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Research on Improving Short Circuit Breaking Capacity of 125 A Miniature MCCB HUANG Yinfang, JIANG Guping LOW VOLTAGE APPARATUS    2023, 0 (11): 53-58.   DOI: 10.16628/j.cnki.2095-8188.2023.11.009 Abstract （410）   HTML （35）    PDF （2058KB）（884）       Knowledge map    Save Molded case circuit breakers (MCCB) below 125 A are main force in the field of MCCBs.The main way to integrate and improve them is to elevate 63 A and 100 A products to 125 A with short circuit breaking being the main difficulty.It is possible to preliminarily increase its breaking capacity through gas producing materials.Quantified data analysis can be conducted on the condition of the arc extinguishing chamber’s grid segments through the measurement and analysis of grid voltage.The simulation of electromagnetic force is used to optimize the magnetic field of the contact part.By improving the design, the new 125A product can replace the original product and meet the performance requirements while reducing the cost of the main product. Table and Figures | Reference | Related Articles | Metrics

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Research on Backflow Power Optimization Strategy for Dual-Active-Bridge DC-DC Converter KANG Zhiwei, XU Yuzhen LOW VOLTAGE APPARATUS    2023, 0 (10): 14-20.   DOI: 10.16628/j.cnki.2095-8188.2023.10.003 Abstract （260）   HTML （4）    PDF （2177KB）（97）       Knowledge map    Save Aiming at the value of the backflow power of dual-active-bridge DC-DC converter is too large during power transmission, based on the dual-phase-shift control, the segmented optimization control strategy is proposed to optimize the backflow power. In the control strategy, the whole output power is divided by defining the power segmentation point. When the output power is lower than the power segmentation point, zero backflow power operation is realized.When the output power is higher than the power segmentation point, the minimum backflow power operation is realized. Finally, a 250 W experimental prototype is built. The experimental results show that compared with the traditional phase shift control method, the segmented optimization control strategy can effectively reduce the backflow power of the dual-active-bridge DC-DC converter and improve the efficiency of the circuit. Table and Figures | Reference | Related Articles | Metrics

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Primary Frequency Control Strategy for Inverter Air Conditioner Considering User Behavior LIU Meiyan, WANG Juanjuan LOW VOLTAGE APPARATUS    2023, 0 (10): 21-27.   DOI: 10.16628/j.cnki.2095-8188.2023.10.004 Abstract （252）   HTML （2）    PDF （1871KB）（57）       Knowledge map    Save With the development of power system, the stable operation of frequency is facing great challenges, and the cost of generation side is also increasing rapidly. In order to address the many adverse effeds faced by the power grid and involve the load side in power grid frequeney regulation, a hierarchical control strategy of inverter air conditioner participating in primary frequency modulation based on improved droop control is proposed. According to the characteristics of inverter air conditioner, the aggregation model based on the first-order physical model is established, and the droop control model is improved.Considering the state of indoor temperature with air-conditioner (SOA) and the comfort of users, an orderly participation response control strategy of inverter air conditioners based on SOA priority list is established. It can efficiently dispatch inverter air conditioners and adjust the frequency. Table and Figures | Reference | Related Articles | Metrics

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Short-Term Photovoltaic Output Prediction Based on CEEMDAN and Improved LSTM HUANG Junzhe, YIN Yuhan, TANG Mingxuan, MEI Fei LOW VOLTAGE APPARATUS    2023, 0 (10): 36-43.   DOI: 10.16628/j.cnki.2095-8188.2023.10.006 Abstract （242）   HTML （7）    PDF （2490KB）（85）       Knowledge map    Save In order to improve the accuracy of photovoltaic output power prediction, a model that combines complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) algorithm with improved long short-term memory (LSTM) neural network is proposed to predict short-term photovoltaic power. Firstly, the photovoltaic power sequence is decomposed by CEEMDAN algorithm and the subsequence components are obtained. Then, improved LSTM neural network is used to predict each subsequence component. Particle swarm optimization (PSO) algorithm is used to optimize the number of hidden layer neurons, learning rate and training times of LSTM neural network. The attention mechanism is used to optimize the probability distribution in the process of training LSTM neural network. Finally, the final predicted value is obtained by adding the predicted results of each subsequence component. Example analysis shows that prediction evaluation indexes of the proposed model MAE, RMSE and R2are all the best by comparison with other algorithms, which can verify the superiority of the proposed model. Table and Figures | Reference | Related Articles | Metrics

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Effect and Optimization on Short-Circuit Breaking Performance for MCB Shell Modification from Thermosetting to Thermoplastic CHEN Changzu, ZHOU Chao, JIN Pingping LOW VOLTAGE APPARATUS    2024, 0 (5): 53-60.   DOI: 10.16628/j.cnki.2095-8188.2024.05.007 Abstract （231）   HTML （4）    PDF （2370KB）（128）       Knowledge map    Save Aiming to study the influence of shell material characteristics (such as mechanical strength,high-temperature arc resistance,gas production and dielectric recovery strength) and shell structure on short-circuit breaking ability,based on the design of the miniature circuit breaker (MCB) shell material modifying from a thermosetting bulk molding compound (BMC) to a thermoplastic PA6 and the characteristics of a PA6 material,the shell structure is optimized.The short-circuit breaking test is carried out through the combination of different shell material and structure,then the testing data is obtained.Based on the test data and the disassembly information after testing,the relationship of the distribution and stability of arc time and energy in each stage of short-circuit breaking with the shell material and structure is studied by dividing the arc stages,the structure of a PA6 shell MCB is optimized.Finally,the short-circuit breaking test is passed.The experimental results show that the structure optimization of the thermoplastic modification is reasonable,which indicates that the analysis method of short-circuit breaking test is effective and has certain reference significance for the design and analysis of similar products. Table and Figures | Reference | Related Articles | Metrics

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Analysis of Dynamic Characteristics Influencing Factors of Rapid Repulsion Mechanism in Demagnetization Switch DONG Li, MA Shaohua LOW VOLTAGE APPARATUS    2023, 0 (10): 8-13.   DOI: 10.16628/j.cnki.2095-8188.2023.10.002 Abstract （216）   HTML （8）    PDF （2537KB）（99）       Knowledge map    Save In order to improve the breaking speed of the rapid repulsion mechanism and meet the requirements of demagnetization switch applications, the finite element method is used to establish a two-dimensional axisymmetric model of the rapid repulsion mechanism with Maxwell electromagnetic simulation software according to the dynamic characteristics requirements of the demagnetization switch for the rapid repulsion mechanism. The effects of the thickness, radius, material, spacing, coil turns, capacitance, and voltage of the repulsive disk on the dynamic characteristics of the rapid repulsion mechanism are analyzed through simulation. The results show that the optimizing relevant parameters can improve the dynamic characteristics of the fast repulsion mechanism, and the simulation results provide guidance for the prototype design of the fast repulsion mechanism. Table and Figures | Reference | Related Articles | Metrics

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Review of Research on Remaining Useful Life Prediction of Relays Based on Deep Learning LI Shaofei, WANG Zhaobin, ZHANG Wenhang LOW VOLTAGE APPARATUS    2023, 0 (10): 1-7.   DOI: 10.16628/j.cnki.2095-8188.2023.10.001 Abstract （208）   HTML （8）    PDF （1268KB）（124）       Knowledge map    Save Studying the reliability of individual relays is of great significance. Therefore, it is necessary to predict the lifespan of relays. Due to the excessive reliance of traditional prediction methods on the equipment domain knowledge, the deep learning is applied to the field of life prediction. Firstly, the storage failure mechanism of relays is summarized. Secondly, the current research status of relay remaining useful life prediction is introduced. Then, several common model methods and their characteristics of deep learning are analyzed. Finally, the application of deep learning in the remaining useful life prediction is prospected. Table and Figures | Reference | Related Articles | Metrics

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Research on Key Technology of Low Voltage DC Solid State Circuit Breaker WU Xin, TAO Chuangchuang, WANG Jingshuai, WU Yifei, WU Yi LOW VOLTAGE APPARATUS    2024, 0 (1): 1-5.   DOI: 10.16628/j.cnki.2095-8188.2024.01.001 Abstract （201）   HTML （18）    PDF （2568KB）（158）       Knowledge map    Save Compared with the mechanical circuit breakers,the solid-state circuit breakers have been widely focused for their advantages such as the faster breaking speed and higher lifetime.A low-voltage DC solid-state circuit breaker topology and operating principle based on SiC devices is introduced,and the technical difficulties of solid-state circuit breakers are analyzed,including the low-inductance package and device design,the isolated switch technology and the fast fault identification technology.A prototype of ±375 V DC solid-state circuit breaker is developed and tested for the fault current breaking and the temperature rise.The results show that the DC solid-state circuit breaker can achieve 1 kA short-circuit current breaking within a hundred microseconds.In addition,the prototype is equipped with the functions such as the fast fault identification,the programmable protection curve,the external communication and the remote control. Table and Figures | Reference | Related Articles | Metrics

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Analysis and Research on Key Component Characteristics of ACB Based on NX Motion Simulation PAN Xuan, LI Tao, HOU Kui, LIU Fengfeng LOW VOLTAGE APPARATUS    2023, 0 (8): 76-82.   DOI: 10.16628/j.cnki.2095-8188.2023.08.012 Abstract （200）   HTML （4）    PDF （1850KB）（121）       Knowledge map    Save Energy storage process, closing process and opening process of operating mechanism and contact system in series ACB products are simulated and studied based on Motion modular. Firstly, a three-dimensional model is established through UG. Using arrangement function, three initial states are built as the dynamic model of the three processes. Secondly, according to the actual motion relationship, the dynamic parameters are set up. Dynamic motion characteristics are got, including force value, time value, torque value and so on after solving. The influence of the main structural parameters of the operating mechanism and contact system on the motion characteristics is analyzed.According to analysis result, mechanism will not occur false closing, and closing time can be controlled in 10 ms.According to compare to test data, the correction of dynamic model and simulation results can be ensure. On this basis, the key parameters setting and matters needing attention during simulation process are summarized, which can supply responsible approach to optimal design and characteristics improvement. Table and Figures | Reference | Related Articles | Metrics

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Design of Safety Fire Switch for Photovoltaic Module HE Jiajun, BAO Guanghai LOW VOLTAGE APPARATUS    2023, 0 (7): 42-47.   DOI: 10.16628/j.cnki.2095-8188.2023.07.007 Abstract （198）   HTML （10）    PDF （2559KB）（110）       Knowledge map    Save A fire safety switch based on carrier communication is designed to address the fire safety issues of photovoltaic modules.The specific design of the breaker and the controller are carried out.The circuit breaker collects the voltage and current data of each PV module,transmits them to the controller via power line carrier communication,and then uploads them to the PV system monitoring platform via RS-485 to display the operation status of the PV module in real time.In addition,the PV module can be turned off through the PV system monitoring platform or manually pressing the shutdown button on the controller,which can greatly reduce the high voltage on the DC side of the PV in case of fire to ensure the personal safety. Table and Figures | Reference | Related Articles | Metrics

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Design on Operating Mechanism Key Parameters of Moulded Case Circuit Breaker LI Peng LOW VOLTAGE APPARATUS    2024, 0 (3): 47-52.   DOI: 10.16628/j.cnki.2095-8188.2024.03.008 Abstract （196）   HTML （14）    PDF （2194KB）（148）       Knowledge map    Save On the basis of briefly describing the action principle of the operating mechanism of the moulded case circuit breaker (MCCB),a certain model of double break point MCCB is taken as the design and research object.Using ADAMS analysis software,the important parameters of the operating mechanism,such as the three elements of the contact,the opening and closing speed of the contact,the opening and closing force of the mechanism,the opening and closing stroke,and the opening and closing time,are calculated.The simulation parameters have minimal error compared to the measured parameters of the prototype.The allowance between the simulated parameters and the measured parameters of the prototype is very small.A design method of the operating mechanism key parameters is provided. Table and Figures | Reference | Related Articles | Metrics

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Mechanism Analysis and Maintenance Research on Deterioration of Aircraft Contactor Contact MENG Xin, SUN Qihai, YU Chunfeng, ZHANG Yuanfeng LOW VOLTAGE APPARATUS    2023, 0 (7): 30-35.   DOI: 10.16628/j.cnki.2095-8188.2023.07.005 Abstract （192）   HTML （5）    PDF （2022KB）（103）       Knowledge map    Save The contactor failure caused by the contact adhesion of aircraft contactor occurs frequently,and the harsh environment makes the contact life of the contactor far lower than the ideal life,which brings great difficulties to the field maintenance work.It is of great significance to study the deterioration mechanism of the contact surface of the contactor under the field conditions to formulate the maintenance plan,improve the maintenance quality and ensure flight safety.The contact surface states from macro and micro angles are observed,the composition of contact spot elements is analyzed,and the fault mechanism of contact resistance increasing in combination with the characteristics of aircraft contactor working environment is researched.Taking the existing misunderstandings and hazards in the current field contactor contact maintenance,the field inspection and maintenance improvement scheme of the contact are studied,which can help the maintenance personnel master the health status and remaining life of the contactor and achieve the purpose to reduce the failure rate of the contactor. Table and Figures | Reference | Related Articles | Metrics

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Neutral Point Voltage Balance Control of Type-I Three-Level PCS ZHANG Xiaojie, MAO Xingkui, ZHENG Jiadong, ZHANG Zhe, DONG Jiqing LOW VOLTAGE APPARATUS    2023, 0 (9): 18-23.   DOI: 10.16628/j.cnki.2095-8188.2023.09.003 Abstract （191）   HTML （2）    PDF （2156KB）（55）       Knowledge map    Save In response to the inherent neutral point voltage imbalance problem in type-I three-level power conversion system (PCS),the principle of neutral point voltage imbalance is analyzed based on space vector modulation,and a hybrid modulation strategy is proposed combining seven segment space vector pulse width modulation (SVPWM) with five segment SVPWM.When the neutral point voltage offset is large,the seven segment SVPWM with balance factor is used to quickly adjust the neutral point voltage.When the neutral point voltage offset is small,the five segment SVPWM without switching at high current is adopted to effectively reduce the switching times of the switch and reduce the loss.A 12 kW PCS prototype is built.The experiments show that compared with the traditional seven segment SVPWM,the neutral point voltage offset and fluctuation of the hybrid modulation strategy is reduced,and the efficiency of the prototype is improved by about 0.3%.The correctness and effectiveness of the proposed hybrid modulation strategy are verified. Table and Figures | Reference | Related Articles | Metrics

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Arc Simulation and Performance Optimization of Non-Polar Low Voltage DC Circuit Breaker Based on Magnetohydrodynamics WEN Hui, GUO Xiaoxue, ZENG Xinyi LOW VOLTAGE APPARATUS    2024, 0 (2): 6-12.   DOI: 10.16628/j.cnki.2095-8188.2024.02.002 Abstract （191）   HTML （8）    PDF （1864KB）（140）       Knowledge map    Save In response to the problem that traditional low voltage DC circuit breakers weaken their arc extinguishing ability when the current is reversed due to the unidirectional magnetic field, the arc simulation model of non-polar low-voltage Dc circuit breaker based on COMSOL is established to analyze the arc motion of non-polar low-voltage Dc circuit breaker under the reverse current. The influence of magnetic field and current on the arc-extinguishing ability of non-polar low-voltage Dc circuit breaker is analyzed. The simulation results show that the non-polar low-voltage Dc circuit breaker can eliminate the blocking effect of current reversal on arc motion, and the arc extinguishing ability is strongest at 240 mT and 16 A. In addition, the simulation results are consistent with the experimental results. The arc-extinguishing ability of the non-polar low-voltage Dc circuit breaker is the strongest in the appropriate magnetic field, and the smaller the current is, the strongest arc extinguishing ability. Table and Figures | Reference | Related Articles | Metrics

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Simulation Analysis and Experimental Research on Contact System of Fast Earthing Switch Based on Explicit Dynamics XU Minhang, LÜ Pengrui, CUI Aiqiang LOW VOLTAGE APPARATUS    2023, 0 (7): 18-24.   DOI: 10.16628/j.cnki.2095-8188.2023.07.003 Abstract （189）   HTML （4）    PDF （2048KB）（109）       Knowledge map    Save Fast earthing switch (FES) is a kind of electrical equipment that provides fast earthing protection.It is often used in power equipment such as medium voltage switchgear to prevent electrical equipment from being damaged by the internal arc faults.According to the development status and engineering application requirements of its contact mechanism design,the contact system collision of FES is studied.Firstly,the transient process of the conical contact system of FES in high-speed collision is analyzed based on the explicit dynamics,and the main parameters affecting the contact system’s action characteristics are identified.Secondly,the structure parameters of the static contact are optimized by using the multi-objective optimization module of Ansys Design Xplorer.Finally,the high-speed collision test is carried out to verify whether the contact system meets the design requirements.The results show that the conical contact system has good dynamic characteristics and can form a stable electrical contact surface during the fast closing process,which can meet the application requirements of FES. Table and Figures | Reference | Related Articles | Metrics

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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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High-Efficiency Totem Pole PFC Circuit Design Based on GaN Devices ZHENG Runmin, LI Tang, MAO Xingkui LOW VOLTAGE APPARATUS    2023, 0 (11): 41-47.   DOI: 10.16628/j.cnki.2095-8188.2023.11.007 Abstract （188）   HTML （3）    PDF （2350KB）（80）       Knowledge map    Save GaN devices are widely used in totem-pole bridgeless PFC circuits due to their excellent switching performance.In the inductor current critical continuous mode (CRM), Totem-Pole bridgeless PFC can achieve soft switching of the switching tube across the full input voltage range through the reasonable control.In view of the problem of complex control timing for the control mode based on the traditional current zero-crossing detection (ZCD) circuit, a soft switching control strategy based on the current state detection circuit is proposed to reduce the complexity of control.The design pressure of the EMI filter is reduced by adopting an interleaved parallel structure, and the power inductances of the two-phase circuit are integrated by using decoupling magnetic integration technology.Finally, a 3 000 W GaN-based interleaved bridgeless totem-pole PFC rectifier is built.The effectiveness of the proposed circuit design scheme is verified by experiments. 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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Short Circuit Testing System for DC Circuit Breaker Used in Communication HUANG Fang, ZHANG Liqian, ZHANG Yan LOW VOLTAGE APPARATUS    2023, 0 (10): 49-53.   DOI: 10.16628/j.cnki.2095-8188.2023.10.008 Abstract （183）   HTML （3）    PDF （2244KB）（84）       Knowledge map    Save Based on the rated DC operating voltage characteristics of communication DC circuit breakers, a short-circuit testing system for communication DC circuit breakers is designed using a large capacity multi magnetic circuit transformer. The system adopts the built-in rectifier circuit and the regulating impedance nearby, the independent control systems and mobile measurement systems to test a maximum short-circuit current capacity of 25 kA for rated voltage DC 100 V and below, which can be suitable for short-circuit testing of communication DC circuit breakers. Table and Figures | Reference | Related Articles | Metrics

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Analysis on Bounce Characteristics of Cu-W Composite Contact with Micro-Oriented Structure HAN Ying, HUANG Xin, LIU Dongrui, HOU Chunguang LOW VOLTAGE APPARATUS    2023, 0 (8): 1-9.   DOI: 10.16628/j.cnki.2095-8188.2023.08.001 Abstract （183）   HTML （6）    PDF （4114KB）（97）       Knowledge map    Save The commercial disordered structure Cu-W contact and three kinds of micro-oriented Cu-W composite contacts were taken as the research object. Through the establishment of contactor contact bounce dynamics model, the electromagnetic model and the contact mechanics model, the machine-electric-magnetic multi-physics coupling simulation analysis of the contactor was implemented. The stress-strain difference of the three micro-oriented structure and commercial disordered structure Cu-W contact under load was studied. The influence of the three micro-oriented structure and commercial disordered structure Cu-W contact on contact bounce was analized and verified through experiment. The micro-oriented structure contact was found to have smaller bounce amplitudes and shorter bounce times. The results show that compared with commercial disordered structure Cu-W contacts, the micro-oriented Cu-W composite contacts have better bounce resistance, and Cu-W contact with the rhombic dodecahedron frame structure possess the best anti-bounce characteristics. Table and Figures | Reference | Related Articles | Metrics