A mathematical model is proposed for predicting static water resistance of offshore wind turbine installation vessel and to calculate the resistance of a certain type of offshore wind turbine installation vessel. In order to verify the efficiency of this mathematical model, the comparison between results calculated by it and actual model test has been made. The conclusion indicates that the estimation method is reliable, and it can provide reference for resistance calculation of similar type vessels. Currently in China, there are no references for the effective prediction and calculation of the resistance for offshore wind turbine installation vessel. Therefore the proposed method has important value of engineering application in the areas of effective resistance estimation method of offshore wind turbine installation vessel, as well as the numerical calculation of ship hydrodynamics.
Compared to onshore wind turbines, offshore wind turbines take advantage of wind speeds which are more constant and stronger than those on land. Since many large electricity load centers are located near coastline in China, larger wind turbines can be installed closer to these areas to supply energy in a more economical way. Wind turbine transportation and installation are key issues for offshore wind farm construction, especially for large size turbine installation in ultra-shallow water like intertidal zone with water depth less than 5m. The traditional installation vessels with large design drafts are likely to be trapped in shallow water zones. It is usually impossible to carry out turbine installation in shallow water. This paper presents a set of innovative installation vessel concept and corresponding methods for ultra-shallow water zone include ultra-shallow draft crane vessel and ultra-shallow draft barge. The main purpose is to simplify the installation procedures and reduce total investment.
Current methods for installation of offshore wind turbines are all sensitive to the weather conditions and the present cost level of offshore wind power is more than twice the cost of land-based units, increasing with water depth. This paper presents numerical simulations of a novel experimental gripper design to reduce the environmental effects applied to a catamaran type of vessel during wind turbine installation. In SFI MOVE project in NTNU Aalesund, our team proposed a novel wind turbine installation process. A new catamaran vessel will carry pre-assembled wind turbines to the installation location. Two new designed grippers on the deck will make a lifting operation to install the wind turbine onto the turbine foundation. Three prismatic grippers with several rolling contact points at the end are attached in an arc at the catamaran’s aft, designed to grasp the turbine foundation in order to make a connection between the two in the horizontal plane. This paper will only emphasize the contact responses between the turbine foundation and the three grippers during the wind turbine installation process. Numerical simulations are carried out using the virtual prototyping framework Vicosim which is developed by NTNU Aalesund. The simulation results show validation of a key part of the proposed new wind turbine installation idea.
Abstract
In order to accurately evaluate the influencing factors of the structural safety of the self-elevating offshore wind turbine installation platform, the load in the standing operating state and towing state is studied in this paper, which includes self-gravity load, wind load, current load, wave load, wave-induced inertia force, dynamic amplification load and operating load. This paper focuses on two working states of the platform. In the standing state, the effect of environmental load, as well as the dynamic amplification load is considered under both normal operating condition and storm condition. In the towing state, mainly the wave environmental load is taking into consideration. According to the data calculated above, the strength calculation is carried out. The results show that the design strength of the platform meets the requirements. This calculation method can provide a basis for the design of the self-elevating platform.
Virtual Prototyping of a Low-Height Lifting System for Offshore Wind Turbine Installation