Centralized versus decentralized FLISR – what’s right for your network?

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Fault location, isolation, and service restoration (FLISR) is a software application that reroutes powers in the event of a fault to restore power to as many customers as possible, as quickly as possible. Service restoration times range from sub-second to seconds depending on the type of FLISR solution used.

There are two main categories of FLISR – decentralized and centralized:

Decentralized FLISR

Survalent’s Centralized FLISR

Decentralized – A scripted solution that executes pre-defined, programmed activities to re-energize feeders using power from adjacent feeders
Requires script creation for every possible network configuration
Difficult to scale to large grids because the number of restoration scenarios increases exponentially with each additional device
Best suited for feeders with critical loads that require sub-second restoration, such as hospitals
May prove to be laborious to maintain long term

Centralized – A model-based solution that uses real-time data from the network to identify the best network reconfiguration, isolate the faulted area, and restore power to customers outside the faulted area
No need to define a “normal” state. FLISR will base its analysis on the current state of the network eliminating the need to write a script for each possible state
Before transferring load to an adjacent feeder, the solution analyzes that the feeder has sufficient capacity to avoid overloading it
Vastly scalable, so ideal for any size of network, small to large

Due to the expense and complexity of maintaining scripts for every possible scenario, centralized (model-based) FLISR is typically the ideal solution when you want to set up FLISR on more than 10 devices in your network. By being able to adapt to any network configuration, centralized solutions like SurvalentONE FLISR can help avoid the widespread, sustained outages that cause customer outrage, make newspaper headlines, and result in high profile public inquiries.

That doesn’t mean you have to choose one or the other. Advanced model-based solutions like SurvalentONE FLISR let you have the best of both worlds. You can set up decentralized FLISR in areas where restoration times are critical and, for the rest of your network, take advantage of the scalability of a centralized solution to turn a sustained outage into a momentary outage for customers outside the faulted area. Learn more about FLISR and its benefits in Can a 2-hour outage last just 20 seconds? You bet it can.

Frequently Asked Questions (FAQs)

What are the two main categories of FLISR?

Decentralized FLISR: Script-based automation executing predefined restoration scenarios per feeder configuration.
Centralized FLISR: Model-driven automation using real-time network data to analyze, isolate the faulted area, and restore power dynamically.

What are the advantages and limitations of decentralized FLISR?

Advantages: Enables subsecond restoration for critical feeders, such as hospital circuits.
Limitations: Requires scripting for every possible network configuration—hard to scale and labor-intensive to maintain long term as network complexity grows.

How does centralized (model-based) FLISR differ and scale better?

Centralized FLISR uses a real-time model of the current network, eliminating the need for scripting. It analyzes adjacent feeder capacities before transferring load, adapts to any configuration, and scales effectively across small or large networks.

When is one FLISR model preferred over the other?

Decentralized FLISR is most suitable for feeders with critical loads requiring ultra-fast restoration.
Centralized FLISR is ideal for networks with more than 10 devices, where scalability, adaptability, and reduced scripting burden are priorities.

Can utilities combine both FLISR models?

Yes. Utilities can deploy decentralized FLISR in select critical areas to achieve sub-second recovery, while using centralized FLISR across the broader network to ensure scalable, model-driven automation.