Doubly Fed Induction Generator-A Wind Technology in the Power System

As the stocks of conventional fuels are limited, their prices are increasing every day. The use of conventional fuels creates the problem in emission of greenhouse gases followed by global warming. At the same time the growing industrialization and modernization demands more electricity. Increased demand of electricity makes it necessary to go for alternative sources of energy like solar and wind. The potential of wind energy has made its power plant installation worldwide but along with conventional generation. The wind generators operate very differently from traditional generators. Their share in the power system is considerable, that forces us to study interaction between power systems and wind power plants and study how power system performs along with wind energy conversion systems. Though wind is great natural source speed unpredictability is a major challenge. So, technologies evolved as constant speed and variable speed wind turbines. The paper explains various types of wind energy conversion systems using squirrel cage induction generator (SCIG), synchronous generator (SG) and doubly fed induction generator (DFIG) and explains how they can be used as constant speed and variable speed systems. The paper also describes popularly used DFIG for adjustable speed operation. When DFIG based wind generation is included in power network on a large scale there is a need to control the power that is supplied by wind power plant to grid. These generators should be capable of controlling and regulating the power. There are many issues of concern like stability, power quality which are being researched. So, a DFIG model in simplest form is also described with its equivalent network.