Robust control design for the plasma horizontal position control on J-TEXT Tokamak

It is extremely important for tokamak to control the plasma position during routine discharge. However, the model of plasma in tokamak usually contains much of the uncertainty, such as structured uncertainties and unmodeled dynamics. Compared with the traditional PID control approach, robust control theory is more suitable to handle this problem. In the paper, we propose a H∞ robust control scheme to control the horizontal position of plasma during the flat-top phase of discharge on Joint Texas Experimental Tokamak (J-TEXT) tokamak. First, the model of our plant for plasma horizontal position control is obtained from the position equilibrium equations. Then the H∞ robust control framework is used to synthesize the controller. Based on this, an H∞ controller is designed to minimize the regulation/tracking error. Finally, a comparison study is conducted between the optimized H∞ robust controller and the traditional PID controller in simulations. The simulation results of the H∞ robust controller show a significant improvement of the performance with respect to those obtained with traditional PID controller, which is currently used on our machine.