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Summary

Various "MUSH" (military, universities, schools, hospitals) institutions have good reasons for increasing their resiliency. Different locations face a variety of factors for consideration, all of which must be considered and calculated before committing to a resiliency project. The Joint Base San Antonio engaged a team of engineers to assist with assessing, modeling and analyzing whether it was feasible to install a microgrid power generation and distribution system that includes solar panels, battery storage and automatic distributed switching. This presentation will center on how a study is typically performed, how it accounts for variables, including distribution and generation assets and whether it applies universally. The study initiated with a discussion about how to frame the study, and how it would address sustainability, resiliency and mission preparedness. It was followed by a recording and review of all base power assets.A six-person team split into three groups, each with an electrical engineer and electrical contractor. The groups walked the base and confirmed measurements and made notes of all assets, including identifying potential issues for the microgrid design. They opened and inspected equipment such as switchgear. They created databases for any unaccounted-for assets and updated previous lists.The next step was to use the data to build a power coordination model using the ETAP (electrical power system analysis) software tool. Engineers created a model based on the inventory assessment, entering photovoltaic power, gas turbine generators, batteries and a microgrid controller into the scenario. They performed a short circuit analysis for rated equipment, predicted load flow for overloaded circuits and did a systems harmonics transient analysis study, which shows how the grid would respond when going from utility to islanding mode. The model tested for distributed generation plug-ins, such as a 15 MW solar array, battery storage and a microturbine combined heat and power generator. It tested how they would work during resilience actions when backup power was needed, including how switching and controls would perform.Based on the models, consultants recommended that the microgrid model was viable. They identified resilience actions, such as a generation installation; and new switching and controls that would allow the base to provide back-up power to critical loads.

Session: Microgrid Workshop

Speakers

Ernie Leaf, Stanley Consultants