Estimating Voltage Profiles and Power Margins in an Electric Power Network

Abstract

Nigeria's power system in recent times have experienced tremendous improvement in the network in terms of building of more generating stations, lines etc., however there are still some level of power losses in the network that can actually be effectively
managed. In order to determine the current status of the network, a power flow study using Newton-Raphson (N-R) method was
carried out for the current Nigeria 330kV power network. This network consist of twenty five(25) generating stations with total
installed capacity of 12,870MW and available capacity of 5,180.70MW,Seventy Two (72) Buses and Ninety (90) transmission lines and was modelled and then simulated using ETAP software. The results obtained showed that the total active and reactive power losses were obtained to be 22.2MW and 32.30MVar respectively. Bus voltages below 313.5kV are seen as under voltage (weak) buses, while those above 346.5kV are seen as over voltage buses and the work identified these buses. The weak buses were identified to include Aja (304.68kV--0.922pu), Lokoja (311.152kV-- 0.9429pu), Ayede (11.152kV--0.9429pu), Sakete (297.312kV-0.9009pu), Katamkpe (298.157kV--0.9035pu), Gwagwalada (292.369kV--0.8859pu), B-Kebbi (311.9653kV--0.9454pu), Kano (298.157Kv--0.9035pu), Zaria (292.368kV 0.8859pu), Kano_New (311.965kV--0.9454pu), Funtai (305.961kV--0.9271pu), Gombe (302.820kV--0.9176pu), Damaturu (296.822kV--0.8995pu), Makurdi (290.038kV--0.8789pu), Maiduguri(291.418kV--0.8837pu) and Jalingo (294.151kV--0.8914pu). Load power was also determined for the seventy two buses and their values recorded. Although most single lines have been made double, triple and quadruple and the line lengths have also been reduced as more buses (substations) have been constructed and more installations of reactors and shunt capacitors are all in the current Nigeria 30kV network, there is still need for more improvement in terms of full automation of the network and use of SCADA technology. Upon incorporation of these, losses will be high reduced and the voltage profiles for each of the buses will be within the allowable tolerable limit.