A Partnership of UConn and Eversource

Eversource Energy Center


Integrating Renewable Generation

Renewable generation includes solar, wind, fuel cells and micro turbines. Often referred to as on-site generation, co-generation, or distributed energy, it can lower costs, improve reliability, reduce emissions, and expand energy options for customers. Eversource has just over 1 million kilowatts (kW) of renewable generation interconnected with our facilities today.

With the use of these resources, there are safety considerations for Eversource customers and field employees. One consideration involves a renewable generation source continuing to energize a power line from a customer’s home or business when the power in the area has been interrupted (for example, in a storm situation). This “backfeed” situation creates a potential safety hazard for line workers.

The proliferation of renewable generation may create other new challenges for utility infrastructure and customers, such as voltage and frequency fluctuations. In particular, battery energy storage is expected to help resolve many challenges, including variable weather conditions.

UConn electrical engineers are studying the connection of renewable generation to model and analyze the control of power distribution grids with integrated renewable resources. This research area provides important information for the safe operation and management of energy storage on a modern grid.


  • The sun could be the world’s largest source of electricity by 2050, predicts the International Energy Agency (IEA), with solar photovoltaic (PV) systems generating up to 16 percent of the world’s electricity, ahead of traditional power sources such as nuclear, hydro and fossil fuels.

  • There are now over 22,700 MW of cumulative solar electric capacity operating in the U.S., and about 20,000 MW of solar capacity are anticipated to be online in next two years (source: http://www.seia.org)

  • In 2015, a new solar project was installed every 2 minutes in the U.S.

  • High penetration of PV systems significantly challenges power supply reliability and stability because PV generation is highly intermittent and demands significant support from the utility grid.

  • Eversource Energy Center is developing new methods for effective modeling, analysis and control of power distribution grids with high renewable energy penetration. Our new technologies enable the power grid to regulate power flow and accommodate more PV and distributed sources with enhanced electricity resiliency for stakeholders.


Goals & Project Updates

Unintentional Islanding

The scope of the project is to:

  • Identify the risk associated with the possibility islanding. Islanding occurs when a distributed generator (DG) continues to power a location even though electrical grid power from the electric utility is no longer present.

  • Analyze how distribution system (including distributed generation) frequency and voltage will react when separated from the utility source.

  • Assess the risk of having unintentional islanding longer than a specified time interval.

  • Establish a risk level associated with islanding possibility and/or establish criteria to be used in future studies.


risk assessment

Schematic detailing our proposed objectives for the unintentional islanding and risk assessment.


Rooftop Solar Interconnection

“Grid-Side System Enhancements to Integrate Distributed Energy Resources.”

Power distribution grids have been severely impacted by ubiquitous integration of distributed energy resources (DERs), the majority of which are photovoltaic (PV) units. For example, as of June 2016, there are over 15,000 residential solar PV projects installed in Connecticut, and research shows over 4,600 additional projects are in progress. This number is projected to quadruple within the next four years. Nationwide, a new PV was interconnected to the distribution grids every two minutes in 2015, a speed that will increase due to the drop of PV costs (down to $0.06/kWh in 2020 without incentives, predicted by the United States Department of Energy).

The specific objectives of the project are to:

  • Mitigate negative impact from high penetration of intermittent resources
  • Develop new methods and analytic approaches to enable successful future wide-scale deployment of DERs
  • Improve grid resilience, voltage management, network efficiency and grid stability

Team Members

Junbo Zhao, Team Lead, Assistant Professor of Electrical and Computer Engineering, University of Connecticut.

Malaquias Pena Mendez, Associate Professor of Civil and Environmental Engineering, University of Connecticut.

Thi Ha Nguyen, Assistant Research Professor of Electrical and Computer Engineering, University of Connecticut.

David Wanik, Assistant Professor in-Residence, Operations and Information Management, University of Connecticut.

Zongjie Wang, Assistant Professor of Electrical and Computer Engineering, University of Connecticut.


Contact Information

For more information, please contact Junbo Zhao (junbo@uconn.edu).

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