JPS59105107A - Method for controlling opening of discharge valve - Google Patents

Abstract

PURPOSE:To control a discharging flow rate constantly so as to be an objective value and to attain stable flow rate control by determining the initial opening operation variable to be applied to each discharge valve by a formula approximate to the relation between a previously found discharge valve opening and a discharging flow rate to control the flow rate. CONSTITUTION:Water discharged from a pump well 1 is controlled by plural parallel pumps 2 and their discharge valves 3 to set up the total discharging flow rate constantly to an objective value. Under the control, the total discharging flow rate is detected by a flow meter 4 and inputted to a controller PL to control the opening of each discharge valve 3. In this case, the relation between the openings U1, U2/2 of the discharge valves 3 and the discharge flow rates Q1, Q2 is previously found out by an approximate formula, and when a pump 2 is newly added to be driven, the initial opening operation variable determined from said formula is applied to each discharge valve 3 to control the flow rate stably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a method for controlling the opening degree of a discharge valve in equipment in which a plurality of pumps whose flow rates are controlled by discharge valves are arranged in parallel.

[Technical disadvantages of the invention and the inconvenience]

FIG. 1 shows an example of the system configuration of this type of equipment. As shown in the figure, this equipment includes a plurality of pumps (three pumps in the figure) 2 which control the flow rate of water discharged from a pump well 1 by a discharge valve 3 in parallel via water channels. )is,
4 is a flow meter that detects the total discharge flow rate of this equipment.The output signal of this flow meter is input to the controller PI, and the opening degree of each discharge valve 3 is controlled by the output signal to determine the total discharge flow rate. is controlled to a constant target value.

In equipment with such a configuration, the discharge valve opening degree controlled discharge is calculated from the PI (proportional, integral) calculation V of the following formula, for example.

e(t) = Qsv −Qpv (t,)ΔU =
Kp-(e(t)-e (t-1)+ 1-e(t)-
Δt) UMV2IJpv+ΔU However, Qsv is the target discharge flow rate, Qpv(t) is the discharge flow rate at time t, e(t) is the discharge flow rate/deviation at time t, Kp is the proportional constant, TI is the integral constant, and Δt is In the control circuit, ΔU is the opening operation variation, Upv is the average value of the opening of the discharge valve operating at time t, and UMV is the [)1'' degree operation amount, respectively. Then, each discharge valve 3 is controlled by the controller PIVc with the opening degree operation i7i:UM'V calculated by the previous formula, that is, the discharge valve 3 is Jj! i rlij degrees fti control.

In this case, the average value of the currently operating discharge valve openings is used as the discharge valve opening TJpv for the two current discharge valve openings.

For example, at time t-1, one pump is operating and 0
, considering the case where one pump 2 is additionally operated at time t, the discharge valve opening degree of the additionally rotated pump 3 is close to zero, so the above iffff valve opening degree v: is given by the following formula.

UPv-UI+U2 = U+ 2 2 Here, Ul is the opening of the discharge valve of the pump that was operating at time t-1! ! % U 2 is the opening degree of the discharge valve of the pump additionally operated at time t.

Now, the discharge biragin at the opening degree U1 is Ql, and the opening degree (U
+/ 2) If the discharged liquid at K is Q2, it becomes as shown in FIG. As time t elapses, the openings U1 and U2 approach tJpv+ΔU, that is, U1/2+ΔU, and as a result, the total discharge flow approaches Q2*2VC from Ql. Therefore, the total discharge flow M changes regardless of the flow target/target value Qsv. The above is illustrated in Figure 3.

Therefore, in the above-mentioned discharge valve opening range,
The change in the discharge flow rate with respect to the opening degree of the discharge valve is linear.
However, when controlling a discharge valve with a non-force type function as shown in Fig. 2, Q-)
There is a problem that when the number of pumps 2 is changed, the total discharge flow rate fluctuates rapidly as shown in FIG.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and its purpose is to maintain stable flow t by controlling the total discharge flow to a target value even when the number of tilted pumps changes.
It is an object of the present invention to provide a method for controlling the opening degree of a discharge valve.

[First Requirement of the Invention] In order to achieve the above ACu objective, the present invention uses a discharge valve having non-linear timing. In a setup where a plurality of pumps controlling No.
When a predetermined number of new pumps are added and operated in a device that uses
The relationship between W and the discharge moped is determined by an equation that approximates 1 to the initial opening amount given to each discharge valve, and the desired opening amount is given to each discharge valve. The 9th child is Lee Moon.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to an actual Mq example shown in the drawings. The system configuration of the equipment according to the present invention is the same as that shown in FIG. 1 described above, so the illustration and explanation thereof will be omitted here.

The discharge valve flow film control according to the present invention is performed as described below. In other words, the discharge valve 3 causes a flow of 1lill f.
In a facility in which a plurality of pumps 2 are configured in parallel via water channels, the relationship between the opening degree of the discharge valve 3 and the discharge flow is approximated by the following equation.

c, -a・(Upv　)　1/b However, a and b are parameters that cannot be approximated.

Next, let the current number of PON 120 rotating units be N (t), and the number of quick pumps after the change in the base plate as N (t + t), and use the following formula to apply the initial t-tllJ opening degree to the discharge valve 3 after the change in the number of units. Calculate the total using the formula below.

u, ,, vP-(1vr, s=,, , 5) bHere, UMVP is the initial opening period ht, and Qsv is the 1-vote 1 city.

When the number of operating pumps 2 changes, the above initial to+opening FA (UMVP) is given and ILI-,,H"r
Valve 3 is ↑till Gl, and its ridge is the discharge valve opening average value [Jpv described above, and P by the controller P engineer.
I Operate the opening degree of the discharge valve 3 by changing the opening degree (j@UMV).

In this way, a plurality of pumps 2 whose flow rates are controlled by discharge valves 3 having non-linear characteristics are configured in parallel via water channels.
In a device that controls the opening degree of the discharge valve 3 to maintain a constant control, when a predetermined number of new pumps 2 are added and operated, the relationship r between the discharge valve opening degree determined in advance and the original discharge size is determined by an approximate formula. Initial concave opening degree control function for each discharge valve 3
MVP is determined and the manipulated variable UMVP is given to each discharge valve 3 for control.

Therefore, since the opening control piece that can be used when the number of pumps 2 in operation changes, the total discharge flow rate remains unchanged even when the number of pumps in operation changes, and the MIL is stable.
, cI'l: <0 control can be performed.

〔Effect of the invention〕

As explained above, according to the present invention, uJ IL! is given to each discharge valve using a formula that approximates the relationship between the discharge valve opening requirement and the actual discharge size determined in advance when the number of operating pumps changes. ] Since the opening operation amount is determined and the concession amount is controlled monthly, the total discharge flow can be controlled at the target value even when the number of pumps in operation changes, and stable Haramachi control can be achieved. It is possible to provide a method for controlling the opening degree of the discharge valve that can be easily performed.

[Brief explanation of drawings]

Figure 1 shows the system configuration of equipment to which the present invention is applied.
Figure 2 is a diagram showing the characteristic curve of the discharge valve, and Figure 3 is a diagram showing the change in the flow rate of the stand where the conventional discharge valve opening control was performed. 1... Pump well, 2. ...Pump, 3...Discharge valve,
4...(IIE punching meter, P engineer...controller.

Claims (1)

[Claims] Addition of a new predetermined number of pumps to equipment that controls the opening degree of the discharge valves so that the total discharge flow rate is controlled to a constant target value in equipment consisting of multiple pumps configured in parallel to control the υ flow rate using discharge valves. In the case of operation, the initial opening operation amount to be given to each discharge valve is determined by a formula that approximates the relationship between the discharge valve opening degree and the discharge flow rate determined in advance, and the operation amount is applied to each discharge valve. : A discharge valve opening control method characterized by performing f control.