Page 1 of 5 THE CORRELATION BETWEEN WIND TURBINE TURBULENCE AND PITCH FAILURE Peter TAVNER, Yingning QIU, Athanasios KOROGIANNOS, Yanhui FENG Energy Group, School of Engineering and Computing Sciences, Durham University, UK. Corresponding author:peter.tavner@durham.ac.uk 1. INTRODUCTION Quantitative studies on public survey of LWK database and WMEP have shown similar failure rate and downtime of different wind turbine sub-assemblies [1,2,3] as shown in figure 1. It clearly shows that the rotor blades, rotor hub and pitch mechnism are one of the important aspects to affect the wind turbine unreliability. In order to reduce the wind turbines’ failure rate and then the down time to improve the wind turbine reliability, it is important to understand the failure mode and the corresponding root cause. Clear evidence has been shown in [4] that weather and location affects the failure rate of a wind turbine which indicates important considerstions for both wind turbine design and wind farm location decision. This paper further investigates stochastic wind fluctuations, named wind turbulence, and their effects on pitch mechanism failures. Figure 1. Failure/turbine/year and Downtime from 2 European WT Surveys over 13 years. There are numbers of researches about wind turbulence05-10], which shows the wind turbine control strategy is affected by wind fluctuation and so does the power curve. To investigate wind turbulence it is necessary to take accurate spatial and temporal wind speed measurements with high frequency sampling rate, as shown in Figure 2. It shows that the intermitten distribution of wind speed variation compared with a Gaussian distribution. It implies a high probability of wind fluctuation events with considerable magnitude deviation rom mean wind speed. This occasional wind gust will introduce non-cyclic fatige loads to the wind turbine components that are exposed to aerodynamic effects, such as the blades and pitch mechanism. Drive Train Generator Gearbox Rotor Blades Mechanical Brake Rotor Hub Yaw System Hydraulic System Other Electrical Control Electrical System LWK Failure Rate, approx 5800 Turbine Years WMEP Failure Rate, approx 15400 Turbine Years LWK Downtime, approx 5800 Turbine Years WMEP Downtime, approx 15400 Turbine Years 1 0.75 0.5 0.25 0 2 4 6 8 10 12 14 Failure/turbine/year Downtime per failure (days)