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Review of Research on Low Voltage DC Arc Detection and Interruption Technology LI Xingwen, ZHANG Zhaozi, YANG Haowen, MENG Yu, WANG Qian, CHEN Silei LOW VOLTAGE APPARATUS    2024, 0 (8): 1-10.   DOI: 10.16628/j.cnki.2095-8188.2024.08.001 Abstract （189）   HTML （10）    PDF （1230KB）（128）       Knowledge map    Save DC arc accurate detection and fast breaking technology is the key to ensure the safe,stable and reliable operation in low voltage DC power distribution systems.Firstly,DC arc fault detection technologies in the new scenario of transport are summarized.The multiple kinds of time-frequency domain feature construction algorithms and intelligent models based on the machine learning are analyzed,and a variety of DC arc fault localization techniques using electromagnetic and current signals are introduced.Secondly,the fast interruption technology for low voltage DC systems is reviewed,and the traditional mechanical circuit breaker interruption methods are summarized.The research progress of hybrid circuit breakers and solid-state circuit breakers based on the development of power electronic devices is introduced.Finally,the development direction of low voltage electrical design field is finally proposed,which helps provide references for relevant researchers. Table and Figures | Reference | Related Articles | Metrics

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Research and Application of Intelligent Anti-Misoperation Technolgy for Substation Switching Operation Based on Artificial Intelligence HU Xinyu, YU Haipeng, HE Zhi, ZHAO Miaomin, XING Songyao, ZHANG Jinwei LOW VOLTAGE APPARATUS    2024, 0 (6): 70-79.   DOI: 10.16628/j.cnki.2095-8188.2024.06.011 Abstract （185）   HTML （6）    PDF （13069KB）（51）       Knowledge map    Save In response to the current lack of effective error prevention verification methods and low level of intelligence in operation tickets, a knowledge graph based intelligent error prevention technology for substation switching is proposed by combining deep reinforcement learning algorithms. Firstly, the data such as power grid equipment topology and scheduling error prevention regulations is utilized to constructe a physical entity graph and an error prevention semantic graph of the equipment, and a scheduling knowledge graph is automatically fused to form. Then, based on intelligent error prevention algorithms, a graph of error prevention regulations is constructed to automatically generate the optimal switching operation sequence that complies with the error prevention regulations, and the intelligent error prevention verification is achieved. Finally, the practicality of knowledge graph intelligent error prevention, the performance of deep reinforcement learning, and the efficiency of intelligent error prevention are analyzed through examples. The results show that the proposed method has certain advantages in improving the efficiency and accuracy of intelligent error prevention for switching. Table and Figures | Reference | Related Articles | Metrics

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Simulation of Tripping Process of Miniature Circuit Breaker Based on Maxwell 3D/ADAMS WANG Bingqing, ZHANG Senlin LOW VOLTAGE APPARATUS    2024, 0 (7): 74-78.   DOI: 10.16628/j.cnki.2095-8188.2024.05.012 Abstract （180）   HTML （6）    PDF （1595KB）（111）       Knowledge map    Save To improve the accuracy of traditional dynamic simulation,the virtual prototyping technology is used to simulate the instantaneous trip process of circuit breaker based on Maxwell 3D and ADAMS.Firstly,the electromagnetic transient dynamic simulation finite element model of the tripper is established by using Maxwell 3D,and the simulation results of the transient electromagnet motion characteristics are obtained by calculation.Then the calculation results are imported into ADAMS to simulate the instantaneous tripping process of circuit breaker.Finally,the instantaneous release test of the actual prototype is taken by high-speed photography.The correctness of the simulation is verified.The co-simulation can improve the accuracy of dynamic simulation. Table and Figures | Reference | Related Articles | Metrics

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Research Progress on Active Protection Against Thermal Runaway of High Power Fast Charging Lithium-ion Batteries LIU Jianchao, GUO Weiwen, LU Deng, YANG Liming, JIANG Caisheng LOW VOLTAGE APPARATUS    2024, 0 (11): 10-19.   DOI: 10.16628/j.cnki.2095-8188.2024.11.002 Abstract （177）   HTML （7）    PDF （3204KB）（115）       Knowledge map    Save Short cruising range and long charging time of electric vehicles seriously restrict their rapid development.To solve these problems,high-power fast charging of electric vehicles has revealed as an attractive strategy.Solving the thermal safety caused by high-power fast charging of lithium-ion batteries is an important prerequisite for supporting the development of fast charging.By summarizing home and abroad literature firstly, the mechanism of high power fast charging and thermal runaway of lithium-ion batteries is clarified.Secondly,starting from the optimization methods,liking fast charging strategy,battery design and manufacturing process,fast charging thermal management,etc.,the research progress of high power fast charging thermal runaway active prevention and control of lithium-ion batteries is stated,which provides the development ideas for thermal runaway prevention and control technology to accelerate the development of high power charging of lithium-ion powered batteries. Table and Figures | Reference | Related Articles | Metrics

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Technical Research on Interleaved Parallel Boost PFC Circuit RONG Jun, WAN Junhua, NIE Guiyang LOW VOLTAGE APPARATUS    2024, 0 (12): 47-50.   DOI: 10.16628/j.cnki.2095-8188.2024.12.008 Abstract （164）   HTML （5）    PDF （1938KB）（50）       Knowledge map    Save In response to the problem of excessive voltage stress in the switching devices of conventional Boost converters,the interleaved parallel Boost converters were studied.Firstly,the advantages of interleaved parallel Boost power factor correction(PFC) circuits in reducing input current ripple,inductor core size,and output capacitor current were derived.Then,the key parameters of the main circuit of the converter,and a double closed-loop control system based on average current control were designed.Finally,it was verified by the simulation experiments.The results show that the interleaved parallel Boost converters can not only achieve the power factor correction well in high-power situations,but also effectively reduce the current stress of power devices,the input current ripple and the volume of inductor magnetic components,and improve power levels. Table and Figures | Reference | Related Articles | Metrics

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A Comprehensive Review of Electromagnetic Relay Remaining Useful Life Prediction Methods MA Dongkun, WANG Zhaobin, HE Tianyang LOW VOLTAGE APPARATUS    2024, 0 (7): 1-8.   DOI: 10.16628/j.cnki.2095-8188.2024.07.001 Abstract （159）   HTML （6）    PDF （1666KB）（113）       Knowledge map    Save This comprehensive review focuses on the technological advancements in predicting the remaining useful life (RUL) of electromagnetic relays,offering an insightful overview of the current research landscape.The existing methodologies for predicting the RUL of electromagnetic relays are systematically organized and contrasted.The application status and efficacy of various prediction techniques is delved into,including grey system models,statistical analysis,and neural networks.By examining recent scholarly articles,the review highlights the strengths and limitations of these diverse methods,emphasizing their role in enhancing the reliability of power systems.While each approach contributes to some extent in predicting the RUL of electromagnetic relays,significant variations persist in terms of accuracy,applicability,and user-friendliness.The future research direction is pointed that the hybrid models integrated multiple prediction technologies and the practical prediction systems incorporated real-time monitoring data are developed to augment the precision and applicability of RUL predictions. Table and Figures | Reference | Related Articles | Metrics

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Study on Arc Reignition Influencing Factors of HVDC Relay Under Permanent Magnet Field LIN Zhen, ZHANG Peng, LIU Xiangjun LOW VOLTAGE APPARATUS    2024, 0 (8): 34-44.   DOI: 10.16628/j.cnki.2095-8188.2024.08.005 Abstract （159）   HTML （3）    PDF （2285KB）（72）       Knowledge map    Save Arc reignition is an important reason for prolonging the disconnection time of highvoltage DC relays.In order to study the reignition characteristics inside the arc extinguishing chamber,the permanent magnet magnetic field was simulated by Comsol Multiphysics and the result was used as the basic condition for arc simulation.The dynamic characteristics of the arc and the reasons for arc reignition under the influence of magnetic field strength,breaking speed,contact shape,and atmospheric pressure were simulated and analyzed.A four factor three-level orthogonal experiment was designed,and the degree of influence of each factor on arc reignition was studied through simulation.The results indicate that the heat dissipation conditions in the arc gap and the electric field strength exerted by the arc voltage on the arc gap are important reasons for arc reignition.The worse the heat dissipation conditions or the higher the electric field strength exerted by the reverse arc voltage,the easier it is for arc reignition to occur.The degree of influence of four factors on arc reignition is in the order of breaking speed,gas pressure,contact shape,and magnetic field strength. Table and Figures | Reference | Related Articles | Metrics

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Modeling and Research on Grid-Forming Energy Storage Based on Vanadium Redox Flow Battery DOU Yan, WANG Chuanyi, CHEN Zihui, WANG Chen, LI Xin LOW VOLTAGE APPARATUS    2024, 0 (11): 29-37.   DOI: 10.16628/j.cnki.2095-8188.2024.11.004 Abstract （156）   HTML （4）    PDF （2866KB）（73）       Knowledge map    Save To address the intermittent and unstable issues of high-proportion new energy grid connection and enhance its utilization efficiency,the grid-forming energy storage system based on vanadium redox flow batteries (VRFB) is focused on.The research employs a multi-physics field-coupled VRFB hybrid model to simulate its dynamic operation characteristics comprehensively.Based on this,a flexible charge and discharge control strategy based on the outer loop of the DC bus voltage is designed,and the virtual synchronous generator (VSG) control technology is integrated to achieve precise control of VRFB’s charge and discharge.The effectiveness of the strategy is verified through modeling and simulation in MATLAB/Simulink.The results indicate that this strategy can stabilize the output terminal voltage during long-term discharge and performs outstandingly in photovoltaic/VRFB grid-connected operation,frequency and voltage regulation,and maintaining the stability of the DC bus voltage,which can validate the application potential of VRFB in the field of grid-forming energy storage. Table and Figures | Reference | Related Articles | Metrics

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Research on Multiload Wireless Power Transfer Characteristics Based on PT Symmetry WANG Menghuan, LIU Weiqing LOW VOLTAGE APPARATUS    2024, 0 (12): 1-9.   DOI: 10.16628/j.cnki.2095-8188.2024.12.001 Abstract （145）   HTML （9）    PDF （2334KB）（84）       Knowledge map    Save In order to solve the problem of the limitation of the PT symmetry region of the original WPT system based on the symmetry principle of the PT symmetry principle S-S,the S-PS topology multiload compensation system based on the PT symmetry principle is adopted.The efficient working range of the system is expanded,and the output power is increased by 50% with the proper capacitance distribution ratio.The magnetic coupler is designed to realize the decoupling between the two receiving coils,which solves the coupling interference problem between the two receiving coils.Simulations verify the effectiveness of the topological circuit,and the decoupling condition of the magnetic coupler is still available under the offset condition. Table and Figures | Reference | Related Articles | Metrics

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Comparative Analysis of China’s Energy Storage Policies During the 14th Five Year Plan Period SU Tao LOW VOLTAGE APPARATUS    2024, 0 (11): 1-9.   DOI: 10.16628/j.cnki.2095-8188.2024.11.001 Abstract （143）   HTML （10）    PDF （973KB）（67）       Knowledge map    Save Energy storage technology refers to the technological means used to store energy.During the 14th Five Year Plan period,the installed capacity of new energy generation in China continued to grow,and energy storage developed rapidly.In order to ensure the healthy and rapid development of energy storage technology,the national and local governments have successively introduced more than 100 relevant policies.The national policies are taken as the starting point for analysis,the key points of national energy storage policies are summarized,and the energy storage policies and power system development service policies are sorted out in Northeast,Northwest,North China,Central China,and South China.By comparing the differences in energy storage policies in different regions, the demand and development trends of energy storage applications are analyzed under the policy guidance in each region, the future development prospects of China’s energy storage industry are discussed,and the forward development suggestions are put forword. Table and Figures | Reference | Related Articles | Metrics

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Review of Research on Low Voltage DC Series Fault Arc WANG Yao, SHENG Dejie, LI Teng, LIU Yuying, LAN Tianle, BAO Zhizhou, ZHU Tongwei LOW VOLTAGE APPARATUS    2024, 0 (8): 11-20.   DOI: 10.16628/j.cnki.2095-8188.2024.08.002 Abstract （140）   HTML （9）    PDF （1346KB）（77）       Knowledge map    Save DC series fault arc has high concealment and difficult detection,which is an important cause of fire in low voltage DC system.The model of low voltage DC series fault arc,arc characteristics and detection methods,detection standards and devices are reviewed mainly.Based on the arc simulation model is used to understand the arc evolution process,the principle,application range and limitations of the common fault arc model are analyzed.Based on the physical and electrical signal features geuerated by fault arc,construction and detection methods the advantages and disadvantages of different feature detection methods are exponded.Finally,the relevant standards of DC series fault arc are interpreted,and the current research status and shortcomings of the test platform and products are discussed.The future research direction of low voltage DC fault arc is prospected. Table and Figures | Reference | Related Articles | Metrics

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Study on Life Prediction of Photovoltaic Inverter Based on Mission Profile YUAN Juan, CHEN Zhenghao, ZHENG Lianqing LOW VOLTAGE APPARATUS    2024, 0 (9): 1-7.   DOI: 10.16628/j.cnki.2095-8188.2024.09.001 Abstract （137）   HTML （9）    PDF （3660KB）（68）       Knowledge map    Save Taking the single-phase single-stage grid-connected photovoltaic inverters as the research object, a life prediction method of photovoltaic inverters based on mission profile was proposed.Taking the actual temperature and light intensity in a year as the mission profile, the IGBT thermal resistance model was imported into PLECS, and the junction temperature data was obtained after several thermal simulations.One year junction temperature profile of IGBT was obtained by the interpolation table lookup method, and the lifetime of individual IGBT was predicted by the rain-flow counting method and the analytical life model.Finally, the life distribution function of a single IGBT was obtained based on Monte Carlo simulation method, and the unreliability distribution function of four IGBTs of single-phase single-stage inverter was obtained by series block diagram method.The predicted results are in line with the actual situation that the service life of photovoltaic inverters is usually less than 15 years. Table and Figures | Reference | Related Articles | Metrics

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Multi-Machine Parallel Resonance Suppression Method of 125 kW PCS in Grid-Connected Operation Mode Based on Active Damping Control Strategy WU Shichao, LI Jing, ZHENG Yanbo LOW VOLTAGE APPARATUS    2024, 0 (11): 58-64.   DOI: 10.16628/j.cnki.2095-8188.2024.11.007 Abstract （136）   HTML （4）    PDF （2250KB）（50）       Knowledge map    Save Based on the popular 125 kW power conversion system (PCS) module in the current market,considering the grid impedance factor,the mathematical modeling and the impedance analysis of a single energy storage PCS and a multi-machine parallel PCS system in the grid-connected operation mode are implemented.The suppression method of multi-machine parallel resonance in the grid-connected operation mode is studied.The system side impedance of multiple PCS parallel systems is analyzed from the point of common connection,and the change of grid-connected current is analyzed by superposition principle.It is found that the coupling between the line impedance of the power grid and PCS is the key to the resonance problem of the system.The harmonic peak suppression of passive damping is analyzed,and an active damping control strategy is proposed to provide virtual damping by optimizing the capacitor current sampling feedback link.Finally,the simulation is carried out by Simulink.The results show that the THD is reduced from 9.67 % to 2.02 % under the grid-connected operation mode of 125 kW PCS multi-machine parallel system with active damping control strategy,and the resonance peak of grid-connected current is well suppressed. Table and Figures | Reference | Related Articles | Metrics

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Simulation Analysis and Experimental Verification on Static Characteristics of AC Contactor DU Qingfeng, HE Yubin, ZHANG Chao, REN Wanbin LOW VOLTAGE APPARATUS    2024, 0 (12): 10-14.   DOI: 10.16628/j.cnki.2095-8188.2024.12.002 Abstract （135）   HTML （4）    PDF （1960KB）（86）       Knowledge map    Save The calculation of static characteristics of AC contactor is the core of electromagnetic system design.Taking a type of three-phase AC contactor as an example,the finite element software COMSOL Multiphysics is applied to simulate the coil current,the flux linkage and the electromagnetic attraction under the condition of fixed magnetic gap,and the energy conversion relationship is studied through the extracted active power and reactive power.The influence of coil voltage and magnetic gap on electromagnetic attraction is analyzed.The experimental results are in good agreement with the simulation results. Table and Figures | Reference | Related Articles | Metrics

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Design and Analysis on Operating Mechanism of Smart Miniature Circuit Breakers SHENG Yongbing, TANG Fulong, ZHANG Jin, RU Dezhi, LI Junting, YUE Kang LOW VOLTAGE APPARATUS    2024, 0 (7): 50-53.   DOI: 10.16628/j.cnki.2095-8188.2024.07.007 Abstract （134）   HTML （1）    PDF （1269KB）（97）       Knowledge map    Save For smart miniature circuit breakers,a schematic diagram of the mechanism motion is drawed,the size of the four connecting rods of the operating mechanism is adjusted, and the motion trajectory of the operating mechanism is analyzed.Combined with the static analysis to analyze the force situation of the operating mechanism at certain steady-state positions,the contact parameters of the smart miniature circuit breaker (opening distance,overtravel,final pressure,driving unit force) are calculated,which provides a new design direction for the design and analysis of the operating mechanism of smart miniature circuit breakers. Table and Figures | Reference | Related Articles | Metrics

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Simulation Study on High Temperature Vibration Failure of Electrical Connector ZHU Ning, ZHAI Guofu LOW VOLTAGE APPARATUS    2024, 0 (7): 79-86.   DOI: 10.16628/j.cnki.2095-8188.2024.07.013 Abstract （133）   HTML （1）    PDF （2211KB）（57）       Knowledge map    Save The dynamic response of electrical connector in high temperature vibration environment is analyzed with Ansys software.The influence of the quality of the cable at the tail of the contact piece,temperature,separation force,stress relaxation,etc.on the micro motion amplitude is deeply analyzed.Based on the simulation,it is concluded that the original design will fail in high temperature vibration.The design of the contact positive pressure and the quality of the tail cable are optimized.Combined with the simulation analysis results and the relevant calculation,the design index range for the electrical connector to not fail under the specified high temperature vibration conditions is obtained,which means that the separation force should be as close as possible to the upper limit of 2.5 N,and the quality of the cable at the tail of each contact should be controlled within 1.2 g.The correctness of the simulation and optimization is verified by the test,which provides the design and optimization ideas for the high temperature vibration resistance of the electrical connector. Table and Figures | Reference | Related Articles | Metrics

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Safety Risk Assessment of Public Charging Infrastructure for New Energy Vehicles Based on F-score Scoring Method QIAN Yongsheng LOW VOLTAGE APPARATUS    2024, 0 (12): 63-68.   DOI: 10.16628/j.cnki.2095-8188.2024.12.011 Abstract （133）   HTML （0）    PDF （1221KB）（40）       Knowledge map    Save In order to standardize the operation and management of the public charging infrastructure,eliminate the charging safety risks and the prevent security risks.A security risk assessment method based on F-value scoring is presented.Firstly,through the investigation and analysis of the actual operation status of different types of public charging infrastructure,the typical risk points of charging infrastructure are obtained.Secondly,the safety risk assessment model of charging infrastructure is constructed,and the important evaluation indicators of charging infrastructure are determined to develop the evaluation index system.Finally,10 public charging infrastructures of new energy vehicles in Shanghai were randomly selected to carry out the safety risk assessment of charging infrastructure,and the F-value scoring method was used for comprehensive evaluation.The results show that the method has great practicability and operability. Table and Figures | Reference | Related Articles | Metrics

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Classical Making-Breaking Process Analysis of AC Contactor LI Xinye LOW VOLTAGE APPARATUS    2024, 0 (12): 57-62.   DOI: 10.16628/j.cnki.2095-8188.2024.12.010 Abstract （132）   HTML （6）    PDF （2278KB）（71）       Knowledge map    Save The main circuit voltage and current waveforms of making-breaking process of AC contactor during the electrical performance test are very important basis in analyzing on test failure reasons and making improvement measurements.The several classical waveforms of AC contactor in making-breaking test or electrical endurance test are selected to analyze.Finally,the failure modes and mechanisms corresponding to these waveforms are provided. Table and Figures | Reference | Related Articles | Metrics

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Factors Affecting Near Pole Voltage Drop of Ferromagnetic Grating in Low Voltage Circuit Breakers SUN Hao, ZHOU Liujun, ZHANG Xinyu, WU Yi, NIU Chunping LOW VOLTAGE APPARATUS    2024, 0 (8): 21-26.   DOI: 10.16628/j.cnki.2095-8188.2024.08.003 Abstract （130）   HTML （3）    PDF （1936KB）（71）       Knowledge map    Save The arc voltage in low voltage circuit breakers is directly related to the arc extinguishing performance of the circuit breaker,and the near pole voltage drop of the grating directly affects the magnitude of the arc voltage.Therefore,studying the near pole voltage drop of the grating can provide the assistance for optimizing the performance of the circuit breaker.A simplified experimental device is established,the voltage during the stable arc burning process at a DC current level of 250 A is measured,and the relationship curve between arc voltage and grating spacing is drown.The near pole voltage drop is obtained by fitting the curve.The factors affecting the near pole voltage drop are also explored from the aspects of grating material,thickness and current grade. The experimental results show that the near pole voltage drop of different materials will be different,but the grid thickness and current grade will not affect that. Table and Figures | Reference | Related Articles | Metrics

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Comparative Study on Single Pole Arc Extinguishing Capacity of Isolation Switches Under Different Usage Categories CHEN Xianzhuo, SUN Jiankun, ZHANG Senlin, ZHOU Yingzi, YAN hua LOW VOLTAGE APPARATUS    2024, 0 (6): 37-41.   DOI: 10.16628/j.cnki.2095-8188.2024.06.006 Abstract （129）   HTML （3）    PDF （5959KB）（94）       Knowledge map    Save With the continuous advancement of photovoltaic and energy storage system technology, the voltage has been raised to the mainstream of 1 500 V, and the multi pole series connection is usually used to meet the demand for continuous voltage increase, resulting high cost, large volume, and certain limitations in the use category of existing DC isolation switch products. Therefore, a discussion is conducted on the operating conditions of DC isolation switch products, analyzing the differences in expected current waveforms under different time constants, proposing an improved arc extinguishing chamber structure, and analyzing the experimental results caused by the differences in arc extinguishing capacity of isolation switch products under different usage categories, providing new insights for enhancing the applicability of switch products in voltage systems that are continuously being upgraded. Table and Figures | Reference | Related Articles | Metrics