Table of Content

30 October 2024, Volume 0 Issue 10

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Research & Analysis

Displacement Control Strategy of AC Contactor Based on Sensorless Technology

ZHANG Junhui, LIU Shuxin, LIU Yang, XING Chaojian

2024, 0(10):  1-6.  doi:10.16628/j.cnki.2095-8188.2024.10.001

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Aiming at the problems of low reliability and poor precision of traditional contactor control model,a dynamic simulation and analysis method of AC contactor suction process based on sensorless technology is proposed.Firstly,according to the magnetic circuit model of AC contactor,the displacement formula of moving iron core of AC contactor is deduced,and the displacement estimator is formed.Based on the displacement estimator,the suction force is predicted,and a closed-loop controller is designed according to the control model.Then,the dynamic closed-loop control simulation model of AC contactor is established,and the closing time of AC contactor in three modes of uncontrolled,PWM time-sharing control and displacement feedback closed-loop control is compared and analyzed,which proves that the displacement closed-loop control scheme has remarkable effectiveness.Finally,the experimental results confirm the accuracy of the model and the practicability of the control strategy,and provide some ideas for the intelligent control of AC contactor.

Electrical Life Prediction Method of DC Circuit Breaker Based on Residual Network Regression

YANG Nuoming, WU Ziran, LIU Zezhou, WU Chenxi, WU Guichu, LIN Yigang

2024, 0(10):  7-18.  doi:10.16628/j.cnki.2095-8188.2024.10.002

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According to the breaking characteristics of DC arc,a method for predicting the electrical life of DC circuit breaker is proposed.According to the standard GB/T 14048.2—2020,the voltage waveform during the breaking process is obtained.After CEEMDAN filtering,the voltage signal within a period of arc break is used as the network training sample.The contact mass is used to represent the electrical life condition,and the contact mass decline curve is obtained by linear interpolation,which is used as the network training label.A one-dimensional convolutional structure prediction model of residual network(ResNet)is constructed using Pytorch framework.The experimental results show that the prediction error of the prosed method is less than 10%,which proves that the method can be used to predict the electrical life under GB/T 14048.2—2020 standard.

Calculation and Analysis of Switch Closing Speed and Short-Circuit Closing Capacity

ZHANG Anming, ZHOU Qiang

2024, 0(10):  19-25.  doi:10.16628/j.cnki.2095-8188.2024.10.003

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Short-circuit closing capacity is an important performance of the switch.The main factors of affecting the short-circuit closing capacity are analyzed.With the method of electro-magnetic simulation and calculation formula,the closing speed and short-circuit closing capacity of the switch are calculated and analyzed.Finally,the feasibility of the design and calculation analysis is verified by the short-circuit closing capacity test of DC 70 kA,which has a great engineering significance.

Study on Improving Critical Load Current Breaking Ability of Miniature Low Voltage DC Circuit Breaker with Permanent Magnet

ZONG Yueju, LI Jing, JIANG Song, GAN Yunjian

2024, 0(10):  26-30.  doi:10.16628/j.cnki.2095-8188.2024.10.004

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When the small low voltage DC circuit breaker breaks the critical load current,it is difficult to break the circuit because of the weak effect of magnetic blowing and gas blowing on the arc.A permanent magnet is added at the corner of the static contact assembly.Through analyzing the quenching mechanism of miniature low voltage DC circuit breaker,the magnetic field simulation and test verification of miniature low voltage DC circuit breaker before and after adding permanent magnet are carried out.The results show that the addition of permanent magnets can enhance the magnetic field intensity at the position of the arc,increase the Lorentz force of the arc,and help the miniature low voltage DC circuit breaker to improve the ability of breaking the critical load current.

Partial Discharge Analysis on Inner Cone Casing of Built-in EVT in Primary and Secondary Fusion Ring Cabinet

LI Yanyan, ZHENG Xiaoguo

2024, 0(10):  31-35.  doi:10.16628/j.cnki.2095-8188.2024.10.005

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In order to solve the partial discharge problem of the EVT inner cone casing in the primary and secondary fusion ring cabinet,the electrostatic field analysis is carried out first to extract the electric field distribution in the area with relatively concentrated electric field.Then according to the high voltage electrode voltage sharing technology and the gas-solid composite insulation theory,the structure of the EVT center copper rod,the shape of the EVT end and the matching clearance with the high pressure end face of the casing are optimized.After optimization,the maximum field strength along the three interfaces of the EVT inner cone casing is reduced from 2.85 kV/mm to 1.75 kV/mm,and the maximum field strength at the end of the casing is reduced from 3.90 kV/mm to 2.35 kV/mm.The feasibility of the method is verified theoretically.The partial discharge test shows that the local discharge quantity is reduced from 42.54 pC to 1.05 pC after optimization,which proves the practical feasibility of the method,and provides a favorable guidance for the research and development of the composite insulation structure related to the quasi-primary and secondary fusion of 10 kV and higher voltage levels.

Research on Partial Discharge Diagnosis Algorithm for Cable Accessories Based on Multi Sensor Information Fusion

LIU Hao, HOU Chunguang, GAO Youhua

2024, 0(10):  36-41.  doi:10.16628/j.cnki.2095-8188.2024.10.006

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A partial discharge diagnosis algorithm for cable accessories based on multi-sensor information fusion is proposed to solve the relative questions.An experimental platform is built.The transient earth voltage sensors(TEV),high-frequency current sensors(HFCT),and ultrasonic sensors(AA)are used to collect multimodal data of partial discharge in cable accessories.A partial discharge phase distribution(PRPD)feature mapis draw.A dataset for partial discharge is constructed.The convolutional neural network(CNN),backpropagation neural network(BPNN),and support vector machine(SVM)algorithms are used for classification and recognition to obtain the recognition credibility of the three algorithms.The intelligent fusion algorithm is obtained through the credibility fusion,and the recognition results show that the intelligent fusion algorithm exhibite high recognition accuracy in the different scenarios to improve the accuracy and reliability of partial discharge diagnosis of cable accessories.

Detection & Experiment

Research on Measurement Method for Output Junction Capacitance of Semiconductor Devices Based on Transient Switching Oscillation Process

LI Haoyang, ZHENG Yanwen, LI Hao, CHEN Ruiwen, HU Sideng

2024, 0(10):  42-47.  doi:10.16628/j.cnki.2095-8188.2024.10.007

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The output capacitance of semiconductor devices exhibits nonlinear changes with increasing voltage.In order to accurately extract the output junction capacitance under high voltage operating conditions,a measured method for the output junction capacitance of semiconductor devices based on the transient switching oscillation process is proposed.Firstly,the mathematical relationship between the high frequency oscillation frequency of device turnoff transient excitation and the junction capacitance are explored,and the corresponding extraction steps is formed.Secondly,the factors affecting the accuracy are discussed from the perspectives of parasitic inductance and parasitic resistance.Finally,a testing platform is built and the extraction results of semiconductor devices of different models and packages are verified.The experiment shows that the proposed method can extract the output junction capacitance value at the rated operating point of the device,and has advantages such as high testing consistency and strong scalability.

Experimental Study on AC Arc Characteristics of Rocker Switches

LU Siyu, ZHANG Chao, QIU Jun, HE Yubin, REN Wanbin

2024, 0(10):  48-52.  doi:10.16628/j.cnki.2095-8188.2024.10.008

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The AC arc characteristic curve is an important basis for evaluating the breaking capacity of switches.The influence of magnetic blowing on AC arc characteristics is analyzed by testing the contact voltage and contact current waveforms during the breaking process of rocker switch.It is confirmed that there are two arc extinguishing mechanisms,which are the mechanical breaking mechanism and the current zero-crossing mechanism.The drawn conclusion is valuable for improving the AC load breaking capacity of rocker switches.

Design and Experimental Analysis on Testing System for Closing-Opening Operation of MCB

XIE Zhenhua, WANG Zheng, HE Puquan, HUANG Huigen, LIU Guiqin

2024, 0(10):  53-58.  doi:10.16628/j.cnki.2095-8188.2024.10.009

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In order to address the shortcomings of existing pneumatic testing devices used to execute mechanical and electrical life tests of MCB in the laboratory,such as uncontrollable speed and easily making handles damaged,as well as too simple operation path which is not sufficient to perform all MCBs’ handle closing,a test system for the closing and opening operation of MCB is designed.The system achieves the closing operation of the product handle with a stable and controllable speed and curved motion trajectory through three-axis motion control.The product has wider applicability.By installing a force sensor on the end effector,the real-time monitoring of the closing force during the closing and opening of the test handle can be achieved.By carrying machine vision,the intelligent acquisition of operation position of the test samples can be achieved.The experimental results show that the proposed test system can monitor the changing force with different characteristics in the different closing operations,and the arc-shaped closing speed of the test system can meet the requirements of national standards.

Simulation Technology Application

Thermal Analysis and Improvement Method Research on High Voltage Full Film Capacitor

YE Zetao, LI Xiaojun, ZHENG Yanwen, HU Chenhao, HU Sideng

2024, 0(10):  59-64.  doi:10.16628/j.cnki.2095-8188.2024.10.010

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Mastering the distribution law of temperature field is an important link and technical difficulty in enhancing the stable operational performance of capacitors.Combined the structural characteristics of a certain type of high voltage full film capacitor,using the finite volume method to solve the three-dimensional temperature field distribution,the hottest temperature and corresponding position is obtained inside the complex capacitor,and its temperature parameters and distribution characteristics are studied.On this basis,in order to enhance the heat dissipation capacity of the capacitor,the improvement plans are proposed by adding new heat dissipation channels and increasing the thickness of component aluminum foil.The study indicates that the used three-dimensional temperature field analysis can accurately reflect the internal temperature characteristics of the capacitor,and the proposed improvement measures can effectively reduce the temperature of breakdown points by 33.6%.

Simulation Study of DC Circuit Breaker Magnetic Release Characteristics Based on Saturation Magnetic Circuit

HAN Wei, ZHU Zhongjian, YI Chenchen, MENG Fanfei, QIU Zhongjun, XI Jie

2024, 0(10):  65-71.  doi:10.16628/j.cnki.2095-8188.2024.10.011

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The magnetic release is the key component of DC circuit breaker,which directly determines the short circuit protection performance of DC circuit breaker.The magnetic release based on saturation magnetic circuit is modeled and simulated to obtain the magnetic curve of different currents,and the characteristics of the magnetic release based on saturation magnetic circuit are compared with the traditional single magnetic circuit magnetic release.The results prove that the magnetic release based on saturation magnetic circuit has higher release accuracy and operation reliability,which provides a basis for the design and optimization of magnetic release.

Design and Simulation Analysis of Magnetic Adjustable Electromagnetic Release

LI Xiankai, LU Chunrong, GAN Jiaqi

2024, 0(10):  72-78.  doi:10.16628/j.cnki.2095-8188.2024.10.012

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In power distribution systems,molded case circuit breaker(MCCB) play a role in protecting the short-circuit current of line.However,when using this traditional tripping method(screw tube type and rotary snap on type) to achieve protection against short-circuit current,the power distribution structure cannot flexibly change with the load.Therefore,the design points of the structure of the magnetic adjustable electromagnetic release is described.Based on Ansys software,the static and dynamic characteristics of the electromagnetic release are analyzed,and the design results are verified through simulation examples and experiments.The reliability of the magnetic adjustable electromagnetic release is verified,and the overcurrent protection performance of the molded case circuit breaker is improved.