JPS56116118A - Water level controller - Google Patents

Abstract

PURPOSE:To realize a constant time during which a target water level is obtained regardless of the flow rate, by obtaining a presumed opening amount necessary for adjustment of a target water level by storing the control property of the water level control valve and then controlling the opening amount of the valve to the presumed opening amount to carry out a feedback control. CONSTITUTION:The water level control valve 4 is controlled by the controller 1. The controller 1 decides the valve opening amount theta based on the target water level command H and the flow rate detection value Q of the flow rate meter 9 provided to the water level transmitter 5 installed at the pump basin 6, and the amount theta is controlled to be set at the level under the target water level H0. Then a proportional integral/differential calculus PID control is given when the difference between the target water level and the real water level is the constant alpha1 or less; while a presumed opening amount is obtained when the difference is alpha1 or more. After this, the valve is kept at the presumed opening amount to observe the change of level for a prescribed time. In case the water level does not approximate to the target water level, a calculation is carried out again to set the valve again. Then a PID control is given the difference between the target and real levels is less than the prescribed value alpha2; while a presumed opening amount is calculated again when the real level becomes further away from the target level. In such way, the time during which the target water level is obtained can be set constant regardless of the flow rate of water.