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2022 Volume 44 Issue 6
Published: 25 November 2022
  


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  • LI Qing-bo, LUO Rui, ZHAI Xu-jing, XIN Chao-shan, BIAN Jia-yu
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aiming at the problem of load forecasting and coordinated control in active distribution network, an optimal control algorithm based on multi-source optimization was proposed. The probability density function and the cumulative distribution function of demand and supply sides were used to construct the prediction model of power and load sides, and an optimal control model based on the multi-source collaboration for active distribution network was built. By introducing dynamic scale and cross factors, the global and local search abilities of differential evolution algorithm were improved, and the objective function was solved. The simulation results show that the scheduling cost of optimized distribution network decreases by more than 15%and the clean energy utilization rate is higher than 90%, with the prerequisite of nondecreasing customer satisfaction.
  • LIANG Hong-hao, WU Shao-cheng, WANG Bo, LIU Yang, LI Peng
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    Aiming at the data in compatibility problem of intelligent power communication network, a Modbus/TCP communication protocol based on DLT_645 was proposed. By analyzing the power calculation method of power communication network, the interactive demand of smart grids was discussed. According to the demand analysis results, the data transmission strategy between the intelligent meter and the acquisition terminal was formulated, and the hardware design of network interface protocol was provided. The simulation results show that the improved Modbus/TCP protocol has lower average response time, faster execution speed and higher data transmission success rate, compared with the conventional Modbus/RTU protocol.
  • CAI Wen-jia, TANG Deng-ping, LI Liang-bo, GUO Zheng, LI Yun-feng
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    Aiming at the problem that the automatic testing system of low-voltage current transformer needs to be shut down and transported for inspection in a period, an online measurement and detection method for the automatic testing system of low-voltage current transformer was proposed. By using both transfer and inspection standards, the measurement values were transferred between the hosting and the participating laboratories. The measurement values were traced from five aspects including basic errors, repeatability, consistency, miss detection rate and false detection rate, and the feedback of detection error data was completed in real time through a Shewhart control chart so as to realize the traceability and supervision of online measurement for automatic testing system. The results show that the as-proposed method dispenses with the disassembly and transport process for the inspection of automatic testing system and improves the work efficiency availably.
  • LI Yan-ping, AO Jian-yong, LI Dai-zhen, YE Jian-dong
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    Aiming at the problem that the number, location and size of distributed generators(DG)will affect the distribution network performance and the coordination of protection system when DG is connected and injected to distribution network, a feedback method was proposed to determine the capacity of DG at each node of the distribution network and avoid coordination errors. The capacity of DG on the bus in the case of inter phase no default was determined, the fault current flowing through relay was recorded, and the action time of main/auxiliary relays was calculated. The DG capacity was repeatedly adjusted until the action time difference between main and standby relays was less than the coordination time interval, and this value was finally selected as the minimum capacity of DG on the bus. The simulation results show that the as-proposed method can calculate the capacity of DG when relay coordination can be maintained in different modes.
  • TANG Chao, XIANG Si-yu, ZENG Zuo-lin, ZHANG Ju-ling, ZHANG Ling-hao
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    Aiming at the problems of reactive power shortage and harmonic interference in the power system caused by electrical equipment, a device and control strategy based on SVG for dynamic reactive power compensation and harmonic suppression of power supply system were proposed. A voltage bridge reactive power compensation system was established by a current double closed-loop control system based on dq0 detection method and was connected to a 10 kV distribution network in a parallel connection mode. The voltage control of outer ring and the rapid response of the reactive power of inner ring were accomplished, and the accurate control of SVG reactive power compensation was realized. The test results for 100 groups of voltage signals show that the average voltage distortion rate reduces from 32.5% before compensation to 0.41% after compensation, confirming that the as-proposed method can guarantee the security and stability of power supply system.
  • ZHANG Ai-ling, SUN Ze-fei, ZHAO Jian, LIU Ning, LEI Yong-qian
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    Aiming at the pollution of antimony in dyeing wastewater, by using the fluorescence quenching effect of Sb3+ and Sb5+ on carbon quantum dots, a rapid detection method of nitrogen-doped fluorescent carbon quantum dot nanoprobes for antimony ions in dyeing wastewater was established. The nitrogen-doped fluorescent carbon quantum dots were synthesized by a one-step hydrothermal method. The antimony ion concentration was detected by the fluorescent quenching degree of carbon quantum dots. The results show that the detection limit of antimony ions is 3.71 μg/L, and the linear range is from 10 μg/L to 80 μg/L. The index recovery ranges from 90.07% to 111.26%, and the relative standard deviation(RSD)is in the range from 0.22% to 4.88%. The as-proposed method is economical, rapid, sensitive, and it is suitable for rapid on-site detection of antimony ions.
  • WANG Zhan-jie, FANG Yin, BAI Yu
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    In order to fabricate PbZrO3 antiferroelectric thin films with high energy storage performances, the PbZrO3 thin films were prepared on the thin films of LaNiO3 elcrtrode by a microwave irradiation technology. The microstructures, electrical performances and energy storage performances of PbZrO3 thin films were investigated in relation with the microwave irradiation time. The results show that the perovskite PbZrO3 thin films with uniform grain size and dense microstructures can be obtained by microwave irradiation at 750 ℃ for only 180 s. The energy storage density of 27.3 J/cm3 and energy storage efficiency of 59% can be obtained with PbZrO3 thin films at the electric field of 1 640 kV/cm, showing good energy storage performances. Therefore, it is effective to fabricate PbZrO3 antiferroelectric thin films with high energy storage performances by using microwave irradiation in the crystallization process.
  • ZHANG Yan, HANG Jia-ning, ZHANG Wei, LIU Gong-zhao
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    In order to improve the corrosion resistance of micro-arc oxidation coating on 2A12 aluminum alloy, an asymmetric bipolar pulsed power supply was used to prepare micro-arc oxidation composite coatings with different ZrO2 nanoparticle contents, and the effect of ZrO2 nanoparticles on the corrosion resistance of micro-arc oxidation coatings on 2A12 aluminum alloy was studied. Scanning electron microscope, energy dispersive spectrometer, X ray diffractometer and electrochemical workstation and other devices were used to analyze and test the composite coatings. The results show that the corrosion current density in composite coating is the smallest when 1 g/L ZrO2 nanoparticles were added to the electrolyte, and the polarization resistance value is the highest with the best corrosion resistance. When the ZrO2 nanoparticle content in composite coating increases from 2 g/L to 3 g/L, the crack formation in composite coating gets significantly increased and the corrosion resistance of composite film declines.
  • WANG Di, WANG Dong, LI Kai-wen, WANG Li, CHEN Li-jia
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    In order to study the influence of Pt-Al coating on the oxidation behavior of DD413 alloy at 760 ℃, a single β-(Ni, Pt)Al phase coating was prepared on the surface of DD413 alloy by Pt electroplating and chemical vapor deposition aluminizing. XRD analysis, section morphology observation, element distribution and content analysis were performed on the uncoated and Pt-Al coating samples after 0.5 h to 70 h oxidation. The results show that W, Mo and Ta are enriched at the interface between the inter-diffusion zone and the substrate after the Pt-Al coating sample has been oxidized for 5 h, while TCP phase appears at the interface when it has been oxidized for 10 h. Pt-Al coating inhibits the diffusion of Cr atoms. Pt promotes selective oxidation of Al to form protective Al2O3 film over coating surface. In conclusion, Pt-Al coating can improve the oxidation resistance of DD413 alloy at 760 ℃.
  • LIU Jiu-qing, LI Xin-yuan, SUN Shu-fa
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    Aiming at the problem of poor traction with tracked vehicles on snow-covered roads, polar bear claws were used as bionic object, and the bionic track shoes with better passability was designed. The traction force of track shoes was calculated by theoretical analysis and finite element analysis, and the mechanical model for track shoes and snow-covered roads was established. The finite element analysis was carried out for the passability of different track shoes on snow-covered roads, and the design of track shoes was optimized. The results show that the main factors affecting the passability of track shoes on the snow-covered roads are track grouser height and track shoe length, while other factors have smaller impact on the passability of track shoes.
  • ZHOU Ran, YAN Ming-yin, LI Hua-chen, SUN Feng
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    Aiming at the disadvantages of low security and complex structure of existing energy harvesting suspension, a novel magnetic suspension was proposed and designed, and the effects of sprung mass, suspension stiffness and tire stiffness on the energy harvesting characteristics of magnetic suspension were analyzed through the mathematical modeling and experimental research of 2-DOF quarter suspension system. The simulation and experimental results demonstrate that the maximum output instantaneous voltage of magnetic suspension is 16 V under the input excitation with a frequency of 6 Hz and an amplitude of 4 mm, and the output voltage of magnetic suspension is inversely proportional to the change of suspension stiffness whereas proportional to the change of tire stiffness. Moreover, the accuracy of the mathematical model of energy harvesting is verified by experiments. On the precondition of ensuring the driving safety of vehicle, the energy harvesting effects of magnetic suspension can be optimized by changing the suspension system parameters.
  • HUANG Rui, XIAO Yu, ZENG Wei-jie, YE Zhi, LIU Xiao-ping
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    In order to solve the problem of high bit error rate caused by pulse interference during communication data interaction, a real time interaction method of high-speed bus communication data under Docker container was proposed. The maximum constraint conditions for communication data acquisition were set, communication data acquisition instructions were converted into the shortest path problem, and an objective function was established to complete the acquisition of high-speed bus communication data. The Docker container was used to solve the optimal communication data points, and the optimal integrated nodes of Docker container were used to adjust the positions of communication data, control the transmission efficiency for high-speed bus communication data, build a real time interaction model of high-speed bus communication data, and realize the real-time interaction for high-speed bus communication data. Experimental results show that the as-proposed method has strong anti-interference ability and reduces the bit error rate of communication data.
  • ZHAO Wei
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    Aiming at the problems during 5G communication network flow prediction, such as the inaccurate prediction which is inconsistent with the users’ needs due to ignoring the correlation between the change trend and the data contained in the flow sequence, by using an improved long and short neural network algorithm based on compressed sensing, the constraint sparse matrix with uniform convergence was established for the sampling of communication data stream to analyze actual data. The actual flow series and the flow series to be predicted were used as the input of LSTM(long and short term memory)model, and the intensive training was carried out at the same time to realize the accurate prediction of future flow data and improve the flow prediction accuracy of 5G communication networks. The TensorFlow simulation results show that the as-proposed algorithm can control the average prediction error of communication network data flow within the range from 5% to 10% and the average absolute error ranges within 3% to 8%. Compared with the communication flow predicted by conventional LSTM algorithm, the average prediction accuracy is improved by nearly 5%.
  • BAI Feng-feng
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    Aiming at the problem that the feature weights are difficult to be fixed in the process of complex software data extraction, resulting in longer software defect data extraction time and lower extraction accuracy, an adaptive software defect data extraction method based on multiple-feature weight assignment was proposed. An adaptive extraction model for software defect data was established, K-means data clustering results were obtained, and multi-feature weight features were input into a BP neural network classifier. The multi-feature weight features were allocated by a time-frequency analysis method, a defect data detection model was constructed as well, and the adaptive extraction of software defect data was completed. The results show that the as-proposed method has higher accuracy, shorter extraction time and higher extraction efficiency in the adaptive extraction of software defect data.
  • LIU Xing-rui, XU Wen-peng
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    Aiming at the problems of lower image edge matching, lower peak signal-to-noise ratio(SNR), poor stability and poor enhancement effect of traditional depth image edge enhancement methods, a mismatched edge enhancement method for depth images based on anisotropic diffusion algorithm was proposed. Depth images were obtained by a passive ranging method, image holes were removed by an interpolation algorithm, and the images were filtered according to a weighted median filtering method. Mismatched edges without noise points were detected, and an anisotropic diffusion algorithm was used to fill holes within the mismatched edges. According to the distance from pixel points to holes, an mismatched edge enhancement model was constructed to enhance the mismatched edges of depth images. The results show that the as-proposed method has higher image edge matching, maximum peak signal-to-noise ratio(PSNR), higher stability and optimal enhancement effect, in comparison with three traditional methods.
  • ZHANG Feng, WANG Wei-liang, YUAN Shuai, SUN Ming-zhi
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    Aiming at the problem of visual SLAM in the dynamic environment, in which the movement of objects will cause mismatches with feature points during the pose estimation process and the consequent poor positioning accuracy, a visual SLAM method based on convolutional neural network in dynamic environment was proposed. By using the Mask R-CNN method of convolutional neural network, ORB SLAM and Mask R-CNN algorithms were effectively integrated, and the epipolar geometry method was used to eliminate dynamic feature points. A comparative experiment with ORB SLAM2 algorithm was carried out in public data set. The results show that the as-proposed method can solve the problem of poor positioning accuracy caused by the mismatch of dynamic feature distribution points, and the positioning accuracy of optimized SLAM system is improved.
  • FU Xuan, WANG Li-ming, WANG Xue-ying, ZHANG Nan, LIU Ying-ming
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    In order to solve the problem that the nonlinear system of traditional photovoltaic grid-connected inverter is unable to achieve stable power output under disturbance, a nonlinear sliding mode control strategy based on improved particle swarm optimization algorithm was proposed. A converter model considering light intensity disturbance was established according to the working principle of photovoltaic inverter. A disturbance observer was designed to estimate the uncertain system disturbance quantitatively. In addition, the sliding mode surface and sliding mode controller were designed to control the system, and the improved particle swarm optimization algorithm was used to optimize the controller parameters. The simulation results show that the damping factor of the system decreases from -0.1 to -32.13, the effectiveness and feasibility of the strategy are verified by the hundredfold improvement of damping capacity and the favourable dynamic response, in comparison with the traditional control strategy.
  • XUE Zhi-cheng, HAN Bin
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    Aiming at the problem of vortex induced vibration(VIV)of long span bridges, a CFD method was used to simulate the flow characteristics of main girder under non-flow control, the optimal disturbance position of VIV was analyzed, and an internal breath-configuration flow control method was proposed. Wind tunnel tests were carried out to verify the control effect of breath-configuration method on the VIV response of the bridge at different disturbance locations, and the control law of VIV response of the bridge model at different control locations was obtained. The results show that the control efficiency of VIV is the highest when the disturbance locations are symmetrically arranged at the leading and the trailing edges, and the as-proposed method provides a reference for improving the stability of VIV for long span bridges.
  • LI Ke, LI Si-chen, ZHOU Qing-wei, WANG Xin-ling
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    In order to investigate the bond properties of high-strength steel wire strands in engineered cementitious composites(ECC), a total of 84 prismatic specimens and 12 thin plate specimens were subjected to uniaxial pull-out tests with consideration for the effects of steel strand diameter, anchorage length, protective layer thickness and ECC compressive strength. The results show that the pulling load-slip curve exhibits a three-stage variation law. The average bond strength can be enhanced by decreasing the steel strand diameter and relative anchorage length, or by increasing ECC compressive strength. The critical thickness of protective layer cover of high-strength steel wire strands in ECC is 3.7 times as the diameter of wire strands. Considering the effects of multiple factors, the calculation formulas of average bond strength and critical anchorage length were proposed for high-strength steel wire strands of ECC in good agreement with test results.
  • WU Bin, TAN Zhuo-ying, WANG Xian-wei, FU Ming-chun
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    In order to obtain a unified calculation formula of the ultimate bond strength of concrete filled steel tubes, abundant literatures concerning the ultimate bond strength tests of concrete filled steel tubes were studied. According to the method of statistical analysis, the unified calculation model of the ultimate bond strength of concrete filled steel tubes was proposed by taking concrete strength and diameter-thickness ratio(width-thickness ratio)as the main parameters. The results show that the ultimate bond strength increases with the increase of length-diameter ratio(length-width ratio)and confining factor, and decreases with the increase of diameter-thickness(width-thickness ratio). Generally, the ultimate bond strength increases with the increasing concrete strength. The calculation results for unified calculation method are consistent with the test results, confirming the validity of unified calculation formula, which will provide reference for the unified design of concrete filled steel tubes.