Power electronics applications in utility systems This article shows the application of power electronics in the operation of power systems. Major changes associated with the operation of power systems are related with deregulation and powerquality. The main objective of deregulation is to facilitate the development of a competitive electricity market. The main economic emphasis of a competitive market is to reduce the cost of electricity. A competitive market allows users to select the utility company or generator that will provide the electricpower supply. This is normally done based on the price and quality of service. The quality of service is basically a power quality problem, which is basically a technical issue while deregulation deals with the operation mode and principles of the complete power system. This article presents two new concepts that provide technical solutions to the new challenges imposed in power systems. These concepts are the flexible AC transmission system (FACTS) and the flexible, reliable and intelligent electric energy delivery system (FRIENDS). The implementation of these two new concepts in power system requires the development of high power compensators and controllers.