This lecture will present the power quality problem associated with power electronic converters, discuss the applicability of the international standards and the new power electronics technologies that allow to minimize the problems caused by the power processing. It will have a tutorial format, including recent research results obtained by the author or available in the literature. Owing to the importance of the power quality for all equipment connected to the power grid, an overview of the state of the art in the power electronics field is an important background for electric and electronic engineers.