Wave-power absorption from a finite array of oscillating wave surge converters

Semi-analytical and fully numerical modelling is developed in the framework of the inviscid potential flow theory to investigate the dynamics of a wave farm made by flap-type wave energy converters in the nearshore. The hydrodynamic parameters and the efficiency of the system in typical layouts are calculated with both models. Good agreement is shown between the two approaches. Parametric analysis undertaken with the semi-analytical model allows to identify a near-resonant phenomenon which is responsible for increasing the absorbed power by the single elements of the array. Such result could be used as a preliminary design criterion. The numerical model is then applied to analyse a configuration of practical engineering interest, i.e. an array of two staggered converters. The dynamics arising in this more complex system is explained, showing that non-symmetric layouts can be less effective

Maximum power point tracking control of a linear magnetic-geared generator for direct-drive wave energy conversion

This paper deals with control of a linear magneticgeared permanent-magnet generator for wave power generation using maximum power point tracking (MPPT) algorithm. Firstly, the linear magnetic-geared permanent-magnet generator structure is presented. The machine modeling is established based on the finite element analysis (FEA). Secondly, by analyzing the dynamic model of the wave power, the MPPT algorithm for directdrive wave power generation is discussed. Then, the performance for maximizing wave power absorption is verified and evaluated by the circuit simulator. The results verify that the MPPT algorithm is valid for the direct-drive wave power generation.postprin

Complex-conjugate control of a linear magnetic-geared permanent-magnet machine for Archimedes wave swing based power generation

Paper no. YF-005177This paper deals with control of a linear magnetic-geared permanent-magnet machine for Archimedes wave swing based wave power generation using maximum power point tracking (MPPT). Firstly, the linear magnetic-geared permanent-magnet generator structure is presented. The machine modeling is established based on finite element analysis (FEA). Secondly, by analyzing the dynamic model of wave power, the MPPT algorithm for direct-drive wave power generation is developed. Then, the performance for maximizing wave power absorption is verified and evaluated by the circuit simulator. The results verify that the MPPT algorithm is valid for the direct-drive wave power generation. © 2015 IEEE.postprin

Perpendicular momentum injection by lower hybrid wave in a tokamak

The injection of lower hybrid waves for current drive into a tokamak affects the profile of intrinsic rotation. In this article, the momentum deposition by the lower hybrid wave on the electrons is studied. Due to the increase in the poloidal momentum of the wave as it propagates into the tokamak, the parallel momentum of the wave increases considerably. The change of the perpendicular momentum of the wave is such that the toroidal angular momentum of the wave is conserved. If the perpendicular momentum transfer via electron Landau damping is ignored, the transfer of the toroidal angular momentum to the plasma will be larger than the injected toroidal angular momentum. A proper quasilinear treatment proves that both perpendicular and parallel momentum are transferred to the electrons. The toroidal angular momentum of the electrons is then transferred to the ions via different mechanisms for the parallel and perpendicular momentum. The perpendicular momentum is transferred to ions through an outward radial electron pinch, while the parallel momentum is transferred through collisions.Comment: 22 pages, 4 figure

Quantification of the Prediction Requirements in Reactive Control of Wave Energy Converters

Optimal reactive control for maximum ocean wave power absorption from Wave Energy Converters (WECs) consisting of oscillating systems, is based on the principle of tuning their oscillation so that it is in resonance with the excitation force produced by the incident waves. Reactive control, however, is non-causal and cannot be implemented in real time. This paper analyses the prediction requirements of one possible solution, where predictions of the excitation force are utilised to resolve the non-causality. The study is focused on the analysis of the required forecasting horizon against the achievable prediction. Also, through the aid of numerical simulations of a number of specific systems over several wave conditions, a link is found between some fundamental properties of the system and the prediction requirements

Quantification of the Prediction Requirements in Reactive Control of Wave Energy Converters

Optimal reactive control for maximum ocean wave power absorption from Wave Energy Converters (WECs) consisting of oscillating systems, is based on the principle of tuning their oscillation so that it is in resonance with the excitation force produced by the incident waves. Reactive control, however, is non-causal and cannot be implemented in real time. This paper analyses the prediction requirements of one possible solution, where predictions of the excitation force are utilised to resolve the non-causality. The study is focused on the analysis of the required forecasting horizon against the achievable prediction. Also, through the aid of numerical simulations of a number of specific systems over several wave conditions, a link is found between some fundamental properties of the system and the prediction requirements