Circumstance Loads And Structure Strength Analysis Of Offshore Wind Turbines

With the consumption of energy sources, renewable energy sources are being developedall over the world. As an outstanding new energy source, wind power obtains the globalattention. While working in complicated circumstance, offshore wind turbine suffers varies randomloads, such as wind, wave, current and earthquake etc. Even under extreme condition, offshore wind turbinemight be affected by several extreme loads also. So, its structure strength should be strong enough both instatic state and dynamic state. For this reason, there are important theoretical significance and practicalvalue how to determine the design circumstance parameters in reasonable way, the methods ofdynamic response analysis and dynamic, static strength evaluation.Therefore, in this paper, combining a5MW offshore turbine base structure example, themain contents are as follows:1.The main circumstance loads that the offshore turbine suffered were introduced systematically.The impulse wind speed and random wave elevation were calculated based on the harmony superpositionprocess of random method. As well as, on the basis of momentum-blade element theory and Morisonequation, the dynamical wind loads and wave loads were obtained separately.2.According to relevant standards, the pile-soil interaction theory and model of offshore turbine werestudied.3.On the basis of joint probability distribution and combining the equivalent load effecttheory, a new determine method of offshore design extreme circumstance parameters has beentried. In line with the East Sea long-term circumstance testing data, the5MW offshore turbinedesign extreme circumstance parameters were calculated. The results showed that: the newmethod suitably described the alliance affection of extreme circumstance parameters, andreduced the design parameters reasonably.4.FEM software Ansys was chosen to build the modal of offshore turbine base structure,and obtaining the vibration characteristics by model analysis. Meanwhile, the transientdynamic response analysis of turbine base structure were researched both under the affect ofseparate load and loads combination, and the dynamic response characteristics under differentload cases were studied.5.According to relevant standards, a simple practical strength assess method of offshoreturbine base structure was summed up, and with this method, the dynamic and static strength of a5MW offshore turbine were evaluated. While comparing the results, the influence ofdynamic effect, to structure strength were also obtained.