Indirect field orientation control of self-excited induction generator for wind energy conversion system

This paper presents the analysis, design and simulation of the indirect field orientation control (IFOC) of self-excited induction generator (SEIG) for wind energy conversion system (WECS). Also, the paper describes the dynamic performance of the SEIG driven from a wind turbine. The performance includes d-q axes dynamic stator voltages, stator currents, capacitor currents, load currents and rotor fluxes as well as the stator angular frequency, power and the electromagnetic torque of the SEIG. During voltage build up of the IG, the variation of the magnetizing inductance is considered. The SEIG feeds a current regulated pulse-width modulation (CRPWM) converter. The voltage build up process and DC-link voltage control are accomplished utilizing the IFOC of the SEIG. The aim of the CRPWM converter is to regulate the DC-Iink voltage at a constant value where the speed of the IG is varied. The converter receives the AC power from the IG and converts it to DC power with regulated DC voltage to supply batteries and/or DC loads. Based on the IG d-q axes dynamic model in the synchronous reference frame at field orientation, high performance synchronous proportional plus integral (PI) d-q axes current controllers with satisfactory performance are designed and analyzed. Utilizing these current controllers and IFOC a fast dynamic response and low current harmonic distortion are attained. Simulation results are presented to illustrate the effectiveness of the proposed control scheme. In the simulation results, the d-q axes current controllers and DC-Iink voltage controller give prominent dynamic response in command tracking and load regulation characteristics.