JPH01263403A - Supply water controlling device - Google Patents

Abstract

PURPOSE:To enable a water level controlling approximating to a normal operation of a water level controlling device to be performed by a method wherein each of variation of a main steam flow rate signal and variation of water feeding flow rate and each of a variation of a pressure signal of a reactor or a boiler and a water level signal are relatively offset in a transition state. CONSTITUTION:In case that a low transition state is continuously generated, at first a variation of a main steam flow rate signal S8 is detected by a transition accommodator 14, a transition main steam flow rate signal S23 is outputted in advance by a reactor pressure compensation circuit, thereby a water feeding flow rate S13 is corrected. As a water feeding flow rate S13 is controlled, a water feeding flow rate signal S7 is also varied. If this amount of variation is coincided with an amount of variation of the main steam flow rate, it is eliminated and a biasing for an output of a water level controlling device 2 becomes zero. Similarly, after the main steam flow rate signal S8 is varied, void is increased or decreased in response to a variation of inter-reactor pressure generated in delay, thereby a water level in the reactor is rapidly increased or decreased. A rapid variation of this water level signal S1 is detected by a transition accommodator 11, a transition water level signal S21 is added to an output part as a biasing signal and this is compensated by an output signal of the transition output signal S6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a water supply control device that controls the flow rate of water supply so as to maintain the water level of a nuclear reactor or boiler at a certain set value.

(Prior Art) In a boiling water nuclear reactor (hereinafter abbreviated as BINR) or a drum boiler, it is necessary to maintain the reactor water level or boiler water level at a certain level from the standpoint of reactor or boiler performance or safety. For this reason, the water supply flow rate is controlled by a water supply control system according to fluctuations in the reactor water level or boiler water level. Figure 4 shows the conventionally used water supply flow rate control device (
An example in which the method (see Japanese Patent Application No. 60-279048) is applied to reactor water supply control will be shown.

In FIG. 4, a water level deviation signal S3 obtained by inputting a reactor water level S detected by a water level detector and a preset water level S2 to an adder 1 is input to a water level controller 2.

The water level controller 2 is composed of a proportional controller and an integral controller, and outputs a control signal S4 in accordance with reactor water level fluctuations that occur during normal operation of the reactor, for example, due to a change in reactor output.

In addition, regarding reactor water level fluctuations caused by a rise in reactor pressure, where the proportional and integral equations described above are a problem, the reactor pressure signal S5 is manually generated and set to respond to transient pressure changes. The transient compensator 3 outputs a transient pressure signal S6 that suppresses reactor water level fluctuations.

Furthermore, if the feed water flow rate and the main steam flow rate are equal, the water level fluctuation will be zero, so the feed water flow rate signal S7 and the main steam flow rate signal S8
input to the adder 4 so that the flow rate deviation signal S9 of is also set to zero,
The difference signal S9 between the two is multiplied by a gain of 5.

Each output signal S of the water level controller 2, transient compensator 3, and cane 5
,,,S6. S□. is inputted into the adder 6, and the flow rate control signal Sll, which is the sum of these output signals, is inputted into the water supply controller 7 to calculate the water supply flow rate, and an activation signal S to the water supply servo system 8 is inputted.
Outputs 12. Thereby, the water supply flow rate S13 corresponding to the flow rate control signal 81.1 can be obtained.

By the way, the main factors that cause fluctuations in reactor water level are changes in reactor pressure, feed water flow rate, and main steam flow rate due to changes in reactor power.

As mentioned above, the main steam flow rate 80 and the feed water flow rate S7 are usually equal, so if a mismatch occurs between the two, the deviation signal (mismatch signal) S! The water supply flow rate 513 is controlled by multiplying l by a gain so that the flow rate deviation S9 becomes zero. The main steam flow rate and the feed water flow rate are naturally mismatched in transient states such as load shedding, recirculation pump lip, water pump 1 lip, etc., so the feed water flow rate is determined according to the amount and sign of the mismatch. Coordination is improved by increasing or decreasing the number of commands.

(Problem to be Solved by the Invention) However, the deviation signal S9 becomes a disturbance when received by the water level controller 2, leading to an increase in the amount of overshoot and the settling time. For example, as shown in FIG. 5, when the MG speed is rapidly increased, the main steam flow rate S.

After the reactor water level S1 rapidly decreases, the transient compensator 3 detects a decrease in the reactor pressure signal S5, and a correction is made to reduce the feedwater flow rate S],3, but the main steam flow rate signal Sn and the feedwater flow rate Since a large feed water increase bias is applied due to the deviation of the signal S7, the recovery of the reactor water level S1 is slow, and in the latter half, there is a tendency to overshoot because the feed water flow rate Se] is extra controlled.

Therefore, it is necessary to make adjustments to increase the gain 5 shown in FIG. 4 to improve the response characteristics in the transient state, but the gain! l
! + There is a limit to just adjusting. Also, Atomic Kaburan! The proportion of power generated by - in the electric power system is increasing year by year, so it is becoming necessary for Atomic Power Plants 1 to 1. In these operations, transient states occur continuously in the plant, and there is a risk that the above-mentioned transient state will occur at this time.

In this case, the prior art deals with changes in reactor pressure or boiler internal pressure, feed water flow rate, and main steam flow rate due to changes in reactor or boiler output, which are the main factors that cause fluctuations in reactor water level or boiler water level during operation of a nuclear reactor or boiler. Regarding pressure fluctuations, by applying the reactor or boiler pressure signal to the water level controller via a transient compensator with differential characteristics, transient fluctuations in the reactor water level or boiler water level caused by fluctuations in reactor pressure or boiler internal pressure can be detected. -4
= , and for the feed water flow rate and main steam flow rate, the detected flow rate was used as a feedback signal, responding quickly to changes in these physical quantities and suppressing large fluctuations in the reactor water level or boiler water level.

However, due to changes in plant operation, the number of AFC operations and output fluctuations increases, the main steam flow rate and feed water flow rate fluctuate more, and small transient conditions occur continuously, the feedback of the physical quantities has a large gain and becomes large. Although fluctuations are suppressed, the influence of disturbance on water level controllers can no longer be ignored.

In addition, water level fluctuations due to swelling of the reactor water level or boiler water level due to recirculation pump tripping or fluctuations in the pressure control system will return to the original water level as the recirculation flow rate and pressure within the reactor or boiler settle. , the conventional water supply control system shown in Figure 4 inputs the water level deviation signal directly into the control system, so it appears to follow the above water level fluctuations and adjust the water supply flow rate, which causes unnecessary water level fluctuations. However, at the end of the transient phenomenon, an excess or shortage of water caused the water supply equipment to trip, making further control impossible.

Therefore, the present invention provides an economical water supply control device that can quickly suppress large water level fluctuations that occur during operation of a nuclear reactor or boiler and operate the reactor or boiler stably. The purpose is to

[Configuration of the Invention (Means for Solving the Problems) The present invention detects the water level of the reactor or boiler and eliminates the deviation between the actual water level and the set water level in order to control the water level of the reactor or boiler. In a water supply control device that controls the water supply flow rate using a water level controller, the pressure of the reactor or boiler, the main steam flow rate generated from the reactor or boiler,
Each detection signal of the water supply flow rate supplied to the nuclear reactor or boiler and the reactor water level or boiler water level is added to the output signal of the water level controller via a transient compensator with differential characteristics.

(Function) With the above means, in a transient state, fluctuations in the main steam flow rate signal and fluctuations in the feed water flow rate signal, as well as fluctuations in the reactor or boiler pressure signal and fluctuations in the water level signal, cancel each other out, and the water level Since the bias applied to the output signal of the controller becomes zero, water level control close to steady operation is possible.

(Example) Hereinafter, an example in which the present invention is applied to an atomic couplant will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a configuration diagram of a water supply control device according to an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 4 indicate the same or corresponding parts, and the points that differ from the configuration in FIG. , the reactor water level signal Sl is input to the transient compensator 11 with differential characteristics, and the obtained transient water level signal 521 is added to the adder]2, and the feed water flow rate signal Sl is input to the transient compensator 13 with differential characteristics. The transient feedwater flow rate signal S22 and the main steam flow rate signal SO
is inputted into the transient compensator 14 with differential characteristics, and the transient main steam flow rate signal S23 obtained is inputted into the adder 15, and the obtained deviation signal S24 is added to the adder]2, and the deviation signal S2
4 and the transient water level signal SZX is added to the adder 6.

With this configuration, the reactor water level is controlled by the water level controller 2, which is composed of a proportional and integral controller I, so that the water level deviation signal S3 between the set water level signal S2 and the reactor water level signal S1 is made zero. . On the other hand, during normal operation, the feedwater flow rate signal S7 and the main steam flow rate signal So gradually and similarly change according to a predetermined output rate. Therefore, fluctuations in the reactor water level that occur during normal operation, for example due to changes in reactor output, hardly occur.

Further, the reactor water level fluctuation caused by the rise in reactor pressure, which poses a problem in the response of the proportional and integral controllers, can be explained in exactly the same way as the operation of the conventional circuit shown in FIG. That is, when the generator frequency rises above a certain value due to a disturbance occurring in the power system, the governor operates to close the control valve that regulates the steam flowing into the turbine. At this time, the reactor pressure increases and the void 1-, which is always present in the reactor while the reactor is in operation, collapses, and the reactor water level drops rapidly due to the disappearance of the void. The water level controller 2 described above is a proportional/integral controller I/roller, so the response to sudden changes in the reactor water level is slow, so the transient compensator 3 detects sudden pressure changes in the reactor, A transient pressure signal S6 corresponding to a change in the signal S5 is added to the output S4 of the water level controller 2 to suppress reactor water level fluctuations caused by reactor pressure.

As shown in FIG. 2, this transient compensator 3 is composed of an incomplete differentiator circuit 3A, a phase compensation function 3B, and a limiter 3C. The incomplete differential circuit 3A does not respond to long-term reactor pressure fluctuations (several tens of seconds or more) that occur during operation, but generates an output in response only to pressure fluctuations that cause rapid water level fluctuations in the reactor. Moreover, the phase compensation function 3B is
It is determined to match the frequency range in which phase compensation is to be performed.

- As an example; gain, TJ~5; time constant,
S: Laplace Hikanko. The output S6 of the transient compensator 3 acts as a bias for the reactor water level control system and does not directly affect the stability of the reactor water level control system. Therefore, the time constant T]~5 is determined to compensate for the control delay from the transient pressure signal S6 in FIG. 1 to the reactor water level through the water supply controller 7. Further, the gain is determined so that the response of the water supply control system to reactor pressure fluctuations is satisfactory. Further, a limiter is provided to limit the output so that the transient compensator output Sb becomes excessive and the reactor water level does not fluctuate significantly.

However, with the above measures alone, furnace pressure fluctuations with relatively gentle changes occur continuously, such as when output fluctuations are made to tune to the grid frequency during AFC operation, or when output changes are made for power adjustment. This may cause problems in some cases. The reactor pressure changes with a time delay as a result of changes in the main steam flow rate, so if an attempt is made to control the feed water flow rate S13 to keep the reactor water level constant due to this pressure change, the small transient state will occur periodically. If this occurs, when the main steam flow rate signal So increases, the feed water flow rate S13 is increased by the corrected transient pressure signal s6 from the transient compensator 3. If there is a phase shift such that the main steam flow rate flowing into the turbine is decreased due to governor operation when the feed water flow rate signal s7 is detected to have increased, then in the conventional circuit shown in Fig. 4, the main steam flow rate signal The deviation between S8 and the water supply flow rate signal s7 becomes large and is multiplied by a gain of 5, so that a very large flow rate control signal Sll is applied to the water supply controller 7 for a long time to control the water supply flow rate, resulting in extra water level fluctuations. It turns out.

Therefore, in the control device of the present invention, the transient compensators 11.13.14 having the same configuration as shown in FIG.
The main steam flow rate signal So and the reactor water level signal sl are provided respectively, and the output signals of these transient compensators 11, 13, and 14 are added to the output side of the water level controller 2. Since the transient compensator output s[i acts as a bias for the reactor water level control system, it does not follow gradual changes in each process signal during normal operation, so it has no direct effect on the stability of the reactor water level control system. No impact.

On the other hand, when the small transient state occurs continuously, a change in the main steam flow rate signal Se is first detected by the transient compensator 14, and a transient main steam flow rate signal S23 is outputted before the furnace pressure compensation circuit. As a result, the supply=11=water flow rate S13 is corrected. When the feed water flow rate S13 is controlled, the feed water flow rate signal S7 also changes, and when this amount of change matches the amount of change in the main steam flow rate, it is canceled out, and the bias to the output of the water level controller 2 becomes zero. Similarly, after the main steam flow rate signal So fluctuates, voids increase or decrease due to a change in the reactor pressure that occurs with a delay, and the reactor water level rapidly increases or decreases. This sudden change in the water level signal S1 is detected by the transient compensator 11, and the transient water level signal S2 is applied as a bias to the output side of the water level controller 2 to cancel out the output signal of the transient pressure signal S6.

As mentioned above, in the transient state, the main steam flow rate signal So
The fluctuations in the feed water flow rate signal S7, as well as the fluctuations in the reactor pressure signal S5 and the fluctuations in the reactor water level signal S1, cancel each other out and act so that the bias becomes zero, so that the water level is close to that of steady operation. Control becomes possible. Therefore, the transient compensator I3 is determined to compensate for the control delay from the transient feedwater flow rate signal S22 to the reactor water level through the feedwater controller 7, and the gain has the same responsiveness to main steam flow rate fluctuations. It is determined that Similarly, transient compensator 14
is the feedwater flow rate from the transient main steam flow rate signal S23 through the feedwater controller 7, and is determined to compensate for the control delay until the reactor water level is finally reached, and the gain is determined to be equivalent to feedwater flow rate fluctuations. be done. In addition, the transient compensator 11
compensates for the control delay from the transient water level signal 323 to the reactor water level through the water supply controller 7, and the gain is determined to be equivalent to that of the reactor pressure compensation system. For example, as shown in FIG. 3, if we consider the case where the MG speed is suddenly increased as in the conventional example shown in FIG. The signal S23 is output, and in order to correct the feed water flow rate S13 in the increasing direction, the transient compensator 13 detects that the reactor water level S1 has started to recover and the feed water flow rate signal S7 has changed in the increasing direction, and the transient feed water flow rate signal S22 is Output. As a result, an increase in the feed water flow rate S13 is suppressed, and recovery of the reactor water level is temporarily suppressed.

Thereafter, the transient pressure signal S6 caused by the decrease in the reactor pressure signal S5 operates to reduce the water supply, but at the same time, the transient compensator 11 detects a decrease in the reactor water level S and operates to increase the water supply flow rate S13. do. Therefore, it can be seen that the bias for increasing the water supply and the bias for the water supply area are applied in a well-balanced manner, and the latter half overshoe 1 to force 1 water level S1 is quickly set as shown in FIG.

In the above embodiment, the water supply control device of the present invention is applied to an atomic power plant, but it can be similarly applied to a thermal power plant. In this case, in the case of a nuclear reactor, the change in the recirculation flow rate is expressed by the change in output due to the circulation of the boiler, that is, the change in the main steam flow rate, whereas in the case of a nuclear reactor, the change in the water level due to the water link is expressed by the change in the main steam flow rate. In this case, there are differences mainly expressed as water level Yumeshima and 2, but according to the configuration of the present invention, transient compensation is performed for both the 7.F level fluctuation and the main steam flow rate fluctuation, so it can be explained in the same way.

[Effects of the Invention] As described above, according to the water supply control device of the present invention, large water level fluctuations that occur during operation of a nuclear reactor or boiler, and small transient states that occur continuously, can be controlled by the main water level fluctuations. The main steam flow rate fluctuation, feed water flow rate fluctuation, and pressure fluctuation, which are the main causes, can be quickly suppressed.

Therefore, an operating margin in these transient states is ensured, and stable operation of the nuclear reactor or thermal power blast 1- can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a water supply control device showing an embodiment of the present invention, and FIG. 2 is a block diagram of the transient compensator shown in FIG. 1. FIG. 3 is a response characteristic diagram of the water supply control device shown in FIG. 1, FIG. 4 is a block diagram of a conventional water supply control device, and FIG. 5 is a response characteristic diagram of the conventional water supply control device. 1.4, 6, 12.15... Adder, 2... Water level controller, 3, ] ], . ]3.14...Transient compensator, 5...Gain, 7.Self-supply water controller, 8...Water supply servo system.

Claims (1)

[Claims] In order to control the water level of a nuclear reactor or boiler, a water supply control device detects the water level of the reactor or boiler and controls the water supply flow rate using a water level controller so that the deviation between the actual water level and the set water level is zero. A circuit that detects changes in the pressure of the reactor or boiler, a circuit that detects changes in the flow rate of feed water supplied to the reactor or boiler, and a circuit that detects changes in the flow rate of main steam generated from the reactor or boiler. and a circuit for detecting a change in the water level of a nuclear reactor or boiler, and the output of the change detection circuit is added to the output of the water level controller to control the water supply flow rate.