The use of renewable energy, such as solar energy, experienced a great impulse during the second half of the seventies just after the first big oil crisis. At that time economic issues were the most important factors and the interest in these types of processes decreased when the oil prices fell. There is a renewed interest in the use of renewable energies nowadays driven by the need of reducing the high environmental impact produced by the use of fossil energy systems. There are two main drawbacks of energy systems: a) the resulting energy costs are not yet competitive and b) solar energy is not always available when needed. Considerable research efforts are being devoted to techniques which may help to overcome these drawbacks, control is one of those techniques. A thermal solar power plant basically consists of a system where the solar energy is collected, then concentrated and finally transferred to a fluid. The thermal energy of the hot fluid is then used for different purposes such as generating electricity, the desalination of sea water etc. While in other power generating processes, the main source of energy (the fuel) can be manipulated as it is used as the main control variable, in solar energy systems, the main source of power which is solar radiation cannot be manipulated and furthermore it changes in a seasonal and on a daily base acting as a disturbance when considering it from a control point of view. Solar plants have all the characteristics needed for using advanced control strategies able to cope with changing dynamics, (nonlinearities and uncertainties). As fixed PID controllers cannot cope with some of the mentioned problems, they have to be detuned with low gain, producing sluggish responses or if they are tightly tuned they may produce high oscillations when the dynamics of the process vary, due to environmental and/or operating conditions changes. The use of more efficient control strategies resulting in better responses would increase the number of operational hours of the plants. The talk describes the main solar thermal plants, the control problems involved and how control systems can help in increasing their efficiency. Some illustrative examples are given.
Eduardo F. Camacho received his doctorate in Electrical engineering from the University of Seville where he is now a full professor of the Department of System Engineering and Automatic Control. He has written the books: Model Predictive Control in the Process industry (1995), Advanced Control of Solar Plants (1997) and Model Predictive Control (1999), (2004 second edition) published by Springer-Verlag, Control e Instrumentación de Procesos Quimicos published by Ed. Sintesis and Control of Dead-time Processes published by Springer-Verlag (2007) and Control of Solar Systems published by Springer Verlag (2011). He has served on various IFAC technical committees and chaired the IFAC publication Committee from 2002-2005. He was the president of the European Control Association (2005-2007) and chaired the IEEE/CSS International Affairs Committee (2003-2006), Chair of the IFAC Policy Committee and a member of the IEEE/CSS Board of Governors. He has acted as evaluator of projects at national and European level and was appointed Manager of the Advanced Production Technology Program of the Spanish National R&D Program (1996-2000). He was one of the Spanish representatives on the Program Committee of the Growth Research program and expert for the Program Committee of the NMP research priority of the European Union. He has carried out review and editorial work for various technical journals and many conferences. At present he is one of the editors of the IFAC journal, Control Engineering Practice, editor at large of the European Journal of Control and subject editor of the journal Optimal Control: Methods and Applications. He was Publication Chair for the IFAC World Congress b.02 and General Chair of the joint IEEE CDC and ECC 2005, and co-general chair of the joint 50th IEEE CDC-ECC 2011.
João Manuel Lage de Miranda Lemos