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Table of Content

    28 July 2021, Volume 55 Issue 7 Previous Issue    Next Issue
    Average Temperature Estimation for Lithium-Ion Batteries at Variable Environment Temperature
    JIANG Yu, CHEN Ziqiang
    2021, 55 (7):  781-790.  doi: 10.16183/j.cnki.jsjtu.2019.230
    Abstract ( 749 )   HTML ( 699 )   PDF (7411KB) ( 495 )   Save

    The performance of lithium-ion batteries is greatly affected by the temperature change. Therefore, it is of great significance to get the temperature information to develop the thermal management system. In order to solve the problem that the local temperature caused by the traditional temperature sensor arrangement cannot replace the overall average temperature, it is necessary to conduct studies of average temperature estimation for 10 A·h ternary nicke clobalt manganese lithium-ion batteries at variable environment temperature. First, a lithium-ion battery is modeled and the experimental platform is built to obtain the parameters which are necessary for modeling. Then, an average temperature estimation method for lithium-ion batteries based on recursive least squares and the extended Kalman filter algorithm is proposed. Finally, to verify the effectiveness of the proposed method, the experimental data of the battery at variable environment temperature is obtained under improved hybrid pulse power characteristic (IHPPC). The results show that the proposed method can estimate the average temperature of lithium-ion batteries in real time. The maximum error of the temperature estimation model after the algorithm convergence is 1.8 ℃, and the average error is only 1 ℃.

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    Expansion Planning of Renewable Energy Power System Considering Flexibility and Economy
    LI Lingfang, CHEN Zhanpeng, HU Yan, TAI Nengling, GAO Mengping, ZHU Tao
    2021, 55 (7):  791-801.  doi: 10.16183/j.cnki.jsjtu.2020.024
    Abstract ( 716 )   HTML ( 15 )   PDF (1623KB) ( 514 )   Save

    The large-scale access to renewable energy such as wind power and photovoltaics brings great uncertainty in power system planning and operation. In order to enhance the ability of high-proportion renewable energy grid to respond to uncertain events and ensure the safe and economic operation, it is necessary to improve the flexibility of the power system. First, based on the perspective of line transmission capacity and safe operation, the flexibility index of the transmission line was defined. Next, considering the economic operation strategy of the system, a multi-objective transmission line planning model based on flexibility and economy was proposed to optimize the flexibility index, investment cost, operating cost, and renewable energy consumption. After that, the NSGAII optimization algorithm was used to solve the model. Finally, the improved Garver-6 and IEEE RTS-24 node systems were taken as examples to analyze the effectiveness of the proposed model. The results show that the planning scheme can improve the transmission capacity of power grids, reduce the probability of renewable energy abandonment, and improve the flexibility and economy of power grid operation.

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    Flexibility Evaluation Method for Power System Based on Clustering of Typical Operating Scenarios
    YOU Guangzeng, TANG Xiangying, HU Yan, TAI Nengling, ZHU Xinchun, LI Lingfang
    2021, 55 (7):  802-813.  doi: 10.16183/j.cnki.jsjtu.2020.012
    Abstract ( 728 )   HTML ( 14 )   PDF (2608KB) ( 548 )   Save

    The development of renewable energy represented by wind, photovoltaic, and hydropower can increase the uncertainty of power systems. In order to ensure the flexible operation of power systems with a high proportion of renewable energy, a power system flexibility evaluation method based on typical operating scenarios was proposed. Through a modified K-means algorithm, the operating scenarios of renewable energy and load were clustered to obtain typical scenarios. The flexibility evaluation indexes were proposed from three perspectives including regional supply and demand balance, regional power flow distribution, and inter-regional transmission capacity. The flexibility evaluation index of each scenario, and the comprehensive evaluation index based on the appearance probability of each scenario were calculated to evaluate the flexibility of the system. Based on the actual historical output data of new energy and the load of a certain region in the south, the flexibility evaluation was performed on a modified IEEE 39 system. The results show that the proposed clustering method and flexibility index can effectively reflect the flexibility of the system.

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    Design of Slip Ring Based on SSP Compensation and Variable Frequency Control
    FENG Xin, FU Zhuang, WANG Kejin, HAO Gaofeng
    2021, 55 (7):  814-825.  doi: 10.16183/j.cnki.jsjtu.2020.093
    Abstract ( 518 )   HTML ( 5 )   PDF (7076KB) ( 417 )   Save

    In order to avoid the disadvantages of the traditional slip ring, such as easy wear and easy accumulation of static electricity, a novel slip ring design method based on series series parallel (SSP) compensation and variable frequency control is proposed. First, the magnetic circuit of the non-contact slip ring is modeled. The leakage inductance and the magnetizing inductance of the loosely coupled transformer, namely the primary side series compensation and secondary side series parallel compensation, are compensated respectively. Next, due to the influence of temperature and other factors, the sensitivity of some components is analyzed, and the relationship between component parameter variation and resonance frequency variation is obtained. After that, a phase difference detection method based on Hanning window fast Fourier transform is proposed, which can avoid the restriction of hardware performance and improve the anti-interference ability. Finally, according to the calculated phase difference and critical quality factor, a variable frequency control method based on zero phase angle is proposed to help the system work at zero phase angle, thereby reducing the loss of reactive power. The simulation results show that when the component parameters change, the proposed method based on SSP compensation and variable frequency control can quickly help the system work in zero phase angle state, and then improve the efficiency of the system. A prototype is designed to verify the proposed method, and the experimental results are basically consistent with the simulation results. Compared with no compensation method, the efficiency of the proposed method is increased by 5%. The research results show that the method proposed has a high robustness.

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    Microfluidic Inertial Switch Capable of Bidirectional Anti-High Overload
    ZHANG Runduo, NIE Weirong, QIU Weixiang
    2021, 55 (7):  826-833.  doi: 10.16183/j.cnki.jsjtu.2020.279
    Abstract ( 655 )   HTML ( 5 )   PDF (10025KB) ( 281 )   Save

    In order to realize the stable application of microfluidic inertial switch in the intelligent ammunition fuze system, a bidirectional anti-high overload microfluidic inertial switch is proposed to solve the problem of switch contact instability caused by the mercury droplet separation under high impact. The structures of snake-shaped buffer channel and three-stage capillary valve are designed based on the principle of capillary force applied to the mercury droplet in microchannel. The force state of the mercury droplets in the contraction type and the expansion type of capillary valves is analyzed. The static threshold model of the mercury droplet in the rectangular channel is established. The user defined function (UDF) is used to apply acceleration load to the finite element simulation of the switch. The simulation analysis suggests that under the action of typical forward service drop load and typical reverse service drop load, the mercury droplets can be restored to its initial state without droplet separation, indicating that the switch has a reliable anti-high overload ability. Two centrifugal experiments are conducted to complete the preparation and injection of tiny mercury droplets. The microfluidic switch prototype is used in the impact test of the Machete drop hammer. The results show that the mercury droplet separation does not occur in the switch under the action of typical forward impact load and typical reverse impact load, which are consistent with the simulation results.

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    Operation Analysis of PandaX-4T Ultra-High Purity Xenon Cryogenic Distillation System for Removal of Krypton
    YAN Rui, WANG Zhou, CUI Xiangyi, JU Yonglin, SHA Haidong, LI Shuaijie, HUANG Peiyao, WANG Xiuli
    2021, 55 (7):  834-841.  doi: 10.16183/j.cnki.jsjtu.2020.180
    Abstract ( 599 )   HTML ( 7 )   PDF (1366KB) ( 359 )   Save

    Based on the McCabe-Thiele (M-T) method and the conservation of mass and energy, the PandaX-4T collaboration group designs an efficient cryogenic distillation system to reduce the mole fraction of krypton in commercial xenon from 5×10-7 to 1×10-14. Since the ultra-high purity xenon cryogenic distillation system has completed the offline purification operation, it is necessary to conduct the corresponding operation analysis. Therefore, the stability and purification performance of the ultra-high purity xenon cryogenic distillation system are studied by analyzing the parameters such as temperature, pressure, flowrate, and mole faction of the product xenon in each operating stage. The PandaX-4T cryogenic distillation system has been operating stably for 1.5 m at a collection efficiency of 99% and a purification rate of 10 kg/h, and has purified 5.75 t of xenon. The experimental data show that the system is stable, safe, and reliable in all stages of operation, and the krypton concentration in product xenon is less than 7.99×10-12. The operation analysis of the PandaX-4T ultra-high purity xenon cryogenic distillation system has a theoretical research value and practical engineering significance, providing very important reference for optimization of distillation operation of the next stage.

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    Simulation and Optimization of Ultra-High Purity Krypton/Xenon Cryogenic Distillation System Based on HYSYS
    SHA Haidong, HUANG Peiyao, WANG Zhou, CUI Xiangyi, JU Yonglin, YAN Rui, LI Shuaijie, WANG Xiuli
    2021, 55 (7):  842-849.  doi: 10.16183/j.cnki.jsjtu.2020.223
    Abstract ( 605 )   HTML ( 7 )   PDF (1065KB) ( 426 )   Save

    To meet the requirements of the low background and high sensitivity of the large-scale dark-matter detector PandaX-4T, nKr/nXe≤1×10 -13 (n is the amount of substance) is required. The ultra-high purity krypton/xenon cryogenic distillation tower was used as an example in this paper. First, the distillation tower and the construction design of the distillation system were briefly introduced. Then, the operation parameters of the distillation tower were simulated and optimized by using HYSYS, and the distributions of the pressure, temperature and Kr concentration in the distillation tower were obtained. After that, the influences of those operational conditions including the feeding point position, the reflux ratio, the feeding flowrate, the heat of the reboiler, the flowrate of the off-gas, and the feeding pressure to the xenon purity of the distillation system were studied, and the optimized operation parameters were proposed. When the column pressure is set at 221 kPa and the reflux radio is set at 145, the krypton content in xenon can be purified from 5×10-7 to 4.1×10-14, which has an important guiding significance for further improvement of the purity of the xenon product of the xenon/krypton cryogenic distillation system.

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    Extraction of Fracture Toughness Parameters by Ring-Notched Small Punch Specimen Using Cohesive Model
    ZHANG Yu, LIU Haiting, WENG Lin, SHEN Yao
    2021, 55 (7):  850-857.  doi: 10.16183/j.cnki.jsjtu.2020.129
    Abstract ( 624 )   HTML ( 6 )   PDF (2128KB) ( 359 )   Save

    The fracture toughness of in-service equipment and irradiation materials can be obtained from the ring-notched small punch specimen. The cohesive model was used to describe the ductile fracture behavior and crack propagation process of T91 steel, and the two parameters of material required by this model were calibrated by using the inverse finite element method. The successful implementation of this method requires that the load-displacement curve in the fracture damage stage is sensitive to the two model parameters, which can be optimized by the geometric design of the specimen and notch. The influence of the ratio of diameter to thickness, the depth of notch, and the presence or absence of prefabricated cracks on parameter sensitivity was studied, and the optimized design of the ring-notched specimen was obtained, based on which, a set of parameters was selected for finite element simulation to obtain the load-displacement curve. This curve was chosen as the target, and the genetic algorithm and the random walk algorithm were used for iterative fitting by using the inverse finite element method to extract the parameters of the cohesive model. The calculated results show that the error between the obtained parameters and the pre-selected parameters is less than 1%, which verifies the sensitivity of the specimen design and the accuracy of the inverse finite element method.

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    Optimization Model of Maintenance and Spare Parts Ordering Policy in Multivariate Degradation System
    YANG Zhiyuan, ZHAO Jianmin, CHENG Zhonghua, GUO Chiming, LI Liying
    2021, 55 (7):  858-867.  doi: 10.16183/j.cnki.jsjtu.2019.221
    Abstract ( 614 )   HTML ( 8 )   PDF (2404KB) ( 307 )   Save

    Aimed at the decision-making problem of condition-based maintenance and spare parts ordering for systems with multiple dependent degradation processes, an optimization model of system maintenance and spare parts ordering policy is developed under the condition of continuously monitoring. First, the Gamma process and Copula function are used to develop the system multivariate degradation model. Then, the system maintenance and spare parts ordering policy based on the control limit strategy is proposed. Considering the influence of system degradation on maintenance cost, the analytical expression of the expected maintenance cost rate under long-term operation conditions is obtained. At the same time, an approximate expression of the expected maintenance cost rate is proposed to simplify the model calculation. The optimal preventive replacement threshold and spare parts ordering threshold of the system are obtained by using the artificial bee colony algorithm under the cost criterion. The case analysis shows that it is necessary to consider degradation in maintenance decision-making. Compared with the existing policy, the comprehensive optimization of preventive replacement and spare parts ordering thresholds can effectively reduce the maintenance cost of the system.

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    Thermal Dynamic Model and Thermal Characteristics of Airships Considering Skin Transmittance
    CHENG Chen, WANG Xiaoliang
    2021, 55 (7):  868-877.  doi: 10.16183/j.cnki.jsjtu.2019.039
    Abstract ( 656 )   HTML ( 10 )   PDF (2071KB) ( 408 )   Save

    Taking stratospheric airship as the research object, considering the transmission characteristics of the airship surface and the absorption rate and emissivity of the inner filling gas to radiation, the thermodynamic equations of the airship surface skin and inner filling gas are deduced. The thermodynamic simulation model of the airship considering the transmittance of the skin is established by using the sub-method, and the thermodynamic characteristics of airship under typical skin materials are analyzed and compared. Through airship shape modeling and surface discretization, the transient thermal characteristics of each unit and internal gas are calculated, and the influence of the mesh division and time step in the simulation model on the calculation results is analyzed. The data verifies the reliability and validity of the established model and its solution method, and the thermal characteristics and the changing laws of airships with different characteristics of skin materials are analyzed and compared.

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    Numerical Simulation of Critical Oil Velocity Required to Completely Remove Water Lump Deposited in Hilly Oil Pipelines
    LI Yansong, DING Dingqian, HAN Dong, LIU Jing, LIANG Yongtu
    2021, 55 (7):  878-890.  doi: 10.16183/j.cnki.jsjtu.2020.020
    Abstract ( 613 )   HTML ( 6 )   PDF (4255KB) ( 334 )   Save

    Removing the trapped water lump from the pipelines by using the hydraulic pigging (HP) method can effectively reduce the attenuation of oil quality. It is of great practical significance to study the critical oil velocity required to completely remove the water lump trapped in hilly oil pipelines. First, the flow patterns of water expelled by oil stream in an upward inclined pipeline are analyzed when the oil velocity in pipelines reachs the critical value required to completely remove the water. It is found that the flow process of the water removed by oil stream belongs to oil-water two phase stratified wavy flow. Next, the numerical model governing the flow of water expelled by oil is established in the bipolar coordinate system based on the flow pattern aforementioned, and the numerical solution method is also proposed. Finally, the numerical model is validated through the comparison of the results calculated by the model with the data from the literature. The flow of water lump expelled by diesel in an upward inclined pipeline is numerically studied, and the characteristics of the oil flow and water lump mobilization during the HP process are analyzed in detail. The results show that the water lump is mainly influenced by gravity pressure drop. The friction pressure drop could be neglected compared to the gravity pressure drop. When the oil velocity in the pipe is small, the water phase near the interface is carried downstream by the oil stream, while that near the pipe wall flows back to the bottom of the pipeline due to gravity. The postion of the minimum velocity in the water phase will shift to the pipe wall with the oil velocity increasing. When the minimum water velocity appears at the pipe wall for the first time, the oil velocity in pipelines can be regarded as the critical oil velocity required to completely remove the water lump in the pipelines.

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    Infrared Multispectral Radiation Temperature Measurement Based on PCA-ELM
    XI Jianhui, JIANG Han, CHEN Bo, FU Li
    2021, 55 (7):  891-898.  doi: 10.16183/j.cnki.jsjtu.2020.027
    Abstract ( 630 )   HTML ( 9 )   PDF (1988KB) ( 389 )   Save

    In the case of unknown target emissivity, an infrared multispectral radiation temperature measurement method based on principal component analysis (PCA) and extreme learning machine (ELM) is established. The nonlinear mathematic model of target temperature and radiance spectrum is analyzed to find a set of initial input vectors, which include sufficient information to estimate temperature. The PCA method is used to extract the independent principle components in input vectors. This method can also reduce the input dimension for neural network. Based on ELM network, the sample data is sufficiently learned to build the target infrared temperature measurement model by PCA-ELM. The effectiveness of the proposed method is verified by using the blackbody and the coating material with unknown emissivity as test target sources.

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    Low-Power Consumption Design and Optimization of New Artificial Anal Sphincter
    YAO Shengjian, YAN Guozheng, WANG Zhiwu, ZHOU Zerun, JIANG Pingping, DING Zifan, HUA Fangfang, ZHAO Kai, HAN Ding
    2021, 55 (7):  899-906.  doi: 10.16183/j.cnki.jsjtu.2020.199
    Abstract ( 605 )   HTML ( 7 )   PDF (5725KB) ( 459 )   Save

    Based on the hardware of the new artificial anal sphincter system, this paper analyzes the power consumption of each module. After low-power consumption design and reasonable setting of the sampling period, the system power consumption is significantly reduced. At the same time, the area under the rectal pressure waveform is used as the standard for judging defecation willingness. Instead of the single-point pressure threshold method, it provides a basis for anal incontinence patients to go to the toilet, and thus improves the accuracy of the rectal perception function. Combining in vitro and in vivo experiments, the low-power consumption of the artificial anal sphincter designed in this paper can extend the working time of the system to 16 d after a single charge. It increases the working time by 230% with a rectal perception accuracy of 96%.

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