Offshore wind power is at an advanced point. Nowadays, there are large offshore wind farms planned or under construction, mainly in northern Europe. In addition, the floating platform development is a major research topic intended to facilitate the implementation of wind turbines in deep waters and remote areas of the coast. Moreover, marine energy is an enormous resource that can play a decisive role in the future to meet global energy needs. Development of systems for the extraction of power from sea currents (Seagen, Seaflow, Stingray, TidEL, ...), marine thermal power and wave energy (Pelamis, AWS, Wave dragon, Wave plane, OPT, WaveGen, Sperboy, ...) are under way. Most of these projects are in the prototype stage, rated at low power, and located very near from the shore. Despite its enormous potential, there is no draft of high-power marine parks far from the coast yet. However, it is expected that in the near future they will be implemented. In both cases, one of the most important technological barriers facing these technologies is the evacuation of power from the wind and/or marine farm at sea to the onshore grid connection. Traditionally, the transmission of energy from offshore wind has been done by high voltage AC (HVAC). However, as the parks are settled farther away from the coast and the length of the transmission lines increases, various technical problems appear including high consumption of reactive power due to increased parasitic capacitance of the cable, the larger energy losses of the cables, its higher cost, etc. All this leads that, for a particular offshore farm configuration and a certain distance (around 100 km), the energy transmission is technically and economically advantageous via high-voltage direct current (HVDC). This coordinated project intends to analyze a medium voltage DC transmission architecture for offshore applications. The main feature of this architecture lies in the fact that the AC to DC current transformation is not located in an offshore platform but it is distributed in each of the wind turbines. In this way it is possible to eliminate or, at least, significantly reduce the size of the offshore platform reducing the costs of the transmission system. According to an economic study that we have already done, the implementation of this decentralized architecture would improve the competitiveness of DC transmission systems for short distances. This would make feasible the use of this technology for most of the locations for offshore generation defined in the " Estudio Estratégico Ambiental del Litoral Español Del Ministerio de Medio Ambiente y Medio Rural y Marino". The project will involve two research groups, one of Tecnalia Research and Innovation and the other from the Universitat Politècnica de Catalunya (UPC), working in the following aspects: 1. Modeling, simulation, and development of control algorithms for the proposed medium voltage DC transmission system including both the offshore and onshore parts of the DC-link. Each of the research groups involved in the project is responsible for the analysis of these parts. The group from the UPC will be mainly involved in the development of control algorithms for the wind turbine generators in order to optimize the energy conversion efficiency, the characterization of the wind resource and the development of control strategies for the medium voltage DC/AC onshore grid-connected power converter. The group from Tecnalia Research and Innovation will be focused on the tasks related with the design of the medium voltage DC grid, the design of the DC filters to avoid electrical resonances in the DC grid and the development and control of the DC/DC wind turbine power converters needed to connect the turbines to the DC grid. 2. Experimental validation of the concepts evaluated in this project. A scaled-down experimental test bench to verify the performance of the studied concept will be built once the simulation analysis of the transmission architecture and power converters is completed. Here again, both research groups will work in complementary activities. One of them will develop and manufacture the offshore wind turbine power converters needed to connect each wind turbine to the medium voltage DC grid, will program the control algorithms of these converters and will develop a configurable platform able to reproduce different wind park electrical configurations (Tecnalia). The other group will assemble the onshore grid-connected converter and program the control algorithms for this converter and for the electrical generators (UPC). Finally, both research groups will work in the integration of the different converters in a common test bed.
Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008-2011
Proyectos de Investigación Fundamental
Proyectos de investigación fundamental no orientada
Proyectos de investigación fundamental no orientada. Àrea de Energías convencionales alternativas
Gobierno De España. Ministerio De Economía Y Competitividad, Mineco
Picas, R.; Ceballos, S.; Pou, J.; Zaragoza, J.; Konstantinou, G.; Agelidis, V. Annual Conference of the IEEE Industrial Electronics Society p. 6233-6238 DOI: 10.1109/IECON.2013.6700160 Presentation's date: 2013-11 Presentation of work at congresses