Direct Power Control of DFIG Used in Wind Energy Conversion System
K. Bedoud(1,2), T. Bahi(2), A. Rhif(3), H. Merabet(1)
1,2Research Center in Industrial Technologies CRTI, ex CSC, BP 64 Cheraga, Algeria.
2 Automatic Laboratory and Signals, Badji Mokhtar University, Annaba, Algeria
3 Laboratory of Advanced Systems (Polytechnic School of Tunisia)University of Carthage
*BEDOUD Khouloud: [email protected]
Abstract :
The problems caused by traditional systems on the environment of energy production have succeeded, in the immediate, the utilization the renewable energies for to preserve the environment and to satisfy the energy. So, thanks to the encouragement of governments and the global orientations, the development of wind energy has grown significantly due to the diversity of exploitable areas and to the relatively attractive costs. Therefore, the wind energy is becoming one of the most important renewable energy sources. Indeed, variable speed Wind Energy Conversion System (WECS) have become the industry standard because of their advantages over fixed speed ones such as improved energy capture, better power quality.
The WECS described in this work is show by figure 1. He includes the wind turbine, gearbox, DFIG, and back-to-back converters whereas the stator winding is fed by back-to-back bidirectional converter. In this system, the wind energy is transmitted Through the turbine to the three-phase DFIG. This energy is transmitted directly through a bridge rectifier and inverter to the electrical network.
Fig.1 Schematic diagram wind energy conversion system Wind turbine
Ωmec
Ωtur Pr
Gearbox
DFIG
Ps
Wind
AC/DC
AC-Electrical Network
DC/AC Rectifier Inverter
RSC Control algorithm
GSC Control algorithm
MPPT
Pa_ref
A DFIG consists of a wound rotor induction generator (WRIG) with the stator windings directly connected to a three-phase power grid and with the rotor windings mounted to a bidirectional back-to-back IGBT frequency converter. In order to control the active and reactive powers the Direct Power Control (DPC) is applied in this work
This paper presents the study of a variable speed wind energy conversion system using a Doubly Fed Induction Generator (DFIG) based on Direct Power Control applied to achieve control of active and reactive powers exchanged between the stator of the DFIG and the grid to ensure a Maximum Power Point Tracking (MPPT) of a wind energy conversion system.
Figure 2 shows the considered configuration of the direct instantaneous active power (Pa) and reactive power (Qa) controller. This control strategy contain the hysteresis comparators regulators where their inputs are the error signals between the active power reference (Paref) and the estimated active power (Pest) and between the reactive power reference (Qaref) and the estimated reactive power (Qest). The output signals CP and Cq of the comparators are defined based on an adequate algorithm. The switching table takes as input the errors Cp, Cq and the voltage vector position, the switching states Sa, Sb, and Sc of the converter are selected by this switching table defined previously.
Fig. 2. Scheme of control strategy
RSC
AC-Electrical Network
Filter
GRC
Mesure, Estimation and calculation
Vdc_ref
Switching Table
PI Controller Sector
Im_mac
Q_ref=0 Cp
re f
Cq re f
First, the model of the doubly fed induction generator is developed. After, the Direct Power Control of DFIG is presented and the performance of DPC are analysed. In last section the simulation results are shown and discussed. Results obtained in / environment shows that DPC can be used to regulate the active and reactive powers independently different speed wind and clearly indicate the effectiveness and validity of the proposed method.
Keyword:
Wind energy conversion system; Doubly Fed Induction Generator; Maximum power point tracking; Simulation
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