Transmission Failure Causes Nationwide Blackout in Argentina

“I can only convey to you that it is an event that no 1 could picture would transpire, given that there are many means to stay away from it,” states Raúl Bianchi Lastra, an electrical engineer at the Nationwide University of La Plata.  

Details about what might have took place appeared in a memo circulated on Sunday to energy distributors by Cammesa, the organization that coordinates the sale and supply of energy during Argentina. In this memo, Cammesa, in which the Argentine federal government retains a 20 p.c stake, handed on information from its initial review of the make a difference. (That memo was shared with IEEE Spectrum by many resources.)

According to the company, a small circuit disconnected a five hundred-kV transmission line that runs from the city of Colonia Elía to Belgrano, a neighborhood in Buenos Aires. And it seems that, at the exact time, an automated system disconnected yet another five hundred-kV line that runs from the city of Mercedes to Colonia Elía. The result in of that 2nd disconnection continues to be beneath investigation. A third five hundred-kV line, which generally connects the cities of Colonia Elía and Nueva Campana was taken out of provider on 18 April in purchase to relocate a tower.

Ricardo Rubio Barros, a lecturer in electromechanics at the Nationwide University of San Juan, states the SADI transmission community has experienced some instability in the earlier, but not to this degree. “There have been lots of SADI locations disconnected with partial blackouts owing to transmission faults, but in no way causing a finish SADI blackout,” he states.

Drinking water stages have not too long ago been higher on the Paraná and Uruguay rivers, the place Yacyreta Dam and Salto Grande Dam are situated, respectively. As a end result, these facilities were being making shut to their greatest output early on Sunday morning, even though nationwide desire was small. In the meantime, Argentina was also importing about 1,000 megawatts of energy from Brazil via Garabi, a higher-voltage, direct-recent link. With 1 major transmission line down for provider, higher stages of energy were being staying transferred south on the remaining traces from Argentina’s northeast region on the morning of the blackouts.

Santiago Barbero, an electrical engineer at the Nationwide University of La Plata, states Argentina’s grid has automated techniques in position to drop load or technology to match recent desire, which should have isolated any troubles involved with a small circuit and prevented all those problems from spreading during the system. “It is at the moment beneath investigation why these mechanisms did not isolate the event that led to the overall blackout of the Argentinean electrical system,” he mentioned.

A person such system is an automated system termed the Era Computerized Disconnection (identified by the acronym DAG for its Spanish name) that can automatically disconnect generators in two hundred milliseconds if it detects a dilemma. It’s also able of reducing the fee at which energy is fed into the grid. It is unclear what role, if any, this system performed in the blackouts. The DAG consists of a grasp station at a solution place within just the SADI community and various programmable logic controllers situated at substations during the grid.

A advisor for electrical energy techniques in Buenos Aires, who wished to continue to be nameless mainly because they were being not approved to converse on the make a difference, speculated on a possible chain of events that may have prompted Sunday’s blackout:   

“In operational problems like this, against a line tripping in this corridor, the DAG plan carries out technology disconnection to retain the transient security of the Northeast. For this reason, I assume that at first, a single contingency occurred (or double contingency, I really don’t know nevertheless) and the involved DAG plan created a fast first-technology disconnection in Yacyretá (it could have been 6 or seven machines) the energetic energy circulation via the HVDC link should also have been lowered in the kind of a ramp. The adjustment of these distinctive safety strategies is generally examined applying off-line simulations—typically with bigger desire and reasonably normal dispatches (outdoors Northeast location). Dynamic on the net contingency investigation is not performed.

I suppose that for this certain working issue, the amount of money of technology disconnection was insufficient to retain transient security, and then transient instability of generators in the Northeast occurred. Probably, the machines in Yacyretá and Salto Grande that were being in provider were being tripped by some safety. Then some small-term equilibrium level (with regard to the transient security) could have been arrived at, and then the dilemma of frequency security started.

Soon after the disconnection of the Northeast generators, the entire system was left with a huge technology deficit, and the beneath-frequency load shedding strategies (which should drop up to 40 p.c of the desire supposedly, nevertheless it is continue to not identified if they acted perfectly) were insufficient to re-set up the suitable frequency. [The moment the system starts off to disconnect] generators—among them the Embalse Nuclear Electricity Plant, which was the greatest generator in service—[as a countermeasure to] beneath-frequency, the system collapses.”