Marine Renewable Energy Converters and Biofouling: A Review on Impacts and Prevention

International audienceIn recent years, a number of studies have been performed to assess the damages caused by biofouling, which is simply the attachment of organisms to a surface in contact with water for a period of time. This explanation sounds fairly straightforward, but there are several organisms that cause biofouling, many different types of affected surfaces, and therefore many solutions dealing with this problem. Regarding the marine renewable energy emerging and promising area of research, this paper aims to provide a review of the biofouling issue in the context of Marine Renewable Energy Converters (MRECs). The proposed review will specifically highlight biofouling impacts on MRECs and solutions to prevent fouling. In addition, a discussion will highlight challenges that MRECs market needs to undertake to overcome the biofouling problem

Simplified Second-Order Generalized Integrator - Frequency-Locked Loop

Second-Order Generalized Integrator –Frequency-Locked Loop (SOGI-FLL) is a popular technique available in the grid synchronization literature. This technique uses gain normalization in the frequency locked-loop. This increases the computational complex-ity. In this paper, we propose an alternative imple-mentation to reduce the computational complexity of the SOGI-FLL. The proposed implementation modifies mainly the frequency locked-loop part and requires normalized voltage measurement. dSPACE 1104 board-based hardware implementation shows that the proposed implementation executes 20 % faster than the standard implementation. This could be very beneficial for high switching frequency application e.g. ≥ 1 MHz. In ad-dition to the nominal frequency case, multiresonant implementation is also proposed to tackle grid harmonics using a simpler harmonic decoupling network. Small signal dynamical modeling and tuning are performed for both implementations. Dynamical equivalence is also established between the two implementations. Experimental comparative analysis demonstrates similar or better performance (depending on test scenarios) with respect to the standard implementation of the SOGI-FL

Generator Systems for Marine Current Turbine Applications: A Comparative Study

Emerging technologies for marine current turbines are mainly related to works that have been carried out on wind turbines and ship propellers. It is then obvious that many electric generator topologies could be used for marine current turbines. As in the wind turbine context, doubly-fed induction generators and permanent magnet generators seem to be attractive solutions for harnessing the tidal current energy. In this paper, a comparative study between these two generator types is presented and fully analyzed in terms of generated power, maintenance, and operation constraints. This comparison is done for the Raz de Sein site (Brittany, France) using a multiphysics modeling simulation tool. This tool integrates, in a modular environment, the resource model, the turbine hydrodynamicmodel, and generator models. Experiments have also been carried out to confirm the simulation results.Financement de thèse de Brest Métropole Océan

An Up-to-Date Technologies Review and Evaluation of Wave Energy Converters

International audience– The potential of electric power generation from marine renewable energy is enormous. Ocean waves are being recognized as a resource to be exploited for the sustainable generation of electrical power. The high load factors resulting from the fluid properties and the predictable resource characteristics make ocean waves particularly attractive for power generation and advantageous when compared to other renewable energies. Regarding this emerging and promising area of research, this paper presents a complete review of wave energy technologies describing, analyzing and fixing many of the concepts behind wave energy conversion. The proposed review will specifically highlights the main wave energy conversion projects around the world at different levels (demonstration stage, in production, and commercialized projects). In particular, mooring will be discussed, as it is a key feature behind massive deployment of wave energy converters. Finally, a discussion will highlight challenges that wave energy converters need to overcome to become commercially competitive in the global energy market. Nomenclature WEC = Wave Energy Converter; PTO = Power TakeOff ; P w_f = Power per meter of wave front; P w_mcl = Power per meter crest length; ρ = Water density (approximately 1000 kg/m 3); g = Gravity acceleration; A = Wave amplitude; T = Wave period

Modeling and Control of a Marine Current Turbine Driven Doubly-Fed Induction Generator

This paper deals with the modeling and the control of a variable speed DFIG-based marine current turbine with and without tidal current speed sensor. The proposed MPPT control strategy relies on the resource and the marine turbine models that were validated by experimental data. The sensitivity of the proposed control strategy is analyzed regarding the swell effect as it is considered as the most disturbing one for the resource model. Tidal current data from the Raz de Sein (Brittany, France) are used to run simulations of a 7.5-kW prototype over various flow regimes. Simulation results are presented and fully analyzedThis work has been funded by Brest Métropole Océan

Modélisation et commande d’une hydrolienne équipée d’une génératrice asynchrone double alimentation

Cet article traite de la modélisation et de la commande d’un système de récupération de l’énergie des courants de marée ; à savoir une hydrolienne équipée d’une génératrice asynchrone double alimentation. Dans un premier temps et dans le but de pouvoir évaluer les performances et la dynamique de l’hydrolienne, dans différentes conditions de fonctionnement, un modèle multiphysique est implanté sous Matlab/Simulink®. Ensuite, une stratégie de commande MPPT sans capteur de vitesse de la génératrice asynchrone est proposée. Cette stratégie est éprouvée en regard de l’effet de la houle qui est considéré comme le plus à même de perturber le modèle de la ressource. La modélisation multi-physique et la commande à vitesse variable ont été testés sur une hydrolienne équipée d’une génératrice asynchrone double alimentation de 7,5 kW et en utilisant des données réelles du site du Raz-de-Sein (Bretagne) pour l’année 2007.Financement de thèse de Brest Métropole Océan

DFIG versus PMSG for marine current turbine applications

Emerging technologies for marine current turbine are mainly relevant to works that have been carried out on wind turbines and ship propellers. It is then obvious that many electric generator topologies could be used for marine current turbines. As in the wind turbine context, doubly-fed induction generators and permanent magnet generators seems to be attractive solutions to be used to harness the tidal current energy. In this paper, a comparative study between these two generators type is presented and fully analyzed in terms of generated power, maintenance and operation constraints. This comparison is done for the Raz de Sein site (Brittany, France) using a multi physics modeling simulation tool. This tool integrates, in a modular environment, the resource model, the turbine hydrodynamic model and the generators models