Grid of straws

They call it the national grid, and it ostensibly comprises a network of steel towers and high tension lines wheeling electricity from generating companies (GenCos) to distribution companies (DisCos) for onward delivery to end-users. But it could well have been a grid of straws, considering the spate of operational collapses that shut down power supply on the grid and leave swathes of this country in darkness. There were at least two collapses within a span of seven days in recent weeks that left government scrambling for explanation and remediation.

Power Minister Adebayo Adelabu summoned an emergency meeting of managers of the sector – the Nigerian Electricity Regulatory Commission (NERC) and the Transmission Company of Nigeria (TCN) – to trouble-shoot frequent disruptions of the grid. He also raised a panel to unearth the root causes. A statement by spokesperson Bolaji Tunji said the minister was worried that the disruptions could rubbish improvements made over the past year that has led to increased generation and distribution of over 5,500megawatts – a record level of generation in three years. The statement made known that a six-member forensic panel raised by Adelabu was mandated to advise government on “necessary solutions to make the national grid robust and reliable, in addition to ongoing efforts of the government like the Presidential Power Initiatives (PPI) and the Nigeria Electricity Transmission Project (NETAP).” It is also to, among others, “holistically review the national grid stability and identify investments and technical capacities required to make the grid smart and resilient.” The panel is expected to submit its report by  1st November.

Against the backdrop of reports that three collapses occurred within a week, the minister explained that there were “more of grid disturbances than collapses” and just twice. According to him, there was a partial collapse on Monday, 14th October, due to the tripping of a line at the Jebba transmission sub-station and recurring fault at the Osogbo transmission sub-station. Efforts to restore, he explained, encountered a setback the following day that was widely speculated to be another collapse; but the system was fully restored by Wednesday, 16th October. He further said what was reported to be a grid collapse on Saturday, 19th October, was a deliberate protective shutdown of the grid following an explosion of the Jebba transformer, noting that power was restored within two hours.

In its own narrative, TCN gave a more clinical detail of node points of the disruptions and efforts made towards recovery. Also, on a national television programme, TCN Managing Director and Chief Executive Officer Sule Abdulaziz blamed the frequent grid disturbances on aged infrastructure: “The transmission system needs a lot of investment and for so many years in this country, that sector has been neglected. Most of the equipment we use are 50 years or 40 years (old), so it is not possible for those infrastructure to work perfectly.” What is needed to redress blackouts from grid failures, according to him, is a back-up system to which power can be transferred in the event that the main grid stops working. “Presently, we are working on a scatter system for the whole network and it is funded by the World Bank; and the project will take two years to be completed, but now, we have done 70 percent of the project,” he said, adding: “Once we have the scatter system, it will reduce the frequency of system disturbances.”

The TCN boss also made known that efforts were underway to upgrade the transmission lines. He noted, however, that government might not have all the money needed, and so TCN is exploring partnering with private companies to get the funds. “The honourable minister (of power) is now working with the Presidency to have that approval. This is what we call the super grid. By the time we have it, even if there is a fault on one transmission line, you can switch to another one so that we have an alternative. But now, the type of grid we have, once we have a problem with the line, you have no other line to switch to,” Abdulaziz said.

“It is reassuring that the power minister is concerned about grid failures and has raised a panel to unearth the root causes. But it isn’t as if those causes are a mystery right now.”

It helps to understand how the grid works to appreciate the challenge hobbling the present system. The explanation is, of course, highly technical and detailed, but we’ll make it pedestrian here for easy understanding and summarise in view of available space. Here goes: Besides the steel towers and high tension lines, the grid integrates generating stations that load-on the power to be wheeled by TCN and distribution firms that off-take that power for delivery to end-users. But it is designed to operate within a ‘stability’ range determined by voltage and frequency of power on the wheeling lines. Whenever that range is breached, the grid’s operation becomes unstable and it may trip off. The tripping off is not necessarily a bad thing. It could be protective, just the way a circuit breaker functions by cutting off supply when the balance of a domestic electricity system is hazarded.

Grid failure could occur, for instance, when generating firms load onto the system power that is not wheeled by TCN owing to damaged or vandalised infrastructure, or when there is load rejection by DisCos. It could also occur when the distribution firms make demand in excess of available power without the system operator moderating timely by making the DisCos to load shed. It’s like when you load a 2Hp air conditioner and a refrigerator on an ‘I pass my neighbour’ generating set, and the circuit breaker shuts the generator down to protect the house wiring system. TCN shares power to distribution companies based on demand data provided by the National Control Centre. This process aims at balancing power supply with the demand volume; and where power supplied to the grid is insufficient to meet the demand, load shedding is triggered. Where load shedding is not timely synchronised with the power supply level, generators could begin to shut down, leading to grid failure. There are times when the system operator may deliberately shut down parts of the grid for protective or security purposes.

The point must be made that it is typically a sudden and major – not minor – breach in the grid stability range that leaves the system operator backfooted and unable to swiftly restabilise the network, thus leading to a collapse. One way of getting a handle on such exigency is by the use of Supervisory Control and Data Acquisition (SCADA) facility that could make it possible for the system operator to react faster and avert grid collapse. When the Senate Committee on Power was at TCN headquarters on an oversight visit last April, the transmission firm made clear it did not have the SCADA facility and spinning reserve to control the transmission of electricity supply. It is unlikely it has acquired the facility since that time.

Speaking during the senators’ visit, TCN’s Executive Director on Independent System Operator, Engr Nafisatu Asabe Ali, explained: “We have one grid and several participants on that grid. Anybody who misbehaves can bring down the grid. For instance, if any load is introduced on the system without prior knowledge of players, it will bring down the whole system; and since we don’t have a SCADA system, it is difficult for us to know who started it or monitor the flow of the power.” She noted, though, that there were non-mechanistic ways of stabilising the grid, like when there was no record of grid collapse for more than one year – for 421 days. “And what did we do? We introduced an under-frequency load shedding scheme to help us limit this imbalance because that is what the system operator does for 24 hours, and it does not go to sleep, otherwise there will be a problem,” she stated.

It is reassuring that the power minister is concerned about grid failures and has raised a panel to unearth the root causes. But it isn’t as if those causes are a mystery right now. The present grid is too centralised and there is need for a back-up system that can be switched to whenever the main grid has issues; and it helps if the back-up system is by design decentralised into mini-grids. Besides, it should be easier to secure mini-grid infrastructure against vandalisation, unlike the sprawling and for most parts remotely located infrastructure of the main grid. Meanwhile, there is need for massive investment in modernising the present grid and equipping TCN with needed tools like the SCADA system. Government may not have all the money needed, but it can enlist private sector operators and multilateral donors towards upgrading the transmission network. 

Things to be done seem fairly obvious. The question is whether there is political will to do them.