By Busola Aro

The Nigerian Independent System Operator (NISO) says recent changes in electricity allocations to distribution companies (DisCos) in Lagos, Abuja, and northern Nigeria were caused by transmission line outages and network constraints, rather than a shortage of generation.

The operator spoke in a statement on Sunday, NISO said multiple transmission faults reduced the capacity to move available electricity to the affected areas, forcing it to temporarily cut allocations to DisCos to keep the national grid within safe operating limits.

The clarification comes amid changes in power supply allocations to Eko Electricity Distribution Company (EKEDC), Ikeja Electric Distribution Company (IE) and DisCos serving Abuja and northern states.

NISO said the amount of electricity generated does not automatically determine how much power can be delivered to 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 statement reads.

“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.”

For Lagos, NISO said the state was affected by outages on 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,” the operator said.

According to NISO, the combined outages reduced the amount of electricity that could be safely transmitted into Lagos.

The operator said it consequently reviewed and curtailed allocations to EKEDC, Ikeja Electric, and the Sakete international supply.

“The northern corridor was affected by the tripping of the Shiroro-Mararaba 330kV Line 1 between August 24 and 26,” NISO said.

“The outage affected allocations to Abuja and northern parts of the country because the remaining transmission circuit had to carry the load.

“The situation worsened at 6:47am on August 27 when the Shiroro-Mando 330kV Line 2 and Mando-Jos 330kV Line 1 tripped simultaneously.”

NISO said Mando-Jos Line 1 was then the only available transmission circuit serving Jos and the north-east, while the alternative Apir-Lafia 330kV Lines 1 and 2 had been out of service for an extended period because of faults.

The simultaneous outages significantly reduced transmission supply to Jos and the north-east.

NISO said the separation of the bus at the Mando transmission substation further changed the network configuration and restricted power transfer to the affected areas.

The operator said it subsequently revised and curtailed allocations to Kano, Kaduna, Jos, Yola, and other affected northern locations.

For Abuja axis, NISO said there was a temporary transmission constraint on August 29, noting that the Shiroro-Katampe 330kV line 1 and Gwagwalada-Katampe 330kV line 1 tripped simultaneously at 3:55 am.

According to the operator, the two circuits were restored at 7:25 am and 7:20 am, respectively, after which transmission capacity to the Abuja axis was recovered.

‘ALLOCATIONS REDUCED DUE TO NETWORK CONDITIONS, CAPACITY’

NISO said it continuously monitors the national grid and adjusts generation dispatch and DisCo allocations based on available transmission capacity and network conditions.

“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 statement added.

The operator said such measures are necessary to prevent wider disturbances on the interconnected grid.

NISO said the recent changes in allocations should, therefore, be understood as a consequence of transmission constraints and network configuration at the affected times, rather than a lack of available generation.

Source: TheCable