| 摘要 |
<p>A method is present for controlling the pitch angle of the blades of a wind turbine rotor during an emergency stop process of the rotor from an operating state, wherein the method comprising the steps of
continuously determining a measure of the angular acceleration of the rotor, e.g. as the derivative of the angular speed of the rotor or from the an angular strain of the rotor shaft,
initiate pitching of the rotor blades and continue pitching until the time (t 2 ) where the determined angular acceleration of the rotor is substantially zero, and
resume pitching of the rotor blades at the end of a predetermined time period (t 3 - t 2 ), such as 2-5 seconds or about 0.5 time the period length of the first natural mode of the tower, after the time (t 2 ) where the determined angular acceleration of the rotor was substantially zero wherein said method further comprises the steps of
opening an electrical switch in the electric connection between an emergency power supply and drive means for driving the pitching of the rotor blades at the time (t 2 ) when the determined angular acceleration of the rotor is substantially zero, and
closing said electrical switch said predetermined time period (t 3 - t 2 ) after the time (t 2 ) where the determined angular acceleration of the rotor was substantially zero.</p> |
