Research Article
Voltage Stability Enhancement in North West Ethiopia’s Power Grid Using Contingency Analysis and PSO-Based Load Shedding
Issue:
Volume 11, Issue 3, June 2025
Pages:
41-58
Received:
15 August 2025
Accepted:
28 August 2025
Published:
9 October 2025
Abstract: This study presents an integrated methodology to enhance voltage stability and operational security in the North West Ethiopian power grid by addressing system vulnerabilities and optimizing load-shedding strategies. A hybrid simulation-optimization framework is developed, combining DIgSILENT PowerFactory-based contingency analysis with Particle Swarm Optimization (PSO)-driven intelligent load shedding in MATLAB. The modeled power network comprises 2 generators, 15 buses, 15 transmission lines, and 3 external grids. Vulnerability assessment is conducted using Voltage and Overload Performance Indices (PIV and PIP) to rank critical elements under various contingencies. The analysis identifies the BDII-230 to GOII transmission line as the most vulnerable, where its outage causes voltage drops to 0.908 p.u. at Gondar and 0.923 p.u. at Metema, both falling below acceptable operational limits. Under increased load conditions (50% and 75% load factor), the Gondar bus experiences severe voltage deterioration, dropping to 0.8879 p.u., which significantly stresses system stability. Through PSO-based load shedding, the voltage at Gondar is restored to 0.9538 p.u., demonstrating a 7.4% improvement, while excessive real power (e.g., at BDII230) is reduced from 1.3235 to 0.8958 p.u. under 50% load increase, effectively stabilizing the system. The proposed PSO framework outperforms conventional load-shedding mechanisms by factoring in bus sensitivity and minimizing overall power shed while maximizing voltage recovery. The results provide actionable insights for grid operators and planners, establishing a reliable and scalable method for real-time contingency response in developing power networks.
Abstract: This study presents an integrated methodology to enhance voltage stability and operational security in the North West Ethiopian power grid by addressing system vulnerabilities and optimizing load-shedding strategies. A hybrid simulation-optimization framework is developed, combining DIgSILENT PowerFactory-based contingency analysis with Particle Sw...
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Research Article
Integrated Fermentation of Fruit Processing Wastes into Bioethanol by Saccharomyces Cerevisiae and Aspergillus Niger
Issue:
Volume 11, Issue 3, June 2025
Pages:
59-65
Received:
13 August 2025
Accepted:
25 August 2025
Published:
14 October 2025
DOI:
10.11648/j.ajme.20251103.12
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Views:
Abstract: The detrimental environmental impact of fossil fuels, primarily driven by harmful greenhouse gas emissions, necessitates the urgent development of sustainable alternative energy sources. Concurrently, effective municipal solid waste management, particularly concerning organic fractions, presents a significant challenge in urban centers like Arba Minch, Ethiopia. This research addresses both issues by investigating the valorization of locally abundant fruit peel waste specifically from bananas and mangoes—into bioethanol, a viable renewable fuel. The study employed a bioprocessing strategy utilizing microbial co-culture. Waste peels were pre-processed by chopping into 3-5 cm pieces, followed by seven days of sun-drying to facilitate milling and enhance substrate accessibility. The resulting dried powder, rich in fermentable cellulose and hemicellulose, served as the primary feedstock. Bioethanol production was achieved through a seven-day simultaneous saccharification and fermentation (SSF) process using a co-culture of Aspergillus niger (for enzymatic hydrolysis/saccharification) and Saccharomyces cerevisiae (for ethanol fermentation). The fermentation media was maintained at a pH of 5.5-6.0 and a temperature of 30°C. An initial phase involved agitation on a dry shaker for two days to ensure mixing and oxygen transfer for microbial growth, followed by static incubation to promote anaerobic fermentation. Post-SSF, the broth underwent distillation to recover the bioethanol. Qualitative analysis confirmed ethanol production, while quantitative yield was determined spectrophotometrically. Results demonstrated that the mixed inoculum of A. niger and S. cerevisiae achieved a substantial ethanol yield of 79% from the mixed peel substrate after seven days. Notably, comparative analysis revealed that A. niger monoculture fermentation produced a significantly higher yield of 77% ethanol relative to S. cerevisiae alone. This work successfully establishes a practical method for converting problematic fruit peel waste from Arba Minch into valuable biofuel, highlighting the particular efficacy of A. niger in this process.
Abstract: The detrimental environmental impact of fossil fuels, primarily driven by harmful greenhouse gas emissions, necessitates the urgent development of sustainable alternative energy sources. Concurrently, effective municipal solid waste management, particularly concerning organic fractions, presents a significant challenge in urban centers like Arba Mi...
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Yalew Gebru Workie
