Comparison of Control Strategies for Squirrel-Cage Induction Generator-based Wind Energy Conversion Systems

For induction motor speed control (IMSC) Stator-flux slip control (SFSC) is the simplest strategy due to its scheme with decoupled loops for stator flux dq components and that does not require internal current controllers, presenting good results with fast dynamics response. Nevertheless, direct torque control (DTC) is the most common strategy presenting good results including for the induction machine generating, but it presents a more complex scheme. In turn, Field-oriented control (FOC) is able to control the electromagnetic torque in an equivalent way to that of independent excitation dc machine and with similar performance of DTC, but with an even more complex scheme. This work proposes a comparison of these control strategies for maximum power point tracking (MPPT) of squirrel cage induction generator (SCIG)-based wind energy conversion systems (WECS). The obtained results demonstrated that the DTC and FOC techniques present better MPPT performance in comparison to SFSC, but this was not good enough to surpass the MPPT performance of SFSC plus its lowest total harmonic distortion (THD) and simplest scheme. For this reason, SFSC is the most suitable taking into consideration these performance indexes.