Renewable energy conversion systems (wind & photovoltaic)

Wind and photovoltaic grid-connected energy systems are the two fastest growing renewable energy sources of the last decade. This is due to cost reduction and the development of key technologies used in wind and photovoltaic energy systems, together with subsidies and environmental awareness. In addition, the cost increase of fossil fuels, their limited reserves and adverse impact on the environment, have contributed to the competitiveness and penetration of renewables to the grid. The interest in renewable energy systems and the search for more cost effective, efficient and reliable solutions has driven the industry towards larger wind turbines in the multimegawatt range, and utility-scale PV plants. This has been achieved mainly through economy of scale and higher energy conversion efficiency by research and development of new technology. In this respect, power converters and their control are key enabling technologies for renewable energy conversion systems. The inherent variable nature of wind and solar irradiation, the efficient operation of the conversion system following the maximum power point, and grid connection requirements (synchronization, power control and low voltage ride through), are some of the challenges addressed by the power converter and control system. At Powerlab research on both Wind and Photovoltaic energy conversion systems has been performed actively over the last years. The main focus has been the development of new multilevel converter interface systems to the grid, particularly oriented to large-scale high power systems. Several contributions have been made over the last years, including a boon on wind energy conversion systems.