Abstract-As a result of increasing environmental concern, more and more electricity is generated from renewable sources. One way of generating electricity from renewable sources is to use wind turbines. A tendency to erect more and more wind turbines can be observed. Because of this, in the near future wind turbines may start to influence the behaviour of electrical power systems. Therefore, adequate models to study the impact of wind turbines on electrical power system behaviour are needed. The wind turbines can be operated in two modes: constant-speed and variable-speed. Squirrel Cage Induction Generator (SCIG) has been simulated that works in constant-speed operation. Doubly Fed Induction Generator (DFIG) that is used in a variable-speed turbine can be controlled in two ways. They can produce power with constant power factor or they control magnitude of voltage of PCC. PSCAD/EMTDC simulation program is used to investigate the impact of these turbines on a distribution grid. Each of these has different impacts on the distribution grids. All of above-mentioned methods are applied under same disturbances in wind speed in the simulation. This simulation is based on a vector control of the DFIG machine. The technique of vector control is used to control the output parameters of the rotor of DFIG in different loading conditions and variable rotor speeds. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation and control schemes. Also, it is shown that voltage control scheme has better results and improves the voltage profile considerably.Index Terms-DFIG, PSCAD/EMTDC, vector control, wind turbine.