What causes power system collapses, as two occur back to back Thursday?

What causes power system collapses is the recurring question after two back to back collapses on Thursday left most parts of the country in darkness, some into early morning of Friday?
There have been no reliable and scientifically conducted computations as to losses in Naira terms, but such losses are said to run into billions of Naira.
The history of system collapses are as old as anyone cares to recall, but it has been a recurring decimal since democracy was restored two decades ago.
Every administration posts excuses for the inability to contain the headaches in the power sector, often heaping blames on previous administrations.
Many who can afford it have resorted to self-help, fattening the purses of alternative power supply providers and generator sellers.
Nigeria Everyday reports it is the 14th within a year that the National Electricity Transmission System, will suffer total collapse.
Usually, when a system collapse occurs it takes awhile to get the fragile system back up as it has to take a gradual process to avoid damage or another collapse.
About 67 days ago, according to watchers, a total power grid shutdown forced distribution companies across the country into power load shedding.
The National Electricity Transmission System is being managed by government-owned Transmission Company of Nigeria (TCN).
Media reports say the transmission system has continued to suffer system collapse over the years amid lack of spinning reserve that is meant to forestall such occurrences.
One of the nation’s distribution companies, Eko Electricity Distribution Plc., confirmed the collapse, informing residents of estates on its network that the prolonged power outage, which they suffered yesterday, was caused by the collapse.
Stating that efforts were being made by EKEDC engineers to rectify this and restore power to the estates, the utility company informed residents that the prolonged power outage being experienced was as a result of system collapse from the national grid.
This is not the first time that the company has issued apology to residents over collapse.
On November 9, EKEDC stated that the grid collapsed at 11:15p.m. on Friday and 3:15 a.m. on Saturday. It was experienced across all transmission stations at 23:15hrs on the day.
“Supply was received at 03:15hrs. Sadly, at 04:38hrs, the system collapsed again. TCN and our team are working to restore supply. Kindly bear with us,” the Disco said on its Twitter handle.
Another Disco, Jos Electricity Distribution Plc., announced to its customers that “there is power outage in all our franchise states due to system collapse nationwide.
“We will provide an update shortly. Thank you for bearing with us,” it said.
Four months ago, the power grid suffered a major collapse, the ninth in 2019.
The nation’s power grid, it would be recalled, also recorded its eighth total collapse in July, plunging consumers across the country into blackout for some hours.
The government-owned TCN, which manages the grid, blamed electricity distribution companies for the system failure.
The grid suffered four total collapses last year January and one each in February, April and May, according to the system operator.