Development of a variable-speed, doubly-fed wind power generation system

Abstract

Generation of electricity from the wind is becoming increasing popular as an environmentally responsible resource. Current methods for generating electricity from the wind involve the use of fixed-speed generators. However, the use of variable-speed generators increases the amount of energy that can be extracted from the wind. Most variable-speed technologies require processing large amounts power electronically. In large utility-scale generation systems the added cost of the power electronics may make variable-speed generation too expensive. A reduction in the size of the power electronics is achieved when using the brushless doubly-fed machine. A proof-of-concept system has been developed to evaluate not only the advantages of variable-speed technology, but the advantages of using the brushless doubly-fed machine. The prototype system uses a two-bladed turbine with a diameter of 2.75 meters. The prototype system produces a maximum of 1500 watts in wind speeds ranging from 0 to 40 miles per hour. Experimental data illustrates the performance of the machine over a wide range of power levels. The machine exhibits satisfactory efficiency. Experimental results show that converter rating of the prototype system is one-fifth of that of a conventional variable-speed system. The proof-of-concept system shows that the brushless doubly-fed machine has superior features as compared to other systems. Future research needs to evaluate its use in a utility-scale environment.