AC power up time is affected by various factors associated with the geographic location of the consumer due to the location’s probability of severe weather events, fire, earthquake, vulnerability of electrical distribution to fallen trees and various other hazards. The risk of power outage is particularly high if the consumer is at the end of a distribution trunk where any interruption of power along the feeder line will certainly impact the end user. This paper describes a custom resilient power system solution at a residence with a vineyard and light commercial installation at the end of an AC distribution feed in Healdsburg, CA. The site is normally grid connected but can rapidly transition to microgrid supported by PV, battery storage, or both. A natural gas generator is integrated into the system for added support against loss of battery or converter resources. On site loads include typical residential and commercial shop loads, lighting, and several single and three phase motors for HVAC, water well, water irrigation pumps, and a 7.5 HP shop air compressor. Recent microgrid testing has demonstrated five full days of site support using the PV installation to supply day-time prime power as well as recharge the battery as prime power in the dark hours. A grid interactive relay controller provides the means to rapidly connect and disconnect from the utility grid. Transition from grid connection to microgrid occurs within ~0.25 seconds. Transition from microgrid back to the utility source occurs seamlessly.
David Johns– Director of Electrical Engineering, CE+T Energy Solutions