ABSTRACT

Over the years, the Nigerian power system is beset with lingering problems, namely, severe power losses, as well as very low transfer capability of the transmission network to evacuate power from generating stations to the load at the distribution level.Presently, the Nigerian power industry is undergoing restructuring, especially in the generation and distribution systems. In view of the deregulation of electricity distribution and marketing, the traditional practices of the Nigerian power system is undergoing changes so as to address the identified problems in the existing power system. Specifically, better utilisation of the existing power transmission network to improve on the system transfer capability and minimize cost is one of the key focuses of thisdissertation. The dissertation deals with the enhancement of transfer capability of Nigerian 330kV network using Flexible Alternating Current Transmission(FACTS)devices.FACTS devices are used for controlling transmission voltage, power flow, reducing reactive losses, and damping of power system oscillations for high power transfer capability. Three FACTS devices; Thyristor Controlled Series Compensator (TCSC), Unified Power Flow Controller (UPFC) and Interline Power Flow Controller (IPFC) were used to investigate the transfer capability of the Nigerian 58-bus power system network. NEPLAN,Power system analysis toolbox (PSAT) and data collected from National Control Center (NCC) Osogbo were employed in this dissertation to model the Nigerian 58-bus grid system and optimally placed the FACTS devices at the weakest bus that was found out through the computation for available transfer capability (ATC) after continuation power flow (CPF) simulation was completed. From the CPF, it was observed that lines 20(Geregu GS-GereguTS), 33(Omotosho TS-Benin TS), 40(Olorunshogo TS-Ikeja West), 42(Omotosho TS-Ikeja West), 43(Akamba-Ikeja West), 45(OkearoTS- Ikeja West), 58(Benin TS- Onitsha TS), 64(Sapele GS-Sapele TS), 72(Eket TS-Ibom GS) and 82(Afam TS- PH Main TS)  were found to be very weak lines with the following power (MW):211.97, 211.73, 215.75, 213.52, 217.29, 220.57, 218.85, 215.86, 210.01 and 214.85 respectively, and therefore, most suitable for the installation of the FACTS devices.MATLAB codes were developed and used to calculate power transfer capability of the network without and with FACTS devices. The results of transfer capability of the Nigerian 330 kV, 58-bus grid network without FACTS is 407.93MW, with TCSC is 1,115.7MW, UPFC is 7,277.7MW, IPFC is 2,166.9MWand combination of the three FACTS is 3,900.4MW. The average percentage transfer capability obtained by inserting FACTS devices is 82.59%.Comparing the three FACTS devices, the results obtained show that UPFC enhanced the power transfer capability of the network more than TCSC and IPFC.