Frequent collapses of Nigeria’s national power grid have become a recurring nightmare for residents and businesses.
Within a week, the country experienced a series of power outages, leaving millions without power for extended periods.
power grid
A power grid is a network of transmission lines that connect multiple power plants to loads spread over a large area.
Power plants, transmission lines and towers, and individual consumer distribution lines make up the power grid.
It is intended to operate within certain limits, known as stability limits, according to voltage, current, and frequency.
As a result, when these limits are outside the stability range, the grid behavior becomes unstable and may collapse.
Related article: Power grid collapse plunges Nigerians into darkness for third time in a week
Reasons for the collapse of the national power grid according to power sector analyst Hab Sadiek
The National Grid is an interconnection of high-power transmission lines/cables across the country.
Grid frequency measures the demand and supply of electricity sent from Genco to consumers.
Frequency meters measure in Hertz (Hz).
Based on the grid code, the normal frequency level is considered to be 50Hz.
example:
If the current electricity generation is 4000MWh and people are using all 4000MWh, then supply should equal demand and the frequency should be 50Hz.
This is a very unlikely perfect situation.
If we generate 4000MWh and people use 3700MWh, the frequency will show up as 51Hz because obviously supply is higher than demand.
If we are generating 4000MWh and people are trying to use 4200MWh, the demand will be higher than the supply, so the frequency will show 49Hz.
You may ask, how are you going to generate 4000MWh and use 4200MWh?
For example, let’s say you have an I-pass-my-neighbor generator and want to connect the generator’s 2HP AC to your microwave.
The generator will stop automatically.
The same thing happens on grids across the country.
Nigeria’s national power grid is set to operate at specified frequency levels
Upper limit = 51.25Hz
Lower limit = 48.75Hz
The SO’s job is to ensure that the frequency movement lies between these two levels.
Significant deviations from these two levels, above or below the threshold, can trigger the collapse of the national grid.
Also read: Power restored in parts of Lagos, Ibadan, national power grid comes online
A grid collapse is different from a collapse where something bad happens. For safety and security reasons, the 26 generators connected to the grid will be automatically shut down.
If a major electrical fault occurs in your home, the circuit breaker will trip and shut off the entire power supply, protecting everyone from potential injury or damage.
Demand for electricity is not static. For example, let’s say you have 10 air conditioners and other appliances in your home.
At full capacity, your home is consuming 500Kwh, and the average capacity could be less than 300Kwh.
In this hot climate, let’s say you only have 250Kwh allocated to your home and are trying to run it to full capacity. If you turn on all the switches, the demand will exceed the available supply and therefore the lights will automatically turn off. off
These are all examples of how demand is going to outstrip supply, and how the system protects itself.
Conversely, if supply exceeds demand, the system will shut down as well for safety reasons.
In Nigeria, supply does not always exceed demand unless something untoward happens. Let me explain.
In 2022, when the TCN Labor Union (NUEE) decided to go on strike, they suddenly went lights out without any notice and without following the normal process, and this caused an imbalance
between demand and supply.
There is no need for the SO to transfer the load anywhere and it will disconnect electricity to the Abuja axis and surrounding areas. As a result, although generators were running, there was no one to pick the load, so supply increased and demand decreased. In other words,
For example, GenCos generates 4000MWh. You decided to shut down almost 500MWh instead of letting that MWh go elsewhere. This becomes redundant and the system will not accept redundancy. Therefore, the entire power plant shuts down to protect itself.
In some cases, frequencies can exceed 52Hz because supply is higher than demand.
Also read: TCN says power grid collapsed due to transformer explosion
This is why we see that they bring light now and remove it again.
Demand is not static and as it changes, the SO ensures that there is enough supply to keep the frequency reading within acceptable limits.
TCN has requested 200Mw from DISCO and plans to reduce that 200Mw to 190Mw in the short term depending on generation and demand trends.
All this is done to protect the grid and maintain balance.
If TCN requires the DISCO to reduce its MW, then the DISCO may cease operations or undergo major repairs.
Also, if a repair is needed and the Disco cannot remove the power supply, the Disco will have to rewire it somewhere else or TCN will do the repair themselves.
The cause of grid collapse is not a small MW imbalance in the generation pool. It must be such a significant disruption that it causes an imbalance within a short period of time and makes it impossible for the SO to respond immediately.
If you have a generation pool of 4000MW, a problem suddenly occurs in the transmission line and almost 500MW is taken out. This is serious enough to cause grid collapse.
Even that 500MW has to be so fast that the SO cannot react instantly.
Disruptions like 10MW, 20MW are less important and are usually handled by SO or Disco.
Another way to maintain the grid without collapsing is to fully and completely use Supervisory Control and Data Acquisition (SCADA).
This makes it easier for the SO to react more quickly and prevent grid collapse.
Spinning reserve is also an option
But we don’t have enough generations without stories of having spinning reserves.
Reserve refers to a situation where demand is increasing and the supply is immediately increased to meet the demand.
When the power grid collapses, the SO immediately orders power plants to be restored or restarted. It is usually called a black start.
They get the power plant up and running and gradually begin to power the strategic discos.
This is a normal process, similar to when a circuit breaker trips and you repair it to get the lights back on.
This is why the power grid collapses and restarts before the news comes out. By the time it becomes news, some people will say, “We have light.”
It should also be mentioned that some power plants are not connected to the grid, leading to partial collapses or complete system collapses. These are also the reasons why someone from a faraway, remote location can claim to have light when the power grid collapses.
