Finding Solution to Perennial System Collapse
Nigeria experienced two major failures in its electricity supply system within 16 hours last week, plunging the whole country into darkness, and exposing serious system susceptibility to shocks. Chineme Okafor reports
The latest incidents have exposed the continued vulnerability of the country’s power system to shocks. Thus, beyond fixing the recent system failures, Nigeria would need to take conscious steps to overcome the challenge of disruptive shocks on its electricity supply system to optimise the benefits of on-going power generations efforts
On Wednesday, January 3, the nationwide blackout that was first witnessed the day before continued following a second system collapse on a transmission line at 14.19 hours. The blackout started with the shutdown of some major gas power generation plants after a section of the Escravos Lagos Pipeline System was reportedly burnt by a raging bush fire. It defied attempts by the Transmission Company of Nigeria to restore the system to normalcy using other generation sources.
System collapses or voltage collapse includes a series of events that results in voltage instability and which could eventually lead to a blackout or an unusually low voltage level in power system. They can be from both technical and non-technical issues.
Shutdown
So, when the national grid collapsed on Tuesday night on account of the fire incident which was reported by the Nigerian Gas Processing and Transportation Company Limited on an axis of the ELPS, about five power plants were shut down because gas supplies to them were cut off and they couldn’t generate electricity. The plants were the 1,320MW-capacity Egbin power station in Lagos; 676MW-capacity Olorunsogo NIPP station; 338MW-capacity Olorunsogo I power station; 450MW-capacity Omotosho NIPP station; and the 338MW-capacity Omotosho I station.
Collectively, they have an installed generation capacity of 3,122MW, but were not exactly generating that much at the time of the fire outbreak, which reportedly spread from Abakila in Ondo State.
However, their shutdown was heavy enough to interrupt the productivity of the grid because Nigeria’s power grid is interconnected and would often experience shocks from such developments at various ends, either in terms of technical or non-technical faults.
Shortly after the first collapse, TCN sent out another notice of a second system failure. It said this occurred when the Odukpani-Ikot Ekpene 330kV transmission line tripped, cutting off electricity generation and transmission from the Odukpani power station to the grid.
TCN, in a statement by its General Manager, Public Affairs, Mrs. Ndidi Mbah, however, assured Nigerians that restoration of the grid had reached an advanced stage, and that it had commenced investigations to determine the exact cause of the system disturbance. It said,“The system disturbance happened at a time when work on the Western Gas Pipeline (Ecscavos-Lagos Pipeline System) by the Nigerian Gas Processing and Transportation Company Limited, which caused a system collapse at about 21.17 hours on Tuesday, was yet to be completed. The grid would have withstood the Odukpani infraction, if generation along Lagos region was available.”
TCN also explained that the NGPTC, the gas supply and marketing subsidiary of the Nigerian National Petroleum Corporation, had indicated that a contractor had been mobilised to repair the affected segment of the Escravos-Lagos pipeline, so that gas supply to the Omotosho, Egbin, and Olorunsogo I and II thermal power stations could be restored.
“According to NGC, work would be carried out day and night and is expected to be completed within 24 hours,”TCN assured in the statement.
Perennial Issue
Considering Nigeria’s challenges with a vulnerable electricity grid, the two collapses served as reminders that the grid was still unstable and this needs the continuous reinforcement TCN said it had embarked on.
Just like it was in 2017, when data from the National Control Centre, Osogbo, showed that a partial system collapse was recorded on January 12 about 8.41am, and which resulted to loss of power supply to Lagos, Osogbo, Jebba, Kainji and Shiroro, and another on January 15, following tripping of the Ugwuaji/Makurdi 330kV line 1 at the Ugwuaji transmission station, the collapse of January 2 and 3, were reflective of the past issues Nigeria’s power system had contended with.
As at the end of 2016, data from the sector’s statistics website, nesistats.org, indicated that 11 total and two partial system collapses were recorded within that year. Similarly, the TCN, according to a second quarter 2017 report from the Nigerian Electricity Regulatory Commission, which was released in September, recorded 15 system collapses. In the report, the TCN recorded five system collapses in the first quarter of 2017 and 10 system collapses in the second quarter of 2017, with the first five been total collapses of the transmission grid, while eight out of the 10 system collapses in the second quarter were total collapses and two partial collapses.
Cause
Though, system collapses could originate from several causes, the obvious cause in the case of Nigeria has been the frequent loss of generation capacity and instability in the transmission network. The frequent trip of power plants from gas supply shortages cause a mismatch between production and load transmission. This puts a strain on other generators, resulting in under-frequency in the system.
Another example is an overload of the transmission system caused by congestion, which forces an overloaded power line to trip and result in increased loading of other lines and additional trips, which in the end result in total collapse due to the high impedance in the weakened grid.
To address this, TCN stated in its statement that it had the support of the Ministries of Power and Finance, and had embarked on the implementation of a Transmission Rehabilitation and Expansion Programme aimed at expanding, rehabilitating and stabilising the national grid. It appealed to Nigerians to be patient with it on this.
Findings
THISDAY gathered that the affected stations were generating about 1,200MW at the time of the fire incident, and that before the Tuesday incident, a peak generation of 4,685.3MW was recorded and wheeled out to the grid on Monday, while the lowest generation on the same day was 3,667.5MW.
According to records, at 06:00 hours on Tuesday, a total of 3,749.90MW was generated and transmitted to the grid for distribution to the 11 distribution companies, while efforts by TCN to sustain minimal supply after the closure of the Escravos pipeline, using generation from the hydroelectric power stations and other gas-fired plants located outside of the South-west, failed at exactly 14.19 hours on Wednesday, when the country was plunged into total darkness.
According to a TCN source, officials of the company worked hard to restore the system with generation from the hydro stations and other plants, but the efforts failed.
NNPC‘s Response
The Group Managing Director of the NNPC, which owns and operates the ELPS, Dr. Maikanti Baru, reportedly ordered an immediate assessment of the damage caused by the fire in order to effect necessary repairs. Baru’s instructions were contained in a statement by the Group General Manager, Public Affairs of NNPC, Mr. Ndu Ughamadu. That statement noted that the affected pipeline also feeds the West Africa Gas Pipeline System.
“The incineration of the ELPS, which was built in 1989, was suspected to have been caused by a bush fire on January 2, 2018 at Abakila in Ondo State,” the statement said.
NNPC added that its firemen were drafted to the scene and were able to contain the fire from the point of leakage on the pipeline, stating, however, that the fire could not be extinguished due to the high pressure on the line. It said,“To put out the fire, the line would need to be isolated and depressurised, which might lead to the complete shutdown of the pipeline segment for repair works to be carried out.
“The exercise will affect gas supply to customers in Ondo, Ogun and Lagos states, with subsequent shutdown of the following power plants with a combined generating capacity of 1,143MW: Egbin, Lagos, Olorunshogo, PEL Olorunshogo, Ogun, Paras Power Plant, Ogun and Omotosho plant, Ondo State.”
The latest incidents have exposed the continued vulnerability of the country’s power system to shocks. Thus, beyond fixing the recent system failures, Nigeria would need to take conscious steps to overcome the challenge of disruptive shocks on its electricity supply system to optimise the benefits of on-going power generations efforts.