JPS6019477B2 - Reactor recirculation flow control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear reactor recirculation flow rate control device, and in particular to a variable speed pump provided for feeding recirculated water into a nuclear reactor in a reactor recirculation system of a boiling water nuclear power plant. The aim is to improve the control characteristics of the variable speed electric motor that is the driving source for driving the motor.

Conventionally, the reactor output during normal operating conditions in boiling water nuclear power plants is controlled by the reactor recirculation flow rate.
The control of the recirculation pump drive variable speed electric motor of the reactor recirculation system, which controls the recirculation flow rate, is performed using the M-
This is done using the G set method.

This method uses a recirculation flow rate change signal 10 from the main controller 101.
When A is given manually or in automatic mode from the turbine EHC system, the speed controller 12 that receives the speed request signal 100 of the generator 24 from the main controller 10 operates as the scoop pipe position manipulator of the fluid coupling 23. 13, scoop pipe position change signal 12A
issue.

As a result, the rotation speed of the generator 24 changes, whereby the automatic voltage regulator AVRI1 controls the excitation of the generator 24, the generator output voltage is controlled, and the rotation speed of the recirculation pump motor 31 changes. and control the recirculation flow rate to the required value. However, the response characteristics of the M-G set are
3, scoop tube position controller 13, generator 24, exciter 21
The response characteristics are determined by the inertia of the recirculation pump and drive motors 30 and 31, and this is one of the limiting factors for the reactor power characteristics.

The present invention has been made in view of the above circumstances, and its purpose is to improve the response characteristics of the above-mentioned nuclear reactor recirculation system and pump drive variable speed motor control device. The purpose of this invention is to improve the output response characteristics of atoms. An example of the present invention will be described below in detail with reference to the drawings. A recirculation flow system of a boiling water nuclear reactor to which a flow rate control device according to the present invention is applied drives reactor recirculation water as shown in Fig. 2. A recirculation pump 30, a variable speed electric motor 31 supplying driving force to the pump, an M-G set which is a variable frequency power source for the electric motor, a scoop tube position operator 13 controlling the M-G set, and a speed controller. 1
2, a main controller 10, and an automatic voltage regulator 11.

The M-G set includes a driving electric motor 22 that rotates at a constant speed.
The main components are a fluid coupling 23 and a variable frequency generator 24, and an exciter 21 and a permanent magnet generator 20 for AVR power supply.
and a tachometer generator 25 for speed detection are directly connected. In order to obtain a predetermined reactor output, the reactor recirculation flow rate is controlled by changing the rotational speed of the recirculation pump 30 by changing the power frequency of the recirculation pump drive variable speed electric motor 31.

Although the above configuration is also seen in the case of the slave shown in FIG. 1, the present invention additionally provides a reactor recirculation flow rate control device indicated by the reference numeral 14.

This control device 14 receives as input signals a recirculation flow rate change signal 10C, a generator speed request signal 10D, and a generator output voltage signal 24A from the main controller 10.

The control device 14 controls the variable reactor 15 provided between the generator 24 and the pump drive motor 31 using the control signal 14A, and controls the input voltage of the recirculation pump drive motor 31 by controlling the reactive power consumed by the reactor. 4. This controls the motor output, ie the pump output, and thus the recirculation flow rate. However, the feature of this control method is that it does not cause step-out of the synchronous generator because it is a temporary control of the reactive power that is the output of the generator, and that it also controls the reactor and changes the input voltage of the drive motor. The M-G after reactor control has excellent long-distance response with almost no time delay.
The goal is to monitor the response of the set and, when a certain level of response is obtained in the generator output voltage, control the reactor to return to its original state.

Here, as shown in FIG. 3, the control device 14 includes an absolute change amount judgment circuit 40, a change direction judgment circuit 43, a reactor change amount judgment circuit 41, a reactor change number judgment circuit 42,
Switching circuit 46, generator output required voltage estimator 44
, response determination circuit 45, reactor short circuit device 47, reactor attached short circuit release device 48, and variable reactor 1
It consists of 5.

As another embodiment of the control device 14, as shown in FIG. 5, the time and change width control devices 52 and 53 can be combined.

The purpose of the reactor recirculation flow rate control device 14 is to control the response characteristics of the M-G set system to the recirculation flow rate request signal.
The purpose is to control the input terminal voltage of the variable speed motor driving the recirculation pump so that the required flow rate can be achieved in a short time.

Therefore, as shown in FIG. 3, the generator speed request signal 10D from the main controller 10 and the recirculation flow rate change request signal 10C
and the generator output terminal voltage signal 24A are input to the control device 14. Recirculation flow rate change request signal 10C
is input to the dead band absolute change amount judgment circuit 40 and the dead band change direction judgment circuit 43. The range of the dead zones e, e2 is set in advance based on the operating conditions so that the variable reactor 15 is not operated unnecessarily in response to minute changes in the output. The absolute amount judgment circuit 40 is for taking the absolute value of the recirculation flow rate change amount and converting it into the output of the drive motor 31, and is given nonlinear characteristics in consideration of the loss in the recirculation system. The output of the absolute amount judgment circuit 40 with dead band is
The signal is input to the reactor change amount determining circuit 41 as the requested motor output change signal 40A. The reactor change amount determination circuit 41 determines the absolute amount of change in the li factor, assuming that the motor output is proportional to the square of the motor input voltage, and that the output terminal voltage of the generator 24 and the impedance of the motor 31 remain unchanged during transient changes. Output as analog value.

This reactor change amount determination circuit output signal 41A is input to the reactor change number determination circuit 42, where the analog signal is converted into the number of reactors 15 to be changed (digital signal). The reactor 15 is composed of a plurality of reactors connected in series with short-circuit bypass circuits.

In the case of an increase in the recirculation flow rate, the reactor is short-circuited, the reactive power stored there is released, and the input voltage of the motor 31 is increased. Furthermore, in the case of a decrease in the recirculation flow rate, the short-circuited state of the circuit attached to the reactor is opened, and the input voltage of the electric motor 31 is reduced. In the normal operating state, the plurality of series short-circuited reactors 15 are divided into a short-circuit open state part for when the reactor power increases and an IJ actuator short-circuit part for the time when the reactor power decreases. The reactor change number determination circuit 42 issues a reactor change command to the switching circuit 46. The switching circuit 46 receives a change direction signal 43A from the change direction determination circuit 43 with a fuwaza band, and sends a reactor change command signal 42A to the reactor shorting device 47 when the recirculation flow rate increases, and sends a reactor change command signal 42A to the reactor short circuit device 47 when the recirculation flow rate decreases.
Switching is performed so that 2A is sent to the short circuit release device 48 attached to the reactor. Further, this switching circuit 46 automatically connects the input signal 45A to other devices 47 and 48 that are not connected to the reactor change command signal 42A. These devices 47 and 48 instantaneously operate the IJ actuator attached short circuit in accordance with the change direction in response to the reactor change command signal 42A.

As a result, the recirculation pump drive motor 31 which is the controlled object
input voltage changes instantaneously in response to recirculation flow rate change demands. As the input voltage changes, the output torque of the drive motor 31 changes, improving the initial response. On the other hand, the M-G set changes the generator speed and generator output terminal voltage in response to the generator speed request signal 100 in response to the recirculation flow rate change request from the main controller 10, and there is an error between the generator speed and the generator output terminal voltage. When the value falls within the range, it is necessary to return the reactor 15 to its original state. Here, to see the response of the M-G set, it is sufficient to judge the generator speed error signal of the speed controller 12.
The generator output voltage is controlled by the automatic voltage regulator AVR following changes in generator speed, and the AVR is controlled by the exciter 2
Since the output terminal voltage is controlled through two rotating bodies, the generator 1 and the generator 24, the generator output voltage changes with a time delay compared to the generator speed.

Therefore, the response of the MG set is determined based on the error between the generator output voltage and the required value. Note that the control device 14 is the main controller 10
The speed request signal 10D from the generator output voltage signal 24
In response to A, the automatic fin pressure regulator AVR controls the generator output voltage so that it is proportional to the generator speed (
V/HZ = constant control). However, the generator output voltage estimator 44 to which the generator speed request signal 10D is input estimates the generator output voltage after changing the recirculation flow rate, and inputs the output signal 44A to the response determination circuit 45.

The response determination circuit 45 inputs the generator output voltage signal 24A, determines the error between the output voltage and the required value, and determines the setting error e3,
When it enters the e4 range, it outputs an output signal 45A. Setting errors are reduced by the rate of change in generator output voltage and the rate of actuator restoration. Output signal 45 of response determination circuit 45
A is input to the device 47 or 48 in the restoration direction of the IJ reactor 15 through the switching circuit 46, and
5 is restored to steady state. Figure 4 shows the control characteristics of the reactor recirculation system and the MG set system.

The horizontal axis is the time axis. As shown in FIG. 4A, at time t, Fuwatai Sagi. Reactor recirculation flow increase signal exceeding 1
When 0C is input to the controller 14, a change in the pump drive motor input voltage in response to the recirculation pump input request is achieved almost instantaneously by shorting the reactor. Reactor change 1
As shown in FIG. 4B, 5A indicates the number of short circuit reactors when rising in the positive direction, and indicates the number of short circuit open reactors when falling in the negative direction. When the M-G set generator output voltage 24A changes in response to the load request from the main controller 10 and falls within the error range of e3 from the request, the short circuit release device attached to the actuator becomes 48 is operated and the reactor returns to a steady state. Recirculation pump drive motor input voltage 31A
As shown in Figure 4C, the voltage rises instantaneously due to the reactor short circuit, and continues to rise more slowly when the M-G set responds, but when the reactor returns to a steady state at a certain time, the input voltage 31A instantly increases. However, the requested value is restored by the M-G set response. The recirculation flow rate 33A to be controlled changes with a rise delay in response to the pump drive motor input voltage 31A. The control characteristics according to the current MG set method are shown by the dashed line. At time t3,
If the recirculation flow rate reduction signal exceeds the dead zone - e2, the control device 1
4, the reactor 15 receives a command from the control device 14 and instantaneously responds to the required amount of reduction, and the short circuit associated with the number of actuators is opened, and the input voltage 31A of the recirculation pump drive motor instantly changes to the required value. decreases to

The M-G set responds to a request from the main controller 10,
When the generator output voltage 24A decreases, the input voltage 31A of the pump drive motor also decreases further. At time D when the output voltage 24A of the motor responds within the error range of e4 from the required value, the reactor 15 returns to the steady state (FIG. 4D).
At the same time, the pump drive motor input voltage 31A increases stepwise, but settles to the required amount by the response of the M-G set. As with the increase in the reactor recirculation flow rate 33A, which is the control target, a response superior to the current M-G set system can be obtained (Fig. 4E). In the case of FIG. 5 as another embodiment of the control device 14, the operation is as follows as shown in FIG. 6 corresponding to FIG. 4.

Time control devices 52 and 53 are provided at the switching circuit input section, respectively.
to give time characteristics to the reactor operation. The controller 52 operates the 1' factor in several stages via a limiter to protect the electrical circuit against large changes in recirculation flow rate. Further, when the reactor returns to a steady state, the control device 53 performs detailed return control in multiple stages in consideration of the response of the M-G set. the result,
A smooth characteristic can be obtained when the pump drive motor input voltage 31A returns to the reactor steady state. As described above, according to the reactor recirculation control system of the present invention, in the control when the reactor recirculation flow rate changes due to changes in the reactor output, the control characteristics by the current M-G set can be changed to the reactor recirculation flow rate. Control of the pump drive motor input voltage may improve the initial response.

Since the power output of a nuclear reactor depends on the recirculation flow rate,... This control method improves the output characteristics of the nuclear reactor, and as a result, it is possible to effectively improve the load following characteristics of boiling water nuclear power plants expected in the future.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing a reactor recirculation system to which the present invention can be applied; FIG. 2 is a schematic system diagram showing an example of a reactor recirculation flow rate control device according to the present invention; Figure 4 is a block diagram showing its detailed configuration, Figure 4 is a signal waveform diagram explaining its operation, Figure 5 is a block diagram showing another example of the present invention, and Figure 6 is a signal waveform diagram explaining its operation. FIG. 10... Main controller, 11... Automatic voltage regulator (AVR), 12... Speed controller, 1
3...Scoop pipe position controller, 14...
Reactor recirculation flow rate control device, 15...Variable reactor, 20...Permanent magnet for AVR power supply, 21...
... Exciter, 22 ... Drive motor, 23
...Fluid coupling, 24...Variable frequency generator, 25...Tachometer generator for speed detection, 30
... Recirculation pump, 31 ... Variable remote motor, 40 ... Absolute amount of change judgment circuit, 41 ...
... Reactor change amount judgment circuit, 42 ... Reactor change number judgment circuit, 43 ... Change direction judgment circuit, 44 ... Generator output required voltage estimator, 45 ...
...Response judgment circuit, 46...Switching circuit, 47...Reactor short circuit device, 48...
...Short circuit release device attached to reactor, 52, 53
...Time, variation width control device. Tsutomu J figure Younger brother J figure 2 figure 3 Younger brother figure 4 figure 6

Claims (1)

[Claims] 1. A variable speed pump installed in the reactor recirculation system is driven at variable speeds by a variable speed motor controlled by a variable frequency power source to control the output of the reactor. In the control system, an attached short circuit is provided in the power supply path from the variable frequency power source to the variable speed motor, and further includes an absolute change amount judgment circuit, a reactor change amount judgment circuit, and a reactor change number judgment circuit, A variable control device comprising a reactor control device that short-circuits the reactor when the recirculation flow rate increases and opens the attached short circuit when the recirculation flow rate decreases, and a switching circuit that selects the recirculation flow rate increase operation or the recirculation flow rate decrease operation. 1. A reactor recirculation flow rate control device, comprising a reactor, and improving reactor output response characteristics by controlling the variable reactor according to a recirculation flow rate change request. 2. In the control device according to claim 1,
A nuclear reactor recirculation flow control device characterized by monitoring the response of the variable frequency power source and returning the variable reactor to a steady state before the change when the response is achieved to a certain extent. 3. In the control device according to claim 1,
A nuclear reactor recirculation flow rate control device characterized in that a limit is set on the number of instantaneous reactor changes in the reactor control device to perform time-limited reactor control.