Study On The Design Of Simple Offshore Wind Turbine Foundation

With the continuous developing and utilization of new energy,the advantages of offshore wind power are more and more outstanding,and the development of offshore wind turbine has become a trend in the world.However,the current development is far from ideal state,and the main restraining factors include: the technology of design,installation,operation for offshore wind turbines is not perfect;the electricity price is low and the offshore wind turbine is highcost.Offshore wind turbine structures are not only marine engineering structures but also tall and slender structures.They are dynamic sensitive structures,and the foundations are in complex and harsh environment.Offshore wind turbine foundations are the key components for the whole structure,and how to design and study foundations' structure rationally has been important and difficult.So it is necessary to do further research on offshore wind turbine foundations to promote offshore wind power development.In view of that the main and current offshore wind farms are in shallow sea,so in this paper,the study on the design of simple offshore wind turbine foundation in the coastal waters of the Bohai sea are done to provide a reference for offshore wind farm development in China.The main research work of this paper is divided into the following sections:1.Firstly,the selection of offshore wind turbine foundation form is done in the paper.This part determines the factors influencing the choice of foundation form,and summarizes the basic characteristics of various foundation forms.By comparing the applicable scope,construction,installation,and the cost of various forms,the advantages and disadvantages of these foundations are summarized to select a best foundation form in Bohai sea.2.The basic design of tripod foundation has been done.Analysis of the dynamic characteristics of the offshore wind turbine structure are done with ANSYS software.This part introduces the environmental loads including wind,wave,current and ice load.Also,the response analysis of offshore wind turbine foundation in extreme static load and dynamic load are done in this part.The responses of the foundation structure under extreme static loads and dynamic loads are analyzed.Comparing the result of impact of environmental load on the foundation structure to determine the key load and the main failure modes for the design of offshore wind turbine foundation.3.The fatigue failure analysis of foundation structures are done.The offshore wind turbine structure is a kind of special marine flexible vertical structure.Resulted by the action of alternative marine environmental loads,the structure will easily generate alternative stress and fatigue damage.Fatigue analysis for offshore wind turbine foundation is very important.The structure fatigue damage under different environmental loads and the coupled fatigue damage are analyzed with some theoretical methods in this part to define the main points of fatigue analysis for offshore wind turbine foundations.4.It is found that the dynamic ice load can cause strong vibration of the structure.The significant acceleration and alternate stresses will directly threaten the turbine and the structure and reduce the life of the structure.In view of this problem,the simple ice-resistant structure for offshore wind turbine foundation is designed in this part by referring the offshore oil platform in Bohai.A conceptual form of ice-resistant cone is proposed and the ice-resistant effect of the structure is verified by finite element analysis.