PID Controller Design Directly from Plant Data for Single-Loop and Multi-Loop Systems

• Main Authors: Wan-Ling Tseng, 曾莞玲
• Other Authors: 鄭智成
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/7bs5ww

碩士 === 國立臺北科技大學 === 化學工程研究所 === 100 === PID controllers are the most widely used controllers in the chemical process industries, and various model-based PID design methods can be found in the literature. A major drawback of the model-based PID design is that the effectiveness of these methods would degrade for higher-order process dynamics owing to the inevitable modeling error. Consequently, it is an attractive alternative to design PID controller directly based on a set of process input and output data without resorting to a process model. This study proposes the PID controller design directly based on process data available from plant test. The PID design for single-loop control systems is first discussed, and then the method is extended to multi-loop control systems. The proposed direct PID controller design approximately solves a model-reference problem. The design goal for single-loop control systems is to obtain PID parameters such that the feedback control system behaves as closely as possible to the prespecified reference model. The robustness consideration is included in the selection of the reference model. Multi-loop control systems can be decomposed into a number of equivalent single loops by an effective open-loop process. Therefore, the design goal for multi-loop control systems is to obtain PID parameters such that each equivalent single loop behaves as closely as possible to the prespecified reference model. The selection of the reference model for each equivalent single loop considers an appropriate tradeoff between the bandwidth of main loop and the magnitude of interaction loops. The optimization problems pertaining to the proposed design are derived, and the associated design issues are addressed. Extensive simulation results show that the proposed data-based PID design gives better or comparable control performance than those attained by the model-based PID designs. Consequently, the proposed design is an attractive alternative to the model-based PID design methods and has considerable potential in practical applications.