Isolated AC-DC Interleaved Converter for MVDC Collection Grid in HVDC Offshore Wind Farm

This paper proposes an AC-DC converter with high-frequency isolation using the interleaving technique associated with an interphase transformer. Based on a medium-voltage DC (MVDC) isolated port, this configuration is proposed for applications regarding offshore wind energy conversion systems (WECSs) with high-voltage DC transmission (HVDC). As an alternative to increase the power density on offshore systems, the use of DC-DC converters to process the energy produced by the wind turbines is a modern trend in this type of configuration. This topology can be used in WECSs as the interconnection between the MVDC transmission bus and the wind turbines (WTs). The use of full-bridge modules per phase in the primary side shares the current among the semiconductors, with consequent reduced losses at high power levels. Besides, the high-frequency step-up transformer leads to reduced overall dimensions. With the use of neutral point clamped (NPC) converters connected in cascade in the secondary side, it is possible to reach obtain a MVDC output without the increase of voltage stresses on the semiconductors.