Inverter-Based Power Flow Control of a Small-Scale Grid-Connected Doubly-Fed Induction Generator in Wind Energy Conversion Systems Under Variable Wind Speed Conditions
Milkias Berhanu Tuka(1.2), Anatoli Wellhöfer(3)
1. Alexander von Humboldt Foundation Postdoctoral Research Fellowships, Programme,Technical University of Applied Sciences Würzburg-Schweinfurt (THWS). Schweinfurt. Germany
2. Addis Ababa Science and Technology University. Addis Ababa. Ethiopia
3. Technical University of Applied Sciences Würzburg-Schweinfurt (THWS). Schweinfurt. Germany

Abstract

Inverters are critical components in wind turbine-based energy conversion systems, serving essential roles in control and grid synchronization under dynamic conditions. This paper presents an inverter-based power flow control using PI controller with an anti-windup mechanism for a small-sized 1 kW Doubly-Fed Induction Generator (DFIG), addressing a gap in the literature where the dynamic behavior of such systems is often insufficiently described. The control strategy is integrated with a Maximum Power Point Tracking (MPPT) algorithm. .... READ MORE

The Integration of a Photovoltaic/Thermal System into a District Heating System
K. Sredenšek(1,2), J. Počivalnik(1), D. Kuhar(1), B. Stergar(1), E. Simonič(1), G. Štumberger(2), S. Seme(1,2)
1. Faculty of Energy Technology, University of Maribor. Slovenia
2 Faculty of Electrical Engineering and Computer Science, University of Maribor. Slovenia

Abstract

District heating systems are increasingly transitioning toward low-carbon and renewable energy sources in response to climate and energy policy objectives. Among emerging technologies, photovoltaic/thermal systems represent a promising solution by enabling the simultaneous production of electrical and thermal energy. This paper investigates the performance and economic feasibility of a photovoltaic/thermal system integrated with a heat pump as a renewable heat source for low-temperature district heating applications..... READ MORE

Economic Viability of Photovoltaic and Battery Storage Systems for Residential Electric Vehicle Charging in Slovenia
D. Kuhar(1), J. Počivalnik(1), E. Simonič(1), B. Stergar(1), S. Seme(1,2),  K. Sredenšek(1,2)
1. Faculty of Energy Technology, University of Maribor. Slovenia
2. Faculty of Electrical Engineering and Computer Science, University of Maribor. Slovenia

Abstract

This paper analyzes the payback periods of investments in photovoltaic and energy storage systems under different electric vehicle charging scenarios in Slovenia, accounting for electricity cost structures. Based on fifteen-minute residential household electricity consumption data, two driving scenarios were evaluated: a high-mileage case with an annual driving distance of approximately 58,000 km and a low-mileage case of approximately 15,000 km. Electrical energy costs were calculated based on the currently applicable electricity billing methodology in Slovenia..... READ MORE

Receding Horizon Optimization of Residential Photovoltaic and Battery Storage Systems using Differential Evolution
J. Počivalnik(1), D. Kuhar(1), E. Simonič(1), B. Stergar(1), S. Seme(1,2), K. Sredenšek (1,2)
1. Faculty of Energy Technology, University of Maribor. Slovenia
2. Faculty of Electrical Engineering and Computer Science, University of Maribor. Slovenia

Abstract

The paper examines the use of receding horizon optimization combined with differential evolution for the control of a residential battery storage system integrated with a photovoltaic system. The objective is to reduce grid power peaks and overall electrical energy exchange with the grid by optimizing the operating strategy of the battery storage system. The proposed approach is evaluated using real household electrical energy consumption data and modeled photovoltaic system production with a 15-minute time resolution.  .... READ MORE

Stand-Alone Solar Systems: an Educational Platform for Undergraduate and Graduate students
V. Boitier(1), J. Dedieu(2), H. Martinetti (2)
1. LAAS-CNRS, Université de Toulouse, CNRS. Toulouse, France
2. Université de Toulouse. France

Abstract

This work features two off-grid photovoltaic systems, each with a power of 400 Wp, equipped with a battery storage system (24V 110Ah). One is designed to power 24 V DC loads, the other 230 V AC loads. Both installations are fitted with monitoring equipment (measuring electrical parameters, irradiance and temperatures) and the measurements are recorded in a database. These installations offer numerous opportunities for students from undergraduate to postgraduate level. .... READ MORE

Social Impact in the Optimization of Logistics Chains for Waste-Derived Biofuels: Comparison between Mono-and Multi-Objective Approaches in Colombia
Simón Herrera Ramírez,  Juan David Parra Cantor, Laura Andrea Carmona Morales, Raúl Valencia, Carlos A. Bustamante, Whady F. Flórez Escobar, Hader V. Martínez Tejada, Oscar Vasco-Echeverry
Optimization Research Group / Grupo GINUMA. Universidad Pontificia Bolivariana, Mechanical Engineering Program. Medellín. Colombia

Abstract

The transition toward a sustainable energy matrix and the efficient management of municipal solid waste (MSW) represent critical challenges in Colombia. This study optimizes the supply chain for the production of Refuse‑Derived Fuel (RDF) by comparing mono‑objective and multi‑objective approaches. A linear programming model is formulated that integrates four non‑commensurable objective functions: maximization of material flow, maximization of job creation (social impact), minimization of operating costs, and minimization of CO2 emissions.  .... READ MORE

Smart Charging of Urban Electric Bus Fleets Using Proximal Policy Optimization
A. Martínez (1), M. Alonso(1), H. Amaris(1), M. Cordeiro-Costas(2)
1. Department of Electrical Engineering. Universidad Carlos III de Madrid. Spain
2. CINTECX, Universidade de Vigo. Spain

Abstract

The large-scale deployment of electric buses (e-buses) requires intelligent charging hubs capable of ensuring cost-effective operation while maintaining fleet availability and preventing grid congestion. This paper presents a reinforcement learning–based energy management system for an urban e-bus logistics depot centre operating under technical and economic constraints, including uncertainty in battery state of charge and operational schedules. The charging problem is formulated as a Markov Decision Process and solved using Proximal Policy Optimization (PPO). .... READ MORE

ANN and MRAS based Speed Observer for Sensorless Control of Induction Motor Drive
S. Damkhi
Department of Electrical Engineering. Batna University. Algeria

Abstract

The Model Reference Adaptive System (MRAS) is indeed the most widely used strategy for speed estimation in
sensorless induction motor drives, thanks to its simplicity and satisfactory performance across a wide speed range. However, this technique has limitations: it is not optimal in medium- and high-speed regions and remains highly sensitive to variations in motor parameters.  .... READ MORE

Grid Resilience under high shares of Non‑Synchronous Generation: Insights from the 2025 Iberian Peninsula Blackout
S. Martín-Arroyo(1), M. García-Gracia(1), J.A. Cebollero(1), Á. Llamazares(1),  O. Anaya-Lara(2)
1. Department of Electrical Engineering. EINA, Zaragoza University. Spain
2. Department of Electronic and Electrical Engineering. Faculty of Engineering. University of Strathclyde, Glasgow. UK

Abstract

This paper investigates grid resilience in powersystems with high shares of non‑synchronous generation, using the 28 April 2025 Iberian Peninsula disturbance as a real‑world case study. The objective is to characterize the dynamic mechanisms governing instability propagation under structurally low‑inertia conditions. The study integrates high‑resolution measurement analysis, dynamic event reconstruction, and a layered root‑cause framework that distinguishes the initiating network disturbance from subsequent amplification processes. .... READ MORE

Control of an Islanded PV–Battery–PEM Electrolyzer Microgrid for Green Hydrogen Production
A. Llamazares, S. Martín-Arroyo, J.A. Cebollero, M. García-Gracia
Department of Electrical Engineering. EINA, Zaragoza University. Spain

Abstract

This paper presents the design and control of an islanded PV–battery–PEM electrolyser microgrid for green hydrogen production. The system integrates a PV plant, a lithium-ion BESS, and a 425 kW PEM electrolyser. A hierarchical control strategy is proposed, combining local converter control, DC-bus voltage regulation and a supervisory layer including cloud classification, fault handling and maximum-power operation modes..... READ MORE

Optimal Sizing of Photovoltaic System and Battery Storage in Self-Consumption Applications under Contemporary Regulatory Conditions
S. Seme(1,2), J. Počivalnik(1), D. Kuhar(1), B. Stergar(1), E. Simonič(1), K. Sredenšek(1,2)
1. Faculty of Energy Technology, University of Maribor. Krško. Slovenia
2 Faculty of Electrical Engineering and Computer Science, University of Maribor. Slovenia

Abstract

Photovoltaic systems integrated with battery storage are increasingly implemented within self-consumption schemes. Nevertheless, system sizing is frequently based on installed capacity limits rather than on a comprehensive techno-economic assessment of long-term performance. This paper investigates the optimal sizing of photovoltaic and battery storage systems for a small industrial consumer operating under current regulatory conditions in Slovenia, where battery storage integration is mandatory due to low-voltage network constraints. .... READ MORE

Where to Run the EMS Planner: Practical Cloud–Edge Placement for Two-Level Hierarchical EMS in Microgrids
G. Fernández(1), R. Estudillo(1), I. Sanz(1), J.F. Sanz-Osorio(2), L. Elorza-Uriarte(3)
1. Department of Electrical Systems, CIRCE Technology Centre, Zaragoza. Spain
2. Instituto Universitario de Investigación Mixto ENERGAIA (Universidad de Zaragoza—Fundación CIRCE). Spain
3. Energy Storage System unit, CIDETEC (BRTA). Donostia-San Sebastián. Spain

Abstract

The increasing penetration of distributed energy resources in microgrids is driving the adoption of Energy Management Systems (EMS) capable of coordinating generation, storage and flexible loads while meeting operational constraints. Two-level hierarchical EMS architectures, typically combining an upper-layer planner (rolling-horizon scheduling) with a lower-layer real-time controller, are a practical approach to cope with forecast uncertainty and fast dynamics.  .... READ MORE

Thermal Aging Assessment of Photovoltaic Cable Insulation Using XRF Spectroscopy
B. Stergar(1), J. Počivalnik(1), D. Kuhar(1), E. Simonič(1), S. Seme(1,2), K. Sredenšek(1,2)
1. Faculty of Energy Technology, University of Maribor.  Krško. Slovenia
2 Faculty of Electrical Engineering and Computer Science, University of Maribor. Slovenia

Abstract

The increasing deployment of photovoltaic systems requires reliable cable infrastructure capable of withstanding long-term thermal and environmental stresses. Polymeric insulation materials used in photovoltaic cables are susceptible to thermal degradation, which can progressively deteriorate their mechanical and dielectric properties. A key degradation mechanism of polyvinyl chloride insulation is dehydrochlorination, which leads to chlorine loss and structural changes in the polymer matrix. .... READ MORE

Thermo–Energetic Modelling and Operational Load Limits of a Solar Dryer for Chestnuts
Nicole Leonardo, Freddy J. Rojas, Celso De-La-Cruz
Department of Engineering. Pontifical University Catholic of Peru. Perú

Abstract

This study presents a thermoenergetic evaluation of a solar drying system for chestnuts, operating with an initial moisture content of 47% and a final moisture content of 20%. The system consists of a 1 m³ drying chamber coupled to a solar collector with a thermal efficiency of 45%, evaluated with an average solar irradiance of 656 W/m² and an ambient temperature of 26 °C. .... READ MORE

Real‑World Energy Consumption Comparison Between a Diesel Vehicle and a Battery‑Electric Vehicle
M. Fike, A. Predin, A. Roger
Faculty of Energy Technology, University of Maribor. Slovenia

Abstract

This study presents a real‑world comparison of energy consumption between a battery‑electric vehicle (BEV), the Skoda Enyaq iV80, and a conventional internal combustion engine (ICE) vehicle, the Skoda Octavia 2.0 TDI. Both vehicles were driven over identical rural, suburban, and motorway routes to capture representative driving conditions, including uphill and downhill segments.  .... READ MORE

Laboratory Test Facility for Real-Time Thermal Rating Validation of Insulated Power Cables
S. Bustamante, M. Sotelo, M. Mañana, A. Arroyo, P. Benavente, E. Sainz-Ortiz, L. Vejo
Department of Electrical Engineering and Energy Engineering. E.T.S.I.I.T., Universidad de Cantabria, Santander. Spain

Abstract

This paper presents the design, construction, andcommissioning of a laboratory-scale pilot installation developed for the experimental validation of Real-Time Thermal Rating (RTTR) algorithms applied to insulated high-voltage power cables. The pilot is designed to provide high-resolution and reliable thermal measurements under controlled operating conditions. It combines point-wise temperature sensing using platinum resistance temperature detectors (Pt100 sensors) with Distributed Temperature Sensing (DTS) via optical fibres integrated within the cable. .... READ MORE

Making the traditional Home Smart
Péter Kádár
Óbuda University. KVK Dept. of Power Systems. Budapest. Hungary

Abstract

The forced PV generation sometimes produces surplusthat can’t be used. The Demand Side Management (DSM) has an important role in the balance realization of the load and generation in the power system. The small scale but large number household power management applications have reasonable effect on the national level power balance..... READ MORE

Assessment of the Guaranteed Origin of Electricity Used for Green Hydrogen Production in an Integrated Energy System
P. Lezhniuk(1,2), M. Belik(3), O. Rubanenko(1,2,3,4), I. Hunko(1,2)
1. Institute of Renewable Energy, Kyiv, Ukraine,
2. Department of electric station and system, Vinnytsia, Ukraine
3. Department of Electrical Power Engineering, University of West Bohemia in Pilsen. Czech Republic
4. Research and Innovation Centre for Electrical Engineering, University of West Bohemia, Plzen. Czech Republic

Abstract

The formation of integrated energy systems is a result of the decentralization of power generation, the expansion and increasing capacity of renewable energy sources, and the implementation of Smart Grid technologies. A distinctive feature of such systems is the integrated use of electricity, gas, and heat within a single infrastructure with intelligent control. In these systems, electricity generated by various types of power plants, including both renewable and conventional sources, is transmitted through a common network to consumers. .... READ MORE

The application of orthogonal vector theory to optimize the coordination between a 3-level inverter and a 2-level inverter
A. Muc
Department of Ship Automation. Gdynia Maritime University. Gdynia. Poland

Abstract

This article demonstrates the potential application of orthogonal vector theory to the design and control of complex systems with three-phase inverters. The paper presents the interaction of a three-level inverter with a two-level inverter using two control strategies. The obtained results are presented in the form of simulation studies. .... READ MORE

Role of External Grid Representations in Frequency Stability Studies of Power Systems with High Non-Synchronous Generation
I. Taczi, I. Vokony, G. M Peter
Department of Electric Power Engineering. Budapest University of Technology and Economics. Budapest. Hungary

Abstract

The transition toward power systems with high shares of non-synchronous generation has made the quality of dynamic system modeling increasingly important for credible stability assessment. Particular sensitivity arises at the boundaries of the study area, where the external grid is commonly represented by reduced or equivalent models rather than by a full dynamic description of the interconnected system. .... READ MORE

System Rigidity: A Comprehensive Approach to Enhancing Power System Stability
I. Vokony
Department of Electric Power Engineering. Budapest University of Technology and Economics. Budapest. Hungary

Abstract

The shift toward renewable-dominated power systems has significantly reduced inertia, challenging traditional stability metrics. This paper introduces system rigidity as a unified measure capturing frequency, voltage, and angle stability in low-inertia grids. A Rigidity Response Threshold (RRT) is defined as the maximum disturbance a system can endure without instability, derived using a Lyapunov-based framework. .... READ MORE

Enhanced Power Control for Voltage Support Strategy and Virtual Inertia Emulation for Distributed Battery Energy Storage System 
Ahmed Alharbi(1), Fahd Hariri(1), Yusuf Alturki(1,2)
1. Department of Electrical and Computer Engineering, Faculty of Engineering, King Abdulaziz University,  Jeddah, Saudi Arabia
2. Research and Innovation Center, King Abdulaziz University, Jeddah, Saudi Arabia

Abstract

In active distribution systems, the battery energy storage system (BESS) can support grid stability through coordinated active and reactive power control mechanisms. Therefore, this paper proposes a coordinated control scheme for BESS to voltage and frequency regulations under dynamic operating conditions.  For inertia emulation control, a coupling mechanism between the rate of change of frequency (RoCoF) combined with voltage magnitude and the required active power of grid is studied..... READ MORE

Current Control Capability of the AC/DC Converter
J. Iwaszkiewicz
Department of Ship Automation. Gdynia Maritime University. Gdynia. Poland

Abstract

This paper presents a comparative study of five hysteresis-based current-control algorithms applied to a grid-connected voltage source inverter operating as a bidirectional AC/DC converter. A linearized analytical model of the inverter–grid system, based on a current-generator representation of the intermediate DC circuit, is used to derive closed-form relations between phase currents, displacement angle and power factor.  .... READ MORE