Soft Sensor for Inputs and Parameters Using Nonlinear Singular State Observer in Chemical Processes

doi:10.1016/S1004-9541(13)60570-4

Abstract

Abstract: Chemical processes are usually nonlinear singular systems. In this study, a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes, which are augmented as state variables. Based on the observability of the singular system, this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters. When the observability is satisfied, the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer. The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation. With the catalyst circulation rate as the only unknown input without model error, one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst circulation rate. However, when uncertain model parameters also exist, additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes.

Key words: soft sensor, state observer, nonlinear singular system, unknown inputs, uncertain model parameters, riser reactor of fluid catalytic cracking unit

摘要： Chemical processes are usually nonlinear singular systems. In this study, a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes, which are augmented as state variables. Based on the observability of the singular system, this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters. When the observability is satisfied, the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer. The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation. With the catalyst circulation rate as the only unknown input without model error, one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst circulation rate. However, when uncertain model parameters also exist, additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes.

关键词: soft sensor, state observer, nonlinear singular system, unknown inputs, uncertain model parameters, riser reactor of fluid catalytic cracking unit

XU Feng, WANG Yeye, LUO Xionglin. Soft Sensor for Inputs and Parameters Using Nonlinear Singular State Observer in Chemical Processes[J]. Chin.J.Chem.Eng., 2013, 21(9): 1038-1047.

许锋, 汪晔晔, 罗雄麟. Soft Sensor for Inputs and Parameters Using Nonlinear Singular State Observer in Chemical Processes[J]. Chinese Journal of Chemical Engineering, 2013, 21(9): 1038-1047.

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