23 July 2026, Volume 45 Issue 7

    

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Specialist's Forum
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  Research progress and applications of high-temperature superconducting motors

  LIU Xin, LIU Yanjun, TANG Yiming, SHENG Yuzhong, WANG Qiuliang

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 1-22. https://doi.org/10.12067/ATEEE2505027

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  Superconducting materials possess excellent properties such as zero resistance, diamagnetism, and the electron tunneling effect. By using them as the materials for the rotor or stator coils of motors, high-temperature superconducting motors (HTS motors) can be fabricated. Relying on their technical advantages of high efficiency, low loss, and high-power density, HTS motors have demonstrated important engineering application values in the fields of megawatt-level power equipment, such as large-scale wind turbine generator systems, marine vessel electric propulsion, and electric aviation propulsion systems. This paper first provides an overview of the application scenarios of HTS motors, including HTS motors, HTS generators, HTS linear motors, HTS motors with special structures, and HTS synchronous condensers, and introduces the research progress of HTS motors both at home and abroad. Secondly, it elaborates and summarizes the key technologies of HTS motors, including high-temperature superconducting materials, cryogenic cooling technology, and quench protection. Finally, it explores the feasible optimization approaches of HTS motors in aspects such as the motor structure, superconducting materials, cooling technology, and quench protection mechanism.
Treatise and Report
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  Dynamic evaluation of energy losses in all-vanadium liquid-flow battery energy storage modules applied to household photovoltaic-storage systems

  LI Jianbin, SONG Zhengxiang

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 23-34. https://doi.org/10.12067/ATEEE2504024

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  Household all vanadium flow battery energy storage systems for photovoltaic-storage applications are difficult to assess the energy loss economics due to the low average system efficiency under operations such as intermittent power supply, hot standby, and multiple applications, and the unbalanced distribution of energy consumption. This paper proposes a dynamic assessment method for energy loss of household all vanadium batteries, which includes loss calculation methods for flow resistance, battery polarization, ion crossing, branch current and auxiliary thermal management. The paper takes 10 kW vanadium flow battery equipment as the test research object to analyze the distribution of each energy loss parameter of the battery over time for multiple charging and discharging experiments in the constant-voltage, constant-power charging and discharging modes under photovoltaic access and to establish a loss assessment. The probability distribution function of the energy loss rate and SOC/SOD is established to evaluate the energy loss interval during the long charge/discharge cycle of the household system. The results show that the energy loss of the household system varies linearly with SOC between 266% and 402%, and the flow resistance loss accounts for 6%~7% of the interval in the long cycle operation, with the largest value near SOC=25%; the battery polarization loss accounts for 8%~9% of the interval, with the largest value near SOC=85%; the ionic cross-loss accounts for 1%~2% of the interval, with the largest value at the end of the charging and discharging period when SOC=75%; and the branch circuit loss accounts for 1%~2% of the interval. The loss value is largest near SOC=75% at the end of charging and discharging period; the branch circuit loss accounts for 4%~5% of the interval, and the loss value is largest near SOC=85%; and the loss of auxiliary thermal management equipment accounts for 5%~6% of the interval in the high temperature environment in summer, and the loss value is largest near SOC=25%. This study provides experimental guidance for the operation optimization of the optical storage and charging multi-scenario vanadium flow battery energy storage system, and the experimental data provide effective support for the improvement of system parameter design.
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  Temperature rise characteristics and contact temperature calculation method of 252 kV single-break vacuum interrupter

  HAO Jian, SHAO Ziqi, HE Xiaorui, LIU Wei, ZHANG Yanchao, FENG Weigang

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 35-46. https://doi.org/10.12067/ATEEE2502001

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  252 kV single-break vacuum circuit breaker is known as the “crown jewel” in the field of environmentally friendly high-voltage switchgear. The vacuum interrupter is the core component of vacuum circuit breaker, and mastering the temperature distribution characteristics of vacuum interrupter is crucial for its structural optimization design and safe operation. This paper carries out the research on the temperature rise characteristics of 252 kV single-break vacuum interrupter and its contact temperature calculation method, based on the electromagnetic-temperature simulation method to study the correlation between the dynamic temperature rise of vacuum interrupter contacts and the load current and ambient temperature, and verify the validity of the simulation method and the contact temperature calculation method. The results show that the highest temperature of the interrupter chamber occurs between the movable and static contact pieces, and the temperature rise of the contact pieces is 70 K at 11 times the rated current. The contact temperature of the interrupter shows a saturation-type exponential law increasing trend with the growth of the through-current time, and the ambient temperature mainly affects the size of the contact steady state temperature value. This paper proposes a mathematical model to quantitatively calculate the contact temperature based on load current and ambient temperature, and the error between the measured and simulated temperatures of the 252 kV vacuum interrupter conductive rods and the main shielding cover key point temperatures rise obtained based on the high-current temperature rise test platform is less than 2 K. This paper provides a reference for grasping the temperature characteristics of the vacuum interrupter chamber of the 252 kV environmentally friendly switch.
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  Study on discharge characteristics of typical defects in cable termination silicone oil at varying moisture contents

  REN Hailong, ZHAO Su, ZHOU Yanhao, YIN Yi

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 47-58. https://doi.org/10.12067/ATEEE2507039

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  Moisture ingress is one of the key factors that leads to the degradation of silicone oil performance and induces partial discharge, posing a serious threat to the operational safety of power equipment. This study investigates the discharge behavior of silicone oil under different moisture content conditions by controlling exposure durations (0, 1, 2, 3, and 5 days) to regulate its water content. A systematic analysis is conducted on how varying moisture levels influence the partial discharge characteristics of typical insulation defects within cable terminals. Two types of discharge models (needle-plate and surface discharge structures) are constructed to simulate typical defects. Partial discharge signals are collected and analyzed to quantify discharge magnitude, frequency, and phase-resolved characteristics. The results show that silicone oil becomes saturated with moisture after approximately five days of exposure, with increased moisture content significantly intensifying partial discharge activity. Under the needle-plate defect model, the discharge magnitude at the same voltage level increased by 478%, 586%, and 546% compared to new oil; under the surface defect model, the increases were 226%, 379%, and 518%, respectively. Furthermore, under identical conditions, the maximum discharge quantity induced by the surface defect was at least 23 times greater than that of the needle-plate defect.
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  Transient synchronous stability analysis of grid-forming energy storage converter during asymmetrical grid fault

  GAO Yongqiang, ZHAO Linsheng, MEI Yong, HE Wenwen, LI Jialu, YAO Jun, TAO Wenwei, ZHANG Jie

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 59-69. https://doi.org/10.12067/ATEEE2502010

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  Compared with the traditional grid-following energy storage converter (GFL-ESC), the grid-forming energy storage converter (GFM-ESC) can provide voltage and frequency support for the power grid, which can significantly improve the system stability under short-circuit fault scenarios, and has attracted wide attention in recent years. Consequently, GFM-ESC have attracted great attention in recent years. When an asymmetrical short circuit fault occurs in the power grid, GFM-ESC system will experience transient instability, but there are few researches on this problem. In this paper, the GFM-ESC system is investigated under asymmetrical short-circuit fault conditions. In addition, a dual-loop control structure model of positive- and negative-sequence voltage and current is established for the GFM-ESC system under asymmetrical short-circuit fault conditions considering the sequential switching characteristics. Based on the symmetrical component method, the composite sequence network of the system is obtained under asymmetrical short-circuit fault conditions, and positive- and negative-sequence power-angle characteristic curves are analyzed. The influence law of system parameters on the transient synchronous stability of positive- and negative-sequence systems is quantitatively analyzed through the equal area criterion. Finally, the correctness of the theoretical analysis is verified by hardware-in-the-loop experiments.
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  Research on transient stability of grid-forming voltage source converters considering reactive power loop

  WANG Sue, QU Kang, HAO Pengfei, WANG Ziting

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 70-85. https://doi.org/10.12067/ATEEE2601027

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  In view of the transient stability problem of grid-forming voltage-source converters (GFM-VSCs), most existing studies neglect the influence of the reactive power loop, leading to relatively conservative analytical results. This paper takes grid-forming converters with consideration of the reactive power loop as the research object, and investigates their transient stability and parameter-dependent transient stability boundaries. Firstly, a nonlinear power-angle mathematical model incorporating the reactive power loop is established. The transient instability mechanism of the system and the influence trends of control parameters are qualitatively analyzed using the power-angle curve and the phase-plane method. Then, the equivalent linearization method in nonlinear vibration analysis is adopted to derive the analytical solution of the nonlinear power-angle differential equation. The influence laws of control parameters on the system transient stability are quantitatively analyzed, and the transient stability boundaries and feasible ranges of control parameters are determined. Finally, simulations and hardware-in-the-loop experiments are conducted to verify the accuracy and effectiveness of the proposed analytical solution and stability boundaries, thereby providing a reference for the selection of control parameters.
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  An improved model predictive control strategy for grid-connected inverters based on parameter identification and current reconstruction

  HE Wu, XUE Changkui, SHEN Wenting, WANG Jie, TAN Haoyu, MIAO Shihong

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 86-100. https://doi.org/10.12067/ATEEE2512014

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  To address the issues encountered in conventional self-synchronization control of grid-tied inverters during low-voltage ride-through (LVRT)—namely, large transient inrush caused by high grid impedance and low short-circuit ratio (SCR), high distortion of asymmetrical fault currents, and transient inrush upon fault clearance—A model-predictive direct-power control (MPDPC) strategy based on parameter identification, power disturbance compensation and current reconstruction is proposed. First, considering practical inductance mismatch, an inverter impedance model is established, and the estimated filter inductance is updated via the least-squares method to refine inverter parameters, thereby mitigating model errors. Second, based on the accurately identified inductance and Euler forward discretization of the voltage control equation, a predicted current is reconstructed by leveraging the temporal coupling between voltage and current vectors to achieve concurrent suppression of active and reactive power oscillations. Then, current limiting, dynamic reactive-power support, and multi-function power-quality conditioning are integrated to coordinate the trade-offs between grid-side current harmonic mitigation and output power fluctuation damping. Simulations indicate that, under symmetrical and asymmetrical grid faults with varying voltage sag depths, the proposed strategy suppresses power oscillations and mitigates transient inrush within 001 s, and reduces the three-phase total harmonic distortion (THD) by ≥35%. The proposed method effectively suppresses transient inrush and reduces current distortion, exhibiting strong robustness and fast, smooth transient behavior, thereby enhancing the output power quality of the grid-tied inverter.
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  Multivariate operating parameter prediction of generators based on a Bayesian optimization for multi-output Gaussian process

  ZHANG Zhou, WANG Di, JU Zhenhao, LI Mingyin, ZHANG Yan, WANG Ying, PAN Xinyu

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 101-113. https://doi.org/10.12067/ATEEE2503065

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  To predict short-, medium- and long-term sensor data of operating alternators, this paper proposes a Bayesian optimized multi-output Gaussian process (MOGP)-based framework. The sensor data of alternators is composed of three parts: the global trend caused by wear and tear of components and degradation, the random noise induced by sensor-measurement uncertainty, and the local trend influenced by environmental and anthropogenic random factors. The proposed method captures the global degradation trend via the prior mean function, followed by reconstructing the residuals between the values of the mean function and measurements by temporal low-rank decomposition to remove noise term. Then, the MOGP captures the correlation between multiple sensor signals via the task covariance function and the local temporal correlation via the input covariance function. To avoid the model overfitting on historical data, Bayesian optimization is used to estimate model parameters. Finally, the proposed method outperforms benchmarks in predicting short-, medium- and long-term sensor data of two alternators.
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  Study on aging failure mechanism of transformer bushing seals under thermal-compressive factors

  LIANG Wei, LA Yuan, YUAN Yao, CAI Dexuan, YIN Fanghui, WANG Liming

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 114-125. https://doi.org/10.12067/ATEEE2508040

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  Aging failure of transformer bushing seals under thermal oxidation and compression is a key cause of oil leakage accidents. To explore their aging mechanism, multi-layer compression tests were conducted on NBR and FKM seals under varied temperatures and compression ratios. These tests combined measurements of mass change and compression set for life prediction, along with analyses including FTIR and SEM. Results indicate that thermal oxidation exacerbates NBR aging in multiple aspects. At low temperatures, aging is dominated by cross-linking, primarily driven by the volatilization of plasticizers and antioxidants, with macroscopic property degradation proceeding slowly. At high temperatures, the mass loss and compression set of the sealing ring increase rapidly, severe thermo-oxidative aging occurs, chain scission and crosslinking take place extensively, and the internal structure of the rubber is damaged. Compression, when coupled with thermal oxidation, significantly affects elasticity changes. Both excessively low and high compression ratios reduce molecular chain flexibility, which is detrimental to maintaining elasticity. A 25% compression ratio is optimal as it slows stress relaxation and ensures better sealing reliability. Its predicted service life at 40 ℃ reaches 1772 years, far longer than the 471 years at 20% and 553 years at 30% compression ratios. During aging, the compressed surface of the seal is less exposed to air, resulting in a lower degree of aging. FKM exhibits insignificant aging characteristics due to its superior chemical stability.
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  Noise suppression method for partial discharge in converter transformers based on pulse waveform adaptive recognition

  LIN Haofan, LAI Zekai, JIN Yongtao, SHAO Xianjun, HUA Xiaochang, BAI Tong, MU Haibao, ZHANG Guanjun

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 126-134. https://doi.org/10.12067/ATEEE2502011

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  For suppressing complex noise interference in wideband pulse current detection of partial discharge (PD) in converter transformer, a denoising method based on pulse waveform adaptive recognition is proposed. First, a 10 MHz high-pass filter is used to remove the impact of periodic narrowband interference on the zero-crossing count of the waveform. Then, windowing is applied to the signal, and windows without pulse waveforms are set to zero based on the instantaneous zero-crossing density. Next, pulse waveforms are extracted from the original signal according to the start and end times of each pulse, forming a pulse array. Finally, adaptive recognition is performed on each pulse waveform based on waveform characteristics to filter out partial discharge signals. The proposed algorithm effectively suppresses white noise, periodic narrowband interference, and random pulse interference. It significantly improves the similarity between the denoised signal and the original PD signal, resulting in a higher signal-to-noise ratio and noise reduction ratio.
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  Design and optimization of wireless charging coupling mechanism for oil downhole water controller

  LI Yang, WAN Lingchang, ZHOU Bin, ZHAI Yujie, ZHANG Chong, QIN Hanlin

  Advanced Technology of Electrical Engineering and Energy. 2026, 45(7): 135-144. https://doi.org/10.12067/ATEEE2507043

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  In the special environment of oil downhole, wireless power transfer suffers from large eddy current losses, and coils inevitably experience misalignment, resulting in low transmission efficiency of downhole wireless charging, which makes it difficult to meet the wireless charging requirements of downhole oil water controllers. To address this issue, this paper designs a wireless charging coupling mechanism suitable for downhole installation environments, aiming to overcome the impact of the downhole electromagnetic environment and coil misalignment on transmission performance. First, based on modeling using equivalent circuit theory, the relationship between transmission efficiency and coil parameters is derived, along with the main factors that affect the transmission efficiency of the coupling mechanism in the complex downhole electromagnetic environment. Then, through finite element simulation, a comparative analysis is conducted on the impact of different parameters of the coupling coils and electromagnetic shielding structures on transmission efficiency, followed by parameter design and optimization. Finally, a downhole wireless charging experimental system is built for verification. The results show that the coupling mechanism can effectively wirelessly charge the water controllers, with a maximum transmission efficiency of 9427%. Even when the longitudinal misalignment of the transmitting and receiving coils reaches 70mm (with a misalignment ratio of 5385%), the coupling mechanism still maintains a transmission efficiency of 85% or higher.