Cuba's national grid collapses, leaving most of Havana without power

Cuba's National Electric System (SEN) suffered its eighth total disconnection of the year on Friday afternoon, shortly before 2pm local time. The failure began with the sequential tripping of two high-voltage transmission lines running from Matanzas, first the 220 kV Matanzas-Cienfuegos line and then the Matanzas-Santa Clara line, amid unstable weather conditions. This split the grid into western and eastern blocks before a total shutdown followed moments later, with disconnection confirmed from Pinar del Rio to Matanzas at 1:52pm and from Matanzas to Guantanamo five minutes later. By Friday evening only four of Havana's 26 substations and 10 of its 286 distribution circuits were operational, leaving 30,277 of the 862,732 customers served by Havana's Electric Company with power, about 3 percent. Restoration was reported as gradual with no timeline given, and some customers were expected to remain without power even after their circuit was restored, for reasons unrelated to the general disconnection.

Before the collapse, available generation of 1,113 MW fell far short of a projected demand of 3,210 MW, with a maximum forecast impact of 2,007 MW. The official explanation attributed the collapse to the sequential shutdown of two high-voltage transmission lines originating in Matanzas amid unstable weather conditions.

1. Transmission networks with limited redundancy are vulnerable to cascading, system-wide failures when a small number of key high-voltage lines trip in succession.
2. Chronic generation shortfalls relative to demand reduce the margin available to absorb transmission faults and can increase the severity of a full grid collapse.
3. Repeated national disconnections point to the value of clear public restoration information and of investment in line resilience and substation redundancy.

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