Plenary Lectures

Abstract

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 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 energy plants and the control problems involved and how control systems can help in increasing their efficiency. Some illustrative examples are given.

Short Bio

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).
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). Currently he is the 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, has been associate editor of the European Journal of Control until 2006 when he was promoted to editor at large 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 Control and Decision Conference and European Control Conference (CDC-ECC.05).

Abstract

Power system operation has traditionally relied upon generation manoeuverability for resolving generation-load imbalances. The variability inherent in renewable energy resources is, however, challenging that paradigm. Control of highly distributed loads may offer an alternative, with emerging communications platforms potentially able to monitor and issue control signals to distinct populations of loads. The presentation will consider the technical issues that must be addressed in order to achieve a fully responsive distributed load control scheme. It will identify requirements for measuring, modeling and controlling electrical demand to provide system services previously inaccessible by loads. The focus will be on direct load control schemes that aggregate thousands to millions of relatively small electrical loads. The presentation will review potential applications and benefits of distributed load control.

Short Bio

Ian A. Hiskens is the Vennema Professor of Engineering in the Department of Electrical Engineering and Computer Science at the University of Michigan in Ann Arbor. He has degrees in electrical engineering and mathematics, and obtained his Ph.D. degree from the University of Newcastle, Australia, in 1991. He has held prior appointments with the Queensland Electricity Supply Industry, Australia, from 1980 to 1992, the University of Newcastle, from 1992 to 1999, the University of Illinois at Urbana-Champaign, from 1999 to 2002, and the University of Wisconsin-Madison from 2002 to 2008.

Dr Hiskens' major research interests lie in the area of power system analysis, in particular system dynamics, security, and numerical techniques. Other research interests include nonlinear and hybrid dynamical systems, and control. He is actively involved in various IEEE societies, and is Treasurer of the IEEE Systems Council. He is a Fellow of the IEEE, a Fellow of Engineers Australia, and a Chartered Professional Engineer in Australia.

Abstract

The shift from traditional fossil fuels toward renewable and sustainable sources of electricity is one of the greatest global technological imperatives of the coming century. There is ample evidence today for the potential of renewable sources to help meet the world's growing demand for electricity: wind energy in particular is well-positioned to deliver renewable electricity in substantial quantities over the next 20 years. At the same time, renewable energy differs from fossil-fuel energy in that its scope for integration into the world's power systems is limited not so much by resource availability, as by the challenges of natural variability, grid adequacy and market efficiency: by questions of where, when, how and at what cost energy is delivered. The most immediate challenges arise from the fact that the most advantageous locations for renewable generators do not coincide with traditional generation sites, and require a new approach to the engineering of electricity networks that developed last century under very different assumptions. In the longer term, higher penetrations of renewable energy will challenge deeper traditional assumptions, such as that of a stark contrast between 'tractable generation' and 'intractable load'. Advanced engineering, in the form of new control methods and 'smart grid' technologies, already plays an important role in the evolution of electricity networks to accommodate a broader range of uses. This role is set to expand greatly in future as 21st-century power systems fulfil their dual role of attaining a diverse energy mix and maintaining stable and secure service to consumers.

Short Bio

Tony Morton is a Senior Engineer in Power Systems with Senergy Econnect, a specialist consulting firm providing engineering advice to the global energy sector. Tony's work with Senergy Econnect focusses on the integration of renewable energy into power grids and the sustainable utilisation of electricity. Tony gained his PhD in Electrical Engineering from the University of Melbourne in 2000 on the use of direct current in electrical installations. His research and consulting interests include power system modelling and control, power electronics, nonlinear system theory, wind and other renewable energy systems, and sustainable transport. His recent work includes feasibility, load flow and dynamic studies for small and large wind farm projects in Australia, New Zealand and the UK; the development of software for wind turbine dynamic models; and electrical engineering assistance to a variety of public and private sector clients. Tony's extensive publication record includes technical papers and specialist reports to Australian governments and agencies, dealing with the effective integration and network impacts of distributed and variable generators and other emerging technologies.