QUASI-INVARIANT CONTROL METHOD OF WASTEWATER AERATION PROCESS

This invention relates to electrical engineering and can be used in the wastewater biological treatment technology. The aim of the invention is to increase the quality and efficiency of the wastwater aeration process by using invariant control of air blower under variable wastewater inflow and biological oxygen demand. In the proposed quasi-invariant control system (Fig.1) the control impact Lg to the aeration tank (1) is being formed through the air distribution system (9) with air blower (8), the output volume of which is being changed by varying the input voltage and frequency of the asynchronous motor (7) with converter (6) being controlled by PID controller (4). Oxygen concentration measured by axygen sensor (2) is transformed to electrical signal UO2 which is being transmitted to the input of the first differential scheme (3). Differential scheme (3) is forming the difference of the support signal UO2nom and the input signal UO2, which is being transmitted to the control block with the first adder (5), and being adjusted by the output signal deltaUk of the compensation scheme (15) depending on the algebric sum, fomed by the second adder (14) from the inflow change signal deltaUQ, measured by the inflow sensor (12) and the second differential scheme (13), and the output signal deltaULa of the differentiating circuit (10) with signal amplitude restriction unit (11) indirectly identifying change of biological oxygen demand La.