bluuebunny/crossref_metadata_2025 huggingface dataset:
Cabin Temperature Regulation-based Charging Strategy for Electric Vehicles Under 5G
Authors: Chenxu Zhao , Chenggang Yang , Ziti Cui , Xianjun Zeng , Zifan Fan , You Zhou
Published: February 2021

As massive EVs are introduced rapidly, large-scale disordered charging loads appear in the power grid, which may lead to "peak plus peak" and overload for local substations. With the rapid development of 5G, the data transmission of large-scale EVs is suggested to help optimizing the orderly charging strategy under cabin temperature control and load control in EVs in this paper. The charging time, charging cost and substation capacity are considered as constraints, so as to optimize the charging period of EVs. It seems that the temperature control dispatching can effectively reduce the disordered charging load of EVs, smooth the overall load curve of the power grid and result "peak shifting and valley filling" of the power grid.
Wind and Solar Integrated Power Prediction Method Research Based on DT-CWT and LSTM
Authors: Ren Yuan , Wang Jinhao , Yang Chaoying , Xiao Chang , Li Shengwen
Published: February 2021

It is very important to improve the wind and solar integrated output power load forecasting technology with the rapid construction of wind and solar hybrid power supply system and the increasing network complexity of microgrid energy system. On the basis of traditional load power forecasting, this paper proposes a wind and solar integrated power prediction method based on dual tree complex wavelet and long short time memory network. In this method, the original power data of photovoltaic and wind power are denoised by DT-CWT. After data reconstruction and transformation, the processed data are trained by multi-port long and short time memory network prediction model, so as to achieve wind power optical integrated power prediction purpose. Finally, the field data of wind and solar hybrid power supply system is used to verify the model. The results show that the method can effectively reduce the impact of power noise during prediction, and improve the accuracy of power prediction of wind and solar hybrid power supply system.
System Stability Risk Quantitative Assessment for Island Operation with PV Plants
Authors: Zhao Haibo , Li Qi , Gao Jin , Zhang Yanhui , Zhang Zhi , Song Junxiao
Published: February 2021

There are stability risks after PV plants drop into island operation, especially in case of unintentional islanding caused by grid faults and the islanding-state detection device fails to operate in time. In order to estimate those risks, firstly, the mechanism of three factors (power difference, PV permeability and motor inertia) influencing the stability characteristics of the island system in a short time after PV unintentionally dropped into island operation is analysed theoretically. Then the electromagnetic transient model of the PV station is established. According to above, the modified Dali Grid integrated with a PV station is modelled in PSCAD/EMTDC, verifying the theoretical analysis conclusions by simulation. Finally, quantitative risk index and assessment method about PV station dropping into islanding are proposed according to the simulation results, which provide the theoretical basis for the stability risk estimation.
Design of online uninterruptible power supply with AC output
Authors: Jiang Ganlin
Published: February 2021

This paper shows the design of an on-line uninterruptible power supply with STM32 as the main controller. It contains rechargeable batteries as the energy storage device and uses inverter technology as the core which can make 29V∼42V AC input to 30V AC RMS output. The system uses STM32 as the control core, it is divided into main controller, autotransformer module, rectifier bridge module, PFC module, inverter module, booster module, battery pack, current and voltage detection module. When the utility power is connected, it supplies power to the inverter module and if it is disconnected, the main control terminal allows the battery to supply power to the inverter module in time, thereby realizing online uninterrupted power supply. Experimental results show that this system can supply power to the load without interruption, and has a good load regulation rate and voltage regulation rate.
A NDO Based Attack Detection Observer and Isolation Strategy in Distributed DC Microgrid with FDIA
Authors: Zhang Daming , Zhang Chuanlin
Published: February 2021

In this paper, an isolation scheme is proposed to mitigate adverse effects of false data injection attack (FDIA) in cyber layer of distributed DC microgrids. Firstly, the attack signal in communication link is effectively estimated by the nonlinear disturbance observer (NDO). Secondly, an isolation mechanism is designed to distributively insulate the misbehaving agent of cooperative control, and further to mitigate adverse effects on voltage regulation and power sharing in DC microgrids. Thirdly, considering the changes in load distribution during the process of isolation, a domination controller for stabilizing DC/DC boost converter is introduced to ensure the rapid voltage convergence with accurate tracking over a wide operating range. Simulation results are conducted on an islanded DC MG test system to verify the effectiveness of the proposed scheme.
Economic dispatch of household PV-BS-EV microgrid under TOU tariffs
Authors: Yi-wei MA , Shi-qiang DING , Qi-ming JING , Xian-lun TANG
Published: February 2021

Economic dispatch is a hotspot issue of household hybrid energy microgrid. This paper gives modellings of a typical household microgrid integrated with solar PV, battery energy storage system (BS) and electric vehicle (EV). The charging/discharging strategy of EV and its coordinated dispatch strategy with supply side units are presented to solve the minimum system operation objective under time of use (TOU) tariffs. The simulation results show that the proposed method is effective and feasible.
Research on Aggregation Model of Wind Farm Based on SSO Complex Torque Coefficient Analysis
Authors: Xunwen SU , Hanqing CUI , Yuming PEI , Dongni ZHANG , Pengyu AN
Published: February 2021

In order to study the influence of the clustering aggregation of doubly-fed wind turbines (DFIG) in the wind-fire bundling system on the system subsynchronous oscillation (SSO), the expression of the DFIG output active power on the electrical damping De of thermal power units is first derived. Then the wind-thermal bundling system is built based on the IEEE first bench mark, and the wind farm is aggregated to several groups according to the rated power. The complex torque coefficient method is used to analyze the two cases of the same running state of the wind turbine and the difference of wind speed between the turbine and verified by time-domain simulation. The results show that the difference in wind speed within the DFIG groups has little effect on the system oscillation frequency before and after the aggregation of the wind farm, but there may be a slight error in the electrical damping coefficient before and after the aggregation,but the error does not affect the trend and analysis of damping characteristics of system. When studying the influencing factors of wind-fire bundling system SSOthe aggregated model can be uesd to improve simulation efficiency.
A Defect Detection Method Based on Faster RCNN for Power Equipment
Authors: Cheng Yang , Xia Lingzhi , Yan Bo , Chen Jiang , Hu Dongsheng , Zhu Lvfu
Published: February 2021

With the wide application of infrared image acquisition technology in power inspection, a large number of infrared images of power equipment have been obtained. The traditional machine learning method has low accuracy and poor generalization. Therefore, in this paper, the deep learning technology is applied to infrared image detection of power equipment, and a defect detection method based on Faster region convolution neural network (RCNN) is proposed. In this method, the deep residual network is used to extract image features, and the regional proposal network is optimized according to the shape characteristics of power equipment, and the network is trained with the help of shared convolution layer. The experimental results show that the proposed method has high detection accuracy, good robustness and generalization ability.
A Coordinated Dispatch Method for Receiving-end Grid Considering HVDC Power Characteristics
Authors: Jiao Shumei , Chen Yuanyang , Cao Yijia , Liao Changfeng , Tan Yi , Li Yong , Zeng Zilong , Guo Siyuan
Published: February 2021

The power injection from the high-voltage direct current (HVDC) transmission system has a significant impact on the operation and scheduling of the receiving-end power system. In this paper, considering the unipolar blocking faults and the power characteristics of the traditional HVDC system (i.e., LCC-HVDC), a multi-period dispatch model is proposed for the receiving-end power system to achieve the coordinated optimization of various dispatchable resources such as the power injection of LCC-HVDC and the local generation. In the proposed model, the constraints such as those related to the number of LCC-HVDC power adjustments, branch power flow, bus voltage and the output of local generators are taken into account, and its objective is to minimize the total power purchase cost of the receiving-end power system. To solve the proposed model efficiently, the method for determining the time of changing LCC-HVDC power injection is first proposed, and then its results are used to further solve the proposed multi-period dispatch model of the receiving-end power system. The simulation results show that the dispatch method proposed in this paper can effectively deal with LCC-HVDC unipolar blocking faults, and reasonably optimize the power purchase cost of the receiving-end power system.
Design of Capacitor-less LDO applied to Low Power Supply with High-precision Bandgap
Authors: Li Sheng , Xin Xiaoning , Jian Ren , Pang Jinghang
Published: February 2021

This paper proposes a capacitor-less low dropout regulator (LDO) applied to low power supply to meet the needs of low power consumption and highly integration. In order to improve the transient response of the system, a dynamic bias circuit is designed, which can automatically track the change of load current. In addition, the temperature coefficient of bandgap reference in conventional LDO is generally 20-100 ppm/°C. The bandgap reference circuit proposed in this paper can achieve 1.73 ppm/°C without trimming, and the accuracy is better than 1% at all process corner. The design and simulation are based on TSMC 0.18 μm CMOS process, the simulation results show that the LDO output voltage is 1 V when input power supply voltage is 1.2 V. The proposed regulator can operate with a minimum dropout voltage of 200 mV when load current is 50 mA. The maximum undershoot and overshoot voltages are 34 mV and 28 mV, respectively, with 1mA-50mA and 50mA-1mA step load current.
Regional Energy Community Planning Considering Wind Power Uncertainty
Authors: Zhao Long , Pan Yueming , Qiu Peng , Xuan Lv
Published: February 2021

Large-scale uncertain wind power grid connection will put forward higher requirements for system planning, and also bring challenges to power quality, power reliability, safe and economic operation of power system. In view of the problem of considering the uncertainty of wind power scenarios in system planning, in this paper, the k-means clustering method is used to cluster and reduce the historical data of wind farms to obtain typical days of wind power output. The regional energy community planning model that considers the uncertainty of wind power and uses the minimum planning cost as the objective function is established. The obtained typical wind power scenarios replace the wind power scenarios of the regional energy community in the planning period for simulation analysis. The results based on the simulation software show that the scenario method can improve the feasibility and effectiveness of planning for wind power factors in the regional energy community, promote the scale development of wind power, reduce the wind abandonment rate and planning costs to maximize the benefits of planning.
A novel fast SVPWM method based on two-stage transformation for three-level inverter
Authors: He Li , Wang Bin , Liu Jiang , Yan Yong
Published: February 2021

Compared with the two-level inverter, the three-level inverter has excellent performance in pressure voltage switching loss and harmonic applied to the fields of the speed regulation and new energy generation. However, the computational complexity of the space vector pulse width modulation (SVPWM) method for multilevel inverter restricts the implementation on low cost microprocessor. This paper proposes a novel fast SVPWM method for three-level inverter to convert the space voltage vector in the three-level space to the two-level by vector subtraction with the central vector. The conduction time of each switch can be computed quickly so that the runtime is reduced significantly. Finally, the experimental results verify the effectiveness and practicability of the new space vector modulation algorithm based on two-stage transformation.
Architecture Design of Digital Twin Platform for AC&DC Hybrid Transmission System with MMC-HVDC
Authors: Zhou Jingsen , Wei Jinxiao , Xie Gangwen , Ran Li , Zhang Youqiang
Published: February 2021

With the development of power electronic devices, more and more high-power power electronic devices were used in high-voltage DC transmission. The purpose is to improve the stability of grid and the acceptance ability of new energy. The Yu-E flexible DC back-to-back interconnection project is a typical example of this technology. However, due to the large number of power electronic devices and sub modules, it brings many difficulties to the analysis of AC&DC hybrid power system, Especially when there is a lot of new energy penetration. This paper is based on the concept of digital twin, equivalent to the MMC sub-module as a series connection of the power supply and its on-resistance, then based on actual operating parameters and grid planning, a set of digital twin platforms for AC&DC transmission systems with large-scale new energy integration has been established. Comparing the running results of the digital twin model with the actual running state, the method and architecture described in this paper have certain practicability and effectiveness.
Dielectrophoresis Assembly of Nanowires in a Conductive Island-based Microelectrode System
Authors: Du Shan , Ding Haitao
Published: February 2021

Dielectrophoresis has attracted much attention in the field of nanowire assembly because of its high precision, high efficiency. However, the research on the mechanism related to the motion trajectory in the process of nanowire assembly is still in development. In this paper, a conductive island-based microelectrode system is reported to optimize the dielectric assembly process of nanowires. The existence of conductive islands can improve the positioning accuracy of nanowires during their assembly process. A simulation model of nanowire dielectric assembly based on the conductive island-based microelectrode system is established to analyze the dielectrophoresis force and motion trajectory of the nanowire during the assembly process. The simulation results show that the final position of the nanowire is mostly located in the gap between the electrode and the conductive island due to the dielectrophoretic force in the near field. Moreover, the nanowire has a tendency to move parallel to the tangent of the electric field line due to the action of the dielectrophoretic force. Therefore, the nanowire connects the electrode and the two ends of the conductive island in parallel.
Design of monitoring system for redundant communication power supply based on ZigBee
Authors: Zhang Shujuan , Ma Wanli , Yu Mengxi , Zhang Feng , Chen Junwei
Published: February 2021

Aiming at the problems of poor maintenance effect and large measurement error of traditional communication power supply monitoring system, a redundant communication power supply monitoring system based on ZigBee is designed. The sensor and power supply cable are installed, the battery working state parameters are collected and cleaned, compressed and fused. The MSP430F149 single chip microcomputer is used to realize the high-speed processing of field information and optimize the configuration of hardware structure. The software maintenance process of the complete redundant communication power supply monitoring system is designed. The logic editing technology is used to correct, adjust and improve the system software. The mathematical model of hardware maintenance is established. The most reasonable monitoring and measurement of redundant communication power supply is calculated by ZigBee method to realize the effective monitoring of communication power supply. The experimental results show that the hardware operation effect of the design system is good, and the measurement error can be effectively reduced.
An Optimal Decision-Making Method for Power Market Transaction Based on Renewable Energy Multi-Scenario Forecast
Authors: Cai Jiarong , Lai Weiwei , Qian Zhenghao , Huang Kang , Zhou Rui , Huang Zhisheng
Published: February 2021

In order to improve the adaptability of power market transaction to the uncertainty of renewable energy, the multi-scenario forecast model of renewable energy is studied and an optimal decision-making method for power market transaction based on renewable energy multi-scenario forecast is proposed. Multi-scenario forecast of renewable energy is a forecast result composed of multiple forecast curves, which is an uncertain forecast model in nature. The optimal power market transaction decision-making method takes the lowest expected cost and the lowest loss of renewable energy as the optimization objectives and comprehensively considers the constraints including power balance, power network transmission capacity and so on. Finally, a case study based on IEEE-30 buses system shows that this method can fully consider the impact of renewable energy uncertainty on trading results and has a significant effect on improving the efficiency of power market transaction results.
Innovative method for state of energy estimation based on improved Cubature Kalman filter
Authors: Zhou Xinan , Zhou Sida , Li Qiangwei , Fan Zhiwei , hua Yang , Yang Shichun , Shao Yulong
Published: February 2021

As the increasing concern of driving ranges for electric vehicles, the precision of state of energy (SOE) estimation contributes to the better performance of battery management. In this article, an innovative method based on 5th-order simplex square-radius cubature Kalman filter is developed to achieve the precise and robust estimation for SOE on electric vehicles. Based on second-order equivalent circuit model and particle-swarm-optimization algorithm, the implementation helps the validation of SOE estimation. The max error of SOE estimation under stable condition is less than 3%, and that for dynamic stress test condition is under 4%. Moreover, the robustness is investigated based on diverse deviations on initialization, delivering the future potential applications on embedded system on cloud-controlling.
Analysis of ZVS Realization with Consideration of Secondary Parasitic Capacitance for High Frequency GaN-based LLC Resonant Converter under DCM Mode
Authors: Li Linkai , Min Run , lyu Dian , Zhang Desheng , Tong Qiaoling
Published: February 2021

LLC resonant converter can achieve zero voltage switching (ZVS) for primary side devices and zero current switching (ZCS) for secondary side rectifiers while operating in discontinuous conduction mode (DCM). However, the parasitic capacitance significantly affects the ZVS realization of primary side switches for high frequency GaN-based LLC converter. In order to reveal the influence, this paper analyses ZVS transition process with consideration of secondary parasitic capacitance in a high frequency GaN-based LLC resonant converter under DCM mode. Then, an accurate model during ZVS transition is derived. To verify the analysis and the derived model, a 250V rating input and 270V/6.6A rating output GaN-based LLC converter prototype operating at 500 kHz is built. The experimental results are consistent with the theoretical analysis.
Design and PLC Realization of Elevator Control Based on LOOK Algorithm
Authors: Wang Yanlin , Jiang Tao
Published: February 2021

The LOOK algorithm is widely used in disk scheduling algorithms for its short seek path. Because its dispatching presents the corresponding characteristics of one-way priority and is similar to the elevator dispatching process, the LOOK algorithm is used to realize elevator dispatching. Through PLC logic operation, the elevator can run stably and efficiently with LOOK algorithm. At the same time, it can reduce the average riding and waiting time of passengers, and improve the operation efficiency of elevator.
A mine digital integrated protector with harmonic detection and analysis function
Authors: Huang Hesong , Wang Jiahao , Sun Zhengqiang
Published: February 2021

Aiming at the protection problems and harmonic detection problems of motor circuit, lighting signal circuit in coal mine, a mine digital comprehensive protector based on STM32 is designed. The protector can realize the protection and harmonic detection of motor circuit, lighting circuit and signal circuit in coal mine, and use windowed interpolation fast Fourier algorithm to calculate and analyze harmonic. The protector has the functions of under voltage, over-voltage, overload, short circuit, three-phase unbalance, open phase, leakage locking, insulation danger indication, over temperature, under temperature, wind power and gas locking, harmonic analysis, local storage, remote control and other functions. The experimental results show that the system design scheme is feasible and effective.
Active Fault-tolerant Control Research of Multi-Agent System
Authors: Wang Jun , Zhang Jie
Published: February 2021

Aiming at the multi-agent system with directed topology, taking into account the possible failure of any actuator of each agent, the design of the robust H
∞ active fault-tolerant controller for the multi-agent system is studied using the compensation control. First, introduce distributed intermediate variables to establish an observer-based closed-loop error model of the multi-agent system, and use the H
∞ control to design a fault detection observer to estimate the fault information of each agent's actuator in real time. Once the accurate fault information is obtained, immediately adjust online control gain to compensate for actuator failure. Finally, a simulation example verifies the effectiveness and feasibility of the proposed method.
Active fault tolerant / intrusion tolerant cooperative control of discrete NCS based on sliding mode variable structure
Authors: Wang Jun , Meng XiaoLi
Published: February 2021

Aiming at the actuator failure in the linear discrete networked control system (NCS) and the denial of service network attack (DoS) on the actuator side, under the discrete event trigger mechanism, an active fault-tolerant/intrusion-tolerant cooperative control method based on sliding mode variable structure is proposed. This method applies the fading adaptive Kalman filter (AKF) to jointly estimate the system state, fault parameters and attack parameters, obtains the estimated value of each parameter vector, and uses the estimated value satisfying the event trigger condition to reconstruct the controller. In this way, system errors caused by actuator faults and attacks are corrected, fault-tolerant and intrusion-tolerant coordinated control is realized, and the purpose of saving network resources can be achieved. Finally, the effectiveness of the control method is verified by simulation.
Improved fast three vector predictive current control of permanent magnet synchronous motor
Authors: Fang Zhiyuan , Luo Chen , Sun Sifan
Published: February 2021

In order to improve the steady-state performance of the traditional model predictive control and reduce the amount of calculation of the control algorithm, this paper proposes a new fast three-vector predictive current control algorithm, which uses the principle of deadbeat control of the dq-axis current to calculate the reference voltage vector, and obtains the reference voltage vector position through sector judgment, combined with the three-vector model predictive control algorithm, the optimal voltage vector is directly applied to the motor, without the need to predict the behavior of the system under the voltage vector, which greatly reduces the amount of calculation. At the same time, due to the introduction of three vectors, three functions are applied in one cycle. The voltage vector greatly improves the steady-state characteristics of the system. The simulation results show that the proposed new three-vector predictive current control algorithm can reduce the amount of calculation and improve the steady-state characteristics of the system.
The Power Control Method of Data Center Based on Cloud- Edge Collaboration
Authors: Zhao Junjie , Hou Yucheng , Liu Liu , Xie Feng , Mao Xiang , Luo Pan , Wang Jinxin , Zhang Zhiqiang , Deng Jiang
Published: February 2021

Data centers have the characteristics of huge energy consumption and strong power fluctuations. To solve the problem of unstable supply and demand such as frequent power fluctuations in the micro-grid of the data center using renewable energies, this paper establishes a controllable load model of server clusters based on the task migration mechanism by analyzing the various tasks and characteristics of large cloud data centers, as well as edge computing nodes. Through the collaborative optimization control of edge and cloud computing tasks, and dynamically adjusting and migrating the server cluster load, a new data center tie-line power control method is proposed. The results of calculation examples show that the method can achieve power smoothing of large-scale cloud data center tie lines through cloud-edge collaborative control.
Distributed cooperative formation of multiple unmanned ships based on KF
Authors: Liu Wang , Lv Xiafu
Published: February 2021

To study the cooperative formation of unmanned ships, and for the influence of noise signals in multiple sensors of multiple unmanned ships, a formation mode based on distributed Kalman filtering is proposed. The position information of the main ship is determined first, and the auxiliary ship sets the desired position of the auxiliary ship as the target of the auxiliary ship according to the position information of the main ship, and finally keeps the formation to move toward the target. The target tracking of single unmanned ship and multiple unmanned ship systems is simulated. The research results show that not only the estimated trajectory of the single unmanned ship is greatly optimized, but the trajectory of each unmanned ship in the multiple unmanned ship system is also very good. It fits the expected trajectory very well and meets the expected requirements.
Key Technologies and Development Status of Smart City
Authors: Zhong Yuanchang , Sun Lili , Ge Chenhao
Published: February 2021

In the 21st century, the rapid development of Internet information technology has provided a trend and direction for breaking the construction concept of traditional cities and building new smart cities. However, with the rapid development of smart cities, timely attention and research on the key technologies and development status of global smart cities, so as to provide directions and references for the further research of smart cities, has become a research hotspot of smart cities in the new century. Firstly, this paper studies the development status of smart cities by studying a large number of domestic and foreign literatures. Secondly, it further studies several key technologies and their development status. Through the research, it is concluded that the rapid development of smart cities at the present stage has achieved outstanding achievements in various application fields of smart cities, but it is urgent to break the bottleneck of key technologies and help the further development of smart cities by combining with the application of key technologies of smart cities in the new era.
Speed sensorless control of permanent magnet synchronous motor based on robust adaptive algorithm
Authors: Wang Zeng Hui , Zhang Jun Hong , Zhang Yin Heng , Xiao Huan Yu , Zhang Xiao Chen
Published: February 2021

In order to solve the problem that the parameters of the regulator and the actual parameters do not match due to the time-varying motor parameters in the operation of PMSM, this paper adopts a robust adaptive control strategy based on linear matrix inequality (LMI) based on the model reference adaptive method (MRAS) to consider the uncertainties of the motor parameters in the state equation of the motor control system, the controller parameters are obtained by solving the LMI. The simulation model of PMSM speed sensorless control system is built in Simulink. The simulation results show that the system can track the given speed well and has strong robustness when the motor parameters change.
PCCPS-PWM based vehicle-network high frequency resonance suppression method
Authors: Ding Yong , Wang Tiesheng , Zhang Xinyu , Zhang Yuxi , Miao Yifei
Published: February 2021

In recent years, the safe and stable operation of electrified railways has attracted more and more attention. In particular, the stability of vehicle-grid coupling, which focuses on the phenomenon of vehicle-grid high frequency resonance (HFR), has become a hot research topic. Based on the instability mechanism of vehicle-grid coupling, and from the perspective of grid-side converter modulation strategy, measures to suppress HFR are further proposed. Based on the improvement of commonly used modulation strategies, Periodic Control Carrier Phase-Shift Pulse Width Modulation (PCCPS-PWM) is proposed, this solves the HFR problem caused by the switching characteristic frequency harmonics caused by the inaccurate phase shift angle between the grid-side converters. And it is verified by Matlab simulation and hybrid electric train sets.
A design of self-learning intelligent infrared remote controller
Authors: Lu An , Gong Yingkun , Xiong Deyi
Published: February 2021

This paper presents a self-learning intelligent infrared remote control system for Android system. In this paper, STM32F103RCT6 chip is selected as microprocessor, infrared integrated receiver head VS1838 and infrared light emitting diode are used as infrared receiving/transmitting module. The communication of experimental platform system is established to realize the management and control of household appliances by mobile terminal.
Research on Dual Mode Unified Control Strategy of Grid Connected Inverter Based on Droop Control
Authors: Zhang Ying , Jiang Wei , Wang Xiaohuan
Published: February 2021

There is a big difference between the two modes of grid connected inverter in micro-grid operation. In order to avoid large voltage and current impact, advanced control strategy is needed to realize smooth conversion during operation mode switching. A droop control method based on voltage amplitude change rate is proposed, which is suitable for dual-mode unified control of inverter. While ensuring the stability of the system, the reactive power of the inverter can be accurately shared during islanding operation. This method can realize smooth switching between grid connected inverter and islanding mode. The feasibility of the method is verified by simulation and experiment.
A wireless transmission coupling structure with low electromagnetic force disturbance and stable coupling coefficient
Authors: Xing Zikang , Yan Kui , Han Gao , Li Xiaoping , Liu Yanming
Published: February 2021

In the inductive wireless power transmission, electromagnetic force, which between the primary part and the secondary part, may cause the non-contact free motion and cause bad side effects on transmission. In order to calculate the force, magnetic vector potentials differential equations, based on linear array, are built, and the expression of the electromagnetic force is produced by solving this equation system.
Passivity-based Control of Voltage Source Converter Based On Mixed Sensitivity H∞
Authors: Li Yaxin , Yang Jie , Fang Rengcun , Xu Hanping , Yang Ruixi , Zhang Chengbiao
Published: February 2021

Considering the uncertainty of the control object, this paper aims to design the passivity-based control of voltage source converter based on mixed sensitivity H∞. Firstly, the plant model of VSC converter has been deduced and proved by simulation. Then the controllable of plant has been analyzed. Furthermore, based on mixed sensitivity H∞ theory, the performance weight function and passivity-based control have been designed. Finally, proved by simulation comparison, this control has more accurate and robust dynamic performance than the traditional ac voltage control.
A dust sensor monitoring system using Wi-Fi mesh network
Authors: Guo Zeyu , Ma Xiaolin , Zhang Pei , Liu Zhaoyang
Published: February 2021

This paper proposes a dust sensor monitoring system using Wi-Fi mesh network, including wireless dust sensor node and Wi-Fi mesh networking procedure. The wireless sensor node is made by integrating a dust sensor based on GP2Y1010AU0F chip, a STM32F103ZET6 chip as its MCU, a Wi-Fi module as its wireless transceiver, and a LCD screen as its user-interface. The dust sensor takes the light scattering method, measuring the flash frequency and the duration reflected by particles in the air flow. Dust sensor nodes are networking by Wi-Fi mesh network. Practical experiments validate the effectiveness of the proposed system. The measuring error of dust concentration is less than 5%. As the network is made up of 8-10 nodes, if the root node is disconnected, the network recovery time is less than 9 seconds while the other nodes’ is less than 5 seconds.
Improved Analysis Model of SiC Power MOSFET with Staged Critical Parameters
Authors: Yuan Dakang , Zhang Yiming , Wang Xuhong , Zhang Bin
Published: February 2021

Silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) have great advantages in improving the power density and performance of power converters due to the high switching frequency, high operating voltage. However, the increase in switching frequency is also increasingly inflicted the voltage and current stresses to the parasitic elements of the SiC MOSFET, which restricts the device’s optimal performance. In addition, many parasitic elements of SiC MOSFET are coupled with each other during the switching process, which makes the analysis complicated and calculation cumbersome. This paper presents an analytical model for SiC MOSFETs, which identifies and selectes the dominant elements and key variations of each stage separately according to the change stages of major variables. The complexity of the model is reduced while the accuracy is guaranteed. Using this model, the voltage and current switching rate of SiC MOSFET can be quickly solved, and the impact mechanism of each critical parameter can also be revealed clearly. A double pulse test circuit composed of a 600V/20A SiC MOSFET is set up and experimental results are obtained to verify the accuracy of the proposed analytical model.
Numerical Study on the Influence of Non-uniform Demagnetization of Permanent Magnet Synchronous Motor
Authors: Wu Guopei , Yu Yinquan , Yang Jinwen , Chen Qiping , Zhou Shaowei
Published: February 2021

To study the influence of the non-uniform demagnetization of permanent magnets (PMs) on motor performance, this paper takes a two-phase four-pole Permanent Magnet Synchronous Motor (PMSM) as the research specimen. The influences of torque, phase current, back electromotive force (back-EMF), and radial magnetic density with different grades and types of demagnetization are analyzed. The simulation results show that as the degree of nonuniform demagnetization increases, the output torque and radial magnetic density gradually decrease, on the other hand, the phase current gradually increases. According to the change law of the amplitude of some harmonics of the back-EMF, it can be judged whether the motor has non-uniform demagnetization. This research conclusion can provide a theoretical basis for fault diagnosis of motor demagnetization.
Adaptive climbing motion of snake robot based on joint decoupling and extended Kalman filter
Authors: Xiao Wenyu , Gao Yong , Wei Wu , Zhang Jie , Tan Xiaoman
Published: February 2021

This paper proposes a decoupled gait control function to solve the adaptive transition problem of the snake robot climbing the rod with variable diameter. Firstly, the Sigmoid function is combined with the general gait control function to achieve the decoupling control of the robot joints. Then an adaptive adjustment algorithm of key control parameters is designed based on the extended Kalman filter (EKF) to realize the decoupling gait changes continuously and compliantly as the environment changes. Finally, the physical meanings of the key control parameters are reiterated by simulation, and their influence on the decoupling of climbing gait is analyzed. The smooth transition climbing experiments of the snake robot on rods with different diameters verify the effectiveness of the decoupling and adaptive algorithm.
Replacement Scheme of Drive Boards For Traction Inverter Module of Beijing DKZ31 Metro Vehicle
Authors: Zhang Fan , Zhang Lujun , Liang Shuangqing , Sun Lu , Dai Xiaoteng
Published: February 2021

Nowadays, the status of metro in urban traffic is particularly prominent in Beijing. How to ensure the normal operation of metro train is particularly important. At present, the problems of high failure rate, high maintenance cost and long maintenance cycle exist in the drive boards of imported traction system. In view of the above problems, this paper put forward the alternative scheme of drive boards on DKZ31 metro, and carried out the test work. On the basis of ensuring the safety and reliability, the maintenance cost is greatly reduced and the maintenance efficiency is improved. At present, the samples of drive boards have been completed and the relevant functional tests have been carried out. The test results show that the performance of the drive boards is good, which meets the requirements and achieves the predetermined goal.
Using variational regularization method of electrical impedance tomography to reduce the position error of human arm
Authors: Du Donghai , Huang Kun , Liu Xingmou , Li Qingdu , Zhang Jiajia
Published: February 2021

This paper investigates how to reconstruct human arm images using electrical impedance tomography. A simplified arm model is first established. The comparison between the Tikhonov regularized reconstruction algorithm and the Variation regularized reconstruction algorithm is then made. The results show that the Variation regularized reconstruction algorithm has the lesser position error on the organizational junction edges and is basically overlap with the target area of the model. How to eliminate the artefact of the reconstructed image needs to be further investigated.
Design and analysis of the variable-axis structure before and after the large magnetic block of the charging and discharging magnetic adsorption robot
Authors: Ming-lei LI , Yu-lian ZHANG , Xin CHEN , Shi-fei WU
Published: February 2021

The new type of magnetic adsorption robot for charging and discharging the outer surface of ships has unique advantages in derusting the outer surface of ships. Due to the relatively large volume of the charging and discharging magnetic block, it is difficult to rotate around the bearings at the front and rear ends through the track. This paper designs a variable axis structure for large magnetic blocks before and after walking. Use NX to complete the construction of the 3D model, and import the 3D model into ANSYS for structural analysis through the association with ANSYS-Workbench. The deformation and stress analysis of parts provide theoretical support for the safety and stability of the Variable axis structure.
Short circuit fault analysis and solution research of equipment electric gas cabinet under conductive dust pollution environment
Authors: Mei Ke , Li Xiaofei , Gu Chao
Published: February 2021

The production of conductive dust not only pollute the environment, harm people's health, but also bring great harm to the safe operation of electrical equipment. Such as shorting electrical equipment, electrical switch according to touch bad, poor ventilation, etc., it is easy to cause equipment electrical cabinets failure problems, in order to strengthen the reliability of enterprise production, for the timely and effective maintenance of the equipment failure, and take effective measures to guarantee with the safe operation of the equipment electrical cabinets in conductive dust environment. A great deal of work has been done in this paper to prevent the harm of dust to the electrical equipment and remarkable results have been obtained.
Research on Accurate Impact Point Prediction Methods of Heavy Rocket Debris
Authors: Tao Liu , Chao Kou , Li Ma , Jing Yang , yuchao Wang , Yu Zhao
Published: February 2021

Driven by the demands of rocket launching safety and major scientific research projects, this study probes into the process of impact point prediction for heavy debris from rocket launching. By establishing the basic model of impact point prediction, an analysis of error sources of impact point prediction is conducted to define the research direction of improving the accuracy of impact point prediction. The calculation model of heavy debris impact points introduces the concept of comprehensive analysis of big data. Based on the current situation of equipment, it makes full use of valuable measured data resources of rocket launching and the data information of the measured flight and landing area in multiple samples. Using statistical methods, a back calculation of air resistance and velocity correction affecting the impact point calculation is made, thus forming an accurate calculation model of heavy debris impact points. The data validation shows that the real-time prediction accuracy of this model has been greatly improved compared with the original model, which meets the research expectations.
Study on Speech Recognition Method of Artificial Intelligence Deep Learning
Authors: Leini Zhang , Xiaolei Sun
Published: February 2021

This paper briefly describes the basic principles and related theories of speech recognition system, points out the existing problems of speech recognition technology of artificial intelligence deep learning, analyzes the speech recognition methods of artificial intelligence deep learning, puts forward the optimization methods of speech recognition technology of artificial intelligence deep learning from the aspects of strengthening targeted feature recognition of speech system, repeatedly carrying out simulation training of speech recognition and combining acoustic features with sports features, and forecasts the future prospects of speech recognition methods of artificial intelligence deep learning.
Fine-grained image classification based on attention-guided image enhancement
Authors: Lu Junming , Wu Wei
Published: February 2021

Extracting distinguished fine-grained features is essential for fine-grained image recognition tasks. Many researchers use expensive manual annotations to learn to distinguish part models, which may not be possible in practical applications. Unlike previous strongly supervised fine grained classification networks that require additional image annotations, weakly supervised fine grained image classification only requires label annotations. Recently, image enhancement has been increasingly used in network structures, but random enhancement will lead to background noise and filter out irrelevant areas. In this article, we propose a weakly supervised fine-grained image classification network based on attention-guided image enhancement to study the effect of image enhancement on the classification network. In detail, we use the backbone network to generate the feature map of the image, then generate the corresponding attention map through a custom mask, and use the attention map to guide the image enhancement process (including image cropping and image dropping). We conducted experiments on three commonly used fine-grained image classification datasets, and achieved sota effects in CUB, FGVC-Aircraft, and Stanford Cars.
Simultaneously Optimizing Inertia Weight and Acceleration Coefficients via Introducing New Functions into PSO Algorithm
Authors: Yang Wanli , Zhou Xueting , Luo Yulan
Published: February 2021

Because of the drawbacks of easy premature in initial iteration stages, the low convergence accuracy and slowed-down converging speed in final stages of the particle swarm optimization (PSO)algorithm therefore the simple particle swarm optimization (SPSO) algorithm with dynamic changes of inertia weight and acceleration coefficients (IASPSO) has been put forward. IASPSO algorithm provides a parameter optimization strategy by using exponential decreasing inertia weight and sine function acceleration coefficient to improve global exploration capacity. Simulation tests are carried out with classic Benchmark test functions. The simulation results show that compared with other PSO algorithms, IASPSO algorithm can converge to the better global optimization with a fast converging velocity and high convergence precision, promoting the optimization performance of the algorithm.
A new face detection method based on Faster RCNN
Authors: Yan He , Wang Xiaotang , Liu Yuhan , Zhang Yuning , Li Huan
Published: February 2021

The Non-Maximum Suppression (NMS) method based on Faster RCNN uses hard threshold to identify candidate face frames which to be detected. In complex scenes with partial occlusion of the face and uneven lighting, the phenomenon of missing and false detection of the face is prone to occur. Aiming at this problem, this paper proposes a new face detection method to extract face features through CNN, and generates a large number of face candidate frames which to be detected by the Region Proposal Network (RPN); the hard threshold of NMS is improved by linear weighting method, and the face candidate frame is screened by the linearly weighted NMS. Comparison experiment results show that on the FDDB dataset, the new face detection method in this paper can effectively avoid the false detection and missed detection of multiple faces under partial occlusion and uneven illumination, also has high detection accuracy and robustness.
Method for reducing the influence of crosstalk on quasi-distributed sensing network with time-division multiplexing fibre Bragg gratings
Authors: Wu Shengzong , Wen Hongqiao , Chen Xiaohan
Published: February 2021

A serial time-division multiplexing (TDM) quasi-distributed sensing array based on the ultra-weak reflection fibre Bragg gratings (FBGs) has been widely used in various areas. However, multiple reflections and shadow effect between FBGs with the same centre wavelength will accumulate as the number of gratings multiplexed increases, which will cause a significant increase in crosstalk of the reflection spectrum and will seriously affect the accuracy of the measurement results. In this paper, we theoretically analyse the instability of the results caused by multiple reflections and shadow effect, and propose a layer-by-layer compensation method to suppress crosstalk and improve the stability of the results. About 4000 FBGs with a reflectivity of 0.01% were multiplexed in the experimental system, and we measured the fluctuation of the centre wavelength of the grating at different distances to prove the effectiveness of the method we proposed. The experimental results show that the method proposed in this paper can greatly reduce the shift of the centre wavelength of the reflection spectrum and improve the stability of the system.