Site-specific design optimization of horizontal-axis wind turbine systems using PSO algorithm

Due to the complexity of wind turbine systems (WTSs) containing multiple components, design parameters of a WTS must match each other in order to produce electrical energy at a lower cost and a higher efficiency. In this study, a framework for site-specific design optimization of a horizontal-axis WTS is proposed. It is based on cost reduction and the objective function is the produced energy cost. The cost of energy model proposed by the National Renewable Energy Laboratory is utilized. In order to compute turbine output power that results in annual energy production, a new approach is proposed to model the power coefficient of rotor for fixed-speed WTSs. Design optimizations are performed by using a particle swarm optimization algorithm, which appears to be efficient for this type of problem. WTSs in northern Europe and the Mediterranean were studied. Results show that optimized WTSs for these sites have high profitability in terms of cost and amount of energy when compared with reference WTSs installed in these sites. Parametric analyses are also undertaken in order to evaluate the effect of wind characteristics on the produced energy cost for both types of WTSs and the effects of rotor tip-speed ratio and turbine-rated power on the design parameters and produced energy cost for fixed-speed WTSs. It is concluded that rotor tip-speed ratio has strong effects on design wind speed for fixed-speed WTSs and on the cost of kWh.