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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]

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]

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 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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

This paper examines an inertial response control for wind turbines in order to provide the system inertia decreased by the integration of asynchronous variable renewable energy sources. Specifically, an application of the temporal power surge, a strategy by which the output of a wind turbine can be temporarily increased with releasing the kinetic energy stored in the rotating mass, was proposed to address significant frequency drops in a microgrid. Since the rotational speed of turbine has to be decreased by this approach, it is necessary to further reduce the wind power output to recover the rotational speed after the temporal power surge. This drawback may lead to a second frequency drop, and it is effective to intentionally increase the rotational speed beforehand to mitigate this negative effect. However, this measure causes output curtailment under normal operating conditions. Hence, a determination method of the rotational speed considering the output curtailment was proposed in this paper to facilitate frequency regulation through the temporal power surge. The proposed methods for adjusting rotational speed are evaluated and their effectiveness were verified through numerical simulations. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a designed experimental simulation scheme for dynamic air gap eccentricity (DAGE) faults in permanent magnet synchronous generator (PMSG), along with the testing of their electromechanical characteristics. Unlike previous studies, this paper proposes and applies an experimental device setting scheme that enables accurate and convenient calibration of the DAGE fault degree, offering a novel solution for practical DAGE simulation. The experimental unit measures the electromechanical characteristics of the PMSG before and after the DAGE fault, taking into account the influence of load. The mechanical parameter considered is the stator vibration, while the electrical parameter is the circulating current parallel branches (CCPB) inside the stator winding. The characteristic frequencies of stator vibration and CCPB under the DAGE fault are analyzed based on the experimental results and verified through theoretical calculations and finite element analysis (FEA). The findings demonstrate the effectiveness of the proposed DAGE experimental device. Moreover, DAGE failure increases the strength of stator vibration and introduces new frequency components, namely fr and 2f ± fr. Under normal operation, the PMSG exhibits no CCPB. However, DAGE faults cause CCPB with frequency components of f ± fr. Moreover, the severity of the fault degree positively correlates with larger root‐mean‐square (RMS) values and characteristic frequency amplitudes of stator vibration and CCPB. Furthermore, the amplitude of stator vibration and CCPB decreases with increasing load. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The increasing penetration rate of distributed energy brings more complex problems of voltage quality, safety and stability to the distribution network. A single optimal configuration of reactive power or energy storage is difficult to meet the increasingly diversified needs of modern power grids. This paper proposes a configuration strategy combining energy storage and reactive power to meet the needs of new energy distribution networks in terms of active power regulation and reactive power compensation, and to achieve tradeoff optimization in flexibility, voltage quality and economy, so as to adapt to the influence of new energy with different permeability. Firstly, the safety and stability evaluation system of distribution network is established with the target of flexibility demand and reactive power demand. Secondly, considering the coupling of planning layer and operation layer, a two‐layer model of energy‐reactive power optimization is established. After that, the gray wolf algorithm is used to solve the model, which enhances the global space exploration ability and reduces the possibility of falling into the local optimal. Finally, the improved IEEE33 node power distribution system is used for simulation test to verify the rationality and effectiveness of this scheme. The simulation results show that the scheme proposed in this paper can effectively improve the economy, security and stability of the distribution network, and can obtain an optimal configuration scheme with multi‐objective considerations under different new energy penetration rates. © 2023 Institute of Electrical Engineer of Japan and 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]

Abstract in order to study the torque ripple of permanent magnet synchronous motor for electric vehicle, the method of modular poles instead of single pole is adopted to reduce the torque ripple. The modular poles consist of three kinds of permanent magnets with different remanence and are arranged in a sinusoidal distribution. The pole arc length and position of each magnetic pole are calculated according to the cutting area of sinusoidal air gap flux density wave. By changing the cutting area of sinusoidal air gap flux density wave, the optimal pole arc coefficient of each permanent magnet was determined, and the magnet pole combination with the smallest torque ripple value is obtained. The results show that the sine degree of back electromotive force is improved obviously, the cogging torque is decreased greatly, and the motor with modular poles has obvious effect on torque ripple suppression. The torque of the motor with different kinds of magnetic pole combination is more stable than that of the motor with the same kind of magnetic pole combination. In this paper, the method of using modular poles instead of single pole to reduce torque ripple is of positive significance, which provides a reference for the subsequent performance optimization of electric vehicle motor. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a strategy for direct‐driving a turbine with an external rotor high‐speed permanent magnet motor. It is used to improve the large footprint, low efficiency, high maintenance costs, and high vibration risk of turbines. Combining the characteristics of the working conditions of pipeline gas transmission, this paper takes a 200 kW, 10 000 rpm external rotor high‐speed permanent magnet motor as an example. This paper analyzes the eddy current losses in the rotor due to the armature magnetomotive force generated by the stator fundamental and harmonic currents. To reduce eddy current losses in permanent magnets, a circumferentially segmented pole structure is proposed for theoretical comparison and FEA with common surface‐mounted pole structures under different loads and work angles. The results confirm that the circumferentially segmented pole can effectively reduce the eddy current loss of the permanent magnet rotor. The effect of variations in the pole arc coefficient on eddy current losses in permanent magnets is also analyzed. Finally, the temperature field simulation of the motor is carried out under consideration of wind mill losses. By setting up three comparison groups with different conditions, this paper analyses the influence of the temperature and flow rate of the gas on the temperature rise and heat dissipation of the motor in a high‐temperature gas environment. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A novel sliding mode observer for speed estimation in sensorless induction motor drives at zero and low speed is proposed in this paper. First, aiming at the poor stability when the induction motor runs at low speed, analyze the reasons of the poor stability and a new feedback gains design method is proposed. Second, for the problem of ignored flux error in speed estimation which cause speed error at low speed, a new compensation method is put forward, which can improve the accuracy of speed estimation in the dynamic and steady state of the system. Meanwhile, a continuous function is given which can replace sign, to restrain the chattering problem of sliding mode observer. Detailed simulation results are given showing the operation at zero and low speed, the results prove the effectiveness of the proposed sliding mode observer. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Electric field distribution is a determinant factor of air gap breakdown voltage. This paper defined an effective electric field zone between the sphere gaps for feature extraction, and 29 parameters were extracted from this zone to reflect the electric field distribution. A data mining model was established by back propagation neural network (BPNN) for sphere gap breakdown voltage prediction, taking the electric field features as inputs. The maximum information coefficient (MIC) method was used to select features strongly correlated to the breakdown voltage, and a multi‐strategy improved salp swarm algorithm (ISSA) was applied to optimize the BPNN parameters to enhance the prediction performance. The standard sphere gaps provided in IEC 60052 were taken as training set and test set, which were divided according to the electric field nonuniform coefficients. The breakdown voltage prediction results of test sample sphere gaps demonstrate good agreements with the experimental values. With input features selected by the MIC method, the ISSA optimized BPNN model has a mean absolute percentage error of only 0.83% and a maximum relative error of 5.86%. By constructing the nonlinear mapping relationship between the effective electric field features and the insulation strength, this study provides a new approach to predict air gap breakdown voltage. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Model predictive control has been wildly used in the modern power electronic converter with the advantages of the multi‐objective optimization, no additional modulator is required and small grid current harmonic. However, the switching operation is not constant and higher sampling frequency must be required. A novel direct power control using model predictive control (DPC‐MPC) strategy is presented in this paper, which achieve the optimal vector prediction scheme with constant switching frequency operation. The calculation process is greatly simplified due to the optimal voltage vector generated directly, then, it applied to the control of a three‐phase three‐level T‐type grid converter. A cost function is first built to balance the neutral‐point‐potential voltage. After then, the cost function is updated by considering the delay caused by the calculation, sampling and gate driver. Finally, a comprehensive comparative study with the conventional DPC‐MPC strategy is introduced to verify the superiority of the presented DPC‐MPC. The simulation and experimental results show that the steady and the transient performance of the grid current with the proposed DPC‐MPC control strategy are effectively improved. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents an evolutional topology optimization of electric machines, which works like gradient‐based local search methods, based on the covariance matrix adaptation evolution strategy (CMA‐ES). The present method enables to improve the performance of initial machine shapes without computing the deviation of the objectives. Moreover, for the resultant shapes obtained by the present topology optimization method, this paper also presents a sensitivity analysis method based on the normal distribution which is used to seek for solutions in CMA‐ES. Using the present sensitivity analysis method, important parts which contribute to improve a machine characteristic can be visualized. The two present methods are applied to the optimization problem of a synchronous reluctance motor. It is shown that initial rotor shapes defined by designers can effectively be modified using the present optimization method. Moreover, it is also shown that the sensitivity distributions with respect to some machine characteristics are visualized by the present method. In addition, each machine characteristic is respectively improved by modifying the machine shape according to the respective sensitivities. © 2022 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]

This paper compares the machine learning algorithm‐based prediction methods for the traction characteristics in linear traction induction motors operating at common working conditions, i.e. different slip and running velocity, with a symmetric or asymmetric secondary. These models provide a method for obtaining the dynamic characteristics in the motor that considers nonlinear effects. First, some analytical results for the prototype machine under different working conditions is calculated. Second, classification and feature extraction of traction characteristics results including thrust, transversal and vertical forces is made according to the different slip, running speed and lateral secondary displacement, and the results set is divided into training sets and test sets. Third, the prediction model established by different machine learning algorithms are analyzed and compared in principle. These algorithms in this paper mainly contain: artificial neural networks (ANNs), linear regression (LR), symbolic regression using GP, k‐Nearest Neighbour (kNN), random forests (RFRs). The machine learning algorithm‐based prediction methods are trained with the training set, and then the verified with the test set. Finally, this paper discusses the most optimal model for predicting traction characteristics. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The low‐speed and high‐torque modular fault‐tolerant permanent magnet motor has the strong fault‐tolerant ability, and can make the motor output torque act on the load directly, and the system has the highest transmission efficiency, which is especially suitable for ship propulsion. In the electric ship direct‐drive propulsion system, the motor is the core of the power system. Because the motor is directly connected with the load, the intermediate buffer mechanism is canceled, so the smooth operation of the motor is put forward to higher requirements. Especially in some fault‐tolerant operations, the unbalanced radial force generated by the asymmetric operation may cause the motor to vibrate greatly, which will reduce the operational life of the motor and even bring new faults. In serious cases, the whole transmission system will be damaged. Therefore, it is necessary to study the vibration of the fault‐tolerant motor under different operating conditions. In this paper, the module combined stator fault‐tolerant permanent magnetic synchronous motor for ship direct‐drive propulsion is taken as the research object. Based on the Maxwell tensor method, the radial force wave expressions of the motor during regular operation and fault‐tolerant operation are derived, and the harmonic order and frequency, which have a significant influence on vibration are summarized. The radial force of the motor under different operating conditions with different control strategies is calculated by the finite element method, and the harmonic components are analyzed by the two‐dimensional Fourier transform. On this basis, the vibration of the motor and the mechanical strength of the rotor support frame are analyzed. The research results of this paper provide some reference for the subsequent vibration reduction strategies of fault‐tolerant motors. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A spherical image has a full field of view. Using spherical images can estimate camera pose more accurately than conventional perspective images. It is known that a sphere can be quasi‐uniform sampled by dividing a geodesic dome repeatedly; it results in a representation with rotational invariance approximately. Based on this fact, in this paper we proposed a method of estimating a spherical camera pose based on the geodesic‐dome‐division‐based discrete spherical image representation by modifying the conventional perspective‐image‐oriented convolutional neural network, called PoseNet. First, a spherical image is represented as a geodesic‐dome‐division‐based discrete spherical image. Then, to cope with the six‐connectivity of the pixels of a geodesic‐dome‐division‐based discrete spherical image using the conventional convolutional neural network framework, the discrete spherical image is flattened as a connected five parallelograms and resampled as an eight‐connectivity image. Consequently, via the comparative experiments, it is found that the geodesic‐dome‐division‐based discrete spherical image representation approach can achieve a better result of camera pose estimation than equirectangular image and CubeMap representations. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a single‐stage DC/AC converter for the implementation of a high‐power‐density onboard AC inverter. The proposed circuit integrates a non‐isolated DC/AC converter into an isolated DC/DC converter using only simple duty control and phase‐shift modulation, which reduces the required number of semiconductor switches. Additionally, a coupling inductor and center‐tapped transformer can be shared by the two converter functions, so they can be integrated without additional circuit components. This paper describes the operating principles of the proposed converter and design solutions are extracted using multi‐objective optimization to achieve optimal performance in terms of power density and efficiency. Based on the design solution extracted through optimization, a prototype with a volume of 0.5 l was fabricated and a power density of 3.0 kW/l with an efficiency of 94.7% was achieved at a rated power of 1.5 kW. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In induction motor no‐load test, the no‐load losses usually include the stator copper loss, iron loss, the friction, and the windage losse, and the stray loss, and the rotor aluminum loss often is ignored. In this paper, a new method that separates the rotor aluminum loss from the no‐load losses is mentioned. Although, in IEEE Standard 112 and IEC34‐2, the rotor aluminum loss is neglected in no‐load test. However, in proposed method, the rotor aluminum loss is considered as an important part of the no‐load loss. Therefore, this paper intends to develop a new testing method to obtain the rotor aluminum loss under no‐load condition. In this case, six induction motors of the same kind (3 kW, four‐poles) are chosen to carry out no‐load and ideal no‐load tests. Through the comparative analysis of experimental data, the no‐load rotor aluminum loss accounts for about 13.4% of the no‐load loss, and the test approach can also explain that this part loss is not generated by higher harmonics. Based on these results, this paper demonstrates that the rotor contact resistance has great influence for the no‐load rotor aluminum loss, and a rotor resistance analysis model with rotor contact resistance is proposed. Final, the proposed method offers the possibility of taking measures on rotor resistance to improve motor efficiency. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper introduces the concept of intermittently connected sensor networks where sensors are sleep most of time and become active randomly and rarely. In the networks, packet collision probability and power consumption can be reduced. Meanwhile, the delivery delay increases with the use of the low activation values. In this paper, we design the energy‐efficient intermittently connected sensor networks, considering this trade‐off of activation control. We first provide the algorithm that computes the optimal packet forwarding rule achieving the minimum delivery delay, which can be calculated using the activation rates. We then propose the activation rate control methods, which control the activation rates of the sensors based on the density of the sensors and/or the number of wake‐ups of sensors having relay packets. By doing this, we can improve the delay performance, while suppressing the increase in the packet collision probability and the power consumption of sensors. Through simulation experiments, we demonstrate the effectiveness of our activation control methods in the intermittently connected sensor networks. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The high‐temperature electric‐actuated valve widely adopts the split structure, and the valve stem drives the opening and closing of the valve after passing through the high‐temperature packing and sealing structure. However, the transmission chain is too long, which cannot meet the pursuit of small volume and lightweight in the nuclear industry. In this paper, a novel integrated structure of high‐temperature direct drive electric‐actuated valve canned permanent magnet synchronous motor (DDEAV‐CPMSM) is proposed. The structure omits the dynamic sealing structure composed of stuffing box, pressure plate and pressure sleeve, as well as the transmission structure of gears and couplings, and the reliability is significantly improved. This paper focuses on the calculation of the dimension parameters, thermal load design, and electromagnetic vibration of DDEAV‐CPMSM, and compares it with the integrated structure of the induction motor to explore the optimal topology of the high‐temperature electric‐actuated valve. Aiming at the problem of serious heat generation in limited space, it is difficult to simulate the running time of high‐temperature valve. Based on the magneto‐thermal coupling method, a 3D temperature field model considering high‐temperature heat source, canned sleeve eddy current loss, and hydraulic friction loss is established. The steady‐state temperature distribution of the system at high temperature and the transient temperature change law of valve opening and closing are analyzed, and the minimum time of secondary start‐up and the maximum running time under fault conditions are further studied, to provide a theoretical basis for the application of DDEAV‐CPMSM. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Fractional slot concentrated winding (FSCW) is a kind of winding structure with few‐slots/coils multi‐poles. FSCW has the potential value of high torque density due to its short end‐winding and high slot fill ratio and is widely used in low‐speed direct‐drive application situations. However, compared with integral slot winding (ISW), the back EMF coefficient of FSCW is smaller, which leads to smaller output torque under the same condition. To improve the back EMF coefficient of FSCW, equidirectional toroidal winding (ETW) is proposed and applied to the dual rotor slotless axial flux permanent magnet motor (AFPM), in which the unit structure is three slots/coils two poles, and the ideal back EMF coefficient is the same as that of ISW. In this paper, firstly, the structure of ETW is introduced and its operating principle is analyzed. Then, compared with the AFPM with ISW, the open circuit and load characteristics of the AFPM with ETW under two conditions of the same wire gauge and the same coil width are analyzed respectively. The back EMF coefficient and output torque of ETW‐AFPM are similar to that of ISW‐AFPM under the same coil width. The back EMF coefficient and output torque of ETW‐AFPM are a little lower than that of ISW‐AFPM under the same wire gauge. Finally, the experimental results also validate the feasibility of AFPM with ETW and the correctness of the analysis results. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

It is of prime importance to realize the integration of variable renewable energy sources (VRE) for sustainable energy society. The frequency regulation becomes an important issue in the power system with more VRE integration due to uncertain output fluctuation of VRE generators. Another issue caused by VRE integration is congestion management in transmission network, and locational marginal price (LMP) has been applied in some power networks to avoid the congestion issue based on economic mechanism. The congestion issue has to be considered in the balancing control to cope with frequency fluctuation because more balancing power could be needed due to the VRE integration. Hence, in this paper, the application of LMP to the balancing power market in terms of capacity procurement was proposed. A part of transmission capacity was assigned to the balancing control and the location of the control reserves was given with LMP. The effectiveness of the proposed method was verified through numerical simulations based on a combined model for both the frequency regulation and the power flow calculation. It was shown that the congestion issue was properly mitigated with keeping the frequency fluctuation by using the proposed method. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this article, a community integrated energy system (CIES) coupled with electricity, gas and heat is investigated, which integrates with renewable energies such as photovoltaic and wind turbine. The main goal is to seek an optimal scheduling scheme, including reducing the operating costs and fully exploiting the demand response potential. Firstly, given the structure of CIES, the system equipment and loads are modeled and analyzed. Moreover, considering the user controllable degree, a comprehensive user satisfaction method is established based on the combination of subjective weight and objective weight method. This paper concerns the user controllable degree in the process of flexible load optimization so that some amounts of loads are transferred from peak periods to off‐peak periods to flatten the load curve. Three cases studies in the article show the influence of user controllable degree and satisfaction on CIES. Finally, the system model is solved using CPLEX solver in MATLAB optimization software. The results show that the operating costs and environmental costs are reduced by 9.31% and 3.24% due to the presence of user controllable degree and satisfaction. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to improve the reliability of the traditional doubly salient electro‐magnetic generators (DSEG) and realize the isolation of interphase magnetic circuit, a U‐shaped rotor stator excitation generator (UR‐SEG) for vehicle applications is proposed in this paper. The machine has the interphase physical isolation and short flux path structure because of the U‐shaped rotors. According to the theoretical analysis of the fault‐tolerant characteristics of this UR‐SEG, the characteristic of the phase electromotive force (EMF) of the UR‐SEG completely overlaps with the EMF of front and rear phase in the entire power generation stage is revealed. Then the flux linkage, EMF, output voltage of both normal and faulty states are comparative investigated using the two‐dimensional finite element method (FEM). The output characteristics of the normal state and four faulty states of the machine with different exciting currents are researched, and the influence rules of fault on output characteristics are obtained. Finally, the outstanding fault‐tolerant characteristics of the UR‐SEG were verified by the experimental results. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Transformer is a key equipment for constructing power system, and its safe and stable operation is the basis of power system. In order to solve the problems of difficult identification and low detection accuracy of transformer winding at operating state, in this paper, a diagnosis method based on digital twinning technique for transformer winding failure is proposed. Firstly a digital twin transformer model with high simulation degree based on transformer entities was built, and then multiple physical field simulation were used to deduce the information change of oil tank surface vibration information of digital twin transformer under different working conditions, various winding failures. Here, the vibration signal on oil tank is effectively decomposed to extract the feature vector by independent component analysis method and wavelet packet transform, which in turn is based on neural network algorithm to learn and diagnose the failure signal of winding. In order to test the accuracy and feasibility of the method, the diagnostic test of oil tank vibration signal detection of health and fault transformer is carried out on an experimental prototype of transformer with 110 kV, and the diagnostic results show that this method can diagnose the problems occurred in transformer windings with high efficiency and accuracy. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to ensure the train operation safety, it is necessary to analysis the transient response of track circuit in complex electromagnetic environment. According to the distribution characteristics of transmission lines in traction electric network and the structure of ZPW‐2000 jointless track circuit, the multiconductor transmission lines model of the traction electric network combined with the track circuit is established. The model cannot be calculated directly due to the presence of parallel or terminated nonlinear lumped elements in the track circuit. For this problem, the new analytical method is proposed, which is based on finite difference time domain (FDTD) method to solve the transmission line part, Thevenin's theorem with state variable method to solve the equations of the terminated nonlinear track circuit. The solution equation of multiconductor transmission line system is obtained by combining the two parts. The relevant parameters of the model can be calculated by finite element method. In ATP‐EMTP, the simulation results verify the correctness of the expression. In addition, through the transient response experiment of track circuit, it is confirmed that the transmission characteristics of transient signal on rail are consistent with the calculation results in this paper. Finally, the influence of signal frequency, ballast resistance on track surface voltage, and the influence of interline coupling voltage by the conductivity (σ) and the permittivity (ε) are studied. It provides theoretical reference for the anti‐interference analysis of track circuits. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Path planning is one of the fundamental issues in the research field of robot. In the last decades, Rapidly‐exploring Random Tree star (RRT*) was one of the chosen path planner for robot with its probabilistically complete. In this paper, an improved bidirectional RRT* path planner for robot is proposed (Bi‐RRT*), which has planned path with safety and smoothly guarantee. The main contributions of this paper include, firstly, combining the backtracking idea of the Quick‐RRT algorithm with the greedy search strategy of the RRT‐Connect algorithm, which can reduce the path cost and improve the operation efficiency of the algorithm. Second, in order to further reduce the running time of the algorithm, a new collision detection algorithm based on cross‐product is proposed to replace the conventional collision detection strategy. To ensure the quality of the path, two post‐processing strategies, path optimization strategy and path smoothing strategy, are proposed. Path optimization strategy is based on triangle inequality, and two optimization methods are proposed to effectively reduce the path cost. The path smoothing strategy based on the Bezier curve improves the continuity of a smooth arc and is better applied to path smoothing. Simulation results for both virtual and real environments show the advantages of combining Quick‐RRT and RRT‐Connect and verify the effectiveness of the proposed collision detection algorithm. Compared with similar algorithms, the proposed Bi‐RRT algorithm has higher operational efficiency, smaller path cost, smoother planned paths, and improved path quality. © 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]