Evaluation of Daily Load Variability and Harmonic Distortion in the Sub-Distribution Network of a Nigerian University

In Nigerian universities, power supply and consumption fluctuate due to varying daily activities and demand, with electrical harmonics complicating energy management. Despite their importance, there is limited research on daily harmonic behaviour in university electricity usage, making optimizing energy distribution and improving power quality challenging. This study focused on harmonic analysis in the sub-distribution networks of a Nigerian university, specifically examining 19 units of 11/0.415 kV transformers in the FUTA network. Using NEPLAN software, the study assessed Voltage Total Harmonic Distortion (THDv) at points of common coupling (PCCs) under various load conditions, classifying the PCCs into residential, commercial 1, commercial 2, and special types. The results revealed that residential PCCs had a minimum THD of 4.03 in the morning, with a peak ranging from 14.08 to 20.45 between 1 and 5 am. Commercial 1 PCCs had a minimum THD between 3.01 and 10.09 during the day and a maximum THD from 46.66 to 57.02 at night. Commercial 2 PCCs showed minimum THD between 2.09 and 36.04 during the day, with peaks of 8.48 to 65.14 at night. Special PCCs showed minimum THD between 1.2 and 12.80 during the day, with peaks between 14.41 and 20.34 at night. The study found a strong correlation between load variation and harmonic generation, showing that more diverse, non-linear loads result in lower THDv, and harmonic distortion is higher at night across all PCC types.