Table of Content

15 June 2020, Volume 0 Issue 6

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Research & Analysis

Experimental Research on Short Circuit Breaking of Moulded Case Circuit Breaker

YUAN Xuebing, ZHAO Hu, CAI Mingyang

2020, 0(6):  1-4.  doi:10.16628/j.cnki.2095-8188.2020.06.001

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Arc reignition is the most common phenomenon of short circuit interruption process,and it has direct impact on short circuit breaking capacity.Because arc reignition is affected by various design parameters,it is difficult to be analyzed quantificationally.In this paper,a metal splitter voltage measurement equipment system was used to analyze arc reignition and post-arc current.Thermal breakdown and electrical breakdown are two reignition phenomena of short circuit breaking process,this paper presented the physical process analysis with these measured data for both two reignition phenomena.Finally,the improvement advices upon arc chamber system were given.

Experimental Investigation of Contact Bounce Phenomena Occurred in Electromagnetic Relay

FANG Yaqi, REN Wanbin

2020, 0(6):  5-9.  doi:10.16628/j.cnki.2095-8188.2020.06.002

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The behavior of contact closure bounce is directly related to the dynamic response characteristics and electrical life of the electromagnetic relay.In this article,the physical model of the contact closure bounce behavior is introduced firstly.Secondly,the effects of magnetic gap,contact gap and load voltage on bounce duration,bounce height and bounce times are investigated experimentally.The conclusions can provide reference for the optimization design of electromagnetic relay and the failure analysis of dynamic contact welding.

Study on Excitation Power Circulation Suppression and DC Voltage Limitation of DC Pulse Generator Set

TAO Hongliang, WANG Haixin, HUANG Haihong

2020, 0(6):  10-14.  doi:10.16628/j.cnki.2095-8188.2020.06.003

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In order to avoid the load impact on the power grid,the DC pulse generator sets are widely used in the fusion experimental equipment.However,the traditional open-loop excitation voltage control method can not solve the circulation problem when the generator sets operate in parallel.Aiming at this problem,based on the theoretical analysis of circulation suppression measures,this paper put forward a kind of armature current closed-loop feedback control of excitation power supply system,and starting from the engineering actual situation,expounded the DC side capacitor voltage pump up problems,and put forward the solution of natural continued flow capacitance bypass,eliminating the dead band time adverse impacts on the natural stream.The simulation and experiment prove the rationality of the design of the excitation power supply system.

Analysis of Carbon-Copper Material Transfer Characteristics Under Pantograph-Catenary Arc

ZHANG Dong, LU Chao, MU Tingyou, SHE Pengpeng

2020, 0(6):  15-19.  doi:10.16628/j.cnki.2095-8188.2020.06.004

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Under the arc erosion,material transfer occurs between pantograph and catenary,which aggravates the loss of pantograph and catenary materials,and seriously affects the flow quality of the pantograph-catenary system.It not only limits the further improvement of the train running speed,but even endangers the safety of train operation.In this paper,the arc ablation experiment under different polarities was carried out based on the arc ablation experimental platform.The following conclusions can be drawn by combining the motion characteristics of the arc,the surface morphology of the electrode,and the ablative quantity.Under the arc erosion,the material transfer phenomenon of the anode is more obvious.When copper is used as the anode,as the current increases,the molten copper on the surface of the copper electrode drops onto the pantograph strip due to its own gravity exceeding the surface binding force,and the copper electrode undergoes obvious material transfer behavior.When carbon is used as the anode,carbon accumulates on the surface of the copper electrode to form carbon bumps,and the carbon electrode undergoes obvious material transfer behavior.

Electrical Design & Discussion

Analysis of Non-Action of Shunt Release of MCCB at Low Temperature

ZHANG Yan, WANG Yang

2020, 0(6):  20-24.  doi:10.16628/j.cnki.2095-8188.2020.06.005

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This paper analyzed the problem that the shunt release of moulded case circuit break(MCCB) does not operate at low temperature.The solution to the problem of low temperature non-action of auxiliary suction shunt release and self suction shunt release was proposed respectively.The analysis shows that the problem is related to the way of applying lubricating grease,as well as the rolling and polishing process.

Temperature Rise Prediction and Simulation Analysis of Miniature Circuit Breaker

YANG Wenqiang, ZHANG Penghe, ZHANG Baoliang

2020, 0(6):  25-29.  doi:10.16628/j.cnki.2095-8188.2020.06.006

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The temperature rise formula of miniature circuit breaker terminal was derived from the thermal balance equation.The stable temperature rise coefficient and temperature rise time constant coefficient of the formula were calculated by the least-square method.An algorithm for predicting stable temperature rise from sampling temperature of the first 40 minutes was compiled,the temperature and time data of many samples at 150%T_N,120%T_N,100%T_N,and 70%T_N were taken to calculate the predicted temperature rise and the temperature rise time constant.Next,the temperature rise and time fitting curve was drawn,which fits well with the actual temperature rise and time curve.It verifies the feasibility of the temperature rise prediction algorithm.In view of the circuit breaker thermal test,only the temperature rise of the terminal and the shell can be obtained,and the temperature rise of the contacts inside the breaker,cannot be measured directly.This paper also uses finite element simulation to explore the temperature distribution near the contacts,supplementing the temperature rise measurement of the circuit breaker.

Factors Affecting Performance Characteristics of Bimetallic Strip Products and Parameter Design

HU Jianguo, WANG Jingkai, HUANG Heping

2020, 0(6):  30-35.  doi:10.16628/j.cnki.2095-8188.2020.06.007

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To make the performance characteristics of bimetallic strip products more stable,a mathematical model of the output characteristic value y of the bimetallic product was established considering various factors and taking the sum of the idle stroke margin under the stable current of the product and the stroke margin under the operating current as the design margin; the parameter design method is used to analyze the influencing factors in the mathematical model of the operating characteristics of the bimetallic product.The results show that:the larger the main double-specific bending value,the smaller the auxiliary double-specific bending value,the smaller the out-of-synchronization error generated after verification,the better the output of the operating characteristics.The mathematical model of the operating characteristics value y can provide an effective direction and basis for the design optimization and process improvement of the stability of operating characteristics of the motor starter.

Improvement Design of Tripping Velocity for Miniature Circuit Breaker

SHEN Xian, WANG Bingqing

2020, 0(6):  36-40.  doi:10.16628/j.cnki.2095-8188.2020.06.008

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The tripping velocity of miniature circuit breaker has a great effect on the short circuit breaking capacity;the quicker velocity,the better current limiting ability,also the better short circuit breaking performance.How to improve the tripping velocity based on the small changes of existing mechanism,is always a difficult point.The tripping plunger to trip is used,then go on pushing the moving contact,by which it improves the tirpping velocity of miniature circuit breaker.This method is verified by motion simulation,high-speed photography and short circuit breaking tests.

Detection & Experiment

Research and Design of An Intelligent Impedance Controller

ZHANG Zongqin, YANG Shijiang

2020, 0(6):  41-45.  doi:10.16628/j.cnki.2095-8188.2020.06.009

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In view of the shortcomings of the impedance switching mode in the current low voltage circuit breaker short-circuit testing,electrical-life testing and so on,an intelligent impedance controller was proposed.Firstly,this paper analyzes the function of the intelligent impedance controller based on the actual use of the test equipment,and then discusses in detail how to carry out the intelligent control,including the calculation of the impedance by using the test parameters and the realization of the impedance automatic switching by using the look-up table method and IO correlation.Then,according to the functional decomposition of the controller,the hardware and the corresponding software are designed on the hardware platform.The intelligent impedance controller designed in this paper is tested and verified in the MCB electrical-life equipment,it realizes the function of impedance automatic switching,and overcomes the shortcomings of traditional impedance switching.

Low Voltage Cable Thermal Stability Check for Circuit Breaker Protection

WANG Congke, ZHANG Shu

2020, 0(6):  46-52.  doi:10.16628/j.cnki.2095-8188.2020.06.010

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Through the specific distribution system,the effects of different types of circuit breakers on the thermal stability of low voltage cables are calculated in detail.According to the normal frame level of the circuit breaker rated current,the cable section of the distribution circuit is 6 mm² or above,which can meet the requirements of thermal stability.It is proposed that the thermal stability of the cable should not be checked unless it is very close to the distribution cabinet of the substation or the cable section of the distribution circuit is very small.

Cable Accessory Partial Discharge Detection System Based on Multi-Sensor Fusion Technology

LI Fangli, QIAN Shuaiwei, MAO Zhengyu, WANG Pengpeng, DU Xuan

2020, 0(6):  53-60.  doi:10.16628/j.cnki.2095-8188.2020.06.011

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A partial discharge(PD) detection system of cable accessories based on multi-sensor fusion technology was designed and implemented.Based on a high-speed acquisition card data acquisition platform,the detection system enables on-line detection of cable insulation conditions through the combination of ultra high frequency(UHF) sensors,ultrasonic(acoustic emission,AE) sensors and high frequency current transducers(HFCT).A PD signal denoising method was proposed,which can distinguish the pure noise signal part of the PD detection signal from the part containing the PD pulse signal,and it is not limited by the number of PD pulses and the position of the pulse.Finally,six defect models were constructed,and their partial discharge characteristics were studied separately.The database was established to provide a reference for the study of partial cable discharge.

Research on Detection Method of AC Contactor Holding Vibration Based on Support Vector Machine

QING Qimao, ZHOU Taiwu, LI Wenli

2020, 0(6):  61-64.  doi:10.16628/j.cnki.2095-8188.2020.06.012

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The support vector machine(SVM) can be used for training and classification in the condition of small samples.This paper presented a detection method of AC contactor holding vibration based on SVM.Firstly,a small number of vibration time domain signals from the base plate of AC contactor which is not qualified for vibration test are extracted,then a virtual vibration test classifier is established by training the sample data and using support vector classifier(SVC).The experimental results show that the method has a good classification and recognition ability for the samples of the follow-up contactor.

Distribution System Technology

Analysis of Single-Phase Grounding Fault in Pre-AC Protection Zone of Distribution Network Based on MMC

XIAO Xiaobing, FU Yu, ZHANG Ruifeng, LONG Qiufeng, ZHENG Youzhuo, LIU Anjiang, ZHANG Yang

2020, 0(6):  65-70.  doi:10.16628/j.cnki.2095-8188.2020.06.013

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The modular multilevel converter(MMC) shows good adaptability in distribution network with its unique structural advantages and has been applied more and more widely.In this paper,the distribution network modeling process based on MMC,fault simulation,fault feature analysis and protection configuration scheme were studied,including the topological structure of distribution equipment and the construction of the simulation model.Based on the result of failure characteristics and,the main protection and backup protection scheme was designed,so that to more effectively protect the power distribution network.

Distribution Network Low Voltage Prediction Method Based on Support Vector Machine

TAO Li, GUO Yingxuan, XIA Jun, XIONG Fangxian, LIANG Yuping

2020, 0(6):  71-75.  doi:10.16628/j.cnki.2095-8188.2020.06.014

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Aiming at the lack of direct functional relationship between voltage-related parameters in the distribution network,it is difficult to scientifically carry out low voltage prediction.This paper proposed a low voltage prediction method based on support vector machine.The method uses a large number of distribution network voltage and voltage-related data as the training sample set,and uses the support vector machine method to find the optimal function relation in many samples,and forms a decision function to carry out the voltage prediction at the end of the low voltage side of the distribution network.The actual monitoring voltage of the distribution network in a certain area is compared with the predicted voltage of the support vector machine.The error between the predicted value of the parameter and the actual monitored value is small,which verifies the validity and feasibility of the low voltage prediction method based on vector machine in the distribution network.

Design of Comprehensive On-line Monitoring System Based on Grounding Current of Tower

LI Haifeng, WANG Weiwen, GUO Zhigang, HAN Jinfu, YANG Wei

2020, 0(6):  76-81.  doi:10.16628/j.cnki.2095-8188.2020.06.015

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With the transformation of the energy structure,the development of new energy has directly promoted the construction of long-distance high-voltage transmission grids,which has further expanded the construction scale.Under the above background,pole and tower faults are becoming more frequent,and the direct or indirect economic losses caused by them are also getting higher and higher.Based on this,this article introduces a comprehensive on-line monitoring system for transmission towers,which effectively and accurately grasps the operating status of transmission lines in the pipeline area,uses grounding current to locate and classify the faults of towers and transmission lines,which can prevent major power outages.

Multi-Voltage Level Reliability and Economy Coordinated Assessment in Power System

CHEN Qi, XU Pengcheng, SHI Daogui, ZHANG Hao

2020, 0(6):  82-88.  doi:10.16628/j.cnki.2095-8188.2020.06.016

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This paper presented a method of multi-voltage level coordinated expansion planning in distribution network.Considering the effect of transmission system and the main electric connection schemes of substation,the reliability parameter of transmission is equivalent to the distribution network power node for multi-voltage level reliability calculation.Based on life cycle cost(LCC),the assessment of reliability and economy is carried out,which selects the unit cost of average service availability index(ASAI) increment as the objection function.Finally,the proposed method was well applied to different improved planning,and the optimum conditions are obtained which serves the long-term interests of power grid.

Electric Vehicle Charging Pile Technology

Evaluation of Electric Vehicle Charging Network Operation Based on AHP-TOPSIS Method

TANG Xiaodong, JU Chen, GAO Xiao

2020, 0(6):  89-95.  doi:10.16628/j.cnki.2095-8188.2020.06.017

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A comprehensive evaluation method based on AHP-TOPSIS was proposed to overcome the shortcomings of deficiency of indicator value processing and insufficient industry applicability for the current charging network operation management and evaluation and rating methods.In the evaluation method,an evaluation index system of operation was established from four aspects:public service level,customer service quality,site management level and impact on the environment.After the assimilation processing of the indexes according to their different characteristics,cosine distance between sites to be evaluated and the positive/negative ideal situation was calculated combined with the weight obtained by AHP.A numerical analysis shows the rationality and feasibility of the method,which can effectively quantify the operation of charging network and provide technical support for industry supervision.

Tabu Search Charging Positioning Algorithm for Random Driving Electric Vehicles

HE Ruihui, ZHEN Zhen, XING Tao, SHI Jinyong

2020, 0(6):  96-102.  doi:10.16628/j.cnki.2095-8188.2020.06.018

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Aiming at the randomness of the driving range of electric vehicles and the charging station location problem caused by different charging requirements,the problem of deterministic flow charging positioning is analyzed,and the expected flow charging positioning model of electric vehicles is established,and the random driving problem of electric vehicles in this model is solved.The tabu search algorithm is used to perform heuristic solution analysis to obtain the best positioning solution.The experimental data shows that the tabu search algorithm can always provide high-quality solutions in a short calculation time,providing theoretical support for the planning and positioning of charging stations.