JPS60202391A - Automatic frequency control operation condition predicting device - 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 [Technical Field of the Invention] The present invention relates to an automatic frequency control operating condition prediction device that predicts and outputs data necessary for controlling operating conditions of a nuclear reactor in a nuclear power plant.

[Technical background of the invention]

As the proportion of nuclear power plants in the power system increases, nuclear power generation is not only operated for base load as in the past, but also for output power such as load following operation and automatic frequency control operation (hereinafter referred to as AFC operation). It has become increasingly necessary to perform adjustment operations. An explanation will be given below using a boiling water nuclear power plant (hereinafter referred to as BWR) as an example.

In AFC operation, when the grid frequency of the power grid deviates from the standard value, an AFC request signal is sent from the central power dispatch center to each plant, and based on this, the generator output is increased or decreased with the plants (this is done twice, and the grid frequency is changed). Generally, in a BW reactor, the control method C2 for the reactor thermal output is a reactivation method in which the core void ratio is changed by increasing or decreasing the core flow rate, and the reactivity is adjusted by controlling the moderator density. There are two methods: a circulation flow rate control method and a control rod operation method that adjusts the reactivity by changing the amount of control rods, which are neutron absorbers, inserted into the reactor core.

However, since AFC operation involves a very large number of operations and is performed under high output conditions, it is not appropriate to adjust the thermal output using a control rod operation method that imposes a large mechanical and thermal load.
Since the amount of change in core thermal power is small, it is common to achieve this using the recirculation flow rate control method alone.

On the other hand, as a result of nuclear fission in the reactor core, iodine-135 and its daughter nucleus xenon-135 (hereinafter simply referred to as xenon) are produced, but this xenon has a particularly large thermal neutron absorption cross section among the fission products. Since its concentration is large, it has a considerable influence on the reactivity of the reactor core, although the time constant is large. The xenon concentration also changes spatially and temporally when the core thermal output fluctuates, and becomes a factor that changes the subsequent thermal output and its distribution. Therefore, in order to achieve a predetermined output state during power change operation, it is necessary not only to adjust the core flow rate but also to compensate for changes in reactivity due to changes in the xenon concentration distribution through control rod operations if necessary. .

Figure 1 shows the temporal changes in the core thermal output, core flow rate, xenon concentration, and iodine concentration when load following operation is performed only by adjusting the core flow rate. Curve a in the figure
curve C represents the core thermal output, curve C represents the core flow rate, curve C represents the xenon concentration, and curve mci represents the iodine concentration. From this figure, we can see that the core thermal output increases or decreases according to the increase or decrease in the core flow rate, but after changing the output (2) In order to maintain a constant output, the core flow rate must also be increased or decreased in response to the increase or decrease in the xenon concentration, and the reactivity can be reduced. I understand that you are being compensated.

At this time, the core thermal output distribution also changes temporally and spatially as the xenon concentration distribution changes and the core flow rate changes.

On the other hand, in BW reactors, various restrictions are imposed on operating conditions in order to maintain the integrity of the nuclear fuel and equipment inside the reactor. Limits are established for each state quantity, and include those related to neutron flux, core thermal power, core flow rate, reactor water level, recirculation pump speed, and pump cavitation.

FIG. 2 illustrates various limiting conditions that are particularly imposed between core thermal output and core flow rate among these limitations. In the figure, the horizontal axis represents the core flow rate, and the vertical axis represents the core thermal output, and the area indicated by 1=hatching in the figure is the operation permissible area. Furthermore, in order to maintain the open and direct integrity of the fuel, cladding, and g, an operating method that allows changes in the power distribution only within the core thermal power distribution (hereinafter referred to as the PC envelope) when the fuel is run-in, and Restrictions and the like are set in consideration of an index (hereinafter referred to as MCP) that determines the margin for water, which is a coolant, to reach a boiling transition.

Each of these limits is conservatively set with a considerable safety margin expected, but when performing two AFC operations in a nuclear power plant, the operation must be performed within the range of each limit.

In order to suppress fluctuations in each parameter of the plant within each operating limit, limits are placed on the AFC signal input from the central power dispatch center, and limits on the width of the AFC signal (hereinafter referred to as AFC allowable width) are set appropriately. This is achieved by

Since the AJ″C allowable width generally depends on the base output of the plant, in order to perform AFC operation optimally, the AFC
The allowable width and base output must be set appropriately. The AFC operation plan is whether this setting is planned in advance before starting AFC operation.

[Problems with background technology]

Conventional nuclear power plants are operated at rated output for base load with emphasis on economic efficiency, and output change operations such as AFC operation are not performed. Therefore, there is no device that specifically plans AFC operation under the many limiting conditions mentioned above, and it is essential to create an AFC operation plan, especially when xenon is in a transient state and the core condition fluctuates over a long period of time. A device that has the function of predicting the core state and predicting AFC operating conditions based on it has not yet been realized.

[Purpose of the invention]

This invention was made to deal with the above-mentioned circumstances, and its purpose is to prevent the nuclear power plant from being operated in excess of each operating limit and damaging the integrity of the plant when performing AFC operation. AFC most suitable for
An object of the present invention is to provide an AFC operating condition prediction device indispensable for realizing operation plan creation.

[Summary of the invention]

In order to achieve the above object, the present invention provides an automatic frequency control operating condition prediction device that predicts and outputs an output pattern necessary for automatic frequency control operation based on each parameter indicating the core state of a nuclear reactor. An operator input device that receives a width request pattern signal and a base output request pattern signal, and a dynamic characteristic analysis code that predicts core state quantities based on the history signals of each of the parameters in response to the AFC allowable width request pattern signal. A base power prediction device that starts up, calculates the margin of the parameters, and predicts and outputs the transition of the maximum base power within a range that does not deviate from the allowable operating range of the reactor, and the base power In response to the request pattern signal, the dynamic characteristic analysis code is started to calculate the margin of each of the parameters, and based on this, the transition of the maximum AFC allowable width within the range that does not deviate from each of the allowable operating ranges of the reactor is calculated. an AFC permissible width prediction device that predicts and outputs the AFC permissible width request pattern signal;
The present invention is characterized in that it is provided with a determination device that transmits the prediction signal to the FC allowable width prediction device and outputs the prediction signal output from both of the prediction devices as a time function.

[Embodiments of the invention]

Hereinafter, this invention will be explained in detail based on examples.

Figure 3 is a control system block diagram showing an example of a reactor power adjustment operation method using a recirculation flow rate control method in a BW reactor.
Output control device 1, negative city setting device 2, recirculation flow rate controller 3,
Speed controller 4, MG upper set, nuclear reactor 6, turbine 7,
It is composed of an AFC allowable width setting device 11 and the like.

The output control device 1 includes an output pattern generator 8,
When the load target pattern A is set in advance, the output pattern generator 8 outputs an output request signal C according to the load target pattern at each time.

In addition, the output control device 1 includes an AFC controller 9 and an AFC controller 9.
A permissible width limiter 10 is provided, and after the AFC request signal fl from the central power dispatch center is phase compensated via the AFc controller 9, the AFC permissible width controller 10 limits the width of signals exceeding a specific size. It is output as an Ai;'C request signal. The AFC allowable width setting device 11 monitors the plant old and core state quantities and sets the limits of the AFC and allowable width limiter 10 in order to impose appropriate limits on the width of the AFC signal so that these are within the operational allowable range. This is the device to be configured.

The S-C output request signal C and the AFC request signal are added at the output of the output control device 1 and output as the load request signal E. Furthermore, the deviation from the plant's electrical output N is taken and a load deviation signal is obtained. F and the load setting device 2C is operated by two people. The load setter output G is input to the recirculation flow rate controller 3,
The speed request H, which is the output thereof, is subjected to the deviation from the MG set generator speed J, and is inputted to the speed control unit 114I as a speed error request signal (2). The speed controller 4 controls the power generation rate of the MG set 50, and controls the recirculation pump speed thereof to manipulate the reactor recirculation flow rate (core flow).

Inside the reactor 6, recirculation flow control (two-way main steam flow,
7hl is adjusted according to increases and decreases in reactor thermal output. Then, the drowsiness output N generated in the turbine 7 is manipulated by increasing or decreasing the main steam flow rate M, and by feeding back this drowsiness output N to the inlet of the load setting device 20, the plant drowsiness output is controlled in a closed loop, and the output adjustment operation is controlled by B. be called.

This Invention C: Fukaru AFC operating condition prediction device uses the following functions to calculate the base output cover turn or base j when inputting the time pattern of the AFC allowable width, mainly in response to the operator's request during AFC operation planning. The time pattern of the l'c allowable width when inputting the read cover pattern is predicted. If the results of the prediction are satisfactory, the base output cover turn at that time is set in the output cover turn generator 8 as a signal of the load target pattern A shown in FIG.

FIG. 4 is a block diagram showing an outline of the AFC operating condition prediction device according to the present invention. The AFC operating condition prediction device according to the present invention includes an operator input device 12, a display device 13,
, a judgment device 14, an AFC permissible range prediction device 15, a base output prediction device 163, and a simulation model 17. When predicting APC operating conditions, the operator inputs AFCif! through the operator input device 12. Input a width priority signal, a color width priority signal, a width priority signal width request pattern, or a base output priority signal and a base output request pattern.

According to these input signals, the determining device 14 performs 1. In the case of giving priority to the υ゛C tolerance width, an AF'C tolerance width request pattern signal is input to the base output prediction device 16 and activated.

Further, in the case of giving priority to the base output, a base output request pattern signal is input to the AF'C permissible width prediction device L5 and activated. These prediction devices 15 and 16 use a simulation model 17 based on the history signal A of the core content parameters obtained from the core monitoring device, and in the case of the device 15, a signal predicting the transition of the AFC allowable width. /116, signals predicting the transition of the base output are output to the judgment device 14, and the judgment device 14 outputs these signals in the form of a time function to the display device 13.

The processing flow of next cAFC tolerance width prediction and base output prediction will be described in detail below.

FIG. 5 is a flowchart showing the procedure for predicting the AFC tolerance range when giving priority to the base output.

First, an operator inputs a base output request pattern as time series data p(ri) using the operator input device 12 (step 101).

Next, the simulation model 17 predicts plant state variables such as core circulation, neutron flux, linear power density MCP, etc., and recirculation pump speed according to the input time series data P (3). Next, these are sent as time series data to the AFC permissible width prediction device 15 (step 102).

The simulation model 17 is a known core multi-dimensional nuclear thermal-hydraulic power, or at least a one-dimensional nuclear thermal-hydraulic transient custom-made analysis model in the axial direction, which can handle changes in xenon reactivity and the like. Then, in the AFC tolerance width prediction device 15, the limit value determined for each parameter is compared with the predicted value from the simulation model 17.
Wow. 3. : From this margin, determine the maximum AJC tolerance range for each parameter within a range that does not exceed the limit value (Step 1)
04). : Next, I will explain the method. The variation amount ΔVi of each parameter during AFC operation is determined by off-line analysis in advance.
It is determined as follows as a function of the variation width ΔP of li''C, and is expressed as a table or a fitting formula.

, aVi=Ai(ΔP, P6.ΔW, CR) ...(
1) In equation (1), Po is the base power, ΔW is the deviation of the core flow rate from the control line, and C is an index representing the rod pattern.

Here, the AFC fluctuation range ΔP is symmetrical up and down, and
Equation (1) is determined by analyzing the FC signal as a rectangular signal, assuming that there is no rest time between the signals, and that signals with different polarities of positive and negative are continuously input.

Since ΔP is symmetrical and its value is not very large, Po
, ΔW, and CkL are constant, the function Ai can be assumed to be a nearly linear monotonically increasing function, and is defined as an inverse function Ai−″fJs (2) with respect to ΔP and ΔVi.

ΔPi = Ai' (ΔVi, P,, ΔW, C)・
...■) Using this equation (2), each gorge AFC tolerance subΔPm is calculated by setting the remainder 4t of each parameter as ΔVi. 1★ (step 105), which has been claimed for all parameters in this way, connects the possible AFC allowable width ΔP(ri) using the monotonically increasing JJD property of the number of meters Ai (the minimum value of Pi(ri) at each time (step 106).

The flow north of this is l'c, the processing flow of the allowable width prediction device.

6, 47, and 8 are flowcharts showing the processing contents and procedures of the base output prediction device 1L16. First, in order to assist the operator in inputting the AFC permissible width request pattern, the relationship between the base output P0 and the AF'C permissible width is calculated and displayed on the CRT (step 201).

This relationship is simplified and calculated as follows using the above-mentioned equation (2).

First, by off-line analysis, the residual MtΔVi for each valley parameter is calculated as P as shown in equation (3) below. ,
The relationship between Δw and akL is tabulated.

ΔVi=Bi (Po, ΔW, C) - (3) Substituting this into equation (2) and taking Po on the flow control line as the equilibrium state of xenon, ΔPi == At -1(13i (f'6 t O+
B], P0,0. Cl-4)...(4) and *hail, given as a function of Po. The A k' C allowable width ΔP is given from ΔPi as an envelope extending through its minimum value as before.

Once the relationship between ΔP and base output is known, the operator can select the appropriate AF.
The C allowable width request pattern ΔP can be input (step 202).

After the input, the maximum base output that satisfies ΔP(0) according to the relationship of equation (4) is set as the 117J period value of Po (step 2
03), start predicting the in-core parameters Δ for seconds using the simulation model 17 (step 204)
. Possible AFC allowable width ΔP from prediction of in-core parameters
'(Processing content up to completion is (steps 205 to 20)
7) is the same as in the case of the AFC allowable width prediction device 15 described above, so the explanation thereof will be omitted. When Δ is completed, this is compared with the AFC permissible width request pattern ΔP(ri) inputted by the operator, and it is checked whether the request is satisfied.

When it is satisfied, it is checked whether there is an excessive margin (step 208).When there is an excessive margin, that is, ΔP' (When S + ε (step 209), it is possible to increase the base output P0, so increase it (step 210). Here, 6 is an appropriate positive value. For details on how to change Po, This will be described later with reference to FIG.

On the other hand, when there is no excessive margin, that is, when the margin is moderate, the set Po is set appropriately and the process proceeds to the next step, and the above-described processing is repeated until A>T (steps 211 to 213).

When the requirements are not satisfied, that is, ΔP7 (S≦ΔP
(In this case, the base output P0 must be raised or lowered to satisfy the demand.M
i=Δpi/(Lee−ΔP(ri), check the sign of the parameter Di defined next for Mt≦0, and calculate P
Decide how to change o.

...(5) Here, for simplification, assuming that Po is changed on the flow control line as a xenon equilibrium state, (5
) is transformed as follows by substituting equation (3). Di
is a parameter that represents the rate at which ΔPi changes when the base output Po changes, so if you check its sign or negative, Po
The direction of change is known (step 214).

In other words, for Mi≦00, if Di) is 0 (step 215), by increasing PO, ΔP5'
Since P becomes large, P is made large (step 216).

On the other hand, if Di(0) for Mi(O, the requirement can be satisfied by reducing Po to a small value (step 217
). The in-core parameters are re-evaluated using the change amount simulation model 17 of P (step 218).
), re-evaluate the AFC tolerance range.

Furthermore, if there is a case where Mi(0) has a different positive or negative value of Di, the direction of necessary change will be different, so it is impossible to satisfy the AFC valley width requirement.

In this case, the process A'i-, fJ, which will be described later, proceeds to the next time step (step 219).

The flowchart in FIG. 7 shows the processing details of step 210 for increasing the base output P0 when there is an excessive margin for Δp/<.

Here, Ei is defined by the following formula, hi≦Mi/Di (7) The basic output P0 necessary to change ΔPi'(ri to ΔP(ri)
represents the amount of change. In this case Ei (Q but E
Since the size of i corresponds to the allowable change amount, the minimum value of 1Eil is taken and set as the base output change amount δP0 (Step 3
01-303).

8 and 49 show the contents of the base output change processing when the Ale" (4 valley width prediction does not satisfy the requirements), and show the details of the processing in steps 217 and 216.

First, Figure 8 shows step 2 when decreasing the base output P0.
17 shows the processing of No. 17. At this time, for all Mi (0), Di (0), so Po is lowered, but for such Mi (0), all gt
Subtract (>o) ('.

Step 401). In this case, Ei corresponds to the required abundance of change, so take its maximum value and set it as E- (
Steps 402, 403).

On the other hand, for Mi)Q, if Di)0, P.

Since the margin becomes smaller by lowering the value by 8, ri()0) is calculated in this case as well (step 404).

At this time, since Ek corresponds to the change allowable arrival, its minimum value is taken as Ek (steps 405 and 406). Next, it is evaluated whether the change allowance #wax E+ exceeds the change required amount n- (step 407).

When E+≧E-, by lowering the base output, A
The F'C tolerance width requirement can be satisfied, and the base output change amount SPo is given as sp, >l(-) from the required change amount E- (step 408).

On the other hand, when E+<H-, the required amount exceeds the permissible amount, so the AFC permissible width requirement cannot be realized. In this case, processing A, which will be described later, is performed (step 409) and the process proceeds to the next time step.

Figure 9 shows step 21 when increasing the base output P0.
6 shows the process, but the process content (step 5
01 to 509) is the g8 described above except for the direction of change of Po.
It is similar to the one shown in the figure. That is, in the case of Figure 9,
Since all Mi(O's are Di)Q, P
In order to increase O, ff1 ((0) is set for all such cases where Mi<00 (step 501).

In this case, since Ei corresponds to the required change amount, the maximum one shift is taken and set as E- (step 502,
503).

On the other hand, for Mi) 0, Di (if it is 0, increasing Po will reduce the margin), and in this case also F2
t(<O) is calculated (step 504).

At this time, since Ei corresponds to the allowable change amount, its minimum value is taken as Ek (steps 505 and 506). Next, it is evaluated whether the change amount 8+E+ exceeds the required change amount E- (step 507).

When E0≧E−, by increasing the base output, A
The FC allowable width request can be satisfied and the base output change ISP from the required change amount E- is given as Sp,=g- (step 50
8).

On the other hand, when E + < E-, the required amount exceeds the allowable amount, so the AFC allowable width request cannot be realized. In this case, processing A, which will be described later, is repeated (step 509) and the process proceeds to the next time step.

Next, process A (step 2) shown in FIGS. 6, 8, and 9.
19,409,509) will be explained. Process A is a process that occurs when a branch is reached where it is impossible to realize the AFC tolerance width request input by the operator depending on the base output operation by recirculation flow rate control, but it is considered based on the characteristics of an actual nuclear power plant. Then, such a case is highly unlikely.

Therefore, processing A is actually unnecessary processing.

In the case of this embodiment, the process A is simply presented to the operator C with an appropriate guide, the base output remains as it is, and the process moves to the next time step.

FIG. 10 and FIG. 11 are graphs showing examples of ANC allowable width prediction and base output prediction by the AFC operating condition prediction device shown in this embodiment.

Figure 10 shows A when inputting the basic output request pattern.
ii” Figure 411 shows the change in the AFC operating width.
4 shows changes in the output when the driving width request pattern is input.

〔Effect of the invention〕

As described above in detail based on the embodiments, if the AFC operating condition prediction device according to the present invention is used, AP'C' permission is It is possible to provide operators with predictions of optimal qAPC operating conditions that take into account an appropriate safety margin that does not exceed each operating limit for either d-width or base output.Therefore, it is possible to create optimal operating plans. This greatly reduces the burden on operators, greatly improves the operability of nuclear power plants without compromising their integrity, and greatly contributes to the maintenance and management of power systems.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the time changes in core thermal output 3, flow rate, xenon density, and iodine concentration when power is changed by manipulating core flow rate, and Figure 2 is a diagram showing the relationship between core thermal output and core flow rate. (2) Figure 3 is a block diagram showing the various operating restriction conditions that exist, Figure 4 is a block diagram showing the reactor power control system, Figure 4 is a configuration block diagram showing one embodiment of the present invention, Figures 5 to 9 is a flowchart showing the stone physics content of the first embodiment of this invention, and the Q"rLO diagram and the Al1 diagram are graphs showing the effects of the first embodiment of this invention. 12... Operator input device, 14...・Judgment device,
15...AFC allowance width prediction device, 16...group) Output prediction device, 17...Simulation model. Applicant's agent Kiyotoki Inomata Question 1 table ・■ Bu)l-pme Figure 4

Claims (1)

[Scope of Claims] 1. In an automatic frequency control operation condition prediction device that calculates and outputs an output turn necessary for automatic frequency control operation on a slave side based on each parameter indicating the core state of a nuclear reactor, an AFC tolerance width request is provided. An operator input device that receives the pattern signal and the basic output request pattern signal, and a dynamic characteristic analysis code that responds to the AFC tolerance width request pattern signal and predicts the core state failure based on the history signal of each parameter listed in CN1j. a base power prediction device that calculates a margin for each of the parameters and, based on this, predicts and outputs a change in the maximum base power within a range that does not deviate from each of the allowable operating ranges of the reactor; and the base power request. Activate the dynamic characteristic analysis code in response to the pattern signal to determine the margin of each parameter, and based on this, predict the transition of the maximum AFC tolerance within the range that does not deviate from each operational tolerance of the reactor. AFC that outputs
a permissible width prediction device; transmitting the AFC permissible width request pattern signal to the base output prediction device; and transmitting the base output request pattern signal to the AF
An automatic frequency control operating condition prediction device comprising: a determination device that transmits the predicted signal to a C tolerance width prediction device and outputs predicted signal outputs from both of the prediction devices as a time function. 2. The automatic frequency control operating condition prediction device according to claim 41, wherein the operator input device receives either an AFC permissible width request pattern signal or a base output request pattern signal with priority.