In order to improve the reliability of mooring system of floating wind turbine under extreme sea conditions, a constant tension mooring system was proposed in this paper. In extreme sea conditions, when the mooring force reaches the set value, the mooring system automatically releases the weights stored on the floating body, and the floating body moves along the waves with a basically constant mooring force. Through coupled time-domain simulations, the dynamic responses of 5-MW-CSC semi-submersible wind turbine with the constant tension mooring system were studied under the extreme conditions with 50-year return period.
Offshore floating wind power is maturing and has significantly reduced costs over the past few years. Compared with fixed offshore wind power, floating wind power is still in the stage of small-scale development. With the rapid maturity of technology and the continuous emergence of demonstration projects, it is expected to realize large-scale commercial development by 2030. According to the prediction of the European Wind Energy Association, the global installed capacity of floating wind power will reach 15 GW by the end of 2030. It is conservatively estimated that the cost of floating units will decrease by 38% by 2050. At that time, 150 GW of offshore floating wind power will be developed in Europe, which means that one-third of offshore wind power will be floating wind power in deep sea.
Mooring and anchoring technology will be the key research and development field of floating wind power. A well-designed mooring system can effectively maintain the safety and stability of wind turbine in extreme environmental conditions such as typhoon and tsunami. In the actual project, the mooring system of offshore floating wind turbine accounts for 20% - 30% of the total investment cost of the project, as a comparison, for offshore oil and gas platforms, it accounts for only 2% (Fitzgerald, 2009). Therefore, optimizing the mooring system is of great significance to promote the commercialization of offshore floating wind power.
