Smart Grid and Renewable Energy, 2010, 1, 119-131 doi:10.4236/sgre.2010.13017 Published Online November 2010 (http://www.SciRP.org/journal/sgre) Copyright © 2010 SciRes. SGRE 119 Wind Energy Conversion System from Electrical Perspective —A Survey Hyong Sik Kim, Dylan Dah-Chuan Lu School of Electrical and Information Engineering, University of Sydney, Sydney, Australia Email: hkim4210@uni.sydney.edu.au Received October 20 th , 2010; revised November 14 th , 2010; accepted November 20 th , 2010 ABSTRACT This paper focuses on the wind energy conversion system (WECS) with the three main electrical aspects: 1) wind tur- bine generators (WTGs), 2) power electronics converters (PECs) and 3) grid-connection issues. The current state of wind turbine generators are discussed and compared in some criteria along with the trends in the current WECS mar- ket, which are ‘Variable Speed’, ‘Multi-MW’ and ‘Offshore’. In addition, the other crucial component in the WECS, PECs will be discussed with its topologies available in the current WECS market along with their modulation strategies. Moreover, three main issues of the WECS associating with the grid-connection, fault-ride through (FRT) capability, harmonics/interharmonics emission and flicker, which are the power quality issues, will be discussed due to the in- creasing responsibility of WECS as utility power station. Some key findings from the review such as the attractiveness of BDFRG are presented in the conclusion of this paper. Keywords: Wind Energy, Wind Turbine Generators, Power Electronic Converters, Grid-Connection, Brushless, Reluctance, Pulse-Width Modulation, Fault Ride Through Capability, Voltage Dip, Harmonics, Flicker, Power Quality, BDFRG 1. Introduction Green house gas reduction has been one of the crucial and inevitable global challenges, especially for the last two decades as more evidences on global warming have been reported. This has drawn increasing attention to renewable energies including wind energy, which is re- garded as a relatively mature technology [1]. It recorded 159 GW for the total wind energy capacities in 2009, which is the highest capacity among the existing renew- able energy sources with excluding large-scale hydro power generators as shown in Figure 1 [2]. Also, its annual installation growth rate marked 31.7% in 2009 with its growth rate having been increasing for the last few years, which indicates that wind energy is one of the fastest growing and attractive renewable en- ergy sources [3]. The increasing price-competitiveness of wind energy against other conventional fossil fuel energy sources such as coal and natural gas is another positive indication on wind energy [4]. Therefore, a vast amount of researches on WECS have been and is being under- taken intensively. WECS consists of three major aspects; aerodynamic, mechanical and electrical as shown in Figure 2. The electrical aspect of WECS can further be divided into three main components, which are wind turbine generators (WTGs), power electronic converters (PECs) and the utility grid. There are many review papers on those electrical as- pects available; however, there seem small amount of investigation and discussion on some newer concepts of Figure 1. World renewable energy capacities in 2009 (based on [2]).