It was 2:30 in the morning when the first call came in to the National Control Center. Everyone stopped what they were doing as the dispatch manager relayed the message.
“Operator has arrived at Ksani substation. Begin final preparations.”
Everyone quickly got back to work.
It was June 16, 2011, in the Republic of Georgia. A small group of engineers had gathered in the National Control Center—the room that oversees the entire country’s electric power system. And they had a plan. In 30 minutes, they were going to intentionally create blackout conditions by simulating a fault, opening a breaker, and tripping one of the most important 500 kV transmission lines in the Georgian power system.
Most people, regardless of their industry, understand what a blackout is and understand the seriousness a situation like that demands. Georgian State Electrosystem (GSE), the country’s power utility, understood this better than most. However, they had just installed a new emergency control system, and they wanted to see it perform in a real emergency.
This new system came from Schweitzer Engineering Laboratories, Inc. (SEL).
Diego Rodas, an SEL engineer, paced the control room. He and his team had spent the last few months rapidly designing the emergency control system, writing relay logic, and simulating field tests, all to fit special requirements from GSE. He knew the system and the logic were sound. But a live test on a powerful transmission line always creates a certain amount of apprehension.
“It’s not that we didn’t trust our system to work,” said Rodas. “Even GSE. It’s not that they didn’t trust the system either. It’s just that there’s always a risk in doing anything live, especially with electric power.”
The transmission line in question is called Kartli II. It’s a 500 kV line that feeds power directly into the country’s capital, Tbilisi, where over 1.5 million people live and work. And it’s also part of something called “The Backbone” in the Georgian power system. If any transmission line on The Backbone goes down, the whole system goes down.
“We like to select the most critical line and the most critical situation in the network for a live test,” said Aleko Didbaridze, a GSE engineer.
The group spent the days leading up to June 16 preparing for the test.
“We had to get all sorts of permissions,” said Rodas. “Dispatch operators at GSE prepared a scheme—the situation—that we’d be testing. We had to check the equipment and verify our relay logic because the logic is what makes the decisions when there’s a fault, so it has to be right. It has to be exact.”
GSE sent an operator out to Ksani substation where the big Kartli II transmission line connects. His job was to wait for the signal from the National Control Center and then manually disconnect the power on Kartli II to initiate a blackout.
If everything went well, the emergency control system from SEL would detect the intentional fault, make a decision of where and how much load to shed, isolate the correct breaker, send a trip signal to that breaker, and prevent a country-wide blackout. All in less than 100 ms.
But if things didn’t go as planned, if the logic was wrong…
“The repercussions would’ve been pretty grand,” said Dave Dolezilek, International Technical Director at SEL. “The tension was definitely there.”
Inside the National Control Center, massive screens dominated the room, illuminating a display of the entire country’s power system—every transmission line, every substation, every generator, every power flow and voltage level. No matter what happened, everyone would see it.
For GSE, there was a lot of meaning attached to the outcome of this test. It was about more than whether or not the new system did its job. It was also carrying the weight of years and years of unreliable, unstable electric power in Georgia. Years of continuous blackouts. Years of financial burden.
Maybe it’s not fair for one test to have all that responsibility, all that buildup. But it did. Because for GSE, that test and that emergency control system signified the possibility of a new beginning for Georgia.
It was closing in on 3:00 a.m. Rodas checked the relay logic one last time and nodded his approval. Operators lowered the power thresholds. All eyes focused on the control screens, and everything was momentarily quiet.
Then the dispatch manager spoke into the phone.
“Cut the power.”