Zhaitang Island Tidal Power Dynamic Umbilical Cable Dynamic Response Research

As a kind of clean energy, tidal current energy needs to be developed. The main transmissiondevice of tidal power operation is the umbilical cable, this paper does the whole hydrodynamic andstable analysis for the umbilical cable of Zhaitang Island tidal power project by the internationaladvanced hydrodynamic analysis software Orcaflex and stability analysis software StableLinesdeveloped by DNV. The theoretical calculation formula of corresponding cable motion wasdeduced for software theoretical foundation. The environment data, power generation equipment,location of mooring lines, design parameter determination and umbilical cable design are alsoanalysed. The hydrodynamic analysis is done in accordance with standards. The umbilical cablehas a wide range of drift and big internal tension in shallow water. That’s why dynamic part of ittakes the spring-chain combination way of laying. The force acting on the cable and curvaturecould be changed by changing interval length of the cable and connection chain. To improve thefield operation model, the analysis is optimized step by step according to the comparisons betweenthe result of each model and the characteristic parameters of the umbilical cable. Due to bendingdamage at the connection position locating at top of cable, so we should add a bending restrictorhere to avoid over bending. Finally, the best way of laying for the dynamic part is that: the intervallength of cable and connection chain is3.05m and3m respectively, at the same time there is abending restrictor at the top of the cable. For the static part of umbilical cable, the StableLinessoftware is used to carry on seabed stability analysis. It found that the part can’t keep stable fromthe simulation results, so the heavy pressure of buried way is adopted to keep its stability.We could know static and dynamic part of cable is hard to stable in the shallow water fromthe analysis of this paper. The heave amplitude of floating device is large, the dynamic cable has awide range of drift, so the way of cable-chain fixed is needed. This way let chain suffer the mostforce of cable, so the internal tension of umbilical cable is significantly reduced. In the shallowwater, the current velocity of bottom is large, because attenuation is small from the surface to thebottom, the static part of cable should be pressure buried or fixed. In the actual submarine, in orderto ensure reliable, feasible and practical solution, the way of laying for cable should consider thefactors in all direction.