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Eversource Energy Center



Author: Hurricane Sally Inundation Map

Author: Vulnerable Trees, High Winds, Other Factors Combined for Unusually Severe Storm Damage from Isaias

Aug. 14, 2020

STORRS, Conn. – Gypsy moth infestations and drought conditions in recent years have weakened trees throughout Connecticut to such an extent that forests were particularly vulnerable when the remnants of Hurricane Isaias swept through on Aug. 4, causing extensive power outages related to tree damage.

Those factors, along with the capricious storm’s unusual timing and localized pockets of extreme winds, made it more difficult than expected to predict the extent of possible electrical outages and create accurate restoration plans, according to a new analysis by the UConn-based Eversource Energy Center.

The center, based in UConn’s Innovation Partnership Building, is a research lab that develops storm damage modeling technology and forecasting to help Eversource – New England’s largest energy delivery company – plan for reliable service throughout Connecticut and New England.

Hurricane Isaias had weakened to a tropical storm by the time it reached Connecticut, but was unique in several ways that converged to contribute to the power outages that lasted for several days, according to the EEC’s analysis.

The EEC issued five predictions to Eversource between Aug. 1 and Aug. 4 for the utility company’s territory, and also shared four with United Illuminating, the state’s other large electric supplier. In almost every case, each report predicted significantly increasing storm severity, with the last predictions – released on the morning of Aug. 4, a few hours before the storm – indicating an extreme impact, in the range of 3,000 to 6,000 damage locations for Eversource service territory and 400 to 800 for United Illuminating.

Even given those increasingly ominous indicators, the storm’s damage exceeded the Outage Prediction Model (OPM) as strong winds blew through the state and non-meteorological factors – including the weakened and insect-damaged trees – became an unexpected part of the equation.

An extreme drought affected the region in 2016, and unusually dry conditions persist in much of the state. That had degraded the ability of many trees’ root systems to withstand sustained wind levels of a major weather event, particularly in northern areas of Connecticut. Also, tree canopy defoliations by Gypsy moth infestations in 2016, 2017 and 2018 created vulnerabilities statewide.

The UConn Outage Prediction Model (OPM) is a well-established, state-of-the-art model which uses weather forecasts, land cover, vegetation, and infrastructure characteristics, and historical outage records, to predict the amount of damage in the electric distribution system. Development stages and applications of the model have been published in several top tier peer-reviewed
international journals, demonstrating its accuracy in predicting power outages for a host of weather events, including thunderstorms, hurricanes, nor’easters, and snow and ice storms.

Isaias’ unique characteristics affected the OPM modeling outcome in several ways, most particularly because the storm was disintegrating as it passed over the State of Connecticut, causing higher sustained winds and microbursts in localized circulations across a widespread
area. In these localized pockets, sustained winds reached the level experienced in both Hurricanes Sandy (October 2012) and Irene (late August 2011).

At the same time, data included in the model for similar magnitude storms such as Sandy and Irene reflected significant meteorological differences between those storms and Isaias: Sandy occurred later in the year when leaf area was lower, and Irene involved greater precipitation levels.

In mid-summer, Connecticut’s forests have the highest leaf area for high winds to impact, causing more tree and branch movement than when leaf area is lower. With drought conditions weakening the strength of root systems to an unprecedented extent, the combination of these factors caused an extreme impact.

Moreover, the National Weather Service confirmed that a tornado, characterized by a maximum wind speed of 95 to 105 mph, occurred in Westport, where power outages were extensive. Other small tornadoes and microbursts are suspected to have taken place in some locations, further indicating localized pockets of extreme winds.

“When we issued the first prediction on Aug. 1, the hurricane was still located in the Bahamas and there was a significant uncertainty on the track,” said Emmanouil Anagnostou, EEC’s Director, and a UConn professor in the Department of Civil and Environmental Engineering.

“But at the time of the fifth and final prediction, during the morning of Aug. 4, a few hours before the storm, we were certain that the storm would produce an extreme impact in Connecticut, although not as severe as what was actually predicted due to the novel characteristics of Storm Isaias,” added Diego Cerrai, EEC’s manager and an assistant professor in the Department of Civil and Environmental Engineering.

Going forward, the EEC plans to incorporate more data on vegetation science and drought conditions in its modeling, helping to better predict future warm-season extreme storm impacts.

EEC researchers also say another key observation from tropical storm Isaias and its aftermath is the recognition that vegetation management should be implemented more widely, perhaps including more attention to large trees that have been outside of historical trimming zones. The EEC’s faculty members who specialize in natural resources will be analyzing data from the Center’s Stormwise forest management sites and remote sensing data from NASA to investigate tree damages as it continues reviewing the incident.

This year’s hurricane season is expected to be active, and lessons learned from predictions of tropical storm Isaias will be part of the EEC’s data it uses as it continues monitoring for ways in which future weather events could impact the power grid.

The University of Connecticut Outage Prediction Model (OPM) Post-Storm Report for Tropical Storm Isaias can be viewed here:


Author: EEC’s Cory Merow Interviewed by NY Times and Scientific American

Dr. Cory Merow is an assistant research professor in UConn’s Ecology and Evolutionary Biology Department and researcher for Eversource Energy Center. He was interviewed by both the New York Times and Scientific American for insight into climate change and its ecological impact.

The New York Times article can be read here: https://www.nytimes.com/2020/04/15/climate/wildlife-population-collapse-climate-change.html
The Scientific American Article can be read here: https://www.scientificamerican.com/article/rising-temperatures-may-push-ecosystems-past-their-limits/

For more information on Dr. Cory Merow, his website is https://cmerow.github.io/
For more articles on the ecological impact of climate change, please see this site https://www.altmetric.com/details/79339301/news

Author: EEC Welcomes Dr. Ha Nguyen

Eversource Energy Center is pleased to announce the recent hire of Ha Thi Ngyuen, Ph.D., as an Assistant Research Professor to aid in our power engineering research. Dr. Nguyen will lead the Center’s newly acquired RTDS power grid test bed, and will support research projects related to integration of renewables in the power grid, cybersecurity and power grid resilience. Dr. Nguyen will also develop a training program for utility engineers on the use of the RTDS test bed, and you will contribute to the grid modernization certificate program offered by the Center.

Dr. Nguyen received her Ph.D. from the Center for Electric Power and Energy at the Technical University of Denmark (DTU) in 2018. She has worked with the Center Energy Research at University of California, San Diego and for Electric Power and Energy at DTU. Her research interests are power system modelling, operation and control, geographically distributed real-time co-simulation, hardware-in-the-loop simulation, frequency stability and control, and renewable energy integration.

Author: Robert Fahey Wins 2020 UConn-AAUP Excellence Award

Eversource Energy Center Associate Director Robert Fahey has been named the early career recipient for Excellence in Research & Creativity Award. Each year the University of Connecticut works with AAUP, a faculty-based union, to recognize UConn faculty who have gone above and beyond in teaching.

Congratulations to Professor Robert Fahey on behalf of the EEC!

Author: EEC Colloquium Series: Dr. Ha Nguyen

Dr. Ha Nguyen will be giving a talk titled “Challenges and research opportunities of real-time simulation in modern power systems.”

Real-time simulation application is well recognized as an effective approach for modeling, developing and testing components in power systems with high accuracy, low cost and more flexibility before field deployment. This talk first presents some experience in real-time simulation of large-scale power systems with different power electronic components and hardware-in-the-loop simulation for testing devices. Then, the challenges of real-time simulation in renewable-based grids are analyzed. The talk will conclude with research opportunities for real-time simulation in renewable-based systems, which require more research for modern power systems.

Link for PDF flyer: https://www.eversource.uconn.edu/wp-content/uploads/2020/03/Nguyen-Ha_MAR2020Flyer.pdf

Link for UConn Event: https://events.uconn.edu/event/75896/2020-03-13

Author: EEC 2019 Annual Report Published

Eversource Energy Center’s 2019 Annual Report has been published and can be viewed or downloaded as a PDF here.

The Annual Report contains information on research, publications, and finances of the Eversource Energy Center.

PDF Link: https://www.eversource.uconn.edu/wp-content/uploads/2020/03/EEC-Annual-Report-2019-Web-Version.pdf

Author: EEC Colloquium Series: Dr. Lei Wu on Feb 24th

Associate Professor Lei Wu will be giving a talk on February 24th, 2020 at 1:30 pm in UConn building ITE 336. The talk is titled “Interdependency of Gas and Electricity Infrastructures for Enhancing Energy Efficiency and Security.”

For a PDF version of the flyer, click here.

Author: EEC Colloquium Series: Dr. Hasan Ul Banna on Feb 10th

Author: Announcing New Faculty Positions at EEC

Eversource Energy Center is seeking to hire three new positions. Positions are described and linked below.

  1. Endowed Chair position for Eversource Energy Center and the Electrical and Computer Engineering Department. This is a a tenure-track faculty position at the associate or full professor level. The candidate will be expected to develop and sustain an internationally-recognized and externally-funded research program in power engineering preferably either by targeting multi-PI center opportunities or creating such opportunities. The expected start date is August 2020. A full job announcement with application instructions can be found at https://academicjobsonline.org/ajo/jobs/15020.
  2. Assistant or Associate Professor in AI-based Prediction for Power and Environmental Systems. This is a tenure-track position with the Eversource Energy Center (EEC) and the School of Engineering at the University of Connecticut (UConn). The candidate will be expected to conduct research, education and outreach related to AI-based predictive modeling for power and environmental systems. The expected start date is August 2020. A full job announcement with application instructions can be found at https://academicjobsonline.org/ajo/jobs/15797.
  3. Assistant Research Professor in the Electrical and Computer Engineering Department and Eversource Energy Center. This is a non tenure-track position wherein the successful candidate will be expected to develop research projects based on the RTDS grid simulation system and sustain an internationally-recognized and externally-funded research program in power engineering. This position is for immediate hire. A full job announcement with application instructions can be found at https://academicjobsonline.org/ajo/jobs/15137.

Eversource Energy Center | Innovation Partnership Building: 159 Discovery Drive, Unit 5276, Storrs, CT 06269-5276 | E-Mail: eversourceenergycenter@uconn.edu