Characteristics research of wind power generator interfaced to grid via solid state transformer with energy storage device

With the installed volume on wind farm increasing constantly, the impact of wind electricity on public grid has become increasingly evident, which superimposes more and more importance on the study on wind power integration to grid. A solid state transformer (SST) based induction wind power generator grid-connected system is put forward in this paper. The lumped parameter mathematical model of the induction wind power generator, input side controlled rectifier, output side inverter and middle stage high-frequency transformer are constituted respectively. System working principle at power flowing forward and backward status are analysed and the control strategy of each module is designed afterwards. A system simulation model is built based on topologies and control strategies discussed above. It is seen from the results that the newly designed system is of good working performance. The grid connecting current is sinusoidal and the unity power factor control is achieved. Output voltage and DC bus voltage are stable during the operating process. During voltage sag caused by grid faults, energy storage devices connected to the SST discharge to sustain the low-voltage DC bus voltage, enhancing the system low voltage ride through (LVRT) capability.