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Table of Content

    30 October 2021, Volume 0 Issue 10
    Overview
    Analysis of Energy Development in Europe and Its Implication for Carbon Neutrality
    ZHENG Zhanghua, NI Yufan, FENG Limin, ZHANG Shengxiang, WANG Xin
    2021, 0(10):  1-6.  doi:10.16628/j.cnki.2095-8188.2021.10.001
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    This paper analyzed the energy consumption and supply in Europe since 1990,and discussed the main paths of European energy development and decarbonization.The potential enlightenment for China to achieve carbon neutrality that suits the best its own conditions and realities is discussed.

    Research & Analysis
    Research on Prestrike Characteristics of Double-Break VCB Under Direct Current Voltages
    PENG Jing, DENG Yunkun, WANG Ke, CHEN Xinggui, GENG Yun, GENG Yingsan
    2021, 0(10):  7-12.  doi:10.16628/j.cnki.2095-8188.2021.10.002
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    The purpose of this paper is to study the prestrike characteristics of a double-break vacuum circuit breaker under direct current voltages.In this experiment,we measured the prestrike gap of the single-break and the double-break vacuum circuit breaker in closing operations under different voltage levels,and calculated their Weibull probability distribution.The results show that,compared with the 50% prestrike gap of the single-break vacuum circuit breaker,the d50 of each vacuum interrupter in the double-break vacuum circuit breaker is reduced by 25.0%~72.7%.Due to the voltage sharing effect of double-break vacuum breaker,the dispersion of the prestrike gaps of the vacuum interrupters in the high voltage side and low voltage-side of double-break vacuum breaker is significantly lower than that of the single-break vacuum circuit breaker.

    Short-circuit Current Frequency Measurement and Zero Prediction Method Based on Least Square Correlation Coefficient
    ZOU Dewei, WANG Liantie, MENG Yu, MA Shaohua
    2021, 0(10):  13-17.  doi:10.16628/j.cnki.2095-8188.2021.10.003
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    The actual frequency of the power grid is measured based on the principle of maximum linear correlation coefficient of the least square method,and the power grid actual frequency is used to construct the least square method coefficient matrix,and then the characteristic parameters of the short-circuit current are identified,based on which the zero-crossing point of the short-circuit current is predicted.The simulation results show that the method can effectively measure the actual frequency of the power grid,and can eliminate the short-circuit current characteristic parameters and zero prediction errors caused by asynchronous sampling frequency offset.

    Primary Frequency Modulation Control of DFIG Based on Optimization and Coordination of Overspeed and Variable Paddle
    ZHANG Liusheng, XIE Zhen, Xu Kebao, ZHANG Xing
    2021, 0(10):  18-27.  doi:10.16628/j.cnki.2095-8188.2021.10.004
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    With the increasing of the grid-connected capacity of wind power,the new energy generation system puts forward higher requirements for wind power to participate in frequency modulation.Because the doubly-fed wind turbines the active power and frequency are decoupled,the active standby power supporting the grid frequency control cannot be provided.Therefore,load reduction is carried out and part of active power is reserved in advance as standby for frequency modulation.However,overspeed and paddle change control have certain limitations under different wind conditions.In this paper,a primary frequency modulation control strategy based on optimal coordination of overspeed and variable paddle is proposed to adapt to the full wind speed condition.The optimal combination of overspeed and variable paddle is studied to adjust and coordinate controller parameters under different wind conditions to release standby power stably.The simulation results show that the optimization and coordination control method proposed in this paper has better frequency modulation performance than the existing method,can reduce wind abandon better.

    Accelerated Degradation Test and Reliability Evaluation of Lithium Thionyl Chloride Battery for Smart Electricity Meter
    SUN Qisen, LI Haoxiang, YE Xuerong, ZHAI Guofu
    2021, 0(10):  28-32.  doi:10.16628/j.cnki.2095-8188.2021.10.005
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    Lithium thionyl chloride batteries are used as key backup power sources for instruments and other equipment,and their capacity status directly affects the operational reliability of equipment and systems.Aiming at the problem that the life and reliability of lithium thionyl chloride batteries are difficult to evaluate or the evaluation accuracy is low under actual working conditions of smart meters,this paper proposes an accelerated degradation test,capacity degradation modeling,and battery reliability evaluation methods.The semi-failure physical degradation model used in this paper can accurately describe the capacity degradation trend,combined with battery capacity dispersion,can evaluate the reliability of lithium thionyl chloride batteries,and provide a reference for predicting battery life under actual operating conditions.

    Research on Discharge State Estimation Method of Retired Power Battery
    YAN Hu, HU Jing, WANG Zhe
    2021, 0(10):  33-41.  doi:10.16628/j.cnki.2095-8188.2021.10.006
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    Based on the existing battery characteristics data,this paper uses entropy value method to calculate the weight of the battery characreristics,and then uses the grey correlation analysis method to calculate the correlation between the battery character is tics,and lastly takes the dischargeable capaeity of retired power battery as indicators of discharge stare estimation,combining support vector machine (SVR) and particle swarm optimization(PSO) to establish the index evaluation model.Fially,the chargeng and discharging test of the rerired power bactery verifies the effectiveness of the method.The test results show that the estimation method can be used for retired power battery status tracking.

    Electrical Design & Discussion
    Simulation and Experimental Research on Current Injection DC Circuit Breaker
    CHEN Lingling, WANG Kun, ZHOU Chunlong
    2021, 0(10):  42-47.  doi:10.16628/j.cnki.2095-8188.2021.10.007
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    In order to solve the rated breaking current impact and long breaking time of small current of the conventional current injection type DC circuit breaker,IGCT branch is connected in parallel at both ends of the current injection DC circuit breaker to achieve rated current breaking,and through forced commutation to achieve short-circuit current breaking.Aiming at the secondary zero-crossing phenomenon of the fast vacuum switch during the 60 kA short circuit breaking process,the influence of the zero-crossing rate of the arcing current and the distance at the zero-crossing time of the fast vacuum switch on the zero-crossing cut-off is analyzed,on this basis,improvement measures are proposed.The effectiveness of the measures and the feasibility of practical application are verified through simulation and experiments.

    Analysis and Research on Design of Amplifying Mechanism of Electronic Residual Current Release
    HUANG Jia, REN Changbin, SHI Keshao, PAN Chang
    2021, 0(10):  48-51.  doi:10.16628/j.cnki.2095-8188.2021.10.008
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    Aiming at the problem of leakage function failure caused by too large tripping force of circuit breaker,the output force of residual current release,as the key parameter of electronic residual current device(RCD),is the key point of improvement.This paper compared the design principle of the existing residual current release,focused on the design description and force value amplification principle analysis of this electronic residual current release amplification mechanism,and tested the improvement of residual current performance caused by the electronic residual current release amplification mechanism.It is hoped that this electronic residual current release amplification mechanism can provide a new design idea for domestic manufacturers.

    Reoccurrence of Contact Welding Failure Phenomenon and Failure Mechanism of Miniature Relay
    ZHANG Xu, ZHENG Zhe, LUO Fubiao, ZHOU Zhefeng, REN Wanbin
    2021, 0(10):  52-56.  doi:10.16628/j.cnki.2095-8188.2021.10.009
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    Contact welding failure extremely limits the development trend of miniature relay with long life and high reliability.A special designed test rig is used for the simulation of the electrical performance of contact break and make behavior according to the operation features of miniature relay.The variation in sensitive parameters,including arcing duration,breakaway time,contact resistance and bounce energy,as a function of operation cycles it presented.The precursors of contact welding failure phenomenon are determined.The eroded surface morphologies of failed contacts are obtained.Finally,the contact welding failure mechanism of miniature relay is presented.

    Power Quality
    Research on Flexible Mode Totem-pole Bridgeless PFC Circuit
    LIN Jun
    2021, 0(10):  57-64.  doi:10.16628/j.cnki.2095-8188.2021.10.010
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    In order to reduce conduction loss of the AC-DC converter,a flexible mode totem-pole bridgeless PFC circuit based on totem-pole PFC circuit is proposed.The operating principle,working process and steady state characteristics of the flexible mode PFC circuit are analyzed in detail.Then key parameters are designed and analyzed.A flexible mode totem-pole bridgeless PFC prototype with 90~120 Vrms low input,176~264 Vrms high input and 400 V/600 W output is built and tested.The feasibility and good characteristics of the flexible mode totem-pole bridgeless PFC circuit are verified by the experimental results.

    Study on Effect of Dead Time of Three-Phase Four-Wire System Three-Level APF and Its Suppression Strategy
    ZHAO Weijie, CHANG Wenjing, HUANG Haihong
    2021, 0(10):  65-72.  doi:10.16628/j.cnki.2095-8188.2021.10.011
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    In order to suppress the effects caused by the addition of dead time to the three-phase four-wire NPC-type three-level active power filter (APF),this paper provides a detailed analysis of the dead time effect generation mechanism and the effects of dead time on the output voltage under different switching states and current directions.The dead-time suppression strategy is proposed for the effect brought by the addition of dead-time,and the experimental results verify the effectiveness of the method.

    Design and Implementation of Automatic Debugging and Testing System for Reactive Power Compensation Module Based on Cortex-M3 Single-Chip
    ZHENG Yuejie
    2021, 0(10):  73-77.  doi:10.16628/j.cnki.2095-8188.2021.10.012
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    With the continuous innovation of intelligent reactive power compensation module and an increasing variety of its products,its processes of debugging and testing are also constantly cumbersome.It is almost impossible to complete large-scale production by hand.In order to solve those problems,this paper designs the automatic debugging and detection system of intelligent reactive power compensation module,using Cortex-M3 single chip microcomputer and power acquisition chip to realize the debugging and detection of different types of modules through the switch of relay,so that it can automatically realize the high-precision calibration of modules and the full-featured detection process.The whole system uses self-designed console,large screen LCD,matrix keyboard,modular interface,highly reliable self-protection measures,automatic data recording,which improves the production efficiency,ensures the safety of production,saves a lot of labor costs.

    Electric Vehicle Charging Pile
    Driving Range Prediction of Electric Vehicles Based on Machine Learning
    LI Xiaoyu, CHEN Xuankai, LI Jiaxu, LIN Zihan
    2021, 0(10):  78-82.  doi:10.16628/j.cnki.2095-8188.2021.10.013
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    At the peak of electric vehicle power battery decommissioning,the gradient utilization of batteries has attracted much attention.The mileage of car is an important index to define the aging degree of the battery.To accurately model the range and battery health of the vehicle,the mileage of the electric vehicle is regarded as the research object.On the basis of long short-term memory network,the influence of characteristic parameters including battery system voltage,current,temperature,SOC on the training result of neural network is analysed.Finally,the three-dimensional characteristics of equivalent mileage,discharge cycle power consumption and voltage average value are selected as the input of the neural network model.The best prediction model for the endurance of electric vehicle is obtained.The root mean square error of the prediction result on the test set is 10.81 km.The method is beneficial to electric vehicle energy management and power battery performance degradation evaluation.

    Research on Construction Strategy of Charging Facilities in Scenario with Distributed Generation
    XIAO Yuhua, YIN Yong, JIAO Xize
    2021, 0(10):  83-91.  doi:10.16628/j.cnki.2095-8188.2021.10.014
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    Based on the controllability of electric vehicles in time and mobility in space, it can guide the charging of electric vehicles(EV) when the output of new energy is relatively high, and put forward solutions to the power grid fluctuation caused by intermittent renewable energy. The time energy characteristics of EV charging behavior are analyzed by using the correlation model based on Copula function, and the correlation of charging behavior parameters is verified. The collaborative planning of CSDG and distribution network with distributed generation is studied, and a collaborative planning model of CSDG and distribution network based on two-stage optimization is proposed. On the basis of example analysis, the corresponding reference suggestions for the construction of charging facilities are put forward.

    Application
    Discussion on Low Voltage DC Power Supply System Scheme for Road Lighting
    XU Biao, LIU Yueying, DU Yongbang, ZHONG Anqi
    2021, 0(10):  92-98.  doi:10.16628/j.cnki.2095-8188.2021.10.015
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    With the development of LED street lamps and multi-functional lamp poles,the advantages of lowvoltage DC power supply technology for road lighting have attracted more and more attention.First through the comparison of human AC and DC current effects,the power safety performance of DC power supply is quantitatively analyzed,which can be used as the basis for the safety evaluation of the system scheme.Focusing on the relationship between DC system voltage level,main wiring form,grounding mode and safety performance,the design methods of low voltage DC power supply system for road lighting are studied,and the protection differences of AC and DC systems and their effects on power supply distance and protective appliances are analyzed.Finally,referring to the design examples completed under typical engineering conditions,the application value of road lighting low voltage DC power supply technology in safety,economy and protection characteristics is preliminarily verified.