A stand-alone wind power supply with a Li-ion battery energy storage system

The improved structure of stand-alone wind power system which is presented in this paper based on a doubly fed induction generator (DFIG) and permanent magnet synchronous machine (PMSM). A Li-ion battery energy storage system is used to compensate the inherent power fluctuations (excess or shortage) and to regulate the overall system operation based on a power management strategy. The modeling and the control of a DFIG for stand-alone power applications are detailed. However, the magnitude and frequency of the DFIG stator output voltage are controlled under variable mechanical speed. This task is ensured via the control of d and q components of the rotor flux by means of a back-to-back pulse width modulation (PWM) converter connected to the rotor side of the DFIG. The PMSM is coupled mechanically to the wind turbine and supplies a required power to the PWM converter in order to regulate the dc bus voltage to the desired value.