Multi-objective energy-cost design optimization for the variable-speed wind turbine at high-altitude sites

As the development of wind power utilization, onshore wind turbines have been installed at various sites with different altitudes. Although the site-specific design is an effective way to reduce the levelized energy cost of the wind turbines, the influence of the site altitude on the energy cost is not considered in the existing site-specific designs. To fill the knowledge gap, this study presents the site-specific design optimization of the wind turbines at the high-altitude sites, based on a multi-objective trade-off between maximization of the energy production and minimization of the production cost. For this purpose, two improved estimation models of the annual energy production and the annual production cost are firstly introduced for the high-altitude wind turbines. On this basis, the multi-objective energy-cost optimization problem is formulated as two nonlinear functions relevant to two key designed parameters: the rated power and the rotor radius. After that, a multi-objective particle swarm optimization method is proposed. Finally, the proposed method is applied to the Huitengxile and Maanshan wind farms, located in Inner Mongolia and Yunnan-Kweichow plateaus of China, respectively. The results show that the energy cost has been noticeably increased by about 15% and 18% in the two applications comparing with the results ignoring the site altitude. Moreover, a trade-off between various alternative energy-cost solutions has been provided by the generated set of the optimally designed parameters. Thus, a two-step criterion has been proposed to help the turbine designers select the designed parameters according to their preference.