Continuous, saturation, and discontinuous tokamak plasma vertical position control systems

• Published in: Fusion engineering and design 2016-10, Vol.108, p.35-47
• Main Authors: Mitrishkin, Yuri V., Pavlova, Evgeniia A., Kuznetsov, Evgenii A., Gaydamaka, Kirill I.
• Format: Article
• Language: English
• Subjects: Feedback control; Feedback stabilization; Frequency-response methods; Linear systems; Nonlinear oscillations; Nonlinear systems; Parametric optimization; Pole placement problems; Process control; Robust stability; Synthesis problems; System structure simplification
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2016.04.026

[Display omitted] •Robust new linear state feedback control system for tokamak plasma vertical position.•Plasma vertical position relay control system with voltage inverter in sliding mode.•Design of full models of multiphase rectifier and voltage inverter.•First-order unit approximation of full multiphase rectifier model with high accuracy.•Wider range of unstable plant parameters of stable control system with multiphase rectifier. This paper is devoted to the design and comparison of unstable plasma vertical position control systems in the T-15 tokamak with the application of two types of actuators: a multiphase thyristor rectifier and a transistor voltage inverter. An unstable dynamic element obtained by the identification of plasma-physical DINA code was used as the plasma model. The simplest static feedback state space control law was synthesized as a linear combination of signals accessible to physical measurements, namely the plasma vertical displacement, the current, and the voltage in a horizontal field coil, to solve the pole placement problem for a closed-loop system. Only one system distinctive parameter was used to optimize the performance of the feedback system, viz., a multiple real pole. A first-order inertial unit was used as the rectifier model in the feedback. A system with a complete rectifier model was investigated as well. A system with the voltage inverter model and static linear controller was brought into a sliding mode. As this takes place, real time delays were taken into account in the discontinuous voltage inverter model. The comparison of the linear and sliding mode systems showed that the linear system enjoyed an essentially wider range of the plant model parameters where the feedback system was stable.