By Rich Heidorn Jr.

How big was Hurricane Harvey?

So big that, even before it made landfall in Texas on Aug. 25, the National Weather Service was warning via Twitter that it was “unprecedented.”

“All impacts are unknown and beyond anything experienced,” NWS said. “Follow orders from officials to ensure safety.”

“If you follow the National Weather Service … on Twitter, there’s not usually a lot of hyperbole,” ERCOT CEO Bill Magness observed. “This one, you could tell, was like nothing they’d ever seen.”

There was no shortage of superlatives Tuesday as AEP Texas and CenterPoint Energy executives briefed ERCOT board members on the impact of the massive storm and their recovery from it.

The largest rain event in U.S. history dumped an estimated 40 to 60 inches of water in southeast Texas and southwest Louisiana — so much that the NWS had to add more colors to their maps to display the totals, Magness said.

Harvey made landfall at Rockport, Texas, as a Category 4 hurricane with winds of 130 mph on the evening of Aug. 25. The following day, it stalled over the state, picking up more moisture from the Gulf of Mexico before making a final landfall in Louisiana on Aug. 30.

While that meant unprecedented flooding, “from a transmission system perspective, the fact that it stopped was a good thing because … it was pretty much tearing up the transmission system that it passed through,” said Dan Woodfin, ERCOT’s senior director of system operations.

“When the storm was first coming onshore in the late hours of the 25th, we were having upwards of 20 … transmission elements tripping off each hour,” Woodfin continued.

“Our folks were running … N-1-1 studies — so, not just what it takes to be secure, but what it takes to be secure if the next line goes out. … Almost as soon as they finished the study, that line would trip and then we’d have to redo it for the next N-1-1.”

The ISO lost 12,000 MW of generation as gas-fired plants were evacuated or flooded and coal plants were derated as they switched to gas, their coal piles too sodden to burn. Wind turbines were shut down until the winds fell below their maximum operating speed. Other generators that could have run were unable to because they had no transmission.

Luckily, cooler weather meant that loads were as much as 25,000 MW lower than the week before.

The wind was the biggest problem for AEP Texas’ territory along the Gulf Coast, company President Judy Talavera told the ERCOT board. The utility, which had 220,000 customer meter outages at its peak, had to replace or repair 766 transmission structures and more than 5,700 distribution poles. Four million feet, or about 757 miles, of transmission and distribution conductor was replaced.

About 5,600 people, many from other utilities, helped the company restore 96% of outages within two weeks. “We drill for these types of events but those don’t quite prepare you for the actual event,” Talavera said.

For CenterPoint, which serves the Houston area, rain and lightning was the bigger challenge than wind, said Kenny Mercado, the company’s senior vice president of electric operations. The company recorded 42,000 lightning strikes. There were 150 tornado warnings in Houston, with more than 30 twisters touching down. The warnings created “a tremendous amount of anxiety” for residents, he said.

Seventeen substations were impacted; half of them knocked out of service, the other half inaccessible because of the flooding of the San Jacinto River, the Buffalo Bayou and other waterways.

The unrelenting rain limited the utility’s ability to restore service. In 2008, by contrast, “[Hurricane] Ike moved through the city and then we could go to work,” Mercado said.

Only 200,000 metered customers were out of service at any time. “But the problem was every day we’d get another 200,000. And the next day we’d get another 200,000, and the next day. So, it never ended until eventually we saw blue skies,” Mercado recalled.

Helped by Hardening, Technology

The good news, utility officials said, was that flood protections and technology added in recent years limited damage or increased the speed of the recovery.

A flood wall built after 2001’s Tropical Storm Allison protected the Grant substation, which serves the Texas Medical Center in Houston, the world’s largest medical complex.

A 50-MVA mobile substation installed on a church’s grounds allowed the company to restore power for 10,000 customers after 10 days. “They would have been out for probably another five days without it,” Mercado said. “So, the mobile substation technology that we have today is very, very valuable in terms of resiliency of the grid.”

Hundreds of intelligent grid devices saved 140,000 customer outages and provided critical situational awareness for restoration. Smart meters allowed the company to bill 700,000 accounts with actual readings and execute 45,000 orders remotely during the storm.

The companies resorted to drones to survey damage, airboats and amphibious vehicles to reach flooded substations and helicopters to move new transmission poles.

When standing water became a health hazard to workers, AEP outfitted their workers with mosquito nets to wear over their hardhats.

One technology that was not so successful for CenterPoint was its Tiger Dam, water-filled balloons that can function like sandbags but are quicker to deploy. “Didn’t have so much luck with it in Round 1,” Mercado said. “But it’s a skill set. We’re going to have to learn a little bit better how to do something in real time in terms of planning and preparation to look at those kinds of solutions.”

The company also plans to raise substation equipment to make it less susceptible to flooding.

Automated Calls, Facebook

The utilities also made use of newer means of communicating with their customers, including Twitter and Facebook.

Although 1.2 million CenterPoint customers lost service, “we only had 175,000 customers call … letting us know the power was out. … Only 67,000 customers used a live agent,” Mercado said. “So, the world’s changing. We’re seeing more and more automation take care of customers’ needs. Our power alert service technology pushed [text messages] out to 350,000 customers.”

CenterPoint’s website saw six times as much traffic as normal.

AEP Texas saw its Facebook followers more than double as the company made about 100 informational postings.

Public Support

Talavera said she was touched by the customers’ expressions of thanks to the restoration workers.

Residents offered workers meals, water and Gatorade, “wanting to show how much they appreciated them,” she said. “It’s really humbling. We know we provide an essential service and we’re proud of the efforts that were undertaken to restore service to our communities. But it’s certainly a partnership in working together with them.”