Reliability analysis of floating wind turbine dynamic cables under realistic environmental loads

Abstract

The need for more robust design of dynamic cables used for power export in floating wind turbine (FWT) systems is accentuated by the frequent occurrence of power cable failures. Such failures contribute considerably to the cost of global offshore wind farm losses. Fatigue is often times a critical consideration in the structural safety of these cables. This is understandably so, given that they experience numerous loading cycles–mainly induced by the combined action of wind and waves throughout their service life. It is therefore pertinent that the reliability level attainable by these cables is quantified and elaborated upon. In this paper, a probabilistic reliability analysis approach is developed to quantify the reliability levels of dynamic power cables. Uncertainties emanating from the randomness of realistic environmental scatter, geometric and material variables are all taken into account in this study. To facilitate the computation of the structural demands on the dynamic power cable, an efficient analytical model was developed. Key aspects such as cable–soil interaction and boundary-layer phenomenon are captured by the analytical model. Kriging metamodel is then employed to propagate relevant uncertainties into the reliability problem, making it possible to quantify the reliability levels of these cables.