Abstract
Cost parameters for VSC HVDC transmission infrastructure have been gathered from an extensive collection of techno-economic sources. These cost parameter sets have been converted to a common format, based on a linear investment cost model depending on the branch length and the power rating of cable systems and converter stations. In addition, an average parameter set was determined as the arithmetic mean of the collected parameter sets, and included in the study. The uniform format allowed for a comparison of the parameter sets with each other, which revealed large differences between the cost parameter sets. The identified disparity between the parameter sets reflects a high level of uncertainty which can only in part be explained by a varying focus and modelling approach of their sources. This implies limitations regarding the validity of the parameters sets as well as of the results from grid expansion studies carried out on the basis of these parameter sets. Comprehensive cost reference data has been collected from realised and contracted VSC HVDC projects (back-to-back, interconnector, and offshore wind connection). The cost parameter sets have been evaluated against the reference project cost data. This evaluation has again shown large variations between the parameter sets. On average, the cost for back-to-back systems are slightly underestimated, interconnectors are overestimated, and offshore wind connections are heavily underestimated. To clearly state the validity and limitations of this comparison and evaluation, the applied methodology with its compromises and drawbacks is discussed in detail. Considering the interest in and momentum of offshore grid development, as well as the number of offshore grid investment and evaluation studies being conducted, both the availability of reliable cost reference data and the validity of investment model cost parameters need continuing attention. © 2017 Elsevier B.V