JPH09250305A - Turbine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably supply a required quantity of control oil to the driving part of a steam regulating valve for controlling a turbine. SOLUTION: A HPCI starting command signal is given to the inlet end of an OR circuit 15. A test signal from an operational switch for test is given to the input end of the OR circuit 15. In the OR circuit 15, when conditions are satisfied, a starting signal is output to an auxiliary oil pump through an AND circuit 16 and an OR circuit 17. A delivery pressure low signal of a main oil pump through a pressure switch is given to the input end of an OR circuit 18. In the OR circuit 18, when conditions are satisfied, an output signal is input to the AND circuit 16, and a starting signal is output to the auxiliary pump through the OR circuit 17. When the delivery pressure low signal of the main oil pump is output, a starting signal to the auxiliary oil pump is retained by a self-holding circuit 20 equipped with a canceling circuit 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine, and more particularly to a turbine control device suitable for maintaining stable speed control in a steam turbine that requires rapid start, which is liable to cause transient changes.

[0002]

2. Description of the Related Art For example, a high-pressure water injection system is provided as a back-up device for a reactor isolation cooling system that operates during reactor isolation in a boiling water nuclear power plant. This high-pressure water injection system (hereinafter referred to as HPC
(I system) is located in the condensate storage tank that drives a small turbine-driven pump using steam generated from the reactor when the reactor is isolated and heat cannot be removed from the main turbine system. It is an important device intended to urgently supply makeup water to the reactor to remove heat.

In order to send a sufficient amount of water within a specified time (25 seconds), the turbine working in such an emergency needs to be rapidly raised to a rotational speed at which the pump rated discharge flow rate can be maintained. The steam system and the lubricating oil system of the turbine used in this HPCI system are configured as shown in FIG. That is, the steam sent from the main steam pipe (not shown) is electrically driven by the inlet valve 2 provided at the inlet of the turbine 1.
Through to the turbine 1. When steam is not supplied, the inlet valve 2 is normally closed, and the turbine 1 remains stopped due to the cutoff of steam. A hydraulically driven main steam stop valve 3 and a hydraulically driven steam control valve 4 are provided between the turbine 1 and the inlet valve 2. Normally, the main steam stop valve 3 and the steam control valve 4 are also closed.

Further, a main oil pump 5 directly connected to the drive shaft of the turbine 1 as an oil pump for supplying lubricating oil of the turbine 1 and control oil for driving the main steam stop valve 3 and the steam control valve 4, and an electric motor drive An auxiliary oil pump 6 is provided. Further, a check valve 7 is provided on the discharge pipe of the main oil pump 5, and a check valve 8 is provided on the discharge pipe of the auxiliary oil pump 6. In addition,
In the figure, reference numeral 9 is a makeup water pump for supplying makeup water, numeral 10
Indicates an oil tank.

By the way, the turbine 1 in the HPCI system
Is in a standby state at normal times as described above, but when the water level in the reactor drops, the turbine 1 immediately starts to start. When the start command is issued, an inlet valve open signal is input to the electrically driven inlet valve 2 and an auxiliary oil pump start signal is input to the auxiliary oil pump 6, and the inlet valve 2 is slowly opened. At the same time, the auxiliary oil pump 6 is also activated, the lubricating oil and the control oil are supplied, and the hydraulic pressure is established. With the establishment of this hydraulic pressure, the hydraulically driven steam stop valve 3 and steam control valve 4 start to open, and steam flows into the turbine 1 through the inlet valve 2, the main steam stop valve 3 and the steam control valve 4.

Therefore, the turbine 1 starts to rotate and reaches the rated flow speed rotation speed within a specified time. As the rotation of the turbine 1 rises, lubricating oil and control oil are also supplied from the main oil pump 5 directly connected to the drive shaft of the turbine 1. When the discharge pressure of the main oil pump 5 becomes equal to or higher than the specified pressure, a pressure switch (not shown) is activated, whereby the auxiliary oil pump 6 driven by the electric motor is stopped, and thereafter the main oil pump 5 supplies the lubricating oil and the control oil. It is supposed to be supplied.

During this operation, when the rotational speed of the turbine 1 decreases and the discharge pressure of the main oil pump 5 decreases to a specified pressure,
The pressure switch is activated to automatically start the auxiliary oil pump 6 driven by the electric motor, and the lubricating oil and the control oil are supplied to the auxiliary oil pump 6.
Supplied from

FIG. 3 shows changes in the opening degree of the steam control valve 4, the turbine speed and the control oil pressure at the time of startup. The speed control device operates immediately after the turbine 1 starts rotating, and the control state is entered only after calculating the deviation between the rotation speed of the turbine 1 and the set rotation speed. Therefore, the control oil is supplied from the auxiliary oil pump 6 to the drive unit (oil cylinder) of the steam control valve 4, and the steam control valve 4 which is fully opened flows a large amount of steam into the turbine 1 in an uncontrolled state. Temporary rotation speed rises sharply.

However, after a slight time delay, the steam control valve 4 is fully closed and operates to control the overspeed of the turbine 1. The rotation speed of the turbine 1 in which steam has stopped flowing decreases, but from the time when the actual rotation speed drops below the set rotation speed, the speed control device calculates the deviation between the actual rotation speed and the set rotation speed, and this time. The steam control valve 4 is suddenly opened to operate so as to prevent the rotation speed from decreasing. Then, thereafter, the turbine 1 continues to rise according to the set rotation speed, and finally reaches the rotation speed at which the rated flow rate is maintained.

[0010]

When the rotational speed of the turbine 1 rapidly increases as described above, the turbine 1
The main oil pump 6 of the drive shaft supplies the control oil to the drive unit of the steam control valve 4, and the auxiliary oil pump 5 automatically stops at this time. After that, the steam control valve 4 is fully closed, and the rotation speed of the turbine 1 drops. Therefore, it is necessary to open the steam control valve 1 in a short time to operate so that steam flows into the turbine 1.

At this time, since the rotational speed of the turbine 1 temporarily drops, the pressure of the control oil from the main oil pump 5 also drops, so that the auxiliary oil pump 6 automatically starts its operation. In some cases, sufficient control oil pressure cannot be maintained by various controls, and it may not be possible to ensure the oil pressure required to open the steam control valve 4. For this reason, since the steam control valve 4 gradually opens as the control oil pressure rises, it takes time to reach the rated flow rate, and as a result, the determined starting time may not be satisfied.

The transition at the time of starting is shown in FIG. As shown in the figure, it takes a long time for the control oil pressure to be established, which may exceed the specified time for starting.

Further, the auxiliary oil pump 6 is automatically started by detecting the control oil pressure, that is, the discharge pressure of the main oil pump 5 with a pressure switch (not shown). The auxiliary oil pump 6 cannot be automatically started, and in the worst case, control oil is lost to the drive unit of the steam control valve 4, and the turbine 1 cannot be started without opening the steam control valve 4.

On the other hand, since the HPCI system turbine 1 is used in an emergency such as when the reactor is isolated, it is in a standby state during normal operation of the plant, and a periodic start-up test or a regular start-up test is performed to confirm a reliable start-up function. A start-up test at the time of inspection is required.

These start-up tests are carried out by actually operating the turbine 1, but the start-up is performed manually by simulating the time of reactor isolation, so that the original start-up state at the time of reactor isolation is ensured. It is a little difficult to reproduce. That is,
According to the conventional starting method, at the time of the starting test, the operation switch of the electrically driven inlet valve 2 and the starting switch of the electrically driven auxiliary oil pump 6 are simultaneously operated to start the test. It is impossible to operate at the same time exactly as the HPCI start-up command signal, which is an electric start-up signal when the reactor is isolated, and either the inlet valve 2 or the auxiliary oil pump 6 can be operated due to the difference in operation timing between the two. However, there is a disadvantage that the time required from startup to reaching the rated flow rate changes each time the test is performed.

Therefore, an object of the present invention is to provide a turbine control device capable of stably supplying the necessary control oil to the drive unit of the steam control valve for controlling the turbine.

Another object of the present invention is to provide a turbine control device capable of confirming the start-up characteristics of a turbine by accurately simulating the time of reactor isolation during a start-up test that is carried out periodically or during a periodic inspection. is there.

[0018]

The present invention comprises a main oil pump directly connected to a drive shaft of a turbine, and an electrically driven auxiliary oil pump. The auxiliary oil pump is provided immediately after the turbine is started and before the oil pressure of the main oil pump is established. The control oil boosted by the oil pump is supplied to the drive unit of the steam control valve, and when the hydraulic pressure of the main oil pump is established thereafter, the control oil boosted by the main oil pump is supplied to the drive unit of the steam control valve. When a signal of either the HPCI start command signal or the test signal and the main oil pump discharge pressure low signal are received, a starting circuit that outputs an auxiliary oil pump starting signal to the auxiliary oil pump is provided. In addition, the starting circuit further includes a timer for holding the auxiliary oil pump starting signal for a predetermined time after the discharge pressure of the main oil pump is established.

Preferably, the auxiliary oil pump starting circuit receives an inlet valve opening signal to the inlet valve and auxiliary oil to the auxiliary oil pump when an HPCI start command signal or a test signal is input. A logic circuit that simultaneously outputs a pump start signal is provided.

[0020]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG.

The inlet valve open signal, the HPCI start-up command signal, and the test signal supplied from the test operation switch via the release circuit 12 are applied to the input terminal of the OR circuit 13. When the condition according to the logical sum is satisfied, the OR circuit 13 outputs an open signal to the electrically driven inlet valve 2.
In addition, the test signal from the test operation switch is the timer 1
The signal is output to the canceling circuit 12 via 4 and the test signal is canceled after the set time has elapsed.

Further, the HPCI start command signal is applied to the input terminal of the OR circuit 15 together with the test signal from the test operation switch. In the OR circuit 15, when the condition according to the logical sum is satisfied, a start signal for the auxiliary oil pump 6 is output via the AND circuit 16 and the OR circuit 17.
Further, the automatic operation signal of the auxiliary oil pump 6 is input to the input end of the AND circuit 16, and when the condition is satisfied according to the logical product, the start signal for the auxiliary oil pump 6 is output.

On the other hand, a low discharge pressure signal of the main oil pump 5 given from a pressure switch (not shown) is applied to the input end of the OR circuit 18. Then, when the condition according to the logical sum is satisfied in the OR circuit 18, this output signal is
A starting signal for the auxiliary oil pump 6 is output via the OR circuit 17 to the input terminal of the auxiliary oil pump 6.

Further, when a low discharge pressure signal of the main oil pump 5 is output, a self-holding circuit 20 having a release circuit 19 is provided.
Holds the start signal to the auxiliary oil pump 6. The release signal from the timer 21 is input to the release circuit 19,
The start signal from the self-holding circuit 20 is cut off. Note that reference numerals 22, 23 and 24 denote knot circuits.

Next, the operation of the above configuration will be described. First, the operation during reactor isolation will be described. In the standby state of the turbine 1, the main oil pump 5 directly connected to the drive shaft of the turbine 1 is also in the stopped state while the turbine 1 is stopped, and the main oil pump discharge pressure low signal given from the pressure switch is held. , Electric drive auxiliary oil pump 6
Is also in the stopped state, and the auxiliary oil pump automatic start signal is input to the AND circuit 16 together with the main oil pump discharge pressure low signal.

Here, when the reactor is isolated and the HPCI start-up command signal is input, the condition is satisfied in the OR circuit 13 and the inlet valve 2 is opened. At the same time, the condition of the HPCI start-up command signal is satisfied by the OR circuit 15, and its output is input to the AND circuit 16. As a result, the AND circuit 16 satisfies the condition, and the auxiliary oil pump 6 is started via the OR circuit 17. By starting the auxiliary oil pump 6, the control oil flows into the steam control valve 4, and the main steam flows into the turbine 1. Therefore, the impeller rotates in the turbine 1, the main oil pump 5 directly connected to the drive shaft starts, and the control oil pressure rises.

As the discharge pressure of the main oil pump 5 increases, the main oil pump discharge pressure low signal output from the pressure switch is cut off, but the self-holding circuit 20 starts the start signal during the set time of the timer 21. Is maintained, the operation of the auxiliary oil pump 6 is not stopped, and the control oil is continuously supplied from the auxiliary oil pump 6 to the steam control valve 4. At this time, the main oil pump 5 is also in operation, and the control oil from the main oil pump 5 is also supplied at the same time. However, due to the functions of the check valves 7 and 8 provided in the discharge pipes, respectively The control oil discharged from the pump with the higher pressure is preferentially supplied.

Even if the rotational speed of the turbine 1 is lowered and the discharge pressure of the main oil pump 5 is lowered for some reason during the startup of the turbine, the auxiliary oil pump 6 is operating and the steam control The control oil required to drive the valve 4 can be stably supplied.

After that, when the set time of the timer 21 has elapsed, a release signal is input to and output from the release circuit 19, the start signal to the auxiliary oil pump 6 by the self-holding circuit 20 is cut off, and the auxiliary oil pump 6 is stopped. To do.

It is natural that the set time of the timer 21 includes a time accompanied by a transient change at the time of starting the turbine, but it is desirable to allow a time to reach the pump rated discharge flow rate with a margin. .

Thus, when the reactor is isolated, the control oil required can be stably supplied to the drive portion of the steam control valve 4 until the rated discharge flow rate of the makeup water pump is reached.

On the other hand, when performing the start-up test, the test signal is input to the OR circuit 13 by the test operation switch. In the OR circuit 13, the condition is satisfied by the test signal, and the inlet valve 2 starts to open. 1 for electrically driven inlet valve 2
Since the opening is performed by inputting the signal twice, when the set time of the timer 14 has passed after the start-up, the release signal is output to the release circuit 12 and the test signal is cut off.

The same test signal is input to the OR circuit 15, and is input to the AND circuit 16 when the condition thereat is satisfied. As in the case of reactor isolation, while the turbine 1 is on standby, the auxiliary oil pump automatic start signal from the auxiliary oil pump 6 start switch, the main oil pump discharge pressure low signal given from the pressure switch is held, and the test signal is input. When this is done, the condition is satisfied in the AND circuit 16, and a start signal is output to the auxiliary oil pump 6 via the OR circuit 17 to start the auxiliary oil pump 6.

The operation after starting the auxiliary oil pump 6 is the same as when the HPCI start command signal is given at the time of reactor isolation, and the description thereof will be omitted.

Thus, in the present embodiment, the opening operation of the inlet valve 2 and the start of the auxiliary oil pump 6 can be performed at the same time in the starting test at the time of periodical inspection or at the time of the periodic inspection, and the turbine as in the conventional case can be obtained. The starting characteristics of No. 1 do not change from test to testing, the starting characteristics of the turbine 1 during reactor isolation can be accurately predicted, and equipment that is inconvenient for quick start conditions can be easily identified. It becomes possible to do.

[0036]

As described above, according to the present invention, the timer for holding the auxiliary oil pump start signal is provided in the starting circuit of the auxiliary oil pump only for a certain time after the discharge pressure of the main oil pump is established. It is possible to continuously and stably supply the control oil required to the drive unit of the steam control valve until the rated discharge flow rate of the makeup water pump for reactor isolation is reached.

Further, according to the present invention, when either one of the HPCI start command signal and the test signal from the test operation switch is input, the inlet valve open signal to the inlet valve and the auxiliary oil pump start to the auxiliary pump are started. Since a logic circuit that outputs signals at the same time is provided, the start-up characteristics of the turbine can be accurately confirmed through regular start-up tests, and the inconvenience caused by the combination with incompatible equipment due to the selection of equipment suitable for rapid start-up Can be prevented in advance.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a control device for a turbine according to the present invention.

FIG. 2 is a system diagram showing a conventional turbine steam system and lubricating oil system.

FIG. 3 is a steam control valve opening degree at turbine startup (normal time),
The graph which shows changes, such as turbine speed.

FIG. 4 is a graph showing changes in the steam control valve opening degree, turbine rotation speed, etc., at turbine startup (when nonconformity occurs).

[Explanation of symbols]

 1 Turbine 2 Inlet valve 4 Steam control valve 5 Main oil pump 6 Auxiliary oil pump 12, 19 Release circuit 13, 15, 17, 18 OR circuit 14, 21 Timer 16 AND circuit 20 Self-holding circuit

Claims (2)

[Claims] 1. A main oil pump directly connected to a drive shaft of a turbine, and an electrically driven auxiliary oil pump, wherein the auxiliary oil pump boosts pressure immediately after starting the turbine and before establishing hydraulic pressure of the main oil pump. The control oil is supplied to the drive unit of the steam control valve, and when the hydraulic pressure of the main oil pump is subsequently established, the control oil boosted by the main oil pump is supplied to the drive unit of the steam control valve. In this case, a starting circuit that outputs an auxiliary oil pump starting signal to the auxiliary oil pump when receiving both signals of the HPCI starting command signal and the test signal and the main oil pump discharge pressure low signal A control device for a turbine, further comprising a timer for holding the auxiliary oil pump start signal for a predetermined time after the discharge pressure of the main oil pump is established in the starter circuit. Place. 2. The turbine is provided with an electrically driven inlet valve in a main steam path, and when the starting circuit of the auxiliary oil pump receives any one of the HPCI start command signal and the test signal, The turbine control device according to claim 1, further comprising a logic circuit that simultaneously outputs an inlet valve open signal to the inlet valve and the auxiliary oil pump start signal to the auxiliary oil pump.