The Voith Turbo system uses a hydrodynamic converter with a planetary gear stage. Experimental machines with hydraulic drives have not generally found favour in the wind industry in the past. However, this concept enables the turbine rotor to operate at variable speed, thus maximising aerodynamic efficiency at all wind speeds and increasing energy yields. It also provides damping between the rotor and the electrical generator, allowing the use of synchronous generators, which are simpler and lighter than the more commonly used induction generators. They can also provide reactive power when required but do not draw it, and the inherent damping helps reduce shocks from grid faults or disturbances. The drive concept also enables a 26-50% reduction in power train weight and less space is required in the nacelles of the wind turbine, according to Voith. The "highly dynamic" control described by Voith Turbo Wind GmbH occurs in up to 20 milliseconds and the use of a synchronous generator eliminates the need for power electronics for frequency conversion, making it possible to achieve excellent power quality.
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Senior Renewable Energy Analyst (WindGEMINI Product Lead) DNV GL Bristol (City Centre), City of Bristol