Tony Sleva, SEA Consulting Services
Editor’s note: Sleva contacted EL&P in response to our Sept. cover article “Power security in a bottle: Who pays for the safety salve?” His short note–included here as a sidebar–intrigued us, and we offered him this guest commentary forum to more fully develop his argument.
The Sept. 11, 2001, attack on the World Trade Center should have been a wake-up call to designers and operators of America’s infrastructure. Al-Queda operatives demonstrated that they have the time and talent to study technical systems, uncover weak points, and initiate actions that will exploit those weaknesses.
Recently published articles in trade publications, including EL&P’s Sept. story, have discussed the need for utilities to identify the most critical equipment, develop defensive systems for critical assets, and establish “smart” controls that cannot be manipulated outside of normal operating ranges.
There is still concern, however, that utilities and independent system operators have not progressed to the point that they begin to think like terrorists. They are still thinking like designers of systems that will not be targeted by terrorists. If you were a small group of disenfranchised fanatics who wanted to make a name for yourself by causing a blackout that included large areas of the United States, what would you do?
Would you detonate explosives at randomly selected substations and transmission line towers? Twenty years ago, you might have tried that, but let’s think like a modern terrorist.
Would you go online and accumulate as much information as possible about the San Francisco Blackout of 1998? Would you study the Western Area disturbances of 1996? Would you obtain copies of IEEE papers that present technical advances that have been utilized to maintain power system stability during power system faults? Would you purchase textbooks that present power system stability considerations? Would you purchase maps that show transmission systems of the U.S. and Canada map? In other words, would you think like an engineer?
I think the answer to each of the preceding questions is yes. In fact, I’d be surprised to learn that terrorists haven’t been accumulating information related to the design and operation of our electric transmission networks.
Down to brass tacks
Let’s look at a specific example. With the existing transmission system grid, when a three phase fault (short circuit) occurs on a 500 kV transmission line, grid voltage drops to 250 kV at all 500 kV locations within 100 circuit miles. The significance is that one, three phase, 500 kV fault can potentially blackout the entire Mid-Atlantic region. If conditions are right, the blackout could extend beyond the Mid-Atlantic region. Similar scenarios can be theorized for California, the Pacific Northwest, and other regions of the United States.
Additionally, the features which prevent blackouts are protective relay schemes, which have been designed to clear three phase faults very quickly. (It is generally acknowledged that if a three phase fault persists on any 345 kV, 500 kV or 765 kV component for 250 milliseconds, grid instability will occur.) Therefore, rapid fault clearing is the feature that terrorists will try to compromise unless utilities change their design and operating practices to make sabotage of protective systems and related substation components much more difficult than it is today.
Prior to Sept 11, 2001, substation security was not the priority it needs to be today. Few substations had any intrusion detection. Many cabinet doors in substations were unlocked and those that were locked could be opened by common keys. Operators at manned substations did not fully check credentials.
Since Sept. 11, 2001, some utilities have improved substation security, but much remains to be done. In the near term, utilities can install redundant intrusion detection in all major substations and harden substations so that no protective function can be disabled in less time than it takes for security personnel to respond to an intrusion alarm at a substation.
A safe and secure future?
In the long term, redundant, hardened, high voltage transmission grids should be developed. Hardening should include barriers to reduce visibility and unauthorized access to substations; security grade, group-keyed locks; and intrusion detection that is focused on critical components.
Redundancy can be accomplished by re-configuring the existing transmission grid into several overlaid power grids with AC/DC/AC isolators between the grids so that the impact of any terrorist activity or naturally occurring transient can be confined to a predetermined geographical area.
The bottom line is that every electrical engineer who understands the link between power system stability, protective relaying, and substation design has knowledge that can be used to blackout wide portions of the United States.
An alternative point of view is that every electrical engineer has some knowledge that can be used to counteract terrorist activity and prevent widespread blackouts. Our goal must be to use our combined electrical knowledge to harden transmission systems so that one or two determined individuals cannot cause the collapse of wide areas of the transmission network.
Sleva is a principal engineer at SEA Consulting Services in Cranbury, N.J. He can be reached at 609-409-9790 or by e-mail: firstname.lastname@example.org.
October 2, 2001
Thank you for printing the article about power security in your Sept. 2002 publication. The story, however, failed to recognize the greatest risk to electric power systems: One terrorist with limited electrical knowledge and tools available in any hardware store could cause a blackout the would stretch from Canada to Georgia, Illinois to the Atlantic Ocean.
Terrorists do not need explosives or coordinated attacks on multiple facilities to blackout electrical systems. All they need is 15 minutes of access to one of the major substations on the East Coast.
Tony Sleva, P.E.