JPH02202602A - Computing element for change rate - Google Patents

Abstract

PURPOSE:To obtain an output corresponding to the signal change of a long cycle with satisfactory responsibility by installing plural differentiation means which operate the change rate of measurement variables in different time intervals in changing inputs and a weight mean means which optionally weights the outputs. CONSTITUTION:When a process signal P which includes the noise of a short cycle and which increases in the long cycle is inputted, the signal P is decided in change rate decision circuits 1-4 having different time intervals. Then, the gains of attribute degrees of K1-K4 of respective change rates for a physical change are multiplied in amplifiers 5-8. Then, the signals P are added and they are divided by the addition value of the attribute degrees K1-K4 in the mean circuit 10 so as to output the change rate. In the output, the influence of the noise of the short cycle and the like included in the input process signal is removed and the output signal corresponding to the original process quantity change of the long cycle can be obtained with high responsibility.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a process detection device employed in power plants such as nuclear power, thermal power, and hydropower.

(Prior Art) Conventionally, it has been difficult to appropriately detect the rate of change of various process quantities in each plant and apply this to process control because it is affected by various noises.

In other words, in general, the rate of change in the process quantity is expressed as shown in the characteristic diagram in Figure 5, where the horizontal axis is time t and the vertical axis is the process quantity P, and the process quantity changes from Pl to P2 between times t1 and t2. Then.

It can be expressed by the following equation 0.

(Pa - Px) / (tt - tt) ... ■ However, when talking about the rate of change of a certain process quantity, the time interval Δt (tz tt) when calculating this rate of change is not clearly defined. .

As an example, when the change behavior of the process quantity P with respect to time t shows a small change over a short period of time as shown in the characteristic diagram in Figure 6(a), and a case where the change behavior changes significantly over a long period of time as shown in the characteristic diagram in Figure 7(a). The rate of change for each case is divided into two different time intervals (
The results of determination at long-term intervals Δta and short-term intervals Δtb are shown in Figures 6(b), (c) and 7(b), (0), respectively. Although the rate of change determined by Δta is not affected by minute changes in the process amount as shown in FIGS. 6(b) and 7(b), there is a delay in determining the rate of change. On the other hand, as shown in Figures 6 (Q) and 7 (Q), the rate of change determined using the short change rate detection interval Δtb does not have a delay in determination, but it does not respond to minute changes in the process amount. significantly affected.

(Problem to be Solved by the Invention) In general, minute process amount changes as shown in FIG. In order to perform change rate judgment, it is sufficient to make the judgment time interval long, but if this is made too long, the detection of the actual change will be delayed.Furthermore, regarding the change rate detection time interval for this judgment, There is no problem if the period at which the quantity physically changes is significantly different from the noise period, but usually these two periods are close to each other and overlap, as shown in the characteristic diagram in Figure 8. For this reason, if the change rate detection time interval is uniquely determined, the overlapping portion will be divided, and a portion of each other's information will be lost, making this determination extremely difficult. In reality, if the detected process amount changes in a certain period, the possibility that the change is physically meaningful,
The possibility that it is noise is clearly 1 or 0 as shown in Figure 9.
The relationship is such that the probability that it is physically meaningful is 0.9 and the probability that it is noise is 0.1. In addition, each of these possibilities is described here as “
However, this degree of belonging changes continuously depending on the period.For this reason, conventionally, when trying to control a certain object well, the rate of change of the state of the object, that is, the process amount Although it is often necessary to differentiate and feed back this result, it is difficult to eliminate the influence of noise and detect only the true rate of change, so the differential element cannot be used for control. There was a problem.

The present invention has been made in view of the above, and its purpose is to provide a plurality of differentiating means for calculating the rate of change of a measurement variable at different time intervals using changing inputs, and a weighting unit that applies an arbitrary weight to the output. It is an object of the present invention to provide a rate-of-change calculator that eliminates the influence of short-period noise contained in an input signal by means of an averaging means and can obtain an output corresponding to a long-period original signal change with good responsiveness.

[Structure of the invention]

(Means for Solving the Problem) A plurality of differentiating means for calculating the change range of a measured variable at different time intervals, and a weighted average means for assigning arbitrary weights to the outputs of the differentiating means are provided.

(Function) In order to calculate the rate of change only for physically meaningful changes in the input process quantity, a plurality of change rate calculation means are provided for the period range corresponding to the physical change, and the Weights the output based on the degree of attribution to physical changes, eliminates the effects of short-period noise contained in the process signal, and responds with an output signal that corresponds to the original long-period change in process quantity. Get high sex.

(Example) An embodiment of the present invention will be described with reference to the drawings.

Figure 1 is a basic configuration diagram. In order to calculate the rate of change only for physically meaningful changes in process quantities, multiple change rate calculation means are used for the range of cycles corresponding to physical changes. The output is weighted based on the degree of attribution to the physical change, which is expressed by the following equation 0.

kl: degree of attribution of the significance of the rate of change in Δtl as a physical change, P: process amount.

FIG. 2 is a block diagram showing four different rate-of-change detection time intervals.

The time intervals for inputting the process quantity P and detecting the rate of change are shown in FIG.
t4, and change rate determination circuits 1, 2, and 3.4, each of which is a differentiating means, are connected to each other, and each degree of attribution of each change rate to a physical change is determined.

K3. Amplifiers 5, 6゜7 whose gains are determined based on K.
．． 8 and an adder 9 for adding these outputs, and an averaging circuit 10 for normalizing the added output.

Next, the effect of the above configuration will be explained. Figure 4 (a
) When a process signal that includes short-period noise and increases over a long period is input, as shown in the characteristic diagram of Figure 4(c), the conventional device produces an extremely variable output, as shown in Figure 4(c). It is absolutely impossible to apply this method to differential feedback control. However, according to the present invention, FIG.
) is determined in four different time interval rate-of-change determination circuits 1, 2, 3.4, and further processed in amplifiers 5, 6, 7.8, respectively, to convert each rate of change into a physical change. After being multiplied by the gains of the membership degrees Ki, K, , K, , K, they are added in an adder 9, and then added to the averaging circuit 1.
At 0, the degree of belonging is divided by the addition value of , K, , K, , K, and the rate of change is output. The output from this is shown in Figure 4 (b
), the effects of short-period noise contained in the input process signal are eliminated.

The output signal corresponding to the long-period original process quantity change is
Moreover, high responsiveness can be obtained. Therefore, this output signal can be used for differential feedback control to achieve good control.

〔Effect of the invention〕

As described above, according to the present invention, the degree to which a change in a process quantity with a period in which it is unclear whether the change is caused by noise or a physical change is attributed to a physical change is determined. Since an appropriate rate of change can be calculated, differential feedback control, which was previously impossible to achieve, becomes possible, and the effect is that a control system that is optimal for various process controls can be freely constructed and, as a result, good control can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a characteristic diagram of the degree of attribution to physical changes with respect to period time, and Fig. 4 (a) 4(b) is an output characteristic diagram of the rate-of-change calculator of the present invention, FIG. 4(c) is an output characteristic diagram of the conventional rate-of-change calculator, and FIG. Quantity change rate characteristic diagram, Figure 6 (a
) is a characteristic diagram of small changes in process amount, and Fig. 6(b) is a characteristic diagram of small changes in process amount.
Figure (a) is a characteristic diagram of the rate of change in the process quantity determined at long time intervals, Figure 6(c) is a characteristic diagram of the rate of change in the process quantity determined at short intervals in Figure 6(a), and Figure 7 (a) is a characteristic diagram with a large change in process amount over a long period of time, and Figure 7 (b) is a
) is a characteristic diagram of the rate of change of the process quantity determined at long intervals,
Figure 7(c) is a characteristic diagram of the rate of change of the process quantity determined at short intervals in Figure 7(a), Figure 8 is a characteristic diagram of the change period of the input signal, and Figure 9 is the degree of belonging characteristic for the change period. It is a diagram. 1.2, 3.4... Change rate determination circuit. 5.6, 7.8... Amplifier, 9... Adder, IO... Average circuit. Fig. 1 Agent Patent Attorney Ohu Dian Huo Fig. 2 Agony Fig. 3 Condolence Fig. ats:'tii 4. th Time F5Pi% chart chart

Claims (1)

[Claims] 1. A rate-of-change calculator comprising a plurality of differentiating means for calculating the rate of change of a measured variable at different time intervals, and a weighted average means for assigning arbitrary weights to the outputs of the differentiating means.