Condition monitoring of permanent magnet synchronous generator for wind turbine applications

Wind energy has gained a considerable attention from industries and academia to increase the reliability and availability of wind turbines (WTs) and, consequently, to reduce wind energy cost. With this attention has come investments and new technologies from WT manufacturers as industrial solutions. Among these technologies the new arrivals, the variable speed generation systems based on permanent magnet synchronous generators (PMSGs) with full-scale power converters are an emerging and promising technology. Better designs of the WT components is of course one answer to the solution of this problem; the other is condition monitoring of the WT systems. This allows to reduce maintenance cost, hardware damaging and unscheduled downtime. In this context, this paper investigates the possibility to detect mechanical faults by analysing the electrical signals with the aim of improving the reliability of WTs based on PMSGs. Rotor eccentricity is used as an illustrative example to describe how the fault signature frequencies may occur in PMSG current signals, and potentially how they may deviate from a healthy state, firstly under steady state, constant speed test operation and secondly under transient, variable speed conditions. Simulation results yield valuable information for condition monitoring and effective algorithm development for fault detection.