Parametric Analysis and Methodology for Optimal Wave Energy Converter Array Design

Abstract

Wave energy is increasingly recognized as a viable renewable energy source, offering significant potential for sustainable power generation. At the core of harnessing this potential lies the design of wave energy converter (WEC) arrays, which play a crucial role in maximizing energy extraction. Traditional array optimization approaches often emphasize mechanical energy absorption in scenarios without active control by maximizing the q-factor, defined as the ratio of the total average power absorbed by the array to the average power absorbed by all individual floats without interactions. However, such methods neglect the pivotal role of control strategies in determining the ultimate electrical energy output, including the effects of energy conversion losses. To bridge this gap, this study adopts a control co-design (CCD) methodology, which simultaneously considers array layout design and control strategy integration. This novel approach aims to optimize the electrical energy output of WEC arrays by addressing both hydrodynamic interactions and electrical efficiency. 

The study employs point absorbers as the primary WEC type and utilizes a model predictive control (MPC) framework to optimize energy capture while respecting displacement constraints for safe operation. A detailed parametric analysis is conducted on 2-float arrays with varying float radii, drafts, and displacement constraints under regular and irregular wave conditions. By incorporating the influence of power losses in the control system, the design process transitions from a purely mechanical focus to an integrated optimization framework aimed at maximizing electrical power output. 

Building on insights from the 2-float array analysis, the study proposes a comprehensive methodology for designing 4-float arrays adapted to specific wave climates. Key considerations include the interplay between mechanical parameters, such as float radius and draft, on energy absorption and electrical output efficiency. The role of control-induced displacement constraints in determining optimal float spacing and array orientation is examined, along with the impact of electrical energy losses on the array's q-factor. By balancing these factors, the proposed methodology aims to identify configurations that achieve both high energy efficiency and safe operation. 

The feasibility and applicability of the proposed methodology are demonstrated through a case study using field wave data from China Oceanic Information Network. This real-world validation integrates local wave characteristics into the design process, enabling the evaluation of optimal array configurations for maximizing electrical energy output. The case study highlights the importance of considering hydrodynamic interactions, control-induced electrical losses, and site-specific wave conditions in designing practical and efficient WEC arrays.