Search

The XY model of oil‐paper insulation connects the dielectric properties of oil, paper and oil‐paper system. Its equivalent circuit is the basis of the application of dielectric response technology in the state diagnosis of transformer oil‐paper insulation. To better apply the XY model to the study of the dielectric properties of oil‐paper insulation, the dielectric properties of the coaxial oil‐paper insulation system built in the laboratory, XY model and its equivalent circuits are compared. Then an improved circuit of XY model which can reflect the properties of the oil‐paper insulation more truly is proposed. The results show that there is no difference between the XY model and the coaxial model, and both can well characterize the oil‐paper insulation system. The two equivalent circuits of XY model, "Series to Parallel" circuit and "Parallel to Series" circuit, ignore the current tangential component and the electric field distortion in oil‐paper insulation, respectively, resulting in deviations from the XY model. By introducing a new branch C*XY, the improved circuit can reflect the tangential current and electric field distortion in oil‐paper insulation, which can be completely equivalent to XY model. In addition, there is a characteristic frequency point in the oil‐paper insulation system, where the dielectric loss factor tan δ of oil, paper and oil‐paper system are the same. There is no difference between the XY model and its two equivalent circuits at this point. The characteristic frequency is determined by the dielectric properties of oil and paper, and not affected by the insulation structure. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The frequency‐domain dielectric spectroscopy (FDS) of humid insulating paper has been measured at different temperatures. The data show three independent dielectric processes: electrode polarization, hopping conductivity and interfacial polarization. The dielectric properties of humid insulating paper are composed of hopping conductivity and interfacial polarization, and its equivalent dielectric model can be represented by a Havriliak‐Negami (HN) relaxation branch parallel hopping conductivity. At high temperatures and low frequencies, the measured dielectric spectroscopy bends downward, which is caused by the electrode polarization. In this case, the equivalent dielectric model is composed of the body impedance of insulating paper and the electrode polarization in series. According to the equivalent dielectric model, the components of electrode polarization, hopping conductivity, and interface polarization can be separated, thereby eliminating the parasitic effect of electrode polarization on the dielectric properties of insulating paper. Both of hopping conductivity and interface polarization of insulating paper move toward high‐frequency direction with temperature increasing. For humid insulating paper with a moisture content of 5.9%, the activation energies of hopping conductivity and interface polarization are 1.18 and 0.99 eV, respectively. This difference in activation energies results in the inability of the spectrums of insulating paper to overlap with each other at different temperatures. Based on the insulating paper without oil immersion, the results obtained in this article are not affected by oil or oil‐immersion operations. This provides a reference for exploring the dielectric properties and physical mechanisms of oil‐paper composite insulation materials widely used in high‐voltage equipment. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Assessment of the aging of oil‐paper insulation is analyzed in this article, based on an improved fractional Poynting‐Thomson model, which includes dc and hopping conductivity (P‐T model2). Based on samples of oil paper produced in laboratories with different thermal aging times, it has been found that the proposed improved model provides a better fit and a higher index of coincidence concerning the measured values than the traditional P‐T model and the model that only incorporates the effect of dc conductivity (P‐T model1). Nevertheless, comparing the proposed improved P‐T model with the traditional Cole–Cole (C‐C), Davidson–Cole (D‐C), and Havriliak–Negami (H‐N) models, the improved P‐T model2 also demonstrated a superior fit for the measured value and a higher coincidence index than another model. In addition, there was an excellent exponential relationship between the quantities εa, εb and τ of the improved model and the furfural content of the samples. Consequently, these characteristic quantities could be utilized to estimate the furfural content in the oil‐paper insulation and evaluate the insulation's condition. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The partial discharge in the converter transformer will cause the carbonization of the insulating paper. The high concentration of free carbon particles generated from the insulating paper during the operation of the converter transformer will cause partial discharge, which will aggravate the insulation performance deterioration. For the bi‐directional interaction of carbon particles and partial discharge, the mechanism of insulating paper carbonization caused by partial discharge and the effect of carbon particles on the dielectric strength of oil paper are studied. In this paper, we construct a simulation system of amorphous cellulose to study the carbonization mechanism of insulating paper from the microscopic level. Furthermore, we build a DC voltage experimental platform to carry out partial discharge damage tests of oil‐paper insulation models and to measure the changes in the breakdown voltage with different carbon particle concentrations and diameters. The results show that partial discharge speeds up the cleavage rate of cellulose, generates low molecular hydrocarbon gas and water molecules, and the carbon atoms rearrange into PAH‐like molecules with aliphatic side chains. The surface of the insulating paper will carbonize, then form free carbon particles after peeling off. Afterward, the carbon particles in insulating oil accumulate in the high electric field area and attach to the insulating paper, which will cause electric field distortion and reduce the dielectric strength of oil‐paper insulation. With the increase of carbon particle concentration and diameter, the breakdown voltage of oil‐paper insulation decreases gradually. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The transformer is a core device of the power system, and it is generally considered that the aging of insulating paper is important to the transformer. The aging process of insulating paper is the degradation process of cellulose. If it can be detected regularly, the aging of oil–paper insulating systems can be monitored conveniently. 5‐hydroxymethylfurfural is an important chemical substance produced by cellulose decomposition. It has broad prospects because of its many advantages. The oil–paper insulation system was thermally aged at 80, 90, 100, and 110 °C to measure the concentration of 5‐hydroxymethylfurfural on insulating paper and in transformer oil. In this paper, the concentration of 5‐hydroxymethylfurfural is detected by high‐performance liquid chromatography. The linear correlation coefficient of this method can reach 0.99, and the minimum detected concentration can be reduced to 10 µg/l. Experiments show that the concentration of 5‐hydroxymethylfurfural increases with the aging time, and when degree of polymerization (DP) decreased, the concentration of 5‐hydroxymethylfurfural increased. The correlation coefficient is greater than 0.92, which shows that there is an experimental relationship between the concentration of 5‐hydroxymethylfurfural and DP. The parameters of regression curves are different at different temperatures, but in actual operation, the temperature is low and remains stable. Therefore, 5‐hydroxymethylfurfural is expected to be a new indicator of the aging degree of oil–paper insulation system. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Insulation aging of oiled paper is a common malfunction of transformers. It is of great value to recognize the insulation aging status of oiled paper and predict the service life of transformers using appropriate methods. In this study, an aging state recognition method based on partial discharge was proposed. Partial discharge signals were collected, the feature values were obtained through analysis of the principle component factor, and the state was identified by using a support vector machine. A Weibull distribution‐based method was proposed for the prediction of service life, and the residual life of transformers was determined using failure rate function. Through analysis, it was found that the fault analysis method had an accuracy rate of 80.55% in the recognition of the aging state, which was higher than that of Hidden Markov Model (HMM). In the case analysis, the accuracy rate of the method in recognizing the aging state of 100 transformers reached 82.06%. The accuracy of the failure rate function was also verified in the prediction of service life. This study provides some new ideas for the effective recognition of insulation aging of oiled paper in transformers and the prediction of service life. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In the production of facial oil blotting papers, a certain number of papers must be counted before packaging. Currently, the papers are counted by hand, and this is hard work. Also, there are risks of adhesion of dust and wrinkles. In order to solve these problems, we propose a vision‐based approach. After the papers, which are arranged by shifting, are captured, the proposed image processing steps detect the boundaries of the papers. By counting the detected boundaries, the number of papers can be counted. Since the parameters for the proposed image processing are optimized by genetic algorithm, prior setting by a user is not necessary. For the experiments, an image dataset was constructed with six types of facial oil blotting papers. The proposed method achieved higher F‐measure than in other related works. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In this letter, a disposable micropower source was developed by integrating a microbial fuel cell (MFC) in filter paper. The paper‐based MFC could harvest electrical energy generated by Escherichia coli during the metabolic process. The air‐dried biofilm anode was activated by water for on‐demand electricity generation. This study aimed to optimize the anodic and cathodic materials for maximization of the MFC performance. The concentration of activated carbon powder in the anode and potassium ferricyanide in the cathode were optimized. The paper‐based MFC with the optimum anode and cathode generated a maximum power density of 8.4 µW/cm2. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This study investigated mechanical faults in oil‐immersed power transformers with disc‐type windings. Short‐circuit tests were conducted on eight aged removed transformers. Before the short‐circuit tests, accelerated aging tests were conducted on all the transformers to discuss the life limit of transformers. Six out of eight transformers experienced the internal ground faults. Although the radial electromagnetic force and the tolerance of the insulation paper against it have been mainly focused in discussing the life of the power transformers, the ground faults were triggered by the crush of the pressboard by the axial electromagnetic force. The axial compressive stress applied to the pressboards varies from the transformer to the transformer, depending on the design of the windings. The transformer, whose axial compressive stress was relatively lower, passed the short‐circuit test. However, even for the similar deterioration degree of the pressboard, the transformer, whose axial compressive stress was relatively higher, experienced the ground fault. These results indicate that the axial compressive stress during an external short circuit and deterioration of the pressboard are critical factors that determine the life of transformers with disc‐type windings. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

As energy shortages and environmental pollution continue to worsen, household photovoltaics has gradually become an important part of household energy management. However, with the penetration rate of household photovoltaics increasing, the access of the high‐proportion household photovoltaics (HPHP) will seriously endanger the operation of the distribution network. Therefore, it is urgent to stabilize the voltage fluctuations after the HPHP connected to the grid. This paper proposes a high‐proportion household photovoltaic optimal configuration method based on integrated–distributed energy storage system. After analyzing the adverse effects of HPHP connected to the grid, this paper uses modified K‐means clustering algorithm to classify energy storage in an integrated and distributed manner. Then based on the modified particle swarm optimization (MPSO), the integrated and distributed energy storage system is configured to realize the voltage stability of HPHP. The analysis of the example shows that the method proposed in this paper can effectively improve the power quality. At the same time, it can achieve the goal of economic optimization, which can effectively solve the adverse impact of HPHP grid connection. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Several multimedia applications have recently been implemented on mobile devices, including digital image compression, video compression, and audio processing. Furthermore, Artificial Intelligence (AI) processing has grown in popularity, necessitating the execution of large amounts of data in mobile devices. Therefore, the processing core in a mobile device requires high performance, programmability, and versatility. Multimedia apps for mobile devices typically comprise repeated arithmetic and table‐lookup coding operations. A Content Addressable Memory‐based massive‐parallel SIMD matriX core (CAMX) is presented to increase the processing speed of both operations on a processing core. The CAMX serves as a CPU core accelerator for mobile devices. The CAMX supports high‐parallel processing and is equipped with two CAM modules for high‐speed repeated arithmetic and table‐lookup coding operations. The CAMX has great performance, programmability, and versatility on mobile devices because it can handle logical, arithmetic, search, and shift operations in parallel. This paper shows that the CAMX can process parallel repeated arithmetic and table‐lookup coding operations; single‐precision floating‐point arithmetic can calculate 1024 entries in 5613 clock cycles in parallel without embedding a dedicated floating‐point arithmetic unit. This clock cycle using two's complement‐reduced floating‐point addition implementation decreases 59% than the implementation of straight‐forward floating‐point addition. The implementation of straight‐forward floating‐point additions is improved as two's complement instruction reduced algorithms. Thus, this paper proposes an instruction reduction architecture by modulating the CAMX to directly access the data in the left and right CAM modules from the preserve register. The CAMX has achieved high performance, programmability, and versatility by not embedding a dedicated processing unit. Moreover, assuming the CAMX processes at an operating frequency of 0.1, 0.5, 1.0, or 1.5 GHz, it can process floating‐point additions above approximately 4500 parallelized data, with better performance than an ARM core using NEON and Vector Floating‐Point (VFP). In addition, related works executed by software instruction, dedicated floating‐point arithmetic unit, or both and the CAMX are compared while assuming the same operation frequency. From this result, the CAMX which has 128‐bit and 1024‐entry CAM modules achieves higher performance than the related works executed by only software instructions and by combining software instructions and a dedicated floating‐point arithmetic unit. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The anode electrode plays a vital role in the performance of microbial fuel cells (MFCs) because it has the function of collecting electrons generated by microorganisms living in the anode chamber. In this letter, activated carbon papers fabricated based on ZnCl2‐activated carbon (ZAC) or steam‐activated carbon (SAC) were used as the anodic materials. Escherichia coli was used as an electrogenic bacterium in a two‐chamber MFC. This study compared the performance of ZAC and SAC in the anode. X concentrations (X = 10, 20, and 40 wt%) of ZAC or SAC in the anodes were investigated. The ZAC‐based anode outperformed the SAC‐based anode in terms of MFC‐generated power density. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The evaluation of the failure probability is essential in the reliability‐centered and risk‐based maintenance of power transformers. The breakage of the pressboard in disc‐type transformers is one of the critical factors determining the lifetimes of power transformers. In this paper, a hierarchical method for evaluating the probability of pressboard failure, which is the breakage of the pressboard, in power transformers that considers the axial displacement of the winding is introduced. In the method, the diagnosis of the axial displacement is classified into three distinct classes. In class 1, no diagnosis is implemented, and the probability of failure is evaluated with the maximum possible axial displacement. In class 2, the diagnosis determines whether the winding is axially displaced. When the winding is diagnosed to be displaced, the probability of failure is evaluated with the maximum possible axial displacement. In class 3, the axial displacement is diagnosed quantitatively, and the probability of failure is then evaluated using the diagnosis result. Examples of the evaluated probabilities of pressboard failure are introduced, and the extension of the evaluated lifetimes of power transformers via the diagnosis of winding axial displacement is demonstrated. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In recent years, the object‐tracking algorithm based on Siamese network has gradually become the mainstream algorithm in the field of object tracking due to its characteristics of balancing speed and accuracy. The majority of Siamese‐based trackers only use the first frame extraction template for subsequent tracking in order to prevent the introduction of noise. However, merely with a single initial template employed, it is difficult to achieve the best performance of the tracker in the face of complex tracking environments such as occlusion, motion blur, and non‐rigid deformation. Therefore, the present paper proposes a new multi‐template fusion module based on graph attention network (G‐M module), which consists of two parts: a graph‐attention‐network‐based feature‐embedding module (G module) and a multi‐template fusion module (M module). It can greatly reduce the background noise introduced by template updating while improving the tracker's ability to adapt to changes in object appearance. In addition, in order to maximize the value of G‐M module, the present paper also puts forward a two‐stage template update threshold judgment mechanism. The Pearson correlation coefficient (PCCs) is introduced and combined with APCE and the maximum response value (F‐max) to filter out reliable templates for updating. In this paper, the proposed method is applied to the SiamFC and SiamFC++ trackers. Extensive experiments on mainstream data sets, such as OTB2015, VOT2016, and GOT‐10 k, show that the proposed method can effectively update the tracking template and improve the tracker performance. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Electromagnet coil is mainly composed of enameled wire which wound on the coil skeleton, and the function is to convert the electrical signal into a magnetic signal, which is a very important electric‐magnetic conversion element. When designing the electromagnet coil, usually only the total winding turns and winding inner diameter can be calculated, and the specific design parameters such as the diameter of copper wire, paint layer thickness, and winding turns of each layer can only be selected through experience, indicating that the design method should be improved. In addition, the unreasonable design parameters will seriously affect the power consumption and cost of coil, so it is highly necessary to improve the optimization design method. In order to solve the above problems, an optimization design method for DC electromagnet coil is proposed in this paper. This method simultaneously takes into account both power consumption and manufacturing cost, and can achieve the optimal matching of design parameters. In this paper, the structure of electromagnet coil is introduced, and the theoretical calculation model of resistance is improved first. Then, according to the expected requirements of electromagnet coil for steady current, the optimization design method is proposed and the optimal design parameters are obtained. Finally, the effectiveness of the proposed optimization design method is verified by the test platform of electromagnet coil. The results show that the electromagnet coil designed by the optimization design method fully meets the expected requirements. The relevant research results can provide reference for the optimization design of electromagnet coil, which has a certain engineering practical value. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Oil‐immersed transformers as one of the most important equipment in the power system, the fault prediction of it in advance can effectively reduce the subsequent harm. Aiming at the selection of input features and data sample imbalance in the transformer fault diagnosis model, this paper adopts the recursive feature elimination (RFE) method combined with SMOTETomek comprehensive sampling method to optimize the above problems. First, RFE is used to traverse all the features and filter the optimal combination of them as input features, then SMOTETomek is used to perform balancing operation on the samples of the train set, and finally, whale optimization algorithm (WOA) is used to find the best hyperparameters for support vector machine (SVM), and the results are compared with the diagnostic models operated without processing and after single processing operation, respectively. After several sets of experiments, it is proved that the optimized comprehensive fault diagnosis model performs better on the test set than both the untreated and the singly processed models, which proves the effectiveness of the methodology used in this paper. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes an effective control synthesis strategy to stabilize grid forming converters in the presence of disturbances. The conventional control system for a grid forming converter is based on paralleled and cascaded proportional‐integral (PI) controllers, which are widely used in the industry due to their simplicity and reliability. However, the sequential adjustment of PI gains in different control loops, without consideration of dynamic interconnections limits their performance and capability. To address this limitation, the present paper introduces a control design method based on static output feedback theory. The proposed control scheme reduces the dynamic control design problem to an effective gain scheduling problem. In the proposed methodology, without removing the existing practical control structure, its dynamic parts are moved to the open‐loop system, and simultaneous scheduling of all remaining control gains is achieved during one control design process. MATLAB simulations were conducted to evaluate the performance of the designed control system, and compare it with the conventional control one in terms of step response characteristics. The results demonstrate the superiority of the proposed controller, ensuring system stability and exhibiting improved performance. The proposed control framework provides several advantages, including keeping stability in various disturbance conditions, simultaneous tuning of all control parameters, and no need to change the existing simple control structure. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) technology can completely isolate the equipment from the power supply, and has been widely used. However, the transmission efficiency of WPT system is optimal only as the transmitting coil was completely aligned with the receiving coil. But in practical applications, the mobile devices are all dynamic system, and perfectly alignment of the coils is a very demanding condition. In order to solve this problem, the paper proposed a coil position adaptive adjustment control scheme of WPT system with lateral misalignment or angular misalignment. Firstly, the relationship between transmission efficiency and lateral misalignment and angular misalignment was analyzed. And the research results show that if there is a lateral misalignment between the coils, the transmission efficiency can be optimized by adjusting the angular misalignment. Secondly, based on the hill climbing algorithm, a coil position adaptive adjustment control method was proposed. Finally, a coil position adaptive adjustment WPT system experimental platform was built, and the experimental researches are carried on. The results of the experiment show that as the transfer distance is 0.10 m and the lateral misalignment is 0.12 m, the transfer efficiency can be increased from 38.38% to 55.61% through the proposed control scheme. And the results verify the feasibility and effectiveness of control scheme proposed in the paper. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The accumulation of snow is one of the essential reasons for the significant decrease in the power generation efficiency of PV stations in winter. For this reason, this paper firstly provides a detailed review of the current research into the physical processes and shedding reasons for the natural melting of snow on PV module surfaces. Then, several common techniques to promote snow and ice melting on PV surfaces are discussed, and the feasibility and shortcoming of ultrasonic technology in removing high‐density snow and ice are analyzed in detail. Finally, this paper proposes two snow sensing technologies for PV modules, namely, image processing method and interdigital capacitance method. Among them, the image method based on fixed camera and UAV detection is more suitable for wide area PV power stations, while the interdigital capacitance method is helpful in obtaining snow characteristic parameters, such as icing type and LWC. The relevant research has certain reference significance for PV power stations to formulate a more reasonable snow removal plan and power generation forecast. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a three‐layer coordinated optimization strategy based on fuzzy control of renewable energy sources (RESs), vehicle‐to‐grid (V2G) and energy storage. Firstly, the overall structure of this strategy is introduced, which is composed of V2G management system, renewable energy dispatching system and energy storage (ES) real‐time balancing system. Secondly, the control strategy is proposed for different systems, among them, the V2G management system considers shortage of power grid, forecasted maximum output of RESs, and state of charge (SOC) of electric vehicles (EVs) to calculate the charging plan for each EV in next time interval by fuzzy control algorithm; The renewable energy management system gets the expected shortage state of the power grid in the next period according to the charging plan and the current state of the power grid, then combined with the battery state of the energy storage system, the renewable energy guiding power generation in the next period can be calculated by the fuzzy control algorithm; The energy storage real‐time balancing system can charge or discharge according to the real‐time frequency and shortage of power grid to ensure balance between supply and demand of power grid. Finally, the simulation proves that the three‐layer management strategy proposed in this paper can help grid to cut peak and fill valley effectively, improve the load characteristics of the regional power grid and reduce the amounts of the rejected renewable energy. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In the actual power grid environment, there are severe class imbalances in the data sets of various monitoring systems. The existing deep learning methods are highly dependent on the training data sets, and it is difficult to mine the minority sample features in the imbalanced data sets, resulting in Classification recognition accuracy is severely limited. This paper takes the voltage sag as the research object, and proposes a dataset enhancement method based on an improved balanced generative adversarial network. This method combines the advantages of autoencoder and generative adversarial network, learns the public knowledge in the data set through the initialization training of autoencoder, and uses the majority class sample features to assist in generating minority class samples. In addition, an embedding layer is introduced into the self‐encoder architecture to add label information to the eigenvectors, which solves the problem of strong coupling between the distribution of voltage sag eigenvectors and improves the generation effect of samples. At the same time, the Wasserstein distance optimized by the gradient penalty term is used to guide the model adversarial training, which overcomes the problems of vanishing gradient and mode collapse of the original model. Through experimental analysis, the model can fully extract the features of minority samples under unbalanced data sets, ensure the distribution consistency between generated samples and original samples, and take into account the authenticity and diversity of generated samples, which can effectively improve the recognition effect of deep learning model on minority classes and improve the overall recognition accuracy. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The transformer is the most essential component in electrical power transmission. Once a transformer is installed, it is generally used for decades. When failure occurs in a transformer, serious problems can arise, and numerous electrical components that depend on the transformer may be affected. Thus, deterioration diagnosis of transformers is important. The furfural content in the insulating oil of a transformer is widely used as an indicator of transformer deterioration, as furfural is generated by decomposition of the insulating paper. Although the degree of transformer deterioration can be estimated by measuring the furfural content, this measurement is time‐consuming. This paper proposes a novel method for estimating the amount of furfural contained in insulating oil within a short time. The method is realized by combining spectroscopic analysis in the visible region with a pattern recognition technique. The effectiveness of the proposed method is verified through a series of experiments. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Multi‐port hybrid DC circuit breakers (MP‐HCBs) are rapidly developing due to their obvious advantages in economy compared to traditional two‐port hybrid circuit breakers (HCBs). However, most of the existing MP‐HCB topologies do not have the current‐limiting capability, and a large number of insulated‐gate bipolar transistors (IGBTs) are still needed in their main breakers. In response to the problems, a multi‐port current‐limiting hybrid DC circuit breaker (MP‐CLHCB) based on thyristors is proposed in this paper. MP‐CLHCB uses low‐cost thyristors instead of IGBTs, and suppresses the rise of fault current through current‐limiting branch. In an attempt to prevent the MP‐CLHCB from reclosing in a permanent fault and causing damage to the DC grid again, an adaptive reclosing scheme is also proposed. In this paper, the topology, operation stages, theoretical derivation, and parameter design of the MP‐CLHCB are provided. Finally, the performance of the MP‐CLHCB is verified and compared through simulations in PSCAD/EMTDC. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to deeply study the actual contact state of sealed relay contact surface, restore the contact spots of contact pair, and make up for the deficiency of establishing contact model of contact pair only by theoretical simulation. In this paper, the electrical contact high‐speed camera system is selected to record the kinematic parameters during the pull‐in process of the contact, and the deflection angle and deformation amount when the contact is complete are calculated. The surface height of the contact surface is collected through the non‐contact morphology scanner, and the actual contact morphology is corrected and restored. Finally, the actual contact spots are analyzed by reconstructing the contact difference‐plane. The method studied in this paper can provide a reference for the further study of contact analysis. Establishing the actual contact state of the contact pair of the micro level has a certain guiding role in the establishment of the contact resistance model. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In the actual operation, converter transformer valve side bushings are subjected to high voltages and large current loads with large number of harmonics simultaneously. In our previous papers, using the 3‐D electromagnetic‐fluid‐thermal coupling analysis method, the 3‐D temperature distribution of a converter transformer valve side bushing was researched, and the heating and dissipation characteristics of the bushing were analyzed. However, the electric field distribution of the bushing is affected by the temperature gradient inside the bushing. Related researches about the electro‐thermal coupling field of the bushing are rare and most researches are concentrated on the single factor of voltage or temperature. In this paper, by using the electro‐thermal coupling field simulation method proposed in our previous paper, the effect of the core outline size on the electric field distribution of the bushing under a certain temperature gradient was investigated. In addition, by using the transient electric field simulation method, the electric field distribution of the bushing in one cycle subjected to an actual voltage waveform and the current in temperature rise test simultaneously was analyzed considering the effect of the Joule heating power of the core. The proposed method will be able to provide a computation basis for the structure design and optimization of converter transformer valve side bushings. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Mechanical characterization of cells is important for understanding their behavior. This paper reports on an in situ evaluation of the stiffness of cellular spheroids using a pinching device. The pinching device is integrated with a bimorph piezoactuator and strain gauge. It can pinch an object by combining a piezo bimorph actuator and a thin Si structure and can detect the reaction force from an elastic object using a strain gauge integrated into the thin Si structure. The strain gauge can detect the bending deformation of the device and estimate the reaction force by considering actuation. This paper presents the design of the pinching device and experimental results when used for the in situ evaluation of the stiffness of cellular spheroids. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In the semi‐airborne frequency domain electromagnetic detection, strong noise will be generated due to the attitude change of the receiving coil sensor. However, the existing attitude measurement system cannot be directly used in the semi‐airborne frequency domain electromagnetic system because of the requirement on the volume and accuracy of the instrument. In order to reduce the effect of attitude noise, this paper analyzes the cause and influence of attitude noise in the semi‐airborne frequency domain electromagnetic system, and presents the attitude noise correction method based on coefficient rotation matrix and Kalman algorithm. A high‐performance attitude sensor based on (Micro‐Electro‐Mechanical System (MEMS) technology is used to design an attitude measurement system for the semi‐airborne frequency domain electromagnetic system. The calculated result shows that the required accuracy of the roll angle and pitch angle of the attitude measurement system is less than 0.1°, whereas the required accuracy of the yaw angle is lower. In the field application, the apparent resistivity results show that the imaging profile corrected by attitude error is more consistent with local geological data than that without correction. Consequently, the attitude measurement system and correction method proposed in this paper can improve the detection accuracy of the semi‐airborne frequency domain electromagnetic system significantly. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The XY model is a simplified insulation model for transformers that aims to connect the frequency spectrum of major insulation, insulation paper, and oil. It enables the calculation of the paper's frequency spectrum, facilitating a quantitative evaluation of the transformer's insulation status. Given the scarcity of research addressing the accuracy of the XY model and its corresponding equivalent circuit, this paper investigates the accuracy of the XY model and conducts an in‐depth analysis of the error associated with its equivalent circuit. Firstly, the frequency spectrum of oil‐paper insulations based on the XY model with varying moisture content and structure configurations were measured, followed by the simulation of both the corresponding 2D‐coaxial and XY models. By comparing the results obtained from these simulations with experimental data on oil‐paper insulation, the accuracy of XY model is verified. Subsequently, two variants of the equivalent circuit of the XY model are derived by combining the oil, spacer, and paper differently, which denoted as Type I and II circuits. Finally, we analyzed and explained the errors present in these equivalent circuits compared with the XY model. Our findings show that the width‐thickness ratio of oil‐paper insulation is the most critical influencing factor, while moisture content and insulation structure have a less decisive impact. Notably, for general transformers, as the width‐thickness ratio is between 30 and 70, the relative error of the Type I circuit remains consistently below 0.3% across different frequencies. Consequently, the Type I circuit proves to be a more suitable representation of the equivalent circuit for the XY model in the context of general transformers. © 2024 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Visual SLAM algorithms can obtain a large amount of texture information from the environment and usually perform very well in static scenes, but there are a large number of irregular dynamic points when running in dynamic scenes, which can lead to increased error in SLAM feature point matching and loss of tracking localization. To address this challenge this paper proposes a SLAM system (YVG‐SLAM) that adapts to dynamic scenes. YVG‐SLAM is an improvement on the ORB‐SLAM3 algorithm, integrating the view geometry algorithm and the current powerful YOLOv5 algorithm, while proposing a dynamic feature removal strategy without a priori assumptions to reduce the influence of dynamic targets. In this paper, we first lighten the YOLOv5 algorithm, then process the image frame to get the bounding box, then use the view geometry algorithm to determine the dynamic feature points on the image frame, and finally remove the moving objects in the image frame according to the dynamic feature recognition strategy proposed in this paper. The performance of the algorithm is tested on the TUM RGB‐D and BONN RGB‐D datasets. The experimental results show that the robustness of the proposed algorithm on most video sequences is better than the existing SLAM algorithms dealing with dynamic scenes such as Detect‐SLAM and DynaSLAM, and the RMSE index of the absolute trajectory error measured on high‐speed dynamic video sequences can be significantly reduced by more than 93% compared to ORB‐SLAM3. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper addresses optimization problems subject to an objective function's evaluation‐number constraint arbitrarily given in advance. These problems are practical for black‐box objective functions which cost much money and/or time per evaluation because money and/or time constraints are typically applicable in real‐world projects. This paper suggests a new solution strategy that can be used to adapt metaheuristics to evaluation‐number constraints arbitrarily given in advance. The proposed strategy updates the setting parameters of a target metaheuristic algorithm for every generation by solving a fixed small‐size optimization problem related to the evaluation‐number constraint. It has the advantage of being insensitive to the effects of dimensionality increases in principle. The effectiveness of the proposed strategy is confirmed by numerical experiments with two well‐known metaheuristics, i.e., the particle swarm optimization algorithm and the differential evolution algorithm. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In electromagnetic launcher, the pulsed current is concentrated by contact state, current skin effect (CSE) and velocity skin effect (VSE), and heat the material locally. It will lead to melt or degradation, reducing stability and service life of the launcher. In order to study the current distribution with all these various influences, a 3D transient current analysis model with dynamic conductivity assignment and contact layer is proposed in this paper. It is found that the short contact length in armature moving direction can make two peaks overlap caused by CSE and VSE, and VSE can disturb the current distribution in horizontal direction. When designing armatures, it is recommended that the contact length in the moving direction should be long enough during the entire launch process, so to isolate the two peaks, and that the central length of the armature tail should be longer than the lateral length, so to prevent the current from concentrating more at the lateral edge. These conclusions help the optimization of the launcher structure to reduce local damage caused by current concentration and extend service life. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Energy internet zones (EIZ) supply multiple energy carriers to customers in certain regions. They can achieve high energy efficiency by energy cascade utilization. In mid‐term, they participate in the wholesale market and retail market simultaneously. Customers can shift their energy use among different hours and energy carriers to satisfy demand according to the retail prices. Unfortunately, multiple energy systems and markets bring various uncertainties on demand and prices. In this paper, the weekly bidding strategy for the EIZ is proposed to determine the optimal bilateral contracts to sign and the optimal energy retail prices. In retail market, the satisfaction degree and elasticity matrix describe customers' response. Distributionally robust optimization is adopted to consider the distributional uncertainties of random variables and Worst‐case Conditional Value‐at‐Risk is employed for risk management. The distributional uncertainties of pool prices and elasticity matrix are discussed in this paper. An EIZ in Shanghai, China is adopted to illustrate the proposed strategy. The results have great resistance to distributional uncertainties. The risk aversion and satisfaction degree affect the EIZ's strategy in wholesale market and retail market, respectively. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

For ultra‐high‐voltage (UHV) systems together with high‐voltage facilities, more rationalized insulation coordination and equipment design are required. To this end, making large‐scale and long‐term field lightning‐strike observations, large amount of and practical experiments, and introducing new analysis techniques have enabled the development of advanced technologies capable of transforming conventional techniques. This paper reviews what has been developed in a Japanese electric power company in this regard. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

With the continuous development of intelligent refrigerators, users are having higher and higher requirements for smart management of refrigerator contents. When using traditional machine learning algorithms to deal with refrigerator ingredients classification, problems such as slow recognition speed and low accuracy would often arise. At the same time, the classification accuracy is easily affected by the location of the content. Therefore, this paper uses continuous asymmetric convolutions and depthwise separable convolutions to improve the original Inception model and builds a classification prediction network based on the improved Inception model. The steps to applying the said model is as follows: First, we put the Radio Frequency Identification (RFID) tag on the food in the refrigerator, and then we collect the antenna data RSSI received by each tag through the reader. Finally, the RSSI is preprocessed and entered into the classification network to determine the location of the label. The proposed classification network has the advantages of possessing a simple structure, easy expansion of network depth, and fewer training parameters. The experimental results show that compared with other machine learning algorithms and pure convolution networks, the lightweight network model based on the improved Inception structure demonstrates great superiority. Compared with the original Inception structure, the enhanced network model is more lightweight. The number of parameters is reduced by 50%, and the amount of float‐point operations is reduced by 34%. Meanwhile, the accuracy of the lightweight model has been improved by 0.6%. Thus the improved model has better prediction performance in the classification of refrigerator content. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The grid‐forming converter (GFC) is used to regulate the voltage and frequency of a local grid. However, due to the limited current capacity, the GFC must actively modify its control strategy when a serious external fault occurs, thus to avoid the possible damage caused by overcurrent. This paper proposes a novel voltage reference generation method for GFC based on the external equivalent impedance magnitude (EEIM), which has the following merits: (i) the faulty phase currents and the non‐faulty phase voltage can be controlled within their operational limits. (ii) The voltage reference unbalance factor (VRUF) of the GFC can be adjusted flexibly if necessary. Then, in order to achieve the optimal support effect for the faulty phase voltages, a two‐stage GFC fault control strategy is proposed in this paper. In the first stage, the fault type is judged by computing and comparing the EEIM of each phase. In the second stage, the voltage reference mode is determined according to the fault type, and the VRUF is adjusted to its optimum value through a search algorithm. Simulation results based on Matlab/Simulink verify the effectiveness of the proposed GFC fault control strategy in terms of current limiting and faulty phase voltage support. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

It is of great importance to build an accurate model for the multi‐step forecasting of household power consumption. In recent years, more and more researchers have focused on adopting hybrid models to execute forecasting due to the irregularity and nonlinearity of power data. However, existing forecasting models usually make predictions directly on original data. This paper introduces secondary decomposition algorithm used to decompose primal data. We use singular spectrum analysis (SSA) to decompose the original series into several subseries, utilize variational mode decomposition (VMD) optimized by whale optimization algorithm to decompose the subseries with the highest frequency into several intrinsic mode functions. Then all subseries obtained from SSA and VMD are fed into long short‐term memory model to get predictions. In order to confirm the validity of proposed model, this paper performs several experimental analyses. The results of experiments show that the proposed model effectively improves the accuracy of forecasting. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Power line insulator defect identification usually suffers from complex backgrounds, small defect target sizes, and inconspicuous defect features. Traditional identification methods based on image processing, image analysis, and pattern classification have many limitations in solving the aforementioned problems. In recent decades, deep learning classification methods have gradually replaced traditional identification methods in the task of power line insulator defect identification. To accurately identify the locations of insulator defects, this paper proposes an insulator defect detection algorithm using an improved lightweight YOLOv4‐tiny network (ILYTN). First, the CBL (Conv‐BN‐LeakyReLU) modules of the backbone network are replaced with MobileViT blocks to enhance the feature extraction capability of the backbone network. Second, coordinate attention (CA) is introduced in the feature fusion part to improve the network's ability to focus on the location of defects. Finally, an EIOU (efficient intersection over union) loss function, instead of the original CIOU loss function, is used so that the convergence speed of the network can be improved. To verify the effectiveness of the proposed algorithm in this paper, the mViT‐yolo algorithm is compared with the mainstream Faster‐RCNN algorithm, SSD algorithm, YOLOv3 algorithm, and YOLOv4‐tiny algorithm. The experimental results show that the algorithm proposed in this paper outperforms all the above algorithms in terms of detection accuracy. Compared with the traditional YOLOv4‐tiny algorithm, the proposed algorithm increases the mean average precision (mAP) by 1.64%, the average precision (AP) of missing insulator defects by 0.32%, and the average precision (AP) of broken insulator defects by 4.96%. © 2023 The Authors. IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Nowadays, fish farming plays an essential role in aquaculture. In the process of fry sales, the traditional manual counting method takes a great deal of time. Because the fish are constantly moving in the water, they are difficult to count and are likely to be unnecessarily damaged. With the rise of computer vision, fry counting based on image processing is also developing. It has the advantages of having high accuracy and fast processing speed. The primary counting process is divided into detection, adhesion segmentation, and fry counting. First, we improved the maximum interclass variance threshold selection method, and we extracted the histogram features under different channels to detect the fry; then, a matching segmentation method based on concave and skeleton crossing points was used to segment the adherent fry to improve the counting accuracy, the concaves were detected by CNN. We tested the method on real fry data sets, and the average accuracy reached 97%. Our approach had better accuracy than any existing current fish counting methods. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

During the operation of the independent DC microgrid, the bus voltage will fluctuate with the random changes of the load and source. To maintain the stability of the bus voltage, a control strategy needs to be introduced in the DC microgrid. According to the bus voltage change of DC microgrid, this paper establishes a large‐signal mathematical model of DC microgrid with constant power load. Taking the bidirectional DC‐DC converter as the control object, a sliding mode variable structure controller based on the washout filter is introduced, and the bus voltage is stabilized at the desired voltage value through the selection of control parameters. The simulation experiment results show that the control strategy proposed in this paper can effectively restrain the fluctuation of the bus voltage under the condition of random changes of the load and source and has strong robustness. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Aiming at the problem of unnecessary waste of power resources in the power system caused by the uncertainty of wind farm output, and then affecting the economics of the system. This paper proposes a power system scheduling model based on wind power output forecasting errors. In the forecasting stage, in view of the defect that the Fruit Fly Optimization Algorithm (FOA) is easy to fall into the local optimal value, an Adaptive Mutation Fruit Fly Optimization Algorithm (AMFOA) based on the flavor concentration variance is proposed. And then, the parameters of Extreme Learning Machine (ELM) are optimized by AMFOA to predict the wind power output. In the scheduling phase, a limit scenario is established based on the obtained prediction error to reduce the fluctuation of the wind farm output. When modeling, the influence of the prediction error is considered in the power balance equation, and it is constructed to maximize the probability of its establishment. And then, incorporate it into the objective function. Based on this, a scheduling model is established and solved by AMFOA. Finally, an example is used to verify the accuracy of the proposed forecasting model and the economics of the scheduling model. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Due to the compact and complex internal structure of 110 kV three‐phase enclosed GIS disconnector, the voltage distribution between the contact breaks of each phase has an influence on the insulation performance of the GIS disconnector, and its internal insulation design is a difficult point to be solved. To solve this problem, this paper firstly establishes a three‐dimensional model of three‐phase enclosed GIS disconnecting switch and conducts a research on the distribution of electric field under a specific working condition, it is found that the outer corner of the static contact, the inner corner of the static arc contact, the inner corner of the outer end of the moving contact and the inner corner of the moving contact are the internal electric field concentration of the three‐phase enclosed GIS disconnector. Then, in order to further reduce the electric field strength and improve the insulation margin and performance, this paper proposes a method based on the combination of Extreme Learning Machine (ELM) and Multi‐objective Grasshopper Optimization Algorithm (MOGOA) to optimize the structural design of three‐phase enclosed GIS disconnector, and a ELM model is established, which takes the internal fillet radius of stationary arcing contact, the internal fillet radius of moving contact, the internal fillet radius of external end of dynamic and static contact, the radius of the outer corner of the two static side contacts and the opening distance of the grounding contact as the inputs, and takes the maximum electric field strength of the two static side contacts and the moving side contacts as outputs; Finally, the structural parameters are optimized by MOGOA algorithm. Compared to the pre‐optimization period, the electric field strengths of the bus bar static‐side contact, dynamic contact and static side contact of the B‐phase after optimization decreased from 20.2, 9.28 and 17.5 to 11.4, 6.65 and 11.5 kV/mm, respectively. The electric field strengths of the dynamic and static side contacts are significantly reduced, which is beneficial for improving the insulation performance of the three‐phase enclosed GIS disconnector. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

To improve the pulse width modulation (PWM) harmonic suppression effect of the three‐phase VSI‐fed PMSM system, this paper proposed a novel random switching period (RSP)‐Space Vector Pulse Width Modulation (SVPWM) technique for the three‐phase power converter. First, the proposed technique replaces the 10‐bit linear feedback shift register pseudorandom number generator (LFSR‐PRNG) with a Tiny Mersenne Twister (MT)‐PRNG to quickly generate high‐quality pseudorandom number sequences. Then, to reduce the sampling error caused by the current ripple, this paper analyzes the sampling timing under different modulation techniques. Based on the interrupted update mechanism of the Infineon AURIX‐TC264, the variable frequency sampling of the RSP‐SVPWM technique is implemented to ensure the best sampling of the motor phase current. Finally, the simulation and experimental results show that the proposed technique can effectively disperse PWM harmonic energy. Meanwhile, the RSP‐SVPWM technique based on variable sampling frequency effectively improves the phase current quality of the PMSM system. The proposed technique shows great potential for suppressing PWM harmonics in integrated PMSM systems. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The accurate estimation of the zigzag leakage flux losses (ZZLFL) caused by the slot harmonics and their interactions, which occupy a high proportion of stray losses, are of great significance in the efficiency calculation as well as the optimization design for the wet submersible induction machine (WSIM). In this paper, a two‐dimensional finite element method (FEM) is presented to separate ZZLFL into the iron losses and the eddy‐current losses. The air‐gap magnetic flux density is decomposed by the two‐dimensional fast Fourier transform at a sampling frequency of 5000 Hz. The hybrid excited virtual permanent magnet harmonic machine model is applied to reconstruct the air‐gap magnetic field and excite the stator and rotor separately. Each node harmonic iron losses are acquired through the modified Bertotti iron losses model with the consideration of high‐frequency power losses as a function of the magnetic flux density. The zigzag flux losses provided by different harmonics are obtained by subtracting the hybrid excitation losses. According to the different proportions of harmonic losses among zigzag flux losses, novel WSIM models are proposed in the paper to decrease zigzag flux losses and increase the efficiency. Adopting the same computation process, the novel models with different structures are explored and verified to improve the zigzag flux losses and power density. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

SF6 is a greenhouse gas. Finding an alternative gas for SF6 has become an urgent problem in the switch field. In order to explore the feasibility of replacing SF6 gas with dry air directly, CO2 and C4F7N/CO2 mixed gas, based on the KYN28‐12 medium voltage switchgear, the finite element method was used to solve the three‐dimensional coupled multi‐physics of the switchgear in this paper. From the angle of the temperature field and flow field, the temperature rise characteristics under different operation conditions were analyzed. The results showed that the temperature field and flow field distribution under the four gases were similar. Among them, the temperature rise of SF6 gas was the smallest, followed by the C4F7N/CO2 mixed gas, CO2 and dry air. The flow rate of SF6 gas was the lowest, about 0.11 m/s. The flow velocities of other gases were relatively close. When the switchgear was filled with the same gas, as the inflation pressure increased, the temperature rise of the switchgear decreased and the gas flow rate also dropped to a certain extent. The temperature field and flow field of the switchgear under the C4F7N/CO2 mixed gas at 0.2 Mpa were similar to those under the 0.1 Mpa SF6 gas. Under the C4F7N/CO2 mixed gas, the contact failure of the plum contact made the temperature rise of the switchgear increase overall. The maximum temperature rise point transferred to the contact failure. The temperature rise further rose with the increase of the contact failure degree. The gas flow rate also greatly increased with the failure degree elevated. From the perspective of temperature rise, the C4F7N/CO2 mixed gas has the possibility of being applied in the electrical equipment under the premise of meeting the insulation conditions. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, a new dual mode blind equalization method using neighborhood symbol‐based decision and decision‐directed (NSBD‐DD) algorithm is proposed to equalize the satellite communication signals. The proposed algorithm adopts the combined cost function to employ the advantages of symbol decision algorithm and the decision‐directed algorithm, which can further improve the universality of the proposed algorithm. Compared with the conventional blind equalization algorithm, the compensation ability of intersymbol interference and convergence speed of the proposed algorithm can be improved simultaneously. To verify the performance of the proposed algorithm, the computer simulation is performed, and the simulation results show that the residual intersymbol interference of the 64QAM signals can be decreased to −50 dB under the satellite channel, which has 30 dB lower than multi‐modulus algorithm (MMA), 26 dB lower than NSBD algorithm, and 10 dB lower than SBD algorithm. And compared with SBD algorithm, the number of iterations required for the NSBD‐DD algorithm can be decreased from 8000 iterations to 6000 iterations, which convergence speed is increased by 25%. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Due to the growing attention for the environmental impacts and power loss minimization, distributed generators (DGs) have been introduced widely into the electric power system. One of the challenges of integrating with the power system is to determine their optimal placement and sizing, which, when not respected, adversely affects the performance of the electrical network. In this paper, three multi‐objective algorithms of particle swarm optimization (PSO), variable constants (VCPSO) and genetic algorithm (GA) are adopted and implemented. The main objectives are to detect the optimum size and location of multiple DGs aiming to reduce the active power loss and improve bus voltage deviations in the distribution networks. The paper conducts a comprehensive review of the optimal size and location of the DG via systematic procedures, including definition, classifications, technologies of DGs. Then, the performances evaluation of the three optimization methods are presented and compared with other methods. The presented optimization methods are tested on the IEEE‐33 bus, 32‐line radial distribution network. Four different scenario‐based studies including base case and different number of DGs are performed to examine the accuracy of the presented algorithms. The obtained results prove that all the three algorithms are suitable for this multi‐objective optimization and VCPSO offers the best solution in terms of convergence and, and it has lowest average computation time. The performance and accuracy of the presented approaches and their improvements in the power loss and bus voltage profile are discussed and presented in detail. The obtained results show that more than 65% of active power loss reduction has been attained with the proper sizing and placement of DG systems. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper gives a novel method to design less‐conservative robust PID control systems. The partial model matching method is a design method for PID control systems. That is a method to design a control system that matches a reference model as closely as possible. This method does not guarantee robust stability of a PID control system because it is assumed that there are no uncertainties on the coefficients of the lower‐order terms of the plant. Therefore, in our previous work, a robust design method based on the partial model matching method was proposed. However, the drawback of this conventional method is that the results of stability analysis are conservative. In this paper, we aim to reduce the conservativeness caused by the conventional method. To achieve this goal, we use a robust stability analysis method based on the Cremer–Leonhard–Mikhailov criterion and the mapping theorem. Moreover, we also propose a new method to update the value of a design parameter. A numerical example shown in this paper implies that the conservativeness is reduced by the proposed method. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A new three‐phase two‐switch voltage clamping buck Power Factor Correction (PFC) is presents in this paper. The principle and equations of operations are described in detail. Based on the volt‐second balance principle of input inductance in the new converter, this paper gives the design method of the circuit's key components, with voltage and current stresses analyzed. On the basis of the theory above, a prototype with parameters of a 5 kW is designed. Problems of extremely high switch peak voltage stress in the conventional one are solved. The manufacturing cost of high power three phase rectifier has been significantly decreased. A 5 kW experimental prototype with unity power factor, 4.4% input line current THD, 200 Vdc output, and system efficiency of 96% at full load under 380 Vrms input line‐to‐line voltage has been successfully implemented. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Detecting damages on the body of the saury is important for packaging in the fisheries industry. Moreover, the appearance of a fish is important in fisheries. Fish damage detection relies on manual assembly lines, which are labor‐intensive and time‐consuming. This paper proposes a novel saury damage detection method that automatically localizes the saury body region, determines the head‐tail orientation, and detects damaged parts from the body region. We collected a saury image dataset for training and built a simple naive convolutional neural network (CNN) model without transfer learning for damage discrimination. Seven evaluation metrics, such as accuracy, F1‐score, Area under the ROC curve (AUC), and prediction time, were comprehensively considered to select the optimal parameter configuration including the number of layers, number of filters, filter size, and input image size. We also utilized the transfer learning of eight pretrained CNN models to classify the saury into two categories for damage discrimination. Inception‐v3 and ResNet‐101 achieved the highest accuracy of 98.2% for damage discrimination. Through extensive experiments and discussion of the results, this paper presents clear guidance for choosing pretrained networks for transfer learning in damage detection tasks. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Two low‐voltage cables, insulated with flame‐retardant ethylene‐propylene‐diene rubber (FR‐EPDM), were removed after being laid in nuclear power plants for many years. We measured the leakage currents flowing through their insulators and found that the resistivity of cable insulation is higher in the two harvested cables than in a similar but new and unused FR‐EPDM one. The reason for this result is discussed in this paper based on a comparison of the leakage currents between new and gamma‐ray irradiated FR‐EPDM sheets. The discussion is continued by referring to our previous papers on mechanical properties and infrared absorption spectra of similar new and gamma‐ray irradiated FR‐EPDM sheets. As a result, it has been clarified that additives such as pigments contained in the cable insulators are likely to act as a source of charge carriers. In addition, the cable insulators became hardened by the long‐term aging in an environment of about 60 °C, which made the ionic conduction difficult and the insulation resistivity higher. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]