Xinhao Lin¹, Lei Yu¹, Shuyin Duan¹, Yinliang Liu¹, Lvzerui Yuan¹, Xiao Chen^1,*, Yiqing Lian²

Energy Engineering, DOI:10.32604/ee.2026.072845

Abstract To address the operational challenges posed by renewable energy generation uncertainty and load fluctuations in DC microgrids, this paper proposes a hierarchical coordinated optimization control strategy for electricity-hydrogen hybrid DC microgrids (EH-DC-MG). The strategy aims to leverage the synergistic advantages of hybrid electricity-hydrogen energy storage to simultaneously achieve multiple objectives, including economic system operation, efficient utilization of renewable energy, and reliable power supply. The upper optimization scheduling layer formulates a mixed-integer linear programming model with the objective of minimizing the total system cost, which incorporates equipment operation and maintenance expenses, battery depreciation, penalties for renewable… More >

Hongsheng Su, Dan Li^*, Yuwei Du

Energy Engineering, DOI:10.32604/ee.2025.072397

Abstract When the three-phase grid-connected inverter system is in operation, there are problems of significant switching losses and power losses. At the same time, if the switching frequency is not fixed, it will lead to problems such as a high content of low-order harmonics in the current on the grid side. This paper takes the three-phase grid-connected inverter as the research object and proposes a solution. Establish a mathematical model for the inverter system and analyze the transformation relationships of relevant electrical quantities across different coordinate systems. First, the paper proposes an improved three-vector model predictive… More >

Huajie Zhang¹, Xiaopeng Li¹, Hanlin Xiao^2,*, Lifeng Xing², Wenyue Zhou¹

Energy Engineering, DOI:10.32604/ee.2026.071768

Abstract The integration of a high proportion of renewable energy introduces significant challenges for the adaptability of traditional fault nature identification methods. To address these challenges, this paper presents a novel fault nature identification method for renewable energy grid-connected interconnection lines, leveraging wavelet packet decomposition and voltage waveform time-frequency morphology comparison algorithms. First, the paper investigates the harmonic injection mechanism during non-full-phase operation following fault isolation in photovoltaic renewable energy systems, and examines the voltage characteristics of faulted phases in renewable energy scenarios. The analysis reveals that substantial differences exist in both the time and frequency… More >

Long Yu^1,*, Xianghua Pan², Rui Sun¹, Yuan Li³, Wenjia Hao⁴

Energy Engineering, DOI:10.32604/ee.2025.070023

Abstract Distribution transformers play a vital role in power distribution systems, and their reliable operation is crucial for grid stability. This study presents a simulation-based framework for active fault diagnosis and early warning of distribution transformers, integrating Sample Ensemble Learning (SEL) with a Self-Optimizing Support Vector Machine (SO-SVM). The SEL technique enhances data diversity and mitigates class imbalance, while SO-SVM adaptively tunes its hyperparameters to improve classification accuracy. A comprehensive transformer model was developed in MATLAB/Simulink to simulate diverse fault scenarios, including inter-turn winding faults, core saturation, and thermal aging. Feature vectors were extracted from voltage,… More >

Polina A. Tretyakova^*, Alexey P. Belkin, Alexander A. Rumyantsev, Anna A. Menshikova

Energy Engineering, DOI:10.32604/ee.2025.075393

Abstract Limited adoption of solar energy in the Northwestern region of Russia is associated with insufficient data on annual solar radiation indicators and on the potential of solar collectors for water heating. The study aims to evaluate the potential of solar water heating for domestic use in Northwestern Russia, using Tyumen city as the case. In this region, the number of cloudy days ranges from 5% to 50%, with cloud cover increasing in winter. New data on the total solar radiation, availability duration, and cloud cover have been collected. Solar irradiance could reach 900 MJ/m² during summer… More >

Mirna Omar^1,*, Sarah Omar¹, Kamaruzzaman Sopian^1,2, Taib Iskandar Mohamad¹

Energy Engineering, DOI:10.32604/ee.2026.072583

Abstract Photoreforming is an emerging photocatalytic process that converts organic waste into hydrogen H₂ using solar energy, offering a dual solution for waste valorization and sustainable fuel production. This review comprehensively examines the fundamental mechanisms of photoreforming, emphasizing the critical role of photocatalyst design in optimizing hydrogen evolution. Key criteria for effective photocatalysts including suitable band edge positions, broad spectrum solar absorption, and photostability are systematically analyzed alongside advances in heterojunction engineering and defect modulation. The review further explores diverse waste-derived feedstocks, such as biomass: alcohols, saccharides, lignin and plastics: PET, PLA, polyolefins, highlighting substrate, specific challenges More > Graphic Abstract

Zhen Pan¹, Lijuan Huang¹, Kaiwen Huang¹, Feipeng Huang¹, Bo Yang^2,*

Energy Engineering, DOI:10.32604/ee.2026.077000

Abstract With the global pursuit of carbon neutrality and the rapid development of marine renewable energy, offshore power transmission has become a key link in the integration of offshore power into onshore power grids. This paper summarizes the current advanced offshore transmission technologies, including high voltage alternating current transmission, high voltage direct current transmission, multi-terminal high voltage direct current transmission, hybrid high voltage direct current transmission, frequency division transmission, offshore overhead line transmission and energy storage transmission system. The application scenarios of various technologies are analyzed in detail: High voltage alternating current transmission is suitable for More >

He Wang, Yuyan Wang, Jing Bian^*, Huanan Yu

Energy Engineering, DOI:10.32604/ee.2026.076766

Abstract Addressing the challenges of peak shaving and curtailment caused by integrating a large amount of renewable energy into the grid, this paper proposes an optimized operation method for microgrid electricity-hydrogen hybrid energy storage (EH-HES), which considers electrolyzer arrays and an energy management strategy (EMS). Firstly, the time span of the energy-rich season and the energy-poor season is determined through time series decomposition, and a hydrogen energy storage (HES) operation mode based on seasonal typical scenarios is proposed. Secondly, the key equipment for EH-HES is modeled, including the hybrid electrolyzer arrays model that considers rotation strategy… More >

Xiaolan Li^1,2,*, Jinyu Shen^1,2, Jinhuang Liang^1,2, Yanting Wang^1,2

Energy Engineering, DOI:10.32604/ee.2026.076521

Abstract The intrinsic volatility and stochasticity of large-scale wind power generation pose significant challenges to grid stability. To address the limitations of conventional models in capturing strong non-stationarity, this study proposes a novel Multi-Stage Adaptive Forecasting Network (MSAF-Net). The framework features a hierarchical signal refinement strategy coupled with an intelligently optimized hybrid predictor. Initially, input redundancy is minimized via Pearson Correlation Coefficient (PCC) analysis to isolate significant meteorological variables. A two-phase decomposition-reconstruction mechanism is then implemented: the wind power series is first decomposed using Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN). To optimize the… More >

Naveen Guguloth¹, Bishwajit Dey², Fausto Pedro García Márquez^3,*, Prasenjit Dey¹, Isaac Segovia Ramírez⁴

Energy Engineering, DOI:10.32604/ee.2025.073971

Abstract The increasing integration of electric vehicle (EV) loads into power systems necessitates understanding their impact on stability. Small-magnitude perturbations, if persistent, can cause low-frequency oscillations, leading to synchronism loss and mechanical stress. This work analyzes the effect of voltage-dependent EV loads on this small-signal stability. The study models an EV load within a Single-Machine Infinite Bus (SMIB) system. It specifically evaluates the influence of EV charging through the DC link capacitor of a Unified Power Flow Controller (UPFC), a key device for damping oscillations. The system’s performance is compared to a modified version equipped with More >