Variable speed induction generator connected to AC grid using AC-DC-AC structures controlled by LQ current regulators with integral action

This paper presents a discrete control system based on Linear Quadratic Regulator with integral action for variable speed generation system connected to AC grid using an AC-DC-AC converter with VSI structure. The proposal consists basically in two LQ current regulators with integral action for the control of the flux of active and reactive power in the AC generator and AC line in order to obtain a good dynamic performance, a stable operation, robustness to disturbance and parameter variations, and the minimization of the power losses. An outer feedback loop with a PI controller and a feed-forward action realizes the voltage control in the DC bus. A little variable speed asynchronous generation system connected to AC grid using a AC-DC-AC converter with VSI structure is experimentally implemented in order to verify the response of the proposed control scheme, which presents a satisfactory dynamic performance.