Variable-structure control using the idea of a fictitious set point temperature tracking control of a batch reactor process

This paper shows how a control strategy using a 'fictitious' set point can be applied to the tracking control problem of a batch reactor process, and demonstrates that excellent control results have been obtained. In this pro cess, the reactor temperature is required to be raised at a fixed rate from the start-up to the desired temperature, and to be kept at that temperatur e. PID control was previously used to achieve this objective, but the react or temperature showed frequent variations near the desired temperature, and heating steam and cooling water were wasted in this type of control. Conve ntional variable-structure control is then considered to avoid such variati ons. However, a computer simulation shows that the tracking control respons e cannot be improved by this means. To reduce the frequent temperature vari ations and the waste of energy, a new control strategy is applied to this p rocess, following computer simulations. The experimental results are that t his method is quite effective as compared with PID control and conventional VSC laws, and that the temperature variation and the consumption of both s team and cooling water were decreased by 50 and 45%, respectively. (C) 1998 Elsevier Science Ltd. AII rights reserved.