Public Content Library

Summary

Over the years, University of Virginia (UVA), the University of Virginia Health System, have experienced temporary power outages caused by a multitude of reasons. These outages trigger the resetting of vital equipment which serves a “mission critical” function, and is extremely sensitive to electrical reliability issues. Even minor outages require additional work from the University of Virginia operations and maintenance staff to reset equipment, pose operational and life/safety issues for the hospital, and present safety and reliability concerns for the general University population. UVA’s campus (Grounds) provides more than an academic environment to a large number of people. In addition to the 21,095 students, there are 2,171 full-time instructional/research faculty and 9,919 additional full-time staff employed by the University. The University of Virginia Health System includes, but is not limited to, a Level 1 Trauma Center, a Clinical Cancer Center, and a Children’s Center. According to Dominion Energy – the local power provider, the majority of past power outages can be attributed to physical impacts to the overhead power lines such as primarily are result of severe weather, trees, traffic accidents, and animals. In an effort to minimize and/or eliminate disruption to the facilities, the University took on a project to replace these overhead lines with underground power lines in concrete encased duct banks. The new underground system will be more resilient and less susceptible to outages, creating consistent schedules for operations and maintenance staff. The design included a detailed horizontal and vertical alignment for the entire 3 mile route length and design of 33 large underground vaults spaced approximately every 500 feet. The ductbank connected Dominion substation with two UVA substations located within the Grounds. The construction phase of the project kicked off during the summer of 2016. Construction was complete September 2017. This innovative partnership (fixed asset agreement) required that UVA finance, design, and construct the underground ductbank. Dominion Energy purchased, installed, owns, and operates the electric cables through a master license agreement. The new underground service includes dedicated circuits from Dominion Energy that will only serve the University. Since December 2017, when the ductbank went in to operation, the new underground ductbank has reduced power interruptions by 90%. The University now possesses a more robust and resilient power distribution network. The increased reliability has allowed the University to better support its mission as a state emergency shelter in the event of a natural disaster. Routine momentary outage will now be a thing of the past as they move forward with their underground distribution power system. The day the new service went into operation, several sensitive electronic equipment especially UPSs within the health system did not respond favorably to the incoming power. The UPSs are critical to support patient monitoring equipment. Upon investigation, the total harmonic distortion (THD) was found to be beyond the tolerance limit of the units. It appeared that the units are setup to accept incoming power with 8% or less THD which is the recommended limit set by IEEE 519 for systems less than 1000V. Closely working with Dominion Energy, UVA brought the THD below the recommended levels at the incoming 35kV. Resonance within the distribution system when all the loads were brought on to one transformer appeared to have pushed the THD beyond 8%. This incident has shifted UVA focus from power reliability to power quality. UVA and Dominion Energy continue to work together to optimally size the capacitor bank and “tune” the system. UVA power and light team constantly gets called into help with power quality issues across Grounds. The team helps researchers with critical experiment setups where highly reliable grounding is needed. The team resolves issues with nuisance ground fault relay trips, voltage sag/surge, THD, surge protection, AFCI protection and other issues within buildings that a utility company would not own to resolve. The team provides “root cause” analysis support for incidents that cause either equipment failure, near miss arc-flash, damage to property or injuries to employees. A campus utility (power distribution) team must have competent electrical engineering professionals with “expert knowledge” on power quality elements to be able to resolve these issues.

Session 3B: Electric Distribution Reliability and Resiliency

Speakers

Sathish Anabathula, University of Virginia Facilities Management
William Evans, University of Virginia Facilities Management