Last week, a monkey switched off Kenya’s entire national grid for three hours. The problem wasn’t that nothing worked; it was that everything worked too well.
At half past 11 on June 7th, a curious vervet monkey beat the electric fence and other security features to jump onto the roof of the Gitaru power station.
It then fell on a transformer, tripping it. With one main transformer down, other machines at the power station overloaded, each trying to compensate for the loss of the other. Eventually, the entire plant went off, robbing 180 MW from the grid. The same thing that had happened inside happened across the grid, as other systems and parts tried to compensate. In a matter of seconds, the entire grid was off, and it took three painstaking hours and some extra muscle to bring them back up.
What the blackout monkey triggered at Gitaru is called a cascading power failure. Think of it like a domino effect in a network. When one critical element is suddenly removed from a stable system, the next one moves in to fill that hole, followed by the next and so on. When it’s an entire network, it’s even worse.
The electric grid is an orderly network with many critical nodes. This means that if one fails, the others could switch off in a cascade, the failure of each one triggering the failure of the next in line. Compare that to a social network such as say, Facebook. The connections between you and everyone else are quite random. Each person’s network is different, but we are all connected. Since such networks are randomly structured, if a critical point fails, there is a higher chance it can be caught on time and solved. If you start some BS on your profile, for example, it can be/is isolated just to the people who have the unfortunate luck of being your friends.
On an orderly network, it would go viral faster than you could delete it. And that’s what happened. On an orderly, centralized network like our electricity grid, there are a relatively small number of points of potential major failure.
When you plug in your phone to charge at home, this long line of components comes into play. They stretch all the way from the power station (s), through several substations, to the socket. It’s (normally) a stable and reliable system, if everything works right and no one tries monkey business. See, the Gitaru Power Station is the biggest station in East Africa in effective capacity. It supplies nearly 10 percent of Kenya’s power, meaning that it’s going off left a huge hole in the system. It can theoretically produce 225 MW but the most it has ever done was 222 MW on 22nd May, 2002. One evening in November 2006, it nearly reached this record with a 220 MW recording.
The electric grid is such a delicate system that when you finish a new power generation project, say the Turkana Wind Project, you can’t simply plug it into the grid. Every new source of power has to be evaluated to ensure it won’t overload the existing infrastructure. It’s the same for taking any power station out, even for routine maintenance. You simply can’t turn it off because there will be chaos. But stuff happens, so the entire grid is fit in with failsafe mechanisms.
But how didn’t any of them stop this before it escalated?
In fact, it did. They all did. That’s the problem.
A power grid is an expensive installation, not even counting its importance to the Kenyan economy. To protect it from going up in smoke, it is fitted with protection systems such as circuit breakers. They are all over, including in your meter at home and the main switch. If anything happens, such as power increasing too fast or a short-circuit, then those breakers switch off that part of the grid to protect the rest of it from that nonsense.
And that is exactly why a cascading failure is possible.
Protection systems such as circuit breakers can’t tell the difference between a short-circuit and a sudden drop in voltage caused by say, a curious vervet monkey. So when the transformer switched itself off to protect the rest of the line, the interconnected machines did the same, and the next, and the next, and then chaos. It’s like the ripples of a rock when it lands in a pond. They start small and then grow slowly towards world domination.
But shouldn’t there be failsafe mechanisms for failsafe mechanisms?
Of course you can’t plan for vervet monkeys and their disastrous curiosity, but if such a fault is caught in time, some parts of the grid can be switched off to cut the cascade. But that’s easier said than done, even in automated systems.
Think of it like this, a control only works if the failure reaches it, but that negative information, for example, travels as fast as the control signal needed to stop it. It’s like running a relay match where the other person in your team can’t move until you reach her and pass the baton. But the speed with which that handover happens is the same or slower than that at which the other guys are also making their exchange. By the time the control signal works, the failure has already crossed. There is mitigation to this too; such as alarms and good luck. But even they sometimes decide to go for lunch.
A similarly ridiculous blackout happened in Ohio in Northern America in 2003. The First Energy power plants managers had not trimmed the trees along several power lines. As the day temperatures increased, the lines sagged. Four of them touched the trees and immediately tripped their circuit breaks. The alarm meant to warn the power plant of failures like this itself failed to work. A few more circuit breakers joined the party and then there was a large drop in voltage and voila! A major line was then tripped, and before long 50 million people were in the dark. Not trimming a few trees ended up switching off a total load of 61.8 gW.
Four years ago, two consecutive cascading power failures in Northern India left 600 million people without power for two days. Electricity was restored within 15 hours on the first day, only for another fault near the Taj Mahal to lead to a second failure the next day. Just when you think it’s over. The year before that, another cascading event had happened but not with power, but with internet connection. A 75-year-old Georgian woman scavenging for copper for scrap hit and severed a major fiber optic cable heading to Armenia. Later nicknamed “the spade-hacker”, her single action cut off all internet connection to Armenia, some parts of Georgia and Azerbaijan for five hours. Talk of having a bad day!
When the entire electricity grid is off and the monkey removed, you need to bring in extra muscle to jump-start the power stations.
In the total absence of grid power we require a black start to bootstrap the grid back into operation. Meaning an independent generator
Mrs. Kigen (@DeeKerubo) June 7, 2016
Once the generating station is back on, key transmission lines between major substations are energised. This is tricky and usually fails
Mrs. Kigen (@DeeKerubo) June 7, 2016
Despite our exceedingly lucky monkey becoming a global celebrity, animal attacks on electric grids are not uncommon. In fact, there is an entire database dedicated to animal attacks-primarily squirrels-on the American electricity grid. Our true enemies are furry and four-legged; those are the true terrorists, guys.
Vervet monkeys seem to have a particularly unlucky relationship with electricity. Electricity pylons feature highly on the list of things that kill them. Almost all others are less the monkey’s fault: dogs, vehicles, and guns, but with pylons, it’s like the monkeys have a death wish. Or maybe a dare. Maybe the Gitaru blackout monkey was responding to a dare. Or he was trying to impress a girl.
I wonder what he is up to now.
Unconfirmed reports indicate that the monkey electrocuted at Gitaru may have been involved in a side chick saga.. pic.twitter.com/mqLfSb1MTn
Deluxe Nyeuthi (@Buggz79) June 7, 2016
Featured Image of vervet monkey in Kruger NP. By Wegmann. [Source]
One story is good,
till Another is told.
Last modified: May 12, 2020