DC/DC converter for offshore DC collection grid

Offshore wind represents a significant clean energy resource. Current offshore wind farm designs use a conventional AC collection network in which the wind-turbine AC output voltage is stepped up to a medium-voltage suitable for wide area connection. A DC offshore collection grid offers an attractive alternative to an AC architecture as it avoids the charging current issues associated with its AC counterpart, and offers the potential for lower system-level losses and reduced size and weight. Such DC architectures depend on high-power DC/DC converter to step up the wind-generator DC output to a voltage compatible with efficient interconnection. This paper proposes an alternative DC collection network based around modular DC/DC converters, realised through parallel-series connection of multiple low-power rated modules. Besides, a bi-directional DC/DC converter is also involved to perform the black start operation of the wind turbine.