JPS6214046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water supply control device for a boiling water nuclear power plant, and particularly when switching between multiple water supply systems.
The present invention relates to a water supply control device that can switch water supply systems without affecting reactor water level.

The water supply system of a boiling water nuclear power plant is equipped with two turbine-driven water pumps with 50% capacity and two motor-driven water pumps with 25% capacity to compensate for the drop in reactor water level due to the steam generated in the reactor. , this is switched according to the reactor output to supply water from the condenser to the reactor and maintain the reactor water level at a constant level.

The control device that controls the water supply flow rate of this water supply system is
For a certain set value Lo of the reactor water level, only the reactor water level L of a single element, or the reactor water level L of three elements,
This system feeds back the feed water flow rate Fw and main steam flow rate Fs, and provides flow signals for each feed water system using PID controller 1 (proportional, differential, and integral controllers) to maintain the reactor water level at a constant set value Lo. be.

Figure 1 shows the behavior when the water supply system is switched by this water supply control device, and shows the changes in the flow rate F ₁ of the newly operated water supply system, the flow rate F ₂ of the stopped water supply system, and the reactor water level L with respect to time t. represents. This water supply system switching operation does not cause large fluctuations in the reactor water level L, so until time To, F ₁ is gradually increased using the corresponding M/A switching manual setting device, and after time To, F _{1 is} increased.
is automatic and _F2 is manual, and _F2 is gradually decreased using the manual setting device of the corresponding switch.
The water supply control system shown in the figure does not take into account the influence of the flow rate from the manual setting device of the M/A switch, so this influence causes fluctuations in the reactor water level as a disturbance.
The fluctuations in the reactor water level L shown in FIG. 2 are unavoidable.

For this reason, the switching operation of the water supply system is generally performed over several hours to avoid large fluctuations in the reactor water level.
It was necessary to operate the A switch, which was the critical path when starting up the reactor. On the other hand, when switching the water supply system in a short period of time, large fluctuations in the reactor water level L are unavoidable, and fluctuations in the reactor water level have a large negative impact on the fuel in the reactor core and the turbine system, and the water supply system The switching operation was considered to be the most difficult operation.

As described above, the present invention eliminates the drawback of conventional water supply control devices that unavoidably causes fluctuations in the reactor water level when switching the water supply system, and enables the water supply system to be changed in a short time without causing fluctuations in the reactor water level. The purpose of the present invention is to provide a water supply control device that can be switched.

An embodiment of the present invention will be described with reference to FIG. In FIG. 2, the single element/three element switch 23 uses a proportional calculator to convert the mismatch between the feed water flow rate Fw and the main steam flow rate Fs into the reactor water level signal L when a single element is selected, and the reactor water level setting signal L when three elements are selected. The signal obtained by adding the correction K (Fw-Fs) converted to the water level in step 25 is given to the adder 22. And in the adder 22, Lo-K (Fw-Fs)
get. On the other hand, pseudo-differentiation circuits 36, 37, 38,
39 are water supply turbine speed controllers 32, 3, respectively.
3. Motor-driven water supply pump flow control valve controller 3
If the flow rate request signals to the flow rate controllers 4 and 35 are inputted, and the output of each differential circuit is inputted to the PID controller 21, the output of the PID controller 21 will mismatch with the flow rate request signal. so that it disappears. Also, the switching devices 40, 41, 42, 4
3 each has a contact that operates in conjunction with the automatic/manual switching contact of the M/A switch 28, 29, 30, 31, and the contact is closed when the corresponding M/A switch is manual, creating a pseudo differential circuit. 36, 37, 38, 39
The output is given to the adder 44. An adder 44 subtracts the signals of each switch 40, 41, 42, and 43 from the difference between the reactor water level setting signal Lo from the adder 22 and the single-element or three-element feedback signal, and subtracts this signal.
Input to PID controller. As a result, the PID controller calculates M/
The A switch calculates the water supply flow rate by subtracting the water supply flow rate manually injected, that is, the M/A switch calculates the water supply flow rate automatically injected. The switch 27 performs manual and automatic switching of the PID controller, and is normally operated automatically. The M/A switchers 28, 29, 30, and 31 switch each water supply system between automatic and manual.
A manual flow rate request signal set by the A switch is applied to the feedwater turbine speed controllers 32, 33 and the motor-driven feedwater pump flow control valve controllers 34, 35.

FIG. 3 shows a water supply system for a boiling water nuclear power plant using the water supply control system of the present invention. The water supply flow rate to the furnace 51 is controlled, and the motor-driven water supply pumps 57 and 58 are operated by flow control valves 59 and 6, respectively.
0, the feed water flow rate is controlled by the controllers 30 and 31, and the drop in the reactor water level due to the steam generated in the nuclear reactor 51 for driving the turbine generators 52 and 53 is compensated for.

Next, it will be explained with reference to FIG. 4 that according to the water supply control device according to the present invention, the reactor water level does not fluctuate even when switching the water supply system by performing the same operation as in the conventional method.

By starting up a newly operated water supply system and gradually increasing its flow rate request signal using the manual setting device of the M/A switch, the flow rate F ₁ of this water supply system increases, but the water supply control according to the present invention In the device, at the same time as F ₁ increases, this increasing signal causes the pseudo differentiator circuit, switch, and adder 44 to decrease the automatic flow rate request signal of the water supply system that had been selected up to that point, so that the flow rate F ₂ of that water supply system increases. The total water supply flow rate will not change significantly. Then, the M/A of the water supply system is newly operated without causing any fluctuation in the reactor water level L.
It is possible to match the manual and automatic flow rate request signals of the switch. Also, at time To, the M/A switch of the newly operated water supply system is set to automatic, the M/A switch of the previously selected water supply system is set to manual, and the latter water supply system is set to the M/A switch of the water supply system that has been selected. By gradually decreasing the flow rate request signal using the manual setting device,
The flow rate F ₂ of this water supply system decreases, but this decrease signal increases the automatic flow rate request signal of the newly operated water supply system automatically by the adder 42, so the flow rate F ₁ increases and causes fluctuations in the reactor water level. It becomes possible to switch the water supply system without having to supply water. Furthermore, since automatic and manual switching of the M/A switch is performed when there is no fluctuation in the water level and the flow rate request signal is stable, it is possible to perform the switching without causing sudden fluctuations to the water supply system.

As described above, by using the water supply control device according to the present invention, the switching operation of the water supply system can be performed in a short time and without causing fluctuations in the reactor water level.

[Brief explanation of the drawing]

Figure 1 is a response diagram of the water supply flow rate and reactor water level when switching the water supply system using a conventional water supply control device, Figure 2 is a block diagram of the water supply control device according to the present invention, and Figure 3 is a diagram of a boiling water nuclear power plant. FIG. 4 is a conceptual diagram of the water supply system of the present invention, and FIG. 4 is a response diagram of the water supply flow rate and reactor water level when the water supply system is switched by the water supply control device of the present invention. 21...Water supply main controller (PID controller), 22...Adder, 23...Single element/three element switcher, 24...Adder, 25...Proportional calculator, 26...Adder, 27...Water supply controller automatic /Manual switch, 28, 29, 3
0, 31... M/A switch, 32, 33... Water supply turbine speed controller, 34, 35... Motor-driven water supply pump flow rate control valve controller, 36, 37, 38, 39
...pseudo differential circuit, 40, 41, 42, 43...M/
Interlocking contact with A switch.

Claims (1)

[Claims] 1. In a boiling water nuclear power plant with multiple water supply systems to the reactor, there is a reactor water level controller to keep the reactor water level constant, and an automatic flow rate request signal from the reactor water level controller or manual flow rate setting. An M/A switch that switches one of the signals to provide a flow rate request signal for each water supply system, a calculator that calculates the flow rate setting signal for the water supply system during manual operation, and an automatic flow rate request for the water supply system during automatic operation. an adder that subtracts the flow rate setting signal of the manual water supply system calculated by the arithmetic unit from the signal, and increases or decreases the flow rate of the water supply system during automatic operation by the amount of variation in the flow rate of the water supply system during manual operation; M/A
A water supply control device characterized in that when a switch is switched between manual and automatic switching, the water supply system can be quickly switched without changing the reactor water level by compensating so that this effect does not occur.