From David Onuoja, Abuja
The Nigerian Independent System Operator (NISO), has attributed the recent reductions in electricity allocations to Distribution Companies in Lagos, Abuja and the Northern corridor, to multiple transmission line outages, and not as a result of generation shortage.
In a clarification statement issued in Abuja on Sunday, NISO said the adjustments were made during normal system operations to keep the national grid within secure limits after several critical 330kV lines went down at different times.
It stressed that available generation alone does not guarantee delivery, as power transfer depends on the state of transmission infrastructure and network configuration.
The Lagos axis it said, was among the worst hit. According to NISO, successive outages of the Olorunsogo–Ayede 330kV Line 1, Benin–Egbin 330kV Line 1 and Benin–Omotosho 330kV Line 1, combined with the prolonged outage of the Osogbo–Ikeja West circuit, significantly reduced transfer capability into Lagos. As a result, load allocations to Eko Electricity Distribution Company, Ikeja Electric and the Sakete international supply were curtailed in line with system-security requirements.
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In the Northern region, the problems began with the tripping of Shiroro–Mararaba 330kV Line 1 between August 24 and 26, forcing supply to Abuja and other northern areas through a single remaining circuit. The situation was worsened at 6:47am on August 27 when Shiroro–Mando 330kV Line 2 and Mando–Jos 330kV Line 1 tripped simultaneously.
With Mando–Jos Line 1 being the only circuit serving Jos and the North-East, and the alternative Apir–Lafia 330kV Lines 1 and 2 already out due to faults, NISO said it had to revise allocations to Kano, Kaduna, Jos, Yola and other areas to protect the remaining network. The separation of the bus at Mando Transmission Substation further constrained power transfer.
Abuja also experienced a brief disruption at about 3:55am on August 29, where Shiroro–Katampe 330kV Line 1 and Gwagwalada–Katampe 330kV Line 1 tripped at the same time, temporarily limiting supply to the Federal Capital Territory. NISO added that both lines were restored later that morning, at 7:20am and 7:25am respectively, after which transmission capacity to the Abuja axis was recovered.
The operator further explained that the incidents highlight the interconnected nature of Nigeria’s power system, where the loss of a single critical line can affect load centres far from the point of outage. It noted that where transmission constraints exist, it must temporarily re-dispatch generation, curtail load or revise DisCo allocations to prevent wider disturbances.
NISO, which is responsible for real-time monitoring, coordination and dispatch of the Nigerian Electricity Supply Industry, said the clarification was issued to set the record straight. “The recent changes in power allocations resulted directly from transmission line outages and the prevailing network configuration, rather than from any shortfall in generation availability”, it declared.
