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HVDC Connection of Offshore Wind Farms to the Transmission SystemIntroductionThis paper presents a technical and economic analysis to evaluate the benefits and drawbacks of grid connecting offshore wind farms through a dc link.2TECHNICAL ANALYSIS OF THE CONNECTION OPTIONScaseTransmission typeFailure mode100MWACLinkDCLink250MWACLinkDCLink500MWAC 150 kVHV AC cableTransformerAC 400 kVHV AC cableTransformerDCStations/cableTransformer100MW AC

100MW DC

200MW AC

500MW AC

TECHNICAL ANALYSIS OF THE CONNECTION OPTIONS

ECONOMIC ANALYSIS: COMPARISON OF THE CONNECTION OPTIONSO&M: operation and maintenance ENS : the value of losses and of energy not supplied

ECONOMIC ANALYSIS: COMPARISON OF THE CONNECTION OPTIONSThis especially impacts the economics of the 100-MW wind farm.Economic assessment includes sensitivity analyses of parameters, which could impact the 100-MW wind farm: distance, component costs, dc converter reliability, and dc converter losses.

ECONOMIC ANALYSIS: COMPARISON OF THE CONNECTION OPTIONS

ECONOMIC ANALYSIS: COMPARISON OF THE CONNECTION OPTIONS

CONCLUSIONFor all the case studies, the HVDC solution is more expensive than the ac, partly because of higher total investment costs at the considered connection distance of 60 km.Nevertheless, the results of sensitivity analyses performed for various parameters (connection distance, cost of cable protection, and cost and reliability of converter stations) show that HVDC appears to be the cheapest option to connect a 100-MW wind farm at distances greater than 90 km to the shore.CONCLUSIONEvaluations performed within this research activity and the present experience with VSC-HVDC connection of offshore oil/gas platforms allows us to believe that HVDC is a promising technology with growth potential for applications in the connection of offshore wind farms.