Hulking transformers prove a challenge for vulnerable grid

Source: Blake Sobczak and Peter Behr, E&E reporters • Posted: Tuesday, November 24, 2015

William Fehrman had a 450,000-pound puzzle on his hands.

A large power transformer in the utility executive’s service territory was sputtering toward the end of its useful life. Fehrman, president and CEO of MidAmerican Energy Co. in Des Moines, Iowa, knew he needed to replace the cumbersome piece of equipment, so he jumped on the chance to practice speeding up the process.

“Moving the new one to [the substation] required rail, rigging and a variety of permits and such — so we really tested ourselves to see how fast we could do it,” said Fehrman, who estimates that MidAmerican moves a large power transformer, or LPT, about once a year.

Earlier this year, Fehrman’s team proved it could cut the typical three-month replacement process in half. The bad news: It still took 45 days to put in place a transformer that could be used to restore power on a segment of the interstate grid.

For a major U.S. city, even a few weeks without power would be an unprecedented economic and human calamity. Cutting the delivery schedules for key grid components is still a major challenge for the industry, as a nationwide security exercise showed last week.

At least 350 utilities and 4,000 people took part in the GridEx III “war games” that played out last Wednesday and Thursday, according to the event’s chief organizer, the North American Electric Reliability Corp.

The exercise was designed to test the cyber and physical security readiness of the North American electric grid, including the availability and mobility of large power transformers (EnergyWire, Nov. 20).

During the extreme GridEx scenario, “the number of spare transformers would still have been sufficient,” said Scott Aaronson, managing director for national security policy at the Edison Electric Institute, which represents investor-owned utilities in North America. “The capacity to move them into place and re-engineer the system under duress is something that we are continuing to improve, and I think is going to benefit greatly from some of the lessons learned coming out of this exercise.”

Craig Stiegemeier, transformer technology director for ABB in North America, took part in this year’s GridEx and said it highlighted weak points in the supply chain.

Stiegemeier, whose company manufactures transformers, pointed out that the scenario didn’t exhaust all of ABB’s resources, but it wasn’t for lack of severity.

“I would imagine that if the event was as widespread as what it was supposed to get to, that would really do a number on what’s available” for assessing and fixing key pieces of equipment, he said. The two-day exercise didn’t last long enough to reach that point, although he said it still heightened participants’ awareness of key vulnerabilities.

ABB has urged Congress and the Obama administration to support creation of a strategic reserve of high-voltage transformers to speed recovery from catastrophic losses in the event of terrorist attacks or extreme solar storms.

“If there was a strategic [transformer] reserve that was rapidly movable, it would have aided greatly in recovering from a large-scale attack on the grid,” he said.

MidAmerican has shared the lessons learned from its own real-world effort to halve the amount of time needed for transformer shipments, according to Fehrman.

“In this case, it was really a matter of having exceptional teams on all of the handoffs and making sure we know well ahead of time what it is we’re dealing with,” he told EnergyWire.

“While moving a transformer is a challenge, it’s not a moonshot,” Fehrman added.

Have a spare?

Moving a large power transformer a few hundred miles is not for the faint of heart. For starters, LPTs can tip the scales at 400,000 pounds or more, about the weight of a blue whale. They’re a massive tangle of costly copper and steel, heavy enough to endanger old bridges and too bulky to squeeze through many rail tunnels. They aren’t supposed to be moved on an incline, meaning they often trace circuitous paths to their final destinations.

Transformers are expensive — $3 million to $5 million apiece by Congressional Research Service estimates — and may be custom-designed to work in just one particular substation.

It’s no wonder large power transformers were singled out as the most vulnerable component in the bulk electric power system during security reviews after the Sept. 11, 2001, terrorist attacks.

Before a utility can think about packaging and shipping a transformer, however, it needs to have one on hand. Government reports warn that the existing inventory of spare transformers might not be enough to replace widespread equipment losses.

“Despite expanded efforts by industry and federal regulators, current programs to address the [transformer] vulnerability may not be adequate to address the security and reliability concerns associated with simultaneous failures of multiple high-voltage transformers,” the Energy Department’s Quadrennial Energy Review cautioned.

The electricity industry has set up a spare transformer program to counteract long manufacturing lead times. If a major transmission company faces a coordinated terror attack on multiple substations, the logic goes, other utilities can pitch in extra transformers at short notice to prevent an outage from dragging on for months. One industry official likened the Spare Transformer Equipment Program (STEP) to an organ donor program that only kicks in during do-or-die emergencies. Another initiative, the SpareConnect program, offers utilities a confidential platform to request transformers and related equipment from one another in other circumstances.

EEI and several member utilities participating in the STEP program have declined to specify how many extra transformers are accessible nationwide, citing security concerns. Officials acknowledge that the adequacy of U.S. grid operators’ responses to transformer threats is not publicly documented.

“The industry has made some progress toward building an inventory of spares, but these efforts could be overwhelmed by a large attack,” the QER noted, citing a National Research Council study referring to the electricity sector’s effort.

A spare transformer program “alone is not sufficient to address the vulnerabilities that the United States faces in the event of a large physical attack,” the report concluded.

Guns and grenades aren’t the only ways to damage LPTs — utilities also have to consider space weather and hackers.

The Federal Energy Regulatory Commission has approved mandatory reliability standards for cybersecurity defenses and physical protection of grid substations and also issued the first of two orders on defenses against rogue ground currents from a “once in a century” solar storm. A proposed second-phase order deals specifically with solar geomagnetic disturbances that could threaten transformers that “step up” voltage so electricity can travel more efficiently over transmission lines.

The range of threats may be driving some utilities to pursue backup plans beyond STEP. A group of energy companies headed by Columbus, Ohio-based American Electric Power Co. Inc. has proposed creating a new company called Grid Assurance that would purchase and maintain an inventory of high-voltage transformers and other critical spare transmission equipment.

Transmission grid companies that signed a subscriber agreement with Grid Assurance and paid a fee covering operating costs could purchase equipment if needed following a defined “catastrophic” event, including physical and cyber attacks and solar storms.

Grid Assurance spokeswoman Melissa McHenry said industry has shown “significant interest” in the program as it seeks subscription agreements and supporting rulings from the Federal Energy Regulatory Commission.

It’s complicated

From a logistical standpoint, having extra transformers ready is only part of the battle — utilities must also find a way to get LPTs from point A to point B.

That’s where the freight rail industry steps in. Moving transformers is a delicate operation, even on the sturdiest tracks. “We just don’t plop a transformer with our grain cars and send it off. We have a special train, a special crew,” said Tiana Draper, director of marketing for CSX Corp.’s Waste & Equipment group.

Most rail cars cannot handle a load any heavier than 200,000 pounds. So LPTs have to move on special rail cars that partially suspend them between two platforms, distributing the weight across many wheels. There are only about 30 such “Schnabel cars” in all of North America, according to the latest available estimates.

Raw tonnage isn’t the only challenge. Transformers’ odd proportions make them susceptible to clipping low-hanging power lines or tree branches en route.

When preparing to move LPTs on its network, rail giant CSX calls in its “clearance bureau” to scan the proposed route with lasers and ensure it’s passable. Engineers pore over sketches of certain curves and inclines to make sure the equipment won’t be damaged.

“It sounds complicated and it is complicated, but we do it every day” for “dimensional loads,” Draper said. That category includes wind turbines, huge heat exchangers and large power transformers, among other items.

“We know every single dimension of the routes that we would potentially put [transfomers] on,” she said.

CSX officials met recently with federal regulators at the Department of Energy to review transportation planning in the event of a grid disaster.

A DOE spokesman declined to detail what was discussed in the closed-door meeting with rail industry representatives but pointed out that the agency is currently working on an update to a 2014 study of large power transformers and the electric grid.

Stress test

The rail industry puts its own infrastructure to the test in an annual simulation similar to the electricity sector’s biennial GridEx war games. The latest rail security exercise took place in October, according to Thomas Farmer, assistant vice president of security for the Association of American Railroads, a leading industry trade group.

AAR facilitated coordination with the Edison Electric Institute for this year’s program, Farmer said. MidAmerican was among the power companies to observe the daylong event.

“We’ve now twice exercised scenarios where we would be called upon to provide support for the electrical industry in the event that there was significant damage or destruction of one or more transformers,” Farmer said.

The AAR security official declined to share the specific scenario for this year’s exercise but noted that, like GridEx, it involved both physical and cyber elements.

While not commenting specifically on the security exercise, Draper pointed out that CSX has “very sophisticated” business continuity plans for extreme conditions, such as an extended power failure at CSX’s Jacksonville, Fla., headquarters or outages along key routes.

“We have our diesel engines, so the power to pull a unit is still there — the power that we need along the line would be for signals,” she said. In an electric emergency, CSX would operate as it does in existing rural “dark territory,” where there are few or no signals due to low traffic.

Transformers can also be shipped by truck and typically move that way for the first and last legs of their journey. But the largest high-voltage units that are essential to the transmission system typically must be disassembled first to move in this way, then reassembled at the new site.

ABB has produced a working prototype of a unit that can be shipped in smaller chunks and assembled on-site in a week’s time. That kind of portable LPT would make trucking a viable option for long-haul transport.