Passing from a Gas to an Electric Water Heater System: Adaptive PID Versus Smit...

• Author(s): Vieira, José ; Mota, Alexandre
• Date: 2007
• Persistent ID: http://hdl.handle.net/10400.11/1012
• Origin: Repositório Científico do Instituto Politécnico de Castelo Branco
• Subject(s): Adaptive PID; Electrical water heater; Physical model identification; Smith predictive control
• Document Type: Article
• Language: English

Description

“Copyright © [2007] IEEE. Reprinted from 11th International Conference on Intelligent Engineering Systems , 2007. ISBN:1-4244-1147-5 This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [e-mail]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.” This paper presents the control results of an electric water heater system using two approaches: adaptable proportional integral derivative and Smith predictive control based in the physical internal model control structure. The electric water heater was modelled with two variable blocks connected in series: a first order system and a time delay. In fact, the gain, the time constant and the time delay of the system change linearly with the water that flows in the permutation chamber. The physical model of the electric water heater system was retched based in energy dynamic equations and validated with open loop data of the system in a similar way that was made in a previews study about modelling and controlling a gas water heater. The two different control algorithms explored are the adaptive proportional integral derivative (APID) and the Smith predictive control (SPC) based in the internal physical model control algorithm. The first approach has some problems dealing with the time constant and the time delay variations of the system. This solution can control the overshoot for all different water flows but the time constant of the close loop systems changes with the water flow. The APID does not deal well with water flow variations. The second approach is more adequate to control this kind of systems (first order system followed by a time delay that changes in time). The SPC loop is indicated for control time delay systems and with the à priori knowledge of the physical model we can achieve a very good control result. Finally, these two algorithms are applied in controlling the system and the results are compared using the mean square error criterion.