EMODI

EMODI is an industrial research project aiming at optimizing the dimensioning as well as both the predictive and the curative maintenances of submarine cables. It will concern the so-called static cable transmitting energy between countries and from offshore energy farms, as well as dynamic cables linking marine turbines to their electrical substation (floating or subsea fixed). The conventional, static methods on which cable dimensioning is currently based are not relevant in the case of renewable offshore farms, in particular in the case of wave energy farms due to the very fluctuating electrical power they generate. Hence, one of EMODI’s tasks will consist of developing and validating such novel dynamic methods. The project aims also at identifying the limits and innovations for the current solutions of defect search by echometry and studying solutions to overcome the limits via real-time monitoring of the state of the cables. These studies will be strengthened by tests on benches and digital simulations of the thermomechanical behavior of the cable, allowing eventually the industrial development of solutions strengthening the availability of the offshore renewable production. One particular key point is the hydro-mechanical response of the cable, designed for a 20-years life, which will be submitted to the soil friction and tidal current flow interactions (sea bed part) or to the combination of floater motions and waves kinematic excitation (dynamic umbilical part). Global behavior under flow excitation contributes to fatigue life limitations of cross section components. Measurements of global response in real sea conditions, combined with use of numerical models, are part of the project in the way to assess maintenance. This study will be matched to an electrical approach of the cable monitoring, based on online parametric estimation of the insulation electrical behavior (capacitance). The main results of the project will be in-situ monitoring strategy and systems to optimize the dimensioning of power cables, to predict the evolution of cumulative damage of the cable cross section components, to increase the reliability of marine cable design based on numerical calculations first, and to evaluate the actual fatigue during exploitation. The availability of such methodology will lead to reduce safety coefficients imposed in the existing rules and then to reduce the capital expenditure and maintenance costs which are critical points in the MRE development.