Nonlinear PI Control with Adaptive Interaction Algorithm for Multivariable Wastewater Treatment Process

Abstract

The wastewater treatment plant (WWTP) is highly known with the nonlinearity of the control parameters, thus it is difficult to be controlled. In this paper, the enhancement of nonlinear PI controller (ENon-PI) to compensate the nonlinearity of the activated sludge WWTP is proposed. The ENon-PI controller is designed by cascading a sector-bounded nonlinear gain to linear PI controller. The rate variation of the nonlinear gainknis automatically updated based on adaptive interaction algorithm. Initiative to simplify the ENon-PI control structure by adaptingknhas been proved by significant improvement under various dynamic influents. More than 30% of integral square error and 14% of integral absolute error are reduced compared to benchmark PI for DO control and nitrate in nitrogen removal control. Better average effluent qualities, less number of effluent violations, and lower aeration energy consumption resulted.

Enhancement in pneumatic positioning system using nonlinear gain constrained model predictive controller: experimental validation

“…The control law in (23) can also be represented in the form of linear state feedback control as expressed in (24),…”

“…As shown in Figure 5, a function called nonlinear gain was employed in this study to compensate the nonlinearities and uncertainties in the system parameters. It was utilized to control the error signal ( ) between the predicted output ( ) and set-point signal ( ) in (24). It is of utmost importance to control ( ) due to its influence on the formation of the control signal to the pneumatic system.…”

“…The study also demonstrated the enhancement of pneumatic positioning system in the transient response of the system where the nonlinear gain function and PID controller were combined to control the cylinder stroke of pneumatic system with a payload of maximum weight up to 28 kg at the end of the pneumatic cylinder stroke. The effectiveness of the proposed approach by Seraji [19] in reducing the overshoot and producing better tracking in the system performance was proven using various applications, such as in robotics, milling systems, and wastewater treatment process [22]- [24]. Given such considerations, this study incorporated a nonlinear gain in the conventional constrained MPC (CMPC) as a new control strategy to improve speed response and accuracy of the pneumatic positioning system.…”

A new technique to reduce overshoot in pneumatic positioning system

“…Furthermore, reduction was observed in operation time of the cylinder stroke to reach the steady-state value. Moreover, this effectively reduce the overshoot in performance of the system, while this has been proven in various applications such as in robotics, milling systems, activated sludge and wastewater treatment process [19][20][21][22].…”

Computerized control strategy to prevent wastewater plants pollution

“…Combined sewer systems are designed to carry both raw sewage and storm water runoff to sewage treatment plants. New control methods are implemented in wastewater treatment plants [1][2] [3], and effects of environmental factors have been also studied [4]. But even with the proposed methodologies, during heavy rainstorms these systems can become hydraulically overloaded and discharge a mixture of raw sewage and polluted runoff from streets into local waterways.…”