What utilities can do now to prepare for a major storm event—4 key initiatives

December 14, 2017 Chad Renshaw

In hurricane-prone Florida, preparing power delivery systems for resiliency in advance of storms can reduce restoration time and costs

 

As a Floridian, I can tell you we are all too familiar with the devastating effects that a hurricane, an extreme weather event, can have on a community. The memories of the devastation caused recently by Hurricane Irma as well as the six hurricanes in the span of two years (from 2014 to 2015) are still fresh in everyone’s mind. Downed trees, flooded streets, homes demolished, and power outages are just some of the hardships caused by extreme weather events.

Depending on the severity of the event, restoration efforts can take days, weeks, months, or—in the case of Hurricane Katrina—even years. For their part, utility companies are compelled by their customers to restore power as quickly and as safely as possible. Year-round, utilities seek to continually upgrade and harden their power systems to improve reliability and resiliency specifically against extreme weather conditions. Once a storm hits, utilities closely monitor outages and determine when conditions are safe for crews to begin restoration efforts. 

 

Damage to local distribution lines following Hurricane Irma in Florida.

 

As a manager in our Power group, I focus on transmission, distribution, and substation engineering in hurricane wind zones. I understand that strengthening our infrastructure is a key component for improving the reliability of a power system. Utility engineers design power systems to meet or exceed the standards set in the National Electric Safety Code (NESC), which is the standard for safely installing, operating, and maintaining electric systems in addition to regional, local, and OSHA requirements. In Florida, utilities specifically design their infrastructure to sustain hurricane-force winds. But what other key initiatives are we doing to make sure our utilities are resilient?

Here are four:

  1. Upgrading structures. To further harden existing systems, many utilities in Florida have been replacing existing wood distribution and transmission structures with concrete or steel structures, which are more resilient against hurricane wind loading.
  2. Redundant systems. Smart utility system designers will include redundancy into the system so that when an outage occurs, power can be rerouted to isolate the fault and restore power quickly.
  3. Improvements in technology. Recently, “disconnect switches,” a key component in reliable and resilient systems, have become automated. By upgrading from manual disconnect switches to automatic feeder switches (AFS), the automated switches can be operated remotely—which not only reduces restoration time but also improves safety.
  4. Vegetation plans. Historically, many faults resulting in power outages are due to vegetation interfering with the power system. A year-round, comprehensive vegetation management plan is key, but it is even more significant to evaluate possible issues prior to the start of hurricane season or other storm events. Patrolling power lines and remediating problem vegetation is critical to minimizing the probability of outages caused by vegetation. By trimming/removing problematic vegetation, utility owners can further reduce the likelihood of potential power outages.

When customers lose power during a storm event, the restoration time for power to return is first and foremost on their minds. Before a storm makes landfall, utilities are preparing for restoration by transporting materials to forecast areas of need, mobilizing crews, and monitoring outages.

 

Damage to local distribution lines following Hurricane Irma in Florida.

 

Storm restoration begins once it is safe for utility employees to navigate the streets and assess damage to the power system. Based on the prioritization of critical customers, non-construction employees will patrol the power lines and identify what facilities and equipment need repair or replacement. Repairs can range from a blown fuse in a disconnect switch to the repair of an entire circuit. However, having a robust storm-restoration plan in place and outlining what to do in advance of, during, and after an extreme weather event will significantly improve restoration time and cost.

By hardening the system, taking advantage of new technology, and employing a comprehensive vegetation management system, owners can significantly improve reliability and resiliency before, during, and after extreme weather events.

About the Author

Chad Renshaw

Chad Renshaw spends most of his time working on transmission, distribution, and substation engineering in hurricane wind zones. He specializes in concrete transmission structures, but he’s also well versed in wood and steel. Recently, Chad and his team are inspecting transmission structures using drones.

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