JP6045367B2 - Reactor feed water flow control device - Google Patents

Description

  The present invention relates to an apparatus for controlling the flow rate of water supplied to a nuclear reactor of a boiling water nuclear power plant, and particularly in a transient state where the nuclear reactor is operated at a low output, the operation mode is changed when there is a reactor water level deviation. The present invention relates to a reactor water supply flow rate control device that can reduce the load on an operator more safely even if the gain for control is changed and changed.

Conventionally, the control of the reactor water level in a boiling water nuclear power plant has been performed using three elements: the flow rate of steam generated in the reactor, the reactor water level, and the feed water flow rate to the reactor.
The prior art will be described with reference to FIG.
In a boiling water nuclear power plant, water (cooling water) is supplied into a nuclear reactor 50 by a feed water pump 52 via a feed water pipe 53. Nuclear fuel is loaded in the nuclear reactor 50, and steam is generated from the cooling water by the heat generated from the nuclear fuel. The steam is supplied from the nuclear reactor 50 to the turbine (not shown) via the main steam pipe 56 to generate power. The machine is driven to generate electricity. The steam that has worked is introduced into a condenser (not shown) to become condensate, which is supplied again. Further, around the reactor 50, there is a reactor purification system 51 that removes impurities and the like of cooling water inside the reactor 50 at the time of start-up and normal operation, and this reactor purification system 51 is provided with a CUW dump valve 57. It has been. This CUW dump valve 57 is used to open the plant at the time of starting the plant and drain the cooling water in the reactor 50.
The nuclear fuel is arranged in the lower part inside the reactor 50, and a structure such as a steam separator and a steam dryer for taking out the dried steam is arranged in the upper part. It needs to be controlled within a certain width.
Therefore, as described at the beginning, control by so-called three elements is performed.
Specifically, the control is performed using the reactor water supply control system 11. In this reactor water supply control system 11, the water level signal 2 from the reactor 50, the feed water flow signal 7 from the feed water flow meter 54 installed in the feed water pipe 53, and the main steam flow meter installed in the main steam pipe 56. 55, a difference signal between the water level deviation signal calculated from the water level signal 2 and the water level setting signal, and the mismatch flow rate signal calculated from the feed water flow rate signal 7 and the main steam flow rate signal 7 Is an input signal to the flow controller. In the flow rate controller (PID controller), a compensation calculation using a proportional gain, an integral gain, and a differential gain is performed to generate an output signal as a flow rate control signal, and this is used to supply a feed water pump 52 provided in the feed water pipe 53. And the opening of the feed water flow rate adjustment valve 4 are controlled.
Furthermore, the boiling water nuclear power plant has an operation mode that matches the operation state, and if the operation mode is different, the water level control differs depending on the water level required for the reactor 50, so the above-mentioned gain is also different. .

Thus, for example, in the “reactor water supply control device” disclosed in Patent Document 1, the proportional gain, integral gain, differential gain, and function with respect to the input signal are set according to the flow rate signal of the water supply pump and the number of operated water pumps, in particular. And a variable gain setting device and a variable function setting device for controlling.
As a result, stable water supply flow rate control can be performed using an optimal control gain and function according to all operating conditions.

Further, in Patent Document 2, the reactor feedwater pump is named “Reactor feedwater pump flow control device” and the reactor feedwater pump is input to the flow rate controller (PID control device) in consideration of when the reactor feedwater pump is stopped. In addition to the pump request signal when the pump stops, the difference signal between the feed water flow request signal and the feed water pump flow signal or the pump request signal is input, and the proportional, integral, and differential operations are performed, and this operation signal is used as the pump request signal. It has a differential operation stop device that outputs from the flow rate controller and stops the differential operation when the pump is stopped.
In this patent document 2, when the reactor feedwater pump is stopped, stable control is achieved by stopping the differential operation that may cause a large gain by using the pump request signal without using the feedwater pump flow rate signal. Is possible.

Finally, in Patent Document 3, in the control using the above-mentioned three elements with the name “reactor water supply control device”, a mismatch gain that converts the main steam flow rate and the feed water flow rate signal into a water level signal is set as a recirculation pump runback, A technique is disclosed in which when a recirculation pump trip, a feed water pump trip, or a reactor scram occurs, the mismatch gain setting device is used to increase the feed water flow rate to a smaller amount than the actual feed water flow.
This technology makes it possible to minimize the occurrence of unnecessary trips and alarms, shortening the stabilization time of the reactor water level, reducing the burden on the operator, and improving the operating rate of the plant. It is possible.

JP-A 64-16993 JP 59-109933 A Japanese Patent Laid-Open No. 5-52991

  However, in the invention disclosed in Patent Document 1, it is rather complicated to change the proportional gain, integral gain, differential gain, and function according to the flow rate signal of the feed water pump and the number of operated feed pumps. It was difficult to cope with this event, and there was a problem that it took time and cost to design the plant. Moreover, it is necessary for the operator to recognize that the setting has been changed, the burden on the operator is large, and it has not always been easy to cope with plant operation.

  The invention disclosed in Patent Document 2 is also considered to be an effective invention when the water supply pump is stopped. However, since the water supply pump is stopped in the first place, the idea of controlling this is impossible. It is believed that there is. Moreover, in order to add a pump request signal when the reactor water pump stops to the input signal, it is necessary to change the conventional control method, resulting in a mental burden and cost increase for the operator, and further, around the reactor There is a problem that it has a large influence on the design of other equipment and may also affect safety. In addition, ordinary boiling water nuclear power plants have two turbine-driven feed pumps that use steam and two motor-driven feed pumps that use electric motors. Although it is very limited, the water level control in the state where the water supply pump is decelerating is more difficult and the burden on the operator is large, but there is a problem that this technique cannot be solved.

  In the invention disclosed in Patent Document 3, the main steam flow signal and the water supply are not considered only when the feed water pump is stopped as in Patent Document 2, but the recirculation pump runback (deceleration operation) is also considered. Since the mismatch gain for converting the flow rate signal to the water level signal is increased to shorten the settling time of the water level compared to the actual level, the transient phenomenon is not eliminated gradually, so to address it by a sudden change. This means that in the event of an unexpected event, the operator is likely to take away the time and mental leeway to respond, and the burden is large and disruptive. There was a drawback that it could cause errors and had a significant impact on safety.

Hereinafter, a new boiling water reactor will be described as an example. In the new boiling water reactor, the recirculation pump used in the techniques disclosed in Patent Documents 1 to 3 is not adopted, and an internal pump is installed at the bottom of the reactor. Yes. Further, the flow rate controller used for the reactor water supply flow rate control is a PI controller that uses only a proportional action and an integral action and does not employ a differential action.
In the operation of this new boiling water reactor, the turbine trips, the turbine-driven feed pump also trips, and the internal pump is run back and only the motor-driven feed pump is driving. In this case, when the reactor water level rises, as described in the prior art, the input signal is used to lower the water level in order to protect the structures existing at the top of the reactor. Is input to the flow controller. At that time, the operator may manually open the CUW dump valve 57 of the reactor purification system (CUW) 51 in order to promote the lowering of the water level. In such a case, since the CUW dump valve 57 is opened, the activation of the reactor purification system 51 is permitted, and the permission signal 7 is input to the reactor water supply control system 11 so that the flow rate is increased. When the controller is operating automatically, a change from the low power operation mode to the (reactor) start-up mode will be made.
Thus, when there is a change to the start mode, the gain is switched to a gain different from the low output operation mode. In particular, when the gain of the proportional operation is switched, the output signal temporarily fluctuates greatly due to the fluctuation of the gain. In contrast to the event, the output signal is an output signal that works to raise the water level, which puts a great mental burden on the operator and makes stable plant control difficult.
Furthermore, the difference in gain (which is smaller in this case) is based on the manual operation of the operator and is an event that is not expected in automatic operation. Thus, it is very difficult to correspond to the gain as in Patent Document 1.
In addition, the demand for the water supply pump is low when the turbine-driven water supply pump is stopped at the time of low output operation and the water supply pump is operating at a low flow rate such that one or two motor-driven water supply pumps are operating. It is more efficient and stable to control the feed water flow rate control valve than to output a signal, and there is also a problem that effective reactor water level control is required with as little change and improvement as possible.

  The present invention has been made in response to such a conventional situation, and an object of the present invention is to control the operation mode when the reactor water level is rising in a transient state where the reactor is operated at a low output. Reactor feedwater flow rate control system that can reduce the load on the operator more safely even if the gain for the engine fluctuates and can be stably controlled with minor additions and improvements to the existing nuclear power control system It is to provide.

In order to achieve the above object, a reactor water supply flow rate control device according to the first aspect of the present invention uses a difference between a water level setting signal and a water level signal of a reactor of a boiling water nuclear power plant as an input signal, and the input signal is proportional A proportional operation circuit that generates an operated component; and an integration operation circuit that generates a component obtained by performing a unit time integration operation on the input signal; and a unit operation that performs a proportional operation on the input signal and the unit time integration operation. ingredients added together to generate an output signal, a reactor feedwater flow control device for controlling the opening of the water supply flow control valve in the low power operation in the output signal, the by changing operating modes of the reactor when the gain for the proportional action is changed reduced, a switch for interrupting the supply to the output signal of the component by at least the proportional action of the integral action and the proportional action, the switch It is characterized in that to time blocked from the start to the end of reducing change in gain for the proportional action.
In the invention having the above-described configuration, the opening degree of the feed water flow rate control valve is controlled in a situation where it is difficult to control the feed water pump during low output operation. At that time, if the difference between the reactor water level setting signal and the water level signal is a negative value (water level setting signal <water level signal), the water level is controlled to be lowered. However, when the gain for proportional operation is decreased and changed, the proportionally operated component is increased, so that the water level is controlled to increase. Conversely, if the difference between the reactor water level setting signal and the water level signal is a positive value (water level setting signal> water level signal), the water level is controlled to rise, but the operation mode changes at that time. If the gain for proportional operation is decreased and changed, the proportionally operated component is decreased, so that the water level is controlled to be lowered.
In view of this, the invention according to claim 1 acts to cut off the supply of the component to the output signal by at least the proportional action for the time from the start to the end of the gain reduction change.

Invention is a reactor feedwater flow control device according to claim 2, there is provided a reactor feedwater flow control device of claim 1, the circuit of the input signal is branched at the branch point, said one of the branch side a proportional operation circuit, the integration operation circuit in the other branch side, as well as connected in parallel, by adding the signal by connecting with the confluence of the downstream side of the proportional operation circuit and said integration operation circuit, downstream A feedback circuit for feeding back the output signal is connected to the output signal before the unit time is added, and a command signal for changing the gain for the proportional operation is provided upstream of the branch point via a negative circuit. or wherein the merging point a downstream provided with the switch upstream of the connection point between the feedback circuit, the time from the start to the end of the reduction changes the gain for the proportional operation, the proportional operation The supply to the minute and the output signal of the unit time integral action component is characterized in that blocked by the switch.
In addition to the same operation as that of the first aspect of the present invention, the proportional operation circuit operates so as to perform a proportional operation, and the integral operation circuit operates so as to perform an integral operation per unit time. Since the integration operation circuit performs the integration operation for the unit time, the components of the integration operation up to the unit time before are added by feeding back the output signal. That is, the feedback circuit acts to feed back the component of the proportional operation and the component of the integral operation. Also, the fact that the proportional operation circuit and the integration operation circuit are connected in parallel acts to calculate the proportional operation component and the integral operation component independently of the input signal.
Further, when there is a command signal for changing the gain for proportional operation, the negation circuit negates this command signal, so that no switch signal is generated. Therefore, when the switch is left open and installed upstream from the branch point, the input signal is not input to the proportional operation circuit and the integration operation circuit, and the calculation is stopped. Further, when it is installed downstream from the junction and upstream from the connection point with the feedback circuit, the output signal is blocked. In any case, the supply of the proportional operation component and the unit time integration component to the output signal is cut off. In the present application, “blocking” the supply of the proportional motion component or the unit time integral component means that the value of the proportional motion component or the unit time integral component is not supplied or is supplied as “0”. Yes.
Therefore, the output signal has a constant value because only the output signal before the unit time is fed back from the start to the end of the gain reduction change for the proportional operation.

The reactor water supply flow rate control device according to claim 3 is the reactor water supply flow rate control device according to claim 2, wherein the switch is upstream of the branch point or downstream of the junction. In place of the upstream side of the connection point with the feedback circuit, it is provided in a part of the proportional operation circuit from the branch point to the junction point, and the start and end of the gain reduction change for the proportional operation The supply of the proportional motion component to the output signal is cut off for a period of time up to.
The invention having the above-described configuration operates in the same manner as the invention described in claim 2, but by providing the switch in a part of the proportional operation circuit, an input signal is input to the integration operation circuit, and its unit time integration operation component Acts to be added to the output signal. Therefore, the output signal is the time from the start to the end of the gain reduction change for proportional operation, and only the proportional operation component is cut off from being supplied to the output signal. Since only the integral operation component is included, it gradually decreases.

According to a fourth aspect of the present invention, there is provided a reactor water supply flow rate control device , wherein the integration operation circuit in the reactor water supply flow rate control device according to the first aspect converts a component obtained by integrating the input signal into unit time for the unit time. a integrating operation circuit that generated by adding the ingredients is integral operation and before the reactor feedwater flow control device, the circuit of the input signal is branched at the branch point, the proportional to one branch side the operation circuit, the integration operation circuit in the other branch side, as well as connected in parallel, the signal adding by connecting in junction of the downstream side of the proportional operation circuit and said integration operation circuit, the proportional action the switch portion of the proportional operation circuit from said branch point through a NOT circuit a command signal decreasing change of the gain to the merging point provided for, the start and end of the reduced change of the gain for the proportional operation The time until The supply to the output signal of the example operation component is characterized in that blocked by the switch.
The invention with the above configuration operates in the same manner as the invention according to claim 1. Further, unlike the inventions according to claim 2 and claim 3, the integration operation circuit does not output the unit time integration operation component, but includes the integration operation component integrated up to the unit time before the unit time. Acts to output. Therefore, there is no need for a feedback circuit for feeding back the output signal of unit time ago. That is, a feedback function is added to the integration operation circuit itself. In such a configuration, a switch is provided in a part of the proportional operation circuit because only the proportional operation circuit needs to be blocked so as not to be added. The operations of the proportional operation circuit, the integration operation circuit, the negation circuit, and the switch are the same as those described in claims 2 and 3.

According to the reactor water supply flow rate control device of the first aspect of the present invention, the reactor water level control at the time of low output operation can be efficiently performed by controlling the opening of the water supply flow rate control valve by a slight change of the nuclear power control system. And can be performed stably. In addition, when the reactor water level rises during low power operation during a transient event, even if the reactor cleaning system dump valve is manually opened to change to the start-up mode, the reactor feedwater flow control Since the output signal of the equipment does not change significantly, it is possible to reduce the mental burden on the operator of the nuclear power plant, and it is also possible to prevent human error and improve the safety of plant operation. .
Furthermore, the above-mentioned effects can be exhibited by minor improvements such as the time from the start to the end of the gain reduction change for proportional operation, and the supply interruption of the proportional operation component and unit time integral operation component to the output signal. As a result, it is possible to lighten the burden of design change or refurbishment on the plant.

According to the reactor water supply flow rate control device of the second aspect, the same effect as that of the first aspect of the invention can be exhibited, and the unit time integral operation component is calculated by the integral operation circuit, so that the unit time By providing a feedback circuit to the previous output signal and feeding it back to the output signal, even if the component generated by the proportional operation circuit and the integral operation circuit is blocked from the output signal, the gain for proportional operation is reduced. Since the output signal of the unit time before the time from the start to the end of the change is fed back, the output signal can be output stably. This makes it possible to execute a gradual control that can reduce the mental burden on the operator.
Further, the supply of the component generated by the proportional operation circuit and the integration operation circuit to the output signal can be cut off by the switch.

  According to the reactor water supply flow control device of the third aspect, in addition to being able to exert the same effect as the invention of the second aspect, by providing a switch in a part of the proportional operation circuit, Only the proportional motion component can be cut off from being supplied to the output signal. Therefore, as in the invention described in claim 2, although the output signal does not become constant during the time from the start to the end of the gain reduction change for the proportional operation, the output signal gradually decreases, so that it is possible to perform moderately stable control. Is possible.

According to the reactor water supply flow rate control apparatus of the fourth aspect, the integral operation circuit does not output the unit time integral operation component but outputs the integral operation component up to the unit time. 3, there is no need to provide a feedback circuit for feeding back the output signal of a unit time ago.
Other effects are the same as those of the inventions described in claims 2 and 3.

It is a conceptual diagram for demonstrating the reactor water flow control apparatus which concerns on embodiment of this invention. 1 is a configuration diagram of a reactor water supply flow rate control apparatus according to Embodiment 1 of the present invention. It is a conceptual diagram which shows typically the input signal of the nuclear reactor water supply flow control apparatus in a prior art, a proportional operation | movement component, an integral operation component, and an output signal. It is a conceptual diagram which shows typically the input signal of the nuclear reactor water supply flow control apparatus in embodiment of this invention, a proportional action component, an integral action component, and an output signal. It is a block diagram of the reactor water supply flow control apparatus which concerns on Example 2 of this invention. It is a block diagram of the reactor water supply flow control apparatus which concerns on Example 3 of this invention. It is a conceptual diagram for demonstrating the water level control of the nuclear reactor of a boiling water nuclear power plant.

  A reactor water supply flow rate control apparatus according to an embodiment of the present invention will be described in detail with reference to Examples 1 to 3.

A reactor water supply flow rate control apparatus according to Embodiment 1 of the present invention will be described in detail with reference to FIGS. (In particular, corresponding to claims 1 and 2)
FIG. 1 is a conceptual diagram for explaining a reactor water supply flow rate control apparatus according to an embodiment of the present invention common to Examples 1 to 3. The same components as those described in FIG. 7 are denoted by the same reference numerals.
In FIG. 1, a difference between a water level signal 2 (subtraction) and a water level setting signal 3 (addition) is input as an input signal X to the reactor water supply flow rate control device 1 according to the embodiment of the present invention. The event targeted by the reactor water supply flow control device 1 according to the present invention is that the reactor 50 (see FIG. 7) is operating at a low output, and the reactor water level is controlled downstream of the reactor water pump 52. It is controlled by the water supply flow rate adjustment valve 4 on the side.
Therefore, the output signal Y from the reactor water supply flow rate control device 1 is output to the water supply flow rate adjustment valve 4.
In the present invention, the operator lowers the water level by opening the CUW dump valve 57 of the reactor purification system 51 (see FIG. 7) while the reactor water level is rising during such low power operation. However, in this case, the activation mode change logic circuit 6 operates, and the activation mode change signal 5 is output to the reactor water supply flow rate control device 1. The activation mode change signal 5 changes the operation mode of the nuclear power plant from the low power operation mode to the activation mode.
In order to change to this start-up mode, as shown in the start-up mode change logic circuit 6 in the figure, the feed water flow rate is low, the main steam flow rate is low, the reactor purification system (CUW) start permission, one or more electric feed water pumps The start mode change signal 5 output by inputting the operation state signal 7 such as operation, small feed water flow rate adjustment valve (LFCV) opening, automatic controller operation, etc. is required. Reference numeral 8 shown in the start mode change logic circuit 6 is a negation circuit, reference numerals 9a and 9b are AND circuits, and reference numeral 10 is an OR circuit.

Next, the operation of the reactor water supply flow rate control apparatus 1 according to the first embodiment of the present invention when the low-power operation mode is changed to the start-up mode will be described with reference to FIG. FIG. 2 is a configuration diagram of the reactor water supply flow rate control apparatus according to Example 1 of the embodiment of the present invention.
In FIG. 2, the reactor water supply flow rate control device 1 included in the reactor water supply control system 11 (see FIG. 7) has an activation mode change signal 5 output from an operation mode change unit 12 having an activation mode change logic circuit 6. Is received by the gain changing unit 13, and the gain changing unit 13 outputs a gain change request signal 19.
In the PI controller 14a provided in the reactor water supply flow rate control device 1, the input signal circuit 21 is branched into a proportional operation circuit 17 and an integration operation circuit 18 at a branch point 23, and is merged again at a junction point 24. Output signal circuit 25 is formed. The output signal circuit 25 includes a feedback circuit 28 that branches at the feedback branch point 27 and joins to the connection point 26. In the present application, the proportional operation circuit 17 and the integration operation circuit 18 are concepts including not only internal logic circuits but also lines (wiring) from the branch point 23 to the junction point 24.
Further, the PI control device 14a is provided with a switch 22 in the output signal circuit 25 from the junction point 24 to the connection point 26 of the proportional operation circuit 17 and the integration operation circuit 18, and the switch 22 has the above-described gain change request signal 19. The timer circuit 15 operates so as to be output for a certain time (Δt), and further, when the gain change request signal 19 is not present by the negation circuit 16, a signal is generated. Therefore, the low output operation mode is switched to the start mode. If it has not been changed, the switch 22 remains on, and the operation component calculated by the proportional operation circuit 17 and the integration operation circuit 18 in the input signal X is included in the output signal Y.

On the other hand, when the low-power operation mode is changed to the start-up mode, no signal is transmitted from the negation circuit 16, so that the switch 22 is released, and the input signal X is input to the proportional operation circuit 17 and the integration operation circuit 18. However, although it is calculated, it does not reach the connection point 26 as the output signal Y.
Operations in the proportional operation circuit 17 and the integral operation circuit 18 of the reactor water supply flow rate control apparatus 1 according to the first embodiment configured as described above will be described.
First, in the case of the low output operation mode, the proportional operation circuit 17 receives the gain signal 20 from the gain changing unit 13, and as shown in the equation (1), the difference between the product of the input signal X and the gain G, that is, The difference between the current value related to the product of the input signal X and the gain G and the previous value before unit time (one calculation cycle) is calculated to obtain an output signal Yp. That is, the proportional operation circuit is calculated between the input signal X as a change per unit time. Therefore, the output signal Yp that is repeatedly calculated every unit time is not always added at the junction 24, but is added only when a change occurs in the proportional operation calculation.

  Similarly, the integration operation circuit 18 receives the gain signal 20 and integrates the input signal X for unit time (one calculation cycle) as shown in the equation (2) to obtain an output signal Yi. In the equation (2), t represents a time variable. In equation (2), the integral calculation value of unit time is calculated by dividing the integral value by the integration time TI.

  Since the output signal circuit 25 includes the feedback circuit 28 from the feedback branch point 27 to the connection point 26 as described above, if the signal fed back by the feedback circuit 28 is a preceding signal F, the output signal Y is It is expressed by equation (3). The preceding signal F is the output signal Y before unit time (one calculation cycle), and the output signal Y has increments of Yp and Yi every unit time (one calculation cycle).

On the other hand, when the operation mode is changed from the low output operation mode to the start mode, the gain change request signal 19 is output by the timer circuit 15 for a certain time, for example, about 200 msec to 300 msec. The gain change request signal 19 is stopped by the negative circuit 16 and the switch 22 is released. Therefore, the input signal X is input to the proportional operation circuit 17 and the integration operation circuit 18 and the operation component is calculated, but is cut off by the switch 22, and finally the operation component by the proportional operation circuit 17 and the integration operation circuit 18 is calculated. Supply to the output signal Y is cut off.
That is, both Yp, which is the output signal of the proportional operation circuit 17, and Yi, which is the output signal of the integration operation circuit 18, become 0, and eventually only the feedback preceding signal F becomes Y = F.
In the first embodiment, the switch 22 is provided between the junction point 24 of the proportional operation circuit 17 and the integration operation circuit 18 and the connection point 26 of the output signal circuit 25 and the feedback circuit 28. However, the switch 22 is an input signal. It may be provided in the circuit 21. In this case, since the respective operation components are not calculated by the proportional operation circuit 17 and the integration operation circuit 18 with respect to the input signal X, the operation components supplied by the proportional operation circuit 17 and the integration operation circuit 18 to the output signal Y also in this case. There will be no. That is, both Yp and Yi may be regarded as 0, and eventually Y = F.
However, when the switch 22 is provided in the input signal circuit 21, the input signal X is cut off on the input side of the proportional operation circuit 17 and the integration operation circuit 18. Since the input signal X to the circuit 18 changes stepwise, Yp and Yi expressed by the equations (1) and (2) are also affected. In this case, this step input is a normal step. It is necessary to change the processing by recognizing whether the input is a change caused by mode switching.

Next, what effect the reactor water supply flow rate control apparatus 1 according to the first embodiment can exert will be described with reference to FIGS. 3 and 4 for comparison. FIG. 3 is a conceptual diagram schematically showing an input signal, a proportional operation component, an integration operation component, and an output signal of a reactor water supply flow rate control device in the prior art, and FIG. 4 is a reactor water supply flow rate in Embodiment 1 of the present invention. It is a conceptual diagram which shows typically the input signal of a control apparatus, a proportional action component, an integral action component, and an output signal.
3 and 4, the dotted lines shown in the vertical direction indicate the timing in time. Time t1 is the normal operation mode, time t2 is the mode change from the normal operation mode to the low-power operation mode, and time t3 is the low time. The mode change from the output operation mode to the start mode is shown.
In each of the four diagrams in FIGS. 3 and 4, reference numeral 40 denotes an input signal, reference numeral 41 denotes an integral value of a proportional action component calculated by the proportional action circuit 17, and reference numeral 42 denotes an integral action circuit 18. Integral operation components 43a and 43b indicate changes in the output signal with time. The input signal 40, the proportional motion component 41, and the integral motion component 42 are all the same, but the output signals 43a and 43b are different from those in the prior art.
Assuming that the water level is stable with respect to the water level setting in the normal operation mode, the input signal 40 changes at 0% without causing a difference between the signals. Even if the gain in the normal operation mode is “g0”, when the input signal 40 is 0, as understood from the equations (1) and (2), the proportional operation circuit 17 and the integration The proportional operation component 41 and the integration operation component 42 in the operation circuit 18 are also 0%, and the output signal 43a is also maintained at 0%.

  On the other hand, at time t2, the reactor enters a transient state for some reason due to a gain with respect to the operation state, and enters a low power operation mode. Further, if the reactor water level rises at that time, the water level setting becomes lower with respect to the water level, so the input signal 40 becomes “−a” (negative value). Assuming that the gain at the time of low output operation is “g1” in the proportional operation circuit 17 and “g2” in the integral operation circuit 18 (g2 = 1 / TI in equation (2), the same applies hereinafter), as shown in FIGS. From time t2 to time t3, the proportional motion component 41 is changed from 0% to "-a * (g1-g0)", and the integral motion component 42 is changed to "-a * g2 * t". Here, t is also a time variable. However, since the limiter works to avoid the output signal 43a from fluctuating too much, the output signal 43a becomes “−b” (where b <a * g1).

Furthermore, at time t3, the operation mode changes from the low output operation mode to the start mode. In the start-up mode, it is assumed that the gain further varies and becomes “g3” in the proportional operation circuit 17 and “g4” in the integral operation circuit 18. In this case, as shown in FIGS. 3 and 4, the proportional motion component 41 is “−a * (g3−g1)” (where g3 <g1), and the integral motion component 42 is “−a * g4 * t” (note that G4 <g3).
In this case, the integral motion component 42 is “−a” because the input signal 40 is unchanged, but the gain has decreased, so that it seems to have swung in the direction of raising the water level when considered based on the value at time t2. Looks like. In this case, since the limiter does not work, in the case of the conventional technique, the output signal 43a becomes “c1” (positive value, c1 = −b + a * (g1−g3)), and the output is intended to raise the water level. A signal 43a is generated. Note that a, b, c, g0 to g4 are all constants, and c1> b in this embodiment. Since the limiter value is changed to a value lower than “−b” when the operation mode changes from the low output operation mode to the start mode, the output signal 43a that decreases from “c1” In some cases, the time limit value “−b” may be exceeded.

On the other hand, as described with reference to FIG. 2, the output signal 43 b of the first embodiment is such that the switch 22 is cut off during Δt, so that the input signal 40 is sent to the proportional operation circuit 17 and the integration operation circuit 18. Even if the operation component is supplied and the operation component is calculated, the supply of the operation component to the output signal 43b by the proportional operation circuit 17 and the integration operation circuit 18 disappears by the connection point 26, and the supply to the output signal 43b is cut off. (Supply becomes 0). Only the preceding component F becomes the component of the output signal 43b after all, and the component from time t2 to time t3 is followed as indicated by the symbol A in the circle drawn by the dotted line in FIG. Become. That is, “−b” is maintained.
After Δt from time t3, the gain change request signal 19 is stopped and does not exist. Therefore, the negation circuit 16 negates the signal to generate a signal, the switch 22 is maintained in the on state, and the input signal X is maintained. The proportional motion component 41 and the integral motion component 42 calculated by the proportional motion circuit 17 and the integral motion circuit 18 are included in the output signal 43b again.
At that time, the change in gain is completed in the proportional motion component 41, and the gain of the start mode is obtained before and after the calculation of the unit time, so there is no change given to the output signal 43b as the value of the proportional motion component 41. (That is, Yp = 0), the gentle change obtained by the integral operation component 42 is output as the output signal 43b together with the preceding signal F (-b in the figure). That is, the output signal 43b is “c2” (c2 = −b−a * g4 * t).
In FIG. 4, the limiter value in the startup mode is changed to be lower than “−b”, so that “c2” in the startup mode can be decreased beyond “−b”. .

As described above, in the first embodiment, when the gain when the operation mode is changed from the low-power operation mode to the start-up mode is changed, the change from the start to the end of the gain reduction change for the proportional operation is completed. The output signals Yp and Yi from the proportional operation circuit 17 and the integration operation circuit 18 are cut off by using the switch 22 provided on the output signal circuit 25 between the junction point 24 and the connection point 26 to the output signal Y. As a result, only the preceding signal F is used as a component of the output signal Y by using the feedback circuit 28, and the output signal Y can be prevented from suddenly becoming a positive value and a large value. it can. It is possible to maintain an output signal that gradually decreases after the time Δt.
Therefore, even if the reactor water level rises during a low power operation during a transient event in a nuclear power plant, even if the reactor cleaning system dump valve is manually opened to change the startup mode, It is possible to prevent a control state that raises the water level. As a result, no mental burden is placed on the operator, and there is little possibility of causing a human error from a mental margin, so that the operation of the nuclear reactor can be maintained. In addition, it is possible to maintain an appropriate reactor water level with respect to the structure in the reactor even during low power operation during transition, and thus has an excellent effect that safer plant operation is possible. Yes.

Next, a reactor water supply flow rate control apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. (In particular, corresponding to claims 1 and 3)
FIG. 5 is a configuration diagram of a reactor water supply flow rate control apparatus according to Embodiment 2 of the present invention. In FIG. 5, the same components as those in FIG. .
5, in the reactor water supply flow control device 1 according to the second embodiment, the switch 22 provided in the output signal circuit 25 in the first embodiment is connected to the junction 24 on the downstream line of the logic circuit of the proportional operation circuit 17. The other configurations are the same as those in the first embodiment.
In the second embodiment configured as described above, similarly to the first embodiment, the gain change request signal 19 output from the gain changing unit 13 when the operation mode is changed from the low output operation mode to the start mode is the negative circuit 16. Therefore, the switch 22 is released because no signal is transmitted from the negation circuit 16, and the input signal X is input to the proportional operation circuit 17 and the integration operation circuit 18 and is calculated, but the output of the proportional operation circuit 17. The signal Yp is cut off and not added at the junction 24, and only the output signal Yi of the integration circuit 18 is added to the preceding signal F at the connection point 26 and output as the output signal Y.
In the second embodiment, the switch 22 is provided at the position to the junction point 24 on the downstream side of the logic circuit. However, the same effect can be obtained by providing the switch 22 at the position of the branch point 23 on the upstream side of the logic circuit. can get.
In the second embodiment, the input signal 40, the proportional motion component 41, and the integral motion component 42 shown in FIG. 4 are the same, but in the first embodiment, the output signal 43b at time t3 is “−b”. On the other hand, in the second embodiment, the integral operation component 42 is not blocked and is added to the preceding signal F, so that “−b−a * g4 * t” is obtained, and the gentle slope is Δt compared to the first embodiment. However, it can be easily understood that the excellent effect of the first embodiment is exhibited also in the second embodiment. Even in this case, the limiter value in the startup mode is changed to be lower than “−b”, so that “c2” in the startup mode can be decreased beyond “−b”.

Finally, a reactor water supply flow rate control apparatus according to Embodiment 3 of the present invention will be described with reference to FIG. (In particular, corresponding to claims 1 and 4)
6 is a block diagram of a reactor water supply flow rate control apparatus according to Embodiment 3 of the present invention. In FIG. 6, the same components as those in FIG. .
In FIG. 6, in the reactor water supply flow rate control device 1 according to the third embodiment, the feedback circuit 28 branched from the feedback branch point 27 in the second embodiment is deleted, and other configurations are implemented. Similar to Example 2.
In the third embodiment, instead of providing the feedback circuit 28, the integrating operation circuit 18 is provided with a feedback function. That is, as the output signal Yi of the integration operation circuit 18, the integral value in the unit time (one calculation cycle) is added as it is to the previous calculation as the preceding signal F as shown in the equation (4). However, FYi in the equation (4) is different in that F in the equation (3) is a preceding signal of the output signal Yi of the integrating operation circuit 18 while F is a preceding signal of the output signal Y. In this case, the output signal Y can be expressed as Equation (5).

In the third embodiment configured as described above, the switch 22 is provided in a part of the circuit of the proportional operation circuit 17 as in the second embodiment, so that the signal cut off by the switch 22 is an output signal from the proportional operation circuit 17. Since it is Yp, the output signal Y becomes Yi including the preceding signal FYi. In this case, the preceding signal FYi included in the output signal Yi of the integrating operation circuit 18 has a definition different from that of the preceding signal F in the equation (3), but the output signal Yp of the proportional operation circuit 17 that changes in a step shape is cut off. Therefore, it can be considered as substantially equivalent.
That is, the diagram of the output signal 43b in FIG. 4 in the third embodiment can be expressed in the same manner as in the second embodiment. Therefore, the third embodiment can exhibit the same effect as the second embodiment.
In addition, in this application, although Example 1-3 demonstrated the case where the difference of the water level setting signal of a nuclear reactor and a water level signal was a negative value (water level setting signal <water level signal), conversely, Even when the difference between the water level signals is a positive value (water level setting signal> water level signal), the same can be implemented.

  As described above, the present invention can be used in the field of the reactor water supply flow rate control device of the reactor water supply control system of the boiling water nuclear power plant.

  DESCRIPTION OF SYMBOLS 1 ... Reactor feed water flow controller 2 ... Water level signal 3 ... Water level setting signal 4 ... Feed water flow rate control valve 5 ... Start mode change signal 6 ... Start mode change logic circuit 7 ... Operation state signal 8 ... Negative circuit 9a, 9b ... Logic Product circuit 10 ... Logical sum circuit 11 ... Reactor water supply control system 12 ... Operation mode change unit 13 ... Gain change unit 14a, ~ 14c ... PI controller 15 ... Timer circuit 16 ... Negative circuit 17 ... Proportional operation circuit 18 ... Integration operation Circuit 19 ... Gain change request signal 20 ... Gain signal 21 ... Input signal circuit 22 ... Switch 23 ... Branch point 24 ... Junction point 25 ... Output signal circuit 26 ... Connection point 27 ... Feedback branch point 28 ... Feedback circuit 40 ... Input signal 41 ... Proportional operation component 42 ... Integral operation component 43a, 43b ... Output signal 50 ... Reactor 51 ... Reactor cleaning System 52 ... feed water pump 53 ... feed water pipe 54 ... feed water flow meter 55 ... main steam flow meter 56 ... main steam pipe 57 ... CUW dump valve

Claims (4)

The difference between the water level setting signal and the water level signal of the reactor of the boiling water nuclear power plant is used as an input signal, and a proportional operation circuit for generating a component in which the input signal is proportionally operated, and the input signal is integrated for unit time . An integration operation circuit that generates a component, and generates an output signal by adding the component that has been proportionally operated with the input signal and the component that has been integral-integrated for the unit time. A reactor water supply flow control device for controlling the opening of a flow control valve,
A switch that cuts off the supply of at least the component of the proportional operation and the integral operation to the output signal when the gain for the proportional operation is decreased and changed by changing the operation mode of the reactor; And a switch for cutting off the time from the start to the end of the gain reduction change for the proportional operation. The reactor feedwater flow control device, the circuit of the input signal is branched at the branch point, the proportional action circuit in one branch side, the integration operation circuit in the other branch side, as well as connected in parallel The proportional operation circuit and the integration operation circuit are connected at a downstream junction to add a signal, and a feedback circuit that feeds back the output signal is connected to the downstream side to add the output signal before the unit time. And a command signal for changing the gain for the proportional operation via a negation circuit upstream of the branch point or downstream of the junction and upstream of the connection point with the feedback circuit. wherein the provided switch, said switch supplying the result to proportional time from the start to the end of reducing change of the gain for operation, the output signal of the proportional action component and the unit time integral action component Accordingly reactor feedwater flow control device according to claim 1, wherein the blocking.   The switch is located on the upstream side of the branch point or on the downstream side of the junction point and on the upstream side of the connection point with the feedback circuit, instead of the proportional operation circuit from the branch point to the junction point. 3. The nuclear reactor according to claim 2, wherein the reactor is provided in part to cut off the supply of the proportional motion component to the output signal for a time from the start to the end of the gain reduction change for the proportional motion. Feed water flow control device. The reactor feedwater flow rate control device is an integration operation circuit in which the integration operation circuit generates a component obtained by integrating the input signal for unit time integration with a component for integration operation performed before the unit time. there, the circuit of the input signal is branched at the branch point, the proportional action circuit in one branch side, the integration operation circuit in the other branch side, as well as connected in parallel, and the proportional operation circuit The proportional operation circuit from the branching point to the merging point is connected via a negation circuit with a command signal for changing the gain for the proportional operation by adding a signal by connecting at a merging point on the downstream side of the integrating circuit. the part provided with the switch, the time from the start to the end of the reduction changes the gain for the proportional action, claims, characterized in that interrupting the supply to the output signal of the proportional operation component by the switch Item 1 Reactor feedwater flow control device.