Vector Control of a Variable Speed Doubly-Fed Induction Machine for Wind Generation Systems

Abstract

SummaryControl techniques suitable for a doubly fed induction generator applied to a wind generation system are presented. A Scherbius scheme using two back-to-back voltage-fed current-regulated inverters in the rotor circuit is employed allowing subsynchronous and supersynchronous operation with low distortion currents. A vector control scheme using a reference frame oriented along the stator flux vector is used for the machine. This leads to independent control of the electrical torque and the rotor excitation current. A vector scheme aligned with the stator voltage vector is used to control the stator-side converter; this gives independent control over the active and reactive power flow between the supply and the stator-side converter. The control strategies are tested with the machine working as a variable speed constant frequency generator driven by a wind turbine emulator. Two approaches for optimum speed tracking of the wind turbine are implemented and experimental results for a prototype system ar...