Development of a methodology for collaborative control within a WEC array

Abstract

It has been established that Wave Energy Converters efficiency can be improved by control. One of the main challenges of reactive control is the non-causality of the optimal controller. This study presents a methodology to solve the non-causality issue by providing a deterministic forecast of the controlled body velocities. This forecast is achieved by using the measurements of the states of the most up wave device of the array. The reactive control approach also implies strong instabilities due to the extreme dynamics of the controlled devices. The proposed method suggests to mitigate this behavior by applying a window function on the optimal controller impedance. In order to maximize the efficiency of the resulting control and ensure the robustness of the system, a stability analysis is conducted. Optimal sets of parameters are determined and applied to a time domain simulation of an array of 10 cylindrical floating WECs. The results obtained show an average efficiency of the array of 83% of the maximum energy retrievable in the waves.

Keywords

• Wave energy converter
• Optimal control
• Causality
• Energy
• Efficiency
• Stability