IEEJ Transactions on Electrical and Electronic Engineering最新文献

In this study, we propose self-retrieval learning, a self-supervised learning method that does not require an annotated dataset. In self-retrieval learning, keywords extracted from documents are used as queries to construct training data that imitate the relationship between query and corpus, such that the documents themselves are retrieved. In the usual supervised learning for information retrieval, a pair of query and corpus document is required as training data, but self-retrieval learning does not require such data. In addition, it does not use information such as reference lists or other documents connected to the query, but only the text of the documents in the target domain. In our experiments, self-retrieval learning was performed on the EU and UK legal document retrieval task using a retrieval model called DRMM. We found that self-retrieval learning not only does not require supervised datasets, but also outperforms supervised learning with the same model in terms of retrieval accuracy. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

The rapid development of new energy sources, such as offshore wind power and photovoltaic power, has provided a new solution to the problem of power supply for islands far from the mainland. Wave energy is a kind of renewable energy originated from the ocean, but the existing island power supply programs seldom consider this favorable natural condition. In addition, seawater variable-speed pumped storage is a new idea to consume offshore wind power and improve the reliability of coastal and island power systems. In view of the stochastic and intermittent nature of new energy sources, this paper adopts seawater variable-speed pumped storage power plants as energy storage equipment, and put forward an island power supply scheme with wind power, photovoltaic power generation, wave power generation, pumped storage power plants and diesel generator sets as a multifunctional complementary isolated grid. Firstly, wave energy generators, wind farms, photovoltaic farms, pumped storage power stations and diesel generator sets are modeled separately. Then, considering their respective operating conditions, constraints and load requirements, the optimal scheduling of island microgrids with multi-energy complementarity is constructed. Finally, based on the improved particle swarm optimization algorithm, the model is solved. According to the wind power photovoltaic and wave power output curves of several typical scenarios in an island far away from the mainland, the cost and benefit of different schemes are compared to verify the effectiveness of the optimal scheduling in this paper. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Radio stations are seriously affected by transmission line reradiation interference, but most of the existing methods for analyzing and solving reradiation interference on transmission lines focus on approximating the physical problem through mathematical models and algorithms, and it is difficult to study the correlation between transmission lines and reradiation interference in depth. This paper introduces the characteristic mode theory to study the influence factors of reradiation interference on transmission lines, which can decompose the surface induced current of transmission lines into a series of mutually orthogonal mode currents. This paper verifies the correctness of applying the MS (mode significance) value of the characteristic mode theory to analyze the reradiation interference through a simple transmission line example. Taking a line with 5 towers as an example, by analyzing the characteristic mode currents of transmission lines with different forwarding angles and linear arrangements, we not only verified that the characteristic mode currents can well characterize the reradiation interference, but also verified that the characteristic currents of different modes have a direct connection with the structure of the line, which can be applied in the process of designing or reconstructing the towers of the transmission lines, to predict the influence of different structural parameters on electromagnetic scattering, so as to optimize the tower design to reduce the reradiation interference effects and thus optimize the tower design to reduce reradiation interference. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

In the field of high-frequency transformers, winding losses and core losses constrain the improvement of the power density of planar transformers. Reducing losses on the AC resistor and losses on the core is the key to improving the energy transfer efficiency of planar transformers. Aiming at the half-bridge LLC resonant converter, this paper proposes a novel structure of a four-pillar magnetically integrated fractional-turn planar transformer. In terms of the core structure, according to the principle of magnetic integration, integrate four discrete magnetic cores into a single core, effectively reducing the core volume, so reduces core losses. In the winding, the secondary winding for half-turn structure, compared with the traditional planar transformer, the primary winding and the secondary winding turns ratio from n:1 to 0.5n:0.5, the primary winding and secondary winding loss reduced to the original 1 of 2. The secondary side windings are combined with the windings of the same current direction by suitable arrangement. By increasing the current path, effectively reduces the problem of uneven distribution of current density in the winding and reduces the AC losses on the winding. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Urban car ownership in China is fast increasing as the country's urbanization rate and purchasing power improve. Parking difficulties have become one of the key factors affecting and constraining the efficiency of urban economic and social operations. Shared parking is an efficient strategy for addressing urban parking challenges and increasing parking space use. A thorough analysis was conducted on the influencing factors of conflict events in the process of urban shared parking. Based on the conflict information feedback, a dynamic model was proposed in this study for managing and adjusting the access authorization of shared parking spaces. In urban residential settings, this model helps to optimize and reliably control the sharing rate. Furthermore, this study suggested a conflict resolution strategy based on the priority of occupancy rights in response to the main causes of different kinds of shared parking conflicts. This will help to achieve a fair resolution of shared parking conflicts, increase residents' willingness and satisfaction with the shared parking model, and ultimately support the sustainable growth of urban shared parking. The management mechanism and conflict resolution method proposed in this study offer a technological basis for the effective administration and implementation of urban shared parking. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

In view of the problem of large torque ripple and poor output performance of permanent magnet synchronous motor, a new topology of asymmetric magnetic pole permanent magnet synchronous motor is proposed, and the torque ripple of this motor structure and the suppression method are analyzed. First, the equivalent magnetic circuit method and Lorentz force law are used to derive the analytical formula of torque ripple of the motor. Then, based on the analytical formula, the parameters of permanent magnet of the asymmetric magnetic pole permanent magnet synchronous motor are optimized and verified by finite element software simulation; on this basis, the method of rotor eccentricity is used to further weaken the torque ripple of the motor, and the optimal eccentricity distance is analyzed. The research shows that when the parameters of the magnetic pole of the asymmetric magnetic pole permanent magnet synchronous motor is appropriate, the harmonic content of the air gap magnetic density of the optimized motor is greatly reduced, and the motor has good output characteristics, and the torque ripple is reduced to 5.4%. Finally, the prototype is trial-manufactured and tested. The results show that after optimization, the cogging torque of the motor is reduced, the torque output performance is improved, and the overall motor performance is improved. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

With access to many power electronic loads in a power network, the number of suspicious harmonic sources increases significantly, which makes it highly difficult to trace the position of such sources in the entire network. Starting from the engineering application of harmonic tracing and using power quality monitoring data, a harmonic zoning tracing scheme is proposed based on two-layer clustering. Based on the characteristics of harmonic measurement data, k-Shape, a time-series clustering algorithm based on waveform similarity is adopted. By calculating the morphological distance between the harmonic voltage sequences, the similarity of data fluctuation is measured, and the correlation information associated with harmonic pollution is mined. On this basis, adaptive density peak clustering is introduced to improve the k-Shape algorithm. It solves the local minimization problem caused by the random selection of initial clustering centers, and realizes the adaptive selection of the optimal number of clusters. The proposed method can effectively realize the regional positioning of multi-harmonic sources, reduce the suspected range of dominant harmonic sources, and is suitable for traceability analysis in the scenario of a large number of harmonic sources. The IEEE 123 node network and monitoring platform data confirm the practicality and effectiveness of the proposed method. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Various mainstream target tracking algorithms based on Siamese networks are gradually becoming a trend in the field of deep learning tracking due to their concurrent advantages of accuracy and speed. Most Siamese network-based trackers describe the tracking of a target object as a similar matching problem, and these trackers have achieved more advanced performance in several public tests. Most trackers often suffer from tracking drift or performance degradation owing to the non-updating of the template in the first frame and the target appearance encounters disturbing environments such as occlusion and drastic deformation. Therefore, to address this problem, this paper introduces a template updating mechanism and proposes a refine structure network based on the template updating of Siamese networks as well as the greater similarity of target features in two adjacent frames, which improves the tracking accuracy while limiting the amount of computation using an anchor-free method in order not to lose the tracking speed, and only needs to be trained by selecting the most suitable pre-training network, thus greatly reducing the amount of network computation. Meanwhile, in the application of the refine structure, with the aim of making the weight design of the target localisation module more reasonable, we propose a new Refine Head section and analyze and design the update threshold to optimize the overall network. This method is practiced in SiamFC++ algorithm, which firstly designs the template refine module, inputs the image that needs to be improved, and then outputs it to the Refine Head to complete the template update and applies it to the tracking of the subsequent frames, thereby constituting the SiamTRN (Template-Refine Network). According to the experiments, the improved structure of the method can effectively implement the refine module function and enhance the performance of the tracker on public datasets, such as OTB100, VOT2016, UAV123 and GOT-10 k. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Effective load current distribution is a fundamental aspect of ensuring a stable and efficient DC microgrid operation particularly when utilizing dual active bridge converters. In order to construct an improved piecewise setpoint, this research involves a thorough analysis of the statistical distribution of load profiles and the intrinsic properties of a two-segment piecewise droop controller. Furthermore, a thorough comparison analysis of linear and exponential droop-based approaches is carried out in this paper. To assess the proposed two-segment piecewise droop controller, several simulations and hardware-in-loop scenarios are carried out. Additionally, the conventional discrete piecewise droop control method is compared with the proposed method. Notably, with the proposed method, paralleling dual active bridge converters in a DC microgrid clearly demonstrates a significant improvement in current sharing within a specific operating range. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

With the development of high-voltage direct current (HVDC) engineering around the world, there has been increasing attention to the issue of selecting site for direct current (DC) grounding electrodes since the pollution coming from ground potential and electric field. As previous study result, the distance is closer to the grounding electrode, the influence is greater for ground potential and electric field, as well as vice versa. Through proposing the analysis approach of equivalent interfacial charge accumulating, the article goes beyond this previous general-conclusion and extracts the relative position conception from the mono-distance for further studying on weakening their impacts on the environment. In comparison with the previous results, the research finding shows that the movement of relative position is able to achieve the best distribution of ground potential or electric field corresponding to different soil-layered structure, furthermore, the specific mathematic formula about the best relative position has been derived by the accumulated charge model proposed. Finally, the results have been demonstrated by simulation calculation of the CDEGS software for a practical HVDC project in China, moreover, regarding soil resistivity variation related to the different seasons, the optimized relative position about 13 ~ 24 km has been adopted in the real HVDC grounding project as a suggested site. It reveals that the underlying relative position behind the mono-distance could be applied to selecting the site of grounding electrode as reference in the future. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.