TCN says national grid still fragile, gives conditions for stability
“Our grid is still fragile,” the Transmission Company of Nigeria (TCN) has at the weekend stated.
This is following a system collapse witnessed last Wednesday, that resulted in blackouts in some parts of the country.
While briefing newsmen on the development in Abuja, the Company’s Managing Director (MD) Usman Mohammed said the grid was still far from achieving stability.
He said despite the ongoing transmission expansion projects, there was a need to address four key factors before the country can attain the desired grid stability status.
His words: “When we say that we have achieved some level of improvement, it does not mean that we have stabilised the grid and we are disturbance-free, what I am trying to say is that our grid is still fragile, it is a journey that will take us to grid stability.”
According to him, there was a need for critical investment in lines and substations across country saying; “I have always told you that we need to achieve four important things four the grid to be stable and one of these is that we need to have a critical investment in lines and substations so that we will have N-1 supply across the country. It means any equipment that goes out at any point in time should not affect the supply. If you look at what happened in Apo recently where we had a transformer that got burnt and I am sure we restored supply in less than two hours that means we have N-1 in Apo and we are supposed to have that across the country.
“We have invested a lot of money in lines and substations up to $1.6 billion but you know an investment in transmission takes time, it is not like something you can fix in one day. Of course, we are using our staff, cleared stranded containers but we are not yet there because the critical investments from the donors have not yet materialised, the equipment have not yet arrived talkless of installing so we are in a journey.”
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The MD also disclosed the need for a spinning reserve stressing that the country currently has none of such.
Spinning Reserve is the online reserve capacity, synchronised to the grid system and ready to meet electric demand within 10 minutes of a dispatch instruction by the Independent System Operator (ISO).
It is needed to maintain system frequency stability during emergency operating conditions and unforeseen load swings.
Although he said a competitive procurement for the spinning reserve has been completed, the TCN was yet to get approval from the Nigerian Electricity Regulatory Commission (NERC).
“We also need to have Spinning reserve. For an average generation of 4,000MWs, the spinning reserve is supposed to be 10 per cent that is 400 but as we speak we have zero spinning reserves.
“Now we have gone ahead to do competitive procurement for spinning reserve and we have completed the procurement of 260. The 260 is completely inadequate but it is good enough to say we have more stability in our grid. So it is not yet approved by NERC.”
Mohammed further stressed the need for frequency control and a functional SCADA to effectively stabilise the grid.
On his part, Head Transmission Provider, Engr. Victor Adewunmi identified over-voltage occasioned by sudden loadshedding by DisCos as a major cause of system collapse.
He explained that during the rainy period, DisCos often drop-off supply leading to over-voltage which destabilises the grid.
“One of the major causes of instability to the grid now is overvoltage occasioned by the sudden drop of heavy loads from the discos and this cuts across all parts of the country. We are now in the rainy season I can tell you that anytime it rains, a load of about 1000MWs can suddenly reduce to about 200Mws it is not acceptable. What is the resulting effect? It is over-voltage.”
He further explained that: “In the cause, we are describing the voltage from about 330 to above 400kv, no equipment is manufactured to withstand such voltage. The effect is that we had some explosions in Jebba, Shiroro and in Jos and this is one of the things that delayed restoration to Abuja because anytime we have system collapse, we normally restore Abuja through Shiroro.”