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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Akeem Damilola Akinwekomi High-entropy alloys (HEAs) have excellent properties that are being explored for potential applications in many engineering fields. Their excellent properties strongly depend on their phases. The vastness of alloy compositions that can be synthesized makes it extremely challenging to experimentally investigate all the possible HEA types. To mitigate these challenges, more efficient and systematic computational techniques can be applied to the existing experimental data to accelerate HEA design and discovery. Therefore, this study developed three soft computing classification models based on artificial neural network, k-nearest neighbor (kNN), and support vector machine (SVM) to classify solid solution, amorphous and intermetallic phases in HEAs. Empirical studies showed that hyperparameter optimization improved classification accuracies of the classifiers with kNN (92%) outperforming ANN (86%) and SVM (90%) using all five predictive features. Feature selection did not improve the classification accuracy of any of the model. This studied demonstrated the importance of applying soft computing techniques and hyperparameter optimization for enhancing the classification accuracies of models to predict the phases in HEAs.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Augusta Ijeoma Ekpemogu, Taiwo Ebenezer Abioye, Chloe Rose Cunningham, Rotimi Obolo, Abu Seman Anasyida, Tunde Isaac Ogedengbe High strength 7xxx series aluminium alloys are widely utilized in the aerospace, automotive and other manufacturing industries due to their low cost, high specific strength, high stiffness strength and fracture toughness. Additive manufacturing presents new opportunities in producing 7xxx series aluminium alloys such as reduced material waste, shorter lead time, and increased design freedom. This paper reviews the current progress in Wire Arc Additive Manufacturing (WAAM) of 7xxx series aluminium alloys, a technology that offers benefits such as better energy absorption than alternative laser-based processes, high deposition rates, and unrestricted build size. A classification of the AM processes utilized to fabricate aluminium alloys and WAAM process variants for fabricating aluminium alloys are introduced. Also, some common defects including porosity, solidification cracking and volatile elements loss encountered during the WAAM process of 7xxx series aluminium alloys are discussed. Whilst porosity remains a major issue in 7xxx series aluminium alloys produced via WAAM, several opportunities to minimize or eliminate the defects through process selection and alloy development are presented.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Olatunji Oladimeji Ojo, Ayodeji Olumide Oluwale This paper integrated two severe plastic deformation methods, namely frictional extrusion, and friction stir spot welding to obtain synergetic benefits and create a friction extrusion spot welding (FESW) process. The FESW process was carried out with the use of AA1xxx Al alloy by interchanging the location of the predrilled extrusion hole (between the upper and bottom plates). The microstructure, tensile-shear load, and fracture behaviours of the welds were investigated. The results revealed the presence of no weld discontinuities/flow-aided defects while the FESW process was effective in filling the extrusion holes irrespective of the location of the predrilled holes. An inverse relationship was found to ensue between the tool’s rotating speed and the tensile-shear load of the bottom plate hole-friction extrusion spot welded joint joints while a direct correlation occurred between the tensile-shear load and the rotational speed (up to 1100 rpm) in the top plate hole-friction extrusion spot welded joints. The difference in the tensile and fracture behaviours of the two weld categories is attributed to the disparity in the hole-filling mechanisms. The maximum tensile shear load of 3.1 kN (at 710 rpm) and 3.3 kN (at 1100 rpm) were obtained in the bottom plate hole-and top plate hole-FESW joints respectively.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Bankong Daniel Bankong, Oluwafemi Joshua Ogundipe, Taiwo Ebenezer Abioye, Tunde Isaac Ogedengbe, Hussaini Zuhailawati, Taiwo Mike Adamolekun, Amos Babatunde Osasona, Muhammad Hafiz Hassan Wire arc additive manufacturing (WAAM) has gained significant attention in recent years as a cost-effective and efficient method for fabricating complex geometries. This study investigates the effects of cold forging and annealing on mechanical properties of AISI 308LSi wall fabricated using an automatically controlled gas metal arc welding on a CNC machine. The multilayer WAAM wall manufactured at an optimized parameters was first machined to a fairly smooth surface. Thereafter, the wall samples were differently subjected to annealing at 930°C and cold forging processes to improve the mechanical properties. Microstructural characterization of the post-processed and as-deposited samples were performed using optical and scanning electron microscopy while the tensile and hardness properties were investigated using Instron universal testing machine and Vickers hardness tester respectively. Annealing process was found to improve the tensile properties while the cold forging improved hardness of the deposited WAAM wall. These findings offer valuable insights into optimizing post-processing techniques for WAAM parts, especially 308LSi stainless steel and contribute to the advancement of this technology for industrial applications.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Omokafe Seun Michael, Esther Oluwafunmike Aduloju, Thompson Arakaseun The widespread corrosion of critical oil and gas infrastructure requires development of innovative and environmentally sustainable solutions. This research considers the repurposing of hitherto un-useful expired drugs to meet this challenge and to do so in ways that also puts stop to the menacing and illegal circulation of expired pharmaceuticals in developing economies. The corrosion inhibitory potential of expired paracetamol was evaluated for mild steel in acidic environment. Electrochemical analysis revealed that the corrosion current decreased from for the mild steel immersed in the blank/uninhibited 0.5M HCl environment to in the case of the sample in the 8g/l environment. The concentration of dissolved ions of iron in the acidic environment also followed this trend supported by the results obtained from the gravimetric analysis. Optical microscopy showed gradual covering of the corroding surface by a layer of inhibitor film with increasing concentration of the additive in the acidic environment. The corrosion inhibition efficiency increased with increasing concentration of the expired drug, reaching a maximum of 73.24% for 8.0 mM of expired paracetamol directly dissolved in the acid. Expired paracetamol acted as a mixed-type inhibitor for mild steel in 0.5M HCl and the corrosion inhibition process was spontaneous. All analyses agreed that expired paracetamol drug is capable of inhibiting corrosion of mild steel in HCl and that the corrosion inhibition is achievable without prior pretreatment. The research is fundamental as it attempts to lay some groundwork for further research towards developing viable and marketable product from this category of materials.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Ayopo Bamidele Alo, Olugbenga Oyedepo This research evaluates the performance of hot mix asphalt modified with fly ash and waste foundry sand for road development. Preliminary tests were conducted to determine material properties. Hot mix asphalt samples with varying percentages of granite, sand, stone dust, and bitumen (5%, 5.5%, 6%, 6.5%, and 7%) were produced using ASTM D6927 Marshall mix design. The optimum bitumen content (OBC) was found from the mix to be 5.7%. Using the same mix design, bituminous mixtures were created with waste foundry sand as a partial replacement for fine aggregate (10% - 50% at 10% intervals), along with granite, stone dust, and 5.7% bitumen (OBC). The mix with 40% replacement performed optimally. A new mixture, incorporating granite, sand, fly ash (10% - 60% replacement for filler material, at 10% intervals), and 5.7% bitumen (OBC), was produced. The optimal replacement percentage was 50%. A combination mix of the materials, based on derived optimums, achieved a stability value of 26.09 kN, meeting the Asphalt Institute's criteria. Microstructural analysis indicated a densely packed agglomeration of particles, implying good strength properties. This research demonstrates the viability of waste foundry sand and fly ash as alternative materials, enhancing the strength and flexibility of hot mix asphalt. Reusing these waste materials in road construction is a positive step towards sustainability.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Catherine Mayowa Ikumapayi, Joseph Adeniyi Ajayi, Akintunde Fasuba Concrete is a construction material that is widely embraced worldwide with a major disadvantage of environmental unfriendliness arising from the production process of cement, one of its vital components. Recent studies have found that replacing cement with pozzolans increases compressive strength, durability, and occasionally workability, although at a low replacement percentage. The low replacement level obtained can be improved upon with the use of superplasticizer to further enhance the workability and the compressive strength. Therefore, the primary objective of this study is to determine the effects of adding Costamix 200 superplasticizer and partially replacing cement with sawdust ash (SDA) for cement on the mechanical properties of the resultant concrete. Waste sawdust was collected, dried, and then burnt in a furnace for 60 minutes at 700°C. Concrete samples were made using 150 x 150 x 150 mm3 rectangular and 100mm cylindrical molds using a 1:2:4 mix ratio, 0.55 water cement ratio, a constant dosage of 1.8% superplasticizer (Costamix 200), and SDA at 0%, 5%, 10%, 15%, 20%, and 30% SDA respectively. The concrete samples were tested at 7, 14, 21, and 28 days for bulk density, split tensile strength, and compressive strength were carried out. The outcomes of the research show that the presence of costamix 200 and SDA at 0%, 5%, 10%, 15%, and 20% cement substitution resulted in compressive strength range of 18.91 N/mm2 to 25.00 N/mm2 at 28 days. The optimum value of 25.00 N/mm2 was recorded for 15% replacement making it ideal for use in structural applications such as beams, slab and column.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): S. L. Akingbonmire, C.O. Okonkwo, P.O. Kayode, K. Akinsanmi This study focuses on eliminating cracks partially in structures by adopting bacteria-based fibre and steel reinforced self-healing concrete. Two bacteria of the genus Bacillus were used, one was cultured from soil, while the other was cultured from parkia. These were subcultured using an algae medium to produce 13500 ml of washed bacteria cells, which were immobilized in 1,500 ml of silica gel. A nutrient solution was also prepared by mixing 171 g of yeast extract, 1710 g of urea, and 1710 g of calcium lactate in water. Water, polyvinyl alcohol (PVA), bacteria cells, and silica gel contributed to the total water content at a ratio of 0.22, 0.03, 0.225, and 0.225 respectively. 81 concrete cubes of and 72 reinforced beams of were cast using 1:2:4 mix ratio. Cracks were created on the surface of the cubes after casting with a 0.6 mm steel plate and were cured for 7, 14, and 28 days. After curing the reinforced beam for 14 days, cracks were created on 36 beams (healed specimen) out of which 18 numbers were cured for 7 days and the remaining were cured for 14 days. 18 beams out of the remaining 36 beams (sound specimen) were tested at 7 days while the remaining 18 were tested at 14 days. The compressive strength, water absorption, and sorptivity results showed that Bacillus spp. (from soil) performed better than the control and Bacillus spp. (from parkia).
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Moses Azeez Olayiwola, Davies Oladayo Folorunso, Moses Oladejo Tanimola The characterisation and insulating efficiencies of sawdust and rice husk in glass shavings reinforced termite clay-based (GSRTC) composite has been compared. Termite clay was unearthed from the Federal University of Technology, Akure (FUTA) campus in Ondo State. It was processed to obtain 150 μm undersize. Glass shavings were processed to obtain 106 μm undersize. The glass shavings were then mixed with the termite clay in a constant weight proportion of 10%. Sawdust and rice husk were processed to obtain 150 μm undersize. The prepared blended GSRTC powder was mixed with the sawdust, and the rice husk in 2, 4, 6, 8, and 10 wt.%. The resulting mixtures were compacted into cylindrical-shaped samples. The samples were dried and fired in a furnace at 1000°C for 2 hours. The chemical composition of GSRTC composite constituents was studied prior to the production of the composite. The control sample with only 10 wt.% of glass shaving possessed the highest: compressive strength; linear and volumetric shrinkage; bulk density; and thermal conductivity, while the sample with 10 wt.% of sawdust in GSRTC possessed the lowest: compressive strength (1.62 MPa); linear and volume shrinkage; bulk density (0.68 g/cm3); thermal conductivity (0.23 W/m-K).. Conclusively, the additive proportion and type affect composites' physical properties. An increase in additive proportion is accompanied by an increase in porosity, a reduction in porosity and bulk density. The compressive strength and thermal conductivity decreased with increasing additive content. GSRTC composites with sawdust additive possessed better insulating performance. However, GSRTC composite with rice husk additive displayed higher compressive strength.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Babatunde Kazeem Ayinde, Gafar Omotayo Oniyide, Adedapo Jacob Adeyemi This research was carried out to compare the performance of ANFO and Ammonium Nitrate on fragment size distribution by using the ANFO and AN as the column charge in blasting operations, measuring the fragmentation size after each blasting operation, characterizing the fumes evolving from the blasting operation in each case and compare the performance of the ANFO and AN. The densities of the rock deposit were derived as 2.638 g/m3 and 2.622 g/m3 for Block A and Block B respectively. The rebound hardness tests ranged from 47 to 61 for Block A and Block B from 48 to 54. The total explosive charge used for each of the blocks was 0.1 kg. The muckpile magnification ratio for Block A was 0.008 and Block B was 0.004. The fragmentation sizes for Block A range from 1.869 cm to 19.411 cm and Block B from 2.414 cm to 37.177 cm. The magnification ratio and fragment sizes show that Block A has better fragmentation than Block B. Ammonia gas was not present in the area of study before blasting but the fume emitted after first blasting with ANFO produced 0.08% of Ammonia gas and after the second blasting with AN 0.07% were produced. The oxygen level was reduced from 20.9% before blasting to 19.2% after the first blasting and 19.1% after the second blasting. It was deduced that blasting with ANFO generated more Ammonia gas than blasting with AN but the Oxygen level when ANFO is used was higher than when AN is used. Keywords: Blasting, density, explosive, fragmentation, magnification ratio
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Olawale Ibrahim Kolapo, Ayodeji David Olatise, Emmanuel Oluwadunsin Idowu, Segun Weyinmi Omejalile, Taiwo Ebenezer Abioye, Buliaminu Kareem The automotive industry faces a significant challenge in meeting the increasing demand for lightweight and eco-friendly vehicles with reduced energy consumption and lower air pollution. This challenge is driven by factors such as consumer preferences, strict government regulations, technological complexities, cost considerations and market acceptance. Aluminium metal matrix composites (AMMCs) are novel materials with high suitability to address this challenge. Currently, AMMCs used in the automotive industry are reinforced with conventional synthetic ceramic particulates and they have shown tremendous improvements over unreinforced alloys. These composites have wear resistance and strengths equivalent to that of cast iron but with about 67% less density. However, synthetic reinforcements are expensive, have limited availability, possess high abrasiveness, cause unwanted reactions, pose recycling difficulties and their production leads to the emission of greenhouse gases. It is now pertinent to consider the use of agricultural waste derivatives as possible substitutes for these conventional reinforcements. In this work, the various agricultural waste derivatives that have been used to reinforce Al matrixes were reviewed and the potentials of the resulting composites as promising candidates for lightweight automotive applications were assessed. It was concluded that agricultural waste derivatives contained hard ceramics particles which improved the mechanical, tribological, thermal and corrosion properties of AMMCs, making agro-waste derivatives reinforced aluminium metal matrix composites promising for the production of novel lightweight automotive components.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Muhammad A. Adamu, Emmanuel O. Ameh, Salami A. Kazeem, Mohammed Abdullahi, Uman Hassan Despite several advantages of hydroxyapatite, the main shortcoming is its low mechanical properties. The aim of the research study is the production and characterization of Rice Husk Ash reinforced hydroxyapatite ceramic composite for bone repair. The effect of Rice Husk Ash content and sintering temperature on the wear rate, physical and mechanical properties of the fabricated composite was investigated. The porosities obtained for the samples range from 39±0.1 to 56.53±0.14%. The porosity obtained in this study falls within the range of 40 and 90% which makes it suitable for osteo-integration. The trend from the mechanical properties shows that the addition of the rice husk ash significantly improves the measurement since it serves as a barrier to the propagation of cracks and consequently serves as an additional toughening mechanism. The wear rates obtained for the samples are 0.036, 0006, 0.0016, 0.009 for 0, 0.5, 1, and 1.5 wt.%RHA respectively. This shows that the wear rate of the samples reduces drastically with the addition of the rice husk.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Olaolu George Fadugba, Fidelis O. Ajibade, Bamitale Dorcas Oluyemi-Ayibiowu Municipal solid waste management continues to be an enormous challenge for developing countries such as Nigeria. With a rapidly increasing population and change in consumption choices in urban cities in Nigeria, the need to cater for and properly manage the increased volume and more diversified waste generated becomes an urgent issue for consideration. Storage and Collection of generated waste make up the crucial elements of waste management systems in any city. Sadly, though, just about a quarter of waste generated in Nigeria is collected. This paper compiles relevant information from recent studies made by researchers and authors on waste management systems in Nigeria to review the current state of the waste storage and waste collection systems in major cities in Nigeria using Lagos and Abuja as case studies. This study also summarizes the methods majorly used for the storage and collection of waste in Nigeria, making recommendations as and when necessary.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Ochuko Mary Ojo The continuous degradation of available water resources coupled with the high cost of conventional water treatment has led to alternative, sustainable and cost-effective methods of treating wastewater. This study investigated the efficiency of Carica papaya seeds in the coagulation of moderately turbid water while determining the optimum treatment dosage and evaluating the treatment efficiencies compared to the use of conventional Aluminum sulphate (alum). Moderately turbid wastewater was obtained from Ala River tributary in Akure, Ondo State, Nigeria. The coagulation experiments were carried out at room temperature in a jar test. The experiments were carried out using 0.2 g/L, 0.4 g/L, 0.6 g/L. 0.8 g/L, 1.0 g/L, 1.2 g/L and 1.4 g/L doses of Carica papaya seed powder. An alum dose of 1 g/L was used as a control dose. The pH, turbidity, total hardness, total dissolved solids (TDS), and biochemical oxygen demand (BOD) of the raw water and treated water samples were analyzed. The pH of the raw water sample was 7.8; after treatment, the pH ranged from 7.7 at 0.2 g/L to 8.0 at 1.0 g/L treatment dose with Carica papaya seed powder. The optimum dose for turbidity removal was found to be 0.8 mg/L which amounted to 74.5% turbidity removal efficiency compared to 93.1% for alum. The hardness of the raw wastewater sample was 102 mg/L. After treatment, the hardness reduced from 99.4 mg/L at 0.2 g/L treatment to 77.6 mg/L at an optimum dose of 0.8 g/L. The TDS reduced from 564 mg/L at 0.2 g/L treatment with Carica papaya seed powder to 388 mg/L at an optimum dose of 0.8 mg/L amounting to a 78.9 % contaminant removal. The percentage BOD removal at 0.8 g/L of Carica papaya treatment was 86.3% while at 1.0 g/l, it was 100%. This study demonstrated that Carica papaya seeds is useful for the removal of contaminants from moderately turbid wastewater at varying percentages under different doses of papaya seeds.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Michael Kanisuru Adeyeri, Ojo Victor Ademeso, Abel Bayowa Nwoko The unkempt state of many ceiling fans in offices, homes and industries due to poor maintenance in term of cleaning and the wastage of energy as a result of carelessness in appliance usage inform the design of a ceiling fan with autonomous capability. The design of the ceiling fan was done using appropriate design equations and Solidworks CAD software. Different concepts were conceived and the best concept was determined using one of the Multi – Criteria decision Tools named Pugh Matrix Method. After which, simulation was done using ANSYS and Proteus 8.1 design suite to test functionality of the design. The outcome shows that at no load in the room, the ceiling fan switches off automatically and also when occupants are in the room with an increase in temperature above ambient temperature (25 °C), the ceiling fan switches on. The simulation results analysis of stress, strain, shear force, deflection, factor of safety and bending moment on the embedded cleaner gave 112.717 MPa, 0.007496, 5 N, 60.28 mm, 1.8346 and 0.8965 Nm respectively. Furthermore, the result revealed that the autonomous capability of the cleaning mechanism gave an efficiency of 85%. The cost to implement this innovation is estimated at twenty five dollar.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Akinlolu Adediran Ponnle, Oluwabukola Arike Ojediran, Ajibike Akin-Ponnle, Samuel Adenle Oyetunji Visible light communication has advantages over acoustic and radio wave transmissions in free-space and underwater. The optical transmitters are usually light emitting diodes or laser diodes, and the optical receivers are usually photodiodes or its variants. Solar panels are used for solar energy harvesting to electricity, but the panels are also available in small sizes, and hence, are finding increasing use in optical communications due to larger aperture compared to photodiodes. This work investigated by experiments the characteristics of solar panels as receivers in visible light communication (VLC). In the work, four solar panels of different physical sizes were selected for experiments and measurement. Two characteristics important to communication were investigated. First is the internal resistance at different low illumination levels of white light. Second is response to sinusoidally varying intensity of white light at varying frequencies. For the first study, two of the four panels were investigated; and for the second study, the four solar panels were investigated. An array of seven white LEDs was used as the light source. Also, underwater data communication in saline water was performed for one of the solar panels, and a photodiode in comparison. Results showed that under steady illumination, the internal resistance is both illumination level-dependent and surface area-dependent. It decreases with increase in illumination level, and surface area. Also, the rate of decrease of the internal resistance with illumination increases with surface area. For the frequency response, the cut-off frequency of the solar panel is surface area-dependent, and load-dependent. It decreases with increase in surface area, and increases with decrease in load resistance values (increased loading). For data communication, the maximum data rate obtainable with the solar panel is less to that of the photodiode. The frequency response is important in considering the bandwidth of the solar panels, which also varies with the load, while the internal resistance is important in maximum power point tracking and impedance matching with front end circuits in optical communication receivers.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Sameul Olanrewaju Aremu, Adegoke Oladipo Melodi, Michael Rotimi Adu This paper presents performance-based study of the Nigerian Transmission Grid (NTG), having about 27 power stations, 50 transmission (330/132kV) stations and 150 bulk load centers (132/33kV). Power stations and transmission grid are designed to operate at a level close to installed capacities, to achieve high efficiency. However, due to some technical limitations and maintenance factors, not all the elements may be available at all operating times. Therefore, the available generations may not equal the installed capacity; also, the load demand (consumed) on the grid may not equal the installed transmission capacities. This study evaluates the capacity of the transmission grid considering the installed and available generation capacity and three components of transmission load: actual load demand (LD), transmission wheeling capacity (TWC) and transmission load capacity (TLC). Obtained system data were used to create virtual simulator for the transmission grid, using Power System Analysis software (NEPLAN), which uses Newton Raphson Algorithm. The results established that the power generation on the grid must be maintained at the level of installed capacity to deliver the TWC and TLC load component to mitigate the practice of rotational power transmission and distributions currently being adopted in electricity transmission and distribution in Nigeria. It was established that the transmission capacity of the current transmission network is capable of accommodating and delivering power more than the current installed generation capacity. It is recommended that efforts be geared towards improving the generation capability of the grid for efficient power transmission and distribution. Keywords: grid capacity, transmission grid, load, system collapse, voltage stability
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Patrick Taiwo Ogunboyo, Omojola Ogunlade To allow for optimum operation of the secondary system of lines, it is essential that the performance of the system be evaluated. Optimal functioning refers to the most desirable and favorable system of operation such as: improved system reliability, adequate and satisfactory electric potential profile, no imbalances in the phases of electric potential and electric charge, complete absence of overloading of electrical conductor used and energy converting devices and approved and allowable loss. This investigative research assesses the efficiency of the distribution system of lines resulting from electric potential deviation, electric potential imbalances, electric potential losses and electric potential fluctuation through the use of MATLAB/Powerlib tools. This research offers most desirable and favourable assessment of Typical, Sub-Saharan Africa secondary unbalanced system of lines. The system of lines was designed with approved and accepted system of line parameters for secondary Sub-Saharan Africa typical system of lines through the use of MATLAB/Powerlib software. The desire outcome got from the MATLAB model with the 500 meters distance for unbalanced system of lines is within permitted actual electric potential limit of minus five per cent for electric potential loss, plus and minus five per cent for electric potential deviation, electric potential imbalances is less than 2 per cent, and the electric potential profile at the end users is within 0.95 and 1.05 per-unit.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Abiodun Sulaimon Sobayo, Oluwaseun Ibrahim Adejumobi, Isaiah Adediji Adebisi, Daniel Oluwasegun Adams Static security is the property of power system to maintain steady or stable operating state when contingencies such as line outages or component failures occur to avoid economic and technical losses. This study assessed the static security of the Nigerian 330 kV, 30-bus electric power transmission grid using a contingency approach. The steady state performance of the power system was modelled using Newton-Raphson based load flow equations and simulated in ETAP software environment. Bus voltage and line loading violations were determined by observing the voltage profile and line flows compliance with the voltage statutory limit of 0.95 to 1.05 p.u. and 80% loading of the thermal (MVA) limit respectively. N-1 contingency evaluation was conducted on fifty lines of the considered network. Performance index (PI) of the outage lines was determined and used to rank each of the contingency cases. Load flow analysis revealed that New – Haven, Onitsha, Gombe, Jos, Kano and Calabar with voltage magnitudes of 0.9003, 0.9468, 0.6608, 0.8141, 0.8138 and 0.9319 p.u. respectively violated the voltage statutory limit while Okapi-Calabar and Alaoji-Calabar with loading of 101.6 and 84.19 % respectively exceeded the recommended 80% loading of the MVA limit. The system total active line loss was 218.08 MW. Contingency analysis results ranked Benin-Onitsha and Ikeja West-Aiyede having the PI of 80.73 and 3.56 as the most and least critical lines respectively. This study established the suitability of contingency method for the assessment of security of a large-scale network such as the Nigerian electricity grid.
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Abstract: Publication date: 23 July 2024 Source: Advances in Science and Technology Vol. 154 Author(s): Oluwadare Raphael Olakunle, Adegoke Oladipo Melodi In this study, power flow analysis was carried out on a typical Nigerian 43-bus radial distribution network feeder incorporated with non-linear loads using NEPLAN software to determine its operating parameters. Also, adequate reinforcements were provided to achieve power system parameters within recommended limits and the associated costs of implementation evaluated. The results obtained showed its voltage profile ranges from 87.12% to 97.07% and the harmonic distortion level (THDV) ranges from 4.5% to 6.43% which is in violation of recommended ±5% of bus nominal voltage and 5% harmonic distortion limit for 11 kV nodes. A hybrid optimization technique that combine Genetic Algorithm (GA) and Direct Search method was used in the sizing and location of capacitor bank and passive harmonic filters to reinforce the distribution networks. The results obtained showed that voltage profile improved to the range of 96.73% to 100.27% and the THDV improved to the range of 2.99% to 4.46% with active power loss reduction from initial 707.24 kW to 558.1 kW after reinforcement. The estimated investment cost options on reinforcement devices ranges from 48 million Naira to 138.81 million Naira with a payback period of three (3) years for an optimum reinforcement billing charge of ₦10/kWh increase on tariff charge.
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