The Proceedings of the 19th Annual Conference of China Electrotechnical Society

To solve the problem of poor steady-state performance of the duty cycle model predictive current control (DC-MPCC) for permanent magnet synchronous motor (PMSM) and the problem of a large amount of calculation of the dual vector model predictive current control (DV-MPCC), the improved dual vector model predictive current control (IDV-MPCC) is proposed. All the voltage vectors are divided into two vector sets according to the error of all the candidate voltage vectors corresponding to the predictive current and the reference current, and one voltage vector is selected from each of the two vector sets for each control period. According to the simulation results, the steady-state performance of IDV-MPCC at low speed is similar to that of DC-MPCC and DV-MPCC. The q-axis current ripple and torque ripple of IDV-MPCC are obviously improved when the speed increases, and the amount of calculation decreases compared with DV-MPCC. On this basis, a control strategy is proposed to switch between DC-MPCC and IDV-MPCC according to the speed, which can maintain a good steady-state performance in a wide range of speed changes while reducing the amount of calculation at low speed.

The pseudospark switch is widely used in the field of repetitive pulse power technology due to its advantages of high withstand voltage, large current and low jitter. With the development of laser technology, laser triggered pseudospark switch (BLT) has become a current research hotspot, which is very beneficial to solve the complex problems of electrical isolation, anti-interference and synchronization in large pulsed power devices. Because the high energy density focused laser is often used in BLT, it is of great research value to explore the damage characteristics of switch under different factors and obtain the optimal trigger mode. In this paper, the simulation model of laser ablation of metal based on the simplified two temperature model is constructed, and the influence of laser energy and metal type on the shape of ablation pit and the influence factors of electrode life are explored. The simulation results show that with the increase of laser energy, the depth and radius of the ablation pit increase, and basically meet the linear relationship. When the same laser irradiates different kinds of metals, the depth and radius of the ablation pit are quite different. The metal with low absorption rate, high density and high evaporation latent heat has shallower ablation depth, and the service life of the corresponding switch is longer.

With advancements in science and technology, traditional linear control methods have shorts in meeting the demands of high-frequency, high-power, and high-precision control. Consequently, the application of high-performance nonlinear control methods in power electronics has emerged as a critical concern. The paper proposed a hybrid sliding mode control for bidirectional Buck-Boost converter. In Buck mode, a state observer combined with hysteresis loop sliding mode control reduces switching frequency and sensor dependency. In Boost mode, non-singular terminal sliding mode control addresses the singular phenomena in sliding mode control, compensating for the non-minimum phase disadvantages of the Boost converter. Simulation results confirm that the proposed control method enhances both dynamic and steady-state characteristics. Furthermore, the control strategy is easy to adjust parameters and implementation, offering a novel approach for power electronic converter design and application.

The large-scale integration of renewable energy sources poses significant challenges to the stable operation of existing power systems. Flexible interconnection devices can facilitate local consumption of renewable energy and help alleviate these challenges through dynamic power flow regulation. However, current flexible AC interconnection solutions often face difficulties in balancing reliability with cost-effectiveness in engineering applications. To address this issue, this paper introduces a novel direct series flexible interconnection topology that eliminates the need for a series transformer. The equivalent circuit for this topology is developed, and its principles for steady-state power flow control and transient fault ride-through are analyzed. A theoretical model is derived based on the equivalent circuit analysis, from which a phase-separated steady-state control strategy is proposed. In addition, a graded transient control strategy featuring three levels of protection—current limiting, blocking, and tripping—is introduced. The proposed control strategies are validated through experimental data from the Huzhou Flexible AC Interconnection Demonstration Project, demonstrating their effectiveness during minor voltage dips and severe faults.

The calculation of no-load performance of transformer core usually adopts statistical method based on past data or whole modeling simulation, ignoring the influence of core joints. If the core is simplified as a whole, the actual electromagnetic characteristics of the joints and the decisive influence of the joints on the no-load loss and no-load current of the core cannot be displayed. Although multi-stack model can calculate a limited number of silicon steel sheets, but it is costly and difficult to be used for the actual core. In this paper, a single stack cyclical model with the even periodic boundary is proposed, and compares the no-load performance of three types of joints, through theoretical analysis and experimental verification, this model has high accuracy.

The dynamic response characteristics of PCB spark gaps under transient pulses are investigated using the field and circuit synergistic method. Firstly, the spark gap discharge tube is taken as the research object, and its measurement system under TLP pulses of different voltage levels is built, and its response voltage and current characteristics are obtained. A three-dimensional full-wave model of the measurement structure containing a spark PCB gap is built in CST, in which a SPICE netlist is used to describe the time-varying arc-resistance model when the gap breaks down, and then a voltage-controlled switch is used to control the startup of the Toepler’s time-varying arc-resistance model in the field-circuit co-simulation of CST to solve the problem of the time lag of the spark gap breakdown. The simulation results of the response voltage and current are consistent with the actual measurements, and the time-dependent distribution of the surface current on the PCB is obtained by the field-circuit co-simulation. Finally, the proposed field-circuit cooperative modeling method is successfully applied to the simulation of spark gap discharge on PCBs, and the results are in good agreement with the tests.

The traditional LLC resonant converter is analyzed by using the fundamental analysis method (FHA), which ignores the influence of high-order harmonics on the circuit and results in significant gain errors when deviating from the resonant point. In this paper, the time-domain analysis method (TDA) is used to draw the gain surface of the LLC resonant converter, as well as the surface of the inductance ratio and quality factor. A group of resonant parameters are designed. At the same time, a magnetic integration technology is adopted to integrate the resonant inductor and transformer into one magnetic core. The optimal selection of loss and volume for the integrated magnetic components is carried out, and shielding layer technology is used to reduce the influence of parasitic parameters on the primary and secondary sides of the converter at high frequencies. According to the finite element simulation results, the integrated magnetic components reduces losses by 33% compared to discrete magnetic components, and the power density increases by 43.8%. Finally, a LLC resonant converter with a power of 800 W, a switching frequency of 1 MHz, and a voltage of 400 V/48 V is built, and the rationality of the resonant parameters and integrated magnetic component design is verified through experimental testing results.

This manuscript presents an advanced sensorless control strategy for Permanent Magnet Synchronous Motors (PMSMs) designed to address the challenges posed by cross-saturation effects and magnetic field distortions. The research focuses on fractional slot concentrated winding interior PMSMs, which are particularly prone to inductance parameter variations due to magnetic saturation and cross-coupling. To tackle these issues, a comprehensive analysis of the inductance parameter impact on position estimation error is conducted. Using finite element analysis (FEA), we carefully simulate the motor’s inductance, considering magnetic saturation and cross-coupling effects. These results are used in a sliding mode observer (SMO) for sensorless control, which is tuned with a phase-locked loop (PLL) to improve position estimation accuracy throughout the motor’s operating range. The low-speed startup is efficiently managed through an I/F initiation method, transitioning to the improved SMO and PLL for medium to high-speed operations, thereby achieving precise sensorless control. Extensive simulations substantiate the method’s feasibility and robust performance.

The Doubly Salient Electromagnetic Motor (DSEM) has a promising application prospect in fields such as new energy vehicles. However, the field windings of DSEM brings high copper loss, and traditional converter topologies and control methods limit the improvement of motor efficiency. In this paper, to improve the efficiency of a four-phase 8/6 pole DSEM, a current coordinated control strategy based on five-leg converter is proposed. This strategy achieves coordinated control of the DSEM positive and negative phase currents and field current by controlling the five-leg switches. Based on the working principles of the converter, the relationship between phase current, field current, and average electromagnetic torque is established through magnetic co-energy. The minimum copper loss current combination is obtained using the Lagrange multiplier method, and a speed closed-loop control is established. Simulation results show that compared with the conventional symmetrical current control, the motor efficiency increases 2.8%, and the system efficiency increases to 80.3%. The proposed control strategy reduces copper loss, and improves motor efficiency and system efficiency without using more power switches.

Compared with traditional permanent magnet synchronous machines (PMSM), the Interior Permanent Magnet Synchronous Machine with Unequal Tooth Widths (UNETIPMSM) offers advantages such as high torque density and good fault tolerance. However, this also leads to an increase in torque ripple. To suppress the torque ripple of UNETIPMSM, a method of stator/rotor auxiliary slots was studied. The mechanism of torque ripple generation in permanent magnet synchronous motors was analyzed. A finite model of a 10-pole/12-slot motor is established to perform electromagnetic simulation. Three types of auxiliary slots are proposed, with notching the armature tooth, fault-tolerant tooth, and both the armature and fault-tolerant tooth. Additionally, the effects of the slot width and depth of rotor auxiliary slots on torque ripple are investigated, and three auxiliary slot structures are compared. The results indicate that appropriately designed auxiliary slots on the stator and rotor can effectively reduce torque ripple while maintaining the motor’s performance.

In order to improve the dynamic response performance, reduce power consumption, and increase thrust consistency within stroke, the effects of key dimensions on the magnetic flux density and thrust force for both axial and radial magnetized voice coil motors (VCMs) are analyzed with the aid of finite element method. According to the simulation results, the optimal designs of the two types can be obtained pertinently, which ensures the rationality and accelerates the development cycles. By comparing the dynamic response, heating, and efficiency, it is concluded that the radial magnetized structure exhibits better performances under the specified requirements. On this basis, the magnetic field characteristics and static thrust force of the prototype are measured, verifying the reliability and feasibility of the finite element method. The proposed optimization idea can provide some reference for the future VCM design.

Diagnosing faults in wind turbine bearings under variable operating conditions is challenging due to signal fluctuations, noise interference, and limited model generalization. This paper proposes an intelligent diagnostic approach that combines noise-resilient feature extraction with optimized neural network learning to capture fault-sensitive features and adapt effectively to varying conditions. Experimental results validate the method’s consistent diagnostic performance, underscoring its practical value and applicability in complex operational environments.

During the electromagnetic pulse welding (EMPW) process of tubes, the high-speed collision between outer tube and inner tube is easy to cause the shrinkage of inner tube, and it is difficult to form metallurgical bonding. In this work, a dual-coil EMPW method based on the synergies gained from compression coil and expansion coil was proposed, and a three-dimensional simulation model of EMPW process of aluminum alloy tube (outer tube) and stainless-steel tube (inner tube) with coupling the electrical-magnetic-mechanical was established. The distribution pattern of magnetic flux density, induced eddy current, Lorentz force and the movement process of tubes with the effect of dual-coil were analyzed. The results showed that the maximum induced eddy current densities of aluminum alloy and stainless-steel tubes were 7.54 × 1010 A/m3 and 3.31 × 1010 A/m3, respectively. The maximum Lorentz force densities of aluminum alloy and stainless-steel tubes were 8.31 × 1011 N/m3 and 6.59 × 1011 N/m3, respectively. Besides, the maximum collision velocity of the aluminum alloy tube was 772 m/s, while that of the stainless-steel tube was 166 m/s. As the collision velocity decreased and the collision angle increased, the collision velocity and angle match the welding window, indicating that the method is feasible.

When the large-capacity turbine generator is operating, there is a large amount of copper and iron losses on the stator, which is seriously heated, may lead to local high temperature and even burn accidents. It seriously affects the safe of the generator. Therefore, this paper takes a 350 MW turbine generator cooled by water-hydrogen as an example to conduct thermal study on the key components of the stator. Firstly, the global fluid network model, the 2D electromagnetic field-path coupling model and the 3D half-tooth and half-groove full-axial fluid-structure interaction model of the stator is established based on the mathematical equations. Secondly, the inlet and outlet conditions of hydrogen and water, the heat flow density of each part are solved. The temperature of stator is calculated and measured to verify the correctness of the results. Then, the temperature distribution of key components such as cooling water, windings, and main insulation in the stator are studied. Finally, the multi-temperature peak-to-valley value of windings, and large multi-direction temperature difference of main insulation are described. The conclusion of this paper provides theoretical support for optimizing the temperature distribution of the stator and preventing the damage of the main insulation performance.

When a high-current transformer is operated as a generator transformer, the winding current can reach tens of kiloamperes, resulting in increased losses that elevate the winding temperature. The poor thermal conductivity of the insulating paperboard results in localized overheating of the windings, which accelerates the aging of the insulation. In order to improve the thermal conductivity of the insulating paperboard, the insulating paperboard was modified through doping with nano-SiO2. The impact of varying nano-SiO2 concentrations on the thermal conductivity of the nano-SiO2-modified insulating paperboard was then investigated through molecular dynamics simulation, to develop a predictive model of the modified insulating paperboard. A three-dimensional model of a 500 kV power transformer was constructed, and the material parameters of the modified paperboard were incorporated into the simulation analysis of the transformer's magnetic field, flow field, and temperature field. The findings indicate that the thermal conductivity of the material is enhanced by 16.8% at a doping content of 7% of nano-SiO2. Additionally, the maximum temperature on the modified insulating paperboard is 95.1 ℃, which is 2.5 ℃ lower than that of the unmodified paperboard. These results substantiate the exceptional heat dissipation properties of the modified paperboard.

With the advantages of high energy density, low self-discharge rate, and no pollution, lithium batteries have gradually developed into one of the important choices in the energy storage industry. The low reliability, high complexity and low accuracy of the battery life assessment model are important factors restricting its application in large-scale energy storage power stations and electric vehicles. In this paper, based on the cyclic aging test data of lithium iron phosphate storage batteries, a residual life prediction method for lithium batteries that incorporates multiple health factors is summarized by analyzing the relationship between the charging current, voltage, and temperature profiles and the battery capacity degradation during the battery aging process. The method combines the time variation corresponding to the same current during charging, the time variation corresponding to the same voltage during discharging, and the moment movement characteristics corresponding to the temperature peak, and utilizes Pearson correlation coefficient and Spearman's rank correlation coefficient to study the linear correlation relationship between the multiple factors and the battery life degradation, and combines with the empirical model of linear regression to achieve a more accurate prediction of the battery life.

SF6 or SF6/N2 insulated circuit breakers are widely used in high-voltage power grids, especially ultra-high voltage grids, due to their advantages such as high dielectric strength across the breaker contacts, excellent breaking performance, long maintenance intervals, and small footprint. In recent years, the phenomenon of SF6 decomposition under arc action has received significant research attention. However, there has been no systematic review of the research progress on this topic in the literature so far. This paper reviews the decomposition mechanism of SF6 under arc action, the characteristics and key influencing factors of gas decomposition, and its applications. The high temperature of the arc can cause deep decomposition of SF6, N2, and other gases, forming highly reactive atoms such as sulfur and fluorine or sulfur fluorides, which can further generate a variety of gas decomposition products such as SOF2, SO2, and solid metal fluorides. These processes are influenced by factors such as arc energy, gas mixture ratio, breaking current, electrode materials, and test methods. Detecting SF6 decomposition products holds promise for effectively assessing the condition of circuit breakers. It is necessary to continue research on condition monitoring methods and applications in the future.

To fully utilize the advantages of different energy in electro-hydrogen hybrid energy system, this study delves into the working principles of various energy sources, establishing mechanism models for proton exchange membrane fuel cells (PEMFC) and proton exchange membrane electrolyzers (PEMEC). Furthermore, an electro-hydrogen hybrid energy system is constructed, including a PEMEC module, a lithium battery module, a photovoltaic power generation system module, four DC/DC converter modules. Subsequently, an energy management strategy based on equivalent energy consumption minimization for electro-hydrogen hybrid energy system is proposed to achieve efficient utilization of different energy sources. Finally, simulation experiments were conducted on the MATLAB/Simulink simulation platform, proving the effectiveness and feasibility of the proposed method. The experimental results demonstrate that, compared with the traditional energy management strategy based on finite state machines, the proposed method can more reasonably distribute the energy flow of different energy sources, reducing the total system energy consumption by a total of 17.09%.

In order to solve the problem of stable power supply and condition monitoring of railroad wagon vehicles, to further enhance the transportation efficiency and reduce operating costs. In this paper, a self-powered control and monitoring system for smart trucks is developed, and a corresponding test platform is built. The test results show that, the axle end power generation device can reach 110 W of low-speed high-power power generation and structural components without significant temperature rise. The redundant design of the power control circuit improves the stability of the power supply of each type of power supply for the condition monitoring components. The speed signal processing mechanism can provide stable electrical signals to reduce the response time of air braking, enhance braking performance and improve the reliability of operational safety, and the visualization of monitoring data can facilitate condition repair to reduce operating costs.

Current research lacks an optimized control level prediction method to ensure optimal motor power output during train operation. This paper, grounded in the operation of asynchronous motors in high-speed trains, designs a dynamic level control model integrated into the train's traction/braking unit closed-loop control system. Leveraging system identification, the level prediction model integrates linear models within the complete information space with unknown nonlinear dynamic models. To mitigate the impact of missing data on model accuracy, this paper introduces an enhanced bidirectional Long Short-Term Memory (Bi-LSTM) neural network model to interpolate missing data and employs a combination of Particle Swarm Optimization (PSO) and Improved Grey Wolf Optimization (IGWO) algorithms for selecting hyperparameters related to the neural network. To enhance the accuracy of predicting unknown nonlinear systems, this paper proposes a Bi-LSTM/LSTM model switching prediction algorithm based on autocorrelation coefficients. Finally, the effectiveness of the prediction method is validated using actual data from the CRH380B train.

Aiming at the traditional Maximum Power Point Tracking (MPPT) technique, which is easy to fall into local optimum and fail under complex shading conditions, and the MPPT control technique based on meta-heuristic algorithm has the disadvantages of slow convergence speed and large steady-state power oscillation, an Improve Grey Wolf Optimization Algorithm (IGWO) and Incremental Conductance Method (INC) are combined in a two-layer MPPT control algorithm model. In the upper layer, the traditional Grey Wolf Optimization Algorithm (GWO) is improved by using the nonlinear convergence factor and differential evolutionary algorithm to quickly approximate the global maximum power point of the P-U, and INC is introduced in the late convergence stage of the lower layer to perform an accurate search of the MPP. Finally, by comparing with the improved cuckoo algorithm (ICS), it is verified that this hybrid MPPT control algorithm takes into account the speed and accuracy of tracking, and it is robust in complex situations.

In order to solve the problems of low power factor and poor ability to resist grid voltage drop of single-phase AC input inverter, and obtain higher reliability, a single-phase AC input Z-source inverter is proposed for high-performance control of permanent magnet synchronous motor drive system under all working conditions. The working principle of ac input Z-source inverter is analyzed. Based on the traditional DC input Z-source inverter, a single-phase AC input Z-source inverter is proposed, the design principle and control method are given, an experimental prototype is built, and a complete experiment is carried out on the system. The experimental results verify the feasibility of the system.

The power electronic transformer, based on modern power devices, achieves multi-stage power conversion and energy management, playing a significant role in the new power system. Its insulation material, polyimide, is prone to partial discharge (PD) under high-frequency electrical stress, leading to accelerated insulation aging. To investigate the influence mechanism of high-frequency voltage frequency and amplitude on PD characteristics, a high-frequency partial discharge experimental platform was established to study the variations in PD parameters under different voltage frequencies (10 kHz–40 kHz) and amplitudes (2 kV–4 kV). The experimental results indicate that the discharge current amplitude is proportional to the applied voltage amplitude, and with an increase in voltage frequency, the discharge current amplitude shows an initial increase followed by a decrease, forming a “turning point” phenomenon. Considering the trend of polyimide's dielectric constant decreasing with increasing voltage frequency, a modified plasma PD numerical model was constructed to describe the spatiotemporal evolution of particles during PD and the generation pattern of the oxidative byproduct, ozone. The analysis of the impact of applied voltage amplitude and frequency on the discharge current amplitude revealed that the mismatch between the charge dissipation rate due to the dielectric constant and the applied voltage frequency is the reason for the “turning point” in discharge current amplitude observed at higher voltage frequencies.

Controlled Source Radio Frequency Geomagnetic Method (CSRMT) is an active source electrical exploration method based on geomagnetic (MT) technology in geophysical science. A movable artificial excitation source is built to detect the changes of underground electric and magnetic fields and calculate the electrical properties of underground structures. The construction of a stable excitation system is an important part of the CSRMT design, but the inverter circuit composed of power devices will produce high voltage overshoot during the turn-on and turn-off process, which not only affects the waveform quality but also leads to the damage of the circuit devices due to exceeding the voltage withstand level, therefore, setting up buffer circuits is an effective way to mitigate the voltage overshoot to ensure the normal operation of the circuit. First of all, the causes of voltage overshoot in the switching process are analyzed by taking MOSFET as an example, selecting a discharge-blocking RCD buffer circuit and analyzing the working principle. Through simulation and experiment, it is shown that the discharge-blocking RCD buffer circuits have strong voltage overshoot mitigation and suppression ability, low loss, and can be used in high-frequency inverter circuit excitation system.

Transcranial magnetic-acoustic stimulation (TMAS) is a new non-invasive brain neuromodulation technique based on the development of traditional neuromodulation techniques. This technique applies ultrasound and magnetic field to the neural tissues together, and realizes the modulation of specific brain regions by generating induction current. With the advantages of modulation area focusing, controllable, deep stimulation depth, and non-invasiveness, it is expected to achieve clinical applications. In this paper, a magnetic-acoustic stimulation method based on pulsed magnetic field is proposed, which uses a coil to generate a pulsed magnetic field instead of a permanent magnet. This reduces the size and weight of the magnet, and is easy to operate. It is also conducive to more flexible adjustment of the value of the magnetic flux density, which increases the adjustable range of the value of the current density obtained in the target area. It helps to better achieve the effect of magnetic-acoustic stimulation as well.

The auxiliary beam provides a solution to enhance the mechanical properties of the connector by modifying the structure of the spring plate. In this paper, an on-board small connector is taken as the research object. Firstly, the mathematical model between the contact normal force and contact deformation of the terminal with rolling tongue cantilever beam structure is constructed, and the size and material parameters of the terminal were substituted to calculate the contact normal force of 0.43N. Then, the insertion and extraction simulation of the connector terminal is carried out with ANSYS simulation software, and the contact normal force is obtained to be about 0.40N, with a relative error of 7.5% compared to the theoretical calculation result. However, the contact normal force does not meet the design requirements. To solve this problem, this paper adds an auxiliary beam between the metal shell of the socket and the main beam of the spring plate, and ANSYS simulation is performed and analyzed. According to the simulation results, the addition of the auxiliary beam increases the contact normal force to 2.66N, and the insertion and extraction force reaches about 1N. The auxiliary beam effectively improves the contact normal force and insertion and extraction force of the connector terminals, but it also poses a potential problem of making the auxiliary beam stress exceed the yield limit of the material.

Glowing contact in low voltage electric circuit is mostly caused by poor electrical contact, which is easy to cause fire. The existing electrical detection method is based on the voltage of glowing contact, while the location of glowing contact is often unknown, causing detection difficulties. An experimental platform for glowing contact is built, and the reasons of high-frequency component are explained. A time-frequency domain detection method for glowing contact based on the current of the parallel filter capacitor on the load side is proposed. The high-frequency components generated by glowing contact in the capacitive current are detected. The characteristic frequency bands of glowing contact are analyzed to be 5–15 kHz and 20 kHz ~ 30 kHz. The electrical signal characteristics of glowing contact under different wire cross-sectional areas, wire materials and loop current amplitudes are studied. The amplitude of high-frequency component is proportional to the cross-sectional areas of the wire, which is conducive to the detection of glowing contact. The temperature of glowing contact is proportional to loop current amplitude, which gradually approaches the boiling point of cuprous oxide. The high-frequency component generated by brass wires are richer than those generated by copper wires, but the power spectrum of the characteristic frequency band decreases, which are not conducive to the detection of glowing contact.

With the complex structure of distribution network, the efficiency of manual phase measurement is quite low. To reduce the time of interruption of power supply, a remote on-line phase measurement system is designed, and an assessment method for phase measurement operation is proposed. Firstly, collect secondary voltage of potential transformer or charged indicator; secondly, combine the voltage with time scale by phase measuring equipment witch is installed in DTU; and finally, transmit the voltage waveform to the main station over the distribution automation system to analyse whether the phase is the same. Based on the operating time and accuracy of the phase measurement system, the connection stability and phase measurement quality is analyzed by the main station. The results show that the remote on-line phase measurement system can obtain the phase difference in a short time, the result of phase measurement is stable and reliable, work efficiency has been significantly improved.

Gas Insulated Switchgear (GIS) as one of the key equipments in substation, its safe and reliable operation has always been a hot spot of power system research.The partial discharge phenomenon of GIS is the main cause of equipment failure, so it is of vital significance to perceive its partial discharge effectively to ensure the stable operation of the system. This paper firstly discusses the detection method of partial discharge of GIS based on single physical sensing technology such as electric, optical, acoustic, chemical, etc. According to the current status of research at home and abroad, it is known that the sensing of single parameter still has certain limitations. On this basis, it comprehensively analyses the current multi-parameter joint sensing methods, and explains that multi-parameter sensing technology is the future development direction, which can provide detailed data support and scientific basis, and help to improve the monitoring efficiency and security of the power system.

In recent years, the high-voltage XLPE cable buffer layer ablation problem has been a common occurrence. Currently, the usual option is to directly replace the original cable, but this will result in large financial losses. The paper focuses on buffer layer ablation treatment technology and investigates the efficacy of the cable buffer layer ablation inhibitor. Firstly, the effect of concentrated leakage current on buffer layer ablation was studied, and the principle of inhibitor action was explained from the perspective of ablation mechanism. At the same time, requirements for the physicochemical properties of inhibitors were proposed; Secondly, A cable ablation simulation experimental platform has been established to demonstrate the effectiveness of inhibitor; Thirdly, based on the typical structure of 110 kV cables, a finite element simulation model was established to analyze the electrical characteristics before and after adding inhibitors to the cables. The results showed that after adding inhibitors, the field strength and temperature of the buffer layer became uniform, and local hot spots were eliminated; Finally, the effectiveness of the proposed method was verified through experiments, which showed that the inhibitor can eliminate local heating in the buffer layer.

In order to increase the efficiency of energy utilization and improve the operation economy of the integrated energy system, this paper constructs the optimal scheduling model of the electric-gas-hydrogen integrated energy system, including the power sub-network, the natural gas network and the electrical coupling part. Firstly, from the basic structure of the system, the energy conversion relationship between each subsystem is analyzed, and the mathematical model of each subsystem is established. Then, the optimal scheduling model is established to minimize the objective function including the cost of electricity purchase, the cost of gas purchase and the cost of operation and maintenance of each equipment. Finally, the effectiveness of the relevant schemes is tested by using the example of IEEE33-node system and 20-node natural gas system, which shows that the schemes that take into account pressure energy generation and hydrogen blending of natural gas pipeline network have good economy, and improve the absorption capacity of renewable energy in the integrated energy system to a certain extent.

The plasma melting furnace is an important device for radioactive waste plasma melting treatment technology, and its overall furnace structure has an important influence on the temperature distribution, which is also the key to improve the thermal efficiency of the system and the quality of radioactive waste treatment. In this paper, the finite element software COMSOL is used to carry out three-dimensional steady-state numerical simulation of the plasma melting furnace, focusing on the impact of the furnace structure on the waste treatment capacity. Through the establishment of mathematical models, combined with fluid dynamics theory and multi-physical field coupling nodes to calculate the interaction between the physical fields, the temperature field and velocity field inside the furnace body are calculated, and the calculated results are compared with the experimental data, and the relative error is 11.62%. And compare and analyze the influence of different structures on the temperature field and material handling effect, to provide theoretical guidance for the optimization of furnace structure design and thermal efficiency improvement.

When an aircraft suffers a lightning strike, the cables are coupled with overvoltages by the pulsed electromagnetic field generated from the lightning current, probably resulting in damage towards the electrical and electronic equipment connected to these cables. In this paper, four typical lightning strike paths are planned for experimental study by simulating and calculating the lightning attachment points of aircraft. A full-scale aircraft model, 12.8 m in length, 12.3 m in width, and 4.4 m in height, is assembled. Artificial simulated lightning strike tests are conducted to investigate the lightning coupling effects on aircraft cables with different lightning strike paths and cable types. Results show that the degree of lightning coupling increases with the parallelism between the spatial arrangement of the cables and the lightning strike path. When both ends of the cables are connected to 50-Ω loads, and other conditions are kept constant (e.g., same cable length, no shielding, etc.), the type of cable does not significantly affect the transient voltage. Additionally, transient voltage waveforms at the cable terminal loads show no noticeable difference under the same excitation current. These findings elucidate the variation patterns of transient voltage at cable terminal loads under different lightning strike paths and cable types, and might provide a theoretical basis for the design of lightning interference protection for airborne cables.

The research on using photovoltaic and energy storage in smart grids to support rail transit traction power supply has far-reaching scientific research significance and practical value. Based on the bidirectional conversion traction power supply device, this paper directly integrated the photovoltaic storage distributed power generation system into the DC traction network, which not only reduced the number of traction substation planning and design, but also saved the cost of the original photovoltaic storage inverter device, and achieved more efficient vehicle braking regeneration energy utilization. At the same time, this paper analyzed the application of photovoltaic storage system in new rail transit traction power supply, explored its technical advantages and implementation solutions, and ensured that the system can operate stably for a long time under photovoltaic and load fluctuations. Research showed that photovoltaic energy storage system can effectively improve the stability and reliability of rail transit power supply system, reduce energy consumption and carbon emissions, and achieve green and sustainable development of rail transit system.

As research on large language models (LLMs) progresses, LLM-based evaluation has surfaced as an economical and viable substitute for human assessments in the comparison of an expanding array of models. Rather than concentrating exclusively on theoretical evaluation techniques, such as the indicator system, this article advocates for a pragmatic strategy by developing and deploying an LLM evaluation platform that utilizes the big data framework, Hadoop, to manage extensive evaluation datasets and streamline the cleansing of various data sources. Additionally, the proposed system accommodates tailored algorithms and rules, allowing for the export of results to designated databases, which significantly alleviates the burden on data cleaning personnel. Building on the system architecture and theoretical validation outlined in this paper, the author has established a robust LLM evaluation platform grounded in big data infrastructure. The standard data cleaning procedure illustrates that data cleansing can be effectively executed, and user interactions can be optimized in accordance with the theoretical framework proposed herein.

This article proposes a control strategy for flexible participation of energy storage systems in power grid peak shaving, in response to the severe problems faced by high penetration areas of new energy, such as wind and solar power curtailment, peak shaving, and rotating backup configuration. This strategy considers the coordination and control of fast and slow peak shaving resources for battery state of charge. While ensuring the stability of system operations, it prioritizes the voluntary participation of energy storage with faster response speed in grid peak shaving. At the same time, it reasonably arranges the adjustment timing coordination of fast and slow speed units to improve the quality of system peak shaving services.

The analysis of transformer oil temperature data is essential for monitoring the condition of their internal insulation and for evaluating the operational reliability of transformers, which is vital for effective power transformation. Nevertheless, the positioning of the oil temperature sensor within a complex environment renders it vulnerable to malfunctions, resulting in the production of inaccurate monitoring data. Such anomalies can profoundly affect the evaluation of the transformer's condition. Consequently, after carefully investigating different categories of abnormal sensor data, a detection methodology for transformer oil temperature sensor data utilizing PEDformer is introduced. The proposed model has shown proficiency in recognizing a diverse array of abnormalities within extensive oil temperature monitoring datasets. The high precision and efficacy have also been corroborated through extensive testing with various transformer oil temperature monitoring data.

Due to the non-stationary and non-linear characteristics of arc fault currents, detecting series arc faults in low-voltage systems poses significant challenges. Discrete Wavelet Transform (DWT) is an algorithm with notable advantages in processing transient signals. Combining DWT with Machine Learning (ML) has significantly improved the accuracy of series arc fault detection, attracting widespread attention in the academic community. However, wavelet transforms involve numerous parameters to be determined, and there is limited research on how to select appropriate wavelet parameters. This paper proposes a Particle Swarm Optimization (PSO)-driven wavelet decomposition scheme and feature selection method for series arc faults (PSO-WDFS). The method first classifies the load based on the fundamental waveform of the signal, then uses PSO to automatically select suitable wavelet parameters and feature subsets from over 40,000 combinations for each category, and finally constructs an artificial neural network with the selected features to achieve accurate arc fault detection. Experimental results on the test dataset show that this method effectively discriminates between arc faults and normal currents, achieving an accuracy of over 97% in datasets with mixed load types.

This paper studies the optimal design method of aeronautical DC/DC converter with wide voltage input. The topology of the converter is Buck + LLC-DCX. The converter works at high frequency, so the GaN power devices with better performance are selected. The magnetic components and related circuit parameters of the two-stage converter are optimized. The negative coupling inductor is adopted in the interleaved buck to make the flux distribution more uniform and increase the equivalent inductance of the converter. For the second stage LLC, design the excitation inductor considering the nonlinear output capacitance of GaN firstly. Then integrate the matrix transformer to reduce the height of the transformer, and further proposes the design scheme of low-height transformer with open air gap in the middle, which makes the flux distribution of the transformer more uniform, the core loss and winding loss are reduced. Finally, a 200–400 V input, 28 V/1kW output prototype is developed, and the experimental waveform and test data are given. The peak efficiency reaches 96.08%.

In this paper, the properties of polydimethylsiloxane (PDMS), trialumina (ATH), and silicon dioxide (SiO2), as well as the properties of their composite rubber, were investigated. The findings indicate that silicone rubber exhibits a specific water absorption rate, ranging from 0.1% to 0.7%. Through gravimetric and thermogravimetric analysis, the “breathing” phenomenon of silicone rubber was observed, wherein the material absorbs water upon heating and releases it upon cooling. The dielectric response of silicone rubber with various formulations was examined using dielectric spectroscopy. The results demonstrate that the dielectric properties of silicone rubber are influenced by the presence of inorganic fillers (such as ATH and SiO2) and organic fillers (such as silicone oil) within the formulation. Notably, after water absorption, the dielectric spectrum of silicone rubber exhibited a significant shift, with the relaxation peak moving to lower frequencies and a marked increase in the dielectric loss tangent. The paper also underscores that hydrophobic pretreatment of hydrophilic fillers can mitigate water absorption and reduce the retention of water molecules within silicone rubber.

The common mode (CM) noise of a Boost converter is mainly caused by the displacement current and parasitic capacitance passing through high dv/dt nodes in the circuit, which may cause electromagnetic interference to surrounding equipment. In order to reduce the size of EMI filters, measures need to be taken to reduce CM noise of the Boost converter. This paper analyzes the suppression methods of CM noise in Boost converters, mainly summarizing the working principles of various measures from the perspective of main circuit topology optimization, and simulating and analyzing the key parameters that affect CM noise suppression effect, providing reference for the further development and practical application of suppression methods.

Power quality enhancement, energy losses reduction as well as transmission efficiency improvement are pivotal for the sustainable expansion of power distribution networks. Generally, reactive power optimization is essential for the stable and efficient functioning of distribution networks. Regarding this issue, in this study the impacts of reactive power load, transformers, generators, capacitors, and static var compensators are comprehensively evaluated. For this purpose, an improved genetic algorithm is adopted, by refining key components such as the coding framework, initial population, and adaptation mechanism, along with crossover and mutation strategies. The IEEE-118 bus system is used for simulation experiments. The results confirm the merits of the applied improved genetic algorithm.

Brushless DC motors (BLDCM) are widely used in the industrial field due to their high power density and good speed regulation performance. Optimization design of a BLDCM requires consideration of multiple objectives such as torque, mass, efficiency and etc., which makes it a multi-objective optimization (MOO) problem. In this paper, a novel MOO algorithm based on Sparrow Search Algorithm (SSA) is proposed. Firstly, a Pareto solution selection mechanism is put forward, which transforms the SSA, originally a single objective optimization algorithm, into a MOO algorithm, then to address the issue of traditional SSA being prone to local optima, Latin hypercube sampling and opposition-based learning strategies are introduced in the population initialization process, and Gaussian mutation is later used to modify the population update mechanism of SSA. Performance of the proposed algorithm is verified using ZDT series test functions. Finally, it is applied to an optimal design problem of a typical BLDCM. Numerical results demonstrate the correctness and effectiveness of the proposed algorithm.

Leakage faults are common occurrence in low-voltage power grids, and residual current device (RCD) are the primary protective device against such faults. However, in practical applications, frequent tripping of RCD has become a focal issue, highlighting the conflict between power supply safety and reliability, causing to the deactivation of many RCDs. To address this problem, the paper analyzes both the impedance characteristics of low-voltage distribution network and the operating principles of RCD protection. The study shows that the current low-voltage distribution network exhibits complex RLC impedance characteristics, comprising resistive, inductive, and capacitive components. Under the influence of various disturbances, the residual current in the distribution network may include high-amplitude, wide-frequency, and short-duration impact harmonic current, which affect the correct operation of RCD. To adapt to the current distribution network conditions, this paper proposes adding a second-order Butterworth low-pass filter to the residual current signal processing stage of the RCD to eliminate the influence of harmonic current. Simulation results show that the improved RCD can significantly enhance its resistance to impact harmonic residual current, reducing false trips and thereby improving power supply safety and reliability.

With the large-scale development of new energy and the rapid growth of electric vehicles, battery energy storage systems can effectively promote the consumption of renewable energy and provide a cost recovery pathway for retired power batteries. However, most current research mainly focuses on using reconfigurable battery packs to flexibly switch the connection between batteries, in order to ensure the safe application of retired power batteries in energy storage systems, while neglecting further improvement of the overall energy storage life. Therefore, using the state of health (SOH) attenuation model, this article proposes a relationship function that links the available capacity of the energy storage system with the battery discharge rate and the discharge ampere-hour flux. Furthermore, a topology reconstruction strategy is proposed to ensure the maximum available capacity of the energy storage system, which is solved using the longitudinal and transverse cross algorithm. By comparing the overall capacity difference between reconfigurable energy storage systems and traditional energy storage systems under low-power demand through simulation, the effectiveness of the algorithm was verified, and the proposed strategy was demonstrated for optimizing the capacity of the energy storage system.

When the low voltage level islanded microgrid is in parallel operation, due to the difference in line impedance and the impact of load change, the traditional droop control strategy has the problem that the reactive power can’t be accurately allocated, resulting in the existence of reactive circulating current phenomenon in the system. To address this problem, this paper proposes a control strategy based on adaptive virtual impedance. The virtual impedance is adjusted according to the reactive power output from the two inverters through the integration link, and the voltage generated by the virtual impedance is superimposed with the output voltage of the droop control to adjust the output reactive power, so as to achieve the purpose of equalizing the reactive power and suppressing the system circulating current. The simulation results show the effectiveness of the proposed control strategy.

Addressing the limitation of point prediction in conveying adequate uncertainty information, this paper introduces a precise method for short-term photovoltaic power interval prediction. Initially, Pearson and Spearman double correlation coefficients are employed to assess the correlation between various meteorological factors and photovoltaic power generation. Subsequently, the Fuzzy C-means (FCM) clustering technique is utilized to categorize historical datasets into three distinct categories. Following this, we propose a QR-BiGRU hybrid model that integrates bidirectional gated recurrent units (BiGRU) with quantile regression (QR) model. Finally, we compare our model against QR-LSTM, QR-BiLSTM, and QR-GRU models using multiple evaluation metrics to assess their predictive performance. The experimental results indicate that the interval prediction approach presented in this study demonstrates high accuracy and offers valuable insights for scheduling within power departments.

Based on the typical structural characteristics of hollow cup flywheel motors, this article analyzes the main sources of remanence, and concludes that the remanence of the motor is mainly the vector sum which caused by permanent magnet magnetic circuit and the armature windings that varying through the current. An equivalent mathematical model and simulation model for remanence generated by the armature windings were given, and the influence of different driving mode on remanence of the motor was studied. The conclusion was drawn that the remanence of hollow cup flywheel motors is smaller in the full bridge drive modes. Experiment results confirm that the validity of theoretical analysis and finite element simulation. The result can provide improvement ideas for the better application of flywheel products on magnetic clean satellite platforms.

As a key component of energy structure transformation, integrated energy systems effectively realise the synergistic operation of multiple heterogeneous energy sources. However, the existing studies on the optimal operation of integrated energy systems have not taken into account the system structure improvement and model refinement, which makes it difficult to fully grasp the complex interaction mechanisms and optimisation potentials within the system. In order to address this limitation, this paper proposes an optimal scheduling method for the integrated electricity-gas energy system that takes into account the dynamic characteristics of the gas network. Firstly, a two-stage P2G model and a gas network dynamic model are established by considering the two-stage P2G operation characteristics and the gas dynamic transmission characteristics. Then, the optimal scheduling model of the integrated electric-gas energy system including the two-stage P2G, gas turbine and other key equipments is constructed. Finally, the effectiveness and superiority of the proposed method in improving system energy efficiency and reducing costs are verified through simulation.

Time-Dependent Dielectric Breakdown (TDDB) testing is a crucial method for investigating the reliability and predicting the lifetime of power device gate oxides. In traditional lifetime prediction, the Weibull distribution of failure time often exhibits distortion in the Weibull slope, which impacts the accuracy of lifetime prediction. Firstly, a TDDB experimental platform was developed to enable long-term continuous online measurement of gate leakage current, resulting in more precise failure time data. Secondly, an analysis of the Weibull distribution results for failure time and failure charge was conducted based on percolation model theory and E-model theory for lifetime prediction, revealing that internal accumulated charge in the gate oxide can better reflect device failure. Finally, through theoretical analysis, hypothesis testing, and goodness-of- fit testing for Weibull distribution, we compared and analyzed the representative effects of offline gate leakage current, threshold voltage, and composite flat band voltage on accumulated charge. The findings indicate that composite flat band voltage can more accurately assess the progression of time-dependent dielectric breakdown failure.

The imbalance of midpoint potential directly affects the output voltage waveform quality of the diode-clamped three-level inverter (NPC) and the service life of the device. Aiming at the problem that the traditional virtual space vector method cannot actively control the midpoint potential offset and the switching frequency is higher, an improved virtual space vector method is proposed to reduce the switching frequency under the low modulation regime, When the modulation regime is low, two combinations of small vectors of equal amplitude and opposite sign to the total effect on the midpoint potential are obtained by using only positive small vectors for one small vector and only negative small vectors for the other small vector. Then dynamically select the combination of small vectors to be used by judging the size of the midpoint potential in real time, so as to realize real-time control of the midpoint potential offset. The method can ensure the balance of the midpoint potential as well as quickly control the midpoint potential offset, and also greatly reduce the switching frequency due to the non-use of redundant small vectors. Finally, a simulation model is built in Matlab/Simulink, and a simulation comparison between the traditional virtual space vector method and the improved virtual space vector method proposed in this paper is carried out to validate the method in the low-tuning regime.

Because of its excellent insulating properties and environmental performance, the perfluoroisobutyronitrile (C4F7N) gas mixture is the most promising alternative to greenhouse insulating gas sulfur hexafluoride (SF6). However, after multiple arc extinguishing processes, various decomposition residual products will be produced, and the impact on the safety of maintenance personnel is still unknown. Therefore, this paper systematically evaluated the biological safety of C4F7N/Air decomposition residual products. The results demonstrated that the decomposed C4F7N/Air gas exhibits substantial acute toxicity when inhaled with an LC50 value of 31.21 parts per million for male lab mice (four hours), significantly lower than that of pure C4F7N gas. As a result, personnel involved in the operation and maintenance of electrical equipment must strictly adhere to safety precautions.

Tree Obstacle Clearing in Power Channels is one of the most important aspects of inspection. Traditional inspections rely heavily on field surveys conducted by personnel, which are highly dependent on operational experience and are inefficient and unsafe, making them unsuitable for the needs of smart grid construction. This paper establishes a real-time tree obstacle analysis method using UAV LiDAR. To meet the real-time requirements of point cloud processing, the UAV LiDAR system is paired with a self-developed onboard computer that interprets point cloud data in real-time during flight. The method involves merging and segmenting point cloud frames, determining target areas using tower records, constructing voxel features for point cloud classification, and utilizing three-dimensional spatial distance analysis for hazard analysis. On-site comparative experiments show that this method can achieve real-time detection of tree obstacles in power channels with high accuracy, significantly improving the quality and efficiency of tree obstacle hazard detection in existing transmission lines and strongly promoting the intelligence of power grid inspections.

To fully explore the correlation and temporal characteristics between online monitoring data of dissolved gases in oil-immersed transformers, and to improve the accuracy of early defect warnings and defect type identification, a method based on Jensen-Shannon divergence and dynamical network marker is proposed for early transformer defect warning and identification. First, the monitored quantities of dissolved gases in transformer oil are mapped as nodes of a complex network reflecting transformer state evolution, allowing the analysis of transformer deterioration based on the time-series monitoring data. Then, prediction models for the components of dissolved gases are established using historical health condition data from the transformer’s oil chromatography online monitoring system. Jensen-Shannon divergence is introduced to construct an inconsistency indicator, quantifying the dynamic difference between actual monitored values and predicted values under healthy conditions. This helps identify critical dynamical network marker during defect-prone states. Case studies show that this method can not only provide accurate early warnings for transformer defects but also effectively identify defect types.

The transfer function of the duty cycle to the output voltage of the Boost controller in the inductor current continuous conduction mode ( CCM) mode is analyzed. Due to the existence of the second-order oscillation link and the zero point of the right half plane, if the single-pole compensation network is used under the single-voltage control, the crossing frequency of the corrected system is less than the natural oscillation frequency, and it is difficult to have good dynamic performance. In order to improve the control bandwidth of the system, a controller is composed of a double pole double zero point compensation network and a phase lead compensation network to compensate the Boost single voltage. In this paper, the parameters of the controller are calculated in detail, and the correctness of the controller design is verified by simulation. Compared with the single pole controller, it shows that the controller has good rapidity and stability.

To study the influence of extrusion temperature on the mesoscopic morphology and comprehensive properties of high-voltage cable insulation masterbatch, and analyze its mechanism, insulating materials with different mesoscopic micro-morphologies were prepared by controlling the extrusion temperature of the insulating material. Then, combined with the microscopic characterization of the system, comprehensive electrical and mechanical performance testing, and simulation methods, the reasons for the performance differences of insulating materials are revealed and the mechanism is verified and analyzed. The results showed that at an extrusion temperature of 120 ℃, the insulation material could be fully plasticized without excessive melting, and the crystallinity and crystal size of the insulation material reached the optimal values of 42.28% and 15 μm, presenting a dense and uniform crystal configuration. Based on the mutual verification of simulation and experimental results, it can be concluded that a perfect crystal configuration, significantly increased crystal size, and crystallinity can synergistically enhance the comprehensive electrical and mechanical properties of insulation materials, resulting in optimal values of 7.85 × 1017 Ω·cm, 390 kV/mm, 17.1 MPa and 675% for volume resistivity, breakdown performance, tensile strength, and elongation at break, respectively.

Energy storage converters are widely used in power systems, new energy vehicles, wind power generation and other fields, and are of great significance in grid peak shaving, valley filling, smoothing new energy fluctuations and other aspects. The sampling part plays an important role as a bridge between the primary and secondary side control of the energy storage converter device. The accuracy of the sampling part directly affects the accuracy of the control algorithm. The sampling part of this paper includes a sampling circuit, a conditioning circuit and a calibration design. The sampling circuit is composed of a Hall voltage and current sensor. The AC voltage and current signals output by the sensor cannot be directly input to the A/D converter of the DSP. The output values need to be converted into 0 to 3V signals through the signal conditioning circuit and then input to the A/D converter. The calibration design is to calibrate and normalise the digital quantity output by the A/D converter, and then apply it to the control algorithm to improve the speed of the control algorithm. Finally, the accuracy of the sampling is verified by comparing the oscilloscope waveform with the upper computer sampling waveform through precharging experiments and energy storage discharge experiments of the energy storage device.

In the de-icing technology of wind turbine blades, microwave de-icing, an environmentally friendly, efficient, and energy-saving method, has significant advantages over traditional de-icing techniques. Microwave de-icing utilizes microwave heating absorbing coatings, allowing the surface coatings of the blades to absorb microwave energy and convert it into heat energy. Therefore, studying the microwave absorption properties of coatings under microwave irradiation is crucial. In this paper, silicon carbide, iron (III) oxide, and graphite/polyurethane composite coatings with 12 different ratios and thicknesses were designed. Microwave heating experiments were conducted on the composite coatings using a 2.45 GHz frequency microwave to explore the effects of the coating ratio, coating thickness, microwave output power, and microwave irradiation distance on the microwave absorption properties of the composite coatings. The experimental results show that under the same conditions, the graphite/polyurethane composite absorbing coating heats the fastest, followed by the iron (III) oxide/polyurethane composite coating, and the silicon carbide/polyurethane composite coating heats the slowest. The microwave absorption properties of the composite coatings are positively correlated with the microwave output power and coating ratio, and negatively correlated with the microwave irradiation distance. However, they are also affected by the microwave heating conditions, where under the same microwave energy, the heating effect of the coating under low power for a long time is superior to that under high power for a short time.

The open-core voltage transformer has the advantages of flat U-I curve and good anti-ferroresonance performance, but there are still few studies on the electromagnetic characteristics of it. In order to promote the knowledge and understanding of the electromagnetic characteristics of the open-core voltage transformer, the difference between the open-core voltage transformer and the closed-core voltage transformer on the U-I curve and the reason why the open-core voltage transformer has excellent anti-ferroresonance performance are analyzed from the theoretical point of view. Then, the core parameters including the shape and material of the core and the number of winding turns are selected as the influencing factors, and their influence on the error of the open-core voltage transformer is studied by simulation analysis. Finally, based on the simulation results, some suggestions are put forward for the design of the open magnetic circuit voltage transformer.

This paper studies a new energy vehicle-pile matching method based on privacy protection technology, aiming to solve the user privacy leakage problem encountered in the charging process of new energy vehicles. In order to protect user data privacy, a privacy protection method based on OT-Extension bidirectional authentication protocol, private set intersection (PSI) and private information retrieval (PIR) cryptography techniques is proposed to realize effective interaction and query of pile data. Based on XGBoost model, a car pile matching model is constructed using federated optimization to optimize the matching of charging piles. By training and predicting the data of user's charging demand and charging pile state, the car pile matching model can match charging pile efficiently. Finally, security analysis and performance evaluation are carried out on the results of the proposed pile matching model, and comparison with logistic regression model proves the reliability, feasibility and effectiveness of the privacy protection technology in this paper in the pile matching method.

With the long-term operation of the aircraft and the gradual increase of the age of the aircraft, multiple factors such as wiring harness expansion and contraction, vibration and so on may lead to the failure of the aircraft wiring harness. This paper starts from the actual failure phenomenon of the aircraft and analyzes the failure mechanism. The fault mechanism was simulated by the thermal simulation of the wire harness, and the factors affecting the thermal temperature rise of the wire harness were analyzed. According to the results of the simulation, laboratory experiments were carried out to reproduce the fault process and fault phenomena, and the effectiveness of the simulation method was verified. A reliability prediction method based on the influence of core damage degree and wire harness temperature rise is proposed. It provides guidance and suggestions for the impact hazard assessment and reasonable selection of maintenance methods when the aircraft conductor is damaged.

Throughout the entire lifecycle of electric vehicles, carbon emissions are generated from their manufacturing, usage, and disposal processes. To effectively harness the energy-saving and emission-reducing benefits of electric vehicles, this article focuses on the usage phase and proposes a charging guidance method that takes into account green electricity consumption. By integrating green electricity subsidies with time-of-use electricity pricing, users are guided to charge during the green electricity output period, maximizing the consumption of green electricity. Initially, we formulate green electricity subsidy prices for each time period based on photovoltaic output characteristics, encouraging users to switch from non-green to green electricity periods for charging through these subsidies. Subsequently, during the green electricity period, considering the total photovoltaic output constraints at different times, we provide charging guidance to users who need to charge. By optimizing the price at which green electricity operators sell green electricity to users through time-of-use pricing, we ensure the revenue of green electricity operators. The calculation results demonstrate that the proposed charging guidance method can effectively enhance the green electricity consumption capacity of electric vehicles and improve their carbon reduction effect during usage.

In order to investigate the application of Interior Permanent Magnet (IPM) machines in the aerospace high-speed starter generation system, a 250 kW, 25000 r/min high-speed permanent magnet starter generator for aircraft is designed. An analytical stress model of the interior permanent magnet rotor structure is established to analyze the structural strength and optimize the carbon fiber sleeve. The accuracy of the stress model is verified with help of the finite element analysis (FEA). The FEA is used to analyze the electromagnetic characteristics of the machine, and the efficiency of the starter generator fed by converter is analyzed by the field-circuit co-simulation. The rationality of the design scheme is verified, which would be helpful on the application of the interior permanent magnet motor in the aviation system.

Aiming at the problems of large heat dissipation and high cooling difficulty in the electric drive system of new energy vehicles, this paper designed and developed an oil-water composite motor cooling system based on the Computational Fluid Dynamics (CFD) method. The three-phase quadrupole asynchronous motor was taken as the research object, we analyzed the cooling medium and its flow rate, water jacket structure design and water jacket section area by simulation. The results showed that water is the best cooling medium under the same flow rate and channel structure. When the flow rate of cooling oil is 1.5 m/s and the flow rate of cooling water is 1 m/s, the parameters of the motor are the best. Considering the heat dissipation efficiency and water pressure, the H-shaped channel is more suitable for the actual heat dissipation process of the motor. Similar parameters on the top and bottom of the trapezoidal section of the water jacket can better balance the pressure drop and heat dissipation effect.

This paper investigates the use of Electrical Impedance Spectroscopy (EIS) to measure the electrical impedance characteristics of bones. By employing the least squares method to fit the Cole-Cole plot, the study aims to extract characteristic parameters and explore their relationship with bone density. Fresh sheep lumbar vertebrae were used as samples, and demineralization treatment was applied to simulate osteoporosis. The impedance spectra were measured and analyzed under various treatment conditions. The results demonstrate a significant correlation between the characteristic frequency (fc) and bone density, with most data points falling within the 95% confidence interval. This finding validates the reliability and effectiveness of this method. The study indicates that EIS, combined with the Cole-Cole model, has potential applications in osteoporosis detection. It offers a non-invasive, radiation-free, and cost-effective approach for bone density assessment, providing new possibilities for the early diagnosis and monitoring of osteoporosis. This method could significantly enhance the current capabilities for osteoporosis management and treatment.

In recent years, China has made significant breakthroughs in photovoltaic and hydroelectric power generation, effectively alleviating the problem of energy shortage. However, the high proportion of new energy access has led to an increase in power electronic devices, and has also exacerbated the problem of sub synchronous oscillations below the synchronous frequency caused by their interaction with the power grid. In order to reduce the impact of photovoltaic grid connection on the stability of the power system and avoid significant economic losses caused by sub synchronous oscillations, it is necessary to conduct research and analysis on photovoltaic grid connection systems. This article focuses on the problem of sub synchronous oscillation in photovoltaic grid connected systems. Firstly, a mathematical model of the photovoltaic power generation system is established, which includes photovoltaic arrays, inverters and their control systems, phase-locked loops, L-shaped filters, and transmission lines. Secondly, based on the mathematical model of the photovoltaic power generation system, modular modeling methods are used to derive and establish small signal models for each subsystem, and obtain the state space model of the photovoltaic power generation system. Finally, using the eigenvalue analysis method, the impact of different inverter and phase-locked loop control parameters, as well as the root locus of photovoltaic output changes, on system stability is studied and analyzed. The experimental results indicate that changes in control parameters and photovoltaic output will have varying degrees of impact on the sub synchronous oscillation generated by the photovoltaic power generation system.

Transient voltage stability is of significant importance for the stable operation of power systems. To swiftly and accurately assess the transient voltage stability condition following a fault in the power system, an evaluation method combining attention mechanism (AM) and bidirectional long short-term memory network (BiLSTM) is proposed. Firstly, the transient input data representing the operating state of the power system are constructed by the electrical quantity of each node in the three stages of pre-fault, fault and post-fault. Then, the BiLSTM deep neural network algorithm is constructed to fully capture the time series features of transient data, and the AM is incorporated for assigning feature weights, thereby increasing focus on the most significant ones. In addition, to improve the model tendency problem caused by the inherent class imbalance of transient samples, the weighted cross entropy loss function (Wce) is used to supervise model training in the training process. Ultimately, the IEEE 39-bus system is considered as a case for validating the precision and efficiency of the proposed approach.

Fiber optic ultrasonic sensors based on Fabry-Perot (F-P) interference can have their probes embedded within transformers, offering advantages in sensitivity and anti-interference capability. However, the internal environment of transformers is complex, and factors such as temperature, pressure, and electric fields may affect the performance of fiber optic F-P sensing probes, altering their operational characteristics. Therefore, this paper investigates the influence characteristics of the transformer internal environment on fiber optic F-P ultrasonic sensors. The effects of temperature and liquid pressure on the fiber optic F-P probe were studied through experiments, and the distribution of the externally applied electric field within the fiber optic F-P probe was analyzed through simulations. It was found that the impact of temperature on the fiber optic F-P probe is significant and should be a primary focus, while the effect of liquid pressure on the cavity length of the fiber optic F-P probe is minimal. The electric field distortion increases within the F-P interference cavity, suggesting that the fiber optic F-P probe should be placed at the transformer edge in low field strength areas, and propose an edge computing-based suppression strategy for temperature interference. This study aids in the design and application of embedded fiber optic F-P probes.

Electromagnetic voltage transformers (PTs) are prone to ferromagnetic resonance due to external disturbances, causing the fuse on the high-voltage side of the PT to burn out and endangering the stable operation of the power system "Q1" Text="This is to inform you that corresponding author and email id have been identified as per the information available in the Copyright form." . In the article, the instantaneous symmetrical component method is first used to calculate the resonant overcurrent caused by PT saturation, and the influencing factors of PT transient overcurrent are obtained. Using ATP-EMTP electromagnetic transient simulation software to build a simulation model of 10 kV distribution network, considering the nonlinear characteristics of PT excitation winding, an ideal transformer and a 98 type nonlinear inductor parallel resistor are used to establish the PT model; The PT open zero sequence voltage signal obtained from simulation is decomposed into a series of product function (PF) components through local mean decomposition (LMD). The amplitude and frequency information of each order PF component is extracted through Teager energy operator (TEO), and then integrated along the time axis to obtain the LMD-TEO marginal energy spectrum. Frequency division resonance and high-frequency resonance are identified based on the frequency value corresponding to the maximum peak of the LMD-TEO energy spectrum; Using Hilbert phase difference to calculate the phase difference of zero sequence current and zero sequence voltage of each outgoing line L1, L2, L3 after PT resonance and single-phase grounding fault, in order to identify power frequency resonance.

The lead seal of cable terminals plays a critical role in the sealing and waterproofing of high-voltage cables, and its reliability is directly related to the safe operation of the cable system. During the manufacturing and installation processes, defects such as cold soldering, loosening, and cracking may occur in cable lead seals, making traditional detection methods insufficient for identifying these internal defects effectively, thus increasing the risk of cable failures. This study systematically investigates the detection methods and effectiveness of ultrasonic technology for lead seal defects at cable terminals. The experiment employs the HS PA20 ultrasonic testing equipment developed by Zhongke and utilizes the design of a flexible probe and a coupling medium water bag to enhance the precision and reliability of ultrasonic detection. Experimental results show that ultrasonic detection can effectively identify inter-layer and internal defects of lead seals, providing scientific evidence and technical support for the on-site non-destructive detection of lead seal defects at cable terminals.

Joint motors are the core power source of highly dynamic humanoid robots, requiring designs with high torque density and low torque ripple. Due to the unique permanent magnet arrangement, Halbach array with a magnetic flux focusing effect is a promising candidate for use in joint motors of humanoid robots. Based on various Halbach array configurations (two-segment, three-segment, and four-segment) and magnetization angles, this paper investigates the difference of electromagnetic performance between traditional radial magnetization and Halbach array configurations in outer rotor permanent magnet synchronous motors (PMSMs), including air gap flux density, back EMF, cogging torque, electromagnetic torque, and motor losses. The results indicate that each Halbach array configuration has an optimal magnetization angle to achieve the maximum torque. Moreover, the three-segment Halbach array configuration shows an 11.4% improvement in electromagnetic torque and a 21.44% reduction in torque ripple compared to the traditional radial magnetization, significantly enhancing the motor's electromagnetic performance.

This study presents the application of Electrical Capacitance Tomography (ECT) for real-time monitoring and imaging of combustion flames in industrial burners. Given the importance of understanding flame characteristics—such as stability, thermal efficiency, and pollutant emissions—this research addresses the limitations of existing optical, thermal, acoustic, and electrical detection methods in harsh industrial environments. ECT, a non-invasive and cost-effective technique, was employed to visualize the distribution of dielectric constants in the flame, which correlates with combustion intensity. A novel design of nine-electrode sensors, optimized for placement at the burner nozzle, was proposed and simulated. Sensitivity field distribution and sensor geometry were fine-tuned for accurate detection. The study utilized Landweber and Tikhonov regularization algorithms for image reconstruction, with the latter proving superior in clarity and correlation. The results demonstrate the feasibility of using ECT for precise flame monitoring, offering potential improvements in burner design and operation.

T-type three-level inverter has been widely used in medium-voltage and high-power situations, but its own topological characteristics make it have the problem of midpoint potential imbalance. Based on the space vector pulse width modulation of T-type three-level inverter, this paper analyzes the influence of large, medium, small and zero vectors on the midpoint potential, and presents a control method of constructing virtual vectors and balancing the midpoint potential by using redundant small vectors and large vectors or zero vectors. Finally, the simulation results in MATLAB/Simulink demonstrate the effectiveness of the proposed method.

Aiming at the problem of insufficient operation capability of virtual synchronous generator (VSG) when an asymmetric drop fault occurs in the power grid, and the output current distortion and power fluctuation of grid-connected inverter, propose a VSG power and current coordinated control strategy based on fast delay signal cancellation (FDSC) filtering theory, without the need for phase-locked loops and asymmetric voltage positive and negative sequence calculation. First, the intrinsic relationship between the reference current and the two control objectives of VSG power constant and current balance is analyzed. Secondly, the reference current of the instantaneous power is calculated through the VSG virtual power. Then FDSC is used to extract the harmonic in the reference current and introduce adjustment. The coefficient controls its content to achieve coordinated control of constant output power and output current balance. Finally, the effectiveness of the proposed control strategy is verified through simulation.

The drive motor is the core component of electric vehicles, its comprehensive performance requirements are extremely high, AC induction motor due to the cast aluminum rotor is often used, making the rotor broken bars and thin bars defective faults are very common, based on the driving safety, comfort, and other considerations, it is very necessary to explore these faults on the performance of the motor impact law. In summary, the article mainly analyzes the magnetic field and NVH changes of the rotor defective faults of a certain AC induction motor for electric vehicle drive, and the specific work is as follows: firstly, according to the cast aluminum rotor structure adopted in a certain drive motor, the finite element model of different defective faults of the rotor is established by using the equivalent resistance method; secondly, the influence law of different degrees of defects of the rotor guide strip on the electromagnetic field of the motor is compared, and the preliminary determination of the faults make the It is initially determined that the defects cause obvious distortion of the local field quantity of the motor, which in turn causes a sharp increase in the rotor guide current, electric density and torque fluctuation. Finally, theoretical analysis and simulation calculations are carried out for the impact of NVH, and the results show that the failure of the guide strip will additionally generate low-frequency electromagnetic force smaller than the fundamental frequency of the electromagnetic force, and the number of broken strips increases dramatically, which will bring about a serious NVH problem.

In the majority of 500 kV substations, the voltage on the 500 kV busbars is regulated within a specific permissible range through the switching of 35 kV low-voltage reactors or capacitor banks, ensuring the safety and economic efficiency of system operation. Within the context of the new-type power system, reactive power fluctuations have intensified, exposing circuit breakers to extreme operating conditions such as high-frequency inrush currents, overvoltages, and frequent operations during switching. After a certain number of operations, issues like poor contact between components and severe ablation and wear of contacts can arise, leading to an abnormal increase in loop resistance and compromising the circuit breaker’s safety throughout its service life. This paper dissects and analyzes typical circuit breakers exhibiting excessive loop resistance during actual operation, with a particular focus on the service conditions of key materials such as electrical contacts and their impact on loop resistance. Subsequently, targeted optimization measures are proposed to ensure the stable performance of circuit breakers and the safe operation of the power grid.

Permanent magnet brushless DC motors (BLDC) have the advantages of high power density, high operating efficiency, and are increasingly widely used in oil extraction, aerospace, and military industries. This paper designs a high-temperature BLDC motor, determines that its optimal slot and pole number combination is 9-slot/8-pole, the motor parameters are calculated using the rated parameter analysis method. Adopting the principle of fixed copper consumption, the stator size of the motor is optimized using genetic algorithm to achieve the maximum average torque. The finite element method (FEM) is used to optimize the no-load and load performance. The temperature field model of the motor is established, and the “magnetic-thermal” iterative coupling calculation study of the motor is carried out, the temperature rise characteristics of the motor in a 200 ℃ high-temperature oil well environment are analyzed, and the motor torque is compensated.

This study aims to enhance the effectiveness of unmanned aerial vehicle (UAV) inspection systems for power lines under extreme weather conditions. It proposes a novel approach using the narrow beam and low sidelobe properties of W-band millimeter wave radar to develop an imaging algorithm specifically tailored for power line detection. By exploiting the Bragg scattering phenomenon exhibited by power lines, the algorithm not only identifies azimuth and range information but also generates high-resolution radar images of 500 kV power lines. This achieves a range resolution of 0.15 m, surpassing the 0.45-m spacing between the quad-bundle conductors in 500 kV power lines. The findings underscore the feasibility of employing millimeter wave radar in UAV-based power line inspection, thereby significantly advancing the safety and efficacy of intelligent power drone inspections.

Modular multilevel DC transformers can interconnect DC lines of different voltage levels and types, serving as a hub for high-voltage DC collection and transmission. Currently, research on modular DC transformers is still in the stage of circuit topology design and functional verification, and a unified, general controller design method has not been established in terms of control. Therefore, this paper takes the average value model of a modular DC transformer as the research object. It first analyzes the characteristics of the topology structure and the principle of voltage transformation. Then, it derives the common /differential constraint relationships of AC components and the dynamic characteristic equations of internal and external electrical quantities. Finally, aiming to achieve energy balance among the submodules of each bridge arm and reduce the amplitude of internal circulating current, a hierarchical control strategy is proposed to decouple and operate the controllers independently, achieving the goals of power transmission and stable voltage transformation. Lastly, the effectiveness of the proposed control method is verified in MATLAB/SIMULINK.

In this paper, a anomaly data cleaning method based sliding standard deviation for distributed photovoltaic power plants is proposed. Due to lack of irradiance measurement information, the DC voltage and output power were selected for data cleaning. The DC voltages were categorized into three groups, the before starting voltage group, the low irradiance operating group and the normal operating group. The method is used for abnormal data identification through grouping of DC voltages, calculation of sliding standard deviation and threshold setting. The data of a real distributed PV plants are take as a example and the results illustrate the effectiveness of the method by cleaning the abnormal data.