Practical Optimal Control of a Wave-Energy Converter in Regular Wave Environments

TL;DR

This paper presents a practical optimal control framework for wave-energy converters that balances power generation with device safety and operational costs, demonstrated through simulations and real-time application.

Contribution

It introduces a novel control formulation incorporating constraints and control costs, solved efficiently as a quadratic optimization problem for WECs.

Findings

Effective trade-off between power output and device safety.

Quadratic optimization enables real-time control implementation.

Simulation results validate the approach's practicality.

Abstract

A generic formulation for the optimal control of a single wave-energy converter (WEC) is proposed. The formulation involves hard and soft constraints on the motion of the WEC to promote reduced damage and fatigue to the device during operation. Most of the WEC control literature ignores the cost of the control and could therefore result in generating less power than expected, or even negative power. Therefore, to ensure actual power gains in practice, we incorporate a penalty term in the objective function to approximate the cost of applying the control force. A discretization of the resulting optimal control problem is a quadratic optimization problem that can be solved efficiently using state-of-the-art solvers. Using hydrodynamic coefficients estimated by simulations made in WEC-Sim, numerical illustrations are provided of the trade-off between careful operation of the device and power generated. Finally, a demonstration of the real-time use of the approach is provided.