Electrical pitch control system and a method for operating at least one rotor blade and use of the system for performing the method

An electrical pitch control system for controlling at least one rotor blade for a wind turbine, said wind turbine comprising:

• a nacelle, as well as a hub both arranged on a top of a tower, said hub is adapted to rotate around an axis, and at least one rotor blade is pivotable mounted on the hub,
• said system comprising at least one electrical pitch drive system, each drive system is connected to a rotor blade and an electrical pitch motor;
• the electrical pitch drive system(s) and the motor(s) are placed in the hub,
• said electrical pitch drive system(s) is/are adapted to communicate with units comprising the motor(s) for pitching the rotor blade it is attached to and in accordance with inputs registered from a first sensor and a second sensor
• and said electrical pitch control system further comprises at least one gyroscope placed in the hub, each electrical pitch drive system(s) and gyroscope rotate with the rotation of the rotor blades and the rotation of the hub around the axis, and are placed in a fixed distance to the axis of rotation of the hub, wherein each electrical pitch drive system comprises a gyroscope, said gyroscope is an integrated part of the electrical pitch drive system, and thus the gyroscope is adapted to register an angle value of the longitudinal axis of the rotor blade with respect to earth gravity,
• and a processor is adapted to calculate an angular position of the rotor blade based on said values.

A method for operating at least one rotor blade for a wind turbine said wind turbine comprising an electrical pitch control system, a nacelle, as well as a hub both placed on the top of a tower, wherein said hub is rotating around an axis and at least one rotor blade is rotatable mounted on the hub;

• said electrical pitch control system comprises at least one electrical pitch drive system each connected to a rotor blade and an electrical pitch motor;
• wherein the electrical pitch drive system(s) and the motor(s) are placed in the hub, and
• said electrical pitch drive system(s) controls the motor(s) for pitching the rotor blade and in accordance with inputs registered from a first sensor and a second sensor and said electrical pitch control system further comprises at least one gyroscope placed in the hub in a fixed distance to the axis of rotation of the hub and the electrical pitch drive system(s) and the gyroscope(s) are rotating in a fixed distance to the axis of rotation of the hub, wherein
• a gyroscope(s) is/are placed in each of the electrical pitch drive systems and each in a fixed distance to the axis of rotation of the hub and thereby being an integrated part of each electrical pitch drive system,
• and when the rotor blade(s) rotate, the hub is rotating, by which rotating the gyroscope(s) indicates a direction of the rotor blade with respect to earth's gravity,
• and whereby the electrical pitch control system is detecting a direction/angular position of the center axis of the rotor blade with respect to the tower and parallel to the gravitational vector.