Discussion on Controls Reducing the Non-Operating Time of a Point-Absorber Wave Energy Converter

Abstract

　The Japanese government has set a target for renewable energy to account for 36–38 % of the electricity supply by 2030. Wave energy is one of the ocean renewable energy sources. This study aims to enhance the workability of a point-absorber wave energy converter (PA-WEC). A PAWEC float has a physical limitation in its heave motion, and exceeding this limitation necessitates operation suspension to avoid damage. This study proposes a control strategy designed to reduce the non-operating time of a PA-WEC by deriving control force coefficients to keep heave motion within the limitation. Additionally, investigation on the effectiveness of switching control scenarios is also conducted. The results indicate that the workability of the PA-WEC is improved, with validation performed through case studies involving the heave limitation up to 3 meters.