An implementation of field oriented controlled SCIG for variable speed wind turbine

This paper presents a grid connected squirrel cage induction generator (SCIG) driven by a back-to-back converter in variable speed wind turbine system. The back-to-back converter is composed of the machine side converter coupling to the line side connected together via DC bus capacitor. Both converters used the vector control and decoupling control in the d-, q-axis reference frame. The control objectives of the machine side converter are to optimize the energy capture from the wind and supply the excitation flux to the SCIG whereas the objectives of line side converter are to deliver the energy from the machine side to the utility grid and to regulate the DC bus voltage. The experiments in this paper are tested with a 5.5 kW SCIG coupled with a 7.5 kW wind turbine simulator. The experimental results show the high-quality control performance during dynamic and steady state conditions. Moreover for the grid side, the line current has low total harmonic distortion (THD) and a reactive power can be controlled at a unity power factor.