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power system and Green Energy Conference (PSGEC)

作者： Yayao Zhang Min Cheng Meng Zhan Jiawei Yu Yihua Zhu Mingkang Wu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China Yunnan Power Grid China State Key Laboratory of HVDC Electric Power Research Institute China Southern Power Grid China National Energy Power Grid Technology R&D Centre Electric Power Research Institute China Southern Power Grid China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Electric Power Research Institute China Southern Power Grid China

ISBN: (数字)9798350365573

ISBN: (纸本)9798350365580

Transient synchronous stability of renewable grid- tied systems is of paramount importance. Most of previous studies focused on the grid-tied converter in the low voltage ride through (LVRT) during-fault stage and performed stability analysis based on the belief that if the system has (or has no) a stable equilibrium point in the during-fault stage, the system will be stable (or unstable). Therefore, it has been broadly accepted that the existence and/or stability of equilibrium point in the during-fault stage is necessary. However, the whole LVRT contains four different stages and the during-fault stage is only one among them. The transient synchronous stability of whole system should be determined by the initial state in the late post-fault stage and the attraction basin of its equilibrium point. The late post-fault stage is essential for stability and all four stages are important. Clearly treating the during-fault stage as the whole LVRT stages makes the nonlinear switched dynamics problem be greatly simplified and, certainly, is incomplete. In order to clarify this point, this paper analyzes the influence of existence (or nonexistence) of equilibrium point in the during-fault stage on the transient synchronous stability of permanent magnet synchronous generator grid-tied system. We can find that the existence of an equilibrium point in the during-fault stage is only a sufficient condition, rather than a necessary condition. The theoretical analysis is also verified in the hardware-in-the-loop experiment Therefore, a large number of previous studies and results on the transient synchronous stability of renewable grid-tied systems are incomplete and questionable.

关键词： Sufficient conditions Stability criteria Switches Voltage power system stability Synchronous generators Permanent magnets Nonlinear dynamical systems Transient analysis Magnetic switching

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Interfacial Delamination Mechanism of Thermal Barrier Coatings with Real Microstructure Considering Gradient Thermal and Growth Stresses Based on the Fracture Phase Field

SSRN

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SSRN 2023年

作者： Xiao, Yiqi Liu, Zhiyuan Zhu, W. Peng, Xiaomin Hunan Provincial Key Laboratory of Vehicle Power and Transmission System Department of Mechanical Engineering Hunan Institute of Engineering Xiangtan411104 China Hunan Province Engineering Laboratory of Wind Power Operation Maintenance and Testing Technology Hunan Institute of Engineering Xiangtan411104 China School of Materials Science and Engineering Central South University of Forestry and Technology Hunan Changsha410004 China Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education School of Materials Science and Engineering Xiangtan University Hunan Xiangtan411105 China

The interface of atmospheric plasma spray (APS) thermal barrier coatings (TBCs) is highly irregular and rough, while their microstructure is porous and extremely uneven. This complexity leads to intricate patterns during the growth of thermally grown oxide (TGO), the distribution and evolution of the generated stress, as well as the initiation and expansion of cracks. Along these lines, in this work, a phase-field theory considering both the thermal gradient stress and TGO growth was established to thoroughly investigate the interface oxidation cracking in TBCs. More specifically, a two-dimensional geometric model of APS TBCs was established, incorporating real interface morphology and microstructure. Numerical simulations and experiments were also conducted to study the temperature and stress distribution, as well as the underlying mechanism of interface cracking during the service of TBCs. The results indicated that at high temperatures, the bottom temperature of the TC layer with a porosity of 3.1% and a thickness of 200 μm was approximately 5 °C lower than that of the TC layer without porosity. The maximum tensile stress occurred in the peak region near the interface, serving as the primary driving force for crack initiation and propagation near the interface, with opposite shear stress directions being developed at the interface between the peaks or valleys. The stress distribution near the interface in the model considering the real microstructure was similar to the simplified model without porosity, but the stress fluctuation range was greater. the inter-lamella cracks (Type A) in the TC near the peaks initiated earliest, followed by the creation of inter-lamella cracks at other locations, accompanied by the appearance of lamella-fracture cracks (Type B), inter-lamella to interfacial cracks (Type C), inter-lamella to TGO cracks (Type D), and internal TGO cracks (Type E). The coalescence of all these types of cracks will ultimately lead to coating failure. © 2

关键词： Cracks

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Design of Intelligent Lock Based on Face Recognition

Design of Intelligent Lock Based on Face Recognition

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Telecommunications, Optics and Computer Science (TOCS), IEEE Conference on

作者： Hui Li Lei Zhu Shijie Sun Ke Xie Jiabing Wang Dong Liang Hunan Provincial Key Laboratory of Grids Operation and Control on Multi-Power Sources Area Shaoyang China Shaoyang University Shaoyang China Shaoyang China Shaoyang University Shaoyang China

ISBN: (纸本)9781665470544

Aiming at the problems of weak anti-theft effect and the single function of anti-theft system, the paper designs intelligent lock based on face recognition, which combined with wireless transmission, image recognition, environmental detection and other technologies, in order to achieve remote real-time image transmission, mobile phone remote control, face recognition, environmental detection and other functions.

关键词： Wireless communication Bluetooth Face recognition Mobile phones Smart homes Real-time systems Safety

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Modeling of Doubly Fed Wind power Generation system and Simulation Study on Grid-Connection Stability

Modeling of Doubly Fed Wind Power Generation System and Simu...

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Intelligent power and systems (ICIPS), International Conference on

作者： Jingyue Zhang Jie Zhang Yufeng Hu Yuanhong Lu Libin Huang Yanjun Zhao Haiping Guo State Key Laboratory of HVDC Electric Power Research Institute China Southern Power Grid Guangzhou 510663 China Southern Power Grid Guangzhou China National Energy Power Grid Technology R&D Centre Guangzhou 510663 China Southern Power Grid Guangzhou China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou 510663 China Southern Power Grid Guangzhou China CSG Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid Guangzhou 510663 China Southern Power Grid Guangzhou China National Energy Power Grid Technology R&D Centre Guangzhou 510663 Guangzhou China

ISBN: (数字)9798331532765

ISBN: (纸本)9798331532772

Addressing the stability challenges posed by the unpredictability and intermittent nature of wind power output during grid integration, and aiming to enhance the understanding of factors influencing grid stability upon wind power system connection and to implement efficient control measures, a grid- connected model of a doubly fed induction generator (DFIG) was established utilizing a customized version of the RTRES (Real-Time power system Simulation) software, specifically designed for emerging power systems and aligned with wind farm realities. Stability simulations for grid connection were conducted under both voltage regulation mode and reactive power regulation mode across a range of wind speeds, revealing distinct technical behaviors. The findings suggest that the generator's terminal voltage, terminal current, active power, reactive power, and rotor speed exhibit strong correlations with variations in wind speed, and that all parameters are capable of stabilizing following initial disturbances.

关键词： Reactive power Wind speed Rotors power system stability Wind power generation Stability analysis Software Regulation Wind turbines Voltage control

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Dynamic Security Evaluation Method for power systems Considering Cascading Failures

Dynamic Security Evaluation Method for Power Systems Conside...

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IEEE Conference on Energy Internet and Energy system Integration (EI2)

作者： Ren Liu Xingye Xu Wei Du Kaishun Xiahou Yihua Zhu Dongxu Chang Hengdao Guo CSG Key Laboratory for Power System Simulation Electric Power Research Institute of China Southern Power Grid Guangzhou China School of Electric power engineering South China University of Technology Guangzhou China State Key Laboratory of HVDC Electric Power Research Institute of China Southern Power Grid Guangzhou China National Energy Power Grid Technology R&D Centre China Southern Power Grid Guangzhou China Guangdong Provincial Key Laboratory of China Southern Power Grid Intelligent Operation and Control for New Energy Power System Guangzhou China

With the increasing level of informatization and interconnection in the electric power system, the risk of external attacks on power systems is increasing. In response to the drawbacks of traditional static security assessment methods, this paper establishes two security metrics, which are voltage and power flow amplitude deviation security metric and power flow entropy security metric. Based on these security metrics, a dynamic security evaluation model that considers cascading failure is proposed. Simulation results demonstrate that the proposed security metrics can effectively reflect the security of cascading failure propagation, thereby providing valuable insights for decision-making by power system operators.

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Optimization Study on the control Strategy of DC Line Fault Recovery for Yongren-Funing HVDC

Optimization Study on the Control Strategy of DC Line Fault ...

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IEEE Conference on Energy Internet and Energy system Integration (EI2)

作者： Yukun Zhu Libin Huang Shuyong Li Yihua Zhu Yantao Song Ren Liu State Key Laboratory of HVDC China Southern Power Grid Electric Power Research Institute Guangzhou China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou China CSG Key Laboratory for Power System Simulation China Southern Power Grid Electric Power Research Institute Guangzhou China XJ Electric Co Ltd Xuchang China

The ±500kV Yongren-Funing HVDC transmission project is the first HVDC project whose sending and receiving ends are both located in the same province. When DC line fault happened under the condition of inter-communication fault between the pole control systems of the rectifier and inverter stations, the HVDC system cannot be blocked because of the frequent repeating actions of the DC line fault recovery in the inverter station. In order to solve the problem, an optimal control strategy of direct blocking HVDC system was proposed to solve the above issue. The optimization control strategy was verified by RTDS simulation. The simulation results showed that the proposed optimization control strategy of the DC line fault recovery could solve the above problems effectively. The proposed strategy has already been implemented on site permanently, which has great significance for the HVDC/UHVDC transmission projects in operation currently.

关键词： HVDC transmission Simulation Capacitors Rectifiers Optimal control system integration Inverters

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Research on hybrid real-time simulation interface of RTDS digital and physical model 9

Research on hybrid real-time simulation interface of RTDS di...

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9th China International Conference on Electricity Distribution, CICED 2021

作者： Cai, Haiqing Guo, Qi Su, Mingzhang Liu, Shiping Wu, Wencong Huang, Libin Electric Power Research Institute China Southern Power Grid State Key Laboratory of HVDC China National Energy Power Grid Technology R&D Centre Guangzhou510663 China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou510663 China CSG Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid Guangzhou510663 China Electric Power Research Institute of State Grid Jiangxi Electric Power Company Nanchang330096 China

ISBN: (纸本)9781728192291

Digital real-time simulation of physical mixing can connect renewable energy and new energy storage micro-grid physical systems to real-time simulation systems for research and testing. This paper selects ITM interface algorithm to implement digital physical hybrid real-time simulation of energy system. Through its digital-to-analog interface with external photovoltaic equipment to form a digital physical closed loop system. A hardware-in-the-loop simulation platform for photovoltaic grid-connected system is designed. In this paper, the characteristics of photovoltaic grid-connected systems are studied using a digital-physical hybrid hardware-in-the-loop simulation method. Multidimensional tests such as photovoltaic inverter function and dynamic performance tests and microgrid stability tests are performed, to verify the accuracy and stability of the digital-analog hybrid real-time simulation interface. The simulation provide an economical, stable and accurate test platform for future new energy grid-connected equipment testing. © 2021 IEEE.

关键词： Hardware-in-the-loop simulation

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Optimized functional design and simulation study of the fault line selection devices for non-solidly earthed network based on RTDS 9

Optimized functional design and simulation study of the faul...

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9th China International Conference on Electricity Distribution, CICED 2021

作者： Haiqing, Cai Qi, Guo Zhida, Huang Shiping, Liu Wencong, Wu Jiang, Yu Libin, Huang Zebing, Shi Shuyong, Li Electric Power Research Institute China Southern Power Grid State Key Laboratory of HVDC China National Energy Power Grid Technology R&D Centre Guangzhou510663 China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou510663 China CSG Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid Guangzhou510663 China Electric Power Research Institute of State Grid Jiangxi Electric Power Company Nanchang330096 China CSG Power Dispatch Control Center Guangzhou510663 China

ISBN: (纸本)9781728192291

The action accuracy of the fault line selection device is of great significance for ensuring the safe operation of the power system and personal safety. In view of the current imperfect function and the low accuracy of the small current grounding line selection device, the function of line selection of the device is further optimally designed and studied, and the post-acceleration and wheel-cutting functions are put forward and realized. The RTDS simulation model of non-solidly earthed network is established and connected with the actual grounding line selection device to form a closed-loop real-time simulation testing system. By setting up various test items, different types of ground fault test of non-solidly earthed net-work are carried out. The results of simulation show the accuracy of the line selection function, which provides important technical guidance for the implementation of the fault line selection device. © 2021 IEEE.

关键词： Electric grounding

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Research on Transforming Effect and Calculation Method of MMC Converter on AC / DC Harmonics

Research on Transforming Effect and Calculation Method of MM...

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2021 IEEE Sustainable power and Energy Conference, iSPEC 2021

作者： Cui, Liu Peng, Guangqiang He, Jingsong Wu, Jiyang Mao, Chizu Jiao, Ning Electric Power Research Institute China Southern Power Grid State Key Laboratory of Hvdc GuangZhou China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System GuangZhou China Csg Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid GuangZhou China Maintenance Test Center Ehv Power Transmission Company Guangzhou China Csg Key Laboratory for Dc Transmission Equipment State Evaluation and Fault Diagnosis GuangZhou China Sichuan University College of Electrical Engineering and Information Technology Chengdu China

ISBN: (纸本)9781665414395

Modular multilevel converter (MMC) is currently the most concerned voltage source converter topology in the field of flexible direct current transmission (VSC-HVDC). Due to its non-linear characteristics, harmonic components will inevitably be generated in AC and DC systems, which may affect the operation of equipment and system, cause protection equipment to malfunction, and cause interference to neighboring communications. The MMC converter is a non-linear device, which can be considered as an amplifying modulator with voltage and current conversion functions. The AC and DC networks are coupled to each other through the MMC converter to generate dynamic harmonic interaction. In recent years, harmonic instability problems have appeared in many VSC-HVDC projects. Compared with other converter topologies, the transfer relationship of harmonics on the AC and DC sides of MMC converters has not been studied in depth. In this paper, by studying the AC/DC harmonic conversion characteristics of MMC converters, it reveals the conversion law of MMC converters between AC/DC harmonics;through theoretical derivation, the quantitative calculation method of MMC harmonic transmission process is given. PSCAD simulation results prove the correctness of the above results. © 2021 IEEE.

关键词： Transmissions

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Mechanism and Influencing Factor Analysis of High Frequency Oscillation in PMSG-Based Wind Farm With Grid-Connected system

Mechanism and Influencing Factor Analysis of High Frequency ...

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IEEE International Conference on Energy Internet (ICEI)

作者： Chao Luo Yihua Zhu Libin Huang Jiawei Yu State Key Laboratory of HVDC Electric Power Research Institute China Southern Power Grid Guangzhou China National Energy Power Grid Technology R&D Centre Guangzhou China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou China

Under the background of vigorously developing wind power, permanent magnet synchronous generator (PMSG)-based wind turbines have been widely used in offshore wind farms. However, the high frequency oscillations (HFOs) of PMSG-based wind farms with grid-connected system have occurred frequently in recent years, which have a bad impact on the safe and stable operation of the power system. And current researches only preliminarily reveal the mechanism, which are lacking in discussion on the key factors involved in HFOs. This paper establishes the high frequency impedance model of PMSG-based wind farm with grid-connected system. To identify the key factors involved in HFO, the impedance sensitivity method is used to obtain the quantitative relationship of the influence of each parameter on HFO. It can be concluded that the control delay, LCL filter parameters, collector lines parameters have the greatest influence on the HFO of the wind farm, but the characteristic of negative resistance caused by control delay is the root cause of HFO. Finally, this paper establishes the model of PMSG-based wind farm with grid-connected system on the PSCAD/EMTDC and verifies the correctness of the theoretical analysis. The conclusions of this paper can provide a reference basis for the mitigation strategies of HFOs.

关键词： Wind energy generation Analytical models Sensitivity Wind farms Hafnium oxide Synchronous generators Delays

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