Decentralized Model Predictive Control for Wave Energy Converter Arrays

Abstract

Most of the research on wave energy conversion has been focused on the characterization of the dynamic behavior of arrays of uncontrolled wave energy converters (WECs) in specific configurations, in order to quantify changes in the wave fields and absorbed power without active control. To maximize wave energy conversion, however, it is necessary to apply active control techniques to the WECs that conform the array. In this paper, we propose the application of decentralized model predictive control (MPC) to the elements of an array by considering each individual WEC as a subsystem. Each decentralized MPC optimizes the absorbed power of its own WEC under the same input and state constraints that a centralized MPC otherwise would.Index Terms-Model predictive control (MPC), point absorber, wave energy converter (WEC) arrays.

Model Predictive Control of a Wave Energy Converter with Discrete Fluid Power Power Take-Off System

“…Recently, WPEA's based on the idea of Model Predictive Control (MPC) have attained increasing focus from the wave energy research community, see e.g., [4][5][6][7][8][9][10][11], and initial results are encouraging: MPC may lead to increased energy output of a WEC compared to e.g., reactive control WPEA. In the early work of [4,6,8], a linear MPC has been developed and simulated on ideal PTO systems harvesting energy of point absorber WEC's.…”

“…Similar conclusions are drawn by [11], which demonstrates the potentials of MPC in a simulation study of a model-scale point absorber albeit unrealistic performance requirements for the PTO system are obtained due to the simplicity of the used PTO model. [10] reports a study of both a centralized MPC and decentralized MPCs applied to a small array of three WECs and concludes that MPC can improve the energy absorption compared to a linear fixed damping controller. In this work, the PTO force is assumed to be continuously controllable within upper and lower bounds.…”

An Analysis of the Potential Benefits of Centralised Predictive Control for Optimal Electrical Power Generation From Wave Energy Arrays

“…Decentralised control techniques for arrays have employed both optimal methods such as MPC [25] and standard methods such as suboptimal control [26]. Optimal centralised methods in which the whole array is controlled as one dynamic system, including the interdevice interactions, have included Galerkin control [27] and MPC [28].…”

A Study about Performance and Robustness of Model Predictive Controllers in a WEC System

“…Although, since the last decade, more complex controllers like MPC (model predictive control) are being employed. The interest in implementing MPCs in WEC systems is motivated by the need to increase the productive/economic viability of these systems; due to the fact that these controllers allow them to minimize mechanical fatigue in their structures (limiting the operating ranges) and to focus the control strategy on the maximization of the extracted power directly.Actually, several authors have developed predictive controllers for WECs [7][8][9][10][11][12][13][14][15][16][17]. These MPCs can be grouped according to the characteristics of the cost function optimized.…”

“…On one side, in [9][10][11]13,14], a reduced model was used for the design, which did not consider the dynamics of the radiation force. Meanwhile,in [7,8,12,13,[15][16][17], such dynamics were considered in the design model. Moreover, the previous works did not consider the dynamics of the power take-off system (PTO), neither in the evaluation, nor in the design of the MPCs.…”