JPS61246502A - Feedwater 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] [Field of Application of the Invention] The present invention relates to a water supply control device that controls the flow rate of water supply to a nuclear reactor, and in particular, to reduce fluctuations in reactor water level when switching feed water pumps and shorten the time required for switching. This invention relates to a water supply control device that enables

[Background of the invention]

Conventional nuclear reactor water supply control systems, especially those whose main challenge was to reduce fluctuations in the reactor water level when switching the operation of multiple water supply pump groups, include 1, for example, JP-A No. 5
No. 6-8597 is known. In this example, the change in the flow rate request signal of the water supply pump during manual operation is recorded on the input side of the water supply main controller.

By configuring the subtraction from the automatic flow rate request signal of the water supply system during automatic operation, the flow rate of the water supply pump during automatic operation can be increased or decreased by the amount of fluctuation in the flow rate of the water supply pump during manual operation, reducing fluctuations in the water supply flow rate. I'm trying to make it happen. In this case, fluctuations in the water supply flow rate are significantly reduced compared to the previous method where the flow rate of the manually operated pump was simply increased or decreased, and the flow rate of the pump during automatic operation was changed independently according to changes in the output of the main water supply controller. However, since the proportional relationship between the flow rate request signal of each pump and the actual pump flow rate does not always change during transient periods when the pump flow rate changes, there will be a difference in the fluctuation of the pump flow rate between automatic operation and manual operation. Mochiru. Similarly to the previous method, if ff1ft of the manually operated water supply pump becomes approximately the same as the flow rate of the automatically operated pump, the pump flow rate controlled by the water supply main controller output will be 1/1/1 of the water supply flow rate. 2, and it is considered that the control ability is reduced when a disturbance occurs.

Similarly, a known example that takes into account control when switching water pumps is Japanese Patent Application Laid-Open No. 58-217103. In this example, the rate of change of the flow rate request signal of the feedwater pump that is started/stopped for switching is corrected to reduce the deviation from the target value of the reactor water level if it is out of the set range. It has become so. However, due to the water level control characteristics of the reactor, there is a delay in the response of the reactor water level to changes in the feed water flow rate, so in this example, there is a possibility that fluctuations in the reactor water level will be larger than the deviation setting range. . For this reason, if the deviation setting range is narrowed to reduce fluctuations in the reactor water level, there will be more side stops that reduce the absolute value of the rate of change of the feedwater pump flow rate request signal, and the time required for switching will increase. There is a risk that it will be long.

[Purpose of the invention]

An object of the present invention is to provide a water supply control device that can reduce fluctuations in reactor water level by controlling the flow rate of each pump when switching the operation of a plurality of water supply pumps, and can significantly shorten the time required for switching. It is to provide.

[Summary of the invention]

For this purpose, the present invention is designed to keep the flow rate f of each pump constant by controlling the increase/decrease in the flow rate of each pump that is about to be switched, in order to keep the water supply flow rate constant.

The main steam flow rate and feed water i are the causes of fluctuations in the reactor water level.
In addition to the mismatch of t, in a boiling water reactor, it is possible that the void inside the reactor varies due to reactor pressure fluctuations, but since the fluctuations in reactor water level when switching the feed water pump are largely due to fluctuations in flood control flow rate, This system focuses only on the water supply flow rate and is designed to control it as described above. For this purpose, it is necessary to decrease or increase the flow rate of the water supply pump during automatic operation, which is controlled by the water supply main controller, by the amount of increase or decrease in the flow rate of the water supply pump that is about to be started or stopped. Therefore, a reactor water level deviation is generated to the water supply main controller so that the flow rate of the automatic operation pump decreases or increases at a constant rate of change, and the flow rate of the start/stop pumps is changed so that the sum of the flow rates of each pump is constant. In addition, in order to change the rate of change in the flow rate of the automatically operating pump, it is sufficient to control the rate of change in flow rate of the start/stop pump so that the reactor water level deviation changes. To achieve this kind of control, the rate of change in flow rate of the automatically operating pump or a process variable equivalent to this is taken in, compared with the target 1st shift, and the flow rate request signal of the start/stop pump is changed according to the deviation. The feedback control system may be configured by adjusting the rate.

When controlling as described above, it is necessary to control the flow rate change rate of the automatically operating pump to be constant.

This is equivalent to controlling the reactor water level deviation to a constant level based on input from the main water supply controller, and since the flow rate control of each pump contributes to stable control of the reactor water level, control stability against disturbance input can also be ensured. Dechiru.

[Embodiments of the invention]

The present invention will be explained below with reference to FIGS. 1 to 6.

First, the basic configuration of the water supply control system according to the present invention will be explained with reference to FIG. 1. In one example, the system is applied to a Mononoke boiling water nuclear power plant (hereinafter referred to as a BW plant). It is a matter of case.

As shown in the figure, the steam generated in the reactor pressure vessel 1 is passed through the main steam pipe and the steam control valve 5 provided midway through the main steam pipe to the turbine 2.
The atomizer 3 is thereby driven to rotate. On the other hand, the steam from the turbine 2 and the bypass valve 6 is condensed in the condenser 4, and then is injected into the reactor pressure vessel 1 again by the water supply pump 7.8 via the water supply 'i#. . There are two types of flood control pumps: one driven by a turbine (water supply pump 7) and one driven by a motor (water supply pump 8), and the flow rate of these water supply pumps 7.8 is controlled by the water supply control system [12] according to the present invention. It has become. Then, by adjusting the opening degree of the water supply regulating valve 10 provided on the discharge side of the motor-driven water supply pump 8 using the water supply regulating valve opening request signal 18, the water is guided to the water supply turbine 9 using the water supply turbine speed request signal 19. The flow rate may be controlled by adjusting the amount of steam drawn and adjusting the feedwater turbine speed. In addition, in the dX1 diagram, a turbine governor (El(G)) that receives the water supply turbine speed request signal 19 and controls the speed of the water supply turbine 9
is omitted.

By the way, the role of the water supply pump is divided into the motor and the drive water pump (hereinafter referred to as "power supply pump") up to the reactor output of 20 inches.

(referred to as MDRFP) 2 units + MD 几F'P-A, MDRF
P-E (spare)), one (MDRF'P-A
) is used, and one turbine-driven water pump (hereinafter referred to as TDRFP) is used from 20% output to 40% output (
TDRFP-A) is used, and two units (
TDRF'P-A, TDRFP-B) are now being used. The switching operation of the feed water pump is performed under the condition that the reactor output is constant when the reactor output reaches 20% and 40% when the reactor output increases or decreases.

Now, in this example, the feed water control device 12 takes in the reactor water level signal 15 from the water level detector 11 as an input, and outputs the feed water regulating valve opening request signal 18 and the water turbine speed request signal 19 by inputting the pump switching request. It is supposed to be done. As shown in the figure, the reactor water level signal 15 is compared with the target value signal from the water level target setter 13, and the water level deviation signal 16 is inputted to the main water supply controller 14 and the start/stop pump alk controller 20. Ru. The main water supply controller 14 takes in the water level deviation signal 16, performs proportional and integral calculations, and outputs the main water supply controller output 17, while the start/stop pump flow rate controller 20 receives the water level deviation signal 16 and the water main controller output 17. is taken in to create an estimated signal of the rate of change in flow rate of the pump during automatic operation, and the output 23 is changed so that this signal becomes equal to a given target value.

Start/stop pump flow controller output 23, as described below.
is equal to a of the start/stop pump and the quantity request signal, so the calculation content of the start/stop pump flow rate controller 20 is proportional to the difference between the flow rate change rate estimation signal of the automatic operation pump and the target value. A signal switch 21.22 as a two-flow rate request signal output device that performs calculations (or equivalent calculations) to create a flow rate request change rate setting signal for the start/stop pump and integrates this signal. is the water supply main controller output 17 or the start/stop pump flow 1 depending on the operator's selection operation.
This means that any one of the controller outputs 23 is selected and output as the water supply, A valve opening request signal 18, and water supply turbine speed request signal 19, respectively.

Next, to explain the water supply control device in detail, FIG. 42 shows a detailed block configuration of the first embodiment. The single-element/three-element switch 33 in the figure is set to the single-element side that takes in only the reactor water level signal 15 when the reactor output is up to 30%, and when the reactor output is 30% or more, it is set to the nuclear/p water level signal 15. , the mismatch signal of the feed water flow rate and the main steam flow rate is added via the coefficient unit 32 and is set on the three element side. In this example, TDR from MDR and FP-A operation at reactor power of 20 cm.
This is because we are assuming a switch to FP-A operation.

Single-element control is now performed. In this example, the flow rate change rate estimation signal of the automatically operating pump is generated by the pseudo differentiator circuit 4.
The transfer function of the pseudo-differential circuit 42 is expressed by the following equation.

However, S # K, T t are Laplace operator, conversion gain, and integral time constant of water supply main controller.

The output of the pseudo differential circuit 42 is determined by a signal corresponding to the rate of change of the main water supply controller output 17, and is proportional to the reactor water level deviation signal 16. The switching signal change rate controller 45 takes in the flow rate change rate estimation signal of the automatically operating pump, which is the output of the pseudo-differentiation circuit 42, that is, the deviation between the signal that determines the pump switching speed and its target value, and performs proportional, integral, and differential calculations. (
or equivalent calculation) to change the switching signal change rate 4.
6, and the switching signal change rate 46 is further integrated 547
The start/stop pump flow controller output 23 is obtained by integrating the start/stop pump flow controller output 23.

Now, to explain pump switching control, as a prerequisite for pump switching control, the water supply regulating valve-A opening request signal 3
8, water supply main control 4 output 17 by signal switch 34
is selected, and the t& amount of MDRFP-A is automatically controlled. On the other hand, the water supply turbine speed is increased by manual or computer control for TDR, F'P-A, and the pump discharge pressure is set at the outlet side of the water supply pump. The pressure has been increased to near the header pressure, and the minimum flow rate is in operation. From this state, if the signal switch 36 is operated to select the start/stop pump flow rate controller output 23 as the water supply turbine-A speed request signal 40, the water supply main controller output 17 will decrease at the target rate of change. The switching signal change rate controller 45 and the integrator 47 cause the water supply turbine-A speed request signal 4 to be
0 is increased, the outlet check valve of TDRFP-A opens, and the water supply to the reactor side increases. In this way, the water supply main controller output 17, i.e., the water supply regulating valve-A
This means that the increase in the water turbine-A speed request signal 40 is controlled so that the opening request signal 38 decreases at the target rate of change. By the way, the MDR and FP-A flow rate reduction and stop operations are performed when the main water supply controller output 17 and the start/stop pump flow rate controller output 23 become equal.

At the same time as the mutual control signals are switched by the signal switchers 34 and 36, the target value of the flow rate change rate of the automatically operating pump by the pump switching speed target setter 43 is changed to the opposite sign. While this causes the MDRFP-A flow rate to be reduced by the start/stop pump flow controller output 23.

The TDfLPP-AO flow rate is controlled by the main water supply controller 14 and increases. Eventually MD 几F
'When the flow rate of P-A becomes zero, the pump is stopped and placed in a standby state, and the signal switch 34 is switched to the automatic side to complete the pump switching control.

The above is the switching control when the reactor output is 20%, but when the reactor output is 40 yen and TDR and FP-B are additionally operated while TDFLFP-A is in operation.

Similarly, the flow rate of TDRFP-H is increased and controlled by the start/stop pump flow rate controller 20, and TDRFP-A and TDRFP-
When the control signals of B become equal, the signal switch 37 may be operated so that the TDRFP-B is controlled by the main water supply controller output 17. The transition from two TDR and FP operations to one operation and switching control from TDRFP-A to MDRFP-A at the time of reactor power drop can be performed by the reverse operation to that at the time of rise. Note that the signal switch 35 is for MDRFP-B.

FIG. 3 shows a detailed block configuration of the second embodiment of the water supply control device. This embodiment differs from that of Ml described above, in that instead of obtaining the flow rate change rate estimation signal of the automatically operating pump from the water supply main controller output 17 using a pseudo-differentiation circuit 42, the reactor water level deviation signal 16 is used as a coefficient. This point is obtained by passing through the device 48. Even with such a configuration, the water supply main controller 1
If the calculation in step 4 consists of only ordinary proportional and integral calculations, completely equivalent flow rate change rate estimation signals will be obtained and the control characteristics will not change in any way.

FIG. 4 shows a detailed block configuration of the third embodiment of the water supply control device. The difference between this embodiment and the first one is that in the latter, the control signal is completely switched to the flow controller side of the start/stop pump to control the pump flow rate for starting or stopping, whereas in the former Then, the water supply main control output 17 is connected to the start/stop pump flow rate controller output 23.
The point is that control is performed by adding .

When controlling in this way, start/stop pump flow rate controller output 23! It becomes a fi bias signal and changes the flow 'Ik request signal of the start/stop pump.The control characteristics will differ slightly when a disturbance is input that causes reactor water level fluctuation, but the basic control characteristics will not change. . M in this aspect
The switching control from DRF'P-A operation to TDaFP-A operation will be explained as follows.

That is, at the time when the flow rate of TDRFP-A starts to increase, startup/
Stop pump flow controller output 23 water supply turbine pin
A large negative bias signal is added to the water supply main controller output 17 by an adder 56 so that the A speed request signal 40 is minimized. As this bias signal decreases, T
Although the flow rate of DRFP-A increases, the it of both pumps becomes approximately equal at zero bias. At this point, the signal contact 50 is closed, the signal contact 52 is opened, and at the same time, the flow rate change target set by the pump switching speed target setter 43 is changed to the opposite sign. After this, the flow rate of MDRFP-A decreases, and eventually becomes flow t4, and the operation is switched to TDR and FP-A. The pump switching control is completed by stopping the MDRFP-A and putting it in a standby state, and opening the signal contact 50.

FIG. 5 shows the results of simulating the stone pump switching operation according to the prior art using a BWR plant dynamic characteristic simulator. In the prior art, fluctuations in the reactor water level are reduced by slowly switching pumps over several hours. However, here, in order to compare with the case according to the present invention, the control characteristics when switching the pump in a short time are shown as simulation results.

As shown in the figure, turbine-driven water pump-A (TDRFP)
It can be seen that the flow fjk of -A) increases rapidly due to the decrease in the flow rate of the motor-driven water supply bongoo A, resulting in a large rise in the reactor water level. The water supply main controller reduces the flow rate of the motor-driven water supply pump-A (MDRFP-A).

Since the control effect occurs with a delay, the response fluctuates overall and the reactor water level fluctuates widely.

FIG. 6 relates to an embodiment f41 of the water supply control device according to the invention. This figure shows the results of a similar pump switching simulation. As a result of the increase in the flow rate of TDaF'P-A, the feed water flow rate increased and the reactor water level rose.
P-A'7) The flow rate will be reduced by the water supply main controller. '1'DaFP-A's flow uVi water supply controller output is controlled to decrease at the target rate of change, so the rate of increase in flow rate temporarily decreases a few minutes after the start of switching, but after that The water supply flow rate is controlled to be constant and increases in accordance with the flow rate fluctuation of the MDRFP-A.

This result also shows that the water supply control device according to the present invention has a significantly shorter switching time than the conventional technology.
@It is possible to switch pumps while stably controlling the water level in the secondary reactor.

Although the water supply control device according to the present invention has been described as having an electronic circuit block configuration, it can also be realized by digital control means using a microcomputer or the like. In this case, the above description assumes that the operation is performed by the operator.

The contact switching operation during the pump switching control operation can also be completely automated by having the control means monitor other process quantities and determine the timing of the operation. Further, the start/stop pump flow rate controller according to the present invention mainly takes in a deviation signal between the target value and the rate of change of the flow rate request signal of the water supply pump during automatic operation, and outputs the change rate of the start/stop pump switching signal. A switching signal change rate controller that takes in the switching signal change rate and integrates 1. If you add upper and lower limiters to the output side of the switching signal change rate controller to limit the value of the switching signal change rate in the same way as a normal controller, The stability of control operation will be further improved. In this case, it is more effective to appropriately change the limiter setting value when the pump flow rate request signal increases and decreases. Furthermore, in the present invention, the change rate of the switching signal is determined by proportional, integral, and differential calculations; however, the present invention is not limited to these; for example, calculations by lead/lag compensation, fuzzy
) Similar effects can also be obtained by control calculations.

〔Effect of the invention〕

As explained above, in the case of the present invention, in addition to fluctuations in the reactor water level, there is a function to monitor fluctuations in the flow 11 request signal of each pump and control the rate of change in flow rate of the pumps to be started or stopped. Therefore, fluctuations in the water supply flow rate can be prevented. In the prior art, the pump is started or stopped for water pump switching.

There may be a difference in the amount of change in the flow rate between the water supply main controller and the pump whose flow rate is automatically controlled.In such cases, the water supply flow rate changes and the reactor water level fluctuates. However, in order to prevent this, the flow rate of the switching pump was changed gradually over a long period of time to suppress fluctuations in the reactor water level. Therefore, whereas in the past, switching operation of the water supply pump took several hours, in the case of the present invention, switching can be performed within several tens of minutes, which has the effect of significantly shortening the required time. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic outline configuration of a water supply control device according to the present invention, FIGS. 2, 3, and 4 are diagrams showing the configuration of an embodiment thereof, and FIG. 5. FIG. 6 is a diagram showing an example of the simulation results of the pump switching control characteristics so far and the simulation results according to the present invention. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 7... Turbine-driven water supply pump, 8... Motor-driven water supply pump, 9... Water supply turbine, 10... Water supply adjustment valve, 11... Water level detector, 12... Water supply control device, 13... Water level target setter, 14... Water supply main controller, 20... Start/stop pump flow rate controller, 21.22... Signal switch, 34, 3
5, 36° 37... Signal switch, 42... Pseudo differential circuit, 43... Pump switching speed target setter, 45...
・Switching signal change rate controller, 47... Integrator, 48...
・Coefficient unit, 5o. 51.52, 53...Signal contacts, 54,55,56°57...Adder.

Claims (1)

[Claims] 1. A water supply control device that controls a plurality of water supply pumps provided to supply water to a nuclear reactor, which controls the flow rate of water supply to the reactor based on the deviation of the reactor water level from a target value. Changes in the flow rate request signal of the water supply pump during automatic operation from the water supply main controller by taking in either the deviation between the target value of the reactor water level and the output of the water supply main controller that controls the water supply main controller. a start/stop pump flow controller that varies the flow request signal of the start/stop pumps so that the rate is equal to a target value; and a flow request signal to each feedwater pump based on the output of the controller and the output of the water main controller; What is claimed is: 1. A water supply control device comprising: a flow rate request signal output device that provides a flow rate request signal output device, and configured to control the flow rate of each feed water pump without changing the reactor water level when switching the feed water pumps. 2. The rate of change of the flow rate request signal of the water supply pump during automatic operation is:
2. The water supply control device according to claim 1, wherein the water supply main controller output is obtained by passing the output through a pseudo differentiation circuit. 3. The rate of change of the flow rate request signal of the water supply pump during automatic operation is:
2. The water supply control device according to claim 1, wherein the deviation of the reactor water level from the target value is obtained by passing through a coefficient unit. 4. Start/stop pump flow rate control includes a switching signal change rate controller that takes in the deviation from the target value of the change rate of the flow rate request signal of the water supply pump during automatic operation and performs proportional, integral, and differential calculations, and a change rate controller that performs proportional, integral, and differential calculations. 2. The water supply control device according to claim 1, comprising at least an integrator that integrates the output of the controller and outputs the output of the start/stop pump flow rate controller. 5.The flow rate request signal output device is the water supply main controller output, start/
Claim 1, which is a signal switching device that selectively outputs either one of the stop pump flow rate controller outputs for each water supply pump.
Water supply control device as described in section. 6. The flow rate request signal output device is comprised of a signal contact corresponding to the water supply pump and an adder corresponding to the water supply pump that adds the start/stop pump flow rate controller output from the contact to the water supply main controller output. Water supply control device according to scope 1.