Navigant Research Blog

In Major Storms, Utilities Turn to Technology

— June 6, 2013

According to Oklahoma Gas & Electric’s System Watch web portal, more than 140,000 of its roughly 800,000 customers lost power during the second of two Oklahoma supercell tornados on May 31.

Everyone wonders what is going on in the cockpit when the plane is stuck on the tarmac.  In the modernized utility distribution control center, the operators have complete and current situational awareness of tens to hundreds of distribution circuits (OG&E has 1,100 circuits in its service territory), and sometimes more than a million meters.  Like a pilot in the cockpit, grid operators will have stackable monitors, color coded visualization on a GIS-enhanced interface, and the capability to quickly zoom in on alarms and provide intel to assessor, restoration crew etc.  Several such smart grid functions will have been used and useful in the overall effort of scouting, repairing, and managing outages in Oklahoma over the last 2 weeks.

On April 27, 2011, the resilience of Alabama Power Co. (APC) was tested in the most severe weather incident in the state’s history.  The outbreak of tornados resulted in 239 deaths.  Roughly half of Alabama Power’s 1.4 million customers were without power after more than 3,000 distribution transformers and twice as many poles were downed.  Eight distribution substations were either damaged or destroyed and 400 transmission structures were broken.  Yet, it took only 7 days for the utility to restore power.

The Next Generation

More than 10,000 mutual assistance resources were utilized, meaning restoration crews came from other states to help.  The company took a decentralized and mobile command approach; it used 11 staging areas, each equipped with a distribution management system (DMS) to manage remote switching and other operational control.  During less severe storms, APC operators can turn on an autopilot function (known as fault location, isolation, and service restoration, or FLISR) in the DMS to speed up service restoration, saving thousands of customers from sustained outages every year.  The smart utility’s goal is to minimize customer impacts by reducing restoration time when major events occur.  Utilities are looking to information technology / operational technology (IT/OT) integration and increased mobility to assist with outages.

In the event of outages, utilities rely on operational systems to notify customers of causes and estimated restoration times.  Next-generation DMS will be integrated with outage management to provide additional inputs for visualization and decision support to better address impacted areas.

Advanced workforce management (WFM) solutions that enable utilities to forecast, schedule, dispatch, and monitor progress of outage crew have gained increased interest.  WFM is carried out with the assistance of outage management tools that analyze outage reports to determine the scope of outages and the likely location of problems.  An outage management system (OMS) or a DMS compiles information on the times and locations of customer calls, smart meter outage notifications, and fault data from substations and monitoring devices on feeder lines.

Some utilities are reporting that the integration of advanced metering infrastructure (AMI) has given them the capability to reduce outage time by being able to confirm if meters have power or not.  AMI plays out in two different stages of restoration:

  • After performing restoration work in a given area, service at all the meters can be confirmed quickly and remotely before crews move onto the next area.
  • Individual complaints are followed up on in the wrap-up phase of a large storm restoration effort.

Traditionally there are always a lot of single customer outages that end up being “OK on arrival”, meaning a technician was dispatched with a ticket to restore power only to find out power has already been restored.  By confirming power has been restored via AMI and backing that up with a phone call to the customers, hundreds of truck rolls are saved in large storm events.


Duke’s Schneider Aims for Grid Resilience

— January 28, 2013

Source: Duke EnergyAccording to The Huffington Post, more than 660,000 people lost power in Connecticut during Tropical Cyclone Sandy.  A spokesperson at Connecticut Light and Power reported that 90% of these outages were caused by falling trees that downed power lines. Others spoke of heavier damage, such as flooded substations as the root cause.

Utility distribution operators and outage crews put in a tremendous effort to repair damages and restore power.  In the aftermath, utilities are doubling down on grid resiliency to be better prepared for next time.  Smart utilities are investing in looped power lines peppered with intelligent devices in an effort to reduce the outage impact of downed power lines and other faults.  By “looped and intelligent,” I mean power systems that have automated redundancy, enabling faster restoration.  System Average Interruption Frequency Index (SAIFI) is the IEEE metric for the number of sustained interruptions per customer over a year.   The distinction between a shorter and a sustained outage varies from state to state but is most often 5 minutes, meaning a sustained outage is greater than 5 minutes.

In a recent interview, Don Schneider, who oversees grid modernization projects at Duke Energy, told me that, “As part of Duke Energy’s overall Grid Modernization program, we are deploying grid automation devices that help improve SAIFI.”

When dual- or multi-sourced lines with grid automation devices are in place, there will be significant reductions in affected customers during storms that cause heavier damage over a small area (for example one faulted substation in looped circuits), or moderate to extensive damage over a large area (for example a half a dozen randomly distributed faulted lines per dozens of substations, i.e., enough transformer capacity to reconfigure sourcing to some or all un-faulted sections).

“Self-healing teams, by means of two-way communication to fault-interrupting and switching devices, can locate a faulted section of line, isolate that section of line, and restore power from another source,” says Schneider.

Self-Healing Helps Many

He also describes how the investment in self-healing is creating returns for Duke customers in Ohio.  “In our currently active Ohio Grid Modernization project we have installed 24 self-healing teams over the past 4 years.   From these self-healing teams we have experienced 20 operations that have resulted in 30,000 customers that have avoided a sustained outage,” says Schneider.

Based on EPRI research, it’s reasonably conservative to assume that an avoided outage is worth $2.50 to residential customers and $250 to small commercial customers. With a typical 90:10 ratio between these two customer classes that comes out to an average value of $25 per outage. Using this conservative assumption, it’s fair to say that self-healing in the currently active deployment has likely created $750,000 in satisfaction value to Duke Ohio customers.

While self-healing systems can do little when power systems are faulted at the majority of sources within a service territory, it’s interesting to look into cases such as in Connecticut, where 90% of outages were reportedly line faults caused by trees.  Assuming most of the substations were still standing, and if all lines were modernized, the utility could quickly restore 20%(severe) to 60% (moderate) of all affected customers. This means that 132,000 to 396,000 customers would have lights back within seconds or minutes, representing a value of $3.3 to $9.9 million for a single storm.

The performance of some reliability programs can be tracked, and improvements in SAIFI indicates that a deployment is successful.  “Prior to the start of our program, our 2008 annual average Ohio SAIFI number was 1.33.  Our 2012 annual average Ohio SAIFI number is expected to be 1.03,” says Schneider.  He points out that the Grid Modernization program consists of other substation device automation and critical line device automation that also contributes to improved SAIFI.


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