Multi-objective optimization and dynamic response predictions of an articulated offshore wind turbine

Abstract

In this manuscript, a compliant articulated offshore wind turbine (AOWT) is proposed to operate in the transitional water depth area and a three-objective optimization mathematical model is established to optimize the main dimensions of the articulated foundation. The relative optimal solutions (pareto solutions) are obtained by the third generation non-dominated sorting genetic algorithm (NSGA-Ⅲ). The corresponding main dimensions are determined through the fuzzy comprehensive evaluation. In order to verify the robust dynamic performances of the optimized AOWT, the time domain simulations are carried out to numerically predict the AOWT responses under both rated operational and extreme survival sea scenarios. According to the results, the optimized AOWT is significantly improved in terms of construction cost, structural stability, motion performance and power generation stability, and fully satisfies the operating requirements under different sea scenarios. From the impact of different load factors on response results, the second-order load induces larger oscillations but has little effect on the mean positions of the AOWT. Both turbulent wind and second-order difference frequency second order force induce greater dynamic responses in the low-frequency region.