html{display:none} A Country on Their Own | Schweitzer Engineering Laboratories
Part Two

A Country on Their Own

They were doing the best they could with what they had.

In a small section of southeastern Europe, at the crossroads into Asia, sits the Republic of Georgia. Rolling green hills, wind-worn villages, and a growing population are encompassed by the rugged and imposing Caucasus Mountains. In Greek mythology, these mountains are said to be one of the pillars holding up the world.

To the north, east, and south, Georgia is surrounded by Russia, Azerbaijan, Armenia, and Turkey. To the west, the land stretches into beaches that meet the turbulent Black Sea.

“Whoever visits Georgia once will never forget it,” said Ia Aburjania, who recently joined the team at SEL as a customer service representative in the Georgia office. “There is always something: the food, the public holidays where everyone gathers in the streets, the mountains, and the sea.”

Over one million people live within the mazelike, cobblestoned streets of Tbilisi, the country’s capital, where the statue of the powerful Mother Georgia watches over them day and night. In one hand she holds wine, for those who come as friends; in the other, a sword, for those who come as enemies.

Tbilisi is a stark contrast of traditional and modern. Interspersed between space-age architecture are buildings that look like they might collapse.

Georgia is a country of contrasts. Old and new co-exist in a unique blend of Caucasus Mountain villages, Black Sea beaches, and diverse architecture.

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This mix of old and new was no different when it came to Georgia’s power system, specifically, its substations—the large fenced yards that house the electrical equipment necessary to lower voltages traveling to consumers.

Next to the few newer, digital relays were sixty- to seventy-year-old electromechanical relays, covered in plastic cases that had once been clear and white, but now were scuffed and yellowing with age. These older relays made electric power reliability difficult to achieve, and for a long time the country had to live with the fact that electric power was not always a guarantee.

Because most of the relays in Georgia’s substations were still electromechanical, everything needed to be manually monitored and maintained.

John Needs, an SEL regional technical manager in the U.K., visited many of these substations during the project.

“It’s actually quite surprising,” said Needs. “You’ve got all these substations and they’re manned—24 hours a day! That’s unusual for U.S. or European substations because everything is all automated now. I mean, some of this equipment was ancient—really ancient. And they’re still being maintained and working. It was amazing.”

Old electromechanical relays populated every substation in Georgia, making overall power system stability difficult.

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The Georgian power system includes 92 substations scattered throughout the country. The massive hydropower plant in the far west—Enguri—is the dominant generator in Georgia and the tallest arch dam in Europe, rising 271.5 m (891 ft), just under the height of the Eiffel Tower. With an installed capacity of 1,300 MW and an operational capacity of 1,200 MW, Enguri alone is responsible for more than 40 percent of the total electricity generated in Georgia.

All of this is operated by the country’s power utility, GSE. GSE headquarters is in Tbilisi at the National Control Center. There, dispatch operators control power system operations and ensure proper operation of all transmission lines both in normal conditions and in emergencies. The transmission network consists of a mix of 500, 400, 330, 220, 110, and 35 kV lines. Within this network is a particular 500 kV circuit called The Backbone.

For years, challenging terrain and high strain along The Backbone have been the cause of countless blackouts and a source of instability in the Georgian power system.

“The blackouts had been going on for twenty years,” said Didbaridze. “The situation in the last ten to fifteen years in Georgia’s energy grid was very difficult.”

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Before Georgia claimed their independence as a country in the early 1990s, the territory was part of a large, interconnected electric power system in the Soviet Union. When the Soviet Union collapsed, so did the interconnected system; it split.

“What was once a very well-designed and solid network was now very weak,” said Rodas. “Not one of these new countries had a solution for the situation they found themselves in.”

This fractured system took its toll on Georgia. In the years leading up to 2010, there were 8–14 partial blackouts and 2–5 total blackouts every year. The loss of interconnection led to unintentional weak spots and unforeseen consequences because there were no longer alternate sources to compensate for the outage of certain lines.

“But you know, they were a country on their own now,” said Dolezilek. “They were doing the best they could with what they had.”

“If That One Goes Down, They All Go Down”

“We have a structure that is not optimal,” said Siegmar Leutloff, a GSE engineer. “It is a parallel backbone system with no meshing.”

The Backbone. There’s a reason it’s so critical.

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Alexander “Aleko” Didbaridze

International Projects Technical Manager,
GSE

The Backbone is a transmission line circuit that runs west to east. It carries electric power from the Enguri hydropower plant in the west all the way across the country, through the challenging terrain of the Caucasus mountains, to serve the most populated area in Georgia with the highest load demand, Tbilisi.

There are two key substations along The Backbone, Zestaponi and Ksani. There are also two key transmission lines, 500 kV Imereti and 500 kV Kartli II. Running parallel is a 220 kV transmission line circuit, which connects to The Backbone at both the Zestaponi and Ksani substations.

If a 500 kV line on that network goes down, the whole system goes down.

The Backbone is one of Georgia’s critical transmission line circuits. It is responsible for carrying electric power across the country, through some of the most rugged and imposing terrain in the Caucasus Mountains, to Tbilisi.

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The reliability and load flow in Georgia’s power system is highly seasonal. During the winter months, hydropower output at Enguri is low, so GSE operates one of the thermal generation plants near Tbilisi. This means the power flow along The Backbone is minimal, therefore, blackouts typically aren’t an issue.

But summer is different.

In warmer months, the Enguri hydropower plant operates at peak capacity with excess hydropower output. Hydropower generation is significantly less expensive than thermal, so GSE relies on Enguri to generate the majority of electricity for Tbilisi. That means it is the sole responsibility of The Backbone to transfer all that hydropower from Enguri across the country to Tbilisi, increasing the power flow and the strain along this circuit.

“The amount of generation in Georgia has never been a problem,” said Needs, “but it’s all on the west side of the country, and Tbilisi and all the major load centers are on the east side. They couldn’t transmit all that power reliably, especially during high usage times. Tbilisi was just taking too much power for the power lines to handle, and they would trip out.”

There are two recurring event scenarios on The Backbone that cause the majority of the blackouts. In both situations, a fault occurs on one of the main 500 kV transmission lines, and the line trips. Once that happens, the power from that 500 kV line tries to reroute through the parallel 220 kV circuit. However, the 220 kV circuit is not capable of carrying that much power, so it overloads. The old electromechanical relays in these key substations see the overloading and send out their own trip signals to protect the 220 kV line from damage. But because the system has no way to balance load, this action cascades into a larger outage and causes all of Tbilisi to blackout.

“The blackouts became something of a normal occurrence,” said Aburjania. “You just got used to them.”

Blackouts can also put an area or country at a serious disadvantage.

“The financial burden to that and other countries when there’s a total blackout is measurable and real,” said Dolezilek.

Yes, during a blackout the energy grid is stable and protected from dangerous power flow levels, but it’s also unable to deliver energy, leaving people to face the results of a lack of power. Food spoils without refrigeration. Production shuts down. Financial services come to a halt. People can’t cook with electric appliances. Toilets, sinks, and showers no longer operate. There is no more air conditioning and no more heating. The availability of modern medical care is compromised. The list goes on.

Not only that, but it’s also tough on the power system equipment. Every time a system experiences a fault or blackout, the lifespan of transformers, generators, and other equipment goes down. These are vital pieces of a power system that are incredibly expensive to replace.

Georgia’s energy instability was also inhibiting the goal of expanding into European markets. GSE wanted their country to be a hub for clean energy production, and they wanted to export that energy into Europe as well as allow other countries to use their transmission lines to pass that energy. But they needed to be able to comply with the requirements from the European markets.

“Energy stability was a major factor,” said Didbaridze. “When we started looking into interchanging energy with neighboring countries, the problem of blackouts became even more important to us.”

The Day Everything Changed

August 26, 2010.

Already, there had been three major blackouts that year in Georgia. The day was hot and humid. Load demand and usage in Tbilisi was high. As usual, the Enguri hydropower plant was generating the main source of energy. Strain on The Backbone was at its peak.

All of a sudden, there was a fault on the 500 kV Kartli II line; it tripped. All the power immediately rerouted through the 220 kV parallel circuit. It was now operating at 150 percent of its rated capacity. Too much. This circuit tripped at Liakvi substation, creating two islands in the Georgian power system—one on the west and one on the east.

The generators in the western region were operating with too much frequency because there was not enough load—it had all been disconnected. The generators tripped offline.

At the same time, the split caused the generators in the eastern region to overload. Everything tripped offline.

A complete system blackout. Not just Tbilisi. The entire country shut down. Military bases, hospitals, the airport, the house of the president. Nobody had power, and the gravity of the situation began to set in.

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“This was now a national issue,” said Rodas. “This event triggered the need for everyone to come together and create a system, as a priority, to stop this from happening again.”

The Ministry of Energy got involved, expressing concern over the severity of the recent blackouts. The events had compromised national security and the stability of the economy.

August 26 was the turning point. And now there was a deadline. GSE needed to have a solution in place by the next summer. The message was clear: this cannot happen again.