A Control Architecture for Energy Management and Battery Integration in a Stand-Alone Heaving Wave Energy Converter

Abstract

This paper presents an integrated control framework for a stand-alone wave energy converter (WEC) system equipped with battery storage and load-side regulation. The core of the proposed system is a supervisory energy management system (EMS) that adaptively governs the operation by transitioning between reactive control, damping control, and power-shedding modes in response to wave conditions and the battery’s state of charge (SoC). To ensure efficient energy harvesting, a variable step-size maximum power point tracking (MPPT) algorithm is employed to dynamically tune the damping and stiffness coefficients of the power take-off (PTO) mechanism. The EMS operates alongside a battery-side controller responsible for regulating the DC bus voltage through controlled charging and discharging, thereby ensuring voltage stability under fluctuating sea states and load variations. A load-side controller guarantees balanced three-phase AC power delivery, maintaining sinusoidal voltage and current profiles during dynamic load conditions. The proposed control system is validated through detailed MATLAB/Simulink simulations and hardware-in-the-loop (HIL) experiments. The findings demonstrates the EMS’s ability to manage power flow efficiently and maintaining safe SoC levels under high-energy conditions, while performing load disconnection during low-energy periods to prevent battery depletion. Both simulation and experimental outcomes demonstrate reliable voltage regulation, coordinated control mode switching, and effective system response to variable sea states and load demands.