Comparison of Electrical and Vibration Analysis Methods for Mechanical Fault Monitoring in Wind Turbine Drivetrains

Abstract

Mechanical faults occurring in drivetrains are traditionally monitored through vibration analysis and, more rarely, by analysing electrical quantities measured on the electromechanical system involved. However, a monitoring method that is able to take into account all of the information contained in three-phase electrical quantities was recently proposed. The goal of this paper is to compare this threephase electrical approach with the usual vibration-based method in terms of its capability to detect mechanical faults in drivetrains. In this context, a 2 MW geared wind turbine operating in an industrial wind farm was equipped with accelerometers near the main bearing and electrical sensors on the stator of the electrical generator for several months. During this period, an important mechanical fault occurred in the main bearing of the system. The evolution of the fault indicators computed by the two previous approaches were compared throughout this period of time. All of the indicators behaved similarly and showed the development of an inner bearing fault in the main bearing. This demonstrated that a mechanical fault occurring in a drivetrain can be monitored and detected by analysing electrical quantities, even if the fault is located some distance from the electrical generator.