Modeling the Risk of a Failed Wind Turbine Blade Impacting a Power Transmission Line

Abstract

Wind turbine installations are generally situated in proximity to power transmission lines that integrate generated power into the grid. Failure of a wind turbine that results in a blade or blade fragment thrown from the rotor can result in impact with a transmission line and lead to significant transmission line damage. The work reported here creates a mathematical model to assess the risk of this type of failure event occurring as a function of wind turbine characteristics and the relative position of the power transmission line. A comprehensive rotor blade flight dynamic simulation tool comprised of a rigid body representation with 6 degrees of freedom is used. The model generates full three dimensional motion of a failed wind turbine blade from release of the wind turbine blade at the point of failure to impact. Monte Carlo simulation is used to generate impact statistics including the probability that a failed wind turbine blade will impact a transmission line. A set of simulation results are generated for a nominal 1.5 MW wind turbine with a 50 m transmission height. Simulation results show that large blade fragments have relatively high transmission line impact probabilities for small offset distances while small blade fragments have overall lower impact probabilities but are spread over a larger offset distance range. Transmission line impact probability is also a strong function not only of the offset distance but also the orientation of the transmission line relative to the wind turbine and the atmospheric wind velocity vector.