JPS62279415A - Controlling method for pulsating flow in tube - Google Patents

Abstract

PURPOSE:To eliminate and suppress pulsation in downstream side by presuming pulsation transmission function and the pulsation value of a downstream side observation point from input/output characteristic between two points of upstream side and downstream side in a conduit, converting it to pulsation by inverting the sign, and adding to just after the downstream side observation point. CONSTITUTION:When the time of observation is (k), the pulsation transmission function G in a conduit is G=y(k)/u(k). Pulsating flow of u(k) is generated at a point A in a linear regression conduit, and a pulsation value of y(k) is generated at a point B. Accordingly, at the time of operation, the function G is determined beforehand from u(k), y(k) and put in a controlling and arithmetic unit 3, and u(k) is inputted. Pulsating flow u(k) of point A generated in fluid that flows in the conduit 1 is sent to the controlling and arithmetic unit 3, and pulsating flow at the point B of the conduit 1 is operated and presumed by y(k)=G.u(k) and outputted. Then, it is converted to -y(k) by an inverter 4, and given to a servovalve 10 as a command signal. Consequently, the fluid from a fluid source 9 is controlled by the servovalve 10 and led to the control room 7 of a pulsation compensating section 5. As an elastic body 8 eliminates pulsation at a point B, the pulsation of fluid after a point C in a conduit 2 is suppressed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for actively controlling pulsating flow within a tube.

[Conventional technology] Fluid transport devices for chemical plants, piping systems for various industrial machines, hydraulic systems, cooling systems for nuclear power plants, etc.
Various pulsation damping means are employed in all piping systems involving fluid transport.

To explain the conventional pulsation damping means, FIGS. 4 and 5 show an accumulator type, in which an accumulator b is attached to the middle of the pipe a, and the volume d formed by the rubber membrane C in the accumulator b is is filled with gas, and the pressure of the gas prevents pulsating pressure. e in Figure 5
is the orifice.

Figure 6 shows a branch pipe system, in which a branch pipe r is provided in the middle of pipe a, and by adjusting the length of the branch pipe r, acoustic resonance occurs in the branch pipe r, and pulsating energy is Attenuated.

In addition to the above, there is also a method in which an orifice is provided in the middle of the conduit to attenuate pulsation by throttling resistance.

[Problems to be Solved by the Invention] However, with the above-mentioned pulsation damping means, (1) there is a limit to the amount of pulsation attenuation because each of them has unique characteristics, and it is difficult to attenuate pulsations of all target frequencies; C] In order to obtain effective pulsation attenuation, it is necessary to design the attenuator so that the characteristics of the pipe system where pulsation occurs and the characteristics of the attenuator have an optimal relationship. It may not be possible to obtain a large amount of pulsation attenuation due to calculation errors, changes in usage conditions, etc. (To) Conventional attenuators are passive type, and there is a limit to the amount of pulsation attenuation. (To) Due to changes in conditions There were problems such as not being able to adapt.

In view of the above-mentioned circumstances, the present invention provides a method for actively controlling pulsating flow in a pipe, which can obtain a large amount of pulsation attenuation for pulsations of all frequencies and can easily adapt to changes in conditions. This was done for that purpose.

[Means for Solving the Problems] The present invention identifies the human output characteristics of pulsating flow between two points on the upstream side and the downstream side in a pipeline using statistical methods from all values, and The pulsating flow observation value at point J+ from the second-stream side of the pipe is manually input to a control calculator incorporating the pulsation transfer function determined from the output characteristics to predict the pulsation value at the observation point on the downstream side of the pipe, and the predicted pulsation is calculated. The output signal with the sign of the value reversed is converted into pulsation and added immediately after the downstream observation point in the pipeline, and the output signal is added to the downstream side of the pipeline from the downstream observation point due to the pulsation occurring at the upstream observation point of the pipeline. It has a structure that cancels out and suppresses side pulsations.

[Operation] The input/output characteristics of the pulsating flow are identified using a statistical method from the pulsating flow observed at two points on the upstream side and downstream side in the pipe, and the pulsating transfer function determined from the human output characteristics. The pulsation value at the observation point on the downstream side of the pipe is predicted based on the observed value of the pulsating flow at the observation point on the upstream side of the pipe, the sign of the predicted pulsation value is inverted and output, and the output signal is converted to pulsation. It is applied immediately after the observation point on the downstream side of the pipe, canceling out and suppressing pulsations.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, where 1 is a conduit through which fluid flows from left to right in FIG. 1 and pulsation occurs to the left of point B; 2 is in communication with conduit 1; By implementing the control method, the pulsation is suppressed on the right side of the 0 point in the pipeline, and 3 is designed to incorporate the pulsation transmission model between AB, which is calculated based on the pulsating flow observed at point A of the pipeline 1. 4 is an inverter that inverts the signal output from the control calculator 3;
Reference numeral 5 denotes a pulsation compensator provided between the BCs of the conduits 1 and 2, which is a device that converts the signal from the inverter 4 into a pulsating pressure or a pulsating flow rate.

Details of the pulsation compensation section 5 are shown in FIG. 2, and the fluid circulation section 6 and the control chamber 7 are partitioned off by an elastic body 8 such as a rubber membrane.

A servo valve 10 for controlling the fluid pressure or flow rate from the fluid source 9 is connected to the control chamber 7, and an output signal inverted by the inverter 4 can be given to the servo valve 10.

In order to cancel and suppress pulsation, first observe the pulsating flow at points A and B in conduit 1, and identify the input/output characteristics of the pulsating flow in conduit 1 from the observed values using statistical methods. However, it is necessary to incorporate the identified pulsation transmission model into the control calculator 3.

Now, let the pulsating flow at point A be u (k) and the pulsating flow at point B be y (k). Here, k means the observation time, and u
(k),! / (k) means the ap+ value at the time. In addition, by introducing a delay operator Z expressed as Z-' Y (k) -y (k-1), the following linear regression model can be used as an identification method using statistical methods. can. However, y(k-1) is an observed value one point before k.

y (k) --(a, Z-' +a2 Z-2+-
・・+anZ(l) y (k)+ (b+ Z-'
+ bz Z-' +...-+bn Z-n) u (
k) + v (k) Here, a and b are the parameters of the regression model, and are determined, for example, by the least squares method, that is, so that the square of the model error v (k) is minimized, and the pulsation transfer function of the pipe G is.

The linear regression model described above is a dynamic model of the pipeline, and A
If a pulsating flow of u (k) is observed at point B, y (
k) pulsation value will occur. Therefore, during operation, the pulsation transfer function G is determined in advance from u (k) and y (k) as described above, and the pulsation transfer function G is incorporated into the control calculator 3 and u (k) is input.

Pulsating flow u (
k) is sent to the control calculator 3, and in the control calculator 3, V
(k) −G−u (k) calculates and predicts the pulsating flow at point B of the pipe [, and outputs it, and the inverter 4 outputs −Y (
k) and given to the servo valve 10 as a command signal. Therefore, the fluid from the fluid source 9 is controlled by the servo valve 10 and introduced into the control chamber 7 of the pulsation compensator 5, and the elastic body 8 operates to cancel the pulsation at point B.
Fluid pulsation is suppressed after the 0 point.

Next, to explain the above-mentioned suppression of pulsation with reference to FIGS. If the pulsating flow at point B has a waveform with a pulsating propagation time of δ as shown in FIG.
The pulsation command given to 0 is as shown in FIG. 3(c). Therefore, at the 0 point of conduit 2, the waveform shown in Fig. 3 (b) and the waveform shown in Fig. 3 Q\) are combined, and the pulsation is suppressed as shown in Fig. 3)). be done.

In the embodiments of the present invention, the case where the pulsation transfer model is identified off-line has been explained, but it is also possible to identify the pulsation transfer model on-line during operation and replace the pulsation transfer model with the control eJ calculator at appropriate time intervals. It is also possible to use a piston instead of an elastic body in the control chamber of the pulsation compensator, it is possible to adopt any waveform other than a sine wave, and other aspects do not depart from the gist of the present invention. Of course, various changes can be made.

[Effects of the Invention] According to the method for controlling pulsating flow in a pipe according to the present invention, (D) pulsation can be actively attenuated over all frequencies, resulting in a large pulsation suppressing effect; (II) Pulsation in a pipe The model is not calculated from the equation of motion (it is calculated by applying uniform processing from the observed values, etc.), so the model is accurate and can be adapted to changes in operating conditions and states. ■ General Generally speaking, as an active damping device, when pulsation compensation is added, the pulsation input value itself changes, and it is necessary to find the compensation value by trial and error. However, in the present invention, the conduit transmission model itself is compensated. The pulsation value at other points, which changes when compensation is added, is input to the control system, and the expected pulsation output value is compensated for, so the pulsation is automatically attenuated. (2) The ability to control not only pulsation but also transient flow, etc., can produce various excellent effects.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the method for controlling pulsating flow in a pipe according to the present invention, Fig. 2 is an explanatory diagram of the pulsation compensator in Fig. 1, and Fig. 3 (A) <0
) (A) Figure 6 is a graph showing the pulsation state when performing the method of controlling pulsating flow in a tube according to the present invention, and Figures 4, 5, and 6 are explanatory diagrams of conventional examples. In the figure, 1 and 2 are pipes, 3 is a control calculator, 4 is an inverter, 5 is a pulsation compensator, 7 is a control chamber, 8 is an elastic body, 9 is a fluid source, 1
0 indicates a servo valve.

Claims (1)

[Claims] 1) The input/output characteristics of the pulsating flow between two points on the upstream and downstream sides of the pipeline were identified using statistical methods from the observed values, and the pulsating transfer function determined from the identified input/output characteristics was incorporated. The pulsating flow observed value at the observation point on the upstream side of the pipe is input into the control calculator to predict the pulsation value at the observation point on the downstream side of the pipe, and the output signal with the sign of the predicted pulsation value inverted is converted into pulsation. In addition to immediately after the downstream observation point in the pipeline, the pulsation downstream of the downstream observation point in the pipeline due to pulsations occurring at the upstream observation point in the pipeline is canceled out and suppressed. Method for controlling pulsating flow in a tube.