JP2585410B2 - Stationary variable voltage frequency power supply for reactor circulation pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a stationary variable voltage frequency power supply for driving and controlling a circulation pump for controlling a core flow rate for adjusting the output of a boiling water reactor. In particular, the present invention relates to restart control at the time of an instantaneous power failure.

(Prior Art) Conventionally, a device for driving and controlling a circulating pump of a boiling water reactor uses an MG set 1 as shown in the configuration diagram of FIG. 3, which is composed of an electric motor 2, a fluid coupling 3, and a generator. The generator 4 controls the driving motor 6 of the recirculation pump 5 to be variable in speed. The motor 2 of the MG set 1 is supplied with a constant voltage frequency power from the AC power supply 7 and rotates at a constant speed. By operating the position of a rake pipe (not shown) in the fluid coupling 3 from the outside, the The power given to the drive motor 6 is changed by changing the speed. The recirculation pump 5 using the MG set 1
The rotation speed of the recirculation pump 5 is substantially proportional to the frequency applied to the driving motor 6 directly connected thereto, that is, the output frequency of the generator 4 of the MG set 1, and the rotation speed of the recirculation pump 5 is determined in consideration of the safety of the reactor. It is usually limited to 20% to 100% of the rating. Here, the reason for setting the lower limit to 20% is that, when the recirculation pump 5 is operated at a low speed of 20% or less of the rated value, cavitation occurs near the recirculation pump 5 and the jet pump in the reactor. This is because it is not preferable from the viewpoint of safety of the reactor operation, for example, the output is fluctuated due to crushing the void which is a factor of the output adjustment.

The MG set 1, the driving motor 6, and the recirculation pump 5
In this combination, the inertia possessed by each is large, and therefore, even if an instantaneous power failure (hereinafter abbreviated to instantaneous power failure) occurs in the AC power supply 7 during operation, the power loss is restored for several hundred milliseconds. There is no problem that the rotation speed of the circulation pump 5 decreases. However, if the power outage is prolonged, there is a problem that the output decreases due to a decrease in the core flow rate due to a decrease in the rotation speed. Therefore, the restart speed of the recirculation pump 5 and the MG set 1 It is required that careful operation by a skilled operator is required for the output adjustment and the like.

(Problems to be Solved by the Invention) Recently, instead of the MG set, a static variable voltage frequency power supply device (hereinafter simply referred to as an inverter) using a semiconductor inverter is being adopted because of its superiority in control and maintenance. . However, since this inverter is an electronic device and has almost no inertia, the rotation of the recirculation pump rapidly decreases when the power supply stops momentarily. This phenomenon is prominent when an internal pump having a large capacity is employed. In addition, in this case, if the momentary power failure is prolonged, or if the reactor is operating at low output and the circulation pump is operating at low speed, the rotation speed of the circulation pump may drop to 20% or less of the rated value when power is restored. In many cases, there is a problem that restart of the circulation pump by the conventional operation is easily performed at a rotation speed that causes cavitation.

The present invention has been made in view of the above, and it is an object of the present invention to immediately recover a power supply after an instantaneous power failure from a power loss signal detected by an inverter which is a driving power supply of the circulation pump and a rotation speed signal of the circulation pump. An object of the present invention is to provide a static variable voltage frequency power supply for a reactor circulation pump that accelerates the rotation speed of a circulation pump to a speed at which cavitation does not occur and restarts the reactor to perform stable reactor operation.

[Means for Solving the Problems] Upon an instantaneous interruption of the power supply of the coolant circulation pump in the nuclear reactor and subsequent restoration, a power failure detection unit that detects a power loss and issues a power loss signal, A speed detecting unit that detects a pump rotation speed and issues a pump rotation speed signal, a speed setting unit that emits a signal equal to or greater than a predetermined set value and a signal equal to or less than a set value from the pump rotation speed signal, and other control system switching in the inverter A completion signal and a restart signal of the circulating pump are inputted, and a momentary stop of the circulating pump power supply and its recovery from the power loss signal and the inverter control system switching completion signal and the failure confirmation and switching of the control system in the inverter are performed. From the power loss signal and the signal higher than the set value of the circulation pump rotation speed, restart control of the circulation pump at the time of a momentary power failure recovery and takeover to the upper control system operation, and the rotation speed of the circulation pump The rotation speed of the circulating pump in the state of less than the set value from the set value or less signal and the circulating pump restart completion signal to the set value or more, and then instantaneously stop the restart control and take over to the higher-level control system operation A restart control device is provided.

(Operation) When the power supply of the coolant circulating pump in the nuclear reactor is momentarily shut down and the power is restored, this is detected, and a power loss signal and a control system switching completion signal in the inverter are input. Then, the control system failure in the inverter is confirmed.
Also, confirm that there is no cavitation based on the power loss signal and the signal higher than the set value of the circulation pump rotation speed, that is, the rotation speed of the circulation pump, and restart the circulation pump and take over to the higher-level control system operation. carry out. In addition, a signal indicating that the rotation speed of the circulation pump is equal to or less than the set value, that is, the possibility that cavitation may occur in the circulation pump, and a signal indicating that the circulation pump has been restarted is input, and the rotation speed of the circulation pump is temporarily equal to or greater than the set value The reactor is accelerated to avoid the occurrence of cavitation, and then performs restart control and handover to a higher-level control system, thereby performing stable operation of the reactor by core flow rate control.

Example An example of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an inverter, and FIG. 2 is a logic configuration diagram of a momentary power failure restart control device. The inverter 10 includes a semiconductor inverter for variable voltage and variable frequency and its control means and a speed detection unit 11, a speed setting unit 12, a power failure detection unit 13, and a momentary power failure restart control device 20. Are duplicated to increase reliability. An AC power source 7, a driving motor 6, a recirculation pump 5, and a higher-level control system 14 are provided outside. When the power failure detecting unit 13 detects a power failure, a power loss signal S1 is input to the instantaneous power failure restart control device 20. The instantaneous power failure restart control device 20 has a logic configuration shown in FIG. 2, and switches the control system in the inverter to the standby side where the control system in the inverter is duplicated, using the power loss signal S1 as the inverter control system switching signal S4. A first wipeout 23 for inputting the power loss signal S1 via the NOT circuit 21 and activating the inverter control system switching completion signal S2 resulting from the inverter control system switching signal S4 via the first delay circuit 22. , A second wipe-out 25 operated by this output, and a second wipe-out 25
The first circuit outputs the momentary power failure restart logic circuit operation signal S3 with the feedback circuit via the power supply and the power loss signal S1 as inputs.
An OR circuit 26, an output of a third wipe-out 28 connected to the output side of the NOT circuit 21 operated by the output signal S3 and the output signal S3 via a delay circuit 27, and a speed detection of the inverter 10. A second AND circuit 29 that receives a pump rotation speed signal S5 from the unit 11 and a signal S6 of 20% or more from the speed setting unit 12 and outputs a first pump restart signal S8; Circuit operation signal S3 and third wipe-out
A third AND circuit 30 which receives the output of the speed setting unit 12 and the signal S7 of 20% or less from the speed setting unit 12;
A fourth AND circuit 32 which receives the pump restart signal S9 and the pump restart completion signal S10 through the third delay circuit 31
And the output of the 20% acceleration signal S11 and the speed setting unit 1
Fifth AND circuit 33 for inputting signal S6 of 20% or more from 2
A sixth AND circuit 34 which receives the first pump restart signal S8 and the pump restart completion signal S10 as inputs; It is composed of a second OR circuit 35 that outputs a control switching signal S12.

Next, the operation of the above configuration will be described. When a momentary power failure occurs in the AC power supply 7, a power failure detection unit in the inverter 10
13 detects this and outputs a power loss signal S1 to the instantaneous power failure restart control device 20. Upon input of the power loss signal S1, the instantaneous power failure restart control device 20 first exchanges the signal for holding the instantaneous power failure restart logic circuit operation signal S3 with the inverter control system switching signal S4. The inverter control system switching signal S4 determines whether the instantaneous power failure is caused by a failure in the control system in the inverter 10, and determines whether the instantaneous power failure restart control is not performed easily. Switch the control system to the standby side. If the power loss signal S1 disappears due to this switching operation, the NOT circuit 21
Output circuit and inverter control system switching completion signal S2 delay circuit 22
By stopping the instantaneous power failure restart logic circuit operation signal S3 with an AND signal with the signal that the inverter control system switching completion signal S2 disappears after the predetermined time period, the failure confirmation of the control system of the inverter 10 and the switching operation are performed. However, the instantaneous power failure restart control due to the control system malfunction is prevented from malfunctioning.

If the power loss signal S1 continues even after the switching, the instantaneous power failure restart control device 20 continues the instantaneous power failure restart control. The speed detector 11 outputs the rotation speed signal S5 of the recirculation pump 5 and the signal S6 or 20%
Hereinafter, the signal S7 is output from the instantaneous power failure restart control device 20. For example, the speed detector 12 detects the speed from the electromotive force of the recirculation pump 5 due to the residual magnetism, and after the power is restored, the inverter 10 detects the speed.
Speed is detected from the output frequency. Here, first, when the rotation speed of the recirculation pump 5 is 20% or more, since the pump rotation speed signal S5 is 20% or more signal S6, the NOT signal of the power loss signal S1, which is the power recovery signal, and the instantaneous power failure restart logic. In response to the AND signal of the circuit operation signal S3, the second AND circuit 29 generates a first pump restart signal S8. This is because the restart signal of the recirculation pump 5 is issued and the recirculation pump 5 is connected to the inverter 10 even though the power supply has not been restored after the momentary power failure due to a failure of the control system in the inverter 10. This is to prevent a sudden decrease in rotation speed. The NOT signal of the power loss signal S1 is a momentary power failure restart logic circuit operation signal S3.
When the predetermined time period elapses by the second delay circuit 27 after the is output, the power loss is determined to be not a momentary power failure but a normal power failure, and the restart of the recirculation pump 5 is prevented. When the restart is completed, the normal operation of the recirculation pump 5 is confirmed after the power is restored by the AND signal of the first pump restart signal S8 and the pump restart completion signal S10. The higher-order control system control switching signal S12 taken over by the higher-order control system 14 that performs the normal output control is output from the second OR circuit 35, and the restart control by the instantaneous power failure restart control device 20 and the inverter 10 ends.

Next, when the rotation speed of the recirculation pump 5 is at a low speed of 20% or less of the rated value at which cavitation occurs at the time of restart after the power is restored, the speed detection unit 11 and the speed setting unit 12 are used.
From the instantaneous power failure restart control device 20 to the pump rotation speed signals S5 and S20.
% Signal S7 is output. Also at this time, the recirculation pump 5 is restarted by an AND signal of the NOT signal (power recovery signal) of the power loss signal S1 and the instantaneous power failure restart logic circuit operation signal S3, and the transient phenomenon at the time of the restart is stopped. Third delay circuit 31
After the operation, the 20% acceleration signal S11 is output from the fourth AND circuit 32, and the rotation speed of the recirculation pump 5 is quickly accelerated to 20% by the inverter 10. This results in more than 20% signal
The upper control system that confirms that the recirculation pump 5 has reached the normal operation region where cavitation does not occur based on the output signal from the fourth AND circuit 32 with S6, and transfers the subsequent control to the upper control system 14. The control switching signal S12 is supplied to the second OR circuit 35.
The restart control by the instantaneous power failure restart control device 20 and the inverter 10 is terminated.

In the above embodiment, the recirculation pump 5 in which the core coolant circulation pump is installed outside the reactor pressure vessel and the instantaneous power failure restart control device 20 are configured with a plurality of logic circuit configurations, and the cavitation avoidance set value is set at the rated rotation speed. Although described as 20% or more, this recirculation pump 5 is installed in the reactor pressure vessel to be an internal pump in which the pump and the motor are integrated, and the instantaneous power failure restart control device 20 is used as software in a computer. Further, even if the speed setting value is selected to a value other than 20% as required, the same operation and effect as those of the above-described embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, even if an instantaneous power failure occurs in the power supply of the circulating pump that controls the core flow rate, which is a part of the output control function, during the operation of the boiling water reactor, Automatically restarts quickly without the need for skilled operators, avoids stoppage of the circulation pump due to this momentary power failure, and causes harm to the recirculation pump and its flow path when restarting after power is restored. This has the effect of safely operating the reactor without causing any serious phenomena and improving the availability and reliability of the nuclear power plant.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a static variable voltage frequency power supply device of the present invention, FIG. 2 is a logic configuration diagram of an instantaneous interruption restart control device, and FIG. 3 is a configuration diagram of a conventional MG set. 5 ... recirculation pump, 6 ... drive motor, 7 ... AC power supply, 10 ... inverter, 11 ... speed detection unit, 12 ... speed setting unit, 13 ... power failure detection unit, 14 ... Control system, 20: Instantaneous power failure restart control device, 21: NOT circuit, 22, 27, 31: Delay circuit, 23, 25, 28 ... Wipeout, 24, 29, 30, 32, 33, 34 …… AND circuit, 26, 35 …… OR circuit. S1 ... Power loss signal, S2 ... Inverter control system switching completion signal, S3 ... Momentary power failure restart logic circuit operation signal, S4 ... Inverter control system switching signal, S5 ... Pump rotation speed signal, S6 ... 20 % Signal, S7 ... 20% or less signal, S8 ... first pump restart signal, S9 ... first pump restart signal, S10 ... pump restart completion signal, S11 ... 20% acceleration signal , S12 ... High-order control system control switching signal.

Claims (1)

(57) [Claims] 1. A static variable voltage frequency power supply for a core coolant circulation pump of a boiling water reactor, comprising: an instantaneous power failure of a power supply and a power loss signal detected upon restoration of the power supply; a control system switching completion signal; The rotation speed signal is input with a signal of a set value or more and a signal of a set value or less and a restart completion signal of the circulating pump, and an instantaneous power failure and recovery of the power of the circulating pump from the power loss signal and the control system switching completion signal and the static type. Confirmation of a control system failure in the variable voltage frequency power supply unit, and furthermore, from the power loss signal and the signal of the rotation speed signal of the circulation pump or higher, to the restart operation of the circulation pump and the operation of the higher-level control system when the instantaneous power failure is restored. After the rotation speed of the circulating pump is accelerated to the set value or higher from the signal below the set value of the rotation speed signal of the circulation pump and the restart completion signal of the circulation pump, And upper control system reactor circulating pump still variable voltage frequency power supply, characterized in that provided with the auto-restart control unit that performs handover control of the operation.