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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Evaluation of adaptive PID controls for a resistive system of heating water

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Author(s):
Maria Isabel Berto [1] ; Fabiana Rodrigues de Sá [2] ; Vivaldo Silveira Jr. [3]
Total Authors: 3
Affiliation:
[1] Universidade Estadual de Campinas. Depto. Engenharia de Alimentos. Laboratório de Automação e Controle de Processos de Alimentos
[2] Universidade Estadual de Campinas. Depto. Engenharia de Alimentos. Laboratório de Automação e Controle de Processos de Alimentos
[3] Universidade Estadual de Campinas. Depto. Engenharia de Alimentos. Laboratório de Automação e Controle de Processos de Alimentos
Total Affiliations: 3
Document type: Journal article
Source: FOOD SCIENCE AND TECHNOLOGY; v. 24, n. 3, p. 478-485, 2004-09-00.
Abstract

The aim of this work is to implement a conventional PID/SISO feedback control to obtain a fine adjustment of the water inlet temperature at a pasteurization process. For that, a resistance of 2500 Watts and a Pt100 to measure the temperature were installed in the water inlet line of the pasteurizer heating section. As the water temperature behavior according to the same step change on the potency of the resistance depends on the working flow rate, a single controller was designed to keep this temperature at its desirable set-point, for the water flow rate, within the range of 300 to 700L/h. Three different tunings for the PID were tested: the first consisted on the implementation of a function for the calculation of the PID parameters fitted to individual values obtained from each flow rate, according to process reaction curve methodology; the second consisted on using the PID parameters calculated as the average of these individual values; at the third tuning, an adaptive function fitted with the individual parameters obtained with Aström & Hägglund methodology was used. The performance evaluation of the configured PID controllers was carried out by comparing the error index values, obtained after disturbances in the water flow rate in the closed loop system. The error indexes calculated after step changes in the water flow rate were used to evaluate the tunings. The results have shown that the third tuning, called "Bang Bang" presented minor oscillations and smaller error indexes compared to the other two methods. (AU)