Table of Content

15 January 2020, Volume 0 Issue 1

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Overview

Energy Storage Technology and Its Application in Global Energy Internet

LI Jianlin, MENG Gaojun, GE Le, ZHOU Jinghua, SHI Wenhui, ZHANG Zhankui

2020, 0(1):  1-8.  doi:10.16628/j.cnki.2095-8188.2020.01.001

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The construction of energy Internet is an important way to realize the rational allocation of energy and the sustainable development of resources,and energy storage technology is a key link in the construction of energy Internet.In view of the energy storage technology and its application in the global energy Internet,this paper first introduced the types and characteristics of the energy storage technology,and expounded the energy storage technology requirements of each ring of the energy Internet and the current situation of the global energy storage development.With the development of energy storage market in typical countries and regions,this paper analyzed the contribution and enlightenment of its policies to the development of local energy storage industry.Then the configuration plan of energy storage technology was given according to the source,network,load and other links of the global energy Internet.Finally,combined with the energy development demand and policy-oriented factors of typical areas at present,this paper forecasts and looks forward to the development of energy storage industry in the future.

Research & Analysis

Research on Noise Processing and Fast Detection Method of Short Circuit Fault in Low Voltage System

YAN Qichen, MIAO Xiren, ZHUANG Shengbin

2020, 0(1):  9-16.  doi:10.16628/j.cnki.2095-8188.2020.01.002

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In order to effectively utilize the fault characteristic of current surge after the occurrence of a short-circuit fault to achieve accurate identification of short-circuit faults,an effective filter must be designed to retain the fault feature while weakening the influence of noise.In this paper,a combined average generalized morphological filter was proposed to study its filtering effect on impulse noise,high frequency noise and Gauss white noise,as well as the improvement of the accuracy of the wavelet decomposition method.It is concluded that the combined average generalized morphological filter can effectively suppress the above three kinds of noise and significantly improve the accuracy of the detection algorithm.By comparing the combined average generalized morphological filter with the median filter and mean filter,the conclusion is drawn that the combined average generalized morphological filter has better lifting effect.The experiments show that the combination of combined average generalized morphological filter and wavelet decomposition method can make the lifting coefficient reach 11.21,the detection time costs 0.35 ms,and the filter delay only takes 0.11 ms.This combination has the real-time and rapid characteristics of fast detection of short-circuit faults,and is suitable for fast detection and fault protection applications of short-circuit faults in lowvoltage distribution systems.

Simulation Research of Arc Characteristics Under Lowering Pantograph in Railway Station

GAO Guoqiang, LI Chengkun, WEI Wenfu, Yang Zefeng, CHEN shaokun, DUAN Xuwei, ZHU Yuehui, LIAO Shiming, TAO Guidong

2020, 0(1):  17-23.  doi:10.16628/j.cnki.2095-8188.2020.01.003

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Lowering pantograph operation would be taken when locomotive pulls into railway station.Arc caused by lowering pantograph operation would severely ablate pantograph catenary materials due to the arc root stagnating at the surface of pantograph catenary electrodes.The arc simulation model is established based on the magnetohydrodynamics (MHD) to study the effects of lowering pantograph speed and natural wind velocity on the characteristics of arc.The results show that the lowering pantograph speed and natural wind velocity have a relatively weak impact on the temperature distribution of arc.As lowering pantograph speed and natural wind velocity rise,both arc length and arc voltage increase gradually,the derivative of arc voltage with respect to time dU/dt presents an approximately linear increase,while the derivative of arc voltage with respect to arc length dU/ds keeps constant.The natural wind velocity has a larger impact on arc length and arc voltage than the lowering pantograph speed.In order to reduce pantograph catenary material erosion,arc duration could be shorten by increasing lowering pantograph speed and installing arc blow equipment.

A Review of Low Voltage AC Series Arc Fault Detection

YU Qiongfang, HU Yaqian, YANG Yi

2020, 0(1):  24-30.  doi:10.16628/j.cnki.2095-8188.2020.01.004

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In low voltage AC power supply and distribution lines,arc fault is the main cause of electrical fires,which brings serious safety hazards to the operation of power systems.In order to protect the electrical safety,the arc fault types are described,detection difficulties and current waveform characteristics of series arc fault in the residential power supply and distribution lines are analyzed.The advantages and disadvantages of detection methods based on arc mathematical model,arc physics feature and arc current voltage waveform are discussed.Several arc fault detection patents are exemplified and their shortcomings are analyzed.The future development direction of the series arc fault detection method is prospected.An high-precision identification algorithm based on multi-feature information fusion,deep learning and adaptive protection need to be further researched.

Research on Intelligent Distributed FA Fault Self-Healing Based on GOOSE

CAO Yundong, LIU Rui, HOU Chunguang

2020, 0(1):  31-35.  doi:10.16628/j.cnki.2095-8188.2020.01.005

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As the distributed generation and micro-grids continue to access the distribution network,the traditional feeder-type feeder automation (FA) and centralized FA have problems such as long failure recovery time and poor flexibility,which reduces power supply reliability.In order to solve the above problems,an intelligent distributed FA fault self-healing implementation scheme based on GOOSE service was studied.Based on the analysis of the whole self-healing process of fault location,fault isolation and power restoration in non-faulty areas,according to the requirements of intelligent distributed technology for communication,the information interaction process based on GOOSE service was given.According to the fault self-healing process,the engineering configuration of the system was studied.The information modeling of the intelligent terminal was applied to the specific distribution network structure,and the effectiveness of the scheme is verified.

Electrical Design & Discussion

Summary of Research on Dual-Power Switching Power Supply Access Devices

JIAN Meijia, LOU Weiguo, MA Xuewei, BAI Huadong

2020, 0(1):  36-39.  doi:10.16628/j.cnki.2095-8188.2020.01.006

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This paper presented a new solution of connecting mobile power generation vehicle with low voltage distribution equipment bus.An emergency power supply of power generation vehicle is connected to low voltage distribution cabinet quickly and efficiently through a dual-power switching power supply access device to realize the non-stop operation of distribution network.The structure and working principle of the device were elaborated and summarized in detail,and the effects and application fields were evaluated.

Fast Algorithm of Contactor Performance Based on Radial Basis Function Neural Network

XIAO Bin, LIU Yang, ZHAI Guofu

2020, 0(1):  40-45.  doi:10.16628/j.cnki.2095-8188.2020.01.007

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With the rapid development of new energy systems and the significant increase in power consumption,users put forward new requirements for the performance and reliability of contactors.The optimal design of contactors becomes a hot issue.Restricted by the low efficiency for computation of contactor performance,intelligent optimization algorithms with strong global search ability can’t be well applied in contactor optimization design.That limits the development of contactor optimization design so it is necessary to study the fast calculation algorithms of contactor performance.In this paper,an approximate model for contactors was proposed,which is based on radial basis function (RBF) neural network.The parameters of the RBF neural network are optimized by RPCL and PSO to ensure the accuracy of the model.Taking the static and dynamic characteristics of a high-power contactor as an example,it takes 40 seconds for an approximate model to calculate the dynamic characteristics,while nearly one day for the commonly used finite element method.The error of the approximate model is less than 5%.In general,the model greatly improves the efficiency of computation of the performance of contactors and lays the foundation of optimal design of contactors.

Electrothermal Coupling Analysis and Experimental Verification of Silver Tin Plating Arc Trigger

FU Xue, QI Liansuo, ZHUANG Jinwu, YAN Ling, LU Wei

2020, 0(1):  46-50.  doi:10.16628/j.cnki.2095-8188.2020.01.008

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The arc flip-flop with rated current of 500 A is taken as the research object.The mathematical modeling and analysis were carried out for the tin layer plated on the flip-flop melt with a thickness of 5μm.The simulation model of arc flip-flop was established by using the electrothermal coupling module of COMSOL platform.The simulation results show that the per-arc time of the flip-flop under 4 kA overload current is 7.5 seconds,and then the arc trigger test sample with tin plating thickness of 5 μm was made.The pre-arc characteristic test was carried out.The test results are basically consistent with the simulation results.On this basis,the pre-arc time under different tin plating thickness was studied.The simulation results show that the thinner the tin plating thickness is,the shorter the pre-arc time of the trigger is.

DC Technology

Study on Reliability Evaluation of Key Equipment in AC/DC Distribution Network

DING Jiming, DUAN Haowei

2020, 0(1):  51-57.  doi:10.16628/j.cnki.2095-8188.2020.01.009

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In order to deal with the contradiction of limited station corridor and high load density of urban power grid,the development of AC/DC distribution network is an important development trend to solve the problem.However,the technology of key equipment such as medium voltage DC circuit breaker and DC transformer is not mature and the construction standard is not perfect,so it is necessary to evaluate and analyze the reliability level of equipment and distribution system.In this paper,by analyzing the factors that affect the reliability of AC/DC distribution network,the reliability evaluation model of key equipment in AC/DC distribution network was established and the reliability parameters were calculated.The reliability evaluation method of distribution system is based on the minimum cut set method.According to the evaluation results,compared with the traditional AC distribution network,the two-way connection characteristic of flexible AC and DC distribution network further improves the overall power supply reliability of the system on the basis of realizing the whole system’s flexible control.

Modeling and Simulation Analysis of Multi-Terminal Flexible AC/DC Hybrid Distribution Network

TU Xiaotao, GAO Shilong, CHEN Rui, HU Yongjie, HE Qinglian

2020, 0(1):  58-63.  doi:10.16628/j.cnki.2095-8188.2020.01.010

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A multi-terminal flexible hybrid DC distribution network constructed with area AC/DC as basic unit has advantages such as convenient access to a variety of power suppy,losd and storage energy device,which has become the development direction of current distribution network.Based on VSC converter of half-bridge sub-module structure,this paper established a multi-terminal DC distribution network model including DC circuit breaker and power electronic transformer,analyzed the system’s operation characteristics from the start,steady-state and fault aspects respectively,which verifies the reliability of system’s control strategy.

Research on Hybrid Power Electronic Transformer Based on Modular Multi-level Converter and Its Control Strategy

LIU Mengxuan, FAN Dongqi, JIN Cheng

2020, 0(1):  64-70.  doi:10.16628/j.cnki.2095-8188.2020.01.011

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This paper presented a hybrid power electronic transformer based on modular multi-level converter and its control method.The basic control strategy of power electronic transformer proposed in this paper adopts voltage and current double-loop control.The outer voltage loop adopts PR controller,and the inner current loop adopts P controller.In addition,a low-frequency ripple control method is added to enable the device to operate normally under the output low frequency condition,which overcomes the defect that the device cannot operate normally under the low frequency condition by traditional control method.When a voltage drop or sudden rise occurs in the power grid,the voltage compensation control proposed in this paper can be used to compensate the voltage and improve the power quality of the grid.The feasibility of the proposed multi-functional hybrid power electronic transformer and its control strategy is verified by the simulation experiments.

A Modular Multi-Level Power Electronic Transformer and Its Control Strategy

ZHOU Bin, XU Jingnan, GUO Xuan

2020, 0(1):  71-77.  doi:10.16628/j.cnki.2095-8188.2020.01.012

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This paper presented a control strategy for a modular multi-level power electronic transformer (MMC-PET).Firstly,the MMC-PET topology is analyzed and its mathematical models of input and output stages are established.Secondly,a feedback linearization and variable structure controller is designed to control the input and output stages of MMC-PET,aiming at the disadvantages of the traditional cross decoupling control strategy based on PI control,such as poor robustness and complex control system.Finally,the simulation model of MMC-PET system is established and verified.The simulation results show that the control strategy of input and output stages of MMC-PET based on feedback linearization and variable structure controller can effectively achieve the control purpose,and has the characteristics of fast decoupling speed,strong decoupling and robustness.

Generation Automation

Two-Stage Optimal Dispatching of Active Distribution Network with Two Layers of Source-Network-Load

LI Jiyu, JIANG Xiubo, LI Gongxin, FAN Ying

2020, 0(1):  78-85.  doi:10.16628/j.cnki.2095-8188.2020.01.013

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In order to fully absorb apoplexy and optical DG in active distribution network (ADN) and promote the efficient utilization of controllable resources such as energy storage devices and flexible loads,a two-layer two-stage optimal dispatch based on source-network-load was proposed.In the previous two-tier optimal dispatching stage,the upper level is active power optimal dispatching,and the lower level is reactive power optimal dispatching with DG as reactive power output source,which is solved by binary chaotic bat algorithm.In the real-time dispatching stage,ultra-short-term prediction based on improved data stream on-line segmentation is used to revise the previous dispatching scheme in real time.Finally,a modified IEEE-33 bus system is used as an example to verify the effectiveness of the scheduling scheme.

Design of Positioning Terminal Software Based on Android Platform

ZHAO Yuan, LI Zhe, LIN Yanqing, PEI Junyi, FU Yida

2020, 0(1):  86-89.  doi:10.16628/j.cnki.2095-8188.2020.01.014

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Aiming at the problem of lack of intelligent management,this paper proposed to locate the automation equipment by using base station positioning and GPS positioning,designed an on-site management software based on Android.By automatically locating the current location information and the corresponding address information in real time,user can obtain information about nearby automation devices through the software for viewing and editing,improving the working efficiency.The on-site management and remote operation of the automation equipment can be realized by the mobile device,and the control station can keep track of the operation of all the devices at any time.

Summary of Sequential Monte Carlo Simulation Method for Reliability Assessment of Distribution Network

SONG Youle, WANG Ke, ZHU Yongmei, LIU Yong, YUAN Qiushi

2020, 0(1):  90-93.  doi:10.16628/j.cnki.2095-8188.2020.01.015

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This paper introduced the importance of reliability evaluation of distribution network and the commonly used reliability evaluation algorithms.The basic principle of sequential Monte Carlo simulation method was introduced in detail,and the advantages of its reliability evaluation were pointed out.Finally,the sequential Monte Carlo simulation method was further studied considering the sequence arrangement of component faults and planned blackouts,the sampling method after adding distributed generators and the convergence judgment method,which can provide some reference for subsequent reliability evaluation.

Unit Commitment Considering Active Optimal Transmission Switching

DU Mengke, REN Yanfeng, HU Yongxin, CHENG Haozhong

2020, 0(1):  94-99.  doi:10.16628/j.cnki.2095-8188.2020.01.016

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The grid topology is fixed in the traditional unit commitment,regardless of the transmission line active breaking.In order to solve the problem of transmission line congestion caused by unit commitment,this paper takes into account the change of power grid topology in the traditional unit commitment model,and establishes unit commitment model which takes active optimal transmission switching into consideration.The model includes network security constraint.By introducing Big-M method,the active optimal transmission switching model is transformed into the mixed integer linear programming formulation.In order to speed up the solution of the model,this paper uses genetic algorithm combined with mixed integer linear programming.This paper not only can give the unit commitment schemes at each time,but also get the optimal network topology of each period.An example of a modified IEEE-RTS 24 nodes indicates that the combination of units commitment taking into account active optimal transmission switching can be more effective in reducing the overall cost of the system.