Optimal Control of Wave Energy Converters Using Epsilon-Trig Regularization Method

TL;DR

This paper applies the Epsilon-Trig Regularization Method to optimize control strategies for wave energy converters, effectively handling singular arcs and switching complexities to maximize energy harvesting.

Contribution

It introduces the use of ETRM for WEC control problems, addressing the challenge of characterizing optimal control structures with singular arcs and switching.

Findings

ETRM yields high-quality control solutions for WECs.

The method effectively manages singular control arcs and switch timings.

Comparison shows improvements over existing approaches.

Abstract

The wave energy converter (WEC) devices provide access to a renewable energy source. Developing control strategies to harvest maximum wave energy requires solving a constrained optimal control problem. It is shown that singular control arcs may constitute part (or the entire) of extremal trajectories. Characterizing the optimal control structure, especially with the possibility of many switches between regular and singular control arcs, is challenging due to lack of \textit{a priori} information about: 1) optimal sequence as well as number of the regular and singular control arcs, and 2) the corresponding optimal switch times (from a regular to a singular arc and vice versa). This investigation demonstrates the application of a recently developed construct, the Epsilon-Trig Regularization Method (ETRM), to the problem of maximizing energy harvesting for a point-absorber WEC model in the presence of control constraints. Utility of the ETRM for the WEC problem is demonstrated by comparing its high-quality results against those in the literature for a number of test cases.