  The smart grid revolution is creating a paradigm shift in distribution
networks that is marked by new, significant intermittencies and uncertainties
in power supply and demand. These developments include the dramatic increase in
the adoption of distributed energy resources (DER), electric vehicles, energy
storage, and controllable loads. This transformation imposes new challenges on
existing distribution infrastructure and system operations for stockholders,
engineers, operators and customers. Unfortunately, distribution networks
historically lag behind transmission networks in terms of observability,
measurement accuracy, and data granularity. The changes in the operation of the
electric grid dramatically increase the need for tools to monitor and manage
distribution networks in a fast, reliable and accurate fashion. This paper
describes the development process of a network of high-precision micro phasor
measurement units or uPMUs, beginning with an overview of the uPMU technology
that provides synchronous measurements of voltage phase angles, or
synchrophasors. Next, the uPMU network and communications infrastructure are
discussed, followed by an analysis of potential diagnostic and control
applications of uPMU data in the electric grid at the distribution level.
