JPH0149916B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recirculation flow rate control system in a boiling water nuclear power plant, and more particularly to improvements in means for controlling a generator for driving a recirculation pump motor.

A recirculation flow rate control device in a boiling water nuclear power plant is a device for adjusting the core flow rate by controlling the speed of a recirculation pump, thereby controlling the reactor power. This device distributes and supplies the speed request signal normally sent from the main controller to two speed control loops through a speed limiter.
actuating an actuator by a control signal sent from a speed controller in each speed control loop to adjust the scoop pipe position of a fluid coupling coupling between a drive motor and a generator for driving a recirculation pump motor; The speed of the recirculation pump is controlled by changing the rotational speed of the generator to change its output frequency, thereby controlling the speed of the recirculation pump motor. Each speed control loop is provided with a feedback system so that the speed request signal and the actual generator speed fed back from the generator are compared, and control is performed in the direction of making the deviation value zero. ing.

In the conventional device with the above configuration, when a speed increase request signal is given, the output signal of the speed controller gradually increases according to a predetermined control constant, and the generator speed increases accordingly. , the response will be delayed by that amount. Therefore, when the generator speed reaches a speed commensurate with the speed request signal, the output signal of the speed controller will exceed the target value. When the generator speed exceeds the target value and further increases, the speed control signal changes to a signal that decreases the speed, and the generator speed starts to decrease following this. After repeating these operations, the generator speed stabilizes at the target value.
That is, in the conventional system, the generator speed repeatedly overshoots and undershoots, and the overshoot of the generator speed also causes the recirculation pump to overshoot. As a result, the core flow rate becomes excessive and the reactor power increases excessively. As a result, the integrity of nuclear fuel may be seriously affected.

On the other hand, if the equipment that feeds back the generator speed in the recirculation flow rate control device malfunctions or breaks down, and the signal indicating the speed decrease is fed back during the generator speed increase control, the speed request signal and the feedback signal may become different. A large deviation will occur between the two, causing the speed controller to send a signal to rapidly increase the generator speed. As a result, reactor power increases rapidly, leading to an emergency shutdown of the reactor. In addition, the increase in reactor output would impair the integrity of the nuclear fuel.

The present invention was made in consideration of these circumstances, and its purpose is to provide a faster response than conventional ones without overshooting the rotational speed of the generator for driving the recirculation pump motor relative to the target value. In addition to being able to control speed, even if feedback system equipment malfunctions or breaks down, it can prevent a sudden increase in generator speed, eliminating the need for emergency reactor shutdown operations and maintaining the integrity of the nuclear fuel. It is an object of the present invention to provide a nuclear reactor recirculation flow rate control device that can perform extremely safe and stable control.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. In the figure, steam generated in a reactor pressure vessel 1 is sent to a turbine 3 through a main steam pipe 2, and is converted into electrical energy by a main generator 4 rotationally driven by the turbine 3. After driving the turbine 3, the steam is condensed in a condenser 5 and then returned to the reactor pressure vessel 1 by a reactor feed water pump 6. A pressure regulator 7 provided near the inlet of the turbine 3 receives a turbine inlet pressure signal from the main steam pipe 2 and a load signal from the turbine 3, and sends a load request signal SO to the recirculation flow rate control device 8.
send.

The recirculation flow rate control device 8 operates based on the load request signal SO etc. from the pressure regulator 7, and ultimately controls the recirculation pump 1 provided in the recirculation system 9.
The reactor output is controlled by controlling the zero speed and controlling the recirculation flow rate, that is, the core flow rate, and is configured as follows.

The main controller 11 outputs the load request signal SO from the pressure regulator 7 or a signal formed by its own manual operation as the speed request signal S11. The speed request limiter 12 functions so as not to pass the speed request signal S11 that is lower than a set value. The signal passing through the speed demand limiter 12 is distributed and supplied to two speed control loops. Since each speed control loop has exactly the same configuration, only one is illustrated in this embodiment. Manual and
Automatic switching device (hereinafter abbreviated as M/A switching device) 13
When switched to the automatic side, the signal S12 that has passed through the speed request limiter 12 is sent directly to the speed limiter 14, and when switched to the manual side (when the signal S12 does not come, etc.) , the signal formed by their own manual operation as the speed request signal S13
Output as . The speed limiter 14 outputs a signal corresponding to the minimum speed of the recirculation pump as the speed request signal S14, regardless of the speed request signal S13, when the water supply flow rate by the water supply pump 6 is less than 20% of the rated value, and the bypass circuit 15 is 20% of the rated water supply flow rate.
In the above case, the output signal S13 of the N/A switch 13
is bypassed without passing through the speed limiter 14, and is output as the speed request signal S15. The speed error limiter 16 receives the speed request signal S14 or S15.
is compared with an actual generator speed signal S27 fed back from a recirculation MG device, which will be described later, and an output signal corresponding to the deviation, that is, a deviation signal S16, is sent out. The speed controller 17 is the speed error limiter 1
Control signal S17 according to deviation signal S16 from 6
is applied to one input terminal of the low value priority circuit 19 in the speed control signal setter 18. Low value priority circuit 19
A speed request signal S14 or S15 outputted from the speed limiter S14 and the bypass circuit 15 is applied to the other input terminal of the speed limiter S14.

The low value priority circuit 19 is a circuit that compares the signal S17 input to each input terminal with S14 or S15, and outputs the signal having the smaller value preferentially. The output signal S19 of this circuit 19 is input to a limiter circuit 20 within the same speed control signal setter 18. This limiter circuit 20 is a circuit that determines an upper limit value or a lower limit value for the signal S19 from the low value priority circuit 19, and limits signals exceeding this value to output signals at a certain level.
The output signal S20 of this limiter circuit 20 is given to the scoop tube operating device 21. Scoop pipe operator 2
1 operates the scoop pipe position of the fluid coupling 23 in the recirculation MG device 22. Recirculation MG device 22
The coupling degree between the constant speed drive motor 24 and the generator 25 is changed by operating the position of the scoop pipe of the fluid coupling 23 by the operating device 21, and the speed, that is, the output frequency of the generator 25 is varied. The rotation speed of the recirculation pump motor 26 is controlled. Note that the output of the generator 25 is the output of the tachometer generator 2.
7, it is converted into an actual generator speed signal S27, and fed back to the speed error limiter 16 described above.

Next, the operation of the apparatus configured as described above will be explained. For the sake of simplicity, it is assumed that the main controller 11 and the M/A switch 13 are in automatic mode, and that the output signal S11 from the main controller 11 is greater than or equal to the set value of the speed limiter 12. .

Therefore, first, the operation when increasing the reactor output will be explained. Signal SO from pressure regulator 7
enters the main controller 11, the main controller 11 outputs a speed request signal S11 which has a constant magnitude L at time t1 as shown by curve A in FIG. 2A. This signal S11 is transmitted to the speed request limiter 12, M/
After passing through the A switch 13, it reaches the input end of the speed limiter 14. If the water supply flow rate is less than 20%, the signal S13 from the M/A switch 13 is input to the speed limiter 14 and output as a speed request signal S14 corresponding to the minimum speed of the recirculation pump. If the water supply flow rate is 20% or more, the signal S13 passes through the bypass circuit 15 and is output as the speed request signal S15. The speed request signals S14 and S15 are the same as the output signal S11 of the main controller 11, except for their target levels. Therefore, in the following explanation, the signal S15 will be explained as the final speed request signal.

The speed request signal S15 is transmitted to the speed error limiter 16.
As a result, the signal from the tachogenerator 27, that is, the actual generator speed signal S27, is compared, and the deviation signal S16 is input to the speed controller 17. Then, the speed controller 17 outputs a speed control signal S17 that gradually increases with a predetermined time constant as shown by curve B in FIG. 2A.
is sent. This signal S17 is the low value priority circuit 1
into one input end of 9. The other input terminal of the low value priority circuit 19 is supplied with the speed request signal S15. Therefore, both signals S15 and S17 are compared, but as is clear from the relationship between curves A and B in FIG. It shows a small value. Therefore, the speed control signal S1 is outputted from the low value priority circuit 19 as shown by curve C in FIG. 2B.
7 is prioritized and output as the output signal S19.
This signal S19 is limited to upper and lower limits by a limiter circuit 20 and is given to the operating device 21 as a final speed control signal S20. In order to simplify the explanation, the following explanation will be made assuming that the signal S19=S20. When the signal S20 is applied to the scoop pipe operating device 21, this operating device 21 changes the scoop pipe position of the fluid coupling 23 according to the magnitude of the speed control signal S20 from the limiter circuit, and controls the drive motor 24 and the generator 25. increase the degree of bonding with As a result, the rotational speed of the generator 25 increases and its frequency increases, so that the speed of the recirculation pump motor 26 increases,
The speed of recirculation pump 10 increases.

On the other hand, as the rotational speed of the generator 25 increases, the output signal S27 of the tachogenerator 27 also gradually increases. However, since the generator 25 is driven via the fluid coupling 23, the response to the speed control signal S20 input to the operating device 21 is delayed. Therefore, at time t2, the speed control signal S20 (=S19) becomes the second
Even if the actual generator speed signal S27 reaches the target value L, as shown by curve C in FIG. Therefore, at this point, the signal S15> from the speed error limiter 16
A deviation signal S16 based on the relationship S27 is output. Therefore, the output signal S17 of the controller 17 continues to increase as shown by the curve B' in FIG. 2A.
However, after time t2, the magnitude relationship of the two signals S17S15 input to the low value priority circuit 19 is reversed.
The speed request signal S15 is smaller than the speed control signal S17. Therefore, after time t2, the speed request signal S15 becomes the output signal S1 of the low value priority circuit 19.
9 as shown in the curve C' of FIG. 2B.
The above signal S19 whose upper limit is suppressed to a certain level L
is input as the speed control signal S20 to the operating device 21 through the limiter circuit 20, the rate of increase in the rotational speed of the generator 25 will rapidly slow down after time t2. Thus, the actual generator speed signal S27 reaches the target value L at time t3 as shown by the D' curve in FIG. 2C.
It reaches the target value L and then slightly overshoots, but quickly stabilizes to the target value L. In other words, the speed of the generator 25 is stabilized at the target value with almost no overshoot. As a result, the core flow rate also reaches the target value with almost no overshoot. Therefore, an excessive increase in reactor output can be avoided and the integrity of the fuel can be maintained. In the conventional device without the low value priority circuit 19, as shown in curve E in FIG.
As a result, the rotational speed of the generator 25 will also greatly overshoot as shown by curve F in FIG. 2C, leading to an excessive increase in reactor output and impairing the integrity of the fuel. Therefore, in the conventional device, the speed request signal S11 is made to have a very gentle rise as shown in the curve G in FIG. 2A, and the controller 17
It is assumed that the output signal S17 shows a more gradual rise like the curve H in FIG. 2A. In this way, the signal is directly transmitted to the operating device 2 as shown in the curve shown in FIG. 2B.
Even with the input signal S20 to 1, care is taken to ensure that the generator speed asymptotically approaches the target value and does not cause a significant overshoot, as shown by the N curve in FIG. As a result, the response speed could not be increased. However, in this device, the overshoot can be suppressed to almost no occurrence due to the function of the low value priority circuit 19, so that the response speed can be sufficiently increased and control operations with good followability can be performed.

Note that when the reactor output is reduced, the operation is the same as that described above, so a description thereof will be omitted.

By the way, if the feedback system that feeds back the actual speed signal S27 of the generator 25 malfunctions or breaks down and feeds back a signal indicating a decrease in speed during speed increase control, the speed error limiter would An extremely large deviation signal is sent from the controller 16, and accordingly, a large speed increase request signal is output from the controller 17, which significantly increases the core flow rate and forces an emergency shutdown of the reactor. However, in this device, even if a malfunction or failure occurs in the feedback system as described above, the input signal to the scoop tube operating device 21 is immediately switched to the speed request signal at a constant level by the low value priority circuit 19. It is possible to avoid an emergency shutdown of the reactor, improve the operating rate, and maintain the integrity of the fuel rods.

Note that even if the output signal S19 of the low value priority circuit 19 itself shows an abnormally large value due to a failure other than the feedback system, in this device, the upper and lower limits of the signal are limited by the limiter circuit 20. Therefore, excessive control is not performed. Therefore, safety can be further improved.

Note that the present invention is not limited to the above-mentioned embodiment. For example, in the embodiment described above, an application example was shown in which the drive motor 24 and the generator 25 were coupled by a fluid coupling, but the present invention is also applicable to a case where the drive motor 24 and the generator 25 are coupled by other couplings. Further, in the above embodiment, the actual generator speed signal fed back to the speed error limiter 16 was obtained using a tachometer generator, but other means such as converting the speed measured by a speedometer into an electrical signal may be used. The above-mentioned signal may be detected using a device configured as described above. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

As explained above, the first aspect of the present invention provides recirculation of a nuclear reactor by adjusting the rotational speed of a generator connected to a motor via a fluid coupling and driving a recirculation pump motor by adjusting the position of the scoop pipe of the fluid coupling. A reactor recirculation flow control device that controls flow rate includes a main controller that outputs a speed request signal of the generator, a speed request signal output from the main controller, and an actual generator speed signal of the generator. a speed error limiter that obtains a deviation signal between the speed error limiter and the speed error limiter; A low value priority circuit that compares the magnitude with a speed request signal and outputs the smaller signal with priority, and an operation that operates the scoop pipe position of the fluid coupling based on the signal output from this low value priority circuit. It is equipped with a container. Therefore, the rotational speed of the generator can be controlled without overshooting or undershooting the target value, and an excessive increase in the output of the reactor can be prevented, so that the integrity of the fuel can be maintained.

Further, the second invention controls the recirculation flow rate of the nuclear reactor by adjusting the rotational speed of a generator connected to the motor via a fluid coupling and driving the recirculation pump motor by adjusting the position of the scoop pipe of the fluid coupling. The reactor recirculation flow control device includes a main controller that outputs a speed request signal for the generator, and a deviation signal between the speed request signal output from the main controller and the actual generator speed of the generator. a speed error limiter that generates a speed error limiter, a speed controller that forms a speed control signal according to a deviation signal output from this speed error limiter, and a control signal formed by this speed controller and the speed request signal. A low value priority circuit that compares the magnitude and outputs the smaller signal with priority, a limiter circuit that limits the upper and lower limits of the signal output from this low value priority circuit to below a certain level, and this limiter. and an operating device that operates the position of the scoop pipe of the fluid coupling based on the output signal of the circuit. Therefore, as in the first invention, the rotational speed of the generator can be controlled without overshooting or undershooting the target value, and even if a signal indicating an abnormal value is output from the low value priority circuit due to a failure or the like. The upper and lower limits of the signal can be limited to below a certain level by a limiter circuit, making it possible to further improve the safety of the nuclear reactor.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the embodiment. 1... Reactor pressure vessel, 2... Main steam pipe, 3... Turbine, 4... Main generator, 5... Condenser, 6... Water supply pump, 7... Pressure regulator, 8... Recirculation flow rate control device,
9... Recirculation system, 10... Recirculation pump, 11... Main controller, 16... Speed error limiter, 17... Speed controller, 18... Speed control signal setter, 19... Low value priority circuit, 20... Limiter circuit , 21...operator, 2
2... Recirculation MG device, 23... Fluid coupling, 24... Drive motor, 25... Recirculation pump motor drive generator, 26... Recirculation pump motor.

Claims (1)

[Claims] 1. An atom that controls the recirculation flow rate of the nuclear reactor by adjusting the rotational speed of a generator that is connected to a motor via a fluid coupling and drives a recirculation pump motor by adjusting the position of the scoop pipe of the fluid coupling. The furnace recirculation flow rate control device includes a main controller that outputs a speed request signal of the generator, and a deviation signal between the speed request signal output from the main controller and the actual generator speed signal of the generator. a speed error limiter that generates a speed error limiter, a speed controller that forms a speed control signal according to a deviation signal output from this speed error limiter, and a control signal formed by this speed controller and the speed request signal. It is equipped with a low value priority circuit that compares the sizes and outputs the smaller signal with priority, and an operating device that operates the scoop pipe position of the fluid coupling based on the signal output from the low value priority circuit. A nuclear reactor recirculation flow rate control device characterized by: 2. A reactor recirculation flow rate control device that controls the recirculation flow rate of the reactor by adjusting the rotational speed of a generator that is connected to a motor via a fluid coupling and drives a recirculation pump motor by adjusting the scoop pipe position of the fluid coupling. a main controller that outputs a speed request signal of the generator; and a speed error limiter that obtains a deviation signal between the speed request signal output from the main controller and an actual generator speed signal of the generator. , a speed controller that forms a speed control signal according to the deviation signal output from this speed error limiter, and compares the magnitude of the control signal formed by this speed controller with the speed request signal and determines that the magnitude is smaller. a low-value priority circuit that outputs the signal with priority to the lower value; a limiter circuit that limits the upper and lower limits of the signal output from the low-value priority circuit to below a certain level; A nuclear reactor recirculation flow rate control device comprising: an operating device for controlling the position of the scoop pipe of the fluid coupling.