Pushing the Envelope

Authors: Aleksi Paaso, Shay Bahramirad and Dimitra Apostolopoulou, ComEd, USA

Enabled by technological advancements and motivated by the growing need to increase security, resiliency, efficiency, flexibility, and adaptability, microgrids have been proposed as a solution for supplying electric power in an increasing array of applications in the modern distribution systems. (Figure 1.)

Commonwealth Edison (ComEd) – a unit of Exelon Corp. (Chicago, Illinois, U.S.) that provides service to approximately 3.8 million customers across northern Illinois – is pushing the envelope on improving the distribution grid resiliency by deployment of microgrids. As part of the recent legislation proposal to the Illinois General Assembly, ComEd proposed a microgrid pilot program to allow an investment of $250M to deploy six microgrids to various geographic locations throughout the ComEd service territory. The proposed pilot program is unique on its scale and due to the fact that it is initiated by a utility.  (Figure 2.)

 Current Microgrid Landscape in the US
Microgrids are surfacing throughout the United States; their installed capacity is expected to double by 2020. The first microgrids were installed to specific applications, including remote communities, college campuses, and military bases; however more recently, installations geared towards a wider range of applications have begun to emerge. Following the Super Storm Sandy, several states in the east coast have established funding mechanisms for microgrid projects.

Many of these state incentives are driven by the need to support a critical infrastructure and emergency preparedness through resiliency improvements in the electric power grid. Such programs and mechanisms include but are not limited to the Connecticut Microgrid Program, the Maryland Resiliency through Microgrids Task Force, the New Jersey Energy Resiliency Bank, and the New York Prize competition. In the aftermath of Super Storm Sandy, the emphasis on the east coast has been grid resiliency, as the states have become more aware of the incremental value of resiliency that microgrids can provide. Meanwhile on the west coast, the California Energy Commission is pushing for reduced emissions through low-carbon microgrids for critical facilities.

While grid resiliency is the key focus area on the east coast, the integration of renewables and consequent reductions in carbon emissions are important drivers in California.
Currently, the efforts around microgrids in many states are being driven by state officials to protect public good infrastructure during catastrophic events such as natural disasters, cyber and physical attacks.

Benefits in Microgrids
The utilization of microgrids in utility distribution systems encompasses a variety of technical, societal, economic, and environmental benefits. Application of distributed energy resources (DERs) can reduce the need for upgrades to distribution and transmission facilities. 
The placement of DERs within the proximity of the load with capability to island from the main grid supports the local reliability, security and resiliency.

Moreover, microgrids can provide system support in times of stress by aiding the grid restoration after faults.
The utility resources can be directed elsewhere, while the microgrids keep their areas in operation.

Improvements in restorations are particularly important due to the increasing severity and frequency of extreme weather events as well as the threat of physical and cyber-attacks to the grid infrastructure.  While the enhanced resiliency and reliability are driving a number of microgrid deployments, microgrids support the economic grid operations. They reduce the overall losses on transmission and distribution systems. In addition, microgrid systems can provide ancillary services to the grid. Renewable DERs, integrated in a microgrid, also support the reduction of CO2 and other harmful emissions.
The full value of microgrids is a resultant combination of multiple benefit streams in grid operations, economics, and sustainability.

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