By Sebastine Obasi
Power supply to distribution companies, DISCOs, witnessed a reduction of 16,045 megawatts, MW, in May, according to the daily operational report of the Nigerian Electricity System Operation, NESO, obtained by Vanguard Sweetcrude.
The report shows that 82,147MW were supplied in the month of May, as against 98,192MW supplied in April.
The shortfall was attributed to system breakdown, gas and water constraints.
In May, Sapele I was shut down due to mechanical problems, Omotosho I and II were shut down due to gas constraints, while Odukpani GT1, 2 & 5 was shut down due to the tripping of Ikot-Ekpene/Ugwuaji 330kV line 3 at both ends.
There were also significant line and high frequency constraints at Jebba, Afam VI, Geregu I and II, and Delta leading to generation reductions.
Within the period, system frequency suddenly and sharply dropped from 51.06Hz to 43.37Hz leading to system collapse.
Prior to collapse, Benin/Egbin 330kV line was out on fault due to cut sky wire between towers. Ibom power plant was out due to the tripping of Aba/Itu 132kV line, while Egbin reported higher gas constraints than before, causing further generation reduction.
In April, though supply was higher, there was heavy rainfall reported from Onitsha T/S, Benin T/S and Alaoji T/S, which led to area load reduction from 70MW to 15MW, 100MW to 20MW and 300MW to 51MW respectively.
These led to rise in system frequency and voltage which subsequently resulted in the transmission line trippings.
System Collapse was also recorded in the early hours of 26th April 2017, as system frequency dropped sharply from 50.91Hz to 47.52Hz.
Outages on Alaoji/Ikot-Ekpene 330kV lines 1 and 2, Ikot-Ekpene T/S and Onitsha/Alaoji 330kV line meant that Afam VI and Alaoji National Integrated Power Projects, NIPP were unable to evacuate to the grid, negatively impacting grid stability.
Within the period, despite improvement in gas supply due to pipeline availability, gas constraints continue to be reported as increasing.
Egbin was said to have lost functionality in one turbine due to gas constraints, same thing as Olorunsogo 1 and Alaoji NIPP.
However, Jebba was reported to have lost functionality in one turbine due to water management constraints. Odukpani reportedly lost one turbine to mechanical problems.
Shiroro lost turbine functionality due to high frequency, while Omoku lost turbines due to loss of supply from Port Harcourt mains.
Sapele I ST2 lost functionality as it tripped off due to vibration trouble. Geregu I lost turbine functionality due to high frequency issues, while Okpai lost functionality in one turbine due to an undisclosed fault.
Also, Omotosho I lost functionality in a turbine due to a fire at the station, while Jebba lost functionality in a turbine due to line constraints.