Control of Wave Energy Converters with Discrete Displacement Hydraulic Power Take-Off Units

Shangyan Zou,Ossama Abdelkhalik

doi:10.3390/jmse6020031

Shangyan Zou, Ossama Abdelkhalik

Open Access

https://doi.org/10.3390/jmse6020031

Copy DOI

Abstract

The control of ocean Wave Energy Converters (WECs) impacts the harvested energy. Several control methods have been developed over the past few decades to maximize the harvested energy. Many of these methods were developed based on an unconstrained dynamic model assuming an ideal power take-off (PTO) unit. This study presents numerical tests and comparisons of a few recently developed control methods. The testing is conducted using a numerical simulator that simulates a hydraulic PTO. The PTO imposes constraints on the maximum attainable control force and maximum stroke. In addition, the PTO has its own dynamics, which may impact the performance of some control strategies.

Highlights

Introduction and BackgroundThe control of ocean Wave Energy Converters (WECs) has received a great deal of attention over the past several decades
This paper presents comparisons between some recently developed control methods; these simulations include a model for a hydraulic power take-off (PTO), which imposes constraints on the displacement of the buoy and on the maximum possible control force
The main conclusion of this paper is that a controller that is optimal in theoretical analysis might not be optimal when tested in a practical test environment

Summary

Introduction

Introduction and BackgroundThe control of ocean WECs has received a great deal of attention over the past several decades. In recent years in particular there have been significant developments with respect to maximizing the harvested energy from WECs from a control system analysis and design perspective Many of these control methods were proposed for ideal conditions in the absence of stroke or force limitations, and assuming ideal power take-off (PTO) units. This paper presents comparisons between some recently developed control methods; these simulations include a model for a hydraulic PTO, which imposes constraints on the displacement of the buoy and on the maximum possible control force. These simulations highlight some insight regarding the needed reactive power for some of the discussed control methods. The control methods discussed in this paper are tested using hydraulic PTOs for the first time in this paper

Results

Discussion

Conclusion