Significant fuel savings and operational efficiencies are some of the benefits of an intelligent power management system that includes multiple energy sources.
The U.S. Army has tested a proof of concept for a smart electrical grid that would support tactical operations in the field. The concept, which was tested last summer, could save potentially billions of dollars in fuel use at remote forward positions. By eliminating the need to transport fuel for generators at such encampments, the new Tactical Operations Smart Grid also carries with it the potential of saving the lives of warfighters.
The smart grid, which takes advantage of multiple off-the-shelf electrical energy technologies, is being developed and tested by the Army’s Research, Development and Engineering Command’s (RDECOM) Communications-Electronics Research Development and Engineering Center (CERDEC). Along with helping set specifications for a future vendor-developed system, data from the tests also are being compiled as part of the Defense Department’s longer-term program of reducing both manpower and fuel use for energy generation.
“These systems are designed to integrate existing military-standard tactical generators managed by portable electric power systems out in the field, providing the ability to intelligently work within a grid operation,” says Michael Zalewski, a project mechanical engineer with CERDEC’s Command, Power and Integration (CPI) directorate. The tactical microgrid is being developed as part of the HI Power program, for Hybrid Intelligent Power. Newly developed digital controllers allow the system to balance electrical production, storage and demand dynamically, he explains, “and by doing this, we’re able to right-size the production of power to the load and demand at that point in time.”
The smart grid systems under development are scalable, says Zalewski. Smaller systems are capable of supporting brigade and battalion field operations with as much as 100 kilowatts maximum of power, and larger systems are capable of managing and producing as much as 1 megawatt of electricity for bigger installations. The CPI also is exploring other smaller-configuration mobile generating systems that can be integrated into the smart grid system; are mountable on a small trailer; are able to be towed by a humvee; and are capable of generating as much as 5 kilowatts of energy.
The tactical smart grid is designed eventually to replace the standard configuration of stand-alone electrical generators combined with power procured from local community power grids and managed through equipment generally known as the power distribution illumination systems electrical. “It’s a ruggedized version of breaker panels that you have in your house. It allows the warfighter to provide both single-phase and three-phase distribution that is current-over-limited protected,” explains Zalewski. One of the limitations of such a system is that it allows warfighters only one power source (a generator or a solar panel) at a time. By comparison, the tactical smart grid “will allow soldiers to distribute more readily from multiple sources and also to right-size these systems, so you’re not asking a large generator to provide power to a small single load or vice-versa, a single generator that is being overloaded at peak,” he explains.
“Part of the problem with the existing system is that we have generator sets that are overtaxed, and they have way too much load, or generators that are undertaxed,” says Darren Stephens, a CPI electrical engineer who also is working on the tactical smart grid project.
At the heart of the tactical smart grid system is a computer-based controller that makes moment-by-moment decisions on how much power is required by the equipment Army warfighters take into the field during tactical operations and matches it with the power generating capability from the sources at hand. “It intelligently matches input to output, without the user having to make a decision or to interfere. It will also intelligently determine what these sources are,” explains Stephens. The tactical smart grid development team is writing algorithms designed to govern how the controller selects between generators, solar collectors, wind turbines, batteries and power obtained from the local community grid when available. An additional goal, he says, is to reduce fuel consumption significantly.
Because the smart grid is able to adapt to a range of electrical loads and tap into multiple sources of electricity, CPI developers report they have begun to see tangible fuel savings of between 15 to 30 percent during the testing process compared with existing power management systems. In addition, developers also have found that the smart grid reduces the amount of operating time for diesel-fueled generators, yielding additional savings in terms of extended periods of time between required maintenance.
The tactical smart grid can provide information that helps anticipate future operational problems. For example, the smart grid controller can inform an operator if one of the diesel generators is about to run out of fuel, something not possible with current systems. The controller also is able to warn an operator if one of the generators is about to experience mechanical trouble, so the operator can switch to an alternate source of power while repairs are being made. Generators can be connected in tandem through a smart grid controller, allowing one generator to remain in operation to support power needs while normal maintenance is performed on the other generator. By comparison, an existing, standard-issue power system supported by only one generator often must be taken offline periodically for routine maintenance, requiring a tactical operations center to make other power arrangements during the maintenance blackout period.
The smart grid system is being developed with electrical storage in mind, offering an additional alternative in the event that a primary generating source is offline for maintenance or repair. Lithium-ion or lithium-iron-phosphate batteries are being tested, says Zalewski, along with a number of novel energy technologies, including compressed air storage. “One of the things we’re looking at is enabling the operation of these discreet technologies on the grid, not developing the technologies themselves but developing the standards and the interface protocols and providing a common network of sorts, which will allow all these items to work together,” he declared.
Another element of the scalable smart grid system being developed by the CPI team is called the Renewable Energy for Distributed Undersupplied Command Environments (REDUCE). “If you have solar panels available, for example, and it’s the middle of the day, it might be best to pull from the storage system and use the solar to recharge the batteries, rather than turning on the generators,” explains Stephens. At night, however, the controller might determine that it is best to turn on a generator to meet power needs or use the generators to recharge batteries during the periods of lightest demand, when soldiers are asleep. “We’re looking at the logic behind making the renewable energy and the generators all work together to provide the soldier with an uninterruptible power supply while reducing fuel consumption,” he concludes. Additional smart grid development now underway will give researchers more insight into efficiencies gained from various combinations of energy sources, again depending on warfighter needs at different times.
Development of the tactical operations smart grid has been influenced heavily by the needs of warfighters at the front lines. Stephens says that one group on the CPI team has been devoted to surveying soldiers in the field on their power needs and talking to other organizations within the Army that also have power management requirements in battlefield environments. In addition, a proof-of-concept smart grid test that took place last summer at Fort Dix, New Jersey, yielded valuable information that is directing and informing subsequent ongoing system development. “Power should be available when the warfighter needs it,” says Stephens, summarizing the feedback he received from helping to run the Fort Dix tests.
The CERDEC team developing the Tactical Smart Grid is continuing its development work based on the findings of last year’s successful proof-of-concept demonstration and ongoing testing. The eventual goal of the CERDEC CPI tactical smart grid development program is to write the specifications and operational algorithms for a system that would be designed and built for the Army by future contractors. “We should be able to give these standards to any contractor, and they should be able to come up with systems that are fully compatible with one another,” Stephens explains. In addition, the smart grid concept is being developed as an open architecture system, which will allow multiple vendors to provide interoperable components for the tactical smart grid, avoiding the problems that ensue when one contractor provides a turnkey, sole-source system.