Study on Practical Control Force Decision to Improve Facility Utilization of PA-WEC

The Japanese government has set a goal of increasing the share of renewable energy to 36–38% by 2030. Wave energy is one of the sources of renewable energy from the ocean. In this study, we focused on a floating point-absorber wave energy converter (PA-WEC), which has a simple structure like a traditional buoy can be farmed relatively easily to ensure safety. The PA-WEC generates energy by utilizing the heave motion of the floating part. We analytically obtain the control force that maximizes the average power output of the PA-WEC in understood irregular waves, which are defined as the superposition of regular waves. If the float’s range of motion were infinite, the maximum power generation possible based on linear theory can be achieved. However, increasing the range of motion would result in higher construction and operation costs, while reducing the range would limit the operable wave conditions and decrease facility utilization. Therefore, it is very important to improve equipment utilization while keeping the range of motion small. This study proposes a practical control strategy with the objective of enhancing the facility utilization of the PA-WEC while ensuring that the heave motion remains within physical constraints. The effectiveness of the control strategy in suppressing the range of float motion and consequently improving facility utilization without being care about the optimal solution in linear theory is discussed.