International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November -2013 ISSN 2229-5518 IJSER © 2013 http://www.ijser.org Sliding Mode Control of a Doubly- fed Induction Generator(DFIG) for Wind Energy Conversion System Mahmoud Zadehbagheri , Rahim Ildarabadi , Majid Baghaei Nejad Abstract— The wind energy usage is one of the most important renewable energy with economic justification in the world. Due to the growing needs to the electrical energy, increased environmental pollutions and limitation in the fossils power resources, using of this energy in the power industry is necessary and inevitable. The broad use of wind Turbines in the power systems have caused that this Turbines have a decisive rule in these systems. So because of the better power quality of the Variable speed wind turbines, they are more applicable than the constant speed Turbines. Nowadays Speed control in doubly fed Induction Generator (DFIG) because of the advantages such as: good quality control, high efficiency, Improving power quality, no need to the capacitor banks and cost affectivity are used to have more. This paper presents a speed control of one doubly fed Induction Generator according to the sliding mode controller with the use of simulation in the MATLAB/Simulink environment and the simulation gained results demonstrate the ability of the proposed control strategy. Index Terms— doubly fed induction generator (DFIG), Wind Farm, Variable speed wind turbine, Sliding mode control, power converter. ——————————  —————————— 1 INTRODUCTION t the present time many countries are using of the wind energy as a constant energy. The installed capacity at the wind power is more than 25 GW worldwide. The wind Turbines systems including of the wind Turbines with con- stant speed armed with one induction generator, variable speed armed with one squirrel cage induction generator and/or synchronous, variable speed with multi-pole perma- nent magnet synchronous generator and wind turbine with variable speed armed by Doubly fed induction generator (DFIG) which nowadays the most usage of the turbines in the wind farms are based on the Doubly fed induction generator for the reasons that they have some of the outstanding fea- tures such as the ability to produce different speed, the ability to control active and reactive power, improvement of power quality, reduce costs related to inverter, etc [1,2,3]. Variable speed in these turbines will make this ability in them that they can be in broader area of the winds and work in their maxi- mum efficiency. In this system will use of a wound-rotor in- duction generator that this wounded rotor connect to the net- work via the sliding rings to a converter machine and the sta- tor machine. One of the most important advantages of DFIG is that equipment of the power electronic is the only carrying a fraction of the total power around 20 to 30%, this means re- duction of losses and costs in the electronic power converter. In addition to the providing necessary conditions for electrical network a wind system control zone has duty to provide pos- sible maximum transferring wind energy in the best efficiency, in this regard different controlling methods has been pro- posed by the researcher[4,5]. In this article for the control of the speed of Doubly Fed Induction Generator from a sliding mode control has been used. Sliding mode control theory is proposed by Utkin at 1977, after that theoretical works and its applications from the sliding mode control have been devel- oped. Since one of the most important benefits of sliding mode control is the “robustness” and this method is a nonlin- ear control method, so this will be used in the systems which there are uncertainty. This uncertainty may be structural (pa- rameters uncertainty) and/or non-structural, for example is not modelled dynamics. In this control method stability will be gained by holding of states of the system on the sliding base[5,6,7]. This paper offers a control method for inverter machine in order to regulate active and reactive power’s been exchanged between machine and grid, in which the control of the active power is for the wind speed to be adapted in a wind energy inverter system and the control of the reactive power allows to reach a unity power factor between grid and stator. 2 OVERVIEW OF DOUBLY FED INDUCTION GENERATOR The tremendous progress in the field of development of the wind turbines in order to power production has been started since 1975. The first modern turbine was connected to the grid around 1980. With development of usage of the wind energy and wind power production DFIG is using widely nowadays. The reason which this type of generator is calling as doubly fed induction generator is that, the produced electrical power transfers by two ways, stator as well as rotor. These generators are at the especial attention because of their features which A ————————————————  Mahmoud Zadehbagheri is with the Hakim Sabzevari University, Faculty of Electrical Engineering, Sabzevar, Iran .(mahmood_zad@yahoo.com)  Rahim Ildarabadi is with the Hakim Sabzevari University , Faculty of Electrical Engineering, Sabzevar, Iran.( r.ildar@hsu.ac.ir).  Majid Baghaei Nejad is with the Hakim Sabzevari University , Faculty of Electrical Engineering, Sabzevar, Iran (mbnejad@hsu.ac.ir) 1573 IJSER