Horizontal axis wind turbines are by far the most common and well understood forms of wind turbine. Typically a large amount of research and development has been invested in the technology of large scale wind turbines. Unfortunately, development of small machines (rotor diameter smaller than 10 metres) has not been as forthcoming. The advantages of small turbines are that they are accessible to the individual consumer and they are a very attractive project for the home builder. The disadvantage of small turbines is that due to the negative influence of economies of scale, they tend to be costly in relation to their power output and suffer from a long-term return on investment. Furthermore, trends in the wind industry have shown that smaller machines tend to be relatively simple devices that have been developed with very little research and development. As a result, small turbines can be inefficient, unreliable and expensive to maintain. In many cases rotor design is less than optimal, with very little blade refinement. This is especially critical for small rotors due to low Reynolds Number operation. Further exacerbating the problem is that the rotors are typically not well matched to the generator. In many cases the machines are not suited to the wind speed range in which they are designed to operate, reducing the financial viability due to poor performance. It is envisaged that by applying optimising techniques and automating some of the design complexities into a software design tool, more cost-effective and viable machines can be developed that will deliver improved performance and therefore become more financially viable.

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Thesis (MTech(Electrical Engineering))--Cape Technikon, Cape Town,1995 / This thesis describes the research, development and design of one of the most modern generic control and automation system for mini Hydro turbines available in the world. Special emphasis is placed on the Man machine interface. A concept of total dynamic plant and data status representation was pursued. To achieve this, a large amount of graphical animation was incorporated into the design. The end product was to be the most economical and cost effective implementable design available , yet providing the most modern functions and features available in the world market. The system was developed and researched to be generic and applicable to any small Hydro plant. The design can thus be implemented on any suitable PLC and SCADA system and is not dependant on any specific manufactures hardware or software. The main emphasis is laid on functional capability of the design. Utilising this design standard would virtually cut the cost of engineering associated with the design of a Hydro control system by 90%. The design and engineering costs related to a Hydro automation project could typically exceed R 100 000 a for small Hydro plant as this scheme.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Microfiche copy available in Archives and Engineering. / Bibliography: leaf 149. / M.S.

This thesis presents and examines the concept that the output of a wound-rotor induction generator (WRIG) can be limited by means of linking to external impedances for wind-turbine generating system application. An 80kW-WRIG is simulated as a model to examine the control of the output power vs. speed characteristic. Model of WRIG derived from per phase equivalent circuit is organized, then it is estimated how much external impedances affect the characteristic of output power for it to approach to a typical wind-turbine curve. Practical tests are performed using 80kW-WRIG in testing lab to validate the simulation data. In addition, a smaller WRIG, connected on same shaft as 80kW-WRIG, is designed to extend the range of wind speed. Also external impedances with smaller WRIG are chosen to extract optimum power from wind-turbine. Finally, passively controlled tandem WRIGs are shown to have the capability to optimize wind-turbine energy extraction when controlled entirely by external impedances. / Graduation date: 2003

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Study and experiment indicate that, with existing technology, a modified open Brayton cycle can be used to burn common municipal refuse at atmospheric pressure and produce useful power while scrubbing the combustion product gases to remove pollutants.The hot combustion gases pass from a combustor through a turbine to a region below atmospheric pressure where they are scrubbed and cooled by mixing with water spray. The water spray and gas mixture is then exhausted to atmospheric pressure through a compressor.Although current compressor designs are workable in this application, a new design is needed which will have reduced water drag power loss.Ball State UniversityMuncie, IN 47306