Model Predictive Energy-Maximising Tracking Control for a Wavestar-Prototype Wave Energy Converter

Abstract

To date, one of the main challenges in the wave energy field is to achieve energy-maximizing control in order to reduce the levelized cost of energy (LCOE). This paper presents a model predictive velocity tracking control method based on a hierarchical structure for a Wavestar-like deivce in the WEC-SIM benchmark. The first part of the system structure aims to estimate the wave excitation moment (WEM) by using a Kalman filter. Then, an extended Kalman filter (EKF) is chosen to obtain the amplitude and angular frequency of the WEM in order to compute the reference velocity. Following this, a low-level model predictive control (MPC) method is designed to ensure the wave energy converter (WEC) tracks the optimal reference velocity for maximum energy extraction from irregular waves. Two Gaussian Process (GP) models are considered to predict the future wave excitation moment and future reference velocity, which are needed in MPC design. The proposed strategy can give a new vision for energy-maximizing tracking control based on MPC.

Numerical Study of an Innovative Concept for a Multibody Anti-Pitching Semi-Submersible Floating Wind Turbine

“…The MBAPSF consists of a 5 MW braceless semi-submersible FOWT designed by Luan [22] and three Wavestar WECs [23]. The 5 MW wind turbine was developed by the National Renewable Energy Laboratory (NREL).…”

“…For the PTO system of the Wavestar WEC, the PTO force and the wave energy power produced by the PTO can be expressed as [18,23]:…”

Identification of Multi-Innovation Stochastic Gradients with Maximum Likelihood Algorithm Based on Ship Maneuverability and Wave Peak Models

“…However, the above methods do not consider the problem that, under wind and wave disturbances, the ship's heading will sway with the wave disturbances, and the automatic steering gear will strike the rudder when there is a heading deviation [48][49][50]. In order to avoid frequent steering under wind and wave disturbances, wave filters need to be designed [51][52][53]. When using the commonly used filtering methods, the peak frequency acquisition time is long and it is easy to cause excessive phase lag in the control system.…”