This paper, prepared by a special task force of the IEEE PES Renewable Technologies Subcommittee, is a review of hybrid renewable/alternative energy (RE/AE) power generation systems focusing on energy sustainability. It highlights some important issues and challenges in the design and energy management of hybrid RE/AE systems. System configurations, generation unit sizing, storage needs, and energy management and control are addressed. Statistics on the current status and future trend of renewable power generation, as well as some critical challenges facing the widespread deployment of RE/AE power generation technologies and vision for future research in this area are also presented. The comprehensive list of references given at the end of the paper should be helpful to researchers working in this area.

A Review of Hybrid Renewable/Alternative Energy Systems for Electric Power Generation: Configurations, Control, and Applications

This book presents the papers given at a workshop on wind turbines. Topics considered at the workshop included aerodynamics, load conditions, Darrieus rotors, composite materials, turbine blades, fabrication, fiberglass, vibrations, wind power plants, control systems, data acquisition systems, performance testing, horizontal axis turbines, vertical axis turbines, tornado turbines, electric generators, and wind turbine arrays.

Wind energy systems

The Climate Near the Ground

A review on the complementarity of renewable energy sources: Concept, metrics, application and future research directions

Grid connection of renewable energy sources is essential if they are to be effectively exploited, but grid connection brings problems of voltage fluctuation and harmonic distortion. In this paper, appropriate modeling and simulation techniques are discussed for studying the voltage fluctuation and harmonic distortion in a network to which variable speed wind turbines are connected. Case studies on a distribution network show that the voltage fluctuation and harmonic problems can be minimized with the proposed power electronics interface and control system while the wind energy conversion system captures the maximum power from the wind as wind speed varies. The studies have also demonstrated the ability of the advanced converter to assist the system voltage regulation.

Grid Power Quality with Variable-Speed Wind Turbines

Economic and geopolitical constraints on global nonrenewable energy supplies will force many nations, especially the developing countries, to accelerate their use of local renewable energy sources. This paper discusses some of the technical, economic, and socioeconomic aspects of the application of renewable (solar) energy sources for rural development in resource-poor population-rich developing countries. The possible role of educational institutions in the U.S. and in the developing countries in assisting in the successful introduction of solar technologies in rural areas is outlined. A selected bibliography is included for the benefit of readers interested in additional information on this important topic.

Renewable Energy Sources and Rural Development in Developing Countries

Reliability analysis of combined wind-electric and conventional generation systems

A method of converting organic materials into useful products and disposable waste including the steps of shredding the organic material into particles, mixing the organic particles with water to obtain a pumpable slurry, raising the temperature and pressure of the slurry to about 300° to 500° C. and about 8000 to 12,000 psig in a reaction vessel to cause the slurry to hydropyrolyize, separating the products of hydropyrolysis to remove gases from the liquids and solids, separating the liquids and solids, treating the separated gases and liquids to extract hydrocarbon components therefrom and using the solids as fuel directly.

Method of converting organic material into useful products and disposable waste

The thesis of this paper is that the long-range solution to the energy woes of the world does not lie in any one particular approach and that several avenues should be explored simultaneously, with particular emphasis on the exploitation of solar energy in its various manifestations such as heat, winds, tides, and ocean thermal gradients. Research and development over the past thirteen years at Oklahoma State University has resulted in the evolution of several components required to engineer a continuous duty power system running on nonexpendable energy sources, namely the sun and the wind. This paper presents the system and discusses its applicability to the energy systems of the future.

Solar energy conversion and storage systems for the future

Wind farm power control is key to reliable large-scale wind integration. The design of a sophisticated wind farm controller, however, is challenging partly because there is a lack of models that appropriately simplify the complex overall dynamics of a large number of wind turbine control systems (WTCSs). In this paper, using system identification approaches, we develop a simple approximate model that attempts to mimic the active and reactive power dynamics of two generic WTCS models under normal operating conditions: an analytical model described by nonlinear differential equations, and an empirical one by input-output measurement data. The approximate model contains two parts-one for active power and one for reactive-each of which is a third-order system that would have been linear if not for a static nonlinearity. For each generic model, we also provide an identification scheme that sequentially determines the approximate model parameters. Finally, we show via simulation that, despite its structural simplicity, the approximate model is accurate and versatile, capable of closely imitating several different analytical and empirical WTCS models from the literature and from real data. The results suggest that the approximate model may be used to facilitate research on wind farm power control.

R. Ramakumar

Papers

Renewable Energy Sources and Rural Development in Developing Countries

Reliability analysis of combined wind-electric and conventional generation systems

Method of converting organic material into useful products and disposable waste

Solar energy conversion and storage systems for the future

An Approximate Wind Turbine Control System Model for Wind Farm Power Control