Design of a probabilistic decision support tool for the cable installation of an offshore wind farm

Abstract

During the past years a lot of attention has been drawn towards the development of renewables, due to the expected depletion of fossil fuels and political decisions. Offshore wind energy is considered as one of the most promising renewable energy sources, however the cost of offshore wind farms have not yet reached competitive levels. Hence public-private partnership initiatives, such as FLOW, were developed, aiming the reduction of the high cost of offshore wind farms. The current thesis is part of the FLOW project and its main goal concerns the development of a probabilistic decision support tool which will help professional concept engineers in comparing different cable installation scenarios by taking into account uncertainties. The tool estimates the time needed to complete the cable installation and by this estimation, an insight to the total cost of the cable installation can be provided. Thus the user can exploit the results provided by the designed tool in order to decide the optimal installation scenario. Within the scope of the project the dependence of wind speed and wave height, was investigated using Copulas functions and random weather time series were constructed based on the estimated dependence. Also an algorithm which takes into account the uncertainties regarding the performance of the installation operations as well as the risk of potential failures was developed. The algorithm provides as output the CDF curve of the duration of a cable installation scenario. Based on the produced curve the user is able to estimate the duration of a cable installation scenario within a confidence level. Finally the designed tool was used to simulate a realistic cable installation test case, provided by Van Oord. The results from the simulations indicate that the designed tool provides a better estimation of the duration of a cable installation scenario, since it takes into account more realizations of weather conditions, compared to the common practice which simulates this scenario for a number of observed weather time series. Also it can be used to compare different cable installation scenarios by estimating the time needed for their completion and provide an insight on the expected cost, incorporating weather uncertainties and failure risks.