26-04-2012, 03:14 PM
Doubly-fed Induction generators for wind power generation
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INTRODUCTION
IN recent past much attention has been placed on the wind power generation. The installed capacity of the wind power in the world is now reaching 75 GW. Many countries have published their generation targets for 2010 or 2020. Among the different generators available for wind power generation, the Doubly-Fed Induction Generator (DFIG) has become the major competitor. Although many articles are available on DFIG generators and related control [1, 2, 3, 4], the authors have found that much difficulties still persist for a layman in understanding the concept. The natural result is that the stake holders of the wind industry have poor background on the basic concepts. Thus this paper presents the basic theory behind the DFIG operation and control from its first principles, and move further to explain the systems that are being implemented so far.
CASE STUDY
A 2 MW DFIG based wind turbine connected to an infinite bus through a transformer was modeled using PSCAD/EMTDCTM simulation environment. Data for the machine is given in the Appendix.
CONCLUSION
The paper presents the overview of the operation and control of a DFIG. The functionality of DFIG arrangement and controls for the maximum power extraction and reactive power control have been discussed from first principles so that stake holders of wind industry can understand them. The compensation required for de-
coupled control of two controllers is demonstrated with mathematical model and simulations. It was demonstrated that de-coupling allows d-axis controller to act for a step change without changing q-axis output. Further a case
study was used to demonstrate the overall operation of the controllers.