Design, Modeling, and Control of Hybrid ESS for DoD Microgrids
Nathan Johnson | AZ Board of Regents on behalf of Arizona State University
This project demonstrates a storage-enabled microgrid that enhances installation energy security with greater autonomy during a grid outage and reduces operating costs during grid-connected operation. Delivering resilience with a return on investment, the work offers a cost-effective way to achieve broad Department of Defense (DoD) and branch-specific objectives for 7-14 day mission autonomy while also providing a variety of business models and controls approaches to improve financial return and adapt to specific installation needs. The approach evaluated single energy storage asset and hybrid energy storage systems that integrate multiple storage technologies to value-stack benefits in site-customized DoD microgrids.
Primary components of the system include short-duration storage (Skeleton Technology ultracapacitors) that are integrated with medium-term storage (Blue Planet Energy Lithium Ferrous Phosphate) to value-stack the benefits in site-customized DoD microgrids. One or more legacy generators are integrated into the system and any existing solar photovoltaic is also integrated. The controller developed by Arizona State University and Ageto provides main capabilities for (a) operating in parallel with the grid to achieve economic savings, (b) operating during grid outage to increase mission survivability and mission autonomy, and (c) reliably and stably transitioning between grid-connected to islanded mode, and back. The controls approach provides flexibility for behind-the-meter and in-front-of-the-meter applications, and can be easily configured for operation with different combinations and sizes of assets. XENDEE capability provides cost-optimal sizing and dispatch logic with consideration of feeder topology and power flow, thereby informing engineers where to place assets for greatest performance goals and any associated distribution network upgrades. 350Solutions planning and verification processes deliver results that meet expectations and include a comparison of quantitative performance metrics from power-hardware-in-the-loop testing and controller-hardware-in-theloop testing with scaled up systems in field testing.
Project benefits for the Environmental Security Technology Certification Program (ESTCP) site locations have general applicability to DoD installations using empirical testing that demonstrates how the solution can be adapted to other sites.
- Increased resilience – Surpass minimum seven-day autonomy requirements during grid outage.
- Improved economics – Reduce energy and operation and maintenance costs as directed by ESTCP and DoD Energy Policy, and further, to permit revenue generation through access to ancillary services markets.
- Increased battery life – Demonstrate ultracapacitors paired with battery storage to improve lifetime of batteries, and therein improve project economics.
- Greater decision making – Controls enhancement allows an operator to make real-time mission changes and load prioritization decisions to maintain/improve survivability during outage.
- Increased flexibility – Adapt to many installation locations and legacy assets using a technology agnostic approach that includes interoperability with over 60 types of assets and controls that are abstracted to be applied in behind-the-meter and in-front-of-the-meter markets. Further, the solution can more generally address DoD goals for adaptive basing as outlined in the National Defense Strategy.
- Technology agnostic – Interoperability with legacy assets and new assets, with vendor registers mapped to high-level control strategy. Mitigate risk to vendor cost and technology changes.
- Mitigate risk to fuel shortage – Demonstrate that solar + storage improves survivability of a diesel-only microgrid, even when fewer generators are available.