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Table of Content

    28 December 2022, Volume 56 Issue 12 Previous Issue    Next Issue
    New Type Power System and the Integrated Energy
    Differentiated Allocation Model of Renewable Energy Green Certificates for New-Type Power System
    ZHANG Shuo, LI Wei, LI Yingzi, LIU Qiang, ZENG Ming
    2022, 56 (12):  1561-1571.  doi: 10.16183/j.cnki.jsjtu.2022.150
    Abstract ( 1238 )   HTML ( 816 )   PDF (1436KB) ( 705 )   Save

    In order to achieve China’s “30·60” decarbonization goal, the green and low-carbon transformation of the energy system is the fundamental support; the construction of new-type power system is the key step, and the green certificate is the important voucher to reflect the green value of renewable energy. Currently, the distribution mechanism of green certificates in China is oversimplified, which neither effectively measures the variability of green values generated by different types of renewable energy, nor balances the coordinated development of renewable energy. Therefore, to differentiate the exchange mechanism of green certificates by different types of renewable energy power in this paper, an evaluation index system is established, which describes the difference between green certificates, considering the comprehensive value of renewable energy, and an evaluation model is built with the criteria importance by using the intercriteria correlation (CRITIC) method, the entropy weight method, and the technique for order preference by similarity to an ideal solution (TOPSIS) method. Under the development scenario of peaking carbon emissions before 2030, the impact of the differentiated distribution model on the green incomes of centralized photovoltaic distributed photovoltaic power, onshore wind power, and offshore wind power is analyzed. Moreover, the development plan of renewable energy is modified in consideration of the effect of the differentiated distribution model, and policy suggestions on green certificates are proposed accordingly. The results show that the differentiated distribution model of green certificates is practical to provide corresponding decision-making support to the construction and improvement of green certificates trading mechanism in China.

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    Analysis of Sub/Super-Synchronous Oscillation of Direct-Drive Offshore Wind Power Grid-Connected System via VSC-HVDC
    ZHANG Zhiqiang, LI Qiutong, YU Hao, CHEN Honglin, SUN Haishun
    2022, 56 (12):  1572-1583.  doi: 10.16183/j.cnki.jsjtu.2021.434
    Abstract ( 773 )   HTML ( 86 )   PDF (10512KB) ( 424 )   Save

    The system of offshore direct-drive wind farm connected to the power grid via voltage source converter based high voltage direct current (VSC-HVDC) transmission consists of several converters, which have different time scale control loops and complex dynamic characteristics. Based on an example case with two direct-drive wind farms and VSC-HVDC transmission system, the sub/super-synchronous oscillation modes of the system and its relationship with current control loops are studied by state space analysis. The research shows that there are three dominant modes related to the current control of the converter in the system, which are the oscillation mode between wind farms and the offshore converter station, the mode between the offshore wind farms, and the mode between the onshore converter station and the alternating current (AC) system. The modes at the wind farm side are decoupled from the mode between the onshore converter station and the AC system. The relevant control parameters of the converters and the operating conditions have an important impact on the stability of the three modes. The oscillation caused by the single dominant mode may spread to the other side of VSC-HVDC, which means it is necessary to identify the root cause of oscillation in order to design the suppression strategy. The research results is of guidance to the understanding of the dynamic characteristics of offshore wind power grid-connected systems via VSC-HVDC, parameter design, and oscillation suppression.

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    A Sensing Method Based of Floating Photovoltaic Grids to Sudden Changes in Marine Weather
    JIANG Haoyu, WANG Peilun, GE Quanbo, XU Jinqiang, LUO Peng, YAO Gang
    2022, 56 (12):  1584-1597.  doi: 10.16183/j.cnki.jsjtu.2021.526
    Abstract ( 740 )   HTML ( 202 )   PDF (8866KB) ( 439 )   Save

    Currently, the application of floating photovoltaics in the ocean is mainly restricted by the cost of submarine cables and special buoys. It will show a high degree of applicability if the energy is consumed by the unmanned management systems on ocean farms and in other scenarios. The grid system formed by the floating photovoltaics can satisfy the early warning requirements of the sudden weather changes on ocean farms. Due to the strong follow-up of the photovoltaic output model to random weather changes, based on the spatial-temporal correlation analysis of large-area photovoltaics, hardware, distance, time delay, and weather, a similar power station fusion estimation relationship is established. Based on the long short-term memory (LSTM) algorithm, the ultra-short-term prediction value of the time sequence tracking of similar power stations can be used to estimate the early warning of the status of target similar power stations. The city-scale data was used to verify the feasibility of the proposed idea, which shows that the framework can complement traditional research deficiencies.

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    A Multi-Scenario Integrated Flexible Planning Method for Microgrid
    PAN Xianxian, CHEN Tingwei, XU Zhiheng, WANG Tianlun, ZHANG Junxiao
    2022, 56 (12):  1598-1607.  doi: 10.16183/j.cnki.jsjtu.2021.402
    Abstract ( 415 )   HTML ( 130 )   PDF (1484KB) ( 330 )   Save

    In order to improve the economy of microgrid construction and operation, and meet the personalized demand for reliability of various types of microgrids, an integrated flexible planning method for microgrid is proposed to adapt to multiple scenarios. Based on the judgment results of type and composition, a two-layer model including capacity planning and grid planning is established. The lower-level capacity planning takes the minimum operation cost of micro-source construction as the goal and adopts the mixed integer optimization algorithm to solve it. The upper layer grid planning takes the minimum cost of network construction and operation as the goal, and uses the particle swarm optimization algorithm to solve it. A closed-loop integrated planning system consisting of judgment, capacity planning, and grid planning is formed. The system can meet the personalized reliability requirements of different microgrids by flexibly adjusting the independent operation duration constraints and the load outage attention parameters. The example shows that the proposed method can effectively reduce the construction and operation cost of microgrid, and has a good adaptability to different types and components and different reliability requirements.

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    Torque Ripple Reduction Method of Switched Reluctance Motor Based on Five-Level Converter
    LING Hui, DU Qinjun, FENG Han, PANG Hao, YANG Shuxin, LUO Yonggang
    2022, 56 (12):  1608-1618.  doi: 10.16183/j.cnki.jsjtu.2022.124
    Abstract ( 476 )   HTML ( 92 )   PDF (6694KB) ( 301 )   Save

    Aimed at the problem of large torque ripple and low efficiency caused by the poor current tracking effect of switched reluctance motor (SRM), a torque ripple reduction method of switched reluctance motor based on a five-level converter is proposed. A novel five-level converter with A and C phases or B and D phases sharing the same bridge arm is designed. Compared with the traditional converter, the control is more flexible and the cost is lower. According to the nonlinear model of SRM, the conduction region is reclassified, and the phase output torque with a large inductance change rate is preferred to avoid excessive peak current at the beginning of commutation. Aimed at the problem of poor winding current tracking ability when the speed and load conditions change greatly, the direct instantaneous torque control (DITC) method based on the five-level converter is proposed, and the DITC conduction rules at low and high speeds are designed. According to the current speed, the torque error, and the rotor position, the appropriate conduction mode is selected to make sure that the motor can run stably at a low speed and the current can track the required value in time at a high speed, so as to realize the reduction of torque ripple. The simulation and experimental results show that compared with the traditional DITC, the control strategy can reduce the torque and current ripple in a wide speed range and improve the dynamic characteristic of the torque.

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    Aerodynamic Effect of Deflection Angle of Trailing Edge Flap on Vertical Axis Wind Turbine with Different Airfoils
    DAI Mengyi, ZHANG Zhihao, TU Jiahuang, HAN Zhaolong, ZHOU Dai, ZHU Hongbo
    2022, 56 (12):  1619-1629.  doi: 10.16183/j.cnki.jsjtu.2022.110
    Abstract ( 497 )   HTML ( 130 )   PDF (5904KB) ( 401 )   Save

    Low power efficiency is a critical factor that restricts marketization development of the vertical axis wind turbine (VAWT). The proposal of the trailing edge flap can change flow structure on blade surface, so as to improve the aerodynamic performance of VAWT. At present, the variation law of aerodynamic performance of different airfoil VAWT with trailing edge flaps is not clear. Based on the computational fluid dynamics (CFD) method and the shear stress transport (SST) model, a numerical simulation of 3 H-type VAWTs with different airfoils (NACA0018, NACA0021, and NACA0024) with separated trailing edge flap is conducted. It is found that the results of the validation case are in good agreement with experimental results, which verifies the reliability of this method. Afterwards, 3 basic airfoils and 5 groups of flap deflection angle (-16°, -8°, 0°, 8°, and 16°) parameters are selected to explore the difference in the aerodynamic performance of VAWTs. The results indicate that the positive flap deflection angle in the upwind region can effectively improve blade moment coefficient, and the negative flap deflection angle in the downwind region has a beneficial effect. For the negative flap, the degree of wind energy utilization affected by deflection is positively correlated with airfoil thickness, while for the positive flap, the opposite is true. The research results of this paper can provide an effective reference for application of trailing edge flaps of vertical axis wind turbines.

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    Electronic Information and Electrical Engineering
    Online Estimation of Supercapacitor State of Charge Based on Nonlinear Observer
    DU Yushi, JU Changjiang, YANG Genke
    2022, 56 (12):  1630-1637.  doi: 10.16183/j.cnki.jsjtu.2021.210
    Abstract ( 441 )   HTML ( 8 )   PDF (1181KB) ( 334 )   Save

    Supercapacitors have the advantages of fast charging and discharging, high power density, and long life, which are widely used in energy storage systems for new energy vehicles. Reliable operation of the system requires the acquisition of its remaining electricity, which is to estimate its state of charge (SOC). Relying on the equivalent analog circuit model of a single supercapacitor, this paper establishes a state-space model of the capacitor second-order nonlinear system with the multi-capacitor terminal voltage in the model as the state, the capacitor input current as the control input, and the capacitor output voltage as the observation output, and contains the leakage current caused by the self-discharge phenomenon. In order to improve the simulation accuracy, different model parameters were identified to characterize the charging and discharging conditions. In this paper, a nonlinear observer algorithm is used to obtain the internal state of the model to realize the estimation of SOC. The results of the charging and discharging experiment show that considering the leakage factor and establishing the charging and discharging model with different parameters, the dynamic characteristics of the supercapacitor can be better simulated, and the nonlinear observer algorithm has a stable tracking ability.

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    K-means Hybrid Iterative Clustering Based on Memory Transfer Sailfish Optimization
    HUANG He, XIONG Wu, WU Kun, WANG Huifeng, RU Feng, WANG Jun
    2022, 56 (12):  1638-1648.  doi: 10.16183/j.cnki.jsjtu.2021.292
    Abstract ( 477 )   HTML ( 4 )   PDF (3095KB) ( 317 )   Save

    Aimed at the problem that the existing K-means clustering (KMC) algorithm is greatly affected by initialization, and the randomly generated clustering center can easily make the clustering result fall into local optimum and stop iterating, resulting in low clustering accuracy and poor robustness, a K-means hybrid iterative clustering algorithm based on memory transfer sailfish optimization (MTSFO-HIKMC) is proposed. First, learning from the existing improvement ideas, the maximum and minimum distance product is introduced to initialize the KMC cluster center, to avoid the uncertainty caused by random initialization. At the same time, in the iterative process, the current optimal solution is made to locally perform adaptive memory transfer correction to solve the problem of poor global optimization ability and insufficient search accuracy caused by the single search path of the sailfish algorithm. Using the Iris, Seeds, CMC and Wine international standard data sets, the MTSFO-HIKMC, the sailfish optimized K-means hybrid iterative clustering (SFO-KMC) algorithm, the introduction of the improved Moth-to-fire K-means cross iterative clustering (IMFO-KMC) algorithm, the KMC algorithm, and the fuzzy C-means (FCM) algorithm are compared and tested. From the obtained convergence curves and performance indicators, it can be seen that the MTSFO-HIKMC algorithm proposed in this paper has a faster convergence speed than IMFO-KMC. Compared with the IMFO-KMC algorithm, the dimensional space has a higher search accuracy. Compared with the KMC algorithm and FCM, it has a higher search accuracy. Compared with the SFO-KMC algorithm, its convergence speed and search accuracy are significantly improved, especially in high-dimensional data sets.

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    A Circuit Simulation Model of 1S1R for 3D Phase-Change Memory
    ZHANG Guangming, LEI Yu, CHEN Houpeng, YU Qiuyao, SONG Zhitang
    2022, 56 (12):  1649-1657.  doi: 10.16183/j.cnki.jsjtu.2021.522
    Abstract ( 639 )   HTML ( 15 )   PDF (2939KB) ( 414 )   Save

    The 1S1R storage unit of 3D phase-change memory is composed of ovonic threshold switch selector (OTS) in series with the phase change memory (PCM) device. In order to solve the problems of the current OTS and PCM circuit simulation models, such as not able to accurately simulate the electrical and physical characteristics of devices, and not suitable for confined PCM, a 1S1R spice model based on Verilog-A is proposed. The model simulates the electrical characteristics of OTS and the changes of current, temperature, melting proportion, crystallization proportion and amorphous proportion in the crystallization, melting and quenching of the PCM. The model has a good convergence and fast simulation speed. The simulation results are consistent with the actual test results of the device. Compared with the traditional model, the simulation and integration of confined PCM melting process, crystal nonlinearity, melting resistivity stability and subthreshold nonlinearity, and bidirectional switching characteristics of OTS are realized. The relationship between OTS subthreshold nonlinear parameter and read voltage window is analyzed. It is found that the read window reaches its maximum when OTS threshold current is approximately equal to PCM threshold current. The results of DC simulation of 1S1R cell and transient simulation of array are displayed, providing the basis for circuit design and simulation of 3D phase-change memory.

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    A Self-Localization Algorithm with Adaptive and Dynamic Observation Period for Mobile Underwater Acoustic Networks
    GAO Jingjie, WANG Wei, SHEN Xiaohong
    2022, 56 (12):  1658-1665.  doi: 10.16183/j.cnki.jsjtu.2021.193
    Abstract ( 376 )   HTML ( 3 )   PDF (1288KB) ( 304 )   Save

    In order to resolve the conflicts between the communication traffic and the localization accuracy, a self-localization algorithm with adaptive and dynamic observation period for mobile underwater acoustic networks (MUANs) was proposed to improve the localization performance. First, an adaptive and dynamic observation period selection scheme was designed, which could generate a non-uniform observation period vector according to the residual change. Then, based on the non-uniform observation period vector, a self-localization algorithm was proposed, which could precisely predict the trajectory of each mobile node in the network. The simulation results show that the proposed algorithm, which could balance the tradeoff between the localization accuracy and the communication cost, is more suitable for the underwater environment.

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    A Few-Shots OFDM Target Augmented Identification Method Based on Transfer Learning
    TANG Zeyu, ZOU Xiaohu, LI Pengfei, ZHANG Wei, YU Jiaqi, ZHAO Yaodong
    2022, 56 (12):  1666-1674.  doi: 10.16183/j.cnki.jsjtu.2022.041
    Abstract ( 550 )   HTML ( 11 )   PDF (1895KB) ( 349 )   Save

    Under the few-shots condition caused by non-cooperative scenes, robust extraction of communication emitter features and accurate identification of targets are the difficulties and hotspots of current research. Aimed at the problem of emitter identification under the few-shots condition of orthogonal frequency division multiplexing (OFDM) signals, this paper proposes a non-cooperative target identification method based on phase/time domain flipping data augmentation and source domain instance-based transfer learning. The data set is expanded by different domain flipping data augmentation methods, and the improved residual network is applied to achieve the purpose of promoting the identification rate of the OFDM emitter. Then, transfer learning is introduced to strengthen the generalization ability of the identification model. The experimental results show that the data augmentation method can significantly improve the OFDM emitter identification rate under the few-shots condition. Furthermore, the transfer learning method accelerates the convergence speed, slightly increases the recognition rate, and improves robustness of the model.

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    Microstructure and Properties of CoCrFeMnNiMox High-Entropy Alloy Coating by Laser Cladding
    LIU Hao, SUN Shifeng, LI Xiaojia, HAO Jingbin, YANG Haifeng
    2022, 56 (12):  1675-1687.  doi: 10.16183/j.cnki.jsjtu.2021.201
    Abstract ( 519 )   HTML ( 5 )   PDF (39366KB) ( 356 )   Save

    45 steel has the problems of low wear resistance and poor corrosion resistance. CoCrFeMnNiMox (x=0.00, 0.25, 0.50, 0.75, 1.00) high-entropy alloy coating was prepared on 45 steel by laser cladding. The influence of Mo on the microstructure and properties of coating were explored in detail. The results show that the CoCrFeMnNiMox high-entropy alloy coating is composed of a single face-centered cubic (FCC)solid-solution phase. The microstructure of the Mo-containing coating is a typical dendritic and interdendritic structure, which is caused by the heterogeneous nucleation of the molten pool during the solidification process. The microhardness of the coating increases with the increase of x, and the maximum microhardness of the Mo1.00 coating is 2.391 GPa. Quantitative calculations show that solution strengthening is the main reason for the increase of microhardness. With the increase of Mo mass fraction, the wear mechanism evolves from adhesive wear to abrasive wear and oxidative wear. The Mo1.00 coating has the lowest volume wear rate (0.68×10-4 mm3/(N·m)). The influence of the passivation process on the corrosion resistance of coating was analyzed based on the point defect model theory. The addition of the Mo element increases the dehydration rate of the passivation behavior of coating, which makes the oxide layer thicker, and thereby improving the corrosion resistance of coating. The corrosion mechanism of coatings is intergranular corrosion. Mo0.75 coating has the smallest self-corrosion current density and the most positive self-corrosion potential, which are 3.69×10-6 A/cm2 and -0.432 V, respectively.

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    Naval Architecture, Ocean and Civil Engineering
    Dynamic Multi-Objective Optimization Inverse Prediction of Excavation-Induced Tunnel Displacement
    HE Wei, SUN Honglei, TAO Yuanqin, CAI Yuanqiang
    2022, 56 (12):  1688-1699.  doi: 10.16183/j.cnki.jsjtu.2021.282
    Abstract ( 424 )   HTML ( 15 )   PDF (3483KB) ( 336 )   Save

    Control of the disturbed displacement of adjacent tunnel during excavation is a significant issue for design and construction. Based on the multi-objective optimization method, the multi-type monitoring data in the excavation of the excavation are integrated, the key soil parameters are inverted and identified, and the time effect of the tunnel displacement is quantified and corrected. A dynamic multi-objective optimization method with adaptive infill criterion (DMO-AIC) is proposed to improve the updating efficiency of dynamic surrogate models. The proposed method takes into account the computational redundancy of dynamic surrogate models in engineering optimization, and designs an adaptive point-adding discrimination strategy, which can autonomously identify invalid updates of surrogate models on the optimization path. The results show that the proposed DMO-AIC significantly reduces the invocations of the black-box model during optimization while ensuring the good search performance and the convergence speed of the algorithm. The improved computational efficiency of DMO-AIC is helpful for the application of dynamic surrogate models in engineering optimization. The results of the virtual numerical example show that DMO-AIC can predict and update multiple model responses during excavation, such as wall deflections and tunnel displacements. The engineering practice of Shanghai Bund 596 excavation indicates that the time effect is properly updated, and the staged vertical displacements of the adjacent tunnel are accurately predicted.

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    Fracture Damage Characteristics of Rock Under Pre-Peak and Post-Peak Cyclic Loading Condition
    TANG Jianhui, CHEN Xudong, BAI Yin
    2022, 56 (12):  1700-1709.  doi: 10.16183/j.cnki.jsjtu.2021.119
    Abstract ( 422 )   HTML ( 12 )   PDF (10992KB) ( 285 )   Save

    In the process of rock excavation, cyclic loading may occur before or after the peak value. In order to obtain the fracture damage evolution characteristics of rock under the pre-peak and the post-peak cyclic loading condition, the fracture tests of three-point bending granite beams were conducted by using the digital image correlation method and the acoustic emission technology. Based on the secant modulus, the acoustic emission energy and effective crack length, the rock fracture damage indexes DE, DAE, and DL were constructed respectively, and the rock fracture damage process was quantitatively analyzed. The results show that the damage index of the rock sample has an obvious rate effect. At the same number of cycles, as the loading rate increases, the damage index decreases. For the pre-peak cyclic loading condition, the fracture process of rock from elastic stage to elastic-plastic stage can be well reflected by DE. Under the condition of post-peak cyclic loading, DL can better represent the fracture damage process of rock from step up to continuous failure.

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    Risk Assessment for Shield Tunneling Beneath Buildings Based on Interval Improved TOPSIS Method and FAHP Method
    CHEN Renpeng, WANG Zhiteng, WU Huaina, LIU Yuan, MENG Fanyan
    2022, 56 (12):  1710-1719.  doi: 10.16183/j.cnki.jsjtu.2021.018
    Abstract ( 376 )   HTML ( 13 )   PDF (1682KB) ( 305 )   Save

    In order to evaluate the impact of shield tunnel construction on adjacent buildings, a method based on the fuzzy analytic hierarchy process (FAHP) and the interval number improvement technique for order preference by similarity to ideal solution (TOPSIS) is proposed. A risk assessment system based on soil properties, building factors, tunnel factors, shield tunneling parameters, and other factors is established after investigation. The FAHP is used to determine the weight of factors based on expert scoring. Based on the traditional TOPSIS method, 6 typical samples are selected according to the factor grading standard to determine the non-uniform risk rating criteria. For the first time, the interval improved TOPSIS method is applied to the risk assessment of shield tunneling beneath buildings. The engineering situation can be better represented by the interval number. Compared with traditional risk assessment methods, this method is more accurate, less affected by subjective factors, and more objective. The proposed method has been used to evaluate the risk of a certain masonry building, and the result is consistent with the actual situation, which proves its effectiveness of. Thus, the proposed method can provide reference for risk assessment of similar projects.

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