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Unformatted text preview: 1 Chapter 5 WIND ENERGY CONVERSION SYSTEM 5.1 Introduction Wind energy systems have been used for centuries as a source of energy for mankind. Windmills were deployed for pumping water in China several centuries B.C. It is reported that vertical-axis windmills equipped with woven reed sails were used for grinding grains in the Middle East and Persia in 200 - 100 B.C. The use of windpower was introduced to Europe in the 11th century. During the early stages of European industrial revolution, significant activities in innovative windmill designs of windmills had taken place. By the end of the 14th century the Dutch had improved windmill designs and made extensive use of windmills to drain marshes of the Rhine delta. Between the mid-19 th century to the mid-20 th century more than 6 million small windmills (less than one horsepower each) were built and instlled in the United States to pump water and generate electricity. By the end of the 19th century there were about 3000 industrial windmills and about 30,000 other types used for homes and farms in Denmark. Until the 1970's the primary use of windmills in the United States was for water pumping and distributed stand-alone generation of electricity in cattle ranches. The significant exception was the utility-interactive 1250 kW Smith-Putnam wind turbine generator (WTG) that operated in Vermont from 1941 to 1945. So, there was a tremendous boost in capacity when multimegawatt machines were built in the United States starting in the late1970's. During this time frame, large scale WTG developments in the United States happened under the joint sponsorship of the Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA) which produced prototype machines whose capacities ranged from 100 kW to 4000 kW. Apparently these development projects raised more questions than they answered, and the attempts to commercialize the multi-megawatt WTG's were not successful. During the late 80’s and early 90’s, the focus in the United States and elsewhere had been to limit the size of WTG's to a few hundred kilowatts. U.S. and Danish wind turbine generators (WTG's) of several hundred kilowatt capacity are were widely deployed for commercial scale 2 utility grid-connected applications. Beginning in the late 90’s and they early 2000’s there was again new focus on multi-megawatt WTG’s which formed the backbone of the European activity, and resulted in thousands of machines deployed in northwestern Europe and on the Mediterrnean coast. Beginning in the mid to late 2000’s there have been widespread applications of WTG’s in the United States, Germany, Spain, India and China. This chapter is devoted to the discussion on wind energy conversion systems (WECS) which includes the WTG, tower, speed control mechanism, and the associated electrical interface. In this connection we will discuss the types of rotors and electrical generators (collectively called the WTG) that are available and appropriate for different...
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This note was uploaded on 03/16/2012 for the course ECE 5374G taught by Professor Srahman during the Spring '12 term at Virginia Tech.

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