Vermont Microgrid Will Showcase DG Versatility

Issue 1 and Volume 108.

Steve Blankinship, Associate Editor

Design is underway on a first-of-its-kind microgrid that will connect a cluster of propane-fueled reciprocating engines, energy storage devices, microturbines, wind turbines and photovoltaic panels to serve business and residential customers. A microgrid power network is defined as two or more distributed generation assets configured in a network and capable of operating either in parallel with, or independent from, a larger electric grid, while providing continuous power to one or more end users.

Waitsfield, Vermont-based Northern Power Systems announced the project late last summer. The microgrid complex and its generating assets will operate in parallel with the bulk utility generation and distribution system to provide dramatically increased power quality and reliability to businesses in the complex, which will include Northern’s new headquarters facility, and nearby residences.

Mad River Park, located in Waitsfield, will be a demonstration project undertaken with the support of the Washington Electric Cooperative (WEC), the Vermont Department of Public Service (DPS), and the U.S. Department of Energy (DOE).

The system will include next-generation power network architecture utilizing proprietary technology incorporating combined heat and power (CHP) and mixing fossil-fueled engines with advanced generation assets such as wind and solar technology. Northern’s MicroGrid technology incorporates power conversion capability, static isolation switching systems coupled with advanced power network modeling software tools and control techniques. Product commercialization of these technologies is underway and Northern will formally roll out a number of the new products for use in both microgrid systems and in general DG applications.

This aerial view of the Mad River Business Park shows Northern Power Systems’ new facility near completion. Photo courtesy of Northern Power Systems.
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“This first-of-a-kind project will highlight, in a real-world setting, the vast potential for networked distributed generation to cut energy costs and accelerate the use of clean renewable energy,” says Dan Reicher, executive vice president of Northern Energy Power Systems and a former U.S. assistant secretary of energy. “In a larger sense, the microgrid concept represents a tangible distributed generation solution to the serious effects of widespread power outages and recurring reliability problems in the U.S. electric grid.”

In addition to providing power to WEC’s Mad River Park customers, the power network will achieve several important larger objectives, according to Reicher. “It will create economic models for evaluating the feasibility and merits of such projects at specifications and advance the technical and institutional know-how necessary for the development and deployment of additional utility or customer-initiated microgrid networks in the U.S.”

With its particular focus on emerging and renewable technologies, the project is expected to dramatically underscore why networked systems facilitate the use of distributed, sustainable energy. Developers also expect the Mad River microgrid to provide a blueprint on how these multiple DG technologies, working together, can deliver higher generating efficiencies and reduce overall environmental impact.

Using propane-fueled reciprocating engines and microturbines, a photovoltaic solar array and a small wind turbine for an initial output totaling about 350 kW, the system can be programmed to operate in several distinct modes, including total isolation from WEC’s system during voltage sags, spikes, or transients that cause power to deviate from utility or customer-defined parameters. Power from the local WEC substation will be monitored via an advanced protective relay, which will detect scheduled or unscheduled power events and enable the system to “island” the park from WEC’s distribution system during such occurrences, providing a seamless, uninterrupted delivery of power. The system can also be programmed to operate in a grid-following mode.

All generation assets will be tied into WEC’s distribution system. Emerging technologies such as fuel cells, Stirling engines and flywheels may eventually be incorporated into the network.

“For utilities, microgrid networks may offer a cost effective alternative for upgrading aging or insufficient distribution systems and to expand infrastructure beyond existing lines to meet growing demand,” says Reicher. “By offsetting grid power with network power, utilities can better predict daily levels of energy output, while also expanding their customer base, especially during peak hours.”

He also believes utilities will be able to dispatch microgrid generation in order to smooth bulk system demand, avoid price spikes and potentially achieve conservation voltage regulation goals. Such networks could also let utilities take advantage of spot sale opportunities, marketing such systems directly to ideal customers such as business parks, colleges and universities and hospital networks.

Northern will be commissioning the Mad River Park power network in several phases in coming months and expects full operation this year.