Control strategy of wide-speed-range doubly fed induction generator based on stator-winding short circuited in low speed mode

When the doubly-fed induction generator (DFIG) is acting as a generator, for its limit of the power electronic converter rating, making the DFIG can only work at the speed of the range of the synchronous speed plus or minus 30%
^[1]
. So, when wind speed is low, the DFIG cannot work as a generator. This paper adopts a combinatorial topology which is wide-speed-range DFIG (WDFIG). If the wind speed is low, the stator-winding of DFIG is short circuited
^[2]
·
^[3]
, and the stator flux of DFIG is controlled by rotor side converter (RSC) also generating to grid through rotor side converter. If the wind speed is high, the stator-winding of DFIG which is short circuited become connecting to the power grid directly, and its architecture is same as the traditional architecture. In this paper, DFIG simplified mathematical model is first displayed and the method of stator-flux-oriented vector control (SFOVC) is adopted, then this paper displayed the simplified mathematical model of the two topology in d-q synchronous rotating reference frame, on that basis, deducing the control equation. Meanwhile, in order to guarantee the uninterruptible operating of the system, and avoid the lash such as flux, current, voltage and so on when the structure of the stator-winding of DFIG change from short circuited mode to grid connected mode. This paper gives theoretical analysis for the suitable switching moment, that ensure the variation range of flux, current, voltage during the switch moment are within bounds. At last, the simulation results proved that the proposed control architecture could ensure the DFIG work as a generator no matter wind speed is low or high.