Table of Content

15 September 2020, Volume 0 Issue 9

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DC Electrical Research

Study on Arc Behavior in Process of Blocking DC Fast Interrupting

PENG Haibo, LI Lingxiao

2020, 0(9):  1-6.  doi:10.16628/j.cnki.2095-8188.2020.09.001

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The development of the arc in the narrow insulation gap is studied by means of the DC interrupting impulse test circuit.Meanwhile,by means of the blocking DC fast interrupting device,the influence of the section perimeter,width,height and effective length of the narrow insulation gap on the arc characteristics is analyzed.Finally,the influence law of the parameters of the insulation narrow gap on the arc characteristics is obtained,which provides ideas and experimental basis for the further development of the barrier DC interrupting method and the design of the improved device.

Simulation and Optimization Design of Eddy Current Repulsion Mechanism with Double Coil for HVDC Relay

ZHOU Baoshi, LIU Xiangjun

2020, 0(9):  7-12.  doi:10.16628/j.cnki.2095-8188.2020.09.002

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The eddy repulsion mechanism with double coil was used to replace the traditional electromagnetic mechanism to improve the breaking speed of the contact,decrease the arc erosion,and reduce the contact bounce during closing at the same time.The optimal design of eddy current repulsion mechanism with double coil will provide the basis for the design of a new kind of HVDC relay.The influence of eddy current repulsion mechanism parameters on dynamic characteristics was analyzed by analytical method.On this basis,Ansoft Maxwell software was used to establish two-dimensional mathematical model of eddy current repulsion mechanism,combining with MATLAB software for the joint simulation.The cuckoo algorithm was introduced into the optimal design to obtain the optimal parameters of eddy current repulsion mechanism,and the optimized eddy current repulsion mechanism has better dynamic performance.

Analysis of Electric-Dynamic Repulsion Force Between Contacts of High Voltage DC Relay

YU Guofei, YUAN Zhonglin, ZHENG Xiang

2020, 0(9):  13-17.  doi:10.16628/j.cnki.2095-8188.2020.09.003

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In order to solve the problem of contact failure caused by too much electric-dynamic repulsion force of high-voltage DC relay under the condition of large short-circuit current,the electro-magnetic field of high-voltage DC relay was analyzed through Ansoft Maxwell.The current density distribution,magnetic intensity distribution and the force of contact,conducting bridge and moving reed under different current were obtained.The influence of moving contact height,contact distance and moving reed structure on the electric repulsion force of moving reed components and parts were analyzed.The theoretical calculation of the electric repulsion force and the finite element electromagnetic field analysis were verified by the short-circuit current experiment.The error between the experimental results and the finite element simulation value is 2.35%.This provides the basis for the optimization design of high-voltage DC relay.

Study on Performance Degradation and Maintenance of Aircraft DC Contactor

YU Chunfeng, ZHANG Xi, WAN Mingming

2020, 0(9):  18-23.  doi:10.16628/j.cnki.2095-8188.2020.09.004

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Contactors are one of the most basic control components in aircraft electrical systems.In recent years,contactor failures of naval aviation aircraft have occurred frequently,and many major flight safety accidents caused by contactor failures have occurred.It is of great significance to conduct contactor performance testing,and study failure laws and maintenance countermeasures,which has a supporting role in improving the reliability of aircraft systems.This paper summarized the differences between the actual use conditions of the contactor on the aircraft and the detection methods of the national military standards,analyzed the use environment of the contactor on the aircraft,designed the test conditions and circuit of the contactor detection,and carried out experiments in the natural environment.Finally,suggestions were made to guide the military in using and maintaining contactors.

Research on Mechanical DC Circuit Breaker Based on Low Voltage Capacitor to Generate Resonant Current

HE Qinglian, FAN Caiyun, LIU Kun

2020, 0(9):  24-29.  doi:10.16628/j.cnki.2095-8188.2020.09.005

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This paper analyzed the characteristics of two topologies of resonant type mechanical DC circuit breakers.A new topology structure of DC circuit breaker with lower cost was proposed.The working principle of the new type DC circuit breaker is analyzed,meanwhile the theoretical calculation basis of the main components of the circuit breaker is also proposed.The design correctness of the main component parameters is verified by simulation.With lower cost and simple control structure,the new DC circuit breaker can be widely applied in the medium voltage DC distribution network field,where the equipment cost needs to be controlled strictly.

Fuzzy Comprehensive Evaluation Method for HVDC Relay Performance

WEI Huihui, LIU Xiangjun

2020, 0(9):  30-35.  doi:10.16628/j.cnki.2095-8188.2020.09.006

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In order to evaluate the performance of HVDC relays,a fuzzy comprehensive evaluation method based on cloud matter-element theory was proposed.Firstly,the evaluation system of the performance index of HVDC relay is established.Due to the randomness of the index parameters and the fuzziness of its rank boundary value,the cloud matter element theory is used to determine the membership degree of the relay performance index,and the improved analytic hierarchy process (AHP) and the CRITIC method are combined to determine the combination weight,then according to the membership degree and the combination weight,the fuzzy comprehensive evaluation model is obtained.Finally,the effectiveness of the method is verified by an example of performance evaluation of HVDC relay.

DC Converting Technology

Design of DC-DC Converter for Fuel Cell Electric Vehicle

ZHANG Weilin, HAN Meng, CHEN Zhao

2020, 0(9):  36-39.  doi:10.16628/j.cnki.2095-8188.2020.09.007

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Fuel cells used in electric vehicles are equipped the characteristics of wide range of output voltage,low output voltage and large output current.The high gain boost converter to supply power to lower level equipment is needed.In order to reduce the volume and electric stress of the converter,a three-level Boost converter for electric vehicles was designed.By analyzing the working principle of three-level Boost converter,the mathematical model of controlling to output was established by using state space averaging method.According to the solution structure of model,the corresponding PI compensation network was designed in control circuit.The performance of PI compensation network in control system was analyzed.The accuracy and feasibility of the compensation network are verified by experiments.The established model also provides corresponding theoretical basis for analysis of other circuits,equipped with certain popularization value.

Design of a Digital DC-DC Power Supply Based on Composite Topology

SONG Haoyi, LI Yong, LIAO Jianjun

2020, 0(9):  40-45.  doi:10.16628/j.cnki.2095-8188.2020.09.008

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This paper proposed a composite topology structure combining Buck and the full bridge,which can reduce the pressure of the switch tube and realize the topology change function when necessary.Then,according to the characteristics of digital controller,a double loop control method is adopted,in which voltage loop is the outer loop and current loop is the inner loop.The complex topology of Buck and full bridge is modeled,and the double loop control is added to the system for analysis and modeling.In order to verify the practicability of the complex topology and control method,MATLAB is used to analyze the designed topology and control in frequency and time domain.At the same time,the 300 W digital power supply is designed by using compound topology and double loop control method.Finally,the effectiveness and practicability of the compound topology and double loop control are proved.

Development of Energy-Fed DC Electronic Load Based on H-Bridge Boost Circuit

JIN Chunyang, RUAN Xiangyong, SONG Guangming, HUANG Haihong

2020, 0(9):  46-49.  doi:10.16628/j.cnki.2095-8188.2020.09.009

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For the low-voltage,high-current DC power supply aging test requiring discharge load,a feed-type DC electronic load is developed.The pre-stage DC-DC converter uses the H-bridge Boost circuit as the main circuit topology to implement discharge load characteristics and achieve boost and maintain the stability of output terminal voltage.The post-stage DC-AC converter adopts TMS320F2812 as the main control chip and current-loop as control strategy and applies grid voltage feed-forward control,so that this system can approach unity power factor to feed energy back to the grid under a set power,and the total harmonic distortion of the grid-connected current does not exceed 5%,which meets the requirements for grid-connection.

Control Strategy of Virtual Diesel Generator Set for Shipboard Inverter

ZHAN Hangxing, LIU Luhui, XIAO Xiongbo, LIN Yunfeng

2020, 0(9):  50-56.  doi:10.16628/j.cnki.2095-8188.2020.09.010

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Aiming at the problems of excessive overshoot and long steady-state adjustment time during loading and unloading,and the need to switch control strategies during grid connection and disconnection when the inverter and diesel generator (DG) sets are operated in parallel.A simplified virtual diesel generator control strategy is proposed.In this paper,a mathematical model of the control strategy of a virtual diesel generator set (VDGS) is established,and the influence of control system parameters on system stability is analyzed.Based on MATLAB/Simulink modeling simulation,the results show that the proposed control strategy can significantly reduce the overshoot during loading and unloading,reduce the adjustment time,and there is no need to switch the control mode during grid connection and disconnection.

Analysis of Voltage Ripple on DC Side of Shunt Active Power Filter and Improvement of Voltage Loop Design

WANG Yuhang, WANG Haixin, HUANG Haihong

2020, 0(9):  57-62.  doi:10.16628/j.cnki.2095-8188.2020.09.011

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When the shunt active power filter (SAPF) compensates the harmonic current,the DC capacitor voltage will have corresponding pulsation,which will have a bad effect on the compensation effect.Based on three-phase three wire system and three-phase four wire system,the causes of capacitor voltage ripple are analyzed theoretically,and a notch filter with specific frequency is put into the voltage loop.The simulation and experiment show that the improved voltage loop can reduce the influence of capacitor voltage ripple.

Research of Embedded Simulation Platform for DC-DC Power Converters

FAN Xiao, PAN Benren, HU Sideng, QU Shaoxing

2020, 0(9):  63-67.  doi:10.16628/j.cnki.2095-8188.2020.09.012

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This article proposes a cross-hardware solution about the simulation of power electronics model on general embedded systems by discussing digitization approaches such as power electronic system modeling methods and discrete numerical integration methods.It also implements an embedded system simulation platform on an STM32 chip and verifies its reliability by comparing it with Simulink simulation results on multiple power electronic circuits.

Detection & Experiment

Research on Control Cabinet Shaking Table Test for UHVDC Transmission Project

CHEN Xiangdong, PAN Guohong, LU Xiang, HUANG Xionghui, ZHUO Ran

2020, 0(9):  68-71.  doi:10.16628/j.cnki.2095-8188.2020.09.013

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As high voltage level,large transmission capacity and sophisticated control strategy in UHV converter station,stability of control cabinet should be significant for safe operation of power grid.4 live cabinet for UHV transmission project were tested on shaking table with the input of artificial seismic wave at 9 degree intensity to test their anti-seismic performance.The test results show that the objects satisfied the anti-seismic requirements without structural and electrical damage in the test.

Research and Analysis of Two-Phase Arc Fault Test in 12 kV Switchgear

HU Dingyin, YU Wenbo, JIN Qingbin, PENG Jianfei, ZHE Yongxiang, LI Yang, FENG Lun, HE Bing

2020, 0(9):  72-78.  doi:10.16628/j.cnki.2095-8188.2020.09.014

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According to IEC 62271-200 or GB/T 3906 standard,two-phase fault will develop into three-phase fault in 12 kV switchgear when conducting two-phase type test of internal arc fault,which mostly occurs in the initial stage and middle stage of flow passage.This paper studies and analyzes this situation through typical test cases,and further analyzes the development of two-phase fault into three-phase fault through simulation.The analysis shows that the current will increase when two-phase fault develops into three-phase fault,and the voltage phase of the phase corresponding to the starting point of the third-phase current ignited is uncertain,which directly affects the maximum current peak of the phase.The results show that the reason of insulation failure can be analyzed by the development of two-phase fault into three-phase fault,which provides a reference for the improvement of the performance of the switchgear.

Distribution System Technology

Integrated Protection Method of Intelligent Anti Harmonic Voltage Transformer Based on Internet of Things

GUO Min, HE Guoxin, SHI Tongheng, LIANG Guangsheng, JIN Qingren, YAO Zhiyang, CHEN Weidong

2020, 0(9):  79-85.  doi:10.16628/j.cnki.2095-8188.2020.09.015

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In order to solve the problems of primary winding burning,high voltage fuse fusing and too large third harmonic voltage containing rate of electromagnetic voltage transformer in the distribution network of non grounded neutral system,this paper analyzed the mechanism of electromagnetic voltage transformer frequent damage,compared the advantages and disadvantages of various methods of electromagnetic voltage transformer protection,put forward an intelligent anti harmonic electromagnetic voltage transformer comprehensive protection method based on the Internet of things,and designed the corresponding devices,developed the corresponding Internet of things app,and put it into the field application.This method can correctly and reliably protect electromagnetic voltage transformer when the system and transformer are abnormal.At the same time,when the system is in normal operation,the vacuum switch can inhibit the voltage deviation of the measurement opening of the system,not affect the measurement and protection of the system,and improve the power quality characteristics of the signal.The feasibility and correctness of the proposed method were verified by the monitoring data.

Intelligent Monitoring System for Rural Low Voltage Distribution Transformer Station Area Based on Internet of Things

WANG Fei, TIAN Le

2020, 0(9):  86-89.  doi:10.16628/j.cnki.2095-8188.2020.09.016

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The rural power grid transmission line leakage protection device has a low insurance rate,and the traditional leakage protector cannot detect the location of the leakage after the tripping action,causing the rural power grid operation and maintenance personnel to fail to perform timely repairs.This article developed an intelligent monitoring system for rural low voltage distribution transformer station areas based on the Internet of Things.It uploads the monitoring results of various electrical parameters such as field leakage,neutral line current,and transformer temperature to the power supply monitoring system.The system realizes the real-time monitoring of the power consumption status of each transformer area,and finally provides a reliable basis for solving the problem of low voltage line leakage point,making the fault judgment of the operation and maintenance personnel accurate to the user,and improving the power supply reliability and user satisfaction.

Net Load Forecasting of Distribution Network Based on Bayesian Network

LI Xiaowei, TAO Yigang, GU Jie, LIU Shuqi, LI Min, CHEN Chu, LI Rongyao

2020, 0(9):  90-98.  doi:10.16628/j.cnki.2095-8188.2020.09.017

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Increasing penetration of distributed renewable energy poses challenges to the safe and stable operation of the distribution network,which makes load forecasting problem considering renewable energy access scenario become the research focus.This paper analyzed the coupling and interaction between the user side load and the power generated by renewable energy and proposed a direct forecasting method of net load of distribution network based on Bayesian network.Firstly,the Bayesian network structure is established according to the causal relationship between each influencing factor and net load of distribution network,then the network parameters are learned with historical data,and finally the Bayesian network for net load prediction of distribution network is generated.The model is tested with the actual data of distribution network in a foreign country.Compared with the prediction models such as support vector machine (SVM),the prediction error of the model proposed in this paper is small,which can effectively improve the prediction accuracy of net load of distribution network.

High Impedance Fault Ide.pngication in Distribution Network Based on One-Dimensional Convolution Neural Network

LIU Bingnan, HUANG Yiping, FANG Guobiao

2020, 0(9):  99-103.  doi:10.16628/j.cnki.2095-8188.2020.09.018

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The power distribution network is directly connected with the user.Its stability is closely related to the power system’s ability to deliver power to the user side.The operation environment of distribution network is complex and extensive,and high impedance fault (HIF) occurs when the operation line falls into contact with trees,grass and other conditions.At this point,the impedance of the fault point reaches several hundred or even several thousand ohms,and the amplitude of voltage and current changes weakly,so the fault is difficult to be detected.If the fault can’t be eliminated in time,the intermittent arc at fault point will cause immeasurable damage.In this paper,the Hilbert-Huang Transform (HHT) band-pass filter is used to extract the feature quantity,to form the time-frequency energy matrix,one-dimensional convolutional neural network (1D-CNN) is used to construct classifier for fault classification.The simulation model is verified and the adaptability is analyzed.The results show that the algorithm has high accuracy and good adaptability.