The electric power system is facing increasing stress due to fundamental changes in both supply and demand technologies. On the supply side, there is a shift from large synchronous generators to lighter-weight generators (e.g., gas-fired turbines) and variable resources (renewables). On the demand side, there is a growing number of distributed and variable generation resources as well as a shift from large induction motors to rapidly increasing use of electronic converters in buildings and, industrial equipment. The communications and control systems are also transitioning from analog systems to systems with increasing digital control and communications; from systems with a handful of control points at central stations to ones with potentially millions of control points.

With these and other changes, the system is being asked to perform in ways and in a context for which it was not designed. The result is a system that is under increasing stress from these and other factors and requires much greater flexibility, agility, and ability to dynamically optimize grid operations in time frames that are too fast for human operators. Fundamental advances in the power system are needed to address these changes and ensure system reliability.  These changes, however, also open a set of opportunities that can be tapped to significantly improve performance, lower costs, and address our national energy challenges. The research needs that can help realize these opportunities are described in this chapter.