JP2002005075A - System for controlling pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump control system which can suppress or prevent differences of discharge between respective pumps with respect to different pump-inlet water levels in an operation system of a plurality of variable speed pumps. SOLUTION: Arithmetical units 5, 6 for calculating a rotational speed of a pump according to a pump-inlet water level signal for the respective pumps, a signal for a number of the running pumps, and a rotational speed command signal received from a regulator are provided to a plurality of variable speed pumps 1 which have different pump-inlet water levels and are driven via variable speed driving units 4. Control of pressure is executed based on the rotational speed of a pump calculated by the arithmetical units 5, 6 to equalize the discharged flow rate of a plurality of variable speed pumps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for operating a plurality of variable speed pumps, and more particularly to a pump control system capable of suppressing or preventing a difference in discharge rate between respective pumps at different pump primary water levels.

[0002]

2. Description of the Related Art Generally, an automatic water supply system using a plurality of pumps is well known. However, when a conventional system is controlled by giving a rotation speed command signal for the same pressure control, the water level on the primary side of the pump is reduced. It has been pointed out that there is a problem that the discharge flow rate increases and decreases, and in the case of pumps of the same rating, a difference occurs in the discharge flow rate.

[0003]

That is, the conventional system has a problem that a difference in discharge flow rate occurs depending on the level of the water level on the primary side of the pump, so that uniform pump operation cannot be achieved. Accordingly, an object of the present invention is to operate a plurality of variable speed pumps having different pump primary water levels by changing the pump rotation speed in accordance with the pump primary water level, thereby suppressing unnecessary rotation and energy. The present invention aims to make pump operation more uniform and to make the pump operation uniform by suppressing or preventing a difference in discharge flow rate.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a variable-speed drive in which the pump primary water level or the pump primary pressure (hereinafter referred to simply as the pump primary water level) is different. For a plurality of variable speed pumps driven via the device, an arithmetic unit for calculating the pump rotation speed by inputting the pump primary side water level signal, the number of operating units signal and the rotation speed command signal from the controller is provided. Pressure control is performed based on the pump rotation speed calculated by the calculation device, and the discharge flow rates or discharge pressures (abbreviated as discharge flow rates in this specification) of the plurality of variable speed pumps are uniformly controlled. (Claim 1).

In order to solve the above-mentioned problem, according to the present invention, the pressure control can be a discharge pressure constant control or an estimated terminal pressure constant control (claim 2).

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, typical embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating an embodiment of the present invention, and FIG. 3 is an explanatory diagram of an arithmetic system according to the embodiment. In these figures, 1 is a variable speed pump, 2 is a pump well A, 3 is a pump well B, 4 is a variable speed drive, 5 is an arithmetic unit A, 6
Is a computing unit B, 7 is a water level gauge for pump well A, 8 is a water level gauge for pump well B, 9 is a controller, 10 is a pressure gauge, and 11 is a flow meter.

As described above, in the embodiment of the present invention, two types of pump wells, pump well A2 and pump well B3, are used as the pump wells for supplying water. One or more units (A1 to AN, B1 to BN) are provided for each pump well B3. As shown in FIG. 3, each variable speed pump 1 (A1 to AN, B1 to BN
No.) is adjusting meter 9 and the rotational speed command signal I _A to the variable speed computing device belonging to a sequence of the pump well, which is connected to a pump (obtained via computing device A5 or the arithmetic unit _B6), I B _(Analog Signal), the pressure control operation is performed.

[0008] Here, during one operation, from to water level signal (pump inlet pressure) to H _A speed command signal I and the pump well A2 to pump well B3 are input from the adjusting meter 9 H _B, computing device A5 Or by the arithmetic unit B6
Obtains the following formula (1) or (2) the rotational speed was corrected by the water level on the basis of a formula command signal I _A or I _B, and enter the corresponding variable speed drive 4 the rotational speed of the pump it Control each.

I _A = [1 + {(K _A1-1 ) ( _HA− H ₀ )} / (H _AL −H ₀ )] I (1) where H _A > H ₀ where I _A : Revolution speed command signal from the arithmetic unit A I: Revolution speed command signal from the controller K _A1 : Correction coefficient when operating one unit (K _A2 , K _A3.
And _{AN) H A:} pump well A water level (pump inlet pressure) _{H 0:} normal level H _AL: high water I _A = I · · · of the pump well A (2) _where noted H A <= _{H 0} in the case of the pump well B (1) and _{(2), I a → I B, K} A1 → K B1, H a → H B,
The formula replaced with H _AL → H _BL is applied.

In this case, H ₀ > = H _AL or H ₀ > =
Under the condition of _HBL , each arithmetic unit A or arithmetic unit B can be omitted, and the rotational speed command signal from the controller can be directly input to the variable speed driving device 4 to control the rotational speed of the pump. It is.

The correction coefficient K_A1Is shown, for example, in FIG.
Pump performance curve (QH curve) and loss curve flow rate
And the rotational speed ratio, N_H/ N_C, N_H’/ N
_C'... N_H0/ N_C0Or the average value of
Calculation formula. Where N _C, N_HIs the QH curve
The vertical line passing through the intersection of the low water loss curve is the specified water level and the maximum
The point of intersection with each water level loss curve
Assuming that the output flow rate is Q, Q '= 2Q / 3 and Q "= Q / 3.
The vertical line passing through Q ', Q "shown is the specified water level and the maximum water
Where the intersections with the loss curves of the_C’,
N_H’, N_C", N_HAnd the specified water level and
Each intersection point where the highest water level loss curve intersects the Q = 0 axis
Re N_C0, N_H0Becomes The pumps 2, 3... N
Pump performance according to the number of units even when running
It can be similarly obtained from the curve and the loss curve.
Note that the correction coefficient K_A1Or K_ANOr K_B1Or K
_BNIf the values of
A common correction coefficient can be used.

In the above embodiment, an example using two types of pump wells, pump well A and pump well B, has been described. When three or more types of pump wells are used, for example, pump well n is In the above formulas (1) and (2), I _A
→ I _n , K _A1 → K _n1 , H _A → H _n , H _AL → H _nL
Apply the replaced expression to.

[0013]

As described above, the pump control system according to the present invention is configured such that the pump speed command signal can be determined and controlled in accordance with the pump primary water level, so that a plurality of pumps at different pump primary water levels can be controlled. The discharge amount between the pumps can be made uniform, and an effect of effectively utilizing energy can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram illustrating an arithmetic operation according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of an arithmetic system according to the embodiment of the present invention.

[Explanation of symbols]

1: variable speed pump, 2: pump well A, 3: pump well B,
4: Variable speed drive, 5: Arithmetic unit A, 6: Arithmetic unit B, 7: Water level meter A, 8: Water level meter B, 9: Controller, 10:
Pressure gauge, 11: flow meter

Claims (2)

[Claims] 1. A pump primary water level signal, operating number signal and controller for a plurality of variable speed pumps driven via a variable speed drive device having different pump primary water levels or pump primary pressures. A calculation device for calculating the pump rotation speed by inputting a rotation speed command signal from the controller is provided, and pressure control is performed based on the pump rotation speed calculated by the calculation device, and the discharge flow rate or discharge of the plurality of variable speed pumps is controlled. A pump control method characterized by uniformly controlling the pressure. 2. The method according to claim 1, wherein the pressure control is a discharge pressure constant control or an estimated terminal pressure constant control.
The described pump control method.