June-Seok Lee, Eunsil Lee, and Kyo-Beum Lee, "Hybrid Parallel Three-Level Converter Topology for Large Wind Turbine Generation Systems," in Proc. ISIE Conf., Jun. 2014, pp. 515–520. > Paper

This paper proposes a hybrid parallel three-level converter topology for large wind turbine generation (WTG) systems and its control

method. The proposed topology focuses on a machine side of a back-to-back converter. It consists of one conventional three-level

neutral-point clamp (NPC) converter and numerous reduced-part converters, which are connected in parallel depending on rated

power of a WTG system. In comparison with a conventional parallel three-level converter topology, in the proposed topology,

switching devices are reduced by using reduced-part converters. Moreover, the proposed topology achieves the existing advantages

of the parallel converter topology. The reduced-part converter guarantees the sinusoidal current at a particular power factor which

does not become a unity power factor. Therefore, a power factor compensation control is performed in one conventional three-level

NPC converter to mitigate the disadvantage related with the power factor. The simulation of 2-parallel three-level converters topology​

is conducted to identify the practicality of the proposed topology and validity of its control method.