Performance assessment of cascade controllers for nitrate control in a wastewater treatment process

Abstract

A cascade control strategy is proposed to the benchmark simulation model 1 (BSM1) to enhance the treatment performance of nitrogen removal in a biological wastewater treatment plant. The proposed control approach consists of two control loops, a primary outer loop and a secondary inner loop. The method has two controllers of which the primary loop has a model predictive control (MPC) controller and the secondary loop has a proportional-integralderivative (PID) controller, which is a cascade MPC-PID controller. The primary MPC controller is to control the nitrate concentration in the effluent, and the secondary PID controller is to control the nitrate concentration in the final anoxic compartment. The proposed method controls the nitrate concentrations in the effluent as well as in the final anoxic reactor simultaneously to strictly satisfy the quality of the effluent as well as to remove the effects of disturbances more quickly by manipulating the external carbon dosage rate. Because the control performance assessment (CPA) technique has the features of determining the capability of the current controller and locating the best achievable performance, the other novelty of this paper is to suggest a relative closed-loop potential index (RCPI) which updates the CPA technology into a closed-loop cascade controller. The proposed method is compared with a cascade PID-PID control strategy and the original PID controller in BSM1 and an improved performance of the suggested cascade MPC-PID controller is obtained by using the CPA approach.

Finding the optimal set points of a thermal and ventilation control system under changing outdoor weather conditions

“…Recently, Liu and Yoo 39 applied the original PEA algorithm in order to evaluate the control performance of a series of cascade control structures in a wastewater treatment process. The primary steps of the PEA algorithm can be found in the studies by Huang et al.…”

“…38 and Liu and Yoo. 39 In order to avoid potential ambiguity, some key equations for a multivariable process regarding the calculation of the closed-loop potential in the PEA are listed below.…”

“…The primary steps of the PEA algorithm can be found in the studies by Huang et al 38 and Liu and Yoo. 39 In order to avoid potential ambiguity,…”

Control performance evaluation of reverse osmosis desalination system based on model predictive control and PID controllers

“…(2016) [1][2][3][4][5][6][7][8] www.deswater.com doi: 10.1080/19443994.2016.1191776 the best ways to compare the performance of the controllers which are used to control the RO systems. Aiming at evaluating controller performance from route closed-loop data, control performance assessment (CPA), as a relatively young branch of research, has attached growing interest in control system monitoring and maintenance in the past few years.…”

“…Aiming at evaluating controller performance from route closed-loop data, control performance assessment (CPA), as a relatively young branch of research, has attached growing interest in control system monitoring and maintenance in the past few years. Based on the variance of output error, CPA techniques are used to find how current controller performance compares to the ideal control performance [5].…”