T THE MICROGRID IS A CONCEPT FOR WHICH THE CONTROLLER IS THE DEFINING AND enabling technology. Indeed, the microgrid may be defined as the resources-generation, storage, and loads- within a boundary that are managed by the controller. The microgrid controller manages the resources within the microgrid's boundaries, at the point of interconnection with the utility and in interaction with the utility during normal operations (sometimes called cooperative control). It is at this level that the microgrid controller achieves its full potential for optimizing the value of distributed energy resources (DERs) for grid operations and customers, both those served by the microgrid directly and by the utility overall. The microgrid controller is what defines the microgrid's operational relationship with the distribution utility. This article focuses on R&D initiatives with respect to the evolution of microgrid controllers that the U.S. Department of Energy (DOE) Office of Electricity Delivery and Energy Reliability (DOE/OE) has undertaken since 2010. We describe demonstration projects that are planned to show the viability and value of controller technology to support the on-going and future deployment of DERs and microgrids. The DOE/OE's initiatives follow a deliberate and planned time line, as shown in Figure 1. Each of these initiatives is discussed in the context of the DOE/OE R&D to advance microgrid controller technology for microgrids that are remote and islanded, as well as interconnected and interactive with the distribution utility. Microgrid Controllers for the Advanced Microgrid Advanced Microgrid The term "microgrid" is broadly used today to refer to solutions for maintaining power supply in the event of outages caused by extreme weather events. This comes from thinking about a microgrid as a self-contained organization of DERs capable of islanding. This describes a microgrid whose purpose is strictly for resiliency with a control mechanism to simply open a switch to island. Microgrid Controller Initiatives By Dan Ton and Jim Reilly IMAGE LICENSED BY INGRAM PUBLISHING Digital Object Identifier 10.1109/MPE.2017.2691238 Date of publication: 16 June 2017 24 ieee power & energy magazine 1540-7977/17©2017IEEE july/august 2017