JPS6287895A - Core flow controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a core flow rate control device for controlling the core flow rate in a boiling water nuclear power plant.

[Technical background of the invention and its problems] For example, in a boiling water nuclear reactor, a so-called M/G set is used to control a coolant-driven pump.

This is a fluid coupling installed between the AC generator drive motor (hereinafter referred to as M/G set drive motor) and the AC generator fi (hereinafter referred to as M/G set generator). The connection state of the fluid coupling changes and M
/ From G set? Since the rotational speed of the 11 machines changes, a variable frequency AC power source is obtained, and the core flow rate of coolant is adjusted by using it as a power source for a pump drive motor that is directly connected to the pump. However, this M/G
The problem is that the flow rate of the coolant cannot be changed rapidly due to the presence of large inertia forces in the sector.

Figure 2 shows an example of a core flow control system using a conventional M/G set.
When the speed controller 1 outputs a request to increase the pump speed, that is, increase the coolant flow rate, the scoop pipe operating device 2 causes the scoop between the fluid couplings 3 to +L? 4 is inserted and the fluid coupling 3
The bond between is made tighter.

One side of the fluid coupling 3 is driven at a constant speed by an M/G set drive motor 5, and the other side is connected to an M/G set generator 6. Further, the M/G cellar 1-generator 6 is connected to a pump drive motor 8 that directly drives a pump 7.

Therefore, by making the connection of the fluid coupling 3 tighter, M
/G set The rotation speed of the generator 6 increases.

The coolant flow rate will increase. Further, the excitation current of the M/G set generator T8 machine 6 is controlled by an excitation current control system 9 so that the ratio between the generator output voltage and the AC frequency, that is, the generator rotation speed, is constant.

However, such an M/G set has a problem in that a large inertial force exists in the M/G set, and it is illegal to rapidly change the flow rate of the coolant solely by manipulating the scoop tube.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to quickly adjust the core flow rate without being affected by the inertia of the M/G set when changing the core flow rate in a boiling water nuclear power plant. The object of the present invention is to provide a core flow control device that can be changed to

[Summary of the invention]

In order to achieve the above object, the present invention provides an ft! power supply in which an alternator driving motor and an alternator are supplied from a variable frequency power supply device coupled by a fluid coupling. In a core flow control system configured to adjust core flow using a recirculation pump controlled by a source, a speed request signal of the recirculation pump is input to a core flow compensator, and a speed request signal of the recirculation pump is input to a core flow compensator. The excitation current of the alternator of the variable frequency power supply is changed by applying an output signal to the excitation current control system of the variable frequency f4g device, thereby controlling the recirculation pump and controlling the core flow rate. It was designed to be adjusted.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a block diagram of a core flow rate control device for a boiling water nuclear power plant according to the present invention. with speed controller.

Since the M/G set generator consists of a core flow compensator 10 for changing the excitation current of the stable machine, the same components as the conventional ones are given the same reference numerals and detailed explanations thereof will be omitted. do.

By the way, to explain the operation of the flow rate compensator 10 in t), the excitation current change signal S2 is outputted depending on the change in the pump speed request signal S1.
The excitation current is only temporarily changed and gradually recovered to zero, and the excitation current is changed only when improving the initial response of changing the cardiac flow rate. This is because the excitation current of the M/G set generator 6 is normally adjusted so that the ratio of the generator output voltage to the AC frequency is constant. This is because it is controlled by the flow controller 9.

As the transfer function of the flow rate compensator 10, for example, "-" can be considered.

L+TS Here, Knigain T: Time constant SNilaplus operator Next, to explain the operation of this embodiment, when the pump speed request signal S1 increases (or decreases), the excitation current change signal S2 is sent from the core flow rate compensator 10. It is output and guided to the excitation current control system 9 to request an increase (or decrease) in the excitation current.

When the excitation current increases (or decreases), the electromotive force of the M/G set generator 6 increases (or decreases), and the generating end voltage, that is, the inlet voltage of the pump drive motor 8 increases (or decreases). Since the excitation current is controlled using a thyristor, the time delay in the change in the voltage at the generating end in response to the demand can be ignored. Therefore, the inertial force is only applied to the pump drive motor 8 and the coolant drive pump 7, and cooling is performed. It becomes possible to change the coolant flow rate of the material-driven pump 7 at high speed. The relationship between torque and slip for the pump drive motor 8 is shown as follows, with slip on the horizontal axis and torque on the vertical axis.
The result will be as shown in the figure. Here, since the torque is proportional to the square of the input terminal, increasing (or decreasing) the excitation current results in M/
The output voltage of the G-set generator 6 increases (or decreases), and the torque curve changes from a to b (or C) in the figure, and the drive torque of the pump drive motor 8 immediately increases (or decreases). However, as the rotational speed increases (or decreases), the coolant flow rate of the coolant drive pump 7 increases (or decreases). After this, the excitation current change signal S2 gradually recovers to zero by the core flow compensator 10, but at the same time, the scoop pipe operation signal S3 from the speed controller 1 increases (or decreases), so the fluid coupling 3, the driving torque for the M/G set generator 6 increases (or decreases), and both cancel and settle at a predetermined value.

The song shown in Figure 4! ! d shows the response when the pump speed request signal s1 is changed by an amount equivalent to 3% of the core flow rate, and it can be seen that the initial response is improved compared to that of the conventional control system shown by curve aa in Figure 5. .

〔Effect of the invention〕

As explained above, according to the present invention, the output voltage of the M/G set generator changes by changing the excitation current of the M/G set generator when changing the core flow rate in a boiling water nuclear power plant, This changes the drive torque of the recirculation pump drive motor and changes the number of revolutions, but
Since these are not affected by the inertia of the M/G set, the initial response when changing the core flow rate can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional core flow rate control device, and FIG. 3 is a diagram showing torque and slip of a pump drive motor of an M/G set according to the present invention. Figure 4 is a diagram showing an example of the response when the core flow rate is changed by the core flow rate control device of the boiling water nuclear power plant shown in Figure 1. Figure 5 is a diagram showing the response example of the core flow rate changed by the core flow rate control device of the boiling water nuclear power plant shown in Figure 1. It is a figure which shows the example of a response at the time of a flow rate change. 1 Speed controller 2 Scoop tube operator 3 Fluid coupling 4 Scoop tube 5 M/G set drive motor 6 M/G set generator 7 Pump 8 Pump drive motor 9 Excitation current control system 10 Core flow rate compensator (8733) substitute Person Patent Attorney Yoshiaki Inomata (Haga1
name) Fig. 3 No. 51;・1

Claims (1)

[Claims] (1) The alternator drive motor and the alternator are configured to adjust the core flow rate using a recirculation pump controlled by power supplied from a variable frequency power supply unit coupled by a fluid coupling. In the core flow rate control device, the speed request signal of the recirculation pump is input to the core flow rate compensator, and the output signal of the core flow rate compensator is applied to the excitation current control system of the variable frequency power supply device, thereby controlling the variable frequency. A reactor core flow rate control device, characterized in that the excitation current of an alternating current generator of a power supply device is changed, thereby controlling the recirculation pump and adjusting the core flow rate.