Influence of supply harmonic voltages on DFIG stator current and power spectrum

This paper investigates the impact of supply harmonic voltages on DFIG stator current and power spectra. The influence of individual higher order supply harmonics on DFIG stator current and on total instantaneous power spectral content is investigated using a time-stepped circuit model. The observed effects are identified in experimental data obtained from a laboratory test rig. A set of analytical expressions that define the spectral characteristics of DFIG power and current signals is also presented. This work demonstrates that supply harmonic voltages have a significant impact on DFIG harmonic emissions and result in a range of well defined and calculable slip-dependant interharmonic current and power frequency components.

I. Introduction

Wind energy remains one of the fastest growing renewable sources of electricity generation today. With this significant advance of wind power generation come new challenges in integration of power generated from wind into existing electrical grids. One of a number of power quality requirements that need to be satisfied for a grid connected wind turbine concerns the harmonic content of the generated current [1]–[3].