Operator blames transmission faults and network constraints, says reduced supply was not caused by generation shortage…….
The Nigerian Independent System Operator (NISO) has attributed recent reductions in electricity allocations to Lagos, Abuja and parts of northern Nigeria to transmission faults and network constraints, rather than a shortage of power generation.
The operator said multiple transmission line outages had reduced the amount of electricity that could be safely moved to the affected areas, forcing temporary adjustments to allocations to distribution companies (DisCos).
The clarification followed changes in electricity allocations to the Eko Electricity Distribution Company (EKEDC), Ikeja Electric and DisCos serving Abuja and several northern states.
NISO, in a statement issued on Sunday, explained that the amount of electricity generated does not necessarily determine how much power can ultimately reach a particular location.
“The changes in allocations occurred due to multiple transmission line outages that affected available transmission capacity and configuration of the network at different times,” the operator said.
“Adjustments were made in the course of normal system operations to ensure that the interconnected network remained within secure operating limits.
“The availability of generation does not, by itself, guarantee that the available power can be delivered to a particular load centre.
“Power transfer is dependent on the availability and capacity of transmission infrastructure and the prevailing configuration of the network.”
According to NISO, Lagos experienced a reduction in available transmission capacity following outages affecting several key lines supplying the state.
The affected infrastructure included the Olorunsogo-Ayede 330kV Line 1, Benin-Egbin 330kV Line 1 and Benin-Omotosho 330kV Line 1.
The Osogbo-Ikeja West circuit was also unavailable for an extended period.
NISO said the combined outages constrained the amount of electricity that could be transmitted into Lagos without compromising the stability of the network.
It subsequently reviewed and curtailed allocations to EKEDC, Ikeja Electric and the Sakete international supply.
The operator said the adjustments were necessary to keep electricity flows within safe operating limits while the affected transmission infrastructure remained unavailable.
The situation was also more pronounced along the northern transmission corridor, where several outages affected the amount of electricity available to Abuja, Jos, Kano, Kaduna, Yola and other areas.
NISO said the Shiroro-Mararaba 330kV Line 1 tripped between August 24 and 26, leaving the remaining transmission circuit to carry the load and consequently affecting allocations to Abuja and northern parts of the country.
The constraints worsened at 6:47 a.m. on August 27 when the Shiroro-Mando 330kV Line 2 and Mando-Jos 330kV Line 1 tripped simultaneously.
With those outages, NISO said the Mando-Jos Line 1 became the only available transmission circuit serving Jos and the north-east.
The alternative Apir-Lafia 330kV Lines 1 and 2 were already out of service for an extended period because of faults.
The combination of the outages significantly reduced the amount of electricity that could be transmitted to Jos and the north-east.
NISO said the separation of the bus at the Mando transmission substation further altered the network configuration and placed additional restrictions on power transfers to the affected areas.
The operator consequently revised and curtailed allocations to Kano, Kaduna, Jos, Yola and other northern locations.
The Abuja axis experienced a separate transmission constraint on August 29.
NISO said the Shiroro-Katampe 330kV Line 1 and Gwagwalada-Katampe 330kV Line 1 tripped simultaneously at 3:55 a.m., temporarily reducing transmission capacity into the Abuja area.
The two circuits were restored later that morning, with the Shiroro-Katampe line returning at 7:25 a.m. and the Gwagwalada-Katampe line at 7:20 a.m.
Following the restoration, NISO said transmission capacity to the Abuja axis was recovered.
The operator said it continuously monitors the national grid and adjusts generation dispatch and electricity allocations to DisCos according to available transmission capacity and prevailing network conditions.
It explained that when a transmission fault limits the amount of electricity that can be safely transferred, the system operator may redistribute generation, reduce load or revise allocations to distribution companies.
According to NISO, these interventions are part of routine grid management and are intended to prevent localised transmission problems from triggering wider disturbances across the interconnected national network.
“Where a transmission fault limits the amount of power that can be safely moved, the system operator may redistribute generation, reduce load or revise allocations to DisCos,” the operator said.
NISO therefore urged stakeholders to view the recent changes in electricity allocations within the context of the transmission constraints and network configurations that existed at the time.
The operator stressed that the reduced allocations to Lagos, Abuja and northern locations should not be interpreted as evidence of insufficient electricity generation, but as the result of limitations in the infrastructure available to move generated power to those load centres.
