On-line Model Structure Selection for Estimation of Plasma Boundary in a Tokamak

12th European Workshop on Advanced Control and Diagnosis

Škvára, Vít^1 ; Šmídl, Václav^1 ; Urban, Jakub^2

Institute of Information Theory and Automation, Prague, Czech Republic^1

Institute of Plasma Physics, Prague, Czech Republic^2

关键词: Boundary estimation;    Induction coils;    Least squares problems;    Least-squares estimator;    Online modeling;    Plasma boundary;    Plasma fields;    Simple linear regression;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/659/1/012010/pdf
DOI  :  10.1088/1742-6596/659/1/012010

来源: IOP

【 摘 要 】

Control of the plasma field in the tokamak requires reliable estimation of the plasma boundary. The plasma boundary is given by a complex mathematical model and the only available measurements are responses of induction coils around the plasma. For the purpose of boundary estimation the model can be reduced to simple linear regression with potentially infinitely many elements. The number of elements must be selected manually and this choice significantly influences the resulting shape. In this paper, we investigate the use of formal model structure estimation techniques for the problem. Specifically, we formulate a sparse least squares estimator using the automatic relevance principle. The resulting algorithm is a repetitive evaluation of the least squares problem which could be computed in real time. Performance of the resulting algorithm is illustrated on simulated data and evaluated with respect to a more detailed and computationally costly model FREEBIE.