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Smallest Eigenvalues Based Logarithmic Derivative Method for Computing Dominant Oscillation Modes in Large-Scale power systems

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Journal of Modern power systems and Clean Energy 2024年第3期13卷 747-756页

作者： Linguang Wang Xiaorong Xie Wenkai Dong Yong Mei Aoyu Lei Department of Electrical Engineering State Key Laboratory of Power System Tsinghua University Beijing China Power Dispatching and Control Center of China Southern Power Grid Guangzhou China

With the rapid integration of renewable energy, wide-band oscillations caused by interactions between power electronic equipment and grids have emerged as one of the most critical stability issues. Existing methods are usually studied for local power systems with around one hundred nodes. However, for a large-scale power system with tens of thousands of nodes, the dimension of transfer function matrix or the order of characteristic equation is much higher. In this case, the existing methods such as eigenvalue analysis method and impedance-based method have difficulty in computation and are thus hard to utilize in practice. To fill this gap, this paper proposes a novel method named the smallest eigenvalues based logarithmic derivative (SELD) method. It obtains the dominant oscillation modes by the logarithmic derivative of the $k$ -smallest eigenvalue curves of the sparse extended nodal admittance matrix (NAM). An oscillatory stability analysis tool is further developed based on this method. The effectiveness of the method and the tool is validated through a local power system as well as a large-scale power system.

关键词： power system stability Eigenvalues and eigenfunctions Stability analysis Oscillators Mathematical models Impedance Computational efficiency Transmission line matrix methods Thermal stability Sparse matrices

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Improved Insulation Properties of Polypropylene With Highly Orientated Lamellar Induced by NonIsothermal Shear Stress

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IET Nanodielectrics 2025年第1期8卷

作者： Huang, Lei Song, Yan-Hui Yin, Li-Juan Zhong, Shao-Long Dang, Zhi-Min Department of Electrical Engineering State Key Laboratory of Power System Operation and Control Tsinghua University Beijing China ZhongYuan Electric Laboratory Xuchang China

Polypropylene plays an irreplaceable role in electrical insulation and electrostatic capacitors and has been extensively studied with its microstructure and insulation properties optimised for high-power density miniaturised devices. The extrinsic modifiers or industrial upgrading have not yet achieved a remarkable breakthrough in either concise theory or comprehensive performance. Here, we develop a nonisothermal shear process on melt to regulate the nucleation density and the lamellar orientation along the surface and reveal pore defects in disorder boundaries between spherulites as the microscopic nature of the property bottleneck. The high-rated shear process induces a crystallographic surface texture of (1 1 0) planes from which the elimination of micro-defect benefits. Our high-rated shear strategy achieves an excellent dielectric strength of 573.7 MV/m with an increase of 33% and an improved insulation resistance by 130% at 100 MV/m with the minimised absorption of injected current. © 2025 The Author(s). IET Nanodielectrics published by John Wiley & Sons Ltd on behalf of The Institution of engineering and Technology.

关键词： Crystal orientation

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Capacitor Voltage Balancing Strategy Based on Zero-Sequence Voltage Injection for Half-Wave Commutated Modular Multilevel Converter 10

Capacitor Voltage Balancing Strategy Based on Zero-Sequence ...

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10th IEEE International power Electronics and Motion control Conference, IPEMC 2024 ECCE Asia

作者： Fu, Nan Liu, Bao Xu, Yunfei Zhu, Sitong Wang, Kui Li, Yongdong Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Beijing100084 China State Grid Smart Grid Research Institute Co. Ltd State Key Laboratory of Advanced Power Transmission Technology Changping Beijing China Electric Power Research Institute of State Grid Liaoning Electric Power Co. Ltd. Shenyang110000 China

ISBN: (纸本)9798350351330

Half-wave commutated modular multilevel converter (HWC-MMC) is suitable for high-voltage large-capacity AC-AC conversion, and an appropriate capacitor voltage balancing strategy is essential. This paper analyzes the condition of capacitor voltage balancing and proposes a capacitor voltage balancing strategy based on optimal zero-sequence voltage injection using the model predictive control. Finally, the simulation is carried out to verify the proposed strategy. © 2024 IEEE.

关键词： Model predictive control

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Investigation of Near-Fundamental-Frequency Oscillation in a Renewable power Integrated system with MMC-HVDC Transmissions

Investigation of Near-Fundamental-Frequency Oscillation in a...

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

作者： Xiaoyu Tian Wenkai Dong Wenhui Zhai Guixing Yang Pengpeng Kang Xiaorong Xie Power Dispatching Control Center State Grid Xinjiang Electric Power Co. Ltd Urumqi China State Key Laboratory of Power System Operation and Control (Department of Electrical Engineering) Tsinghua University Beijing China

ISBN: (数字)9798331523527

ISBN: (纸本)9798331523534

Near-fundamental-frequency oscillations (NFFOs) have been observed in practical renewable power integrated system via MMC-HVDC, of which the mechanism is not fully revealed yet. Therefore, in this paper, potential dominant influencing factors of the NFFO are explored based on a general renewable power integrated system at first. Then the equivalent circuit model of the system is built. By calculating the total resistance, the physical mechanism of the NFFO is revealed.

关键词： Damping Resistance Renewable energy sources Resonant frequency Energy Internet system integration Integrated circuit modeling Phase locked loops Oscillators Equivalent circuits

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Inspection Text Classification of power Equipment Based on TextCNN 16th

Inspection Text Classification of Power Equipment Based on T...

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16th Annual Conference of China Electrotechnical Society, ACCES 2021

作者： Chen, Jianning Zhou, Yuanxiang Ge, Jiamin State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789811918698

A large number of text and reports about the power equipment are generated in power system, which consist of implicit information of operation condition and insulation status. With the development of convolutional neural network (CNN), the inspection text can be analyzed intelligently to improve the reliability of power system. In order to extract valuable information from inspection text for state evaluation of power equipment in local area, an information extraction model for inspection text based on TextCNN is proposed, improved and verified. First, the feature embedding of inspection text were performed by Word2Vec method. Secondly, the corpus were augmented with back translation method. Then, the TextCNN was adopted to classify the risk level of the power equipment or area involved in the inspection text. Finally, the classification results from the model were evaluated by classification accuracy, F1 score, confusion matrix and compared with the model based on BiLSTM and RCNN. The results demonstrated that the performance of TextCNN was the best among the three models on augmented dataset by back translation method with ACC and F1 scores of 0.9087 and 0.9099, respectively, which is the most suitable model among these three for recognition and classification of inspection text of power equipment. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Inspection

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Electromagnetic and Mechanical Transmission Role of Poles in vibration of PMDC motor

Electromagnetic and Mechanical Transmission Role of Poles in...

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2022 International Conference on electrical Machines, ICEM 2022

作者： Wang, S.M. Gu, Z.Q. Hong, J.F. Yang, Z.L. Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Beijing100084 China

ISBN: (数字)9781665414326

ISBN: (纸本)9781665414326

In this paper, the pivot role of permanent-magnet pole in the electromagnetic and mechanical transfer process of the vibration in PMDC motor is clarified, and the transfer function is established to describe the transfer process of electromagnetic force from the bottom of the magnetic pole to the stator yoke. The expression of radial electromagnetic force in air-gap is analytically calculated, the characteristics of harmonic components are obtained, and the reason why high order force density produces low order concentrated force and bending moment is explained. Based on the characteristics of harmonics, the relationship between the polar arc coefficient and concentrated force or bending moment is explained. Finally, the key role of magnetic poles in the vibration transmission of PMDC motor is summarized. © 2022 IEEE.

关键词： Bending moments

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Energy Management and operational control Methods for Grid Battery Energy Storage systems

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CSEE Journal of power and Energy systems 2021年第5期7卷 1026-1040页

作者： Xiangjun Li Shangxing Wang State Key Laboratory of Control and Operation of Renewable Energy and Storage Systems Energy Storage and Electrical Engineering DepartmentChina Electric Power Research Institute.Beijing 100192China.

Energy storage is one of the key means for improving the flexibility,economy and security of power *** is also important in promoting new energy consumption and the energy ***,energy storage is expected to support distributed power and the micro-grid,promote open sharing and flexible trading of energy production and consumption,and realize multi-functional *** recent years,with the rapid development of the battery energy storage industry,its technology has shown the characteristics and trends for large-scale integration and distributed applications with multi-objective *** a grid-level application,energy management systems(EMS)of a battery energy storage system(BESS)were deployed in real time at utility control centers as an important component of power grid *** on the analysis of the development status of a BESS,this paper introduced application scenarios,such as reduction of power output fluctuations,agreement to the output plan at the renewable energy generation side,power grid frequency adjustment,power flow optimization at the power transmission side,and a distributed and niohile energy storage system at the power distribution *** studies and application status of a BESS in recent years were *** energy management,operation control methods,and application scenes of large-scale BESSs were also examined in the study.

关键词： Battery energy storage system(BESS) energy management systems(EMS) multi-objective collaborative control new energy integration power grid ancillary service.

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Decentralized Robust Energy Management of Multi-area Integrated Electricity-gas systems

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Journal of Modern power systems and Clean Energy 2021年第6期9卷 1478-1489页

作者： Nan Jia Cheng Wang Wei Wei Tianshu Bi IEEE State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Department of Electrical Engineering Tsinghua University

This paper proposes a fast and decentralized solution methodology for the robust operation of multi-area integrated electricity-gas systems(M-IEGSs).A deterministic reformulation is obtained for the two-stage robust model by applying the linear decision rule based electrical reserve utilization scheme as well as regulating the distributed gas *** linear approximations are developed for the nonconvex Weymouth equation in the gas network to determine the gas flow *** penalty convex-concave procedure(P-CCP)is then adopted to refine a feasible local optimum for the nonconvex model with an acceleration *** decentralized decision-making is enabled by the alternating direction multipliers method(ADMM).The convergence as well as computation performance of the overall solution procedure can be guaranteed as only convex optimizations are *** results validate the effectiveness of the proposed methods as well as the benefits of the proposed convex programing based solution procedure.

关键词： Convex optimization decentralized robust optimization energy management linear approximation integrated electricity-gas system

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Active and Reactive power Optimization of VSG-IIDG during Fault Ride Through Considering Inrush Fault Current Constraints

Active and Reactive Power Optimization of VSG-IIDG during Fa...

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

作者： Liu Yang Jiamei Zhang Yuebin Zhou Yue Wu State Key Laboratory of HVDC Electric Power Research Institute (EPRI) China Southern Power Grid (CSG) Guangzhou China Department of Electrical Engineering State Key Laboratory of Power System Operation and Control Tsinghua University Beijing China

ISBN: (数字)9798331523527

ISBN: (纸本)9798331523534

As the penetration rate of renewable energy continues to rise, grid connection standards now require renewable energy systems to achieve fault ride-through during grid faults and provide voltage support. However, voltage support occupies converter capacity, reducing its available active power output and threatening system frequency in high renewable ratio systems. The virtual synchronous machine (VSGs) can regulate voltage and frequency similar to conventional generators, although inrush currents pose a threat to inverter safety. This paper proposes an optimization strategy for active and reactive power during grid faults for VSGs. Both voltage and frequency support are considered for VSGs. The rate of change of frequency (RoCoF) and inrush current constraints are constructed and incorporated into the optimal model to guarantee the security of the frequency and prevent the damage of the converter. Case studies validate the effectiveness of the proposed model.

关键词： Renewable energy sources Reactive power system integration Frequency conversion Safety Security Voltage control Synchronous machines Inrush current Standards

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Optimal Allocation of Synchronous Condensers in Renewable power Grids 7

Optimal Allocation of Synchronous Condensers in Renewable Po...

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7th IEEE Conference on Energy Internet and Energy system Integration, EI2 2023

作者： Han, Zijiao Na, Guangyu Dong, Wenkai Xie, Xiaorong Jia, Qi Su, Yuze State Grid Liaoning Electric Power Supply Co. Ltd. Shenyang China Tsinghua University State Key Laboratory of Power System Department of Electrical Engineering Beijing China

ISBN: (纸本)9798350345094

Optimal allocation of synchronous condensers is one of the most-commonly-used ways to improve the operation performance of renewable power generators in weak grid. However, except for optimality, equity of the allocation should also be taken seriously to ensure the acceptability of the scheme. To do so, in this paper, an optimization model for the allocation of synchronous condensers considering equity is established at first. By inducing a penalty term which measures equity of the allocation, scheme with the lowest investment and the best equity can be selected. Besides, the main constraint is to ensure that short circuit ratios seen by the renewable power generators are no less than the required level. Second, since the optimal allocation of synchronous condensers is a problem of non-linear integer programming, an improved genetic algorithm is utilized for the solution of the optimization. Finally, effectiveness of the optimization model proposed is validated via study cases. The results indicate that the method proposed can ensure equity of the allocation scheme while maintaining the lowest cost. © 2023 IEEE.

关键词： Genetic algorithms

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