There are multiple challenges that military facilities face in implementing islandable microgrids with one of the most, if not the most, significant being cost. Currently bases consider the capability to island only at the point of common coupling with the utility grid in case of a grid outage, which requires larger more expensive power electronics. Renewable energy goals and a desire for greater on-site power generation and lower dependence on diesel fuel for back-up generators requires installation of photovoltaic (PV) panels, battery energy storage systems (BESSs) or other distributed energy resources (DER). Due to their scale, full-base microgrids require more costly design, review, approval, and permitting costs along with much greater DER and power electronic costs. The technology proposed here will enable a base to implement smaller microgrids that provide resilience for critical and non-critical loads in a staged approach that lowers costs and spreads those costs out over longer periods. The main objectives of this project are to:
Integrated Resilient Node Standardization: The purpose of an IRN is to provide a standardized hardware package for clustering critical buildings and loads, e.g. electric vehicle service equipment (EVSE) and connecting the clustered loads to sources of co-located generation, e.g rooftop PV or diesel generators, or energy storage, e.g. BESSs. The initial IRN at any installation will consist of both a real-time (RT) controller for communicating set-points and retrieving data from DERs and loads connected to the IRN and a DER-CAM.OS supervisory controller. Any other IRNs installed at the same facility will be controlled by the supervisory controller instance in the first IRN and will only need their own RT controller instances. The coordinated operation of several node microgrids will often require power exchange between the nodes and reactive power compensation to maintain voltage at each node. DER-CAM.OS: Existing microgrid control systems are proprietary systems from different manufacturers, neither modular nor scalable, do not support diverse DERs, and are not able to interact directly with utility systems, or building energy management control systems. Additionally, these systems are closed, and lack optimization flexibility to support diverse site objectives and incentives. Our innovative control system—the DER-CAM.OS microgrid controller—uses a multi-layered distributed architecture following Institute of Electrical and Electronics Engineers (IEEE) 1547.4 standards, in which control tasks are distributed across hierarchical layers. This type of architecture makes the system modular and scalable (e.g., additional DER and loads can be easily integrated without replacing the entire system).
The benefit of this technology is primarily in the cost savings it would provide Department of Defense (DoD). Spreading out the cost of microgrid installation at a base over five to ten years would reap the advantage of falling prices for PV and BESSs resulting in lower overall costs for the same function. A back of the envelope calculation assuming 10% annual decrease in PV and BESS costs and a 10% increase in engineering and project management, results in about 15% cost savings with a phased IRN approach versus an all up front approach. Addressing critical loads first means that resilience requirements can be met before the five to ten-year completion window. With their standardized modular design, IRNs will also provide a cost savings in upgrading electric infrastructure equipment at bases with or without DERs. Funding approximately one-fifth every other year or so in this approach will likely be easier financially for bases rather than covering the full, 15% higher total cost in a single year.