Physical power system strongly interacted with primary energy, environment, power market, infrastructure and many technique support systems etc., therefore obstruction in any linkage could introduce generalized congestion. Countermeasures are conceived by various experts to manage the congestions. Different emphases on the middle objective introduce confusion of the name; however, there are no big differences in their views on the final targets. It is better to view a smart grid as a vision one, but not a fixed criterion. The ¡°smartness¡± of a grid can be assessed by a non-negative index, which is composed of as many items as needed to adapt the further evolvement of requirements. This presentation discusses the relevant problems and concludes that smart grids are system engineering of multi-discipline and multi-system.

Professor Yusheng XUE became a member of Chinese Academy of Engineering in 1995. He has been Chief Engineer at the Nanjing Automation Research Institute (NARI), China since 1993. He is a member of the specialist team of State Grid Corporation of China and that of China Southern Power Grid. He is an honorary professor of the University of Queensland, Australia and Chairman of Technical Committee of Chinese National Committee of CIGRE.