Electrical Engineering & Electromechanics

Influence of zinc oxide nanoparticles on flashover voltage of unsaturated polyester resin-based composites for electrical insulators

M. Rihan, A. Ghazzaly, A. H. Fahmy, A. A. Ebnalwaled, L. S. Nasrat — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. Polyester-based composites are increasingly used in electrical applications for their insulation, mechanical, and thermal properties. Nanofillers have shown promise in enhancing the properties of polymer-based composites. Goal. This study aims to improve the flashover voltage of unsaturated polyester resin (UPR)-based composites by incorporating zinc oxide (ZnO) nanoparticles. Methodology. UPR/ZnO nanocomposites were prepared with various ZnO nanofiller ratios (0 %, 1 %, 3 %, 5 %, and 7 % by weight) with different sample lengths (0.5, 1.5, 2, and 2.5 cm). The flashover voltage was measured for the pure UPR sample and each composition of the studied filler ratios at various sample lengths. X-ray diffraction analysis was performed. A curve-fitting method was applied to estimate the flashover voltage of UPR/ZnO nanocomposites containing intermediate filler ratios between those experimentally tested. Results. Incorporation of ZnO nanofillers significantly enhanced the flashover voltage of polyester-based nanocomposites. The pure UPR sample exhibited the lowest flashover voltage, whereas the composite with 7 wt.% ZnO nanofiller demonstrated the highest. Notably, increasing the sample length further improved flashover voltage. Scientific novelty. This study examines the influence of ZnO nanoparticles on the flashover voltage of UPR-based composites. Practical value. The obtained findings can contribute to the development of polyester-based nanocomposite insulators with enhanced flashover voltage. References 26, tables 3, figures 6.

Efficient and reliable scheduling of power generating units in the unit commitment problem using the Tardigrade optimization algorithm

S. A. Alomari, A. Smerat, O. P. Malik, M. Dehghani, Z. Montazeri — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. The unit commitment (UC) problem is a critical operational task in power systems, involving the optimal scheduling of generating units while meeting demand, satisfying technical constraints, and minimizing operating costs. Due to its combinatorial nature, nonlinear characteristics, and numerous interdependent constraints, UC poses a highly complex optimization challenge. Metaheuristic algorithms have demonstrated strong potential in addressing such large-scale problems; however, many existing methods struggle to maintain a proper exploration–exploitation balance, limiting their performance in dynamic UC environments. Problem. Traditional metaheuristic algorithms often suffer from premature convergence, inadequate local refinement, or dependency on control parameters that require tuning. Such limitations reduce robustness and adaptability when dealing with UC’s intricate search landscape. Therefore, there is a need for a parameter-free, self-adaptive optimization algorithm capable of reliably solving UC with high efficiency and convergence stability. The goal of this study is to develop an efficient and reliable scheduling framework for power generating units in the UC problem by employing the tardigrade optimization algorithm (TOA) and to demonstrate its effectiveness compared with established optimization techniques. Methodology. TOA is inspired by the active and cryptobiotic survival behaviors of tardigrades. The exploration phase imitates active adaptive locomotion to broaden global search, while the exploitation phase abstracts cryptobiotic stability to refine solutions locally. These mechanisms are formulated through adaptive state-transition operators that adjust search behavior automatically without external parameters. TOA is applied to a 24-hour UC problem consisting of 10 generating units under realistic load and operational constraints. Its performance is benchmarked against 6 widely used metaheuristic algorithms. Results. The proposed TOA achieves the lowest total operating cost, exhibits strong convergence behavior, and demonstrates high consistency across independent runs, outperforming all comparative methods. The scientific novelty lies in introducing a biologically inspired, parameter-free, self-adaptive metaheuristic algorithm. Its practical value is validated through superior performance in UC scheduling, indicating strong potential for broader power system optimization tasks. References 21, tables 3, figures 3.

Comparative performance analysis of backstepping and sliding mode control for static synchronous compensators based on flying capacitor multicell converters

S. Belakehal, M. L. Srief — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. The integration of a static synchronous compensator (STATCOM) based on a flying capacitor multicell converter (FCMC) provides an effective solution for dynamic reactive power compensation and voltage quality improvement. The adoption of nonlinear control strategies, such as sliding mode control (SMC) and backstepping (BSC), enhances system robustness and ensures precise tracking of variables despite network nonlinearities and disturbances. Problem. Reactive, inductive or capacitive loads cause network imbalances leading to voltage sags, swells and fluctuations at the point of common coupling (PCC). These disturbances degrade power quality, reduce the power factor and place excessive stress on equipment. Moreover, high reactive power flow increases losses and decreases the overall system efficiency. Goal. This study compares the performance of SMC and BSC controllers applied to a STATCOM for PCC voltage regulation aiming to improve the power factor, effectively control reactive power and overcome the limitations of conventional controllers under network nonlinearities and voltage disturbances caused by reactive loads. Methodology. The SMC uses a sliding surface based on current errors to achieve fast and precise tracking even in the presence of disturbances. The BSC control employs Lyapunov functions to decompose the nonlinear system into controllable subsystems, ensuring overall stability. Both strategies are simulated on a 5-level flying capacitor multicell STATCOM using MATLAB/Simulink. Simulation results confirm the effectiveness of both controllers in maintaining the PCC voltage at its reference value with a very short response time (1 ms), even under reactive load variations. Precise reactive power control enables rapid compensation of fluctuations, improves the power factor and reduces harmonic distortion. The scientific novelty of this work lies in the comparative performance analysis of the nonlinear SMC and BSC controllers applied to a STATCOM based on a FCMC converter, considering network disturbances caused by reactive loads. Practical value. These nonlinear control strategies significantly enhance the stability, voltage quality, and power factor of low-voltage networks equipped with STATCOMs. References 36, tables 4, figures 18.

Optimizing residential energy usage patterns in smart grids using hybrid metaheuristic techniques

M. Kamal, M. F. Ullah, N. Anwar, A. I. Hussein — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. This study applies hybrid metaheuristic optimization techniques to intelligently schedule household loads, ensuring a balance between cost reduction, comfort and grid stability in smart homes. Problem. The growing gap between energy demand and supply leads to high electricity costs, increased appliance waiting times, a higher peak-to-average ratio (PAR) and reduced user comfort. Efficient management of residential energy consumption remains a major challenge for sustainable smart grid operation. Goal. This study aims to minimize electricity costs, reduce PAR and enhance user comfort by optimally scheduling household appliances and shifting loads from peak hours to off-peak hours. Methodology. A demand-side management approach is implemented using 5 metaheuristic optimization algorithms: harmony search algorithm (HSA), flower pollination algorithm (FPA), hybrid harmony flower pollination algorithm (HFPA), multiverse optimization algorithm (MVO) and cuckoo search algorithm (CSA). Real-time pricing is employed as the pricing model. MATLAB simulations were conducted for 10, 30 and 50 smart homes, each comprising 15 residential loads categorized as controllable or base appliances. Results. Simulation results demonstrate that the proposed HFPA consistently outperforms HSA, FPA, MVO and CSA across all tested scenarios, achieving notable reductions in electricity cost and PAR while minimizing appliance waiting times. Scientific novelty. The hybrid HFPA effectively combines the strengths of HSA and FPA, balancing exploration and exploitation to deliver superior performance in multi-objective optimization for home energy management systems. Practical value. The proposed HFPA achieved up to 19.86 % reduction in electricity cost and 81.03 % minimization in PAR, significantly enhancing user comfort and operational efficiency. The method can be further extended for integration with renewable energy sources and machine learning-based predictive control systems. References 32, tables 6, figures 5.

The methodology of multi objective design of active-passive shielding system for overhead power lines magnetic field in residential buildings space based on metaheuristic optimization method

Mon, 02 Mar 2026 00:00:00 +0200

Problem. Most studies of power frequency magnetic field reduced to safe level in in residential buildings located near overhead power lines carried out based on passive or active electromagnetic shielding, but there is no methodology for designing active-passive systems that include active and solid or multi-circuit passive shields. The goal of the work is to develop the methodology of multi objective design of active-passive electromagnetic shielding system, consisting of active and solid self or multi-circuit passive parts to improve shielding efficiency of initial magnetic field in residential building edges generated by overhead power lines to sanitary standards level. This goal proposed to achieve based on metaheuristic optimization method Methodology. Multi objective design methodology of active-passive shielding system based on solution of the geometric inverse problem of magnetostatics for the resulting magnetic field generated by the transmission line wires, compensation windings of the active shielding system and a passive shield in the form of a solid or multi-loop shield. The geometric forward problem is solved based on solutions of Maxwell’s equation for magnetic field three-dimensional model using the COMSOL Multiphysics software. The solution of the geometric inverse problem of magnetostatics is formulated as a minimax vector problem of nonlinear programming. The solution of the minimax vector problem of nonlinear programming is calculated based on the metaeristic optimization algorithm from Pareto optimal solutions taking into account binary preference relations. Results. During combined active and solid or multi-circuit passive shielding system design spatial arrangement coordinates of solid or multi-loop passive shield and compensating windings, as well as windings currents and phases of active shield calculated. New scientific results are theoretical and experimental studies of a designed combined active and of solid or multi-circuit passive shielding system efficiency for magnetic field created by overhead power lines. Scientific novelty. For the first time multi objective design methodology for combined active and solid or multi-circuit passive shielding system taking into account original field shielding effectiveness decrease in residential building edges for more effective reduction of industrial frequency magnetic field created by overhead power lines developed. Practical value. Practical recommendations for the reasonable choice of the coordinates of the spatial arrangement of compensation windings of the active shielding system and a passive shield in the form of a solid or multi-loop shield, as well as the currents and phases in the compensation windings, parameters of regulators of the open and closed controls of the two degrees of freedom active shielding system and parameters of positions of magnetic field sensors of the active shielding system for magnetic field generated by overhead power lines in residential building space are given. The possibility of reducing the initial magnetic field induction to the sanitary standards level shown. References 48, figures 11.

The use of shape memory alloys in fuses for the protection of electrical installations

V. V. Kozyrskyi, T. Nurek, J. Sloma, V. Ya. Bunko, M. V. Goncharuk — Mon, 02 Mar 2026 00:00:00 +0200

Problem. The degree of damage to electrical installations during short circuits depends on the response time of the protection. An effective way to enhance the current-limiting effect in electrical fuses (reducing their response time) may be the use of shape memory alloy (SMA) elements. However, this requires careful study and research. The goal of the work is to establish the patterns of strengthening the current-limiting effect of a fuse (reducing the response time) when using thermosensitive elements made of shape memory alloys. The achievement of this goal is based on the analysis of experimental studies conducted by the authors and mathematical models of the characteristics of a fuse containing an SMA element. Methodology. The article presents mathematical modelling of the parameters and characteristics of fuses with thermomechanical destruction of the fuse element, as well as a thermophysical model of a fuse with a thermosensitive SMA element. The article presents the results of experimental studies of a traditional fuse and a fuse equipped with a thermosensitive SMA element. For each current, the response time of the modified fuse was shorter than that of the traditional fuse. The use of a thermosensitive element reduced the response time by more than 20 times for a current of 10 A and approximately 10 times (from 0.257 s to 0.0244 s) for a current of 20 A. For the highest tested current (90 A), the fuse response time was half that of a traditional fuse. The article also presents the results of calculations of fuse characteristics using a mathematical model and a comparison with the results of experimental studies. Scientific novelty. The developed mathematical models of the characteristics of electrical fuses containing SMA elements made it possible for the first time to substantiate the interrelationships between the parameters (geometric dimensions and characteristics of SMA elements, fuse links) with current loads of electrical installations. The practical value of the work lies in the proposed use of thermosensitive elements made of functional materials to increase the current-limiting effect of electrical fuses for protecting electrical installations during short circuits. References 19, tables 2, figures 7.

Mitigation of cogging torque in surface permanent magnet brushless DC motor using slot opening shift

A. N. Patel, T. H. Panchal — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. Cogging torque deteriorates the torque quality of surface permanent magnet brushless DC (PMBLDC) motors. Problem. Reducing cogging torque is indispensable for performance upgradation of PMBLDC motors; hence, it is an important issue for motor designers. Goal. This paper presents a slot opening shift approach to reduce the cogging torque of radial flux surface PMBLDC motors. Methodology. A 200 W, 1000 rpm radial flux surface PMBLDC motor is first designed based on different assumed design variables and is treated as a reference model. The parallel stator teeth are uniformly distributed along the stator periphery, and the slot opening is considered in the middle position in the reference design. The cogging torque of the reference design is obtained from simulation and electromagnetic analysis. Results. A series of finite element simulations are performed to examine the impact of design upgradation on the cogging torque of the surface PMBLDC motor. It is observed that the peak-to-peak cogging torque is reduced by 44.5 %. Scientific novelty. The design is enhanced by applying slot opening shift to stator slots. The slot opening is shifted in an anticlockwise direction, and subsequently, the cogging torque waveform is determined for the upgraded motor from finite element modelling and analysis. Practical value. Research has revealed that this technique is effective in reducing cogging torque, and it can also be applied to other topologies of permanent magnet motors. References 23, tables 2, figures 12.

Highly accurate approximation for sheath currents in high-voltage three-phase cable line

O. Tkachenko, U. Pyrohova, V. Grinchenko — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. This study focuses on sheath currents in high-voltage single-core XLPE-insulated power cables with solid bonding. The analysis covers flat and trefoil three-phase cable lines. Sheath current calculation is essential for evaluating thermal conditions, losses, and overall cable performance. Problem. The regulatory documents of the Ministry of Energy of Ukraine provide formulas for sheath currents. We examine them by comparing with verified analytical solutions and find significant discrepancies in a wide range of typical parameters of high-voltage three-phase cable line. So the formulas in the current regulatory document have a narrow range of applicability, and the engineering calculations based on them may lead to significant inaccuracies and incorrect decisions. Goal. The paper aims to develop novel formulas for the RMS values of sheath currents in high-voltage three-phase cable lines with flat and trefoil arrangements of power cables, ensuring the accuracy required for engineering calculations across a wide range of cable line parameters. Methodology. This study is grounded on the previously developed and experimentally verified analytical model and corresponding formulas for calculating sheath currents and cable line magnetic field. These verified formulas for sheath currents are too cumbersome, so an approximation technique is used to find compact ones. Results. A novel approximation for sheath current in the flat cable line is developed. The discrepancy between the approximation and the verified formulas is within 5 %. Additionally, a new form of the formula for sheath current in the trefoil cable line is proposed. Scientific novelty. To perform the approximation, an original quality index is proposed. It is derived from the heat output of metal sheaths of cables. Practical value. The developed approximation for sheath current can be directly applied to the design of high-voltage cable lines, the analysis of the operating modes, and the control of the compliance of existing cable lines with actual operating conditions. References 20, table 1, figures 4.

Intelligent unified power quality conditioner based photovoltaic to improve grid reliability and mitigate power quality issues

I. I. Alnaib, A. N. Alsammak — Mon, 02 Mar 2026 00:00:00 +0200

Problem. Electrical distribution networks are plagued by power quality problems, which have a negative impact on sensitive electrical loads. These problems include reactive current, low power factor on the load side, and voltage harmonics, voltage sags and voltage swells on the grid voltage side. To address these issues, a unified power quality conditioner (UPQC) that combines shunt and series compensators is suggested. The goal of the work is to implement a UPQC integrated with a photovoltaic (PV) system to mitigate power quality problems in the power system, and boosting the grid supply through power injection from the PV system. Methodology. One of the less complex and effective ways to improve the grid’s voltage quality is by using the unit vector template generation (UVTG) strategy as the composition technique (UPQC-P) through the UPQC series compensator. The synchronous reference frame (SRF) strategy through the UPQC shunt compensator to improve the current quality on the load side is used. To further optimize the SRF strategy, it is used the snake optimization (SO) to find the optimal values for the PI controller’s parameters. Results. The UPQC-PV is used to mitigation the power quality issues in the grid and loads by UVTG and SRF techniques in series and shunt compensators, respectively. Scientific novelty. The composition technique (UPQC-P) through a series compensator and uses the SO for tuning the PI controller in the shunt compensator. Practical value. This study reduces the total harmonic distortion (THD) in the load voltage to 0.57 %, while the THD in the grid voltage remains at 10 %. It restores the load voltage to its reference value of 230 V during voltage sags (down to 161 V) and swells (up to 300 V) in the grid. Additionally, it mitigates the low power factor on the load side (0.707 lagging) to achieve a unity power factor in grid current, balances the unbalanced load current to a balanced grid current, and enhances grid stability by injecting power from the PV system into the grid. References 33, table 3, figures 7.

Comparative analysis of numerical, evolutionary and metaheuristic methods for experimental implementation of selective harmonic elimination in a five-level emerging inverter

M. Naidji, A. E. Toubal Maamar, M. Boudour, A. Garmat, A. Aissa-Bokhtache — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. Multilevel inverters (MLIs) are widely used in renewable energy conversion and high-performance power applications due to their ability to generate output voltages with low harmonic distortion and reduced switching stress. Selective harmonic elimination (SHE) remains one of the most effective modulation strategies for suppressing low-order harmonics; however, its practical implementation relies on solving nonlinear transcendental equations that often require robust and efficient computational methods. Problem. Determining optimal switching angles for SHE in MLIs remains a challenging optimization problem because of the nonlinear, non-convex nature of the governing equations and the need to simultaneously preserve the fundamental voltage component while eliminating selected harmonics. The choice of an appropriate numerical or optimization-based solution method directly affects computational efficiency, robustness, and practical implementability. The goal of the work is the reducing harmonic distortion of output voltage and determining optimal switching angles of a single-phase 5-level inverter using the Newton-Raphson (NR) method, particle swarm optimization (PSO) and genetic algorithm (GA). Methodology. The operating principle and harmonic model of the inverter are first established using Fourier series analysis. The SHE problem is formulated as a system of nonlinear equations subject to ordering constraints. The NR method is used as a fast numerical solver, while PSO and GA are employed as evolutionary and metaheuristic optimization techniques capable of handling non-convex search spaces. All algorithms are implemented in MATLAB/Simulink over a range of modulation indices. Experimental validation is carried out using an Arduino Mega 2560-based prototype, where the optimized switching patterns are executed in real time and the output voltage is analyzed using oscilloscope and harmonic measurement tools. Results. The three approaches converge to identical switching-angle solutions over the investigated modulation range, confirming the consistency of the formulation. Simulation results demonstrate effective elimination of the 3rd harmonic and its multiples, with the total harmonic distortion of the output voltage decreasing from 28.42 % at M = 0.55, f = 1 kHz to 14.88 % at M = 0.55, f = 10 kHz. In terms of computational efficiency, NR-SHE achieves the shortest execution time (0.516 s), while PSO-SHE (10.237 s) and GA-SHE (23.289 s) require longer computation. Experimental waveforms and harmonic spectra closely match the simulation results, validating the proposed approach. Scientific novelty. This work provides a unified comparative analysis of numerical, evolutionary and metaheuristic methods for SHE applied to a 5-level emerging inverter with a reduced switch count (6 switches instead of 8 in a conventional 5-level H-bridge). In addition, it demonstrates the feasibility of executing SHE-based modulation schemes on a low-cost Arduino microcontroller. Practical value. The presented results offer practical guidance for selecting suitable computational methods for SHE in MLIs and confirm that efficient harmonic control can be achieved using inexpensive embedded platforms. The findings are relevant for research, prototyping and educational applications in industrial electronics and power conversion systems. References 21, tables 5, figures 12.

Normal and degraded operation of the open-end winding induction machine fed by 2-level inverters in cascading

A. Nayli, S. Guizani, F. Ben Ammar — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. The machine-converter system is a prevalent and essential configuration, widely used not only in variable-speed industrial drive applications, but also in high-tech transportation and power fields. Problem. Conventional drive systems, particularly those supplied by standard 2-level inverters, face major challenges regarding the enhancement of their dynamic performance and drive availability. To overcome these limitations, a solution involves utilizing the open-end stator winding induction machine associated with cascaded 2-level inverter topologies. The goal of this work is to improve the availability of the drive system by increasing its degrees of freedom through the association of an open-end winding induction machine by two cascaded 2-level inverters. Methodology. The mathematical modeling of this machine is presented and validated using MATLAB/Simulink. To evaluate the machine’s performance, it is first powered by two cascaded 2-level inverters and subsequently by three cascaded 2-level inverters. Following this initial evaluation, the machine is then fed by two cascaded 2-level inverters operating in degraded mode. This analysis features different failure configurations, and the specific operational conditions that must be respected. Results. This topology enhances dynamic performances and enables effective power segmentation as well as a degraded mode operation. These benefits are confirmed by the simulation results. The scientific novelty is based on demonstrating the effectiveness of degraded mode control, which gives the machine-cascaded inverters topology a superior advantage in terms of reliability and performances. Practical value. This topology provides a highly reliable and fault-tolerant drive solution, ensuring better performance during normal operation and better availability after an inverter failure. References 15, tables 1, figures 24.

Bidirectional DC/AC converter for flexible distributed energy integration into AC microgrids

N. T. Vinh, D. T. Anh — Mon, 02 Mar 2026 00:00:00 +0200

Introduction. This work focuses on the development of microgrids in remote areas, islands and regions frequently affected by natural disasters, particularly in Vietnam and other island countries in Asia. Problem. The converters perform direct and isolated energy conversion to AC or DC microgrids, which are distributed grids that integrate various distributed energy sources, including renewable energy such as wind power, solar power and others. To enable the system to operate continuously providing stable power, improving the efficiency and effectiveness of distributed power sources by providing a suitable circuit design to limit losses on the main switches and the number of switches and passive components in the converter is minimal. The goal is to develop the internal structure of a boost DC converter into a multi-port converter connected to the storage system and the AC microgrid under the condition of reducing the main switching losses with the condition of intermittent charging of the storage system during the operating period of the solar power source. Methodology. The study uses the switching adjustment method and modeling simulated to analyze the operating conditions adapted to the application system. Results. Analytical expressions were derived for calculating currents, voltages, losses on components, main switches, and conventional switches. The influence of storage circuit switching on reducing losses in the main switch is shown for the operating cases. Scientific novelty. Using the developed simulation model, new expressions were derived that allow us to establish operational dependencies that reveal the relationships between the parameters of the storage device’s switching components. These dependencies determine the efficiency and performance of the operational function, meeting the requirements of the microgrid system. Practical value. Enhance the efficiency of utilizing distributed energy sources and improve the conversion efficiency of flexible operation converters for AC or DC microgrids in the power system. References 30, tables 2, figures 22.