Substation Load Management for Electric Power Distribution's Sustainability

Abstract

In Nigeria, perhaps due to lack of conscious and planned preventive maintenance culture coupled with inadequate measuring equipment, power system equipment such as transformers are not adequately monitored for preventive maintenance. As a result, most are left to work until a breakdown occurs. Poor loading and uneven distributions are also common phenomena in many of these distribution transformers. Hence, there is a frequent power outage and supply interruption. This paper reports daytime monitoring of voltage, current and apparent power from three transformer substations at Federal Polytechnic Ilaro, Nigeria to ascertain loading and transformer conditions. The work involved data acquisition using Lutron DW 609 power harmonic analyzer of the parameters of interest (voltage, current and apparent power) for 2-4 hours using 5 min logging interval. The data were assessed using the computer system for analysis. The range of loading conditions encountered was: Substation 1: 75.00−80.60 kVA which was 15−16.14% of transformer rating; Substation 2: 73.70−90.30 kVA representing 14.74−18.08% of the transformer rating; Substation 3: 19.04−19.28 kVA representing 3.81−3.85% of the rated transformer capacity. Load factors of 0.97, 0.87, and 0.99 were obtained for the three substations respectively indicating that energy usage was relatively constant during the period under consideration. An ANOVA test at a 5% significant level on each transformer phase current reading yielded F-Values of 4475.38, 859.92 and 239117.68 respectively for the substation transformers indicating a huge level of imbalance in the transformer loading. Load balancing is recommended for a sustainable electric power distribution in the locality.