Reactive power control strategy for a wind farm with DFIG

Reactive power control strategy for a wind farm with a doubly fed induction generator (DFIG) is investigated. Under stator flux-oriented (SFO) vector control, the real power of the DFIG is controlled by the q-axis rotor current I-qr and the reactive power is mainly affected by the d-axis rotor current I-dr To examine the effect of I-dr on stator reactive power Q(s) and rotor reactive power Q(r), the DFIG is operated under five different operating modes, i.e, the maximum Q(s) absorption mode, the rotor unity power factor mode, the minimum DFIG loss mode, the stator unity power factor mode, and the maximum Q(s) generation mode. In pervious works, stator resistance R-s was usually neglected in deriving the d-axis rotor currents I-dr for different DFIG reactive power operating modes. In the present work, an iterative algorithm is presented to compute the d-axis rotor currents I-dr for the five reactive power control modes. To demonstrate the effectiveness of the proposed iterative algorithm, the rotor current, rotor voltage, stator current, real power and reactive power of a 2.5 MW DFIG operated under the five different operating modes are computed. (C) 2016 Elsevier Ltd. All rights reserved.