Fig. 9 shows the simulation results of maximum, minimum, and mean values of the flapwise bending moment (My) at the blade root. The mean load values of the two periods were similar, but the deviations of the maximum and minimum values were significantly large in Period 2. Accordingly, we were able to confirm that Aclacinomycin A the changes in wind characteristics caused by the wake effect on turbulence intensity and wind shear gradient in Period 2 resulted in the high fluctuation of mechanical loads.
Fig. 9. Comparison of My bending moment at blade root in the each mean wind speed bin of two periods.Figure optionsDownload full-size imageDownload as PowerPoint slide
Table 6, Table 7, Table 8 and Table 9 displays DEL calculation results for the two periods and IEC classes compared with Period 1 data as reference values. Although there were differences in various load components, DEL increased by 30–50% in major load components in Period 2 (marked as bold in the tables). The flapwise bending moment on the blade (My at the blade root) in Period 2 increased by 30% from Period 1, which is higher than that of IEC class IIIB. The nacelle yawing moment on the hub (Mz at the hub stationary) and turn-over moment on the tower top and bottom (My at the tower top and bottom) in Period 2 also increased by about 50% and 40%, respectively. On the whole, the fatigue loads in Period 2 increased in almost all load components compared to that of Period 1.