The advanced microgrid. Integration and interoperability

This white paper focuses on “advanced microgrids,” but sections do, out of necessity, reference today’s commercially available systems and installations in order to clearly distinguish the differences and advances. Advanced microgrids have been identified as being a necessary part of the modern electrical grid through a two DOE microgrid workshops, 1 ’ 2 the National Institute of Standards and Technology, 3 Smart Grid Interoperability Panel and other related sources. With their grid-interconnectivity advantages, advanced microgrids will improve system 4 energy efficiency and reliability and provide enabling technologies for grid-independence to end-user sites. One popular definition that has been evolved and is used in multiple references is that a microgrid is a group of interconnected loads and distributed-energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid. A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island-mode. Further, an advanced microgrid can then be loosely defined as a dynamic microgrid. The value of microgrids to protect the nation’s electrical grid from power outages is becoming increasingly important in the face of the increased frequency and intensity of events caused by severe weather. Advanced microgrids will serve to mitigate power 1 “DOE Microgrid Workshop Report,” Office of Electricity Delivery and Energy Reliability Smart Grid R&D Program, http://energy.gov/oe/downloads/microgrid-workshop-report-august-2011, Aug 2011. 2 “DOE Microgrid Workshop Report,” Office of Electricity Delivery and Energy Reliability Smart Grid R&D Program, http://energy.gov/oe/downloads/2012-doe-microgrid-workshop-summary-report-september-2012, Sep 2012. 3 SGIP webpage for applicable Smart Grid Interconnections, http://www.sgip.org/#sthash.6Gcyft6W.dpbs. 4 “DOE Microgrid Workshop Report,” Office of Electricity Delivery and Energy Reliability Smart Grid R&D Program, http://energy.gov/oe/downloads/2012-doe-microgrid-workshop-summary-report-september-2012, Sep 2012. disruption economic impacts. 5 Advanced microgrids will contain all the essential elements of a large-scale grid, such as the ability to (a) balance electrical demand with sources, (b) schedule the dispatch of resources, and (c) preserve grid reliability (both adequacy and security). In addition to these basic features, an advanced microgrid will also be able to interact with, connect to, and disconnect from another grid. An advanced microgrid is aptly named “micro” in the sense that a power rating of 1 MW (plus or minus one order of magnitude) is approximately a million times smaller than the U.S. power grid’s peak load of 1 TW. Some of the complexities required for a large grid such as complicated market operation systems, state estimation systems, complex resource commitment, and dispatch algorithms will be simplified. New advanced microgrids will enable the user the flexibility to securely manage the reliability and resiliency of the system and connected loads. By shifting resources and partitioning the systems in different configurations, a system-survival resiliency essentially is created. System owners can then optimally use system resources to address threats and potential consequences, and even respond to short-time-frame priority changes that may occur. Whether the primary driver for establishing a microgrid is cost saving, surety, or reliability, benefits will accrue to the system owner.