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America’s Substations are getting ‘Hardened’
Almost 300,000 miles of high voltage transmission lines and about 2 million miles of low voltage distribution lines serve around 300 million US customers. Those are the ‘pipes’ that route the power to millions of utility customers in the US. But the increasingly complex systems that control and protect the nation’s $400 billion electric power network reside in fewer than 80,000 major substations. Malfunction of any of these substations can cause customers to lose power, if only for a few seconds. More serious incidents can cause major outages involving thousands, maybe millions of customers and lasting for hours, even days.
As substations become more sophisticated, they’ve also grown more vulnerable to whims of terrorists, Mother Nature, and cyberspace. In response, the power industry is rapidly implementing strategies for substation hardening and resilience.
Bullets, Bombs and Bytes
For the last decade, the power industry has had to seriously consider potential damage by acts of terrorism. That concern deepened after a 2014 study by the Federal Energy Regulatory Commission (FERC) concluded that a coordinated attack on just nine key substations could knock out power throughout the United States, in some regions possibly for weeks or even months. The study wasn’t based just on hypotheticals, it was initiated by an actual sniper attack on Pacific Gas and Electric Company’s 500kV Metcalf substation near San Jose, California in April 2013. Over one hundred .30 caliber rounds disabled 17 transformers. More recently, in September 2016 a gunman knocked out a substation in Utah, cutting off electricity to 13,000 customers for a day and forcing the utility to wait months for the station's ruined transformer to be repaired or replaced.
So far, no major explosive attack on a substation has occurred in the US, although several attempts have been made but failed before significant damage could be done.
A much more widespread bomb attack would be the high-altitude detonation of a nuclear device. The intense heat from the blast and almost instantaneous expansion of the atmosphere would cause the ionosphere to suddenly accelerate outwardly. In turn the accelerated charged particles in the ionosphere would produce an electromagnetic pulse (EMP) that could induce damaging voltages and currents in power lines and their control circuitry. Both the Russians and the US have experimented with this mode of attack. They’ve proved that it works!
Surge arrestors and the right control wire and cable shielding can help to mitigate the impacts of EMP.
Hardening Against Cyber and Physical Attack
Bullets and explosives aren’t the only means for crackpots and terrorists to attack the power system. As substation automation grows more sophisticated, the potential threat of cyber-attack has grown. Substations offer many points of virus entry into the power system. And we know that a cyber weapon can be effective - as witness the Stuxnet worm attack on the Iranian nuclear plant in 2014.
The North American Electric Reliability Corporation (NERC) is helping to develop critical infrastructure protection (CIP) standards for the US electric power industry. Cybersecurity and physical security are both high priority for CIP development. However, due to actual attacks and the present state of the world, the focus has increased on physical security. And no wonder: for over a century, critical substation components were, at best, guarded only by a see-through, shoot-through chain-link fence. That’s changing.
Suppliers are already offering bullet-proof walls that can be erected around existing facilities. And ballistic shielding is available for individual transformers. We can expect plenty of innovation as manufacturers see new markets due to the new standards for physical security of critical substations enacted by FERC. In another Federal move, Idaho National Laboratory developed a ballistic barrier system to protect substations from threats such as bullets, vehicles laden with explosives and tornado-strength winds.
Transformer Protection Barrier, designed by Idaho National Laboratory. Multiple units can be linked together to form a complete ballistic barrier against a variety of threats.
Natural causes can be just as damaging as anything humans can do. In 1971, the Sylmar AC/DC converter station in Southern California was pretty much destroyed following a 6.7 magnitude earthquake. Superstorm Sandy caused a quarter million customers to lose power in Manhattan after a fiery explosion at a flooded substation in 2012. In 2011, the brick substation in Joplin Missouri was demolished by an EF5 multiple vortex tornado. There are many more examples. And according to the DOE, the number of outages resulting from extreme weather is expected to rise as climate change increases the frequency and intensity of hurricanes, blizzards, floods and other extreme events.
Observed outages on the bulk electric system, 1992-2012. (US Energy Information Administration)
Floods and Storm Surge Protection
Some coastal utilities, such as Con Ed are building dams and walls to protect substations against storm surge. Others, such as Centerpoint Energy has done, are raising transformers, control houses and other major substation components above the flood plain.
Con Edison has created a hardening plan for flood protection of aboveground substations. Note the surrounding dam wall. Courtesy of Transmission and Distribution World.
A substation near downtown Galveston, Texas, was elevated on concrete “stilts” to protect it against future storm surges. Courtesy of Transmission and Distribution World.
Protection panels on the new lifting platforms can be raised above expected flood levels. Courtesy of Transmission and Distribution World.
And Here Comes the Sun
Outer space even gets into the act as the news media periodically warns of impending solar storms that can produce electromagnetic fields intense enough to knock out large portions of the North American power grid. The news people remind us of March 13, 1989, when millions of people in the province of Quebec, Canada found themselves in a 12-hour blackout. At the same time, across the United States from coast to coast, over 200 power grid problems erupted. These outages followed a billion-ton cloud of gas ejected from the sun at a million miles an hour striking the Earth's magnetic field. As a result, large, destructive geomagnetically induced currents (GIC) flowed through the neutral terminals of large substation transformers.
Standards have been put in place by NERC for equipment modifications and procedures and most, but not all, experts think we’ve got the problem licked. But, no matter what, the media will still scream alarm when solar flares occur.
Devil’s in the Details
Along with flood walls, elevated control panels and bullet proof shields, effective hardening requires close attention to less visible substation components. Adequate shielding and grounding and the right insulation on control room wiring can make the difference between an annoyance or a shutdown during flood condition. Resiliency, getting the power back on after a substation outage, is greatly affected by the ease of replacing and splicing of wire and cable. Here again, shielding and wiring choices can make all the difference.
Southwire can help!