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28 September 2023, Volume 57 Issue 9 Previous Issue   
New Type Power System and the Integrated Energy
An Admittance Reshaping Strategy of Three-Phase LCL Grid-Connected Inverter Based on Modified Passive Control
WANG Han, ZHANG Jianwen, SHI Gang, ZHU Miao, CAI Xu
2023, 57 (9):  1105-1113.  doi: 10.16183/j.cnki.jsjtu.2022.120
Abstract ( 85 )   HTML ( 3 )   PDF (3313KB) ( 49 )  

The passivity-based control (PBC) based on energy function has been studied for grid-connected converters to achieve a better performance. However, traditional PBC method relies on the accurate mathematical model of grid-connected inverter. In previous studies on PBC, the effect of digital control delay is rarely considered and the stability under grid impedance uncertainties is not discussed, especially in the capacitive grid or complex weak grid. To address these issues, this paper proposes an improved PBC method to reshape the output admittance for LCL-filtered grid-connected inverters. The system passive region is expanded up to the Nyquist frequency by adding a capacitor current feedback loop which can achieve active damping control of LCL resonant frequency under the wide range of grid impedance changes. The parameter design method is also presented for the proposed PBC control. To verify the correctness of the theoretical analysis, both simulation and experiments are conducted on a 3 kW grid-connected inverter prototype.

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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
2023, 57 (9):  1114-1125.  doi: 10.16183/j.cnki.jsjtu.2022.121
Abstract ( 13 )   HTML ( 3 )   PDF (2373KB) ( 9 )  

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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A Microgrid Energy Management Strategy Considering Carbon Quota Guided Demand Response
JIANG Enyu, CHEN Yu, SHI Zhengjing, WU Zhecheng, LIN Shunfu, LI Dongdong
2023, 57 (9):  1126-1136.  doi: 10.16183/j.cnki.jsjtu.2022.378
Abstract ( 33 )   HTML ( 2 )   PDF (2823KB) ( 14 )  

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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Two-Stage Optimal Configuration of Microgrid Based on Fuzzy Scene Clustering
MI Yang, LI Haipeng, CHEN Boyang, PENG Jianwei, WEI Wei, YAO Yan
2023, 57 (9):  1137-1145.  doi: 10.16183/j.cnki.jsjtu.2022.090
Abstract ( 32 )   HTML ( 4 )   PDF (7524KB) ( 14 )  

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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Optimal Planning of Power Systems with Flexible Resources for High Penetrated Renewable Energy Accommodation
GUO Yongtao, XIANG Yue, LIU Junyong
2023, 57 (9):  1146-1155.  doi: 10.16183/j.cnki.jsjtu.2022.269
Abstract ( 53 )   HTML ( 2 )   PDF (2433KB) ( 34 )  

High penetrated renewable energy has brought great challenges to the flexibility of the power system due to its volatility and intermittency. To improve the capacity of renewable energy accommodation, the flexibility reformation of thermal power units, the construction of gas-fired units, and the electrical energy storage installation are considered as effective solutions. Thus, an optimization model for power system planning scheme considering multi-type flexible resources with their different output characteristics is established. The simulation results on a modified IEEE 24-bus power system and 12-node natural gas system demonstrate the effectiveness of the proposed model. In addition, the applicability of different flexible resource planning schemes is comprehensively evaluated from the perspectives of economy, accommodation capacity, and carbon reduction, so as to meet the different planning goals.

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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
2023, 57 (9):  1156-1164.  doi: 10.16183/j.cnki.jsjtu.2022.135
Abstract ( 32 )   HTML ( 2 )   PDF (4403KB) ( 17 )  

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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Resilience Evaluation and Enhancement Strategy of Distribution Network Considering Impact of Seismic Attack on Transportation Networks
YAN Wenting, YANG Long, LI Changcheng, LUO Wei
2023, 57 (9):  1165-1175.  doi: 10.16183/j.cnki.jsjtu.2022.152
Abstract ( 90 )   HTML ( 2 )   PDF (2248KB) ( 102 )  

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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Electronic Information and Electrical Engineering
Optical Feature Analysis and Diagnosis of Partial Discharge in C4F7N/CO2 Based on Multispectral Array
LI Ze, QIAN Yong, ZANG Yiming, ZHOU Xiaoli, SHENG Gehao, JIANG Xiuchen
2023, 57 (9):  1176-1185.  doi: 10.16183/j.cnki.jsjtu.2022.299
Abstract ( 38 )   HTML ( 2 )   PDF (8904KB) ( 31 )  

Optical detection of partial discharge (PD) is an important way to reflect the insulation status of equipment. C4F7N/CO2 gas mixture is one of the most potential substitutes for SF6 at present, but there is a lack of research on its optical PD characteristics and diagnostic methods. In this paper, a PD multispectral array detection platform that can collect 7 characteristic bands is constructed, and 4 kinds of PD defects are produced. The similarities and differences of the PD multispectral characteristics in phase distribution, energy distribution, and feature stacking map under the conditions of 5 different ratios of C4F7N/CO2 gas mixture and pure SF6 gas are analyzed. Finally, a novel method of PD diagnosis based on multispectral features (MF) and k-nearest neighbors (KNN) is proposed. The experimental results show that the fault recognition accuracy in pure SF6 can reach 96.2%. The recognition rate of C4F7N/CO2 gas mixture is above 88%, and the highest accuracy rate is 91.1%. This method has a guiding significance for the PD diagnosis of environmentally friendly gas-insulated equipment, and provides a new route for traditional PD detection and diagnosis.

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Evaluation of Thermal Insulation Performance of EB-PVD YSZ Thermal Barrier Coatings by Phosphorescence Lifetime Online Measurement
LIU Zhenghong, YU Yali, CHENG Weilun, LI Muzhi, YANG Lixia, ZHAO Xiaofeng, PENG Di, MOU Rende, LIU Delin
2023, 57 (9):  1186-1195.  doi: 10.16183/j.cnki.jsjtu.2022.252
Abstract ( 28 )   HTML ( 2 )   PDF (10690KB) ( 72 )  

Precise measurement of the thermal insulation performance of thermal barrier coatings (TBCs) under the thermal gradient environment is important for the design and development of TBCs. A phosphorescent sensor TBC which contains an Eu doped yttria-stabilized zirconia (YSZ:Eu) surface layer, a YSZ intermediate layer, and a YSZ:Dy bottom layer, is designed and prepared by electron beam physical vapor deposition (EB-PVD). Based on the thermal quenching characteristics of phosphorescence signal, the surface temperature of the YSZ coating and the interface temperature of the bond-coat/YSZ layer are measured online in a temperature gradient environment, and the real thermal insulation effect of the EB-PVD YSZ thermal barrier coating is evaluated. The results show that the EB-PVD YSZ coating with a thickness of 113 μm can achieve an average temperature decrease of 66.5 ℃. The average thermal conductivity of the coating is (0.87±0.15) W/(m·K) in the temperature range between 400 and 700 ℃, which is slightly lower than the value (0.95±0.02) W/(m·K) obtained by using the traditional laser flash method. The above results validate the reliability of online phosphorescence temperature measurement technique, and provide an effective method to monitor the thermal insulation effect of TBCs in real time.

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Design of a Rapid Thermal Cycling System for Real-Time Fluorescent PCR with Zone Temperature Control
CHEN Erdong, GAO Zihang, WANG Kundong, LEI Huaming
2023, 57 (9):  1196-1202.  doi: 10.16183/j.cnki.jsjtu.2022.361
Abstract ( 12 )   HTML ( 3 )   PDF (7673KB) ( 7 )  

The thermal cycling system is the key component of the real-time fluorescent polymerase chain reaction (PCR) instrument, which determines the nucleic acid detection efficiency and result accuracy. Aiming at the problems that the thermal cycle of the traditional PCR detection system takes a long time and the temperature control is complicated, a real-time fluorescent PCR thermal cycle system with partition temperature control is designed, including the hardware circuit and mechanical structure of the thermal cycle system. The rapid thermal cycling is achieved by switching the test solution between different constant temperature zones, and the temperature is controlled using an incremental proportional integral derivative (PID) algorithm, with a control precision of ±0.1 ℃. Using Fluent software to establish heat transfer model, the thermal delay phenomenon of the test solution was analyzed to predict the temperature variation pattern of the test solution. A prototype is built for testing and verification, and the heating and cooling rates of the test liquid are 3.8 ℃/s and 4.4 ℃/s. It is verified that the proposed PCR thermal cycling system can effectively improve the detection efficiency.

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A Structured Pruning Method Integrating Characteristics of MobileNetV3
LIU Yu, LEI Xuemei
2023, 57 (9):  1203-1213.  doi: 10.16183/j.cnki.jsjtu.2022.077
Abstract ( 141 )   HTML ( 4 )   PDF (11611KB) ( 74 )  

Due to its huge amount of calculation and memory occupation, the traditional deep neural network is difficult to be deployed to embedded platform. Therefore, lightweight models have been developing rapidly. Among them, the lightweight architecture MobileNet proposed by Google has been widely used. To improve the performance, the model of MobileNet has developed from MobileNetV1 to MobileNetV3. However, the model has become more complex and its scale continues to expand, which is difficult to give full play to the advantages of lightweight model. To reduce the difficulty of deploying MobileNetV3 on embedded platform while maintaining its performance, a structured pruning method integrating the characteristics of MobileNetV3 is proposed to prune the lightweight model MobileNetV3-Large to obtain a more compact lightweight model. First, the model is trained by sparse regularization to obtain a sparse network model. Then, the product of the sparse value of convolution layer and scale factor of batch normalization layer is used to identify the redundant filter, which is structurally pruned, and experiment is conducted on CIFAR-10 and CIFAR-100 datasets. The results show that the proposed compression method can effectively compress the model parameters, and the compressed model can still ensure a good performance. While the accuracy remains unchanged, the number of parameters on CIFAR-10 in the model is reduced by 44.5% and calculation amount is reduced by 40%.

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Aeronautics and Astronautics
Arc Attachment Characteristics of Carbon Fiber Reinforced Thermoplastic Materials
XIE Minqi, XIAO Cien, BIAN Jiapeng, LIU Yakun, FAN Yin, CHEN Xiuhua, LIU Libo
2023, 57 (9):  1214-1220.  doi: 10.16183/j.cnki.jsjtu.2022.146
Abstract ( 32 )   HTML ( 3 )   PDF (14040KB) ( 92 )  

As a promising structural material, carbon fiber reinforced thermoplastic (CFRTP) has been gradually applied on aircrafts. The lightning arc adhesion characteristics of CFRTP, however, are still unclear. Therefore, the arc adhesion characteristics of CFRTP were studied by simulating the lightning test method. Based on the finite element method, the effect of CFRTP on spatial electric field was analyzed and compared with that of metal materials. It is found that for the structure containing both CFRTP and metal materials, CFRTP is possible to be attached by the lightning discharging channel, but the probability is lower than that of the metal material by 22.5%. In the process of lightning arc adhesion, single upward leader and multiple upward leaders appear on the surface of CFRTP, resulting in the corresponding single or multiple arc attachment points. Simultaneous adhesion of lightning arc on both CFRTP and metal material also occurs. The spatial electric distribution obtained by simulation is consistent with the experimental results. This paper can provide the basis for the lightning characteristics and damage response of CFRTP.

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Experimental Study of Influence of Different Parameters on Flow Field Structures Around an Airfoil Covered with Rough Ice
ZHENG Chengyi, DU Xuzhi, DONG Qiaotian, YANG Zhigang, XIONG Bing, XU Yi, WU Linghao, JIN Zheyan
2023, 57 (9):  1221-1230.  doi: 10.16183/j.cnki.jsjtu.2022.149
Abstract ( 21 )   HTML ( 2 )   PDF (8438KB) ( 37 )  

Rough ice can change the leading edge of airfoil and affect the aerodynamic characteristics. Studying the influence of rough ice caused by supercooled water droplets can provide reference for anti-icing design of aircrafts. A detailed experimental study was conducted to measure the flow field structure of an airfoil model with rough ice in a low-speed wind tunnel by using particle image velocimetry. The parameters include Reynolds number, roughness of rough ice, and angle of attack. The results show that with the increase of Reynolds number, the range and value of spanwise vorticity at the wake of the airfoil with ice increased, while the normalized Reynolds stress decreased slightly. The presence of rough ice reduced the airflow velocity near the airfoil, increased the vorticity of wake, and seriously affected the shear stress distribution. Compared with the clean airfoil, the rough ice caused the air flow to separate earlier and the velocity in the separation bubble fluctuated more violently.

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