1. Dynamic modeling and experimental validation of the photovoltaic/thermal systemKlemen Sredenšek, Eva Simonič, Klemen Deželak, Marko Bizjak, Niko Lukač, Sebastijan Seme, 2025, izvirni znanstveni članek Opis: The aim of this paper is to present a novel and comprehensive methodology for the dynamic modeling and experimental validation of a photovoltaic/thermal system. The dynamic model is divided into thermal and electrical subsystems, encompassing the photovoltaic/ thermal module and the thermal energy storage. The thermal subsystem of both the photovoltaic/thermal module and the thermal energy storage is described by a one-dimensional dynamic model of heat transfer mechanisms and optical losses, while the electrical subsystem is presented as an electrical equivalent circuit of double diode solar cell. Model validation was conducted on a modern experimental photovoltaic/thermal system over an extended operational period at a five-minute resolution, with validation days classified as sunny, cloudy, or overcast based on weather conditions, thereby demonstrating an applied approach. The results demonstrate the lowest deviation values reported to date, confirmed using six quantitative indicators. The added value of the proposed methodology, not previously addressed in the literature, lies in the following contributions: (i) comprehensive modeling of the entire photovoltaic/thermal system, (ii) accurate consideration of optical losses in the photovoltaic/thermal module, and (iii) long-term experimental validation. Overall, the proposed methodology provides a reliable and efficient framework for PV/T system design, optimization, and long-term performance assessment.
Ključne besede: photovoltaic/thermal system, thermal energy storage, dynamic modeling, experimental validation, heat transfer mechanism, temperature, electrical power
Objavljeno v DKUM: 10.11.2025; Ogledov: 0; Prenosov: 5
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2. 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, izvirni znanstveni članek Opis: 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.
Ključne besede: 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)
Objavljeno v DKUM: 06.11.2025; Ogledov: 0; Prenosov: 2
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3. Enhancing grid stability and low voltage ride through capability using type 2 fuzzy controlled dynamic voltage restorerCh. Sajan, P. Satish Kumar, Peter Virtič, 2024, izvirni znanstveni članek Opis: Introduction. The integration of Renewable Energy Sources (RESs), particularly Wind Energy Conversion Systems (WECS), is vital for reducing reliance on fossil fuels and addressing climate change. However, this transition poses challenges, including ensuring grid stability in the face of intermittent RESs. Compliance with grid codes is crucial, with a focus on Low Voltage Ride Through (LVRT) capability.
Problem. The intermittent nature of RESs, specifically in Permanent Magnet Synchronous Generator (PMSG) based WECS, presents challenges to grid stability during voltage dips.
Goal. To enhance voltage stability and LVRT capability in PMSG-based WECS by integrating a Dynamic Voltage Restorer (DVR) with an energy storage device. This involves regulating the input DC voltage to the DVR using a type 2 fuzzy controller, adapting intelligently to changing conditions.
Methodology. DVR, powered by an energy storage device, is strategically integrated with WECS. A type 2 fuzzy controller regulates the DC voltage to DVR. The rectified WECS output undergoes processing through an isolated flyback converter. A 31-level Cascaded H-Bridge Multilevel Inverter (CHBMLI) with PI control ensures high-quality AC output.
Results. The validation of developed system is executed using MATLAB/Simulink revealing a reduced Total Harmonic Distortion (THD) value of 1.8 %, ensuring significance in LVRT capability.
Originality. The strategic integration of DVR with PMSG-based WECS, addresses the LVRT challenges. The use of type 2 fuzzy controller for intelligent voltage regulation and a sophisticated multilevel inverter contributes to the uniqueness of proposed solution.
Practical value. The developed system provides benefits by ensuring reliable LVRT capability in PMSG-based WECS with reduced THD of 1.8 % indicating improved grid compatibility. References 26, tables 5, figures 20.
Ključne besede: permanent magnet synchronous generator, wind energy conversion systems, low voltage ride through, type 2 fuzzy controller, isolated flyback converter, 31-level cascaded H-bridge multilevel inverter, PI controller
Objavljeno v DKUM: 06.11.2025; Ogledov: 0; Prenosov: 2
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4. Analysis of the Operational Reliability of Different Types of Switching Substations Using the Monte Carlo MethodFranjo Pranjić, Peter Virtič, 2024, izvirni znanstveni članek Opis: This study investigates the operational reliability of different types of switching substations within the context of power systems, employing the Monte Carlo method for analysis. The research focuses on evaluating the reliability of high-voltage substations, including single-busbar systems, double-busbar systems, and switchgears with a ring-type power supply. By conducting simulations and analyzing statistical data on device reliability, the study aims to identify the most reliable implementation of switching substations. The results are presented through graphical representations and comparative tables, highlighting the impact of factors such as the number of switching elements and their connection on operational reliability. The findings indicate that configurations with a greater number of busbars and a parallel connection of switching elements exhibit higher operational reliability. The study provides insights to inform decision-making in the construction of new switching substations, emphasizing the importance of stable operation within power systems.
Ključne besede: switchgear, switching devices, high voltage, operating reliability, unavailability, failure interval
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5. Analytical, numerical and experimental performance prediction of a model-sized wind turbineMatej Fike, Andrej Predin, Gorazd Hren, Marko Pezdevšek, 2024, izvirni znanstveni članek Opis: The present work focuses on the comparison of the capabilities of Blade Element Momentum Theory, with and without the high induction factor value model and Computational Fluid Dynamics modelling in relation to experimental measurements of the power coefficient for a model-sized horizontal axial wind turbine. Initially, an analytical investigation was performed to obtain the power coefficient curve. Furthermore, three-dimensional numerical simulations were performed, where a lot of effort was devoted to the preparation of a low y+ structured mesh. Analytical and numerical results of the power coefficient were compared with experimental results, which were obtained with our own conducted experiments in the wind tunnel. The most significant conclusions are that the classic BEM method deviates from measured data in the entire range of tip speed ratios, the BEM method with Spera correction predicts a significantly better agreement with experimental measurements compared to the classic BEM method, especially the part where the power coefficient decreases and finally that CFD computations can accurately predict the performance of wind turbines and compute the flow around an aerofoil of the blade.
Ključne besede: BEM method, CFD, measurements, wind turbine
Objavljeno v DKUM: 06.11.2025; Ogledov: 0; Prenosov: 3
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6. Cogging torque reduction techniques in axial flux permanent magnet machines : a reviewFranjo Pranjić, Peter Virtič, 2024, pregledni znanstveni članek Opis: Axial flux permanent magnet machines have garnered significant attention in recent years due to their numerous advantages in various applications, including electric vehicles, wind turbines, and robotics. However, one of the critical challenges associated with these machines is the presence of cogging torque, which can hinder their efficiency and performance. This review article provides a comprehensive overview of the state-of-the-art techniques employed for cogging torque reduction in Axial Flux Permanent Magnet Machines. Different techniques are described, encompassing geometric optimization, magnet placement, and skewing methods. Firstly, the significance of Axial Flux Permanent Magnet Machines is described, as well as the issue of the cogging torque. In the methods section, a review of the strategies for the reduction of cogging torque is described from various articles, and finally, in the discussion section, a list of actions is presented for cogging torque reduction for different topologies. The novelty of the study is that it combines strategies for cogging torque reduction in a single article.
Ključne besede: cogging torque, axial flux permanent magnet machines, geometric optimization, magnet placement strategies, skewing techniques
Objavljeno v DKUM: 06.11.2025; Ogledov: 0; Prenosov: 3
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8. Research on the modelling and analysis of the penetration of renewable sources and storage into electrical networksEva Simonič, Sebastijan Seme, Klemen Sredenšek, 2025, izvirni znanstveni članek Opis: To address the growing integration of renewable energy sources and storage systems into distribution networks, there is a need for effective tools that can assess the impact of these technologies on grid performance. This paper investigates the impact of integrating residential rooftop photovoltaic (PV) systems and battery energy storage systems (BESSs) into low-voltage (LV) distribution networks. A stochastic approach, using the Monte Carlo method, is applied to randomly place PV systems across the network, generating multiple scenarios for power flow simulations in MATLAB Simulink R2024b. The method incorporates real-world consumer load data and grid topology, representing a novel approach in simulating distribution network behaviour accurately. The novelty of this paper lies in its ability to combine stochastic PV placement with real-world load data, providing a more realistic representation of network conditions. The simulation results revealed that widespread PV deployment can lead to overvoltage issues, but the integration of BESSs alongside PV systems mitigates these problems significantly. The findings of this paper offer valuable insights for Distribution Network Operators, aiding in the development of strategies for optimal PV and BESS integration to enhance grid performance.
Ključne besede: photovoltaic system, battery energy storage system, low-voltage distribution network, Monte Carlo method, power flow
Objavljeno v DKUM: 03.11.2025; Ogledov: 0; Prenosov: 7
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9. Energetska skupnost s sončno elektrarnoManca Kerkoč, 2025, diplomsko delo Opis: V diplomskem delu je obravnavan koncept energetske skupnosti s sončno elektrarno kot trajnosten model samooskrbe, spodbujanja energetske neodvisnosti in zmanjševanja negativnih vplivov na okolje. Pojasnjeni so osnovni pojmi, vrste skupnosti, njihove prednosti in slabosti ter primeri iz Slovenije. Obravnavana je povezava med nihanjem borznih cen električne energije, finančnimi prihranki sončne elektrarne in pregled slovenske zakonodajne podlage energetskih skupnosti. V nadaljevanju so pojasnjeni okoljski, ekonomski in družbeni vidiki ter glavni izzivi skupnosti. Raziskovalni del zajema samooskrbno skupnost v Budanjah s podrobno analizo prihrankov izbranega člana skupnosti in primerjavo glede na pričakovane prihranke.
Ključne besede: energetska skupnost, sončna elektrarna, samooskrba, obnovljivi viri energije, ekonomska upravičenost
Objavljeno v DKUM: 01.10.2025; Ogledov: 0; Prenosov: 33
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10. Pregled prevzema in oddaje električne energije v elektroenergetskem sistemu Slovenije od leta 2019 do leta 2023Luka Gruden, 2025, magistrsko delo Opis: Namen magistrskega dela je predstaviti analizo pregleda prevzema in oddaje električne energije v elektroenergetskem sistemu Slovenije od leta 2019 do leta 2023. Na začetku smo na kratko predstavili elektroenergetski sistem Slovenije, glavne proizvajalce, njihove proizvodne zmogljivosti ter investicijske načrte posameznih proizvajalcev. V glavnem delu smo podrobno analizirali proizvodnjo in porabo električne energije v elektroenergetskem sistemu Slovenije med letoma 2019 in 2023 ter trende proizvodnje in porabe. Prikazali smo porast vključevanja in proizvodnje električne energije iz obnovljivih virov ter doseganje ciljev na osnovi nacionalnega energetskega in podnebnega načrta NEPN. Predstavili smo tudi bilanco moči v opazovanih letih. V
zaključnem delu smo predstavili vpogled v prihodnost elektroenergetskega sistema Slovenije do leta 2050 ter cilje za povečanje kapacitet proizvodnih enot v okviru doseganja nacionalnih in evropskih ciljev na področju energetike in podnebja.
Ključne besede: elektroenergetski sistem Slovenije, prevzem in predaja električne energije, energetska samozadostnost, analiza, proizvodnja električne energije, fotovoltaična energija, poraba
Objavljeno v DKUM: 01.10.2025; Ogledov: 0; Prenosov: 16
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