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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yunxiao Zhang Yuanxiang Zhou Ling Zhang Chenyuan Teng Zhongliu Zhou Meng Huang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

Electrical tree is one of the major issues for insulation failure in high-voltage direct current (HVDC) cable. In this paper, electrical tree initiation and growth characteristics of silicone rubber (SIR) are studied by optical tree observation system under DC and AC voltage with varied temperature. Moreover, tree channels are pictured and analyzed by 3D fluorescence imaging technology. Results show that the average tree initiation voltage, whether DC or AC, decreases exponentially with increasing temperature. However, the initiation voltage under positive DC voltages is much higher than that under AC voltages. AC tree growth pattern could be roughly divided into two modes: bush-like growing pattern and pine-like growing pattern, while DC trees stop growing after voltage stabilizes. 3D fluorescence tests show that DC tree branches are sparser and the channels are thinner. Based on the trap theory, mechanism of DC electrical tree in SIR is clarified. It is believed that different charge transport dynamics are the main reason for the differences in electrical tree behavior under DC and AC voltages.

关键词： Three-dimensional displays Temperature Shape HVDC transmission Conferences Fluorescence Space charge

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Fast Monte Carlo simulation of Dynamic power systems under Continuous Random Disturbances

arXiv

引用

arXiv 2020年

作者： Qiu, Yiwei Lin, Jin Chen, Xiaoshuang Liu, Feng Song, Yonghua State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China Department of Electrical and Computer Engineering University of Macau 999078 China

—Continuous-time random disturbances from the renewable generation pose a significant impact on power system dynamic behavior. In evaluating this impact, the disturbances must be considered as continuous-time random processes instead of random variables that do not vary with time to ensure accuracy. Monte Carlo simulation (MCs) is a nonintrusive method to evaluate such impact that can be performed on commercial power system simulation software and is easy for power utilities to use, but is computationally cumbersome. Fast samplings methods such as Latin hypercube sampling (LHS) have been introduced to speed up sampling random variables, but yet cannot be applied to sample continuous disturbances. To overcome this limitation, this paper proposes a fast MCs method that enables the LHS to speed up sampling continuous disturbances, which is based on the Itô process model of the disturbances and the approximation of the Itô process by functions of independent normal random variables. A case study of the IEEE 39-Bus System shows that the proposed method is 47.6 and 6.7 times faster to converge compared to the traditional MCs in evaluating the expectation and variance of the system dynamic response. Copyright © 2020, The Authors. All rights reserved.

关键词： Monte Carlo methods

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Deep learning-aided model predictive control of wind farms for AGC considering the dynamic wake effect

arXiv

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arXiv 2020年

作者： Chen, Kaixuan Lin, Jin Qiu, Yiwei Liu, Feng Song, Yonghua State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100087 China Department of Electrical and Computer Engineering University of Macau 999078 China

To provide automatic generation control (AGC) service, wind farms (WFs) are required to control their operation dynamically to track the time-varying power reference. Wake effects impose significant aerodynamic interactions among turbines, which remarkably influence the WF dynamic power production. The nonlinear and high-dimensional nature of dynamic wake model, however, brings extremely high computation complexity and obscure the design of WF controllers. This paper overcomes the control difficulty brought by the dynamic wake model by proposing a novel control-oriented reduced order WF model and a deep-learning-aided model predictive control (MPC) method. Leveraging recent advances in computational fluid dynamics (CFD) to provide high-fidelity data that simulates WF dynamic wake flows, two novel deep neural network (DNN) architectures are specially designed to learn a dynamic WF reduced-order model (ROM) that can capture the dominant flow dynamics. Then, a novel MPC framework is constructed that explicitly incorporates the obtained WF ROM to coordinate different turbines while considering dynamic wake interactions. The proposed WF ROM and the control method are evaluated in a widely-accepted high-dimensional dynamic WF simulator whose accuracy has been validated by realistic measurement data. A 9-turbine WF case and a larger 25-turbine WF case are studied. By reducing WF model states by many orders of magnitude, the computational burden of the control method is reduced greatly. Besides, through the proposed method, the range of AGC signals that can be tracked by the WF in the dynamic operation is extended compared with the existing greedy controller. Copyright © 2020, The Authors. All rights reserved.

关键词： Model predictive control

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Accelerating exploitation and integration of global renewable energy

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Innovation 2025年

作者： Wang, Jianxiao Chen, Xinjiang Zhuang, Minghao Li, Yan Ruan, Ziwen Wang, Yuhan Zhang, Ning Song, Jie He, Kebin Lu, Xi National Engineering Laboratory for Big Data Analysis and Applications Peking University Beijing100871 China Department of Industrial Engineering and Management College of Engineering Peking University Beijing100871 China Peking University Ordos Research Institute of Energy Ordos017000 China State Key Laboratory of Nutrient Use and Management College of Resources and Environmental Sciences China Agricultural University Beijing100193 China College of Environmental Science and Engineering Tongji University Shanghai200092 China School of Environment State Key Joint Laboratory of Environment Simulation and Pollution Control Tsinghua University Beijing100084 China State Key Lab of Power Systems Department of Electrical Engineering Tsinghua University Beijing100084 China Institute for Carbon Neutrality Tsinghua University Beijing100084 China

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Space Charge Characteristics of Oil-paper under AC/DC Composite Voltage

Space Charge Characteristics of Oil-paper under AC/DC Compos...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yuanxiang Zhou Xin Huang Ling Zhang Yunxiao Zhang Zhongliu Zhou Chenyuan Teng Lei Xue Meng Huang The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Haidian Beijing China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power Universiy Beijing China

ISBN: (纸本)9781728195728;9781728195735

Oil-paper insulation bears AC/DC composite voltage in converter transformers. However, the AC/DC space charge behavior is still not clear, which will result in electric field distortion, material aging and even insulation failure. In this work, the space charge distribution of oil-paper under the AC/DC composite voltage with the AC/DC ratio of 1:1, 1:3, 1:5, and 1:7, is studied by pulse electroacoustic (PEA) method, respectively. It was found that as DC component increases, the accumulated charge near the electrode decreases, while the interior charge increases. It suggests that DC stress mainly influences the amount and the depth of space charge accumulation. AC component has a relatively significant impact on the injection and extraction behavior of space charge near the electrode. Furthermore, AC/DC composite voltage enhances the migration of space charge compared with that under DC voltage. This research contributes to the further understanding of the space charge characteristics of oil-paper under AC/DC composite voltage, which will benefit the safe and stable operation of converter transformers.

关键词： Electrodes Conferences Space charge Oil insulation Aging Distortion Dielectrics

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Energy Management of a Residential Consumer with Uncertain Renewable generation: A Robust Dual Dynamic Programming Approach

Energy Management of a Residential Consumer with Uncertain R...

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Chinese control Conference (CCC)

作者： Dangwu Liu Zhongjie Guo Feng Chen Xiaodai Xue Shengwei Mei State Grid Anhui Electric Power CO. LTD Hefei P. R. China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9789881563903

ISBN: (纸本)9781728165233

This paper studies the dynamic operation of a residential electric energy system with distributed renewable generation. Energy streams among the power grid, local renewable plant, storage unit, and demand are considered; the temporal volatility of renewable generation is described by an uncertainty set, and the optimal operation problem gives rise to a multi-stage robust optimization. To deal with the non-anticipativity issue, the robust model is solved via robust dual dynamic programming (RDDP) approach. The the cost-to-go function is approximated by iteratively updating the upper and lower bounds, which can be obtained from forward-pass and backward pass procedures. Case studies validate the performance and advantage of the proposed method.

关键词： Uncertainty Robustness Dynamic programming Upper bound Optimization Heuristic algorithms Energy storage

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Wavelet-based data compression for wide-area measurement data of oscillations

引用

Journal of Modern power systems and Clean Energy 2018年第6期6卷 1128-1140页

作者： Lin CHENG Xinchi JI Fang ZHANG He HUANG Song GAO State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University State Grid Jiangsu Electric Power Company

This paper proposes a wavelet-based data compression method to compress the recorded data of oscillations in power systems for wide-area measurement systems. Actual recorded oscillations and simulated oscillations are compressed and reconstructed by the waveletbased data compression method to select the best wavelet functions and decomposition scales according to the criterion of the minimum compression distortion composite index, for a balanced consideration of compression performance and reconstruction accuracy. Based on the selections, the relationship between the oscillation frequency and the corresponding optimal wavelet and scale is discussed, and a piecewise linear model of the base-2 logarithm of the frequency and the order of the wavelet is developed, in which different pieces represent different scales. As a result, the wavelet function and decomposition scale can be selected according to the oscillation frequency. Compared with the wavelet-based data compression method with a fixed wavelet scale for disturbance signals and the real-time data compression method based on exception compression and swing door trending for oscillations, the proposed method can provide high compression ratios and low distortion rates.

关键词： Data compression Oscillation Wavelet transform Wide-area measurement system(WAMS)

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Research on the Substitution Ability of Battery Energy Storage system for Thermal power Units in Frequency Regulation

Research on the Substitution Ability of Battery Energy Stora...

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Sustainable power and Energy Conference (iSPEC)

作者： Huan Zhu Kaifeng Wang Ying Qiao Lirong Xie Guojing Liu State Grid Jiangsu Electric Power Company Economic Research Institute Nanjing China Xinjiang University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments of Electrical Engineering (Tsinghua University) Urumqi and Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments of Electrical Engineering Tsinghua University Beijing China Xinjiang University Urumqi China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

When penetration levels of renewable energy of power system are increased, the proportion of thermal power units will gradually decrease. This will cause the frequency regulation capacity of the power system to gradually decline. To this end, battery energy storage systems are widely used to frequency regulation in the power system. However, the frequency regulation ability of battery energy storage system to substitute thermal power units has not yet been quantified. In this paper, it introduces two frequency regulation method models. In the proposed models, the influence of different energy storage participation degrees on the effect of frequency regulation is analyzed, and a power and energy indicators system for quantifying energy storage substitution ability is proposed based on the advantages of frequency regulation with energy storage. The simulation results indicate that the ability of energy storage to substitute thermal power units is about 20-35 in terms of rapid energy supply when the installed capacity is same.

关键词： Renewable energy sources simulation power system stability Stability analysis Batteries Frequency control Thermal stability

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Commutation Failure Mitigation Method Based on Improved Commutation Area in HVDC system

Commutation Failure Mitigation Method Based on Improved Comm...

引用

International Conference on Advanced power System Automation and Protection (APAP)

作者： Haozong Wang Xinzhou Dong State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728117225

ISBN: (纸本)9781728117232

Commutation failure (CF) is one of the major concerns in high-voltage direct current (HVDC) transmission system. Of many methods to mitigate CF, advancing firing angle is preferred one since it can be easily implemented in current HVDC controllers without extra hardware modification. However, methods in previous works either lack for quantitative analysis or based on much strong hypothesis. In this paper, we propose a novel CF mitigation method based on improved commutation area. The salient feature of proposed strategy is that DC current is not considered as a constant under fault conditions. simulations on PSCAD/EMTDC software demonstrate the good performance of proposed method.

关键词： HVDC transmission Circuit faults Mathematical model Firing Valves Inverters Resistance

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Analysis of Application of Superconducting Fault Current Limiter to AC Line of HVDC

Analysis of Application of Superconducting Fault Current Lim...

引用

International Conference on Advanced power System Automation and Protection (APAP)

作者： Binshu Chen Xinzhou Dong Tsinghua University Key Lab of Control and Simulation of Power Systems and Generation Equipment China

ISBN: (数字)9781728117225

ISBN: (纸本)9781728117232

In LCC-HVDC hybrid grid, commutation failure is an important factor affecting system stability. When there is a fault or a large voltage fluctuation in AC line of LCC-HVDC, a commutation failure will occur. Fault current limiter (FCL) can limit the fault current and prevent commutation failure. Superconducting current limiters using superconducting materials as the core component, have no power loss and do not affect the dynamic performance of the system during normal operation. This article analyze how SFCL acts to suppress commutation failure in AC/DC hybrid systems, and describes the various types of SCFCLs and their limitations for this scene. By building simulation models of SCFCLs applied to AC line of LCC-HVDC invert, the author analyzes the effect of SCFCL on the hybrid grid.

关键词： Superconducting transmission lines Resistance Superconducting coils Fault currents Magnetic fields Inverters Impedance

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