Recent Control Technologies for Floating Offshore Wind Energy System: A Review

This paper presents the recent control technologies being researched for floating offshore wind energy system (FOWES). FOWES has been getting many attentions recently as an alternative energy system utilizing vast sustainable wind resource away from land with little restriction by human societies, artificial and natural obstacles. However, not only due to the harsh environmental conditions such as strong wind, wave, and current, but also due to the platform motions such as surge, sway, heave, pitch, roll, and yaw, there could occur many problems including less energy capture than expected, frequent emergency stops, turbine structural instability, and fatigues resulting in early failures, which stay the levelized cost of energy (LCOE) still high compared to conventional fixed offshore wind energy system. These risks could be lowered by operating the turbine close to the optimum point and harvesting wind energy efficiently even under strong wind conditions with the properly applied control technologies, while reducing the loads on structural components. Many researches have been actively going on not only by numerical approaches, but also by experimental tests. This study is wrapping the most recent researches on control technologies for promising floating offshore wind energy system according to different substructure designs such as a spar type, semi-submergible type, tension-leg platform (TLP) type, and barge type, and discusses about its challenges as well.