A review of harmonic elimination techniques in grid connected doubly fed induction generator based wind energy system

Wind energy is one of the developed forms of renewable energy which has seen a rapid increase in its demand by the utilities. The Doubly Fed Induction Generator (DFIG) based variable-speed wind turbine with pitch control scheme is the most popular wind power generator in the wind power industry. In this generator, a stator is directly connected to the grid, whereas rotor is connected to the grid via back-to-back power electronics converters. Due to this nonlinear devices connected to the grid, quality of power deteriorates. It draws a significant amount of harmonic currents. This leads to the generation of voltage harmonics in the grid due to the impedance of the transmission lines. A number of publications report related to the improvement of power quality, specifically, the harmonic elimination techniques for a wind energy conversion system. A critical assessment is required for making a choice on an exact harmonic elimination technique for a specific case. That is why an exhaustive review of all those techniques is very relevant. Only a countable number of attempts have been made in this regard. This paper emphasizes on various available harmonic mitigation techniques. This ensures the safeguarding of grid connected doubly fed induction generators from the harmful effects of harmonics. Thus, it helps in maintaining standards related to power quality.