Distribution Automation – The Key to Achieving Top-Quartile Smart Grid Reliability

The electric utility industry has envisioned distribution automation in one form or another since the early 1980s. With recent improvements to communications technology (particularly cellular telephone/data, GPS satellites, power line carrier, and fiber optic cable technologies) that vision is rapidly becoming a reality, and, in fact, a virtual necessity, as customers have come to expect application of modern digital technology in all aspects of their lives.

Distribution Automation

Generally, electric utilities have adopted one of the following approaches with varying degrees of success:

• Limited pilots applying available technology
• Limited installations of new technologies on worst-performing circuits of a localized form of distribution automation (e.g. mid-point recloser, tie-point, either without intercommunication-by relays and automatic switching schemes only-or with ‘team’-based communication among a group of devices)
• Area-wide distribution automation, with full communication to and from all devices, and a sufficient number of switches and ties to divide feeders into smaller zones, thereby enabling rapid and automatic isolation of faults to minimize service restoration time and the duration of customer outages.

Top Quartile Smart Grid Reliability

There are three examples of utilities (within 100 miles of New York City) that implemented this type of solution:

• Long Island Lighting Company-LIPA
• Public Service Electric and Gas
• Consolidated Edison’s Overhead Distribution System in Westchester County).
  

  Electric System Reliability (SAIDI)

Each electric utility has consistently achieved industry-leading SAIDI performance of less than 60 minutes per year (storm-adjusted), a standard that could not have been met without distribution automation. Recognizing that first quartile SAIDI performance is generally in the range of 80 minutes and industry average is 120 minutes, one can see the obvious advantage of these types of investments.