Bending moment characteristic analysis of utility-scale onshore wind turbine blades based on monitoring data

Bending moment is an important parameter in structural design of the wind turbine blades. The purpose of the present study is to accurately determine the actual bending moments on the blades of wind turbine in service and study the characteristics. It can be helpful to provide supports for the design load of wind turbine blades. For this purpose, a blade load monitoring system was developed and installed on a 2 MW onshore wind turbine to measure bending moments at the blade root. A simulation model which is consistent with the monitoring wind turbine was used to verify the availability of the system. Based on the monitored bending moments and operational conditions of the wind turbine, the characteristics and fatigue load of blade root bending moments were analyzed. Meanwhile, the relationship between bending moments of blade root and operational parameters was discussed. A thrust estimation method based on monitored bending moments of blade root was presented which will help to assess the loads on the tower and foundation of the wind turbine. At last, a calculation method of equivalent fatigue load based on wind speed-rotor speed joint distribution was established which will contribute to the fatigue design of blades.