JPS63114571A - Static type variable frequency power supply - Google Patents

Abstract

PURPOSE:To improve the reliability, by performing the gate block of a static type variable frequency power source before opening an input breaker in case a recirculating pump is urgently stopped. CONSTITUTION:A static type variable frequency power source 1 is connected to a bus bar 2 through an input circuit beaker 3 and an input transformer 4, while it is connected to a motor M for a recirculating pump, etc., for nuclear reactor coolant through an output transformer 5. At this moment, a power source stopping logic unit 9 is provided on the output side of a gate pulse control gear 8, where the gate block signal never fails to be outputted, if the pump trip signal is inputted there, and then the breaker trip signal outputted. This logic unit 9 ordinarily stops at the ordinary stopping signal from an operational control gear 14. In the pump trip signal, etc., from a monitor 6 in urgently stopping, after the gate block signal is delayed for a predetermined time in a delay circuit, it is given to a pump trip logic unit 7.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to a reactor coolant recirculation pump (hereinafter referred to as PLRP) or a reactor built-in coolant recirculation pump in a nuclear power plant. The present invention relates to a static variable frequency power supply device used as a power supply for a pump (hereinafter referred to as RIP).

(Prior Art) Generally, an MG set is used to drive PLRP. The M-G set converts the rotational speed of the electric motor to an arbitrary rotational speed using a fluid coupling, thereby changing the rotational speed of the generator to obtain AC variable frequency power and generate PLRP.
It is supplied to the electric motor for driving the motor. However, when a pump trip signal occurs, simply cutting off the human power to the M-G set will not stop the PLRP immediately because power is supplied by the inertia of the M-G set, and it will take approximately several seconds to stop. It takes. Therefore, a dedicated breaker (
A RPTL (hereinafter referred to as a disconnector) is installed to enable immediate shutdown.

However, due to recent remarkable advances in semiconductor technology and AC variable speed control technology for rotating machines that use semiconductors, the M-G set has been replaced with a static variable frequency power source that uses semiconductor elements in order to improve reliability and maintainability. There is a trend toward replacing the conventional power source with a static variable frequency power source to drive the RIP. This stationary variable frequency power supply
They are connected and used as shown in the figure. That is, the fourth
1 in the figure is this stationary variable frequency power supply, which is connected to the bus 2 via an input breaker 3 and an input transformer 4, and is connected to a PLRP or RIP via an output transformer 5.
It is connected to an electric motor M for use.

In addition, the internal structure of a static variable frequency power supply is such that AC power supplied from the input transformer 4 is first converted to DC, two semiconductor devices are connected in series, and three semiconductor devices are connected in parallel. Ru. Name the semiconductor elements as U-phase, ■phase, W-phase, X-phase, Y-phase ratio, and Z-phase. And U
One phase is output to the output transformer 5 from between the ambiguous conductors in which the phase semiconductor and the One phase is output to the transformer 5, and one phase is output to the output transformer 5 from between the bidirectional conductors in which the W-phase semiconductor and the Z-phase semiconductor are connected in series, so that a three-phase AC output is obtained. .

With this connection, the stationary variable frequency power supply 1 converts AC power input from the bus 2 into power at a required frequency for driving the electric motor M. There is no inertial force in this stationary variable frequency power supply 1, so when a pump trip signal occurs, simply cutting off the input power causes the PLRP or RIP to turn off.
Since the breaker stops immediately, there is no need to provide an RPTL or a disconnector like in the MG set, which is advantageous in terms of reducing the number of circuit breakers and simplifying cable construction.

In the case of normal stop, after the normal stop signal generated from the operation control device 14 is given to the gate pulse control device 8, a control signal (hereinafter referred to as gate block) that stops the operation of the stationary variable frequency power supply 1 (hereinafter referred to as gate block) is given to the gate pulse control device 8. Hereinafter referred to as a gate block signal), the stationary variable frequency power supply 1
The gate block is completed. After this, when opening the input breaker 3 to remove the AC voltage applied to the static variable frequency power supply 1, the manual breaker operating device 11 should output a manual breaker disconnection signal and give it to the input breaker 3. This is done by

(Problem to be Solved by the Invention) When an emergency stop such as a pump trip is required, the pump trip signal generated from the reactor condition monitoring device 6 at the time of an accident is sent to the pump trip logic device 7 and the gate pulse control device 8. At the same time, a breaker trip signal and a stop signal (gate block signal) are generated from the respective devices, and the operation of the input breaker 3 and the static variable frequency power supply 1 is stopped.

However, depending on the timing at which the pump trip signal is generated, the following problem may occur, which will be explained using FIG. 3(b). Assuming that the gate block timing of the gate pulse control device 8 is set to generate the gate block signal after detecting the U-phase pulse and then detecting the X-phase pulse, immediately after the U-phase pulse is generated. If a pump trip signal is given to
2 delays will occur. This delay is greater than the delay T1 from 10 between the application of the pump trip signal to the pump trip logic 7 and the output of the breaker trip signal, which is determined by the characteristics of the pump trip cooking device 7.

For this reason, the human-powered circuit breaker 3 is opened before the completion of the gate block, but if this is done at the time t1 when the human-powered AC voltage is at its maximum, a strong surge voltage will be generated in the static variable frequency power supply 1 or the gate pulse control device 8. This may lead to accidents such as damage to semiconductor devices.

Therefore, in order to solve such problems, it is an object of the present invention to provide a stationary variable frequency power supply device that is equipped with a simple logic device to prevent the above-mentioned accident from occurring when stopping a PLRP or RIP in an emergency. do.

[Structure of the invention]

(Means for Solving the Problems) A static variable frequency power supply device of the present invention opens an input breaker after a predetermined time elapses after a control signal for stopping the operation of the static variable frequency power supply device is applied. It is characterized by having a logic device that outputs a signal.

(Function) When a pump trip signal is generated from the reactor condition monitoring device to make an emergency stop of the PLRP or RIP, this signal is given to the gate pulse control device and is sent as two types of signals: a pump trip signal and a gate block signal. After being output, it is applied to the power down logic. The power down logic provides a gate block signal to the static variable frequency power supply and then, after a predetermined time delay, provides a pump trip signal to the pump trip logic.

The static variable frequency power supply gates the input breaker in response to the gate block signal and the pump trip logic provides the breaker trip signal to the input breaker to open the input breaker in response to the pump trip signal.

(Example of the invention) The present invention will be explained with reference to FIG. 1 showing one embodiment.

Unlike the conventional case (Fig. 4), there is a power supply stop logic device 9 (on the output side of the gate pulse control device 8), and when a pump trip signal is input here, the gate block signal is always output and then the Outputs the breaker trip signal.

The circuit configuration of the power-off logic device 9 is shown in FIG.

In the case of normal stop, after the normal stop signal issued from the operation control device 14 is given to the gate pulse control device 8,
Only the gate block signal is output and applied to the static variable frequency power supply 1 to complete the gate block. At this time, the gate block signal is output after a predetermined time delay in the delay circuit 10, but since no pump trip signal is generated, there is no signal output from the AND circuit 13, and the input breaker 3 does not open. After this, when tripping the input breaker 3 to remove the AC voltage applied to the stationary variable frequency power supply 1, a manual breaker operating device 11 issues a manual breaker disconnection signal and sends it to the OR circuit 12. , a pump trip signal is given to the pump trip logic device 7, and the breaker!・It becomes a lip signal and opens the human power breaker 3.

In the case of an emergency shutdown, the pump trip signal generated from the reactor status monitoring device lt6 passes through the gate pulse control device 8 and is output as two types of signals, a gate block signal and a pump trip signal, and is sent to the logic device 9. It will be done. The gate block signal is directly applied to the stationary variable frequency power supply 1 and used for gate blocking. On the other hand, this gate block signal is delayed for a predetermined time by the delay circuit 10, and then ANDed with the pump trip signal output from the gate pulse control device 8 in the AND circuit 13 and output as a pump trip signal. It is applied to the device 7 and used to open the manual breaker 3.

FIG. 3(a) shows a comparison of the generation timing of the breaker trip signal and the gate block signal in this case.

Unlike the conventional example (FIG. 3(b)), the gate block signal always precedes the breaker trip signal, which is delayed by the predetermined time described above, by the delay time T3 caused by the delay circuit 10. Therefore, before the input breaker 3 opens, the gate block of the static variable frequency power supply 1 is always completed, so that no surge voltage is applied to the semiconductor elements or the like.

〔Effect of the invention〕

As explained above, according to the present invention, PLRP or RI
When making an emergency stop of P, the stationary variable frequency power supply gate is blocked before opening the input breaker, which prevents damage to the semiconductor elements of the power supply circuit and allows the reactor to be safely shut down. It is.

Furthermore, the circuit configuration of the logic device that performs the above operations is simple, and secondly, it is highly reliable, and 11th, it is economically viable because power supply repairs and significant decreases in reactor operating rate due to multiple occurrences can be avoided. It has a big effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a static variable frequency power supply device of the present invention, FIG. 2 is a block diagram showing the configuration of a power-off logic circuit of the present invention, and FIG. Timing chart of pump trip signal, breaker trip signal, gate block signal, Fig. 3(b) shows the input AC voltage, pump trip signal, breaker trip signal, gate pulse signal, gate of the conventional static variable frequency power supply device. Timing chart of block signals. FIG. 4 is a block diagram showing the configuration of a conventional static variable frequency power supply device. 1...Static variable frequency power supply, 2...Bus bar, 3...
- Human power breaker, 4... Human power transformer, 5... Output transformer, 6... Reactor status monitoring device, 7... Pump trip logic device, 8... Gate pulse control device, 9・
...Power shutdown logic device, 10...Delay circuit, 11...
・Manual breaker operating device, 12...OR circuit, 13.
...AND circuit, 14...operation control device, M...electric motor.

Claims (1)

[Claims] A stationary variable frequency power supply device that is used as a power source for a reactor coolant recirculation pump or a reactor built-in coolant recirculation pump in a nuclear power plant and receives power through an input breaker. When stopping the operation of the stationary variable frequency power supply in order to suppress the reactor output at the time of generator load cutoff or turbine trip, output a signal to open the input breaker after a predetermined time elapses after the stop signal is given. What is claimed is: 1. A stationary variable frequency power supply device comprising a logic device that performs the following steps.