Autonomous operation of a doubly fed induction generator driven by a wind turbine

In this paper, an electrical generation system with variable speed and constant frequency (VSCF) to supply isolated loads is presented. This system is composed of a doubly fed induction generator (DFIG), providing energy to an autonomous grid. It is driven in the rotor by a static converter with operation in hypo and hyper synchronism. A permanent magnet synchronous machine (PMSM) connected to a wind turbine feeds this converter. This paper presents the general control system applied for linear loads. The DFIG is controlled by an internal control loop of rotor flux and an external control loop of output stator voltage. We present also the control of the PMSM and the DC bus of the converter. A power maximization algorithm determines the speed of the turbine that achieves maximum generated power.