Grid-connected kite generator system: Electrical variables control with MPPT

This paper presents a control scheme of a closed-orbit kite generator system (KGS), which is a wind-based energy producing system with a relaxation cycle. Such a system is divided into two main parts: a kite with its orientation mechanism and a power transformation system. Starting from a given closed orbit, the optimal tether's length rate variation (kite's tether radial velocity) and the optimal orbit's period are found. A trajectory-tracking control is developed for the kite's orientation. The power transformation system controls the kite's tether radial velocity and transforms the mechanical energy generated by the kite into electrical energy that can be added to the grid. A Matlab/simulink model of the KGS is employed to observe its behavior, and to insure the control of its mechanical and electrical variables. In order to improve the KGS's efficiency in case of changing wind speed, a maximum power point tracking (MPPT) algorithm is proposed.