Grid collapse triggered by multiple transmission lines tripping - NISO

The Nigerian Independent System Operator (NISO) saysFriday’s national grid collapse was caused by a system-wide disturbancetriggered by the tripping of multiple 330kV transmission lines and thedisconnection of some generating units. NISO data showed load allocation to 11 electricitydistribution companies dropped to zero megawatts (MW) at 1 pm, marking thefirst grid collapse of 2026. In a statement following the incident, the operator saidpower generation dropped to zero MW at about 12:40 pm, resulting in a totaloutage across the interconnected network. “Preliminary operational reports indicate that thedisturbance was associated with the simultaneous tripping of multiple 330kVtransmission lines, alongside the disconnection of some grid-connectedgenerating units,” the operator said. “These events collectively contributed to the systemcollapse at the time indicated.” The operator said power restoration is underway, withelectricity supply already restored to key cities, including Abuja and Lagos,following the grid collapse. “Following the outage, system restoration activitiescommenced at about 13:15 hours, in accordance with established grid restorationand recovery procedures,” NISO said. “As of the time of this update, electricity supply has beensuccessfully restored to Abuja, Osogbo, Benin, Onitsha, Sakete, Jebba, Kainji,Shiroro, and parts of Lagos, while restoration efforts are continuingprogressively in other parts of the country.” NISO added that a detailed investigation into the causes ofthe grid collapse is ongoing, with full restoration and stabilisation of thegrid remaining a top priority.

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