Electrical Engineering Research Articles

Preface: 6th International Conference on Information Science and Electronic Technology (ISET 2024)

We are pleased to announce that the 2024 6th International Conference on Information Science and Electronic Technology (ISET 2024) was successfully held in Venice, Italy during September 07-08, 2024. The objective of this conference is to provide a platform for researchers, engineers, academicians as well as industrial professionals from all over the world to present their research results and development activities in information science, computer applications, mechatronics, electrical engineering, and electronic technology. This conference provides opportunities for the delegates to exchange new ideas and application experiences face to face, to establish business or research relations, and to find global partners for future collaboration. There were over 50 participants attended ISET 2024. During the conference, the conference model was divided into three sessions, including oral presentations, keynote speeches, and Q&A discussion. Their insightful speeches had triggered heated discussion in the conference. Every participant praised this conference for disseminating useful and insightful knowledge. We would like to acknowledge all of those who have supported ISET 2024. Each individual and institutional help were very important for the success of this conference. Especially we would like to thank the organizing committee for their valuable advices in the organization and helpful peer review of the papers. The Conference Scientific Committee Venice, Italy

Digital Traffic Lights: UAS Collision Avoidance Strategy for Advanced Air Mobility Services

With the advancing development of Advanced Air Mobility (AAM), there is a collaborative effort to increase safety in the airspace. AAM is an advancing field of aviation that aims to contribute to the safe transportation of goods and people using aerial vehicles. When aerial vehicles are operating in high-density locations such as urban areas, it can become crucial to incorporate collision avoidance systems. Currently, there are available pilot advisory systems such as Traffic Collision and Avoidance Systems (TCAS) providing assistance to manned aircraft, although there are currently no collision avoidance systems for autonomous flights. Standards Organizations such as the Institute of Electrical and Electronics Engineers (IEEE), Radio Technical Commission for Aeronautics (RTCA), and General Aviation Manufacturers Association (GAMA) are working to develop cooperative autonomous flights using UAS-to-UAS Communication in structured and unstructured airspaces. This paper presents a new approach for collision avoidance strategies within structured airspace known as “digital traffic lights”. The digital traffic lights are deployed over an area of land, controlling all UAVs that enter a potential collision zone and providing specific directions to mitigate a collision in the airspace. This strategy is proven through the results demonstrated through simulation in a Cesium Environment. With the deployment of the system, collision avoidance can be achieved for autonomous flights in all airspaces.

Strain and External Electric Field Engineering of S-Terminated MXene on Selective and Sensitive Detection of N-Containing Compound Gases: A Computational Study.

Gas sensors are used for monitoring hazardous gases and vapors. With the emergence of S-terminated MXene synthesis, herein, we explore the sensing ability of Ti3C2S2 toward N-containing gases, including NH3, NO, NO2, trimethylamine (TMA), and nicotine (NT), using first-principles calculations and a statistical thermodynamic model. We find that Ti3C2S2 exhibits high selectivity to TMA, NO, and NT with moderate adsorption energies of -0.610, -0.490, and -0.476 eV, respectively, minimizing environmental noise from ambient gases. The electronic structure of Ti3C2S2 subtly alters upon adsorption of TMA, NO, and NT, facilitating detectable signals in the sensing device. However, the adsorption of NO2 and NH3 is less pronounced due to weak physisorption (<0.3 eV). Employing engineering strategies including biaxial strain and an external electric field greatly enhances the selectivity and sensitivity of NO2 (NH3) detection by boosting adsorption strength up to -0.351 eV with ε = 5% (-0.370 eV with |E⃗| = 0.6 V/ Å). In addition, the moderate adsorption energies of the gases result in a suitable recovery time in the range of milliseconds, leading to high reusability of the sensing device. The estimated adsorption densities suggest potential coverage of these N-containing molecules even at low concentrations and room temperature. Computational analysis of the sensing capability of Ti3C2S2 using the nonequilibrium Green's function method indicates that it is a promising gas-sensing material. In addition, mechanical modifications, electric field adjustments, and gate voltage alterations could be used to obtain effective sensing materials for N-containing gas detection.

Grounding System Design for Wind Power Generation System Considering the Effective Length of Grounding Conductor

Human safety is the most important factor to determine any grounding system, therefore low‐frequency grounding resistance (LFGR) of wind power generation systems should be very low. Lightning protection is another factor for the grounding system design. Grounding conductors (GCs) are used to reduce the LFGR. A long GC however, does not reduce peak voltages for lightning currents with steep‐front waveshapes. Thus, the GC length is an important factor for an effective grounding system. This paper proposes a method for determining the effective length of GC based on traveling wave theory in time domain. Based on this calculation, it describes a grounding system design for wind power generation systems that considers both, the LFGR and the lightning protection. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Anti‐Interference Sliding Mode Control of PMSM Based on Improved Salp Swarm Algorithm

AbstractAiming at the problem that the control performance of permanent magnet synchronous motor is easily affected by load disturbance during operation, a fractional‐order sliding mode control method combining fractal‐order sliding mode controller (FOSMC) and fractional‐order sliding mode load torque observer (FOSMO) is proposed. The parameters of this method are tuned using the improved salp swarm algorithm (ISSA). Initially, the fractional‐order sliding mode controller is designed by applying fractional‐order calculus theory to enhance the system's response speed. Subsequently, a fractional‐order sliding mode load torque observer is developed to improve the system's anti‐interference capability and robustness due to the slow response and low identification accuracy of traditional load torque observers. Lastly, the control parameters are self‐tuned using the improved salp swarm algorithm due to the difficulty of adjusting them manually. Simulation and experimental results demonstrate that the proposed control method exhibits good convergence, no overshoot, minimal buffeting, and strong robustness against uncertain factors like load disturbances. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Monitoring system for electrical load usage characteristics in electrical engineering building

Electrical energy is becoming increasingly essential for educational activities in electrical engineering facilities, as these activities include the use of electrical equipment. The quantity of electrical loads in buildings escalates annually, resulting in increased demand on existing lines and the original design of building construction. Nonetheless, the positioning and allocation of the load within the panel do not align with the augmentation of the load. Consequently, the load becomes uneven across all three stages. Phase T is experiencing an overload, while Phase R has a lesser burden compared to Phases S and T. The maximum current in Phase T is 36.3 A; the imbalance is excessive, leading to a neutral current of 25.2 A. This is perilous since the present value at the neutral point ought to be zero; if the load remains unregulated, it will lead to a contact voltage in electrical apparatus. The utilization of cables is unsuitable due to the substantial connected load, while the cable diameter is merely 2.5 mm², capable of conducting a maximum current of 21 A. Therefore, it is imperative to reassess the electrical installation in the engineering building to avert short circuit disruptions.

Improved Corona Resistance of Epoxy Resin for Gas‐Insulated Equipment in Nitrogen Gas by Direct Fluorination

Direct fluorination has demonstrated efficacy in modulating the surface electrical properties of epoxy insulators and preventing surface charge accumulation. Comparative corona treatments were conducted on both surface fluorinated (modified) epoxy samples and untreated (virgin/original) samples using a modified electrode setup in a nitrogen (N2) atmosphere. The purpose was to evaluate the resistance of the modified epoxy surface layer against corona discharge. The results of ATR‐IR analysis and SEM surface and cross‐sectional imaging indicate that corona treatment did not alter the chemical composition of the fluorinated sample or the thickness of the fluorinated layer. Based on assessments of potential decay and water contact angle measurements, the surface conductivity of the modified sample was decreased by corona treatment. The wettability of fluorinated sample remained unchanged after corona treatment, and no soluble degradation products were produced. Conversely, the surface conductivity of the virgin sample exhibited an increase following corona treatment, accompanied by the formation of soluble degradation products. These results confirm that direct fluorination improves the epoxy insulator's discharge resistance in N2 and provides technical support for enhancing the electrical performance of epoxy insulators in gas insulated equipment. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Prototype Relationship Optimization Network for Few‐Shot Learning

AbstractFew‐shot learning (FSL) aims to infer labels for new samples based on a few labeled samples. FSL based on prototype metrics emphasizes the distance between unlabeled sample features and prototypes generated from a few labeled samples. However, due to the limited number of samples and the uncertainty of samples, the discrepancy between prototypes and the center of the real features may lead to metric error. This paper proposes the Prototype Relationship Optimization Network (PRON) to alleviate the prototype bias issue by utilizing prototype relationship optimization. The PRON involves three fundamental processes: (i) Constructing a multi‐layer prototype through multi‐layer feature embedding to enhance prototype representation capabilities; (ii) Utilizing prototype relationship interaction network of multi‐layer prototype forms multi‐layer prototype relationships to weaken the influence of uncertainty and strengthen the discrimination; (iii) Introduces a prototype refinement mechanism in the cascade structure to optimize prototype relationship representation. The inductive standard experimental results on three popular benchmark datasets show that the performance of the proposed method is very competitive and comparable to the state‐of‐the‐art FSL methods. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Dynamic Determination Method of Line Drop Compensator Parameters for Voltage Regulators Based on Mixture of Experts Using Real‐Time Information

In this paper, a method for determining line drop compensator (LDC) parameters for step voltage regulators and on‐load tap changers is proposed to avoid voltage violations in distribution systems with voltage fluctuations due to photovoltaic (PV) generation and electric vehicle (EV) charging. Distribution system operators need to effectively solve voltage problems caused by the widespread installation of distributed energy resources with the existing voltage regulators to construct an efficient and rational infrastructure. Our focus was on improving the method for determining the LDC parameters for the existing voltage regulators based on LDC control. A mechanism to dynamically change the LDC parameters depending on the situations in the distribution system was developed by using a mixture of experts, one of the machine learning techniques, and real‐time voltage and power flow information from information technology switches. The power flow calculations were performed using a distribution system model constructed based on the topology, loads, and generation characteristics of an actual distribution system in the Hokuriku region. The effectiveness of the proposed method was evaluated in terms of its improved effect on PV and EV hosting capacity, as well as the impact on the frequency of tap operations of voltage regulators. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Research on Electromagnetic Performance and Rotor Eddy Current Loss Suppression of Ultra‐Low Temperature and High‐Speed Permanent Magnet Motor Materials for LNG Pumps

AbstractThere is no unified material selection principle for ultra‐low temperature and high‐speed permanent magnet motors used in liquefied natural gas (LNG) pumps, and high rotor eddy current losses can easily lead to vaporization of the transported LNG. This article first studies the electromagnetic performance of motor structural component materials at room temperature and ultra‐low temperature environments, and proposes the material selection principles for this type of motor. Based on the experimental measurement results of material electromagnetic performance, the loss characteristics of motors under ultra‐low temperature and room temperature environments were compared. Based on the mechanism of rotor eddy current loss and considering the influence of environmental temperature on the material properties of motors, three optimization methods for rotor eddy current loss are proposed. The impact of different suppression measures on rotor eddy current loss is revealed. The suppression of magnetic conduction harmonics can be achieved by opening stator auxiliary slots and optimizing their size and position. High conductivity metal shielding layers are used and their materials and sizes are optimized, And the use of magnetic slot wedges can simultaneously suppress three types of harmonics. Finally, the suppression principles of different optimization methods on rotor eddy current losses were analyzed, and the optimization effects and advantages and disadvantages of different methods were discussed, providing theoretical reference for the optimization design of high‐speed permanent magnet motors operating in ultra‐low temperature environments. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

A Six‐Axis Asymmetric Parallel Manipulator Co‐Driven by Direct‐Drive and Geared Motors for Enhanced Force‐Sensing Capability

This article introduces a novel six‐axis parallel manipulator co‐driven by motors with and without geared reducers. The design leverages the high stiffness provided by the geared motors and the high force‐sensing capability of the direct drives. When the geared motors move synchronously with their direct‐drive counterparts, the manipulator mimics a Delta robot's spatial translation, while the direct drives double as high‐performance force sensors. An asymmetric design of the manipulator is proposed to allocate a larger portion of torque to the geared motors, raising the overall stiffness of the mechanism. Relations between the external force to the driving torque are derived and the torque redistribution effect of the asymmetric design is illustrated numerically. Experimental results on prototypes of both the symmetric design and the asymmetric design show that direct drives consistently exhibit much higher linearity in the force‐to‐torque relationship compared to the geared drives, and also confirm that asymmetric design alleviates the torque burden on the direct drives. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Implementation of Electrical Engineering Curriculum in the Era of Industry 4.0 in Indonesia: Stakeholder Participants Qualitative Interviews

The rapid development of science and technology has led to fundamental changes in terms of qualifications, competencies, and requirements to enter the industrial world. This has led to the adjustment of the effectiveness of collaboration between industry and higher engineering education, thus necessitating further consideration of engineering higher education curricula that are oriented towards the industrial revolution. The aim of this study is to examine how the electrical engineering curriculum can be adjusted and improved to be more relevant to the technological advancements and industrial demands of the Fourth Industrial Revolution era in Indonesia. This qualitative descriptive study utilizes the Focus Group Discussion (FGD) method and semi-structured online interviews. Stakeholder participants including the heads of Electrical Engineering programs in the top twenty universities in Indonesia have been involved in this study. We explore perspectives on the implementation of the electrical engineering curriculum, its rationale, objectives, methods, and challenges in its execution. Herewith, curriculum revisions are deemed necessary while still adhering to the fundamental principles based on accreditation institution guidelines. The findings highlight that incorporating the latest technologies with a focus on practical skills relevant to the development of Industry 4.0 is essential. The latest technology supporting practical skills for electrical engineering students needs to be improved. Active involvement from all parties in the curriculum implementation is the key to producing competent graduates prepared to face global challenges in the era of the Fourth Industrial Revolution.

A Comprehensive and Pedagogical Treatment of the Origin, Selection, and Manifestations of Proximal Coupling in Magnetic Circuits

Appreciation/understanding of the factors that affect proximal coupling in magnetic circuits and the manifestations of the effect of coupling due to magnetic proximity are of paramount importance in electrical engineering. In this paper and in another companion paper we endeavor dealing with each of the aspects critically and putting them in one place. Mainly three aspects—factors that affect the coefficient of coupling, expressing the coefficient of coupling in terms of the design parameters—thus showing the symmetry of the inductance matrix, and the factors that contribute to the deviation of the voltage/current ratios from turns‐ratio is considered, with the introduction of a new factor—a measure of (a)symmetry between the magnetic paths seen by the associated coils. It is also attempted to counter the wide‐spread myth that the proximal coupling imperfection is because of the air‐medium and to highlight the fact that it can also arise because of and be controlled by providing controlled magnetic shunting between the associated coils—a very useful insight. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

High‐Resolution Cortical Dipole Imaging Using EEG Data Measured with a Small Number of Electrodes Based on the International 10–20 System

Cortical dipole imaging is a common technique utilized to visualize the electrical activity in the brain. However, this technique requires ~100 electrodes from a spatial resolution perspective, resulting in a long preparation time and a heavy burden on the subject. According to the international 10–20 system for recording electroencephalogram signals, 19 electrodes are placed on the scalp of the subject. In this study, high‐resolution cortical dipole imaging using the international 10–20 system was investigated for daily applications. The potential at any position on the scalp was interpolated using multiple regression analysis, and optimum parameter estimation was conducted using the proposed method. The simulation and experimental results suggest that the proposed interpolation method is effective for high‐resolution brain activity imaging when using a limited number of electrodes. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

An Efficient Time‐Sensitive Networking Traffic Scheduling Method for Train Communication Network

As a critical system of rail train, the train communication network (TCN) is an integrated central platform that is used to realize the train operation control, condition monitoring, and data transmission. With the development of train intelligence, the scale of data flow in TCN continues to expand, and the control data and monitoring data must be real‐time transmitted to ensure the safe and reliable operation of the train. Time‐sensitive network (TSN) can be applied as the next‐generation TCN solution, which provides end‐to‐end data transmission with extremely low delay and high reliability based on Ethernet. For the application of TSN technology in TCN, a single frame simple scheduling method is proposed to effectively reduce the worst end‐to‐end delay of the entire network, which improve the real‐time performance of TSN‐based TCN. The network topology and data flow characteristics in TCN are analyzed, a series of scheduling constraints are constructed, and the satisfiability modulo theories (SMT) is used to obtain a gate control list (GCL) to ensure the real‐time performance of time‐trigger streams. Finally, the TCN simulation model is established using OMnet++ software, the experiment results show that the proposed method can effectively reduce the overall delay and jitter, and meet the real‐time requirement of TCN. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

An Improved Whale Optimization Algorithm with Adaptive Fitness‐Distance Balance

AbstractWhale optimization algorithm (WOA) is a new bio‐meta‐heuristic algorithm presented to simulate the predatory humpback whales' behavior in the ocean. In previous studies, WOA has been observed to exhibit lower accuracy and slower convergence rates. In this paper, we propose an improved the WOA by innovatively incorporating an adaptive fitness‐distance balance strategy, namely AFWOA. AFWOA can continuously and efficiently identify the maximum potential candidate solutions from the population within the search process, thus improving the accuracy rate and convergence speed of the algorithm. Through various experiments in IEEE CEC2017 and an ill‐conditional problem, AFWOA is proven to be more competitive than the original WOA, several other state‐of‐the‐art WOA variants and other four classic meta‐heuristic algorithms. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Quality inspection method of BIM model for power grid engineering based on knowledge graph

With the continuous updating of national specifications and industry standards, the traditional manual compliance review method is difficult to meet the needs of the development of the construction industry. This study aims to improve the quality review method of BIM models by using knowledge graph technology. The BIM model of power grid engineering is selected as the research object, and a BIM model inspection system based on knowledge graph is developed to verify whether it complies with the relevant specifications and standards of power grid engineering. By taking the BIM model of an electrical engineering project as a case, an inspection report was generated, and the results verified the feasibility and practicality of this method. This technology provides a new direction for the deep integration of architectural design and information technology.

Self‐Assembling Design Method of Stator Slots for AC Rotating Machines

To maximize the performance of rotating machines, it is essential to establish a design method with minimal arbitrariness. This paper proposes a self‐assembling method to design stator slots for alternating current (AC) rotating machines. First, we develop a line‐current approximation model of the stator winding using pulse‐width modulation technique and realize an ideal spatial magnetic flux density distribution. Subsequently, we design the realistic stator with an acceptable current density of the winding by forming unique slot shapes in a self‐assembling manner under two synthetic conditions using the developed line‐current approximation model as the starting model. The designed stator realizes a rotating magnetic field similar to the conventional design results. Additionally, we perform an analysis of motor rotation characteristics by combining the self‐assembled stator with a surface‐mounted permanent magnet rotor to determine the possibility of a higher output compared to that when using a conventional stator. The self‐assembled motor without relying on empirical rules shows a possibility of further improving the torque characteristics, thereby contributing to designing the AC rotating machines. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Motion Trajectory Based Position Control Scheme for Switched Reluctance Machines

Switched reluctance machines (SRMs) are widely used in electric drive areas. However, due to the machine structure, the large stride angle makes it hard to achieve accurate position control for SRMs. In this paper, a position control scheme based on motion trajectory is proposed for SRM position control. In the proposed position control scheme, the SRM control is divided into the accelerating process, the steady operating process and the regenerating process. Development of the proposed position control strategy contains two parts. First, a Fuzzy logic controller is designed for rotor speed control in the accelerating process and steady operating process. Then, an aim speed regulator is proposed for the regenerating process, in which the aim speed is regulated according to the difference between aim position and real‐time rotor position. In the end, both simulation and experimental results are given to show the effectiveness of proposed motion trajectory based position control scheme. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

SOD‐YOLO: Small Object Detection Network for UAV Aerial Images

With the rapid development of the UAV industry, object detection using UAV has become a research hotspot. However, most current object detection models based on deep learning have large parameter counts and are difficult to deploy on embedded devices with limited memory and computational power. To address this problem, a Small Object Detection network for UAV aerial images SOD‐YOLO based on YOLOv8 is proposed, which can meet the application requirements of resource‐constrained devices while ensuring the detection accuracy. First, cross‐domain fusion attention (CDFA) mechanism is proposed to build the C2f‐Attention module in this paper, which is embedded in the backbone network in order to improve the extraction capability of key object features. Meanwhile, the AIFI_LSPE feature fusion module with improved RT‐DETR and the IoU‐aware query selection mechanism are added to the path aggregation network to improve the accuracy of multi‐scale object detection. In addition, in order to balance the sample size ratio and improve the robustness of the network model, we make a new UAV image dataset named VisDrone2019 Extended Edition (VDEE) using images from the VisDrone2019 and UAVDT public datasets. Finally, Shape‐IoU is used as a loss function to reduce the difference between the object GT frame and the detection frame. Experiments show that SOD‐YOLO has a mAP@0.5 of 42.8% in the VDEE dataset, which is increased by 5.1% over YOLOv8. In the VisDrone2019 dataset mAP@0.5 is 39.2%, an improvement of 5.8% over YOLOv8. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.