JP3268017B2 - Static variable voltage variable frequency power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static type variable voltage variable frequency power supply using, for example, a thyristor inverter for driving a coolant recirculation pump of a boiling water reactor. The present invention relates to a static variable voltage variable frequency power supply that can prevent a load change or the like expected when a sudden change occurs.

[0002]

2. Description of the Related Art A conventional thyristor inverter-based static type variable voltage variable frequency power supply will be described with reference to a case where the present invention is applied to a boiling water reactor. As one means for controlling the output of a boiling water reactor, a method of controlling a recirculation flow rate of a coolant in a nuclear reactor is employed.

Specifically, power is supplied from a variable voltage variable frequency power supply to a motor for driving a coolant recirculation pump, and recirculation flow control by the recirculation pump is performed by controlling the output of the variable voltage variable frequency power supply. This is done by varying the frequency to vary the rotation speed of the motor.

As the variable voltage / variable frequency power supply, an MG set (motor generator set) having a fluid coupling with variable slip may be used. However, recently, a static type variable voltage variable frequency power supply which is excellent in terms of efficiency, responsiveness and the like has been used frequently.

[0005] This static variable voltage variable frequency power supply device is a DC-AC converter, ie, an inverter mainly composed of a conversion element formed by bridge-connecting thyristors, and controls the ignition phase of each thyristor from a control means. It is configured such that an AC output of a desired frequency can be obtained by controlling with a pulse signal to be output.

[0006]

When the drive power supply of the recirculation pump is a conventional MG set, the output frequency does not exceed the synchronous rotation speed of the drive motor due to its structure. The upper limit of the frequency of the power output from the power supply does not increase significantly. However, in the case of the static variable voltage variable frequency power supply, when a failure occurs in the control system of the thyristor inverter or the like, the output frequency may suddenly increase or fluctuate.

[0007] If the output frequency increases more than the specified value during operation, there is a possibility that the reactor and related equipment will be greatly adversely affected. That is, the rapid increase in the rotation speed of the recirculation pump causes a rapid increase in the recirculation flow rate of the coolant in the reactor, leading to an increase in the reactor power and an increase in the neutron flux and the reactor pressure.

The amount of the neutron flux and the reactor pressure are constantly monitored during the operation of the nuclear power plant, and if these numerical values greatly exceed preset values or change rapidly, the nuclear power plant may become abnormal. A protection system has been established to judge occurrence and to perform a scram, which is an emergency shutdown of the reactor.

Therefore, as a general countermeasure, a method of detecting a sudden increase in the output frequency and stopping the static variable voltage variable frequency power supply can be considered. However, if the power supply of the recirculation pump is stopped immediately, the soundness of the reactor can be secured, but the power of the reactor will drop significantly,
This will significantly reduce the availability of the nuclear plant.

Therefore, a large increase and a rapid change in the output frequency of the static variable voltage variable frequency power supply for driving the recirculation pump is not preferable from the viewpoint of stable operation of the reactor. Appropriate countermeasures to prevent a sudden increase were issues.

An object of the present invention is to make the control means of the static type variable voltage variable frequency power supply redundant, and when a control system or the like breaks down, automatically switch to the sound side control means, thereby causing a problem in the load. It is an object of the present invention to provide a static variable voltage / variable frequency power supply device which prevents the occurrence of the above problem and does not lower the operation rate of an applied plant.

[0012]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
In addition, claim 1 of the present invention provides a rectifier circuit from an in-house AC bus.
Input terminal connected to the motor and output terminal connected to the motor
A static variable voltage variable frequency power supply comprising an inverter having become Te thyristor, said inverter
The speed command signal is
To perform firing phase control of the thyristor
Control means and second control means; a frequency detector for detecting a frequency output from the inverter ;
; And a frequency change rate detector for detecting the rate of change, the
The output of the frequency detection means has exceeded a predetermined set value
And the output of the frequency change rate detecting means is predetermined.
Leaving the output frequency abnormality signal when exceeding the order was set value
Operating the frequency abnormality detecting device to be operated and the first control means.
And the second control means is in a standby state, and
When the output frequency abnormality signal is input, the first
A stop signal is output to the control means, and
An operation command of the barter and a selection command of the second control means
Is input to the second control means when the
Control system operation finger that switches the control means by outputting
Characterized by comprising a decree device.

[0013]

In the static variable voltage variable frequency power supply device, the first driving side for driving the thyristor constituting the inverter is provided .
When a failure occurs in the control means or the like, and the output frequency is rapidly increased or fluctuated, the frequency abnormality detection device that detects the output frequency of the inverter has a frequency or frequency change rate exceeding a set value. to the control system operation command device <br/> for frequency anomaly signal switching example of the second control means when.

[0014] from the control system operation in the signal of the first control means of the frequency abnormality signal and the operation side, with the switching means of said control means issues a stop signal to the driver-side control unit temporarily stops the inverter, the A control system operation permission signal is output to the standby-side second control means when the control system in-operation signal of the first control means on the driving side disappears.

As a result, the first operation side on which the abnormality has occurred can be performed .
Switches to the second control means of the control means automatically standby side, since subsequent the inverter is controlled by the second control means of healthy stand-by side, static variable voltage variable frequency power supplies predetermined Outputs frequency power stably.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings, taking a recirculation pump drive of a boiling water reactor as an example. As shown in the circuit configuration diagram of FIG. 1, the power stepped down from the internal AC bus 1 via the circuit breaker 2 and the input transformer 3 is supplied to the AC input terminal of the rectifier circuit 4 of the static type variable voltage variable frequency power supply. Supplied to Further, a DC output terminal of the rectifier circuit 4 is connected to a DC input terminal of the inverter body 6 via a DC reactor 5.

The inverter body 6 is formed, for example, by connecting a thyristor in a three-phase bridge connection, and has an AC output terminal via a power transformer 7 for driving a recirculation pump of a boiling water reactor (not shown). Is connected to the input end of the electric motor 8. Further, the inverter body 6 is provided with two sets of control devices 9a and 9b having the same specifications, which are control means for conducting the thyristors by controlling the firing phase, and the two sets of control devices 9a and 9b are , Used as a driving side or a standby side.

Further, each of the control devices 9a and 9b includes a speed command converter 10a, 10b, a V / F converter 11a, 11b, a ring counter 12a, 12b, a gate block circuit 13a,
13b and a pulse amplifier 14a, 14b, a speed command signal 15 given from a higher-order speed command system (not shown) is introduced into respective speed command converters 10a, 10b and converted into frequency signals. To V / F converter 11
In a and 11b, the pulse train is converted into a pulse train having a frequency six times the output frequency of the inverter body 6.

The outputs from the V / F converters 11a and 11b are distributed by the ring counters 12a and 12b to pulse signals for firing each thyristor of the inverter body 6, and these distributed pulse signals are separately transmitted to the inverter body 6 Are input to the pulse amplifiers 14a and 14b that generate gate signals for the respective thyristors of the inverter body 6 through gate block circuits 13a and 13b that perform a block operation when the stop command signals 16a and 16b are input. I have.

A voltage transformer 17 is connected to the output side of the output transformer 7, and this output side passes through a frequency abnormality detecting device 18 which is a frequency abnormality detecting means of the present static type variable voltage variable frequency power supply device. And is connected to a control system operation command device 23 which is a switching means of the control means.

The frequency abnormality detector 18 comprises a frequency detector 19, a frequency change rate detector 20 and a comparator 21. The frequency detector 19 and the frequency change rate detector 20 are respectively provided with a voltage transformer 17 , And detects the frequency output from the inverter body 6 and the frequency change rate,
These are introduced into the comparator 21. The comparator 21 controls the output frequency abnormality signal 22 when the output of the frequency detector 19 exceeds a predetermined value, and when the output of the frequency change rate detector 20 exceeds a predetermined value. Operation command device 23
To send to.

The control system operation command device 23 comprises four AND circuits 24a, 24b, 25 as shown in the logic diagram of FIG.
a, 25b and two OR circuits 26a, 26b, etc., and in addition to the output frequency abnormality signal 22,
a, 9b, and a control device selection operation instruction signal 29 from a control system (not shown).
a, 29b and the operation command signal 30 of the inverter body 6 are introduced, and the controller 9a, 9b outputs stop command signals 16a, 16b of the inverter body 6 and control system operation permission signals 28a, 28b.

Further, the control devices 9a and 9b perform conduction control of each thyristor of the inverter main body 6 when the control system operation permission signals 28a and 28b are input from the control system operation command device 23. When the control devices 9a and 9b are operating with respect to the operation command device 23, the control system operation signals 27a and 27b are output, respectively.

Next, the operation of the above configuration will be described. First, among the control devices 9a and 9b, which are two sets of control means in the static variable voltage variable frequency power supply,
It is assumed that the inverter 9 is controlled by the controller 9a, with the controller 9a being on the operating side and one controller 9b being on the standby side.

An inverter operation command signal 30 from a control system (not shown) and a control device selection operation command signal 29a for selecting the control device 9a on the operation side are introduced into a control system operation command device 23 which is a switching means of the control means. If the speed command signal 15 from the upper speed command system is appropriate and the control device 9a is not abnormal, the control system operation command device 23 receives the inverter operation command signal 30 and the control device selection operation command signal 29a. Since there is no input of the output frequency abnormality signal 22 from the frequency abnormality detection device 18, the control system operation permission signal
28a is output to the control device 9a.

As a result, the control device 9a becomes the driving side,
The inverter body 6 is controlled by the pulse signal output from the pulse amplifier 14a, and the operation is performed at the output frequency set by the speed command signal 15. Further, the control device 9a outputs a control system in-operation signal 27a to the control system operation command device 23.

Accordingly, the electric motor 8 drives a recirculation pump, which is a load (not shown), at an appropriate speed, and a predetermined recirculation flow rate and a reactor output are obtained in the nuclear reactor, so that a stable operation of the nuclear power plant is performed. On the other hand, in the control device 9b, the speed command signal 15 is input, but the control system operation command device 23 does not output the control system operation permission signal 28b.
Therefore, a standby state is set.

Next, if the speed command signal 15 is abnormal,
If the output frequency of the inverter body 6 abnormally rises or suddenly changes due to a failure of the circuit speed command converter 10a or the V / F converter 11a in the control device 9a, this change immediately occurs. It is detected by the frequency abnormality detection device 18 via the transformer 17. That is, the output signals of the frequency detector 19 and the frequency change rate detector 20 are compared with respective predetermined set values in the comparator 21. When one of the output signals exceeds the set value, the frequency abnormal signal 22 is output. Is output to the control system operation command device 23.

The control system operation command device 23 outputs a stop command signal 16a to the gate block circuit 13a of the control device 9a on the operation side when the frequency abnormality signal 22 is input. As a result, the gate block circuit 13a performs a block operation and stops supplying the pulse signal to the pulse amplifier 14a. Therefore, the operation of the inverter body 6 is temporarily stopped, the power supply to the electric motor 8, which is the drive source of the recirculation pump, is cut off, and the electric motor 8 and the recirculation pump naturally fall due to their own inertia.

On the other hand, in the control device 9b on the standby side,
When the operation side control device 9a stops, the control system in-operation signal 27
The output of a disappears, and the control system operation command device 23 outputs a control system operation permission signal 28b to the control device 9b on the standby side. Therefore, the inverter body 6 is again controlled by the sound control device 9.
The operation is controlled by a pulse signal from the pulse amplifier 14b from b, and the operation is performed at the set appropriate output frequency.

As a result, the motor 8 that has once been naturally decelerated is operated again without stopping, and is controlled by the rotation speed according to the speed command signal 15. The recirculation flow rate of the recirculation pump driven by this quickly returned to an appropriate value, and the reactor output was stable, so that the reactor pressure did not increase,
Safe operation of the reactor is ensured, and the operation rate of the nuclear plant is not reduced.

When the control devices 9a and 9b are switched in accordance with the operation of the frequency abnormality detecting device 18, the cause of the abnormality of the control system including the control device 9a is investigated separately and the restoration maintenance is performed. The device 9a is set on the standby side. The initial operation side selection of the control devices 9a and 9b can be arbitrarily performed by the control device selection operation instruction signals 29a and 29b.
The same operation is performed when a is set as the standby side.

In the control system operation command device 23, as shown in FIG. 2, the frequency abnormality signal 22 from the frequency abnormality detection device 18 and the control system operation signal 27a from the control device 9a are
When introduced into the AND circuit 24a, it sends a stop command signal 16a to the control device 9a. Similarly, the AND circuit 24b sends a stop command signal 16b to the control device 9b based on the frequency abnormality signal 22 and the control system operating signal 27b of the control device 9b.

The control system in-operation signal 27b transmitted when the control device 9b is on the operation side and used for controlling the inverter main body 6 is branched and passed through a NOT circuit and a time delay circuit to the control device 9a. To the control device selection operation instruction signal 29a to the OR circuit 26b. An output signal of the OR circuit 26b is an AND circuit with the operation command signal 30.
25b, a control system operation permission signal to the control device 9a
28a is output.

Similarly, the control system in-operation signal 27a transmitted when the control device 9a is used on the operation side to control the inverter body 6 is branched, and is split via the NOT circuit and the time delay circuit. 9b is connected to the control device selection operation instruction signal 29b and the OR circuit 26a. As a result, the output signal from the OR circuit 26a is
At the same time, the operation permission signal 28b for the control device 9b is sent out to the AND circuit 25a.

For this purpose, for example, when an operation command signal 30 for the inverter body 6 is output and a control device selection operation instruction signal 29a to the control device 9a given from a control system (not shown) is output, An operation permission signal 28a is output from the AND circuit 25b to the control device 9a. As a result, the control device 9a controls the conduction of each thyristor of the inverter body 6 to start the operation, and outputs the control system operation signal 27a to the AND circuit 24a of the control system operation command device 23.

Here, an abnormal output frequency from the inverter body 6 occurs due to a circuit failure or the like in the control device 9a.
Output frequency abnormality signal 22 from the frequency abnormality detection device 18
Is introduced into the AND circuits 24a and 24b. AND circuit 24a
In, the stop command signal 16a is transmitted to the control device 9a by the frequency abnormal signal 22 and the control system in-operation signal 27a that has been input previously.

The stop command signal 16a is transmitted to the control system operation command device 23.
When introduced, the continuity control of each thyristor of the inverter main body 6 in the control device 9a is stopped by the gate block circuit 13a that performs the block operation, so that the operation of the inverter main body 6 is temporarily stopped, and The motor 8 whose power supply has been cut off and the recirculation pump (not shown) naturally fall.

Next, the inverter body 6 in the control device 9a
Stop of the thyristor conduction control of
The control system in-operation signal 27a for the circuit 24a is stopped.
When the control system in-operation signal 27a stops, NO
From the OR circuit 26a via the T circuit and the time delay circuit, AND
Since the signal is output to the circuit 25a, the AND circuit 25a
The operation permission signal 28 is derived from the previously input operation command signal 30
b to the control device 9b.

As a result, the operation control of the inverter body 6 is started again by the standby control device 9b instead of the control device 9a that has stopped operating due to a failure or the like, and electric power at a normal output frequency is supplied to the motor 8. Then, the motor 8 and the recirculation pump, which have temporarily dropped naturally, return to the normal operation again.

Therefore, it is possible to easily prevent a rise or a sudden change in the core flow rate, the reactor power, the reactor pressure, etc., which may be caused when the control system of the static type variable voltage variable frequency power supply unit fails due to a failure. Can be operated without stopping the coolant recirculation pump immediately, and without reducing the operation rate of the nuclear power plant.

[0042]

As described above, according to the present invention, in a static variable voltage variable frequency power supply, even if one of the control systems fails, the output frequency rises more than a set value and abruptly changes with respect to the load. Since there is no problem, there is an effect that the reliability and safety of the operation of a static type variable voltage variable frequency power supply device and a plant or the like employing the same are improved.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of one embodiment according to the present invention.

FIG. 2 is a logic configuration diagram of a control system operation command device according to one embodiment of the present invention.

[Explanation of symbols]

1 ... in-house AC bus, 2 ... breaker, 3 ... input transformer, 4 ...
Rectifier circuit, 5 DC reactor, 6 inverter body,
7: output transformer, 8: electric motor, 9a, 9b: control device,
10a, 10b: speed command converter, 11a, 11b: V / F converter, 12a, 12b: ring counter, 13a, 13b: gate block circuit, 14a, 14b: pulse amplifier, 15: speed command signal, 16a, 16b … Stop command signal, 17… Voltage transformer,
18 ... frequency abnormality detection device, 19 ... frequency detector, 20 ... frequency change rate detector, 21 ... comparator, 22 ... frequency abnormality signal, 23
... Control system operation command device, 24a, 24b, 25a, 25b ... AN
D circuit, 26a, 26b: OR circuit, 27a, 27b: control system operating signal, 28a, 28b: operation permission signal, 29a, 29b: control device selection operation instruction signal, 30: operation command signal.

Claims (1)

(57) [Claims] 1. An input from an in-house AC bus via a rectifier circuit.
End connected and the output connected to the motor.
A static variable voltage variable frequency power supply comprising an inverter having an Lister, respectively provided connected to the inverter, the speed command
Converting the signal to a frequency signal and controlling the firing phase of the thyristor
A first control unit and a second control unit for performing control, and a frequency detection for detecting a frequency output from the inverter.
And vessels, comprising a frequency change rate detector for detecting the rate of change of the frequency, the output is predetermined et al of the frequency detecting means
If the value exceeds the set value, and a frequency abnormality detection device output of the frequency change rate detection means outputs an output <br/> frequency abnormality signal when it exceeds a predetermined setting value, the first Operating state of the control means and the second control means
The stage is in a standby state, and the output frequency abnormality signal is input.
Output a stop signal to the first control means
In both cases, the operation command of the inverter and the
When the selection command of the second control means is input, the second
By outputting an operation permission signal to the control means,
Static variable voltage variable frequency power supply apparatus characterized by comprising a control system operation command device for performing instead.