Introduction

Abstract

The chapter presents the introduction to the subject of condition monitoring of wind turbine drivetrains. First, two types of wind turbine drivetrains, i.e. geared and gearless, are presented, but the drivetrain monitoring refers mostly to the geared design. Modern turbines are in vast majority designed as pitch controlled, i.e. changing a pitch angle of main rotor blades. Such a design feature has very important consequences for the vibration analysis due to continuous variability of the operational speed. The impact of differences between stall control and pitch control on the vibration behavior is presented. The main part of the chapter is the presentation of drivetrain components and vibration patterns (also called characteristic frequencies) they generate. This is fundamental knowledge if one wants to detect and identify the cause of a fault. Varying operational conditions are a key factor influencing vibrations of wind turbines. Due to inherent variability of the wind, both frequency and amplitude of vibration components change. The patterns of typical process parameters are presented on real data. The change in wind speed may cause an increase of vibration features, which certainly does not mean any deterioration of the technical state. Such an operating pattern must be taken into account when trying to diagnose a wind turbine. Vibration monitoring is the subject of this book, though it is only one out of many condition monitoring methods. The chapter briefly presents—apart from vibrations—other analysis methods: ultrasonic with Acoustic Emission, oil, electrical parameters and SCADA data.