Profile control simulations and experiments on TCV: a controller test environment and results using a model-based predictive controller

Maljaars, E.; Felici, F.; Blanken, T.C.; Galperti, C.; Sauter, O.; Baar, M.R. de; Carpanese, F.; Goodman, T. P.; Kim, D.; Kim, S.H.; Kong, M.; Mavkov, Bojan; Merle, A.; Moret, J.M.; Nouailletas, R.; Scheffer, M.; Teplukhina, A.; Vu, N. M. T.

doi:10.1088/1741-4326/aa8c48

Cited by 33 publications

(37 citation statements)

References 46 publications

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“…Using the first version of the system, with generic controllers and a preliminary actuator manager, RT integrated control of NTMs, β and model-estimated q profiles has been demonstrated on TCV. The details of various β and q profile controllers have been presented in references [23][24][25], and here we only concentrate on the generic NTM controller. As shown in figure 21 and preliminarily presented in reference [26], three EC launchers (L1, L4 and L6) are used to perform the three control tasks.…”

Section: Rt Integrated Control Of Ntms β and Model-estimated Q Profimentioning

confidence: 99%

Control of neoclassical tearing modes and integrated multi-actuator plasma control on TCV

et al. 2019

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The control of 2/1 neoclassical tearing modes (NTMs) with electron cyclotron (EC) waves has been studied both experimentally and numerically on TCV. Dynamic evolutions of NTMs along with time-varying deposition locations of the control beam have been studied in detail. The prevention of NTMs by means of preemptive EC (i.e. the control beam is switched on before the mode onset) has also been explored. A small sinusoidal sweeping with full amplitude of 0.07 (normalized to the minor radius) has been added to the control beam in two of the experiments to facilitate the comparison between NTM stabilization and prevention. It is shown that the prevention of NTMs is more efficient than NTM stabilization in terms of the minimum EC power required. Interpretative simulations with the Modified Rutherford Equation (MRE) have been performed to better quantify various effects, with coefficients well defined by dedicated experiments. Specifically, in order to obtain more insight on the dominant dependencies, a simple ad-hoc analytical model has been proposed to evaluate the time-varying classical stability index ∆ in the test discharges, based on the ∆ -triggered nature of these 2/1 NTMs. This allows simulating well the entire island width evolution with the MRE, starting from zero width and including both NTM stabilization and prevention cases for the first time. The exploration of NTM physics and control has facilitated the development of an NTM controller that is independent of the particular features of TCV and has been included in a generic plasma control system (PCS) framework. Integrated control of 2/1 NTMs, plasma β (the ratio of plasma pressure to magnetic pressure) and model-estimated safety factor q profiles has been demonstrated on TCV.

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Section: Rt Integrated Control Of Ntms β and Model-estimated Q Profimentioning

confidence: 99%

Control of neoclassical tearing modes and integrated multi-actuator plasma control on TCV

et al. 2019

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“…In other words, J ι (t) is integral of weighted ι tracking error, where the spatial weighting W (ρ) is defined in [19] and is used to highlight the part of the region of interest to measure the performance of the feedback control. In these control scenarios more emphasis is given to the region closer to the plasma centre.…”

Section: Performance Criterionmentioning

confidence: 99%

“…After the extensive tests of the control algorithm using the RAPTOR simulator, the control algorithm is transferred and implemented in the TCV control system. The control environment [19] permits the MATLAB software for the controller to be used directly in the experiments. The RAPTOR code is incorporated as an observer in the TCV control environment, which provides the essential real-time estimates of the T e and Ψ profiles in several ρ-grid points.…”

Section: Tcv Experimentsmentioning

confidence: 99%

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Experimental validation of a Lyapunov-based controller for the plasma safety factor and plasma pressure in the TCV tokamak

Mavkov¹,

Witrant²,

Prieur³

et al. 2018

Nucl. Fusion

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In this paper model-based closed-loop algorithms are derived for distributed control of the inverse of the safety factor profile and the plasma pressure parameter β of the TCV tokamak. The simultaneous control of the two plasma quantities is performed by combining two different control methods. The control design of the plasma safety factor is based on an infinite-dimensional setting using Lyapunov analysis for partial differential equations, while the control of the plasma pressure parameter is designed using control techniques for singleinput and single-output systems. The performance and robustness of the proposed controller is analyzed in simulations using the fast plasma transport simulator RAPTOR. The control is then implemented and tested in experiments in TCV Lmode discharges using the RAPTOR model predicted estimates for the q-profile. The distributed control in TCV is performed using one co-current and one countercurrent Electron Cyclotron Heating actuation.

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“…This enabled several applications of MPC in magnetic control for tokamaks and RFPs. Maaljars et al [65,66] presented MPC control of the plasma pressure and safety factor profile for ITER and TCV using the RAPTOR code; Wehner et al [67] uses MPC for control of plasma safety factor profile for DIII-D. Gerkšič et al [68,69] implemented MPC plasma current and shape control for ITER using a dual fast gradient method (FGM) QP solver [63]. Gerkšič et al [70] used explicit MPC for VS of the n = 0 mode for ITER, which does not require on-line optimization because a parametric solution is computed in advance, but this is suitable only for lowdimensional control problems.…”

Section: Introductionmentioning

confidence: 99%

Model predictive control of resistive wall mode for ITER

Gerkšič

Pregelj

Ariola

2020

Fusion Engineering and Design

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Active feedback stabilization of the dominant resistive wall mode (RWM) for an ITER H-mode scenario at high plasma pressure using infinite-horizon model predictive control (MPC) is presented. The MPC approach is closely-related to linear-quadratic-Gaussian (LQG) control, improving the performance in the vicinity of constraints. The control-oriented model for MPC is obtained with model reduction from a high-dimensional model produced by CarMa code. Due to the limited time for on-line optimization, a suitable MPC formulation considering only input (coil voltage) constraints is chosen, and the primal fast gradient method is used for solving the associated quadratic programming problem. The performance is evaluated in simulation in comparison to LQG control. Sensitivity to noise, robustness to changes of unstable RWM dynamics, and size of the domain of attraction of the initial conditions of the unstable modes are examined.

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Profile control simulations and experiments on TCV: a controller test environment and results using a model-based predictive controller

Cited by 33 publications

References 46 publications

Control of neoclassical tearing modes and integrated multi-actuator plasma control on TCV

Control of neoclassical tearing modes and integrated multi-actuator plasma control on TCV

Experimental validation of a Lyapunov-based controller for the plasma safety factor and plasma pressure in the TCV tokamak

Model predictive control of resistive wall mode for ITER

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