Abstract: A joining device (8) for hybrid wind turbine towers (5) intended for the fixation of a metal portion (6) of a wind turbine tower (5) to a concrete portion (7) of said wind turbine (1) which comprises a metal body (9) having a generally tubular configuration that is suitable to be fixed to the metal portion (6) of the tower (5) which in use is adjacent to the concrete portion (7), and suitable for being at least partially embedded into said concrete portion (7), said metal body (9) being provided with a number of anchoring openings (11) adapted such that the material of the concrete portion (7) passes therethrough. A hybrid wind turbine tower (5) comprises such a joining device (8) provided between one metal portion (6) and one concrete portion (7).

Abstract: The present invention refers to a method of reducing torsional oscillations in the power train of a wind turbine in the event of grid loss. According to the method, after the grid loss, a braking torque is applied to the power train during a period of time and said period of time is determined as a function of the torsional resonance frequency of the power train.

Abstract: A method for determining the evolution of torque of at least one rotatable shaft and the resulting fatigue damage to different power train components is provided for design and/or maintenance operations in a wind turbine that comprises the steps of determining torque (Tg) at a high speed shaft of the power train; determining moment of inertia (Ig) at the high speed shaft; determining angular acceleration (?g) at the high speed shaft; and determining torque (Tr) at the low speed shaft of the power train through the formula Tr=(Tg?Ig ?g)·i. A rainflow-counting algorithm may be applied to the value of the torque (Tr) at the low speed shaft for determining the number of cycles at ranges of torque for every torque mean value.

Abstract: The method consists in determining at least one of wind turbine operating conditions or parameters related to pitch activity 116-119; determining if lubrication is needed depending on at least the operating conditions or the pitch activity parameters 116-119; and causing lubrication of the pitch blade bearing if lubrication is determined to be needed. Lubrication may consist in injecting grease during a period of time and causing the blades of the wind turbine to be rotated if necessary during grease injection. The device includes means for determining wind turbine operating conditions, means for determining parameters related to pitch activity, a wind turbine main control 100 for determining if lubrication is needed depending on operating conditions and pitch activity parameters 116-119, and means for causing lubrication of the pitch blade bearing if lubrication is needed.

Abstract: A joining device (8) for hybrid wind turbine towers (5) intended for the fixation of a metal portion (6) of a wind turbine tower (5) to a concrete portion (7) of said wind turbine (1) which comprises a metal body (9) having a generally tubular configuration that is suitable to be fixed to the metal portion (6) of the tower (5) which in use is adjacent to the concrete portion (7), and suitable for being at least partially embedded into said concrete portion (7), said metal body (9) being provided with a number of anchoring openings (11) adapted such that the material of the concrete portion (7) passes therethrough. A hybrid wind turbine tower (5) comprises such a joining device (8) provided between one metal portion (6) and one concrete portion (7).