JPH0534482A - Variable frequency power source device of nuclear reactor coolant recirculation pump - Google Patents

Abstract

PURPOSE:To accurately detect frequency amount, and to avoid unnecessary pump trip. CONSTITUTION:A PLR pump motor 7 of a variable frequency power source device is driven by the outputs of inverter parts 5A, 5B. The ignition phase of each thyristor of each inverter part 5A, 5B is controlled by a gate signal output from a pulse amplifier 13, and the velocity of the PLR pump 8 is controlled. The output frequency of the inverter parts 5A, 5B is surveyed by a first frequency detector 15A and a second frequency detector 15B. The amount (0. 5%) equal to the change in the pulse width of a velocity requirement signal S is added to a maximum speed (102. 6%) in the driving range of the PLR pump 8 by the first frequency detector 15A, to the value of which a predetermined tolerance is added so as to set a value (103.5%). When the output frequency reaches the set value (103.5%), a frequency amount is instantly detected. The velocity requirement signal S is surveyed by the second frequency detector 15B for a fixed period of time, and when the average value reaches a fixed level (102.9%), a frequency amount is detected. The operation of the inverter parts 5A, 5B is stopped by a stop command signal X output from an OR gate 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable frequency power supply device for a reactor coolant recirculation pump capable of variable frequency operation of a pump motor for driving the reactor coolant recirculation pump,
In particular, the present invention relates to a variable frequency power supply device for a reactor coolant recirculation pump capable of detecting a frequency height with an accurate value without malfunctioning.

[0002]

2. Description of the Related Art Generally, power control devices for controlling the reactor power of a boiling water reactor include a control rod drive device for driving control rods and a reactor coolant recirculation pump for controlling the recirculation flow rate of coolant. (Hereinafter, referred to as PLR pump.) In the boiling water reactor, the reactor power is controlled by controlling the position of the control rod and adjusting the recirculation flow rate.

By the way, in most boiling water nuclear power plants, a method of controlling the recirculation flow rate by controlling the speed of the PLR pump is adopted.
For this reason, conventionally, a recirculation pump MG set has been used as a drive power source capable of variable speed control of a PLR pump motor. However, recently, in consideration of the efficiency improvement and the controllability improvement of the entire power supply device, the reactor coolant recirculation pump variable frequency power supply device (hereinafter referred to as PLR
-It is called VVVF. ) Is often introduced.

FIG. 2 shows a conventional PLR-VVVF of this type.
In the figure, reference numeral 1 is a main power supply bus, and the AC (AC) power supply voltage from the main power supply bus 1 is stepped down by the input transformer 2 and converted to direct current by the rectifiers 3A, 3B. The ripples generated at that time are smoothed by the DC reactors 4A and 4B. Then, the inverter units 5A and 5B convert the AC into an AC having an arbitrary operating frequency, the output transformers 6A and 6B boost the voltage, and then the PLR pump motor 7 supplies the PLR pump 8 with the PLR pump 8.
Is driven.

On the other hand, a speed request signal S given from a speed request command system (not shown) is converted into a frequency signal by the command converter 9, and this frequency signal is V /
The F converter 10 converts the pulse train into a pulse train having a frequency six times the output frequency of the inverter units 5A and 5B, and this pulse train signal is converted into a pulse signal for firing each thyristor of the inverter units 5A and 5B by the ring counter 11. It is supposed to be distributed. The distributed pulse signal is
It is input to the pulse amplifier 13 via the gate block circuit 12, and from the pulse amplifier 13, the inverter unit 5
The gate signals of the A and 5B thyristors are output.

On the other hand, as shown in FIG. 2, the output voltages of the inverter units 5A and 5B are input to the frequency detector 15 via the voltage transformer 14, and the frequency detector 15 receives the input voltage. The frequency is compared with a preset value. When the high frequency is detected, the frequency detector 15 causes the gate block circuit 12 to
Stop command signal X is given to the gate block circuit 12
In response to the input of the stop command signal X, the gate block circuit 12 performs a block operation and stops the supply of the pulse signal to the pulse amplifier 13.

Thus, the operation of the inverter units 5A and 5B is stopped, the power supply to the PLR pump motor 7 is cut off, and the soundness of the nuclear reactor is maintained.

[0008]

Conventional PLR-VVV
In the recirculation flow rate control by F, the core flow rate has a certain limit from the viewpoint of maintaining the integrity of the core fuel, and the upper limit of the PLR pump speed is determined based on the maximum allowable core flow rate. In the current 1100 MWe class boiling water reactor plant, the upper limit value is defined as 103%, and in order to satisfy this upper limit value,
The upper limit value of the power supply output frequency is set on the PLR-VVVF side.

By the way, in the PLR-VVVF, since the AC output of an arbitrary frequency is generated by controlling the firing phase of each thyristor, it has a sufficient ability to exceed the upper limit value.

The frequency detector 15 determines whether or not the output frequency of the PLR-VVVF is within the upper limit value.
The detection method is performed by monitoring the speed request signal S (digital signal).

The set value for frequency high detection in the conventional frequency detector 15 is the maximum operating speed 10 of the PLR pump 8.
Although it is based on whether or not the output frequency from the inverter units 5A and 5B is 102.8% with respect to 2.6%, the speed request signal S has a pulse width fluctuation of about 0.5%. Therefore, an error occurs in peak value detection. For this reason, the peak value of the output frequency may momentarily become 102.8% or more despite the normal operating region of the PLR pump 8. In this case, the frequency detector 15 There is a problem that the high output frequency is detected and the pump trip of the PLR pump 8 is caused.

The present invention has been made in consideration of the above-mentioned circumstances, and it is possible to detect the frequency height with an accurate value without malfunctioning and avoid unnecessary pump trips to prevent a decrease in plant operating rate. It is an object of the present invention to provide a variable frequency power supply device for a reactor coolant recirculation pump capable of achieving the above.

[0013]

SUMMARY OF THE INVENTION In order to solve the above problems, a variable frequency power supply device for a reactor coolant recirculation pump according to the present invention comprises an inverter unit for driving a reactor coolant recirculation pump, Variable frequency power supply for a reactor coolant recirculation pump, which comprises a frequency detection unit for detecting the output frequency of the inverter unit, and stop means for stopping the operation of the inverter unit by inputting a high frequency signal from the frequency detection unit. In the device, the frequency detection unit sets a set value in consideration of the fluctuation amount of the speed request signal and a predetermined margin to the maximum operating speed of the coolant recirculation pump, and compares the set value with the output frequency. The first frequency detector and a predetermined value less than the maximum allowable pump speed are set as an average set value, and this average set value is compared with the average value of the output frequencies within a fixed time. And second frequency detector, the one having an OR gate which receives the frequency high signal from the frequency detector.

[0014]

In the variable frequency power supply device for the reactor coolant recirculation pump according to the present invention, the frequency detecting section is composed of two frequency detectors having different characteristics and an OR gate. Of the two frequency detectors, the first frequency detector for instantaneous detection has a set value that takes into account the maximum speed of the operating range of the coolant recirculation pump, the fluctuation of the speed request signal, and the predetermined margin. On the other hand, the second frequency detector detects the frequency height by comparing the average value of the output frequencies within a fixed time with the average setting value. Therefore, the detection accuracy of the output frequency height is improved, and it becomes possible to avoid an unnecessary pump trip and improve the operating rate of the plant.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a variable frequency power supply device for a reactor coolant recirculation pump according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example of a PLR-VVVF according to the present invention. In the figure, reference numeral 1 is a main power bus.
The alternating-current (AC) power supply voltage from the main power supply bus 1 is stepped down by the input transformer 2 and converted into direct current by the rectifiers 3A and 3B. The ripples generated when converting to DC by the rectifiers 3A and 3B are smoothed by the DC reactors 4 and 4B. Then, the inverter unit 5A,
5B is converted into an alternating current of an arbitrary operating frequency, and the output of the converted operating frequency is boosted by the output transformers 6A and 6B, and then supplied to the PLR pump motor 7, and the PLE pump 8
Is driven.

On the other hand, the speed request signal S given from a speed request command system (not shown) is converted into a frequency signal by the command converter 9, and this frequency signal is V /
The F converter 10 converts the pulse train into a pulse train having a frequency that is six times the output frequency of the inverter units 5A and 5B.
It is adapted to be distributed to a pulse signal for firing each of the A and 5B thyristors. The distributed pulse signal is shown in FIG.
As shown in, the pulse signal is input to the pulse amplifier 13 via the gate block circuit 12, and the gate signal of each thyristor of each inverter unit 5A, 5B is output from the pulse amplifier 13 (in the illustrated example, Inverter section 5
Only the B side is illustrated).

As shown in FIG. 1, the output voltages of the inverter units 5A and 5B are input to a first frequency detector 15A and a second frequency detector 15B, which constitute a frequency detection unit, via a voltage transformer 14, respectively. The frequency detectors 15A and 15B compare the input operating frequency with a preset value. The high frequency signals detected by the frequency detectors 15A and 15B are input to the OR gate 16 as shown in FIG. 1, and the stop command signal X is sent to the gate block circuit 12 from the OR gate 16. To be given.

The gate block circuit 12 performs a block operation in response to the input of the stop command signal X, and stops the supply of pulses to the pulse amplifier 13.
This stops the operation of the inverter units 5A and 5B, and P
The power supply to the LR pump motor 7 is cut off, and the pump trips. This gate block circuit 1
2 and the pulse amplifier 13, the inverter unit 5A,
It constitutes a stopping means for stopping the operation of 5B.

The first frequency detector 15A is adapted to instantaneously detect the frequency height of the peak value using the speed request signal S as a parameter. The set value for detecting the frequency height of the peak value is the PLR pump 8 The maximum speed of the operating range is added with the variation of the pulse width of the speed request signal S, and a predetermined margin is added to this value. Specifically, the maximum speed of the operating range of the PLR pump 8 is 102.6%, and the pulse fluctuation amount of the speed request signal S of about 0.5% is added to make it 103.1%. Taking the margin into consideration, it was set to 103.5%, and this 1
03.5% is set as the set value.

On the other hand, in the second frequency detector 15B, the set value for detecting the high frequency is set to an average set value of 103% or less which is the maximum allowable pump speed, for example, 102.9%. Unlike the first frequency detector 15A, the second frequency detector 15B does not instantaneously detect the frequency height, but detects the average value of the speed request signal S within a fixed time, and this average value is set as the average set value. It is supposed to be compared.

Next, the operation of PLR-VVVF will be described.

The AC power supply voltage from the main power supply bus 1 is stepped down by the input transformer 2 and converted into direct current by the rectifiers 3A and 3B, and the ripple generated at that time is smoothed by the direct current reactors 4A and 4B. To be After that, this direct current is converted into alternating current of an arbitrary operating frequency by the inverter units 5A and 5B, and the output of this operating frequency is boosted by the output transformers 6A and 6B and supplied to the PLR pump motor 7. The speed control of the PLR pump motor 7 is performed by controlling the conduction of the thyristors of the inverter units 5A and 5B.

The speed control of the PLR pump motor 7 is performed by a speed request signal S from a speed request command system (not shown). This speed request signal S is converted into a frequency signal by the command converter 9, and is also converted into a pulse train having a frequency 6 times the output frequency of the inverter units 5A and 5B by the V / F converter 10, and further the ring counter. The signal is distributed by 11 to pulse signals for firing the thyristors of the inverter units 5A and 5B. The distributed pulse signal is
After being amplified by the pulse amplifier 13 via the gate block circuit 12, the pulse amplifier 13 outputs the gate signal of each thyristor of the inverter units 5A and 5B.

On the other hand, as shown in FIG. 1, the output voltages of the inverter units 5A and 5B are given to the respective frequency detectors 15A and 15B for detecting the output frequencies of the inverter units 5A and 5B via the voltage transformer 14, respectively. Be done. Both frequency converters 15A and 15B have different frequency detection characteristics, and when at least one of them detects a frequency height, O
A stop command signal X is applied from the R gate 16 to the gate block circuit 12.

The gate block circuit 12 performs a block operation by the input of the stop command signal X and stops the supply of the pulse signal to the pulse amplifier 13. This allows
The operation of the inverter units 5A and 5B is stopped, and the power supply to the PLR pump motor 7 is cut off.

By the way, both frequency detectors 15A, 15B
Is the inverter unit 5 with the speed request signal S as a parameter.
Since the output frequencies of A and 5B are monitored, the signal has a pulse width variation of about 0.5% at maximum, which causes an error in the instantaneous detection.

Therefore, in the first frequency detector 15A, when the pulse width of the speed request signal S is increased by 0.5% at the maximum, that is, when the maximum speed of the operating range of the PLR pump 8 is 102.6%, the pulse width is increased. Add fluctuations 103.
Even if it becomes 1%, it is in the normal operating region for the PLR pump 8, so the frequency height is not detected, and when the value becomes 103.5% by adding a predetermined margin to this value, the frequency becomes It is designed to detect highs instantly.

In the second frequency detector 15B, the first frequency
Unlike the frequency detector 15A, instantaneous detection is not performed, the speed request signal S is monitored for a certain period of time, and the average value is 102.9.
The frequency height is detected when it reaches%.

Therefore, it is possible to detect the frequency height with high accuracy and avoid unnecessary pump trip.

[0031]

As described above, according to the present invention, since the frequency height is detected by the two frequency detectors having different frequency detection characteristics, the detection accuracy is improved, and unnecessary pump trip due to malfunction is avoided. can do.
Therefore, the soundness of the fuel is required and it is possible to prevent the operating rate of the plant from decreasing.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a variable frequency power supply device for a reactor coolant recirculation pump according to the present invention.

FIG. 2 is a configuration diagram showing a variable frequency power supply device of a conventional reactor coolant recirculation pump.

[Explanation of symbols]

 5A, 5B Inverter section 7 PLR pump motor 8 PLR pump 12 Gate block circuit 13 Pulse amplifier 15A First frequency detector 15B Second frequency detector 16 OR gate S Speed request signal X Stop command signal

Claims (1)

Claim: What is claimed is: 1. An inverter unit for driving a coolant recirculation pump of a nuclear reactor, a frequency detection unit for detecting an output frequency of the inverter unit, and a high frequency signal from the frequency detection unit. In a variable frequency power supply device for a reactor coolant recirculation pump, which comprises a stop means for stopping the operation of the inverter unit by an input, the frequency detection unit includes a speed request signal at a maximum operating speed of the coolant recirculation pump. Of the first frequency detector that compares the set value with the output frequency by setting the set value in consideration of the fluctuation amount and the predetermined allowance, and sets a predetermined value equal to or less than the maximum allowable pump speed as an average set value, A second frequency detector that compares the average set value with the average value of the output frequencies within a fixed time, and an OR gate that receives the high frequency signal from each of the frequency detectors. Variable frequency power supply of the reactor coolant recirculation pump, characterized in that it comprises.