A Techno-Economic MILP Optimization of Multiple Offshore Wind Concessions

Within this work, a techno-economic optimization of large offshore wind regions, consisting of multiple concessions is developed and investigated. Currently, the practice within the European offshore wind industry is for countries to designate an offshore wind power zone within their exclusive economic area (EEA). This zone is then further divided into individual concessions which are auctioned off to developers. Developers then optimize each individual concession independently. As such, research on electrical system optimization has been heavily focused at the scale of the individual concession, ignoring the possible gains that come from current or future developments in neighboring concessions within the same region [1]. It is believed that there is a significant opportunity for both cost savings and increased system reliability by optimizing an entire offshore wind zone prior to the development of each individual concession [2]. This work attempts to investigate these opportunities.

The techno-economic optimization is formulated as a mixed integer linear program (MILP). Typical voltage levels for HVAC and HVDC transmission are included as well as mid-point reactive power compensated HVAC transmission. Mid-point compensation has been shown to extend the economic range of HVAC systems [3]. The optimization finds a global minimum for the lifetime cost of energy. To guarantee the feasibility of the results, a full “AC” analysis of the proposed technical design is performed. The lifetime costs accounted for are capital expenditures (CAPEX) related to material and labor during the construction phase, operating expenditures (OPEX) related to plant maintenance and operation, and the Expected Energy Not Served (EENS). The use of site-specific wind profiles and turbine specific power curves make for geographically and technologically relevant solutions.

To quantify the possible benefits of optimizing an entire region, a case study within the Belgian North-sea is investigated. The offshore wind zone within the Belgian EEA consists of 10 concessions all at varying degrees of development. The zone spans an area of 175 km2 and will have a total capacity, once fully developed, exceeding 2.2GW [4]. The optimal solution is compared to the existing solution in order to extract the areas in which improvement can be made using the proposed optimization method.