More Information, Faster Restoration
At its peak, on Monday, Oct. 29, Hurricane Sandy cut power to more than 36,000 Pepco customers, 26,000 of whom were in Maryland. In all, more than 81,000 of its Maryland customers experienced outages at one time or another during the storm. But the utility's hybrid DA system, which encompasses a Silver Spring Networks wireless field area network, operating in the unlicensed 902-MHz to 928-MHz spectrum with backhaul over a public or private wireless system, proved up to the task.
There were a total of 42 distribution circuit lockouts, 12 subtransmission line lockouts and 450 downed wire events in Maryland, of which 264 were Pepco wires. The rest were either telecommunications or cable wires, or locations where no downed wire was found, according to Pepco's major storm report. Still, the utility was able to restore service to 95% of its Maryland customers in less than a day, with power restored to all those experiencing outages within 50 hours.
Fortunately, Pepco had updated its outage management system (OMS) software just 10 days before Sandy struck. First, the update made it easier for dispatchers to ping meters in the mesh network directly from within the OMS. Second, because the updated OMS displays power-up messages from those same meters, the utility also was able to use the application to identify nested outages.
Overall, in Pepco's Maryland service territory, 380 events were removed from the queue by pinging AMI meters. Across the Pepco system, a total of 1,092 events were removed from the restoration queue that way, materially reducing the number of truck rolls and helping to ensure crews were dispatched to real outages. Score another one for smart grid communications.
Baltimore Gas & Electric (BGE) had a similar experience with Sandy, even though its AMI and OMS systems were not fully integrated. “We started deploying smart meters around April 2012,” said Kevin Collins, a BGE engineer. The utility had selected Landis+Gyr and GE meters, and a Silver Spring Networks mesh network to collect data from those meters. Backhaul is through a Verizon cellular network.
“Around the time Sandy hit, we had about 130,000 meters installed, about a 10% deployment,” noted Collins. That enabled the utility to implement a manual pinging process in lieu of callbacks toward the end of the storm. “We were able to close out 387 OMS jobs,” said Collins, avoiding additional callbacks and truck rolls. “It made it a lot easier.”
Integrate for Success
Sandy hit PPL Electric Utilities (PPL) hard, but “I think we were the first utility in Pennsylvania to restore power to 100% of its customers,” said PPL Senior Project Manager Mike Godorov. And the reason for that is the way the utility has integrated its smart grid systems — meters, outage management system and geographic information system — to get the greatest benefit.
PPL, which began its AMI implementation in 2004, uses an Aclara power line carrier (PLC) system to bring AMI data back to its substations. From there, an internal interface brings information back to the OMS. “The primary way of getting outage information is from customers on the phone, and we use pings from meters to reinforce that,” Godorov said, noting “there are no last-gasp messages with a PLC system.”
The OMS then determines who is out of service, the extent of the outage and the number of customers affected. “It's helped us significantly in being able to determine where outages are and how far up the line they go,” Godorov added, noting the utility had learned a lot during Hurricane Irene and the October 2011 storm that followed. During those storms, he said, “We had issues with calls, so basically we beefed up our interactive voice-response system and strengthened our call centers, so we're really able to answer calls much quicker and more accurately.”
The system also performed well during Sandy. “The communications systems worked. I'm sure there was spotty coverage at times, but we had enough redundancy in our systems to communicate effectively,” said Godorov. “The whole idea is to be as flexible and redundant as possible.” However, the utility cannot sit on its laurels.
As David Glenwright, PPL Electric Utilities' AMI program manager, relates it, “The Aclara PLC system has served us well over the past decade, but the industry has evolved and developed newer systems with advanced features. We are evaluating various options and will be submitting our final plan to the Pennsylvania PUC in June 2014.”