Hurricane Sandy has cut power to six million homes across the northeast of the U.S. on Monday night, breaking trees and ripping power lines. But also insidious was the surging sea that knocked out electricity across New York City and in many seaside towns. Consolidated Edison had preventively shut down the grid in neighborhoods prone to flooding, but the utility still experienced “the largest storm related outage in our history.”
That’s in part because of Sandy’s salty surge. “You can’t just pump the sea water out,” says John McDonald, director of technical strategy and policy development at GE Digital Energy. “Dry salt is an electrical conductor. When it covers insulators, the material that prevents the flow of electricity in transformers, switches, and other equipment, it can make electricity flash over and cause a short circuit. It’s also corrosive.” As a result, utility crews in Manhattan and elsewhere have to first pump out Sandy’s brackish tide, spray the equipment thoroughly with fresh water, and dry it with powerful fans, before they can turn the power back on. The same is true for the city’s submerged subway tunnels.
Water World: The Hugh L. Carey Tunnel, formerly known as the Brooklyn Battery Tunnel, connects Wall Street with Brooklyn. It remains filled with Sandy’s surge.
Cleanup can be tedious work, especially when salt water seeps through air vents inside transformers and other machinery. “When the equipment is all washed and completely dry, only then you can energize it step by step, test the functions and make sure that it still works,” McDonald says. “The crews do it by experience.”
That’s something that McDonald does not lack. He’s is one of GE’s experts on the so called smart grid. He says that during bad storms like Hurricane Sandy, the smart grid, which is a network of smart meters, sensors, and other “intelligent” devices and systems, can quickly detect and isolate the biggest problems so that they do not cascade and cause a blackout. “You restore service to customers on the healthy sections of the system and focus the repair crews on the part of the system that had the disturbance,” McDonald says.
McDonald says that smart meters are an effective tool for scoping out the size of a power outage. “If you have smart meters at homes, you know specifically which customers are without electricity,” he says. A utility can mash the smart meter data with information from a distribution management system, an outage management system, and the geographic information system that includes digitized network maps and facility data. These maps include the geographical coordinates of all the switches, poles, meters and other assets that the utility owns. “The integration of these systems shows you the present state of each asset, whether it’s energized or de-energized, under maintenance or out of service,” McDonald says. “As repair crews work, they know exactly what’s being done, they know exactly how many customers are being affected in each area and whether the problem is a pole that is down, or a transformer that is out of service because of water problems.”
McDonald says that the smart grid also helps utilities “figure out which customers should be restored first, it helps you to prioritize, and verify that customers have had their power restored.”
It also helps power companies and their customers stay in touch, which is key during chaotic storms like Sandy. “With a smart meter in their homes, and with the other intelligent devices and systems, you can let the customer know that we know that there is a problem, that we have a crew on the way or already on site, and that we expect to have power restored in a certain number of hours,” McDonald says. “That’s important.” It may not turn the power on right away, but it brings customers peace of mind.