Lowering the levelized cost of energy (LCOE) for mass-adjustable-buoy-based wave energy converters

Abstract

This study is aimed at optimized control strategies for ocean wave energy converters (WECs) with mass-adjustable buoys. The conventional buoys are usually with fixed parameters and cannot perform well when wave periods are varying. In this study, mass-adjustable buoys are utilized to deal with the variations of wave periods. In order to coordinate with mass-adjustable buoys, four strategies, maximum power (MP) strategy, power factor priority (PFP) strategy, unit power factor (UPF) strategy and maximum capacity factor (MCF) strategy, are proposed and analyzed. The concept of levelized cost of energy (LCOE) is adopted to evaluate the economic efficiencies of different strategies. Hill-climbing method and reverse-hill-climbing method are adopted to approximate the target point because other kinds of methods usually require too much information and cannot perform well in practical engineering. The simulation and experimental results indicate that the LCOEs for these four strategies are respectively $0.7596/kWh, $0.7836/kWh, $0.3936/kWh, and $0.3807/kWh. Additionally, when the wave period and elevation changes from case 3 to case 7, the average active power is improved by 17.80% through adjusting the mass of the buoy. Experiments are carried out as well to verify the hill-climbing method and reverse-hill-climbing method.