Applications

Wind Turbine Grounding

Dangerous Voltages and Currents Present on Wind Power Turbine Generators – Must be Discharged to Ground for Reliable Operation

The wind turbine generator industry continues to be the fastest growing clean energy source where reliability is key to profitable operation. Bearings and other critical components frequently fail because of high shaft currents generated in the wind turbine nacelle. Reliable maintenance-free protection from rotor shaft high voltages and currents will reduce maintenance costs and improve up-time for wind turbine owners and operators.

Problem: Wind turbine generator stator windings and rotors are directly connected to the power grid. Unlike the stator, the rotor is connected to the same grid via a converter. The converter makes operation possible at variable rotor speeds while maintaining constant stator voltage and frequency outputs to the grid. This system introduces dangerous rotor shaft voltages, and due to the high frequency converter switching, the generators, gear boxes, and other critical components are exposed to dangerous high frequency shaft currents causing EDM (Electrical Discharge Machining).

Solution: A new shaft grounding technology known as AEGIS WTG (Wind Turbine Shaft Grounding System) uses circumferential rings of conductive micro fibers to discharge these harmful currents to ground. The AEGIS WTG shaft grounding system was successfully tested and applied to a GE 1.5 MW generator.

Up-tower voltages of 1200 volts peak were measured on the shaft of the turbine. After AEGIS WTG was installed, the voltage was reduced to 32 volts peak. Concurrently, 56 amps of high frequency shaft currents are being diverted through the AEGIS WTG shaft grounding ring.

The AEGIS WTG, a grounded conductor ring, is placed between the stator winding and the rotor. Dangerous rotor shaft voltages are diverted to ground, protecting bearings and other vulnerable components.