| 摘要 |
PROBLEM TO BE SOLVED: To secure a stand-by form in which a rotor and a blade leading edge streams to a lee side even if yaw drive means does not function at the time of a storm and reduce a storm time design load of the wind mill by the stand-by form in an up-wind type horizontal axis windmill. SOLUTION: The horizontal axis windmill makes all blades 4a-4c to feather when wind speed exceeds cut out wind speed (Fig. 1(a)). Then, a yaw brake is controlled to a predetermined brake value permitting yaw rotation of a nacelle 2 by wind power and angles of one of blades 4a is changed from feather to flat side (Fig. 1(b)). When about 30 degree of yaw angle displacement of the nacelle 2 is generated, one of the blades 4a is returned to feather, then all blades 4a-4c are retained in the feather condition until recovery of an operation mode (Fig. 1(c)→(d)). In the process mentioned above, the nacelle 2 rotate in a yaw direction and the rotor is arranged in the lee side of a tower 1 and trailing edges of all blades 4a-4c is oriented to a weather side (Fig. 1 (e)). COPYRIGHT: (C)2007,JPO&INPIT
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