PI Controller In Terms Research Articles

Robust Fractional Order PI Controller for a Main Irrigation Canal Pool

A new method is proposed to design a class of robust fractional order PI controller (FPI) based on frequency specifications for water distribution in a main irrigation canal pool. The robustness features of the obtained FPI controller are compared with the ones of an equivalent standard PI controller with the same design frequency specifications. A justification of its enhanced properties it is also provided. The interest of such fractional order controllers is justified by the fact that dynamical parameters of main irrigation canal pools may change drastically in function of its operation regimes. The designed FPI controller was implemented in a PLC of the Siemens company (Simatic 300) and was installed in a real main irrigation canal pool. The real time experimental results carried out comparing both FPI and standard PI controllers for different discharge regimes showed the superiority of the obtained FPI controller over the standard PI controller in terms of time domain performance and robustness. These results proved that the proposed design method leads to an efficient realistic FPI controller for main irrigation canal pools.

Design of decentralized PI control systems based on Nyquist stability analysis

Abstract This paper presents a simple, but effective, design method for decentralized PI control systems with guaranteed closed-loop stability. Nyquist stability conditions are used to derive the stability region for each PI controller in terms of the controller parameters. A detuning factor for each loop is specified based on a diagonal dominance index. Then appropriate controller settings are determined using this index and the stability region. Simulation results for a variety of 2 × 2, 3 × 3, and 4 × 4 systems demonstrate that the proposed design method guarantees closed-loop stability and provides good set-point and load responses.

Generic distributed parameter model control of a biological nutrient removal (BNR) activated sludge process

This paper addresses nonlinear control of a class of distributed parameter systems by the generic distributed parameter model-based control (GDPMC) strategy. Case studies on a complex biological nutrient removal (BNR) activated sludge process for nitrogen and phosphorus removal show that the GDPMC strategy is applicable for controlling species of interest in specific bioreaction zones. The designs give much improved performances compared to well-tuned PI controllers in terms of the integral time absolute errors (ITAE). In a study on control of the entire BNR activated sludge plant, a multi-unit decentralised GDPMC strategy is shown to be robust to 25% plant-model mismatch in three sensitive and uncertain kinetic parameters. The advantages of the GDPMC strategy over lumped-model generic model control (GMC) are demonstrated in a comparative study on soluble phosphate control within the anaerobic zone of the plant.