Impact of rotor solidity on wind turbine fatigue and extreme loads

For offshore wind turbines, as compared to onshore machines, acoustic emission regulations are usually less restrictive. Higher design tip speeds than would be acceptable on land are being employed. For a given rated power, this reduces rated torque and hence can save weight and cost in the drive train. In this context, within a generic study of load trends considering influences of
turbine scale, wind conditions and key turbine design parameters, it is of particular interest to better understand the impact of changes of rotor speed and solidity on the fatigue and extreme loads of typical upwind, three bladed, horizontal axis wind turbines. For this paper the focus is to investigate the dependence of fatigue and extreme loads on rotor speed taking account of necessary changes to blade design to preserve near optimum aerodynamic
performance. This work helps to understand the impact of rotor solidity on design driving loads, which may be fatigue or extreme.