In 2004, the United States military began a collaboration with NextEnergy to design and manufacture a “mobile micro grid.” This initial product concept evolved over the years into a device now known as an electronic power control and conditioning (EPCC) module.
“It acts like a power hub,” says Max Dorflinger, director of program delivery for NextEnergy. “You can concurrently interconnect up to eight different kinds of electrical power generators or input power sources to it, and it aggregates all of the power inputs while creating a single clean power output.”
Launched in 2002, NextEnergy is a nonprofit organization whose mission is to become one of the nation's leading catalysts for alternative and renewable energy. By bringing promising technologies to maturity in the marketplace, the company seeks to accelerate the impact and profitability of this increasingly important industry. Already managing millions of dollars of research projects, NextEnergy is developing new technologies for power generation, transportation, and fuels.
The EPCC not only accommodates a variety of generator types, but renewable power sources and exported power from hybrid electric and electric vehicles as well. “You can put all kinds of different, incompatible power sources together,” Dorflinger explains. “You can take a 50-hertz (Hz) generator and a 60-Hz generator-plus sources of wind power, solar, fuel cells, and exported vehicle power-and aggregate them to a single output.”
In this manner, military personnel have immediate access to reliable, convenient, mobile power in the field. Plus, because the innovative product saves fuel through managing power sources and loads, it saves money while supporting increasingly prevalent green initiatives.
But perhaps the most critical advantage is the device’s “force protection” benefits. “Not only are there fuel savings, but it reduces the number of times that our forces need to be put in harm’s way,” Dorflinger emphasizes. “When it comes to our soldiers, it saves lives. It helps and protects them, because you don’t need to rely on so many convoys constantly bringing in fuel.”
When NextEnergy first began developing the EPCC, it was working with an inverter company to supply a key component of the product. But contractual and technical difficulties stalled the relationship, prompting NextEnergy to seek a different supplier.
“We were looking at all kinds of inverter manufacturers and came across a generator distributor who was a rep for the Eaton line, Coffman Electrical Equipment,” Dorflinger recalls.
Based on the technical specifications of the EPCC, the rep firm recommended that NextEnergy implement the Eaton 9395 UPS within the module.
“We weren’t initially seeking a UPS,” Dorflinger acknowledges. “But when we were bidding out the project, that was Coffman’s approach. “We did some investigation and found the 9395 to be a very good product that we believed would serve our needs with very little engineering development. And that has proven to be true.”
The 9395 was just making its way off the production line in the fall of 2007 when NextEnergy purchased a pair of 275-kVA units to incorporate within its first EPCC test module. “I think we actually bought serial numbers one and four,” Dorflinger recalls.
The company has since deployed five other 9395s, which are modified to meet the specific requirements of the EPCC product line. “The UPS is our core, main subsystem for the module,” Dorflinger explains. “The 9395 serves as the main output device. We utilize the input port on it and draw power from the dc storage bus where you typically have batteries.”
Where batteries would reside when used in a standard UPS application, NextEnergy instead connects its input ports-converters that enable compatibility among the different types of generators-and a bank of ultracapacitors, which provide short-term ride-through capabilities when generators are attached.
“Generators typically have to be oversized greatly so they won’t experience large dips in frequency and voltage,” Dorflinger notes. “With the ultra capacitors tied to the direct-current storage bus in the UPS, we take care of the ride-through, and the input power sources don’t see large swings in the load, which increases reliability.”