Harmonic suppression and performance improvement for a small-scale grid-tied wind turbine using proportional-resonant controllers

Small-scale wind turbines installed at the end of a distribution feeder are beneficial in reducing fossil fuel use as well as power transmission loss. However, wind turbines are inherently noisy due to the electro-mechanical oscillation attributed to the harmonic distortion. To eliminate the low-order harmonic distortion and refine the power quality without purchasing additional equipment, two control loops with power factor correction and selective harmonic compensation capabilities are proposed for the inverters tapped at the wind turbine generator side and the grid side. The capacity used for selective harmonic compensation is removable with escalating wind power in the case of the over-loading condition. A proportional-resonant controller with the advantages of easy implementation and high immunity to disturbance was adopted for the inverters to achieve quick and tight regulation in current response. An algebraic algorithm based on the pole-zero cancellation technique is proposed to simplify the proportional-resonant controller design and can be used in fundamental and harmonic current control for the stator-side and grid-side inverters. The proposed strategy was assessed and validated experimentally using a 1.5kW vertical axis wind turbine (VAWT)-driven permanent magnet synchronous generator (PMSG) under various wind speeds.