Three degrees of freedom Virtual Reference Feedback Tuning design and its application to wastewater treatment plant control

Abstract

AbstractIn this paper, a three degrees of freedom (two degrees of freedom plus disturbance feedforward action) controller, tuned with the Virtual Reference Feedback Tuning is presented and applied to a wastewater treatment plant. The chosen framework is the one established in the Benchmark Simulation Model 1. Two loops were applied: control of nitrate concentration at the last anoxic section of the plant by manipulating the internal recycle flow rate using a two-degrees of freedom PI and a cascade plus feedforward approach to control ammonia at the last aeration section by manipulating the setpoint of the dissolved oxygen controller at the last aeration section using ammonia measurements from the influent. The results are very close to other more advanced approaches applied to the plant in the same conditions, therefore showing the usability of model-free approach for wastewater treatment plant control.