Power generation dropped by 4.65 percent to 3,699.60 Megawatts, yesterday, with most parts of the country going without electricity supply. According to data from the Independent System Operator, ISO, portal, a semi-autonomous unit at the Transmission Company of Nigeria, TCN, the drop was against the peak generation of 3,756.3MW recorded on Saturday, translating to a 49.94 MW loss.
This came as the industry report – Spinning Reserve to do or not to do? NESI Conundrum: Save Our Machines – obtained by Energy Vanguard, blamed the instability on some problems, including unreliable power network.
The report stated: “The grid disturbances primarily hinge around variations between generation and demand leading to frequency excursions. Often these frequency excursions are well outside the Grid Code operational limits of 50Hz ± 0.25Hz, and often exceed the “system stress” limits of ±1.25Hz as shown by the snapshot of Nigerian grid frequency excursions. The Nigerian power system requires a minimum spinning reserve that is enough to cover the largest credible trip to secure the network. This is because the grid operators find it nearly impossible to keep the frequency within the grid code required narrow band.
“Daily, the frequency varies from 51.5 Hz to 48.5 Hz as against Section 15.3.1 of the grid code, which states that the Frequency shall be maintained at 50 Hz. The inability of the system operator to maintain grid stability to acceptable technical limits has exposed generator units to perform beyond factory rated capability. Frequency deviations out of technical tolerable limits are not only damaging to the units but also are increasing both the machines fixed maintenance cost and variable maintenance costs.
“Steel Mills form a large chunk of funds both for the DISCOs and the TCN but detrimental to the generation machines. It is trite that steel mills creates harmonics and causes voltage fluctuations at a very high level. These harmonics creates lots of stress on the rotors of the turbines. They create inverse torques on the blades of the rotors producing cracks and distortions. The GENCOs have been due to this menace saddled with continuously adjusting their AVR. There is too much volatile load mostly brought by steel mills.”
Research shows that close to 50 Steel Mills are connected to the Nigeria electric grid. The load for the Steel Mills varies from 3 to 35 MW, depending on the Steel Mill. Another damning impact on the GENCOs is the accrual of the Equivalent Operating Hours (EOH) before the ascribed time. For instance, where GENCOs are expected to spend about two billion naira on major inspection every four years, due to the efficiencies, the period is shortened to two years.”
The report added: “The foregoing, portend that paying for spinning reserve is just a little way of compensating a generating plant who suffers greatly just to keep the grid running. Also it is a right mandated by the grid code and if we are going by the provisions of the Market rule 1;4, all market participant must adhere to the prevailing marked rules and codes.”