Situational Awareness and Control of Distribution Systems and Interaction with Transmission Systems

With the Kyoto and Paris climate agreements countries worldwide agreed to reduce their greenhouse gas emissions. As a consequence, renewable energy sources are introduced and power systems are facing new challenges. This paper gives a survey of the challenges occurring in distribution systems worldwide with a focus on their automation and control including situational awareness, monitoring and supervision. Through the first part, the paper discusses the changing framework for distribution systems, the current industry practices, future enhancements and available options. An overview of sensors, actuators, communication systems and control center functions required for observability and controllability is given. Further, notable research activities and pilot projects all around the world are introduced. Microgrids and so-called Smart Grids are particularly discussed and differences and similarities of the projects are indicated. Progressing beyond research towards industrial practice is only possible if driven by the markets or government legislation. Thus, an overview on market issues for future distribution grids is given and new market mechanisms and government regulations are critically evaluated. Changes in distribution systems will also impact their interaction with generators and transmission systems. The new responsibilities of distribution system operators and the need for advanced data exchange between distribution and transmission operators are discussed. Finally, an outlook is provided and challenges and opportunities of prospective distribution grids are summarized.