Wind turbine system, an assembling method of a wind turbine system, an inspecting method of a wind turbine system, and an operation method of a wind turbine system

A wind turbine system comprising:

• blades, which rotate by receiving wind;
• a nacelle, which supports the blades and rotates depending on wind direction;
• a main shaft for transmitting torque which is connected to a hub and is rotated by rotation of the hub;
• a pitch drive, which adjusts a pitch angle of the blades;
• a supporting main shaft disposed outward from the main shaft with a gap relative to the main shaft;
• at least two bearings disposed between the supporting main shaft and the hub, a center of gravity of the blades located between the bearings in an axial direction of the main shaft;
• and
• a generator, which generates electricity using rotating energy of the main shaft,
• wherein the main shaft is connected to the hub inside the hub in the axial direction of the main shaft, the hub has an opening at a far side thereof relative to the generator, and the hub has an entrance disposed between the far side and the main shaft permitting passage of the pitch drive.