The self-healing grid: Already here & growing

FLISR

By GE Power Vice President, Global Commercial, Brenna Burns

The beginning of 2019 has started us off with extreme weather arising across the globe, including severe cold in North America, high snowfall levels in the Himalayas and Alps, and record heat, wildfires and rainfall in South America and Australasia.

Electric utilities around the world are facing ever-increasing challenges due to these high-impact weather events. And in the calmer moments that follow, our utility customers continually ask us for better ways to respond to the world’s increasingly wild weather patterns.

Our go-to answer is an ADMS + FLISR. This powerful combination is delivering extraordinary results for our customers globally. This message has really resonated in recent discussions with numerous utilities around the world.

What is FLISR?

Fault Location Isolation and Service Restoration (FLISR) takes an overarching view of the network to restore power when outages occur, via a self-healing approach. The software can integrate with both “smart” and manual switches to monitor and maintain power reliability in the face of small fault outages or massive weather events.

FLISR uses telemetry data and situation awareness algorithms to verify and locate faults. It also considers any operational restrictions (i.e., existing faults, active maintenance work, etc) before recommending or automatically executing a sequence of switching actions to isolate the fault and restore power to as much of the impacted network as possible. FLISR can also leverage power analysis data, if available, to select the best donor circuit(s) by evaluating possible voltage violations associated with each restoration action.

When this advanced technology is leveraged on top of a modular Advanced Distribution Management Systems (ADMS), FLISR can improve productivity and efficiency and simplify operational workflow, using real-time network information that spans EHV to LV.

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Yet, utilities employing FLISR in conjunction with manual switches can still benefit as the software’s data intelligence is derived from the as-operated model of the network. This also means FLISR can adapt to abnormal switching (say construction around a feeder) and continue to monitor and present the best switching plans for addressing outages.

At the same time, with the computational power of the ADMS + FLISR, the utility operator gains the ability to run simulations, predict events, proactively train, and ultimately do more to squeeze an outage so that fewer customers are disrupted.

FLISR in action

Several distribution utilities worldwide are leveraging FLISR today. One company, currently controlling about 8000 megawatts of regulated electricity, first tested FLISR on a small group of its feeders in an advisory mode. FLISR was able to sense network faults and propose optimal switching plans, which would then be approved by human operators. When that pilot proved successful, the utility moved forward in just six months to roll out FLISR in all 1000+ of its feeders.

Now, FLISR can run in a self-healing capacity to:

  • Verify and identify faults
  • Analyse best placed donor circuit to contribute to restoration (leveraging power analysis data if available)
  • Propose optimal reconfiguration switching plans
  • Issue controls to restore or reduce outage scope

Human operators do monitor what FLISR is doing, but the software at this point uses telemetry and operator input to intelligently and dynamically optimise the power distribution.

The Advantage of ADMS + FLISR

The streamlining of processes from a fully automated, self-healing network is obvious. Outage times can be reduced dramatically, and the numbers of customers impacted can also be cut down.

But the vast majority of FLISRs in use today are field-distributed, hardware-centric versions. These cost much more per end-point customer being served, and the expense is linear. In other words, both the initial purchase and operation and maintenance costs do not decrease as the system grows.

The benefits of FLISR running within the ADMS is that it provides the utilities with a dynamic, model-based software solution without the need for expensive field-based solutions. The ability to add, remove and alter schemes from within the operational control center ultimately reduces the operation technology (OT) costs.

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For one distribution operator running FLISR in production with closed loop operation, FLISR was able to restore 9488 customers in less than two minutes during a thunderstorm. The following week it restored 5308 customers in less than 90 seconds. In a single year this utility had 32 successful FLISR events with a three-minute average restoration time, with approximately 20,000 customers restored automatically.

At the same time, FLISR’s data insights help better target the efforts of crews reconstructing switches or addressing faults in the field. Further, when FLISR is running on the network and providing intelligence to the switches (directly to automated switches or smart sensors) or funneling the relevant information to the crews handling manual switches, the computational and engineering power needed to determine the best plan of action in an outage is minimised.

FLISR is quick and efficient at figuring out what is happening and what should happen, and adapting as the environment and inputs change. With FLISR isolating faults, making decisions, and doing it that much faster, utilities are finally getting the tools they need to get back up and running fast in the face of unprecedented weather volatility.