Decoupled Active and Reactive Power Control of a Doubly-Fed Induction Generator (DFIG) A. Dendouga , R. Abdessemed, M. L. Bendaas and A. Chaiba * LEB-Research Laboratory, Department of Electrical engineering, Batna University, Algeria E-mail : hakimdendouga@yahoo.fr Abstract— In This paper a decoupled control of a doubly- fed induction machine used in generation mode (DFIG) is presented. It provides decoupled regulation of the primary side active and reactive power and it is suitable for both electric energy generation and drive applications. The mathematical model of the machine written in an appropriate d-q reference frame is established to investigate simulations. In order to control the power flowing between the stator of the DFIG and the network, a decoupled control of active and reactive power is synthesized using PI controllers. Their respective performances are in terms of stator currents references tracking. Mots clefs — DFIG, active and reactive power, decoupled control, robustness. I. INTRODUCTION A vector controlled techniques of a Doubly-Fed Induction Generator (DFIG) is an attractive solution for high performance restricted speed-range electric drives and energy generations applications [1, 2, 3]. Fig.1 reports the typical connection scheme of this machine. This solution is suitable for all of the applications where limited speed variations around the synchronous speed are present. Since the power handled by the rotor side (slip power) is proportional to slip, an energy conversion is possible using a rotor-side power converter, which handles only a small fraction of the overall system power. Moreover, if suitable controlled AC/DC/AC converter is used to supply the rotor side, the power components of the overall system can be controlled with low current harmonic distortion in the stator and rotor sides [4,5]. The classical approach for DFIG vector control [2] requires measurements of stator, rotor currents and rotor position. In order to achieve synchronization with line voltage vector for soft connection to the line-grid the information about line voltages is additionally needed. Exact knowledge of induction machine inductances (including saturation effect) is required to compute fluxes from currents. In this work, the approach for the design of DFIG active-reactive power control is proposed. Both controllers are developed in a line-voltage oriented reference frame. Since the line voltage vector can be easily measured with negligible errors, this reference frame is DFIG parameter invariant in contrast to the field oriented one. Moreover, information about line voltage is typically needed in order to perform the soft connection of the DFIG to the line grid during preliminary excitation-synchronization stage [5]. The aim of this paper is to introduce a new decoupled control algorithm of the DFIG active and reactive power. It is shown that direct closed loop control of active and reactive power guarantees global asymptotic regulation of output variables, under condition of measurable stator currents, voltages and rotor position and speed. In addition, owing to the closed loop structure with true- stator-current feedback signals, the controller compensates the non-idealities of electric machine magnetic structure, delivering improved stator current waveforms. II. DFIG MODEL AND CONTROL OBJECTIVES Under assumption of linear magnetic circuits and balanced operating conditions, the equivalent two-phase model of the symmetrical DFIG, represented in an arbitrary rotating (d-q) reference frame is: ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎩ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎨ ⎧ − = ω ω ω + ψ + = ψ ω ω − ψ + = ψ ω + ψ + = ψ ω − ψ + = ] r C e C [ J 1 rd ) - s ( dt rq d rq i r R rq v rq ) - s ( dt rd d rd i r R rd v sd s dt sq d sq i s R sq v sq s dt sd d sd i s R sd v & (1) Converter AC/AC Control DFIG Figure 1. Typical connection scheme of a DFIG. Line Grid Mechanical Load or Mover P s Q s 3URFHHGLQJV RI WKH WK 0HGLWHUUDQHDQ &RQIHUHQFH RQ &RQWURO  $XWRPDWLRQ -XO\     $WKHQV  *UHHFH 7