Converters for HVDC Transmission for Offshore Wind Farms: A Review

Unrestricted use of conventional sources of energy has led to over extraction and depletion in these resources. To continue with the economic, technological and industrial development inspires the search for non-traditional energy sources like the solar, tidal, wind, geological i.e. geothermal energy sources, etc. Extraction of energy from these resources is based on factors like site, cost of installation, cost of production, transmission of power, etc. Wind energy source is one of the most promising and mature sources amongst the non traditional sources of energy. Particularly, offshore wind farms are more suitable for large scale production. However, long distances transmission of power is a matter of concern. High Voltage Alternating Current (HVAC) or High Voltage Direct Current (HVDC) systems can be used for transmission of bulk power over long distances. This paper gives a summary of existing HVAC and HVDC systems. Also, it reviews various converter topologies used in HVDC transmission systems. It also discusses in detail MMC topology for HVDC transmission.