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Control System Performance Assessment Based On Generalized Minimum Variance Benchmark

Posted on:2011-01-22Degree:MasterType:Thesis
Country:ChinaCandidate:H B WangFull Text:PDF
GTID:2178330338477847Subject:Systems Engineering
Abstract/Summary:PDF Full Text Request
There are tens of thousands of control loops with different structure in modern industrial processes, such as single loop control, cascade control, multivariate control and so on. Many controllers always perform well at first and then deteriorate after a period of time. Eventually, That may lead to lower product quality,higher operating costs or even security problems. Therefore control performance assessment (CPA) is really significant and worthy.Minimum Variance (MV) benchmark is widely used in early CPA researches. However, Minimum Variance Control (MVC) often results in high gain, wide bandwidth and unrealistically large control signal variations, and MVC is scarcely used in practice. Thus MV benchmark is not suitable for general control systems. In this paper, in order to roundly reflect control performance information, Generalized Minimum Variance (GMV) Benchmark was adopted for CPA research, which was first proposed by Grimble M.J. The main research results are as follows:(1) A long-divide algorithm was given to find out feedback time-invariable term for GMV benchmark and the GMV controller, with illustration examples to show the effectiveness.(2) Cascade control is widely used in process industry. In this paper, the GMV benchmark for cascade control system CPA was derived. Simulation examples showed that GMV benchmark is more sensitive than MV for manipulating variable variations.(3) Single-loop and cascade control experiments were given based on pilot equipment. CPA results coincided with the experiments.The study shows that GMV Benchmark takes constraints and punishments of control movements into consideration, and roundly reflects the control information. Therefore we believe that GMV is realistic and will play an important role for CPA in the future.
Keywords/Search Tags:Minimum Variance (MV), Generalized Minimum Variance (GMV), PID control, Cascade control, Multivariable control, DCS
PDF Full Text Request
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