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

The authors evaluate the potential of a brushless doubly fed generation system for wind power applications. A 1.5 kW proof-of-concept laboratory prototype is used to investigate the feasibility of the proposed variable-speed generation principle. Experimental results show that the prototype system can achieve high efficiency over a range of speeds. The system efficiencies achieved at the power levels considered compare favorably with conventional squirrel cage induction machines. It is experimentally demonstrated that the brushless double fed system achieves variable-speed operation with a power converter of reduced rating. For the prototype under consideration, a 2:1 speed range can be covered with a converter rated at approximately 25% of system capacity. While reactive power control can be realized with the proposed system, the magnitude is limited by the desired low converter rating. The prototype system is also shown to exhibit excellent output current waveforms