Optimal control strategy for enhancing energy efficiency of Pelamis wave energy converter: a Simulink-based simulation approach

Wave energy is a promising renewable resource due to its predictability, consistency, and low environmental impact, making it an efficient solution for electricity generation in marine environments. Among various wave energy converters, the Pelamis stands out for its simplicity and scalability; however, its energy conversion efficiency can be further improved through advanced control strategies. This research aims to enhance the energy extraction efficiency of a Pelamis wave energy converter by implementing an optimal control strategy to regulate the production torque within the power take-off (PTO) system between the Pelamis cylinders. A dynamic model of the system interacting with regular waves is developed, and optimal control theory is applied to compute the PTO torques in real-time, maximizing the energy captured. The Pelamis energy converter and its control system were simulated in MATLAB's Simulink environment. The results indicate that applying the optimal control method leads to a threefold increase in energy capture compared to the Proportional-Integral-Derivative (PID) control approach and a tenfold increase compared to the uncontrolled system. Additionally, frequency analysis of the average power output demonstrates that the energy gain with the optimal controller is achieved across all wave frequencies.