Ethiopia Institute of Technology- Mekelle
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Item Distributed Power Flow Controller Based Power Quality Improvement for Grid Connected Wind Farm- Case Study Ashegoda Wind Farm(Mekelle University, 2025-09-23) Ashenafi SelemaGrid penetration level of renewable energy is growing and merging dramatically. However, poor power quality creates a major integration and operation problems. Ashegoda wind farm represents Ethiopian first large scale wind power installation, having a total rated capacity of 120 MW. The substation is equipped with two 230kv buses that interconnect Lachi and Alamata substations. In the analyzed system, both transmission lines experienced high reactive power flow approximately 43MVAr and more than 3% current total harmonic distortion (THD), which leads to additional power loss, voltage drop, equipment overheating, and network congestions. On the other hand, the on-load tap changer (OLTC) transformer used to support voltage sag, swell, under-voltage, and over-voltage has slow response time up to 10 seconds per tap, and creates transformer overheating and mechanical fatigue. To solve such integration challenges, the incorporation of a distributed power flow controller (DPFC) with in the system is necessary for improved power quality and reliability. This study analyzed and modeled the integration, impact, cost benefit analysis, and Genetic Algorithm (GA) based optimal sizing and placement of DPFC for Ashegoda wind farm. The objective was to model, simulate, and asses its impact on voltage stability, reactive power compensation, and steady state and dynamic performance. The result indicated that, without DPFC the 230kv system operated at under-voltage of 0.89 pu with 5% current THD at bus 690v. After integration of 8MVA series and 25MVA shunt DPFC controller, the voltage profile is improved to 0.96 pu and current THD is minimized to 1.8%. Integrating DPFC exhibited excellent performance in maintaining voltage stability and limiting short-circuit current levels under different fault scenarios. The cost benefit analysis was carried out over a 20-year period. The total net present value (NPV) is estimated around $15,310,316.0 US dollars, while the total investment cost amounts $7,883,000.00 US dollars. By implementing the system, Ethiopian electric utility is expected to gain $7.5 million US dollars profit without considering scrap value. Generally, the researcher proved that DPFC is technically and economically feasible. MATLAB/Simulink 2018a and Excel-2013 was employed to model, simulate, and analyze the proposed DPFC system.Item Sustainable Design and Development of ceiling board from waste garment fabric reinforced composites with sisal fiber(Mekelle University, 2025-06-13) BRKTI MERDUThis study focuses on converting textile waste into a useful resource by utilizing it in to new product which is ceiling boards. The textile waste materials were collected from a local textile factory, MAA Garment. And it combined with sisal fibers as reinforcement with unsaturated polyester matrix. These recycled materials can be used to successfully develop composite materials that exhibit high strength, rigidity and ideal weight ceiling board applications. Different structural configurations were prepared with a 30/70% fiber-to-polyester resin ratio using randomly oriented cut waste fabrics: SSS (S1), SFS (S2), FSF (S3), and SSS (S4). The materials were mixed manually in the fabrication process. Demonstrating waste fabric and sisal fiber hybrid polyester composite laminates can effectively replace gypsum ceiling boards which offering notable environmental benefits and promoting the recycling of waste into functional construction materials are the two key goals of this research. Samples were prepared via the hand lay-up method, with fiber-to- polyester resin weight ratio 30/70%. And the sisal fiber were treated by alkali to enhance interfacial adhesion and remove impurities. Those treatment of fiber leads to enhance mechanical and physical properties of the laminate. This laminate pass through a series of experimental tests to evaluate the compressive strength, tensile strength, flexural strength, impact strengths, density, and water absorption rate. Finally the laminate shows good mechanical properties especially in flexural, tensile strength and water absorption. The optimized laminate achieved a 29% reduction in weight compared to gypsum boards, reducing from 12 kg to 8.49 kg. According to literature-based optimization, the water absorption of the laminate was only 5%, which represents a 54.5% reduction compared to lightweight cement boards, 50% compared to gypsum ceiling boards, and 44% compared to fiber cement boards (DORCK brand). To determine the optimal laminate configuration, the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method was employed. The analysis revealed that the F-S-F (S3) layup was the most effective. This optimal laminate, arranged in a 90°–45°–90° orientation, was further optimized using a Genetic Algorithm (GA) in MATLAB and its performance validated through re-analysis in ABAQUS software.Item Design and Optimization of Bamboo/Glass Fiber Reinforced Epoxy Composites for Sustainable Wall Panel Application(Mekelle University, 2025-05-19) Amelewerk HalefomThe increasing demand for sustainable construction materials has driven interest in natural fiber reinforced composites as eco-friendly alternatives to conventional materials. This study focuses on the design and optimization of bamboo/glass fiber-reinforced epoxy composites for application in sustainable wall panels, aiming to achieve a balance between mechanical performances, weight reduction, improve water resistance and sustainability. Different stacking sequences (B-G-B, G-B-G, G-G-B, and B-B-B) of bamboo and glass fibers were fabricated using the hand lay-up technique, preparation of 40% fiber and 60% of epoxy matrix incorporating alkali-treated bamboo fibers to improve interfacial bonding. The mechanical and physical properties of the fabricated composites were experimentally determined according to ASTM standards. A multi-criteria decision-making approach, using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), was employed to identify the optimal composite configuration. And it tells that G-B-G, characterized by a stacking sequence comprising 30% Bamboo, 10% glass, 60% epoxy, stands out as the optimal choice. The structural behavior of the optimized wall panel design was analyzed using Classical Lamination Theory. The optimization process, incorporating a genetic algorithm in MATLAB, aimed to minimizing weight and the constraint function is Tsai-Wu failure criterion. It results weight of the composite is 23.04kg, which reduced weight of the plywood weight by 15%, gypsum board by 5.8% and concrete panel by 38.4% and brick by 36%. Using literature review optimization, the water absorption of composite is 2.98% which reduced water absorption of the plywood by 7.11% of the gypsum board dry well is 9.11%, and concrete panel 2.11%, brick panel reduce by 8%. The optimized results were validated using ABAQUS of FEA. The maximum stress obtained from Genetic algorithm is 4.466Mpa and the maximum Von Mises stress is 8.511Mpa. The maximum deformation of the composite laminate is 12.2mm. This is less than the ultimate strength, proving the composite wall panel is safe and shows the safety factor is 2.5 against failure. The results of this study contribute to the development of sustainable and high performance wall panels using locally available bamboo resources.