Browsing by Author "Mohammed, O. O"

Now showing 1 - 6 of 6
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    Field Loss Calculation of a Wind-powered Axial Flux Alternator by Analytical Equations.
    (Wiley Online Library, 2021-02) Otuoze, A. O; Mohammed, O. O; Ibrahim, O; Emmanuel, A. A; Usman, A. M; Dobi, A. M
    Various techniques have been investigated and proposed for core loss minimization in electrical machines. Nevertheless, many of such methods are mostly complicated and not suitable for consideration at a preliminary design stage. In this work, a simplified procedure which uses an analytical approach to minimizing the field’s losses of an Axial Flux Permanent Magnet Alternator (AFPMA), is presented. First, the output equation of an AFPMA is referred, and then the minimization of the losses is investigated by analytical differential equations. The result of the derived-specific magnetic loading is investigated using three different core materials, namely 35RM300, 50JN350, and 65JN800, and is found to reduce with increased frequencies. The 35RM300 core material gives the maximum specific magnetic loading and minimum power loss at investigated frequencies of 50 to 500 Hz. Although the 35RM300 core material gives the best performance, the optimal values are only determined as suitable by the manufacturer’s design criteria. This study is a key indicator for a simple and efficient core material selection in the design of a Wind-Powered AFPMA without the need for complicated analyses at the preliminary design stage.
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    Identifying interaction boundary of inverter-based generation in assessing system strength of power grids using relative electrical distance concept
    (Elsevier, 2024) Sanni, S. O; Mohammed, O. O; Abdullateef, A. I; Mohammed, D. S. S; Oricha, J. Y
    The increasing use of inverter-based generation (IBG) in power grids raises concern about system strength. This is partly due to the inherent interactions among multiple IBGs in close proximity to one another. This paper proposes an approach to identifying the existential boundary of interaction in a network using the relative electrical distance (RED) concept. The mathematical formulation of the RED concept to address the interaction problem among the IBGs involved utilising the power system network’s admittance matrix to capture its structural characteristics. An interaction matrix derived from the RED values of all IBG pairs was then developed to identify the interacting IBG groups. The proposed approach was demonstrated using the IEEE 39-bus system and a practical 72-bus Nigerian power grid. Results showed that RED values effectively group interacting IBGs, with values closer to 0 signifying higher interaction levels, values closer to 1 indicating lower interaction, and a value of 1 denoting no interaction. Time-domain simulations confirmed the accuracy of the approach, demonstrating that the effect of control interaction propagates proportionally to neighbouring IBGs based on RED values. However, fault currents can influence the impact of control interactions. This approach, which requires less computational effort, provides a quick identification tool for potential areas of concern based on the degree of interaction, enhancing the reliability of power grids with high IBG penetration.
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    Investigating the impact of solar PV and wind energy systems on the strength of a longitudinal power grid
    (Elsevier, 2024) Sanni, S. O; Abdullateef, A. I; Mohammed, O. O; Aman, M. N; Raji, A. K; Fajuke, I. D
    The integration of inverter-based generation (IBG), such as solar photovoltaic (PV) and wind systems, presents unique challenges for power grid strength, especially in regions with limited conventional generation capacity. This study investigates the impact of such integration on the strength of Nigeria’s power grid, focusing on sparsely connected northern region with abundant renewable resources. Using the network response short-circuit ratio (NRSCR) metric, which accounts for interactions between IBGs, we assess grid strength in three case studies. Simulations were conducted with the Power System Simulation for Engineering (PSS®E) software. Static analysis reveals inherent weakness in the northern region, characterized by low short-circuit capacity. Integrating IBGs at nine strategic locations shows varying responses: strong buses (NRSCR > 10) adapt well, while weak buses (NRSCR < 10), particularly in Kano and Katsina, constrain the operational capacity of the IBGs. Furthermore, close interaction among IBGs at these locations significantly impacts the system’s dynamic response, although planned addition of conventional generators offers marginal improvement. This work highlights the potential of renewable resources to address energy shortages but also underscores the crucial need for detailed design studies at each point of interconnection (PoI), considering the longitudinal grid layout in the northern region and potential limitations imposed by IBG interactions. The findings also offer a structured approach that can be applied to power grids with comparable IBG integration levels, similar to the energy landscape of Nigeria.
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    Replacement Model for Street Lighting Systems
    (Faculty of Engineering, University of Nigeria, Nsukka, Nigeria, 2021-01) Usman, A. M; Adediran, Y. A; Otuoze, A. O; Mohammed, O. O; Zakariyya, O. S
    Replacing failed bulbs of streetlights in a location can be very tasking and expensive if the optimal time for replacement is not determined. In this paper, a model has been developed that helps to establish the optimal time for the replacement of streetlight bulbs. Burnt-out bulbs are replaced individually when they fail, and group replacement is carried out on all bulbs after a specified time. The costs for both individual replacement and group replacement are determined. The developed model was applied to locally sourced data from a field survey of a streetlight installation at the University of Ilorin, Ilorin, North-central Nigeria. The model gave the optimum replacement time of burnt-out bulbs as the eighteenth week when applied to the data used in this work. The optimum replacement time will be dependent on the dataset used. This makes the developed model useful in establishing the optimal replacement time of any stochastically failing items that are in large quantities. The model will help to reduce maintenance costs for facility managers.
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    A Review of Smart Grids Deployment Issues in Developing Countries.
    (Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria., 2017-12) Otuoze, A. O; Usman, A. M.; Mohammed, O. O; Jimoh, A. A
    Smart Grids (SGs) have taken a centre stage in achieving a smarter, more reliable, robust, secured, economically efficient and more environmentally friendly mode of power generation and utilisation. Massive deployment is being recorded in developed worlds. While most of these countries are investing heavily in the development of SGs, well-articulated areas of research and development are key aspects with special emphasis on its security since it involves complex interconnection of units and systems which are expensive to install and maintain. In developing nations, especially those of Africa, realisation of adequate power supply to meeting the ever-growing demand has been a mirage with demand on geometric increase and with every increase largely meaning a drift away from the supply. Hence, attention is focused on capacity expansion in most developing nations rather than SGs deployments especially considering the various challenges militating against the development despite the huge advantages. Although, some of these nations have made tremendous achievements in this regard, the associated challenges have become major source of worry for most of the nations. This paper gives highlights of these issues and possible measures of overcoming them in order to enhance sustainable SGs deployments in developing countries like Nigeria.
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    THE IMPLICATIONS OF LOW SHORT-CIRCUIT CAPACITY ON THE STRENGTH OF POWER GRID: A NIGERIAN CASE STUDY
    (Faculty of Engineering and Technology, 2023) Sanni, S. O; Abdullateef, A. I; Mohammed, O. O
    The quest to integrate renewable energy sources (RES) into power grids arises from the need to adopt a sustainable source of energy while achieving energy security. RES such as solar photovoltaic (PV) and wind energy systems are also called inverter-based generators (IBGs) because of their inverter-interfaced connections with the grid. The inverter's quick dynamic response and low short-circuit capacity (SCC) can cause distress to the grid and potentially result in power system stability problems. This paper has assessed the SCC and system strength of the Nigerian grid based on proposed IBG integrations in the northern part of the country. A shortcircuit study was conducted, system strength was evaluated using the Network Response Short Circuit Ratio (NRSCR), and a dynamic voltage stability analysis was performed. These studies revealed that most of the proposed points on the grid have low SCC but suitable for the size of IBG integration; however, some identified weak points may affect the stability of the grid. The results of this investigation provide valuable insights on the impact of IBG integration in renewable energy-rich, SCC-deficient areas of a grid.