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    Stepwise Inertial Intelligent Control of Wind Power for Frequency Regulation Based on Stacked Denoising Autoencoder and Deep Neural Network
    WANG Yalun, ZHOU Tao, CHEN Zhong, WANG Yi, QUAN Hao
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1477-1491.   DOI: 10.16183/j.cnki.jsjtu.2022.157
    Accepted: 10 March 2023

    Abstract1617)   HTML10)    PDF (10551KB)(126)      

    Stepwise inertial control (SIC) provides a step-increase of power after load fluctuation, which can effectively prevent system frequency decline and ensure the safety of grid frequency. However, in the power recovery stage, secondary frequency drop (SFD) is easy to occur. Therefore, it is necessary to optimize SIC to obtain a better frequency regulation effect. The traditional method has the disadvantages of high calculation dimension and long consuming time, which is difficult to meet the requirements of providing the optimal control effect in different scenarios. In order to realize the optimal stepwise inertial fast control of wind power frequency regulation in load disturbance events, this paper introduces the deep learning algorithm and proposes a stepwise inertial intelligent control of wind power for frequency regulation based on stacked denoising autoencoder(SDAE) and deep neural network(DNN). First, sparrow search algorithm (SSA) is used to obtain the optimal parameters, and SDAE is used to extract the data features efficiently. Then, DNN is used to learn the data features, and the accelerated adaptive moment estimation is introduced to optimize the network parameters to improve the global optimal parameters of the network. Finally, the stepwise inertial online control of wind power frequency regulation after disturbance event is realized according to SDAE-DNN. The simulation analysis is conducted for a single wind turbine and a wind farm in the IEEE 30-bus test system. Compared with the results obtained by the traditional method, shallow BP neural network and original DNN network, it is found that the proposed network structure has a better prediction accuracy and generalization ability, and the proposed method can achieve a great effect of stepwise inertia frequency regulation.

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    Optimization Design of New Bionic Propeller
    WU Chunxiao, LU Yu, LIU Shewen, GU Zhuhao, SHAO Siyu, SHAO Wu, LI Chuang
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1421-1431.   DOI: 10.16183/j.cnki.jsjtu.2022.174
    Accepted: 27 October 2022

    Abstract1614)   HTML17)    PDF (10709KB)(239)      

    A novel method for optimal design of hydrodynamic performance of bionic propeller with a deformable leading edge is proposed. Based on the bionics principle and method of parameterized modeling, the fore-fin concave-convex structure of humpback whales is applied to the propeller leading edge, the leading edge in the propeller to meet flow region according to the exponential decay curve and the standard sine curve smooth leading edge for similar humpback fins protuberant structure of concave and convex deformation, and the leading edge of concave and convex bionic propeller. The hydrodynamic performance, the cavitation performance, and the noise performance of the exponential decay bionic propeller and the sinusoidal function bionic propeller were simulated respectively. The propeller with a better performance is selected, and the simulation based design (SBD) technology is introduced into the optimization design of the new bionic propeller. The parameters controlling the shape of the exponential attenuation curve of the guide edge deformation are taken as optimization design variables, the torque of the parent propeller is taken as the constraint condition, the open water efficiency is selected as the objective function, and the optimization algorithm of Sobol and T-Search is adopted. A bionic propeller optimization system based on the exponential decay curve is constructed. The results show that the application of the concave and convex structure of the humpback whale fore-fin to the guide edge of the propeller improves the cavitation performance and noise performance of the propeller, but the improvement of the open water performance of the propeller is not particularly significant. It is verified that the hydrodynamic performance optimization design method of the bionic propeller established in this paper is effective and reliable, which provides a certain theoretical basis and technical guidance for the performance numerical calculation and configuration optimization design of the bionic propeller.

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    Analysis of Fluid-Structure Coupling Energy Transfer Characteristics Slender Structure with Variable Cross-Section at Low Reynolds Number
    DENG Xiubing, YU Yuemin, PANG Xiyuan
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1400-1409.   DOI: 10.16183/j.cnki.jsjtu.2022.133
    Accepted: 17 February 2023

    Abstract1610)   HTML11)    PDF (18587KB)(115)      

    The wavy deformed cross-section cylindrical structure has excellent properties of drag reduction in fluid flow, but the flow-induced vibration characteristics of flexible structure with such variable cross-section are still unclear. In this paper, based on the high-performance spectral element method, a fluid-structure coupled mechanistic model and a numerical algorithm for slender structures are established. The wake characteristics, structural dynamic responses, energy transfers, and spanwise variations of vortex shedding frequencies are discussed. The numerical simulation results show that slender structure with the wavy-deformed cross-section can greatly suppress the vortex-induced vibration response at an appropriate cross-section disturbance wave height, and the special vortex structure formed on both sides of the wavy-shaped slender structure can stabilize the flow around the shear layer and elongate the vortex formation length, thereby reducing the fluid-structure coupling effect between the wake structure and the slender structure, and suppressing the vortex-induced vibration response.

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    Wake Field Characteristics of Non-Ducted and Ducted Propellers in Large-Angle Oblique Flow
    ZHANG Qin, WANG Xinyu, WANG Zhicheng, WANG Tianyuan
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1432-1441.   DOI: 10.16183/j.cnki.jsjtu.2022.159
    Accepted: 09 December 2022

    Abstract1603)   HTML10)    PDF (18498KB)(129)      

    In order to explore the wake characteristics of non-ducted and ducted propellers in oblique inflow with a large drift angle, based on the delayed detached eddy simulation, a numerical simulation of non-ducted and ducted propellers in oblique inflow is conducted with an advance coefficient (J=0.4) and a large drift angle (β=45°, 60°). It is found that the deflection degree of the non-ducted propeller wake is higher than that of the ducted propeller. However, the overall distribution area of the wake vortex behind the ducted propeller is kinked. The wake field in the oblique flow shows its complexity, and the evolution process of vortices on the windward side differs from that on the leeward side. The above characteristic of the non-ducted propeller is more prominent. At the same time, the leading edge of the nozzle on the leeward side will produce local shedding vortices and transmit to the downstream due to flow separation. Part of the kinetic energy of the ducted propeller is converted into the nozzle thrust, which makes the turbulence kinetic energy of the wake lower than that of the non-ducted propeller. This phenomenon is more evident with the increase in the drift angle. Compared with the non-ducted propeller, the ducted propeller can maintain a better handling stability in large-angle oblique flow. This paper analyzes the influence of large-angle oblique inflow on the non-ducted and ducted propellers from the perspective of wake field characteristics and explores the theoretical basis for the ducted propeller to maintain a better handling stability in oblique flow.

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    Optimization of Wind Turbine Vortex Generator Based on Back Propagation Neural Network
    XIA Yunsong, TAN Jianfeng, HAN Shui, GAO Jin’e
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1492-1500.   DOI: 10.16183/j.cnki.jsjtu.2022.169
    Accepted: 28 March 2023

    Abstract1573)   HTML11)    PDF (9995KB)(99)      

    The optimal Latin hypercube experimental design method is used to refine the vortex generator parameters, determine the test scheme, simulate and calculate the thrust and torque of the wind turbine, and obtain the experimental data. Based on the back propagation (BP) neural network, the aerodynamic performance model of the wind turbine vortex generator optimized by genetic algorithm is constructed. The reliability of the aerodynamic performance model is verified by calculating the error and root mean square of the predicted and simulated values of the aerodynamic performance model. Coupling the fish swarm algorithm and the aerodynamic performance model of the wind turbine vortex generator, an optimization method of the wind turbine vortex generator is established, and the height, length, and installation angle of the vortex generator are solved iteratively to realize the optimization of the vortex generator. The results show that compared with the original vortex generator scheme, the flow separation of the wind turbine blade section optimized by the vortex generator is effectively restrained and delayed, the surface fluid separation phenomenon is improved, the power of the wind turbine is increased by 1.711%, and the thrust of the wind turbine is decreased by 0.875%.

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    Experimental Investigation of Dynamic Response of Pile-Supported Wharf in Liquefiable Ground Under Wave Action
    BI Jianwei, SU Lei, XIE Libo, ZHANG Yu, LING Xianzhang
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1442-1454.   DOI: 10.16183/j.cnki.jsjtu.2022.163
    Accepted: 10 November 2022

    Abstract1558)   HTML9)    PDF (8259KB)(176)      

    Pile-supported wharf (PSW) is widely used in the deep-water port engineering construction, most of which are located in liquefiable ground. The effect of wave action on the working performance of PSW in liquefiable ground cannot be ignored, but few studies have been reported. This study performs the wave flume test of PSW in liquefiable ground considering the soil-structure-wave interaction. This test really reproduces the operating condition of PSW, and explores the internal response difference of wharf structure under wave. The influence of wave height on dynamic response of the PSW system is discussed systematically. The result shows that the acceleration and displacement of the PSW deck gradually increase first and finally remain relatively stable with the increase of wave action. The hydrodynamic pressure and deformation of each pile in pile group are obviously different, and the response variation is related to the pile position. The pore pressure of the soil layer in the free field and around the pile decreases with the increase of depth, and the existence of the pile group can reduce the pore pressure in the soil layer around the pile, and increase the acceleration of the soil layer. The effect of wave height on the soil layer decreases with the increase of depth. The above results can provide reference for the similar PSW test under wave and the support for the design and wave protection of PSW.

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    Robust Optimization of Power Grid Investment Decision-Making Considering Regional Development Stage Uncertainties
    HUANG Wandi, ZHANG Shenxi, CHENG Haozhong, CHEN Dan, ZHAI Xiaomeng, WU Shuang
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1455-1464.   DOI: 10.16183/j.cnki.jsjtu.2022.053
    Abstract1538)   HTML13)    PDF (2782KB)(65)      

    Aimed at the problem of uncertainties in the regional development stage and the difficulties in quantifying regional investment demand in different development stages, a robust optimization method for power grid investment decision-making considering regional development stage uncertainties is proposed to promise the matching degree between power grid investment decisions and development needs, and to improve the ability of decision-making results to deal with portfolio risks and uncertainties in regional development stage. First, investment risk constraints are constructed based on the modern portfolio theory. Then, a box uncertainty set is used to characterize uncertainties in regional development stage, and a robust optimization model for power grid investment decision-making considering uncertainties in development stage is established. In the optimization model, the outer minimization problem is used to solve the uncertain variables in regional development stage in the worst scenario, while inner maximization problem is used to obtain the decision-making plan that can maximize investment return in the worst scenario. Furthermore, according to the strong duality theory, the double-layer optimization model is transformed into a single-layer model that can be solved directly, and the big-M method is used to solve the model proposed. Finally, an actual example of 13 cities in an eastern coastal province verifies the applicability and effectiveness of the power grid investment decision-making model.

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    An Improved NLC and Capacitor Voltage Control Method for Medium-/Low-Voltage MMCs
    ZHANG Wei, HAN Junfei, ZHONG Ming, WANG Yuqiang
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1465-1476.   DOI: 10.16183/j.cnki.jsjtu.2022.172
    Accepted: 27 March 2023

    Abstract1436)   HTML12)    PDF (2806KB)(93)      

    The modular multilevel converter (MMC) suffers from low output level and high harmonic distortion in medium-/low-voltage applications such as direct current (DC) distribution networks. In addition, the capacitor voltage of MMC is coupled with DC bus voltage in the traditional modulation method, leading to large fluctuations of capacitor voltages and deviation from the rated value under DC bus voltage margin. In order to solve the problems above, this paper proposes an improved nearest level control method, which can increase the output level of medium-/low-voltage MMCs by introducing a step wave correction. Based on the proposed modulation method, a capacitor voltage feedback control is thus proposed to limit the range of capacitor voltage fluctuations and improve equipment safety. The effectiveness of the proposed method is verified by MATLAB/Simulink simulation and real-time digital simulation system hardware-in-the-loop test.

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    Simulation Study of Reentry Dynamics of a Deep-Water Drilling Riser System Based on Model Predictive Control
    ZHANG Chenyu, MENG Shuai
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1389-1399.   DOI: 10.16183/j.cnki.jsjtu.2022.235
    Accepted: 09 December 2022

    Abstract1321)   HTML25)    PDF (2622KB)(178)      

    A marine drilling riser at normal operation condition is required to disconnect the lower marine riser package (LMRP) and blow-out preventer (BOP) in case of severe weather. When the weather gets fine, it must reconnect the LMRP and the BOP. This process is called riser reentry. Marine drilling operations have been driven into extreme deep-waters characterized by severe weather which inevitably leads to a much higher incidence of disconnection. In addition, it requires to accomplish the reentry in a fast way owing to the capricious ocean environment. This study tries to develop a novel reentry control system based on model predictive control (MPC). First, the transverse governing equation of the hanging-off riser system with an end-mass is established based on the modified Hamilton’s principle. The optimization function and constraints in MPC are designed by use of the riser prediction model and the target location. A nonlinear disturbance observer is established for compensation of the model uncertainties and ocean environment disturbances. Finally, simulations are conducted after introducing the dynamic position system (DPS). The riser dynamics employing MPC are compared with that when adopting proportional-integral-derivative (PID) controller. It has found that the drilling riser system based on MPC has a higher response speed, which can complete the reentry process in a faster and more stable manner. It can handle the hydrodynamic force model uncertainties well and has a good robustness for current velocity disturbances. As the flexibility of the riser system is notably enhanced with the significant increase of aspect ratio, the higher-order mode of the flexible hanging-off riser can be triggered in the fast reentry process subjected to the excitations of the mother vessel and ocean environment.

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    Multi-Objective Optimization of Electric Vehicle Spare Capacity Based on User Wishes
    SHAO Ping, YANG Zhile, LI Kang, ZHU Xiaodong
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1501-1511.   DOI: 10.16183/j.cnki.jsjtu.2022.131
    Accepted: 05 July 2023

    Abstract902)   HTML8)    PDF (5565KB)(98)      

    Due to the considerable number and the characteristics of energy storage, it is possible for electric vehicles (EVs) to participate in the operation and regulation of power system to provide reserve service. In view of this, a multi-objective optimal scheduling model is established based on the wishes of electric vehicle users, with the objectives of the economic benefits of electricity collectors, microgrid power fluctuations and user satisfaction. Considering the uncertainty of load demand, the optimal scheduling analysis of multi-time scale scenes with the day-ahead time scale and the intra-day real-time correction time scale is conducted. The mainstream multi-objective intelligent optimization algorithm NSGA-III algorithm is adopted in the solution method, and the NSGA-II and MOEA/D algorithms are used for comparison. The optimal dispatching scheme is selected through comparative experiments and scenarios where EVs provide spare capacity are analyzed. The simulation results verify the feasibility and effectiveness of the proposed model.

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    Dynamic Characteristics of Two-Dimensional Structures Slamming Under Free Fall Condition
    SUN Zhe, SUI Xupeng, KOROBKIN Alexander, DENG Yanzeng, ZHANG Guiyong, ZONG Zhi, JIANG Yichen
    Journal of Shanghai Jiao Tong University    2023, 57 (11): 1410-1420.   DOI: 10.16183/j.cnki.jsjtu.2022.189
    Accepted: 21 March 2023

    Abstract832)   HTML11)    PDF (1402KB)(149)      

    The slamming process of two-dimensional structures under free fall condition with arbitrary symmetrical shapes is investigated by combining various analytical models for slamming and the precise integration method in the time domain. By closely analyzing the mathematical expression of analytical models, the total slamming force acting on the body can be decomposed into two terms which are dependent on the velocity and the acceleration respectively. The developed model proposed in this paper is validated against the results from experiments and other numerical methods. Moreover, it is found that if the gravity of body is ignored, which is a reasonable assumption for situations such as structures with light weight or large entry velocity, the maximum acceleration (or the peak slamming force) for a free fall body will always occur at the certain penetration depth for a particular shape and mass, regardless of the initial slamming velocity.

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    A Microgrid Energy Management Strategy Considering Carbon Quota Guided Demand Response
    JIANG Enyu, CHEN Yu, SHI Zhengjing, WU Zhecheng, LIN Shunfu, LI Dongdong
    Journal of Shanghai Jiao Tong University    2023, 57 (9): 1126-1136.   DOI: 10.16183/j.cnki.jsjtu.2022.378
    Accepted: 23 May 2023

    Abstract725)   HTML15)    PDF (2823KB)(97)      

    In order to reduce the forecast output error caused by the randomness and volatility of renewable energy in microgrid operation, a microgrid energy management strategy considering carbon quota guided demand response is proposed. A two-layer model predictive control (MPC) energy management model is constructed. The upper layer guides electric vehicles to participate in the demand response of microgrid by constructing a carbon emission quota mechanism to realize the economic operation of microgrid and reduce carbon emissions. The lower layer uses the model predictive control rolling optimization and the power fluctuation caused by the prediction error of renewable energy is suppressed by the short time scale model predictive control. The results of calculation analysis show that the proposed energy management strategy can effectively guide electric vehicles or other controllable loads to participate in demand response and realize low-carbon economic dispatch and stable operation of microgrid.

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    Resilience Evaluation and Enhancement Strategy of Distribution Network Considering Impact of Seismic Attack on Transportation Networks
    YAN Wenting, YANG Long, LI Changcheng, LUO Wei
    Journal of Shanghai Jiao Tong University    2023, 57 (9): 1165-1175.   DOI: 10.16183/j.cnki.jsjtu.2022.152
    Accepted: 14 February 2023

    Abstract724)   HTML14)    PDF (2248KB)(202)      

    Serious earthquake disasters not only cause power outages in distribution network, but also destroy transportation networks, which hinders the transportation of resources for restoration of distribution network and slows down the restoration. This paper proposes an improved resilience evaluation method and a resilience enhancement strategy of distribution network considering the effects of seismic attack on transportation networks. First, a seismic attack model is established to describe the relation between earthquake disasters and failure probability of transportation-distribution networks based on peak ground acceleration. The impact of earthquake disasters on transportation-distribution networks is quantified, and the failure scenarios are generated. Then, a resilience evaluation index is proposed by introducing the waiting time for road repair of emergency repair teams. Afterwards, a bi-level optimization model for distribution network restoration considering the fault line repair, the road repair, and the emergency resource scheduling is established and solved. The upper layer aims at the minimum power loss load, while the lower layer takes the minimum waiting time of the repair team as the goal. Finally, case studies on a coupling example of a 12-node transportation network and an IEEE 33-node distribution network verify the feasibility of the improved resilience index and the effectiveness of the proposed method. The results show that the resilience index considering seismic attack on transportation networks is accurate, and the restoration strategy can effectively enhance the resilience of distribution network in earthquake disasters.

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    A Two-Stage Distributionally Robust Economic Dispatch Model Under the Coordination of Inter-Provincial and Intra-Provincial Bi-Level Market
    CHEN Yi, WANG Han, XU Xiaoyuan, HU Youlin, YAN Zheng, ZENG Dan, FENG Kai
    Journal of Shanghai Jiao Tong University    2023, 57 (9): 1114-1125.   DOI: 10.16183/j.cnki.jsjtu.2022.121
    Abstract682)   HTML18)    PDF (2373KB)(80)      

    To promote the optimal allocation of resources across the country, China is actively developing inter-provincial electricity transactions, and will gradually form an inter-provincial and intra-provincial electricity market operation mode. In this context, a two-stage day-ahead, and intraday economic dispatch framework considering inter-provincial and intra-provincial bi-level market coordinated operation is proposed. In the day-ahead dispatch stage, an inter-provincial and intra-provincial bi-level economic dispatch model is constructed. In the intraday dispatch stage, an economic dispatch model considering the forecast error of source-load is constructed. To further deal with the influence of the uncertainty of source-load forecast on economic dispatch, a two-stage day-ahead and intraday distributionally robust economic dispatch model and its solution method are proposed, realizing the economic dispatch under random scene ambiguity set. Finally, a multi-sending ends and multi-receiving ends interconnected test system is constructed using IEEE 39-bus and 118-bus systems. The effectiveness of the proposed model and method is verified by simulation.

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    Two-Stage Optimal Configuration of Microgrid Based on Fuzzy Scene Clustering
    MI Yang, LI Haipeng, CHEN Boyang, PENG Jianwei, WEI Wei, YAO Yan
    Journal of Shanghai Jiao Tong University    2023, 57 (9): 1137-1145.   DOI: 10.16183/j.cnki.jsjtu.2022.090
    Accepted: 21 April 2023

    Abstract664)   HTML10)    PDF (7524KB)(100)      

    Aimed at the impact of extreme weather on the stable operation of microgrid, an optimal configuration strategy of microgrid based on fuzzy scene clustering is proposed. Using historical weather data, a fuzzy scene clustering method is used to deal with the problem of new energy output fluctuations caused by random weather on the source side, and a robust optimization model is established on the load side to deal with load fluctuations within a certain range. Using scenes of 8 760 hours in a year, typical scenes and extreme scenes are obtained by distinguishing the unique membership characteristics of fuzzy scene clusters. Considering the impact of extreme scenarios on the optimal configuration of the microgrid, a two-stage robust model with the smallest comprehensive cost is established, which is decomposed by the column and constraint method, and is finally solved iteratively by Cplex solver. The effectiveness and feasibility of the proposed optimal configuration strategy are verified by simulation analysis.

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    An Adaptive Additional Control Strategy for Suppressing Low-Frequency Grid Oscillations in Doubly-Fed Wind Farms
    LIU Xinyu, WANG Sen, ZENG Long, YUAN Shaoheng, HAO Zhenghang, LU Xinyan
    Journal of Shanghai Jiao Tong University    2023, 57 (9): 1156-1164.   DOI: 10.16183/j.cnki.jsjtu.2022.135
    Accepted: 26 April 2023

    Abstract660)   HTML9)    PDF (4403KB)(126)      

    Aiming at the problem of weakly or negatively damped low-frequency oscillations caused by cross-zone transmission of electricity from large wind farms, this paper proposes a fast terminal sliding-mode additional damping controller based on the Lyapunov stability theory. By investigating the flexible power regulation characteristics and the capability of dynamic frequency response to damping regulation of doubly-fed wind turbines (DFIG), a rotor magnetic chain controller is designed according to the relationship between the applied voltage and magnetic chain of DFIG rotor and the sliding mode variable structure control method. When low-frequency oscillations occur in the system, the desired magnetic chain value will deviate from the actual magnetic chain value. The additional damping controller outputs an adaptive control signal for the rotor-side power control link to increase the active output of the wind farm and suppress low-frequency oscillations in the system. A simulation model of the wind power grid-connected system is established in MATLAB/Simulink for off-line simulations, and a real-time simulation experiment of a large wind farm cross-zone transmission model based on real time digital simulation system is conducted. The results of both off-line and real-time simulations show that when low-frequency oscillations occur in the system, the proposed control method can quickly regulate the active power emitted by the DFIG and enhance the damping level of the system, which is effective in suppressing low-frequency oscillations in the system.

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    Cost Sharing Mechanisms of Pumped Storage Stations in the New-Type Power System: Review and Prospect
    LIU Fei, CHE Yanying, TIAN Xu, XU Decao, ZHOU Huijie, LI Zhiyi
    Journal of Shanghai Jiao Tong University    2023, 57 (7): 757-768.   DOI: 10.16183/j.cnki.jsjtu.2021.516
    Accepted: 14 February 2023

    Abstract588)   HTML44)    PDF (2464KB)(417)      

    Driven by the carbon peaking and carbon neutrality goals, the power system is transforming to the new structure which is dominated by renewable energy and is facing a new supply-demand balance situation. Pumped storage, as the most mature energy storage technology at present, can provide flexible resources with different time scales to ensure the safety of the power system and promote the consumption of renewable energy. However, the operation strategy and cost sharing mechanism of the pumped storage station (PSS) are not clear, which hinders its further development under the new situation. In this context, the technical characteristics and functions of PSS are sorted out first. Then, the investment cost model is established from the perspective of the whole life cycle. After that, the evolution path of pricing mechanism and cost sharing mode are described in view of the different stages of electricity market development, providing a feasible scheme for the marketization of PSS. Finally, the future development of PSS is summarized and prospected.

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    UConvTrans:A Dual-Flow Cardiac Image Segmentation Network by Global and Local Information Integration
    LI Qing, HUANGFU Yubin, LI Jiangyun, YANG Zhifang, CHEN Peng, WANG Zihan
    Journal of Shanghai Jiao Tong University    2023, 57 (5): 570-581.   DOI: 10.16183/j.cnki.jsjtu.2022.088
    Accepted: 16 September 2022

    Abstract499)   HTML31)    PDF (9362KB)(446)      

    Cardiac magnetic resonance image (MRI) segmentation has the features such as there is a lot of noise, the target areas are indistinguishable from the background, and the shape of the right ventricle is irregular. Although convolution operations are good at extracting local features, the U-shaped convolutional neural networks (CNN) structure hardly models long-distance dependency between pixels and can not achieve ideal segmentation results on cardiac MRI. To solve these problems, UConvTrans is proposed with a dual-flow U-shaped network by global and local information integration. First, the network applies the CNN branch to extract local features and capture global representations by Transformer branch, which retains local detailed features and suppresses the interference of noise and background features in cardiac MRI. Next, the bidirectional fusion module is proposed to fuse the features extracted by CNN and the Transformer with each other, enhancing the feature expression capability and improving the segmentation accuracy of the right ventricle. Besides, the parameters of network can be set flexibly because the transformer structure in the proposed method does not require pre-trained weights. The proposed method also strikes a better balance between precision and efficiency, which is evaluated on the MICCAI 2017 ACDC dataset. The results show that the network outperforms U-Net by 1.13% average dice coefficient while the parameter amount and the floating point operations are only 10% and 8% of the U-Net. Finally, the proposed method achieves a dice coefficient of 92.42% for the right ventricle, 91.64% for the myocardium, and 95.06% for the left ventricle respectively and wins the first place in the myocardium and left ventricle on test set.

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    Robot Skill Learning Based on Dynamic Motion Primitives and Adaptive Control
    ZHANG Wenan, GAO Weizhan, LIU Andong
    Journal of Shanghai Jiao Tong University    2023, 57 (3): 354-365.   DOI: 10.16183/j.cnki.jsjtu.2021.379
    Accepted: 07 December 2022

    Abstract468)   HTML175)    PDF (12357KB)(365)      

    A novel robot skill learning method using dynamic movement primitive (DMP) and adaptive control is proposed. The existing DMP method learns actions from a single teaching trajectory, and its Gaussian basis function distribution mode is fixed, which is not suitable for multiple movement trajectories with different characteristics. Therefore, the Gaussian mixture model (GMM) and Gaussian mixture regression are introduced into DMP to enable the robot to learn skills from multi-teaching trajectory. Moreover, radial basis function neural network (RBFNN) is introduced into DMP to establish the RBF-DMP method, which is able to learn the central position and weight of Gaussian basis through gradient descent and improves the accuracy of skill modeling. Furthermore, an adaptive neural network controller is designed to control the learned actions of the manipulator in redemonstration. Finally, experiments on Franka Emika Panda manipulator prove the effectiveness of the proposed method.

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    Multi-Physics Field Coupling Simulation of Induction Leveling Process
    LIU Xuyang, CAI Changru, ZHAO Yixi, JU Liyang
    Journal of Shanghai Jiao Tong University    2023, 57 (3): 253-263.   DOI: 10.16183/j.cnki.jsjtu.2021.312
    Accepted: 11 January 2022

    Abstract462)   HTML4267)    PDF (9849KB)(382)      

    The electromagnetic induction leveling method has the characteristics of high efficiency and easy operation. It has a good application prospect in the thin plate leveling process. Based on the fixed inline coil induction leveling process used by the shipyard, this research uses COMSOL Multiphysics to establish a three-dimensional electromagnetic-thermal-mechanical coupling induction leveling finite element model. The model inputs the temperature-dependent physical properties as the material properties of the AH36 steel plate, and takes the residual stress and welding deformation of the butt weldment as the initial state. The method of sequential coupling is used to calculate the changes of electromagnetic field, temperature field, and structure field during the leveling process. The two-way coupling relationship between the temperature field and the electromagnetic field is verified and the deformation of the welded part after leveling is obtained. Through the self-built induction leveling experiment platform, the accuracy and effectiveness of the finite element model are verified.

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