Extending the RWM Stability Region by Optimal Feedback Control
J. Dalessio, E. Schuster, D. Humphreys, M. Walker, Y. In and J.S. Kim
IEEE Conference on Decision and Control
Cancun, Mexico, December 9-11, 2008
Abstract
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The stabilization of the resistive wall mode (RWM)
instability in the DIII-D tokamak is necessary to maintain conditions
for the plasma experiment. Stability has been achieved in
experiments using proportional/derivative (PD) gain controllers.
However, the stability range in terms of the mode growth
rate is limited. Employing an optimal feedback controller in
conjunction with a state estimator designed to reject sensor
colored noise, the stability region of the system is greatly
extended. Using experimental results, the power spectral density
of the measurement noise is used to model the colored noise as
a noise transfer function with a white noise input. The Linear
Quadratic Gaussian (LQG) control technique is applied and
results are compared to a traditional PD controller through
simulations.