Optimum settings for automatic controllers

Transactions of ASME 01/1993; DOI: 10.1115/1.2899060
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    ABSTRACT: The PID controller is widely used in process industries due to its functional simplicity and robustness. A common practice is to have a hierarchical structure with PID controllers at the lowest level while more advanced controllers are often placed at the higher level. It is important to have an efficient method for tuning the PID controller because of its widespread applications. Various tuning rules for PID controller are available but most of them are based on the simple first-order plus deadtime (FOPDT) model. In contrast, the tuning methods based on higher-order complex models are still very limited. In this paper, we present the construction of a PID controller tuning formula based on the second-order plus deadtime (SOPDT) model via the Multi-scale Control (MSC) approach. The effectiveness of this MSC-PID tuning formula is demonstrated using several examples and comparisons with some existing PID tuning methods.
    CHEMECA 2014, Perth, Western, Australia; 09/2014
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    Dataset: FSS 00Li
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    ABSTRACT: Decentralized PID control has been extensively used in process industry due to its functional simplicity. But designing an effective decentralized PID control system is very challenging because of process interactions and deadtimes, which often impose limitations on control performance. In practice, to alleviate the detrimental effect of process interactions on control performance, decoupling controllers are often incorporated into a decentralized control scheme. In many cases, these conventional decoupling controllers are not physically realizable or too complex for practical implementation. In this paper, we propose an alternative scheme to overcome the performance limitation imposed by process interactions. This new control scheme is extended from the SISO Multi-Scale Control scheme previously developed for nonminimum-phase processes. The salient feature of the new control scheme lies in its communicative structure enabling collaborative communication among all the sub-controllers in the system. This communicative structure serves the purpose of reducing the detrimental effect of process interactions leading to improved control performance and performance robustness. Extensive numerical study shows that the new control scheme is able to outperform some existing decentralized control schemes augmented with traditional decoupling controllers.
    Chemical Product and Process Modeling 09/2014;


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