves and intercept valves are generally interlocked. A conventional control device for controlling such a steam control valve and an intercept valve is shown in FIG.

In the figure, a speed relay device 101 is driven by a signal S from a governor that detects the turbine rotation speed, a signal S2 from a synchronizer that sets the rotation speed and turbine output, and a signal S3 from a load limiter. to form a speed signal commensurate with the turbine output. The output of this speed relay device 101 passes through a low value priority device 102, and one of the outputs passes through a second
The speed relay device 103 controls the steam regulating valve through the reducing valve oil cylinder. On the other hand, the output of the speed relay device 101 is transmitted to the dashpot 111 and the intercept valve relay device 112.
, and controls the intercept valve via the intercept valve oil cylinder 113. Load detection devices 121 and 122 are provided in the control valve oil cylinder 104 and the intercept valve oil cylinder 113, respectively, and an imbalance signal S5 is provided to detect an imbalance between the turbine output and the generator load when the load is interrupted.
This operates to quickly close the steam control valve and intercept valve. In addition, the load detection devices 121 and 122 are
EVA (Earl
yValveActuation) signal S4 to quickly close the steam control valve and the intercept valve.

When the system fault is removed, the load detection devices 121 and 122 are reset by the EVA return signal S, and the steam control valve and intercept valve are restarted. At this time, the turbine output is returned to the value before the system fault occurred. It is also desirable to suppress the value to a slightly lower value in order to prevent overshoot. Therefore, the low value priority device 1
31 to operate the inlet steam pressure regulator 133 to suppress the opening degrees of the steam control valve and the intercept valve. However, the relationship of each valve to the speed relay device is as follows: As shown in Figure 2, the intercept valve is far ahead, and as shown in Figure 3, the turbine output overshoots. I will explain in detail.EVA
When the signal S4 is reset (when the return signal S4' is generated), the main steam pressure transmitter 132 detecting the main steam pressure signal S7 sends a signal corresponding to the steam pressure because the main steam pressure does not decrease. It is sent to the low value priority device 131. On the other hand, the low value priority device 131 receives a return signal S4' for controlling the opening degree of the steam control valve.
′ is given priority. The output of this device 131 drives an inlet steam pressure regulating device 133, and this regulating device 133
sends a signal to limit the opening of the steam control valve. This signal is given priority over the signal from the speed relay device 101 by the low value priority device 102 to control the steam control valve. At this time,
As mentioned above, the intercept valve fully opens in advance, but
The reheater maintains a steam pressure equivalent to the turbine output before sudden closing, and this steam flows into the medium and low pressure bin and exceeds the steam flow rate controlled by the steam control valve, so the turbine output is It overshoots as shown by the dotted line in the figure. This overshoot will disappear after a certain amount of time due to the time constant of the reheater, and the output will return to the desired value, but it is undesirable for such a situation to occur because the system is also in turmoil due to an accident. . This invention has been made in an attempt to eliminate the above-mentioned drawbacks, and provides a steam turbine control device in which stable turbine output can be expected without overshooting even when the steam control valve and intercept valve are restarted after sudden closing. The purpose is to

In order to achieve this object, the present invention provides a steam turbine control device that operates a steam control valve that controls the amount of steam flowing into the turbine and an intercept valve that operates when the turbine trips in conjunction with each other. The relationship adjustment of the steam control valve and the intercept valve after the turbine returns is restricted independently, and the opening degree of the inkcept valve is made to follow the steam control valve.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 4 shows an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same objects. According to the figure, the EVA signal S4 (or return signal S4') is sent to the low value priority device 131 via the arithmetic device 401, and
The signal is sent via the relay device 402 to the low value priority device 403 provided between the intercept valve relay device 112 and the intercept valve oil cylinder 113. Here, the arithmetic unit 401 outputs the return signal S4' for steam control valve control to the low value priority device 1.
31, and since the flow rate of the intercept valve changes depending on the steam pressure of the reheater, that is, the load before EVA operation, a signal corresponding to the required intercept valve opening is transmitted to the relay device 402 by the signal S6 corresponding to the reheat steam pressure. Send to. The relay device 402 is for amplifying this signal and after this amplification supplies the signal to the low value priority device 403 . The low value priority device 403 compares this return signal with a signal common to the steam control valve control supplied from the dashpot 111 side, but the return signal from the relay device 402 side takes priority, and the intercept valve Since it is opened in response to a low pressure value, it is restarted following the steam control valve function to a certain extent, as shown in FIG. Therefore, the turbine output can also be prevented from overshooting. Next, the main parts of the above embodiment will be explained in detail.

Figure 6 shows the low value priority device 403 and the intercept valve oil cylinder 11.
3, an intercept valve 600, and a relay device 402 are shown. Here, the intercept valve oil cylinder 113, the intercept valve 600, etc. constitute an intercept valve control device implemented from the slave, and the auxiliary closing relay 17, the spool valve 18, the intercept valve oil cylinder 113, and the intercept valve 600.The auxiliary closing relay 17 has a piston 17a and a spring 17b, and is connected to the end of the rod 501 that transmits the signal from the intercept valve relay device 112 or in the middle of the turn lever 16.The piston 17 has a piston 17a and a spring 17b. 17a is connected to a piston 18p of a spool valve 18, and control oil is introduced into the lower chamber of the piston 17a during steady operation.The spool valve 18 prompts oil supply to the inkcept valve oil cylinder 7. A number of boats 18a to 18f are provided.Boat 18a is for external refueling, boats 18d, 18e,
18f is for drain, boats 18b and 18c are for oil cylinder 113
It is for refueling. The intercept valve oil cylinder 113 has a piston 7b and a spring 7c, and drives the intercept valve 600 via rods 14 and 15. The movement of the rod 14 driven by the oil cylinder 113 is transmitted to one end 16b of the return lever 16 via the rod 19, the single support lever 20, and the rod 21. The relay device 402 includes a bellows chamber 30, a pilot 35, and a piston 36, and a diaphragm 30b of the bellows chamber 30 has a rod 31.
is connected to the rod 31, and a one-side support lever 32 is connected to one end of the rod 31. A rod 33 is attached to the lever 32.
A lever 34 is connected to the rod 41, and a rod of a piston 35p of a pilot 35 is connected to the middle of the lever 34. The rod 41 is integrally connected to a rod 37 of a piston 36 that cooperates with the pilot 35 , and one end of this rod 37 is connected to one end of the single-support lever 38 . A stopper 40 is provided at the tip of a rod 39 supported midway on this lever 38 to limit movement of the return lever 16. This stopper 40 functions as a low value priority device 403. This type of intercept valve control system operates as follows.
First, the operation during steady operation will be explained.

When a signal is given by the intercept valve relay device 112 to open the intercept valve 600, the rod 50 is driven upward, so that the return lever 16 rotates about the end point 16b. At this time, a load detection device 122 is installed at the bottom of the piston 17a of the auxiliary closing relay 17.
Control oil is supplied according to the command of relay 1.
7 is a spool valve 18 in which the cylinder and piston are integrated.
Pull up the piston blade 8P to open the boat 18b. Therefore, the control music that had been supplied through the T-boat 18a is supplied into the cylinder 7 of the intercept valve oil cylinder 113.
This supply of control oil drives the piston 7b of the oil cylinder 113 downward, and the rod 14 connected to this piston 7b,
15 moves, the intercept valve 600 is driven upwardly into an open state. Also, the piston 7 of the oil cylinder 113
The movement of the rod 14 in conjunction with the movement of b is caused by the movement of the rod 19,
The force is transmitted to the return lever 16 via the lever 20 and rod 21, and the lever 16 operates with the end point 16a as a fulcrum until the boat 18b of the spool valve 18 is closed. In this way, the piston 7b of the oil cylinder 113 and the intercept valve 600
The position (sensitivity) is proportional to the input signal. Further, when a signal is given to close the intercept valve 600 by the intercept valve relay device 112, the rod 50 is driven downward and the return lever 16 is moved to the end point 1.
It rotates around 6b as a fulcrum.

For this reason, the piston 18p of the spool valve 18 is driven downward, and the boats 18b and 18c are moved to the respective drains 18d.
, 18e, and the oil above the piston 7b of the oil cylinder 113 is discharged through the spool valve 18. At this time, the piston 7b of the oil cylinder 113 is
The intercept valve 600 is driven upward by the force c.
As the rods 19 and 2 move downward to the closed state, the rods 19 and 2
0, 21, and the action of the return lever 16, the piston 18p of the spool valve 18 returns to its original position and becomes stationary. Furthermore, when suddenly closing the intercept valve such as when the load is interrupted or during EVA, the control oil at the bottom of the piston 17a of the auxiliary closing relay 17 is removed at once, and the spool valve 18 itself is moved downward together with the piston 17a. This allows the intercept valve 600 to be suddenly closed.

Next, a description will be given of the return operation after each valve is suddenly closed.

The return signal from the arithmetic device 401 is introduced into the bellows chamber 30 of the relay device 402, and the bellows 30b of the bellows chamber 30 moves to a position where the force of the spring 30a and the air pressure are in equilibrium. This movement of the bellows 30b is caused by a series of rods 31
, the single support lever 32, the rod 33, and the return lever 34, and are transmitted to the piston 35p of the pilot 35. Here, if the piston 35p of the pilot 35 moves upward, the piston 35p opens the boat 35c, which is fitted in the lower chamber of the piston 36, toward the drain, while the boat 35d, which is fitted in the upper chamber of the piston 36, opens toward the drain side.
For opening, control oil flows into the upper chamber of the piston 36 through the boats 35b, 35d. For this reason, the rod 37,
The lever 38 and the rod 39 work together to drive the stopper 40 to the upper position. Conversely, if the piston 35p of the pilot 35 moves downward, the oil in the upper chamber of the piston 36 is discharged from the boats 35a and 35d, and the control oil is sent from the boats 35b and 35c to the lower chamber of the piston 36. for rod 37, lever 38, rod 3
9 are interlocked to drive the stopper 40 to the lower position.
In this way, be. - A series of movements from 30b to piston 36 is made by rotating the turn lever 34 using the end 34a as a fulcrum via the rod 41, stopping the pilot 35 and the piston 36, and thus stopping the stopper 40 at a predetermined position. . As can be seen, relay device 402
drives the stopper 40 in response to a signal from the arithmetic unit 401, indirectly drives the intercept valve 600, and sets the stop position of the turn lever 16. That is, the stopper 40! has priority over the signal from the intercept valve relay device 112! The signal thus determined is transmitted to the intercept valve 60. Therefore, when returning after each valve is suddenly closed, the intercept valve 600 is driven in the fully open direction in the same manner as described above, but the degree of this is regulated by the position of the stopper 40, and as a result, as shown in FIG. characteristics can be obtained.

As described above, the present invention controls the steam control valve and the intercept valve independently when restarting after sudden closing, and also allows the intercept valve function to follow the steam control valve degree to a certain extent, thereby preventing overflow. It is possible to provide a steam turbine device that is free from chutes and can be expected to provide stable turbine output.

[Brief explanation of the drawings] Fig. 1 is a system diagram of the conventional device, Fig. 2 is a characteristic diagram of the valve opening degree,
Fig. 3 is a characteristic diagram of conventional turbine output and valve engagement, Fig. 4 is a system diagram of an embodiment of this invention, Fig. 5 is a characteristic diagram of an embodiment of this invention, and Fig. 6 is an implementation of this invention. It is an explanatory diagram of the main part of an example. 101, 103...speed relay device, 102,
131...Low value priority device, 104...Adjustment valve oil cylinder, 11
1...Dashpot, 112...Intercept valve relay device, 113...Intercept valve oil cylinder, 121,
122... Load detection device, 132... Main steam pressure transmitter, 133... Inlet steam pressure adjustment device, 401... Arithmetic device, 402...
...Relay device, 403...Low value priority device. Younger brother Z diagram Younger brother Su diagram Pig 3 competition 4 younger brother Ku diagram Bell bell diagram

Claims (1)

[Claims] 1. In a steam turbine control device that operates a steam control valve that controls the amount of steam flowing into the turbine and an intercept valve that operates when the turbine trips in conjunction with each other, a signal for controlling the steam control valve and each valve are operated in conjunction with each other. The intercept valve control system is equipped with a low value priority device that outputs the smaller value of the return signal given for the return after sudden closing. A steam turbine control device configured to control an intercept valve.