Dynamic Performance of Stand-Alone Wind-Driven Single Machine-Brushless Double Fed Generator

In this paper the dynamic performance of a stand-alone wind-driven Single Machine-Brushless Double Fed Generator (SM-BDFIG), supplying different loads in remote area is investigated. The battery embedded in the frame of the specially designed SM-BDFIG is used for energy storage in the super synchronous range of operation. The stored energy is used to supply enough slip power for the rotor circuit of the generator in the sub-synchronous range of operation, to feed the rotor with the necessary DC power at synchronous speed, and also to supply the priority loads at low wind speeds equal or below the cut-in speed. A programmable logic controller (PLC) is designed to control the operation of the rotor converters according to the wind speed and to manage the whole stand-alone system. The dynamic performance of the generator at variable wind speeds is studied. The effect of varying loads on the generator currents, voltages, and electromagnetic torque are given for variable wind speeds. Also the effect of sudden change in the wind speed on the SM-BDFIG performance is investigated. The investigation is done at synchronous speed as well as sub-synchronous and supersynchronous speeds. Results proved the stable operation of the proposed machine as generator at within the whole speed range (from sub-synchronous speed to super-synchronous) stably.