Electrical Engineering-Scholarly Publications

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Browsing Electrical Engineering-Scholarly Publications by Author "Ajekigbe, T.O."

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    Open Access
    Assessment of electrical grid fragility in Nigeria-31 bus system
    (Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria., 2018-12) Oluseyi, P.O.; Ajekigbe, T.O.; Babatunde, O.M.; Akinbulire, T.O.
    The grid fragility is a prevalent challenge in Nigeria electricity supply industry (NESI). It has resulted in recorded incidents of voltage collapse which have been on the increase in the recent time. Meanwhile to evaluate this events; thus the nexus between voltage collapse and network capacity was explored. To actualize this, the load flow analysis was carried out on the Nigeria-31 bus system with the aid of the Newton-Raphson iteration technique. Using the relevant parameters (such as bus voltage magnitude, bus voltage angle, generated power, injected power as well as load magnitude) obtained from the analysis, the line stability index and line stability factor were obtained for every line in the network. It was discovered from the values of line stability index that Lines (26-2); (31-7); (10-11); (24-10) and (18-12) are weak and fragile while for the line stability factor, the values obtained for Lines (10-8); (11-8); (11-10); (24-10) and (18-12) indicate the fragility of some of the lines in the Nigerian Transmission Network. From this, it was established that the weakest lines were those whose values range from 0.3051 to 0.8813 for the line stability index. Correspondingly; any line that takes the value between 0.2737 and 0.9924 in respect of the line stability factor was also marked as the weakest lines in the network. Thus it was noticed that for the two line stability indices (i.e. stability factor and stability index); Line (11-10) i.e. from Oshogbo to Ikeja- West bus is the most fragile line in Nigeria-31 bus transmission network while the nearest to it are lines (24-10) i.e. from Ayede to Ikeja-West bus and (12-18) i.e. from Kaduna to Kano bus. This study is potentially sufficient for determining the lines in the transmission network that require utmost consideration for reinforcement in respect of the transmission expansion planning schemes.
  • Item
    Open Access
    Transmission expansion programme for electric network reinforcement
    (Faculty of Engineering University of Maiduguri, Maiduguri- Nigeria, 2019-03) Oluseyi, P.O.; Ajekigbe, T.O.; Akintunde, T.J.
    Due to the increase in electricity demand, transmission sector has become overstressed since it can only be built at vast cost. In many developing economies, the network is highly susceptible to outages, collapse as well as partial or total failures, since the existing transmission capacity limit is often closely approached. To overcome this challenge better transmission expansion needs to be considered. This paper identified the implementation of transmission expansion with a number of creative approaches for overcoming network collapse in poor economy. The study deployed the application of improved Strength Pareto Evolution Algorithm (SPEA-2) optimization approach for solving the transmission expansion problem based on a simple power flow model. This model was deployed for running the Nigeria- 31-bus system; to serve as the benchmark hence the standard IEEE 30- bus system was also considered. Using the traditional approach, the results obtained from the power flow analysis revealed that there are four major buses that recorded very high severity of violation. These were Jos, Kaduna, Kano and Birnin-Kebbi buses. In furtherance to this, additional effort was made to establish these findings by adapting the contingency analysis tests which provided more information on the earlier results so as to establish that these buses made the adjoining transmission lines connecting them to be identified as weak. Thus this serves as the contributory factor to the violation experienced by the entire the power network. For a more creative vivid display of the results; the Powerworld software was engaged for the analysis of the existing Nigeria-31 bus system while the violated buses that require more energy flow were provided with double circuit. This, thus, resulted in improved power outflow and inflow to the buses which led to the reduction of losses in the network. In conclusion, this study established that the transmission line connecting the geographical northern and southern parts of Nigeria dissipated quantifiably large value of losses which is mainly due to the nature and length of the line linking the source of electricity supply to a number of the load centres in the farther part of the country. Hence, it is suggested that the transmission expansion programme should be adopted for the improvement of power flow quantity which will, on the long run, reduce the power loss suffer by the existing network