Analysis and control of an hybrid system: a doubly-fed induction machine and a back-to-back converter

Abstract

This report describes the port interconnection of two subsystems: a power elec- tronics subsystem (a back-to-back AC/AC converter (B2B), coupled to a phase of the power grid), and an electromechanical subsystem (a doubly-fed induction ma- chine (DFIM), coupled mechanically to a flywheel and electrically to the power grid and to a local varying load). The B2B is a variable structure system (VSS), due to the presence of control-actuated switches; however, from a modelling and simula- tion, as well as a control-design, point of view, it is sensible to consider modulated transformers instead of the pairs of complementary switches. The port-Hamiltonian models of both subsystems are presented and, using a power-preserving interconnec- tion, the Hamiltonian description of the whole system is obtained. Using passivity- based controllers computed in the Hamiltonian formalism for both subsystems, a closed loop Hamiltonian system is presented; simulations are run to test the cor- rectness and e-ciency of the Hamiltonian network modelling approach used in this work.