Comparative Study on Performance Improvement of SPWM/THIPWM based DCMLI Grid Connected DFIG

Abstract

Multi-level voltage source converter is integrated in various fields in renewable energy power generation technologies such as wind and solar sources for applications that need higher voltage and higher power. In wind power generation market, doubly fed induction generator (DFIG) based on wind power generation is now the leading technology as they are economically feasible, they do offer a variable speed and efficient substitute to the fossil fuel. This paper proposes a DFIG based on a back to back diode clamped multilevel converter systems (DCMLI) fired comparatively by sinusoidal pulse width modulation (SPWM) and third harmonic injection pulse width modulation (THIPWM) techniques. By using these technologies, the DFIG performance is compared for different wind speeds under normal operation condition. The proposed approach shows that the DCMLI systems generate a near sinusoidal voltage with lower values in total harmonic distortion (THD) thus, upgrading the power quality that is produced by DFIG. Lastly, the variation of frequency of induced rotor voltage and the active power flow due to the wind speed changes when the rotor speed changes from super synchronous to sub synchronous speeds is investigated.