Due to the increasing number of wind power plants all over the world, many studies have been carried out to assess the interaction of such plants with the distribution grid. In this context, this paper presents investigations in the design of wind turbine control systems to maximize the energy capture and their impact onto the grid. The modeling of the wind turbine is presented. Then three different speed control systems are detailed and evaluated through simulations carried out with Matlab Simulink TM. Power fluctuations on the distribution grid are then compared by considering the same wind speed fluctuations.