Incremental multivariable predictive functional control and its application in a gas fractionation unit
来源期刊：中南大学学报(英文版)2015年第12期
论文作者：SHI Hui-yuan SU Cheng-li CAO Jiang-tao LI Ping SONG Ying-li LI Ning-bo
文章页码：4653 - 4668
Key words：gas fractionation unit; multivariable process; incremental predictive functional control
Abstract: The control of gas fractionation unit (GFU) in petroleum industry is very difficult due to multivariable characteristics and a large time delay. PID controllers are still applied in most industry processes. However, the traditional PID control has been proven not sufficient and capable for this particular petro-chemical process. In this work, an incremental multivariable predictive functional control (IMPFC) algorithm was proposed with less online computation, great precision and fast response. An incremental transfer function matrix model was set up through the step-response data, and predictive outputs were deduced with the theory of single-value optimization. The results show that the method can optimize the incremental control variable and reject the constraint of the incremental control variable with the positional predictive functional control algorithm, and thereby making the control variable smoother. The predictive output error and future set-point were approximated by a polynomial, which can overcome the problem under the model mismatch and make the predictive outputs track the reference trajectory. Then, the design of incremental multivariable predictive functional control was studied. Simulation and application results show that the proposed control strategy is effective and feasible to improve control performance and robustness of process.
SHI Hui-yuan(施惠元), SU Cheng-li(苏成利), CAO Jiang-tao(曹江涛), LI Ping(李平), SONG Ying-li(宋英莉), LI Ning-bo(李宁波)
(School of Information and Control Engineering, Liaoning Shihua University, Fushun 113001, China)
Abstract:The control of gas fractionation unit (GFU) in petroleum industry is very difficult due to multivariable characteristics and a large time delay. PID controllers are still applied in most industry processes. However, the traditional PID control has been proven not sufficient and capable for this particular petro-chemical process. In this work, an incremental multivariable predictive functional control (IMPFC) algorithm was proposed with less online computation, great precision and fast response. An incremental transfer function matrix model was set up through the step-response data, and predictive outputs were deduced with the theory of single-value optimization. The results show that the method can optimize the incremental control variable and reject the constraint of the incremental control variable with the positional predictive functional control algorithm, and thereby making the control variable smoother. The predictive output error and future set-point were approximated by a polynomial, which can overcome the problem under the model mismatch and make the predictive outputs track the reference trajectory. Then, the design of incremental multivariable predictive functional control was studied. Simulation and application results show that the proposed control strategy is effective and feasible to improve control performance and robustness of process.
Key words:gas fractionation unit; multivariable process; incremental predictive functional control
