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 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 pitch bearing has a cavity therein and the rotor bearing has a cavity defined by the inner diameter of each bearing,

• the lightning protection device includes:
• a blade arrester located near the blade tip and at the side of the blade, a down lead of blade connected to the blade arrester, a lightning-proof element of the pitch bearing and a lightning-proof element of the rotor bearing, wherein the lightning-proof element of the pitch bearing is provided at the blade root, one end of the lightning-proof element of the pitch bearing is connected to the down lead of blade and the other end is connected to the lightning-proof element of the rotor bearing;
• wherein the lightning-proof device forms a lightning current conducting path which is passing through the cavity of the pitch bearing, the hollow portion of the hollow rotor shaft and the cavity of the rotor bearing.