Electrical Engineering & Electromechanics

Protection of workers against the magnetic field of 330-750 kV overhead power lines when performing work without removing the voltage under load

V. Yu. Rozov, S. Yu. Reutskiy, K. D. Kundius — Fri, 21 Jun 2024 00:00:00 +0300

Problem. One of the acute problems that needs to be solved when performing repair work under voltage on power transmission lines (PTLs) is the protection of workers’ health from high-intensity electromagnetic fields. Goal. The purpose of the work is to develop the methodological foundations for the protection of workers from the magnetic field (MF) of the 330-750 kV PTL during repairing work without removing the voltage and under loading. Methodology. A methodology for calculating the maximum allowable PTL loading factor has been developed. It limits the flux density of the MF in the working area of the power transmission line to the maximum permissible level of sanitary standards for the given period of work at the potential and the minimum thickness of the protective layer between the wires and the worker’s body. Originality. Methodological principles for protecting workers from magnetic fields have been created. They are based on the joint use of the developed method of mode load minimization and the method of increasing the working distance, and the developed method of calculating the maximum allowable loading factor of PTLs. Practical value. The graphic dependence of the maximum allowable loading factor of the PTL is proposed as a function of the required working time and the thickness of the introduced additional protective layer between the wires and the body of the worker. It allows one quickly determines the maximum allowable loading factors to conform the accepted limit-allowable normative level of flux density of MF for various types of PTLs 330-750 kV. References 45, tables 1, figures 10.

Influence of permanent magnet parameters on the performances of claw pole machines used in hybrid vehicles

A. Kimouche, M. R. Mekideche, M. Chebout, H. Allag — Fri, 21 Jun 2024 00:00:00 +0300

Introduction. Claw pole machines (CPM) are commonly used in the automotive industry. Recently, importance has focused on the use and introduction of permanent magnets (PM) in this type of machine to increase the power density. This paper studies the performance of permanent magnet claw pole machines (PM-CPM) used in hybrid electric vehicle applications. The structure considers that the PMs are placed between the claws of the rotor. Purpose. The influence of the PM magnetization effect on the performance of synchronous PM-CPM is analyzed. Radial and tangential magnetizations are applied to obtain the best possible sinusoidal shape of the electromotive force and an acceptable cogging torque. Then, the electromagnetic performance of the PM-CPM is analyzed and evaluated. Furthermore, due to the complexity of the rotor armature, it seems difficult to give a direct relationship between the PM parameters and the machine torque. This led us to study the effects of magnets geometrical dimensions variations on the torque and its ripple. Method. 3D nonlinear model of the machine is analyzed using the finite element method and comparisons between some electromagnetic performances are processed. Results. It was found that the tangential magnetization of PMs makes it possible to obtain a better distribution of the flux density and a minimum of cogging torque mainly responsible for vibrations and acoustic noise. Also, we observed a non-linear variation between the torque and its ripples depending on the dimensions of the PM. In fact, electromagnetic torque increases linearly with PM size but this is not the case for torque ripples. References 22, tables 2, figures 16.

Development of methods for adapting the parameters of spatial end winding sections in 2D circuit-field models of induction-synchronous electric machines

M. I. Kotsur — Fri, 21 Jun 2024 00:00:00 +0300

Introduction. Recently, the theory of a special class of cascade slow-speed non-contact induction-synchronous electrical machines (ISEM) has been developed. This allowed to obtain a combination of positive properties from conventional induction and synchronous electric machines. Problem. The lack of circuit and field models of ISEM imposes restrictions on further research of electromagnetic, mechanical and energy processes, in transient and quasi-steady modes of its operation. Goal. Development of 3D and adapted 2D circuit-field models of ISEM, decomposition methods, and dynamic synthesis with adaptation of electromagnetic parameter coupling conditions at the boundaries of calculated subdomains of ISEM. Methodology. Spatial elements of ISEM design are represented by separate spatial calculation subareas. The conditions of compliance with electromagnetic processes, which are formed by a complete calculation area and separate spatial calculation subareas of ISEM, are accepted. The influence of end effects and the parameters of the frontal parts of ISEM windings are determined by the inequality of the magnetic field energy of separate calculation subareas. These parameters, including end effects, are displayed as circuit elements in the 2D circuit-field model. Results. The obtained combination of 3D area decomposition methods and dynamic synthesis with adaptation of electromagnetic parameters coupling conditions at the boundaries of its calculated ISEM’s subdomains. The proposed technique for determining the resistance and inductive resistances of the frontal parts of the ISEM windings, taking into account edge effects. The accuracy and effectiveness of the proposed methods is confirmed by the results of an experimental study. Originality. An adapted dynamic 2D circuit-field model of transient processes of ISEM has been developed, which allows taking into account parameters of the frontal parts of its windings. Practical value. The proposed methods can be used for various types of electrical machines. References 27, tables 3, figures 12.

Contribution of using a photovoltaic unified power quality conditioner in power quality improvement

C. Bousnoubra, Y. Djeghader, H. Belila — Fri, 21 Jun 2024 00:00:00 +0300

Introduction. With the increasing complexity of power systems and the integration of diverse energy sources, issues such as voltage sags, swells, and signal distortions have emerged as critical challenges. These power quality problems can result in equipment malfunction, production downtime, and financial losses for industries, as well as inconvenience and potential damage to electrical appliances in households. There is an urgent need for enhanced system efficiency. Methods. This objective is effectively achieved through the utilization of the newly proposed power theory, which is rooted in solar photovoltaic (PV) control, in conjunction with the Unified Power Quality Conditioner (UPQC). Purpose. The proposed method incorporates a modified synchronous reference frame scheme, coupled with a phase-locked loop mechanism. This control strategy enables the UPQC to effectively mitigate power quality issues. Novelty. PV-UPQC is utilized to uphold power integrity in the presence of diverse current and voltage distortions. This device, known as a multi-objective power conditioning apparatus, serves the purpose of maintaining power quality. PV-UPQC incorporates both a shunt and series voltage source converter, which are interconnected through a shared DC-link. Additionally, the PV system is interconnected at the DC-link of the UPQC in order to supply power to the load. Results. In this study, a novel approach is presented for controlling the UPQC, aiming to address power quality concerns such as unbalanced grid voltage and harmonic distortions and enabling us to control active and reactive power. References 16, tables 2, figures 15.

Photovoltaic system faults detection using fractional multiresolution signal decomposition

A. Lanani, D. Djamai, A. Beddiaf, A. Saidi, A. Abboudi — Fri, 21 Jun 2024 00:00:00 +0300

Introduction. In this paper, we present an innovative methodology based on fractional wavelets for detecting defects in photovoltaic systems. Photovoltaic solar systems play a key role in the transition to a low-carbon economy, but they are susceptible to various defects such as microcracks, wiring faults, and hotspots. Early detection of these anomalies is crucial to prevent energy losses and extend the lifespan of installations. Novelty of the proposed work resides in its pioneering nature, leveraging a family of fractional wavelets, with a specific emphasis on fractional Haar wavelets. This approach enhances sensitivity in anomaly detection, introducing a fresh and promising perspective to enhance the reliability of photovoltaic installations. Purpose of this study is to develop a defect detection methodology in photovoltaic systems using fractional wavelets. We aim to improve detection sensitivity with a specific focus on low-amplitude defects such as microcracks. Method. Our innovative methodology is structured around two phases. Firstly, we undertake a crucial step of filtering photovoltaic signals using fractional Haar wavelets. This preliminary phase is of paramount importance, aiming to rid signals of unwanted noise and prepare the ground for more precise defect detection. The second phase of our approach focuses on the effective detection of anomalies. We leverage the multiresolution properties of fractional wavelets, particularly emphasizing fractional Haar wavelets. This step achieves increased sensitivity, especially in the detection of low-amplitude defects. Results. By evaluating the performance of our method and comparing it with techniques based on classical wavelets, our results highlight significant superiority in the accurate detection of microcracks, wiring faults, and hotspots. These substantial advances position our approach as a promising solution to enhance the reliability and efficiency of photovoltaic installations. Practical value. These advancements open new perspectives for preventive maintenance of photovoltaic installations, contributing to strengthening the sustainability and energy efficiency of solar systems. This methodology offers a promising solution to optimize the performance of photovoltaic installations and ensure their long-term reliability. References 21, tables 3, figures 10.

The method for design of electromagnetic hybrid active-passive shielding by overhead power lines magnetic field

Fri, 21 Jun 2024 00:00:00 +0300

Aim. Development of the method for designing electromagnetic hybrid active-passive shield, consisting from active and multy-circuit passive parts, which is characterized by increased effectiveness of reducing the industrial frequency magnetic field created by two-circuit overhead power lines in residential buildings. Methodology. The designing problem of electromagnetic hybrid active-passive shield including robust system of active shielding and multy-circuit passive shield of initial magnetic field comes down to a solution of the multy-criteria two-player zero-sum antagonistic game. The game payoff vector calculated based on the finite element calculations system COMSOL Muliphysics. The game solution calculated based on the particles multyswarm optimization algorithms. Results. During the design of the electromagnetic hybrid active-passive shield the coordinates of the spatial arrangement of 11 circuits passive shield and the coordinates of the spatial location of one compensation winding, as well as the current and phase in this winding of the active shielding system are calculated. The results of theoretical and experimental studies of hybrid active and multy-circuit passive shield by magnetic field in residential building from two-circuit power transmission line with a «Barrel» type arrangement of wires presented. Originality. For the first time the method for designing hybrid active and multy-circuit passive shield, consisting from active and multy-circuit passive parts, which is characterized by increased effectiveness of reducing the magnetic field of industrial frequency created by two-circuit overhead power lines in residential buildings is developed. Practical value. Based on results of calculated study the shielding efficiency of the initial magnetic field what is confirmed by experimental studies determined that shielding factors whith only multy-circuit passive shield is more 1.2 units, whith only active shield is more 4 units and with electromagnetic hybrid active-passive shield is more 6.2 units. It is shown the possibility to reduce the level of magnetic field induction in residential building from two-circuit power transmission line with a «Barrel» type arrangement of wires by means of electromagnetic hybrid active shielding with single compensating winding and multy-circuit passive shielding with 11 circuit passive shield to 0.5 μT level safe for the population. References 51, figures 17.

Enhancing grid stability and low voltage ride through capability using type 2 fuzzy controlled dynamic voltage restorer

Ch. Sajan, P. Satish Kumar, P. Virtic — Fri, 21 Jun 2024 00:00:00 +0300

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.

Statistical approach for insulation coordination of high voltage substation exposed to lightning strikes

S. Bedoui, A. Bayadi — Fri, 21 Jun 2024 00:00:00 +0300

Introduction. Insulation coordination requires accurate prediction of overvoltages at various points within a substation. Computer simulations of electromagnetic transients in real structures of substations become more precise due to the improvements of used models. Goal. This paper discusses in a first step the use of the modified ZnO arrester dynamic model alongside other substation equipment models, considering electrical phenomena like the corona model for reproducing the stresses that lightning can cause in an air-insulated substation and (method) then conducting a statistical approach based on the Monte Carlo method. The implemented MATLAB/ATP procedure estimates not only the substation Mean Time between Failures (MTBF), but also is used to select surge arresters or substation basic insulation levels (BILs). In this procedure ATP transients program is used to calculate lightning overvoltages and multicore environment for the calculations. Results. The obtained MTBF curves offer guidance for selecting appropriate insulation levels based on specific system requirements and conditions. The obtained results comply well with existing international insulation standards. This valuable approach significantly contributes to the field of lightning protection. References 31, tables 3, figures 10.

Plasma acceleration in the atmosphere by pulsed inductive thruster

Fri, 21 Jun 2024 00:00:00 +0300

Introduction. One of the directions of development of plasma technologies consists in the formation of gas-metal plasma formations and throwing them to a certain distance. Known thrusters of plasma formation either have an electrode system that is prone to erosion, or a discharge system in a solid dielectric substance in which ablation occurs, or a complex gas-dynamic system with fuel supply. They do not provide acceleration of plasma formation in the atmosphere for a significant distance. Purpose. A theoretical and experimental study of electromechanical and thermophysical processes in a plasma thruster, which ensures the formation of a plasma formation due to thermal ionization by an induced current in a thin conductor layer during a high-voltage discharge on an inductor and the accelerating of a plasma formation in the atmosphere for a significant distance. Methodology. The proposed concept of a plasma thruster, in which the inductor inductively interacts with a combined armature, which includes an aluminum armature in the form of a thin (0.5-1 μm) foil, a copper armature made of a thicker foil (35-50 μm).On the basis of a mathematical model that takes into account the uneven distribution of currents in the inductor and conductive armatures, the features of the process of acceleration the combined armature in the atmosphere were established and experimental studies were carried out. Results. The electromechanical and thermal characteristics of the plasma thruster were calculated. It was established that the choice of the thickness of the dielectric layer of the armature, to which the aluminum and copper armatures are attached, is determined by the energy balance between the heating temperature of the aluminum armature and the electromechanical indicators of the thrower. Scientific novelty. It was experimentally established that the greatest density and homogeneity is observed in the middle of the plasma formation, which has the shape of a torus, moving away from the dielectric sheet on which the aluminum armature was located. As the voltage of the capacitive energy storage increases, the induced current density in the armature increases and the plasma formation becomes more uniform. Practical value. In comparison with the experimental results, the calculated current in the inductor coincides both in shape and in magnitude with an accuracy of 7 %. The biggest difference between the calculated and experimental currents of the inductor occurs when the aluminum armature is thermally destroyed. The transition of an aluminum armature into a plasma formation depends significantly on the voltage of the capacitive energy storage. References 26, figures 16.