JPS6017077B2 - Output control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operating device, ie, an output control device, in an unstable region of a recirculation system of a boiling water nuclear power plant.

FIG. 1 is a block diagram showing the relationship between recirculation system equipment and a control system of a conventional boiling water nuclear reactor.

Output control of boiling water nuclear power plants is usually performed by variably adjusting the reactor core flow rate. This recirculation flow rate control is carried out in the reactor 1 as shown in Figure 1.
recirculation pump 3A installed in recirculation system piping 2A, 2B,
38 is driven by electric motors 4A, 4B, and the frequency of the power supply to the electric motors 4A, 48 is variably controlled by the variable frequency power sources 5A, 5B', thereby changing the rotational speed of the electric motors 4A, 4B. There is.

However, in the operating range of this recirculation system, the recirculation flow rate oscillates with a certain period within a certain flow rate range due to the characteristics of the equipment.

This oscillation of the recirculation flow rate causes oscillations in the core flow rate, which not only causes instability in the operation of the power system due to fluctuations in the output of the power plant and a deterioration in the quality of power, but also causes problems in the reactor core. This also caused the problem of high cycle fatigue caused by vibrations in the equipment.

For this reason, it has been necessary to take measures such as limiting the control range of the recirculation system and relying on the skilled operation of operators when the output increases at power plant start-up.

In view of the above points, this power plant has developed an operating system that automatically prevents oscillations in the recirculation flow rate even when the reactor output corresponds to the unstable region of the recirculation system that causes oscillations in the recirculation flow rate. This is intended to solve the conventional problems of power plant output vibration and high cycle fatigue of nuclear reactor equipment.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

As is clear from FIG. 1, the recirculation system of a boiling water reactor consists of two systems.

That is, the deviation device 11 receives the reactor load setting value signal 10B.
The deviation between the output of the reactor and the main steam flow rate signal 10A is calculated, and a deviation signal 11A is output to the main controller 8 of the recirculation control system.

The main controller 8 performs control calculations on the input deviation signal 11A to control the recirculation flow rate.
A frequency request signal 7A,
It is outputting 7B.

A block diagram of one embodiment of the present invention is shown in FIG. The operating device 20 according to the present invention inputs the frequency request signal 8A to the variable frequency power sources 5A, 5B, which is the output signal of the main controller 8 of the recirculation control system, and inputs the frequency request signal 8A to the variable frequency power sources 5A, 5B.
Frequency request signals 20A and 208 are output to controllers 6A and 6B, respectively, which control the frequency of .

FIG. 3 is a detailed block diagram showing the functions of the operating device 20 of the present invention.

The decision/command unit 21 inputting the frequency request signal 8A compares the lower limit PI and upper limit P2 of frequencies corresponding to the unstable region of the recirculation system with the signal 8A, and when the PI frequency signal 8A≦P2, the signal 8A is outputted via its output 21B. The contacts 23 and 26 are turned ON, and the contact 27 is turned OFF.

In other cases, the contacts 23 and 26 are off and the contact 27 is on.

Constant and bias signal generators 25 and 22 output constant frequency request signals P3 and P4, respectively.

The constant frequency request signal P3 satisfies P3<lower limit PI, and the constant frequency request signal P4 is set to (upper limit) P2-P3.

Next, the characteristics of the input signal 8A and output signals 20A, 20B of the operating device 20 according to the present invention will be explained using FIGS. 4a and 4b.

Figures 4a and 4b show variable frequency power supplies 5A and 5B in the vertical position.
0 to 100% is taken as the variable frequency range, and time (time t, to t4) is taken as the axis.

Therefore, PI~P2 percent (%
) is the unstable region of the recirculation system.

Now, the frequency request signal 8A is at time t, ~t4,
It changes as shown in Figure 4a. Therefore, in the conventional recirculation system control system, from the time when the frequency request signal 8A becomes P2 to the time 2 when the frequency request signal 8A becomes less than PI, and the time t when the frequency request signal 8A becomes PI again.
3 until the time when PaX becomes above, the recirculation system exhibits unstable behavior, causing the problems described above. However, in the recirculation system equipped with the operating device 20 according to the present invention, the required frequency signal to the controllers 6A, 68 of each variable frequency power source 5A, 5B is set to 2 between time t2 and time t4.
Since it is set as 0A and 20B, the influence of instability caused by the characteristics of the recirculation system equipment can be minimized.

That is, when the frequency request signal 8A intersects with P1 and P2, the operating device 20 according to the present invention changes the frequency request signal 8A into two frequency request signals 20A and 20B that exceed the unstable region width in a stepwise manner. Variable frequency power supply 5
It passes through the unstable region at a maximum response speed of A or 58 and obtains the above characteristics.

Thus, by applying the recirculation control system equipped with the operating device 20 according to the present invention, the unstable characteristics of the recirculation system equipment can be minimized, thereby reducing the instability of the power plant output and the atomic This not only makes it possible to minimize high-cycle fatigue of reactor equipment, but also improves the operational performance of nuclear power plants by expanding the operating range of the recirculation system and reduces the burden on operators.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the follower device, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a partially detailed view thereof, and Figs. 4a and 4b are explanatory diagrams of its operating characteristics. It is. 1... Nuclear reactor, 2A, 2B... Recirculation system piping, 3A, 3B... Recirculation pump, 4A,
48...The drive motor, 5A, 58...
...Variable frequency power supply, 6A, 6B... Its controller, 8... Main controller, 7A, 7B, 8A are its outputs, 10A... Main steam flow rate signal , 10B...
...Load set value signal, 11...1 with deviation device
1A is its output, 20... the operating device of the present invention,
21... Judgment command device, 21B is its output, 22
...Bias signal generator, 23, 26...
・・Normally open contact, 25 ・・・Constant signal generator, 27
・・・・・・Normally closed contact. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A pump that drives the flow rate of recirculation piping in a nuclear reactor, a variable frequency power source for an electric motor that operates the same, and its frequency control system are considered as one recirculation set, and a recirculation system is constructed from a plurality of recirculation sets. In boiling water nuclear power plants that make up
When a frequency request corresponding to the unstable region is issued to the frequency control system, from this request, each control system of the variable frequency power supply of the plurality of recirculation systems is adjusted to the unstable region without changing the total flow rate of the recirculation system. An output control device characterized in that it is provided with a driving device that emits an unbalanced frequency request signal with the frequency removed. 2. The operating device installed in the recirculation system includes a determination command unit,
a bias signal generation section, a constant frequency setting signal generation section,
Addition calculation section, ON/OFF control contact section, ON/OFF
The output control device according to claim 1, characterized in that the output control device is constituted by an F control contact portion. 3. In the judgment command section which inputs the frequency request signal from the main control section, when this request is within the unstable region of the recirculation system equipment, half of the sets among the plurality of recirculation sets are in the unstable region. The request signal is switched in the constant frequency signal generator using the ON/OFF control contact so as to output a constant frequency set value below the lower limit frequency as the request signal, and for the remaining half of the plurality of recirculation sets, 3. The output control device according to claim 2, wherein an ON/OFF control contact section is operated to add a bias signal output from a bias signal generation section to the frequency request signal.