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Research Article
Impact of Reactive Power Support on Voltage Stability in High PV Penetration Weak Grids: A Seasonal Analysis of the River Zone Network in Niger
Issue:
Volume 14, Issue 3, September 2026
Pages:
99-107
Received:
4 May 2026
Accepted:
15 May 2026
Published:
23 July 2026
DOI:
10.11648/j.ajee.20261403.11
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Abstract: The increasing penetration of utility-scale photovoltaic (PV) systems in weak transmission grids introduces significant reactive power deficiencies that threaten voltage stability, particularly in developing countries where compensation resources are limited. This paper investigates the impact of multi-step switched capacitor bank reactive power support on voltage stability in the River Zone (RZ) network of Niger, a weak transmission grid undergoing significant PV capacity expansion. A quasi-dynamic simulation framework solves time-series alternating current (AC) power flows at hourly resolution across three representative seasonal periods (January, May, and August) under two scenarios: a baseline case without reactive compensation, and a mitigation case with dynamic hysteretic capacitor bank control. Voltage profiles (VP) and a bus-level Voltage Stability Index (VSI) serve as the primary assessment metrics. In the baseline scenario, May emerges as the most critical period, with VSI outliers descending to 0.64~p.u. and multiple buses sustaining prolonged operation below 0.80~p.u. Under the mitigation scenario, reactive compensation consistently lifts the VSI above the 0.90~p.u. stable threshold across all seasons and eliminates all collapse-risk outliers. The results demonstrate that multi-step capacitor bank support is an effective and seasonally robust voltage stabilization strategy for weak Sub-Saharan African grids with high PV penetration. The findings further highlight the need for systematic reactive power planning and dynamic compensation deployment as an integral component of renewable energy integration strategies in resource-constrained grid environments.
Abstract: The increasing penetration of utility-scale photovoltaic (PV) systems in weak transmission grids introduces significant reactive power deficiencies that threaten voltage stability, particularly in developing countries where compensation resources are limited. This paper investigates the impact of multi-step switched capacitor bank reactive power su...
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Research Article
Multicomponent Iridium-Based Alloy Catalysts for Enhanced Alkaline Hydrogen Oxidation Reaction
Yanfu Tong,
Zhiyuan Liu,
Xuejin Li,
Wei Xing*
Issue:
Volume 14, Issue 3, September 2026
Pages:
108-116
Received:
25 May 2026
Accepted:
25 June 2026
Published:
6 August 2026
Abstract: The sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline media, primarily arising from the linear scaling relationship between H* and OH* adsorption energies on catalyst surfaces, remains a critical bottleneck for anion-exchange membrane fuel cells (AEMFCs). In this study, we propose a multifaceted approach to overcoming the current limitations of scaling by synthesising Ir-based ternary alloys with diverse oxophilic metals, including Mo, Ru, and Nb. The RuIrMo@MHCS catalyst, featuring a face-centred cubic single-phase solid solution with uniformly dispersed nanoparticles on hollow carbon spheres, exhibits a kinetic current density of 18.04 mA cm–2 at 50 mV overpotential and an exchange current density of 6.79 mA cm–2. This is a significant improvement over the performance of commercial Pt/C, with factors of 6.14 and 5.66, respectively. Additionally, the catalyst demonstrates excellent long-term stability. X-ray photoelectron spectroscopy reveals electron transfer from Ir to Ru upon Ru doping. Density functional theory calculations demonstrate that Ru incorporation downshifts the d-band centre of Ir, thereby moderately weakening H* adsorption (ΔGH* = –0.38 eV) while enhancing OH* adsorption on Mo sites. This adaptable calibration of intermediate adsorption energies circumvents the linear scaling constraint and substantially promotes alkaline HOR kinetics. The findings of this study corroborate the hypothesis that multicomponent alloying is an effective strategy for synergistic optimisation of H* and OH* binding, thus providing a rational design pathway for high-performance alkaline HOR catalysts.
Abstract: The sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline media, primarily arising from the linear scaling relationship between H* and OH* adsorption energies on catalyst surfaces, remains a critical bottleneck for anion-exchange membrane fuel cells (AEMFCs). In this study, we propose a multifaceted approach to overcoming the curre...
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Research Article
Study on the Particle Size and Specific Surface Area of Iron-Based Oxygen Carrier Modified Directionally by Fly Ash Powder
Issue:
Volume 14, Issue 3, September 2026
Pages:
117-125
Received:
10 June 2026
Accepted:
27 July 2026
Published:
26 August 2026
Abstract: Iron-based oxygen carriers are among the most widely used carriers in chemical-looping hydrogen production technology, yet their pore size and specific surface area remain critical factors limiting reaction efficiency. Meanwhile, the potential of fly ash—rich in silicon, aluminum, as well as sodium, potassium, and calcium—to enhance the reactivity of iron-based oxygen carriers represents a strategic approach toward transforming waste into valuable resources in coal-fired power plants. In this study, synthetic iron-based oxygen carriers were prepared via co-precipitation, with 2 wt% fly ash added for comparative analysis. BET results indicate that incorporating fly ash increases the specific surface area from 12.56 m2/g to 27.45 m2/g, while also improving total pore volume and mesopore content. XRD and SEM analyses reveal that fly ash does not alter the crystalline phase but instead acts as an inactive framework, suppressing abnormal crystal growth at high temperatures and locally creating voids that form a complex interwoven pore structure. Single-particle crushing pressure tests demonstrate that adding 2 wt% fly ash significantly enhances mechanical strength, contributing to greater structural stability. This work integrates performance improvement of iron-based oxygen carriers with comprehensive utilization of fly ash, providing valuable insights for further exploration and application of chemical-looping hydrogen production technology.
Abstract: Iron-based oxygen carriers are among the most widely used carriers in chemical-looping hydrogen production technology, yet their pore size and specific surface area remain critical factors limiting reaction efficiency. Meanwhile, the potential of fly ash—rich in silicon, aluminum, as well as sodium, potassium, and calcium—to enhance the reactivity ...
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Research Article
CFD Simulation via User-Defined Functions and Resizing of a Solar Dryer for Processing 25 kg of Pineapple
Issue:
Volume 14, Issue 3, September 2026
Pages:
126-139
Received:
16 June 2026
Accepted:
30 June 2026
Published:
8 September 2026
Abstract: This article presents an optimization and numerical simulation (CFD) study of an indirect solar dryer designed for pineapple drying, aiming to reduce critical post-harvest losses in West Africa, particularly in Benin. Unlike many previous studies that are often limited to modeling an empty drying chamber, this work evaluates the system under real operational conditions by integrating an active load of 25 kg of pineapple. To achieve this, the authors utilize the ANSYS Fluent solver and develop three specific user-defined functions (UDF) to dynamically simulate coupled heat and mass transfers, thereby accurately representing the airflow resistance and active water evaporation within the product's porous matrix. Structurally, the system underwent several major geometric improvements, including resizing the solar collector to 5.54 m2 to provide the 46.53 × 106 J required to extract 20.59 kg of water, and optimizing the spacing between trays to 250 mm. The results demonstrate that this new configuration effectively eliminates dead recirculation zones and ensures a homogeneous distribution of hot air. Quantitatively, the system maintains a highly uniform drying atmosphere, with temperature variations between the five trays limited to a narrow range of only 0.4°C (52.9°C to 53.3°C) and an inter-tray hygrometric gradient of less than 0.04%. While the model demonstrates high numerical robustness with a minimum orthogonal quality exceeding 0.1, the current lack of specific experimental validation for this resized configuration is acknowledged as a limitation, providing a foundation for future in situ correlation studies.
Abstract: This article presents an optimization and numerical simulation (CFD) study of an indirect solar dryer designed for pineapple drying, aiming to reduce critical post-harvest losses in West Africa, particularly in Benin. Unlike many previous studies that are often limited to modeling an empty drying chamber, this work evaluates the system under real o...
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Research Article
Comparative Thermo-Electrical Performance of Monocrystalline and Polycrystalline Silicon Photovoltaic Modules Under Extreme Temperatures
Issue:
Volume 14, Issue 3, September 2026
Pages:
140-150
Received:
24 July 2026
Accepted:
12 August 2026
Published:
8 September 2026
Abstract: Operating temperature is a critical factor limiting the performance and reliability of photovoltaic (PV) systems, particularly in Sahelian regions where modules are exposed to substantial thermal fluctuations. Although temperature effects on PV performance have been widely investigated, experimental evidence remains limited on the comparative thermo-electrical response of monocrystalline and polycrystalline silicon modules under a broad range of extreme temperatures while simultaneously considering electrical characteristics, effective temperature coefficients, and thermal dynamics. This study addresses this gap through a controlled experimental comparison of both technologies over a temperature range of 5–70°C at a constant irradiance of approximately 450 W.m-2, representative of moderate solar operating conditions. A solar simulator coupled with a PV150 photovoltaic analyzer was used to systematically characterize the current–voltage (I–V) and power–voltage (P–V) characteristics, energy conversion efficiency, effective maximum power temperature coefficients, and heating and cooling dynamics of the two PV technologies. The results demonstrate a consistent temperature-dependent degradation of electrical performance: increasing temperature slightly increases short-circuit current, whereas open-circuit voltage, maximum power output, and conversion efficiency progressively decline. Between 30°C and 70°C, the efficiency of the monocrystalline module decreased by 11.92%, compared with only 6.68% for the polycrystalline module, while cooling to 5°C increased efficiency by 8.52% and 14.57%, respectively. The experimentally determined maximum power temperature coefficients were −0.30%.°C-1 for the monocrystalline module and −0.17%.°C-1 for the polycrystalline module, revealing a markedly lower thermal sensitivity and greater thermal stability of the polycrystalline technology under the investigated conditions. Beyond quantifying conventional temperature-induced losses, the originality of this study lies in the integrated experimental assessment of electrical degradation, effective thermal sensitivity, and transient thermal behavior across an extended temperature range under controlled irradiance, providing experimentally derived evidence relevant to harsh Sahelian environments. These findings have direct practical implications for PV technology selection, performance prediction, thermal derating, and the design of thermal management strategies, particularly for installations exposed to severe heat stress. The results also provide experimental benchmarks for improving temperature-dependent PV performance models and supporting the development of climate-adapted operation and maintenance strategies for high-temperature photovoltaic systems.
Abstract: Operating temperature is a critical factor limiting the performance and reliability of photovoltaic (PV) systems, particularly in Sahelian regions where modules are exposed to substantial thermal fluctuations. Although temperature effects on PV performance have been widely investigated, experimental evidence remains limited on the comparative therm...
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,
Ibrahim Yaou Ladoua
