Wind turbine generator system and lightning protection device thereof

A lightning protection device for a wind turbine generator system including a rotor connected with a hub and at least one rotor blade, wherein the at least one rotor blade is connected to the hub via a blade pitch bearing, the hub is connected to a hollow rotor shaft and the hollow rotor shaft is supported by at least one rotor bearing, and wherein the blade pitch bearing has a cavity therein and the at least one rotor bearing has a cavity defined by an inner diameter of the rotor bearing,

• the lightning protection device includes:
• a blade arrester located near a blade tip and at a side of the at least one rotor blade, a down lead of the at least one rotor blade connected to the blade arrester, a lightning protection element of the blade pitch bearing and a lightning protection element of the at least one rotor bearing, wherein the lightning protection element of the blade pitch bearing is provided at a blade root, one end of the lightning protection element of the blade pitch bearing is connected to the down lead of at least one rotor blade and another end is connected to the lightning protection element of the rotor bearing;
• wherein,
• the lightning protection device forms a lightning current conducting path which is passing through the cavity of the blade pitch bearing, a hollow portion of the hollow rotor shaft and the cavity of the rotor bearing;
• the lightning protection element of the rotor bearing includes a slip ring with at least one brush;
• and
• the slip ring of the lightning protection element of the rotor bearing is arranged around an electrical or hydraulic slip ring unit of the wind turbine generator system.