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Page 2: Lessons for the rest of us >> . By Elisa Wood
Dependent on the outside world for fossil fuels, places like Nome face not only shortages, but also sky-high energy prices. Some residents of Nome spend 45% of their income on energy. Similarly, Hawaiians pay more than twice as much for electricity as Californians. Islands often address shortages by building more power plants, particularly wind farms, but that can increase costs even more. So a group of researchers from Carnegie Mellon University's Electric Energy Systems Group (EESG) recently tested an alternative approach in the Azores Islands, a way to use existing infrastructure more intelligently before building new capacity. "This is important because it's not all about capacity; it is not all about building generation. It is about what we call in our research, 'just-in-time and just-in-place," said Marija Ilic, a CMU professor and EESG director. Using resources at just the right time and place requires digital automation and communication tools, aka smart grid, to tweak power plants and wires for maximum output and stability. The team experimented with this approach on the islands of Flores and San Miguel, forecasting the system's future performance, and then automatically balancing supply and demand down to the minute to employ the cleanest resources possible. Dance on the wire
Wind power – a headache for grid operators because of its variability – was at the heart of the experiment. The CMU researchers tackled this variability problem initially as other grid operators do. They used weather forecasts to predict how much electricity wind turbines would produce a day ahead, a few hours ahead and even ten minutes ahead and called upon hydropower or demand response to make up for wind power losses. But for all of the advanced forecasting and scheduling, this approach has a glitch; the wind is fickle. In the last few minutes, it might suddenly defy predictions and gust or drop off, throwing off the grid's balance. "Ten minutes ahead you can predict where the wind would be, but in real-time you will have real fluctuations and if you don't balance it, the frequency will be all over the place and voltages will be unstable," Ilic said. To resolve the problem, the researchers developed highly sophisticated computer applications and automation controls to adjust the operation of a flywheel storage device, sending just the right amount of power between the flywheel and grid in those last crucial moments. The flywheel is expensive to operate, so the smart grid application was designed to call upon it only at the very last moments. Less costly ways exist to stabilize frequency and voltage on the wires; flywheels make sense only when disturbances are large and sudden, according to Ilic. "We had to develop very intelligent controls for when these unexpected events happen, models that didn't exist before. This is a major innovation," she said. "We have shown here for the first time what type of control logic you have to have." Page 2: Lessons for the rest of us >>
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