Collection and transmission losses of offshore wind farms for optimization purposes

The cost of offshore wind energy has not yet reached competitive levels despite the recent technological improvements. Optimization tools designed to reduce the overall losses in Offshore Wind Farms (OWFs) may help to reduce its cost of energy. Hence, fast and accurate loss models are necessary for the optimization of the OWFs design. The aim of this paper is the development of models to calculate the power losses in the offshore cables, transformers and converters of the collection and transmission systems. All the proposed models consider the main sources of losses during steady-state operation as well as their dependence on temperature and are computationally light for the optimization process. The cable model considers the type of soil surrounding it, whereas in the converter case, the IGBT datasheet information is used to compute the losses. The power production of a 640 MW offshore wind farm situated at 50, 100 and 150 km from shore is compared against the proposed models and models in which the operating temperature dependence is not considered for both the HVdc and HVac transmission options. Although the obtained break-even distances were similar in both models, higher efficiencies for both transmission technologies were obtained when considering the operating temperature correction factors. The higher accuracy of the proposed models may help designers to better predict the profitability of OWFs.