Patent ID: 11939959
Assignee: VESTAS WIND SYSTEMS A/S
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  Y | IPC F

Claim 9:
10. The method of claim 9, wherein the safety controller executes a stopping process arranged to pitch the one or more blades individually at a number of pre-set constant pitch rates including a first pitch rate and a second pitch rate lower than the first pitch rate, and wherein the safety controller is further arranged to:
access desired pitch angles of the stopping process;
add an envelope band to the desired pitch angles by adding a positive value and a negative value thereby defining an upper band value and a lower band value; and
wherein a stop controller is arranged to:
move each pitch adjustable rotor blade at a selected pitch rate among the number of pre-set pitch rates until the pitch angle signal is outside a pitch angle value defined by the envelope band;
if the stored pitch angle signal is larger than the upper band value, change the selected pitch rate to a lower pitch rate among the number of pre-set pitch rates; and
if the stored pitch angle signal is smaller than the lower band value, change the selected pitch rate to a higher pitch rate among the number of pre-set pitch rates.