Discernment of Static Eccentricity and Electrical Load Unbalance Currents through Space Vector Stray Flux in Permanent Magnet Synchronous Generator based Wind Turbines

The usage of permanent magnet synchronous generators (PMSGs) in wind turbines are getting increase due to their high efficacy and power densities. However, the electrical and mechanical asymmetries such as eccentricity and electrical load unbalanced currents can affect the dynamic operation condition in PMSGs. This paper proposes to detect and discriminate electrical load unbalance current faults and static eccentricity through space vector stray flux in surface mounted PMSGs based wind turbines. The 2D-finite element results shows that it is not possible to discern the static eccentricity and load unbalance current fault since both faults exhibits same pattern in current and stray flux spectra in PMSGs. The harmonic at +5f
s
in positive sequence stray flux can be used to discriminate static eccentricity and electrical load unbalance faults in PMSGs. The proposed method yields more precise and certain results compared to classical phase current and single point stray flux analysis.