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All Journal International Journal of Electrical and Computer Engineering International Journal of Renewable Energy Development
Mat Said, Dalila
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Computer Science & IT Control & Systems Engineering Earth & Planetary Sciences Electrical & Electronics Engineering Energy Engineering

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Hotspot temperature analysis of distribution transformer under unbalanced harmonic loads using finite element method Mohd Wazir, Muhammad Haziq; Mat Said, Dalila; Mohd Yassin, Zaris Izzati; Abd Wahid, Siti Aisyah
International Journal of Electrical and Computer Engineering (IJECE) Vol 14, No 2: April 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v14i2.pp1287-1298

Abstract

In an electrical power distribution system, harmonic distortion is the most prominent power quality problem that causes long-term adverse effects such as failure of distribution transformers. Considering that most transformer problems are caused by heat losses due to the presence of harmonics, it was decided to use a numerical method with the highest accuracy, finite element method (FEM) to analyze the hot spot temperature (HST) of the thermal distribution transformer model. Through the use of COMSOL Multiphysics software, three phases of unbalanced harmonic loads are considered, which contribute to three different total harmonic distortion current (THDI) levels and five different insulation temperature classes. Using the IEEE C57.110-2018 guidance, the simulation outputs are then verified with HST results from the HST mathematical model. The findings indicated that with the increased loadings, the unbalanced harmonic currents have impacted the HST increment and distinguished the HST values between the phases.
Multi-objective optimisation and sensitivity analysis of component influences on efficiency in air-based bifacial photovoltaic thermal systems (B-PVT) Rajani, Ahmad; Mat Said, Dalila; Noorden, Zulkarnain Ahmad; Ahmad, Nasarudin; Arifin, Muhammad Subhan; Komarudin, Udin; Atmaja, Tinton Dwi; Subagyo, Subagyo; Fudholi, Ahmad
International Journal of Renewable Energy Development Vol 13, No 4 (2024): July 2024
Publisher : Center of Biomass & Renewable Energy (CBIORE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.61435/ijred.2024.60212

Abstract

Bifacial Photovoltaic Thermal (B-PVT) technologies have seen significant advancements in sustainable energy production by converting solar energy into useful electric and thermal energies simultaneously. The present study explored the optimisation of these systems by first performing sensitivity analysis on design parameters to identify key variables affecting their performance efficiencies. The system design and performance were then studied simultaneously using a multi-objective optimisation algorithm NSGA-II. It was found that increasing packing factors from 0.4 to 0.8 leads to a 15% increase in both electrical and thermal efficiencies, while an asymmetry in channel depths could lead to an 8% increase in thermal efficiency.  Key design parameters such as transmissivity cover, mass flow rate, packing factors and channel depth ratios were found to have the most significant influence on overall system performance. Multi-objective optimisation of design variables results in a Pareto front describing trade-offs between solutions of conflicting objectives of performance. Optimisation with preferences towards overall efficiency over temperature differential produces solutions with a high overall efficiency yield of 70.79%, requiring specific values for mass flow rate (0.197 kg/s) and channel ratio (0.129), however at the expense of a reduced temperature differential of 5.12oC. Solutions with a balanced preference towards both objectives could produce a solution that is less biased in performance.
An electro-thermal modeling of distribution transformer for hottest spot evaluation under photovoltaic-induced harmonics Mohd Wazir, Muhammad Haziq; Mat Said, Dalila; Md Sapari, Norazliani; Mohamed Yunus, Mohamed Shahriman; Mohd Yassin, Zaris Izzati
International Journal of Renewable Energy Development Vol 14, No 3 (2025): May 2025
Publisher : Center of Biomass & Renewable Energy (CBIORE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.61435/ijred.2025.60959

Abstract

Elevated winding insulation temperature, driven by harmonic distortions, is a key factor in transformer lifespan reduction. Conventional models often oversimplify the effect of combined current and voltage harmonics. This paper proposes an electro-thermal modeling approach, incorporating dual heat sources from core and winding domains, to enhance HST estimation in distribution transformers affected by photovoltaic-induced (PV)-induced harmonic losses. A sophisticated numerical approach, Finite Element Analysis (FEA), is employed using COMSOL Multiphysics software, with a 250-minute time-dependent study assessing thermal effects. The results, verified against a mathematical model approach based on IEEE C57.110-2018 guidance, demonstrate that higher levels of harmonics lead to a rapid increase in HST, accelerating the time to reach the aging factor temperature and consequently diminishing the transformer’s operational lifespan. Specifically, the per-unit life of the transformer decreases from 0.219 in Case 1 to 0.154 in Case 2 and 0.027 in Case 3, while the aging acceleration factor increases from 4.310 to 5.683 and 21.7, respectively. The methods showed over 95% alignment with the mathematical modeling approach, confirming the model’s precision in its predictive capability. The novelty of this study lies in its enhanced electro-thermal framework, which overcomes the limitations of conventional methods by integrating dual heat sources and providing a refined assessment of transformer aging under harmonic distortions. This advancement offers a more precise and computationally efficient approach for assessing transformer thermal stress under harmonic distortions.
Co-Authors Abd Wahid, Siti Aisyah Ahmad Fudholi Ahmad, Nasarudin Arifin, Muhammad Subhan Komarudin, Udin Md Sapari, Norazliani Mohamed Yunus, Mohamed Shahriman Mohd Wazir, Muhammad Haziq Mohd Yassin, Zaris Izzati Noorden, Zulkarnain Ahmad Rajani, Ahmad Subagyo Subagyo Tinton Dwi Atmaja