1. Performance Enhancement of Grid Connected Multilevel Inverter Based Wind Energy Conversion System with LVRT Capability Using Optimized Type 2 ANFIS Based DVRCh. Sajan, P. Satish Kumar, Peter Virtič, 2024, original scientific article Abstract: A Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System (WECS) holds significant importance in the realm of Renewable Energy Sources (RES) for several reasons. The permanent magnets in the generator eliminate the need for a separate excitation system, leading to improved efficiency in power conversion. This makes PMSG-based WECS an effective and reliable source of wind energy electricity. The motivation behind the proposed conceptual framework stems from the need to overcome the limitations related to the integration of RES into the power grid, specifically focusing on voltage stability and Low Voltage Ride Through (LVRT) capability of PMSG based WECS. A Dynamic Voltage Restorer (DVR), empowered by an energy storage device, is used to mitigate voltage fluctuations and disturbances. The input DC voltage to the DVR is intricately regulated by a Type 2 Adaptive Neuro Fuzzy Inference System (ANFIS) Controller optimized using the Seagull algorithm, exhibiting intelligent adaptability to dynamic conditions. The rectified output from the WECS transforms an Isolated Flyback converter. Subsequently, a 31-Level Cascaded H-Bridge Multilevel Inverter (CHBMLI) along with a Proportional-Integral (PI) controller aids in generating high-quality AC output. By addressing challenges related to voltage stability and the ability to ride through low-voltage conditions, the proposed work contributes to enhanced grid stability. The use of advanced control techniques, including the Type 2 ANFIS Controller optimized by the Seagull algorithm, adds a layer of intelligent adaptability to changing environmental and grid conditions. A lower Total Harmonic Distortion (THD) Value of 1.29% is shown during the validation of the created system utilizing MATLAB/Simulink, assuring significant LVRT capabilities.
Keywords: Permanent Magnet Synchronous Generator (PMSG), Wind Energy Conversion System (WECS), Renewable Energy Sources (RES), Low Voltage Ride Through (LVRT), Type 2 Adaptive Neuro Fuzzy Inference System, 31-Level CHBMLI, Proportional-Integral (PI)
Published in DKUM: 06.11.2025; Views: 0; Downloads: 1
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2. Environmental pollution and economic activity : estimating the environmental Kuznets curve for a panel of countries worldwideDarja Boršič, Petar Todorčević, Nejc Fir, 2025, original scientific article Abstract: This paper aims to assess the impact of certain economic factors on pollution for selected 112 countries worldwide. Due to data availability, carbon dioxide emissions in tonnes per capita were chosen as the dependent variable measuring pollution. Based on panel data and generalized moments method, the relationship between economic activity and environmental pollution was estimated. The results show that in the whole sample, as well as for two subsamples of developed and undeveloped countries, carbon dioxide emissions are statistically significantly affected by gross domestic product per capita, energy intensity and renewable energy consumption. The linear effect of economic activity positively effects the pollution, while the quadratic relationship is negative. Thus, the validity of inverted-U curve of the environmental Kuznets curve has been demonstrated. The estimated effect of economic activity measured by gross domestic product per capita on pollution does not differ in developed and undeveloped countries.
Keywords: environmental Kuznets curve, carbon dioxide emissions, renewable energy, industrialisation, urbanisation, economic development, cross-section analysis
Published in DKUM: 21.10.2025; Views: 0; Downloads: 2
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3. Assessment of harmonic distortion in school buildings equipped with grid-connected PV systemsFranjo Pranjić, 2025, professional article Abstract: The integration of photovoltaic systems into power grids can impact power quality, particularly concerning voltage and current harmonics. This study investigates the power quality of a photovoltaic system integrated into the electrical system of an educational facility, focusing on harmonic distortion in both voltage and current. Comprehensive measurements were conducted across three phases and analysed according to the EN 50160 and IEEE 519 Standards. The results demonstrated that, while the voltage quality meets EN 50160 requirements consistently, indicating stable voltage levels, the current measurements revealed significant harmonic distortion. Notably, Phase 2 exhibited Total Harmonic Distortion values substantially above the acceptable limits, with Phase 1 and Phase 3 also showing elevated Total Harmonic Distortion. To address these issues, the study recommends the implementation of advanced harmonic filters and optimisation of inverter technologies. These measures are crucial for enhancing power quality, and ensuring compliance with the industry Standards in high photovoltaic penetration scenarios.
Keywords: power quality analysis, grid-connected PV systems, EN 50160 standard, IEEE 519 Standard, IEC 61000 standard, voltage harmonics, current harmonics, harmonic distortion, renewable energy integration, compliance assessment
Published in DKUM: 01.10.2025; Views: 0; Downloads: 1
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4. Biomass gasification potential for Slovenia’s green transition : e-mobilityNeja Hadžiselimović, Tjaž Hadžiselimović, 2025, original scientific article Abstract: In 2024, approximately fifty percent of the total kilometersdriven by passenger vehicles in Slovenia were attributed to diesel-powered automobiles, underscoring the persistent dependence of the transportation sector on fossil fuels, which are major contributors to greenhouse gas emissions and global warming. Research further substantiates that the transportation sector constitutes the nation's predominant source of greenhouse gas emissions. In this context, e-mobility emerges as a key strategy for Slovenia’s green transition in transportation. Additionally, biomassgasification represents a sustainable and environmentally friendly energy pathway that could support the country in achieving its environmental targets, while promoting the principles of the circular economy.
Keywords: green transition, renewable energy, forest biomass, biomass gasification, e-mobility
Published in DKUM: 29.09.2025; Views: 0; Downloads: 3
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5. From waste to hydrogen: utilizing waste as feedstock or catalysts for hydrogen generationDavid Tian Hren, Andreja Nemet, Danijela Urbancl, 2025, review article Abstract: With the world facing the twin pressures of a warming climate and an ever-increasing amount of waste, it is becoming increasingly clear that we need to rethink the way we generate energy and use materials. Despite growing awareness, our energy systems are still largely dependent on fossil fuels and characterized by a linear ‘take-make-dispose’ model. This leaves us vulnerable to supply disruptions, rising greenhouse gas emissions, and the depletion of critical raw materials. Hydrogen is emerging as a potential carbon-free energy vector that can overcome both challenges if it is produced sustainably from renewable sources. This study reviews hydrogen production from a circular economy perspective, considering industrial, agricultural, and municipal solid waste as a resource rather than a burden. The focus is on the reuse of waste as a catalyst or catalyst support for hydrogen production. Firstly, the role of hydrogen as a new energy carrier is explored along with possible routes of waste valorization in the process of hydrogen production. This is followed by an analysis of where and how catalysts from waste can be utilized within various hydrogen production processes, namely those based on using fossil fuels as a source, biomass as a source, and electrocatalytic applications.
Keywords: hydrogen production, waste-derived catalysts, renewable energy, biomass conversion
Published in DKUM: 25.09.2025; Views: 0; Downloads: 6
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6. The impact of wind power plant size on economic viability at the Ojstrica locationAndraž Roger, Matej Fike, 2025, professional article Abstract: Wind energy in Slovenia has not yet achieved a significant share in the energy resource mix, due primarily to the limited number of suitable locations and opposition from local communities. Nevertheless, interest in wind power plants is increasing, as they represent significant potential for utilising renewable energy sources. The paper analyses the economic viability of wind farm installation and electricity production at the proposed Ojstrica site in the Dravograd Municipality. Two scenarios were considered, involving wind turbines with capacities of 3.5 MW and 7 MW. Based on wind speed data, turbine power curves, and an electricity selling price of 75 EUR/MWh, the study calculated the maximum investment costs for each turbine type to ensure economic viability under the condition of a net present value (NPV) equal to zero. The results show that the maximum allowable investment is 5.99 million EUR for the 3.5 MW turbine and 15.60 million EUR for the 7 MW turbine.
Keywords: Ojstrica, wind turbines, economic viability, renewable energy, net present value
Published in DKUM: 16.06.2025; Views: 0; Downloads: 10
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7. The relationship between oil prices and stock prices of the European renewable energy companies : a vector autoregressive analysisEnis Slatina, Lejla Lazović-Pita, Ademir Abdić, Adem Abdić, 2023, original scientific article Abstract: This article aims to examine the potential relationship between Brent crude
oil futures prices and the index of the European renewable energy companies.
After the overview of the European legislation and the most recent literature
review on the topic, the article deploys a method of the Vector Autoregressive
Model (VAR). The analysis includes weekly data over eight years (2015-
2022). Our results indicate a positive correlation between Brent crude oil
futures prices and the value of the European Renewable Energy Total Return
(ERIX) index. The estimated bivariate VAR model indicates a statistically
significant relationship, meaning that past values of the ERIX Index may be
used to predict future Brent crude oil prices in the long run. Considering the
most recent systemic disturbance in the world’s commodity market, future
research should consider longer time series and possible relationships of
other macroeconomic factors.
Keywords: renewable energy, Brent crude oil, futures prices, ERIX index, VAR
Published in DKUM: 28.05.2025; Views: 0; Downloads: 2
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8. A multi-level approach to circular economy progress : linking national targets with corporate implementationJan Drofenik, Tine Seljak, Zorka Novak-Pintarič, 2025, original scientific article Abstract: An integrated top-down methodology for assessing and promoting progress towards a circular economy at macro (national) and micro (company) levels is presented. It is based on the MICRON (MIcroCirculaR ecOnomy iNdex) framework developed by Baratsas et al. (2022) for companies. In this paper, it has been extended to enable a consistent assessment for companies and countries. The methodology facilitates the analysis of key categories: energy, emissions, water, materials, and waste. A quantitative analysis of circularity, including a sensitivity analysis, is conducted at the macro level, identifying critical areas and the most influential factors for the circular economy. Based on this analysis, existing national strategies are evaluated, and implementation plans with specific measures are developed. This is followed by micro-level implementation, which involves techno-economic assessment of circular projects. Using this methodology, coordinated improvements in circularity are achieved at all levels. The methodology was tested in Slovenia, where the national circularity index revealed stable performance over five years, averaging slightly above 50 points out of 100. Analysis identified significant improvement potential in areas such as energy and emissions, aligning with the country's focus on decarbonization and energy efficiency in its climate strategies. At the company level, circularity assessments highlighted critical challenges in renewable energy use and overall energy efficiency. The proposed measures showed potential for significantly improving circularity and reducing emissions, while the results provided valuable insights into the economic feasibility of these transitions.
Keywords: circular economy, integrated assessment framework, micro level, energy transition, renewable energy
Published in DKUM: 10.02.2025; Views: 0; Downloads: 6
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9. Modeling and optimization of anaerobic digestion technology : current status and future outlookTina Kegl, Eloisa Torres Jiménez, Breda Kegl, Anita Kovač Kralj, Marko Kegl, 2025, review article Keywords: renewable energy, anaerobic digestion, biogas plant, mathematical models, optimization algorithms, products utilization
Published in DKUM: 31.01.2025; Views: 0; Downloads: 15
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10. Energy flexibility in aluminium smelting : a long-term feasibility study based on the prospects of electricity load and photovoltaic productionMarko Bizjak, Niko Uremović, Domen Mongus, Primož Sukič, Gorazd Štumberger, Haris Salihagić Hrenko, Dragan Mikša, Stanislav Kores, Niko Lukač, 2024, original scientific article Keywords: energy flexibility, aluminium smelting, renewable energy, virtual battery, solar production
Published in DKUM: 17.12.2024; Views: 0; Downloads: 21
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