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

作者： Jing CAI Xinzhou DONG State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728117225

ISBN: (纸本)9781728117232

DC-line fault recovery sequence (DFRS) is widely implemented in LCC-HVDC system to realize fast recovery in case of temporary fault. When permanent fault occurs, restart still happens several times as preset, resulting in repeated impacts and reducing the stability and reliability of the system. An adaptive restart for DC line fault is studied in this paper to deal with this problem. Firstly, the converter valves states and DC voltage characteristics under temporary fault and permanent fault are analyzed respectively. Then, a method based on DC voltage control is proposed to distinguish different fault states. Current DFRS strategy is improved by adding this process, through which the fault pole will only restart after the temporary fault disappearing, while directly blocked when a permanent fault is recognized. Fault handling time can be shortened and negative effects of DC line fault are minimized. The simulation results verify feasibility and effectiveness of proposed method.

关键词： Firing HVDC transmission Inverters Voltage control Valves Rectifiers Thyristors

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An Explicit MPC Based on Galerkin Method for AGC Considering Volatile generations

An Explicit MPC Based on Galerkin Method for AGC Considering...

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IEEE power and Energy Society General Meeting

作者： Yiwei Qiu Jin Lin Feng Liu Yonghua Song State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The University of Macau Macau China

Imbalance of generation and load caused by volatile generations poses challenges on frequency regulation. AGC is required to respond to the generation fluctuations without violating operational and security constraints. While explicit model predictive control (EMPC) provides an approach, the partition number of the piecewise affine control laws grows exponentially with the number of constraints and prediction/control horizons, which hinders its application in large systems. In this paper, we propose an EMPC approach for AGC by approximating the control laws using Legendre polynomial series expansions, thus entirely eliminating the partition issue. Galerkin method is applied to the KKT conditions of EMPC's multiparametric quadratic programming (mp-QP) problem to compute the approximations. Case study in New England 39-bus system verifies the performance and efficiency of the proposed controller.

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A Review on Virtual power Plants Interactive Resource Characteristics and Scheduling Optimization 3

A Review on Virtual Power Plants Interactive Resource Charac...

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3rd IEEE Conference on Energy Internet and Energy System Integration, EI2 2019

作者： Cheng, Lin Zhou, Xuyan Yun, Qiuchen Tian, Liting Wang, Xuanyuan Liu, Zhen Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing China Beijing Jiaotong University Center of Electrical Laboratories and National Teching Center of Electrotechnics and Electronics Beijing China State Grid Jibei Electric Power Company Jibei Electric Power Company Power Exchange Center Beijing China State Grid Jibei Electric Power Company North China Electric Power Research Institute Beijing China

ISBN: (纸本)9781728131375

With a high penetration of distributed energy resources (DER) connected to the power grid, the reliability and safety of the power grid compromised by the uncertainty of energy output. Many utilities adopted strategies to abandon excessive wind and solar energy generation to ensure reliable operations of the power grid. The virtual power plant (VPP) is a way of aggregating various types of energy resources and optimizing resources utilization. It participates in the electricity market and improves the utilization of energy resources within the VPP. VPP provides services such as peak shaving, frequency regulation, and emergency power support for the power grid. It intends to prevent the negative impact caused by the uncertainty of power generation of the distributed energy resources. In this paper, three kinds of typical VPP interactive resource are introduced, which differ in characteristics, control modes, and output characteristics. In addition, the VPP achieves improved energy efficiency through rational optimized resource allocation and optimized scheduling, including internal and external scheduling optimization. © 2019 IEEE.

关键词： Virtual power Plants

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Excellent electrical properties of zinc-oxide varistors by tailoring sintering process for optimizing line-arrester configuration

Excellent electrical properties of zinc-oxide varistors by t...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Pengfei Meng Wei Cao Chao Chen Shuai Wan Heng Xu Jun Hu Jinliang He Tsinghua University Beijing China Wuhan NARI Limited Liability Company State Grid Electric Power Research Institute Wuhan China Guangdong Aikang Electric Power Co. Ltd Guangzhou China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

We optimized the excellent electrical performance of zinc-oxide (ZnO) varistors doping of aluminum and indium by tailoring the sintering process. The surface morphology, nonlinear volt ampere properties, capacitance-voltage characteristics, and dielectric analyses were carried out. At a given aluminum and indium concentration, the average sample grain size ( d) increased as lengthening sintering time from 0.5 to 2.5 h. The voltage gradient ( E1mA) decreased from 602.4 V/mm to 356.7 V/mm. The residual voltage of the sintered varistors at the lightning impulse current ( 8/20 μs) decreased as the samples sintering holding time extended from 0.5 to 2.0 h. When the ZnO varistor was sintered for 1.5 h, the samples showed an excellent performance, with a reference voltage of 479.3 V/mm at 1 mA DC. When assembled in the line surge arresters, the obtained high-voltage-gradient ZnO varistors can decrease their length and residual voltage, which allows for better coordination of the line surge arrester with the insulators. This study has great significance to optimize line-arrester configurations and improve power-system stability.

关键词： Zinc oxide Varistors Arresters II-VI semiconductor materials Surges Insulators Dielectrics

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Flexible unbalanced control with peak current limitation for virtual synchronous generator under voltage sags

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Journal of Modern power systems and Clean Energy 2018年第1期6卷 61-72页

作者： Tianwen ZHENG Laijun CHEN Yan GUO Shengwei MEI State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Qinghai Key Lab of Efficient Utilization of Clean Energy New Energy Photovoltaic Industry Research Center Qinghai University

Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage *** overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is *** on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive *** the injected currents are kept within safety values for a better utilization of the VSG power ***,the experimental platform is *** results demonstrate the validness and effectiveness of the proposed control strategy.

关键词： Virtual synchronous generator Unbalanced control Current reference generator power reference generator Voltage sags

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A Voltage-fed control Method with Automatic Bidirectional power Switching Capability for CLLC and SR Buck Based Two Stage Converters

A Voltage-fed Control Method with Automatic Bidirectional Po...

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International Conference on power Electronics and Motion control (IPEMC)

作者： Huan Chen Hongsheng Chong Kai Sun You Zhou Hang Zhou John Fletcher State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Nation Institute of Clean and Low Carbon Energy Beijing China School of Electrical Engineering and Telecommunications University of New South Wales Sydney Australia

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

The CLLC converter is widely used in bidirectional power conversion systems. The conventional control method for CLLC converter is pulse frequency modulation (PFM) method. However, PFM method can not realize smooth bidirectional power switching, because the driver signals for the primary and the secondary side switches are asymmetric. This paper proposed a voltage-fed control method for CLLC and Synchronous Rectified (SR) Buck two stage converters, which can realize the automatic and smooth bidirectional power switching for CLLC stage. In the proposed control method, the PWM signals for both the primary and the secondary switches are the same. The effectiveness of the proposed voltage-fed control method is verified by experiments.

关键词： Prototypes Switches Pulse width modulation control systems Automatic voltage control power electronics Transient analysis

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Development and test research of 10kv DC circuit breaker based on the principle of coupled negative voltage

Development and test research of 10kv DC circuit breaker bas...

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The 16th IET International Conference on AC and DC power Transmission (ACDC 2020)

作者： W. Li B. Liu F. Xiao H. Wang Y. Wang W. Xie Z. Yu Shandong Taikai High-Voltage Switchgear Co. Ltd. Tai’an China China Electric Power Research Institute Beijing China Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment (Department of Electrical Engineering Beijing China

With the increase of multi-terminal flexible DC distribution network projects, medium-voltage DC circuit breaker, as the key equipment to remove DC short-circuit fault, plays a key role in the operation reliability of the whole DC distribution network. In order to meet the engineering needs of DC distribution network, a 10kV hybrid DC circuit breaker based on the coupling negative voltage principle is developed in this paper. Firstly, the topology and working principle of the DC circuit breaker are introduced. Furthermore, the design scheme of key components including fast mechanical switch, power electronic switch and coupling negative voltage device is given. Finally, a 10kV hybrid DC circuit breaker prototype is developed and tested. The results show that the 10kV hybrid DC circuit breaker can break 15kA short circuit current within 2ms, and has the characteristics of low loss and high reliability.

关键词： circuit breakers short-circuit currents DC distribution systems power distribution faults power distribution reliability

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The Design and Field Test of a Shunt Unified power Quality controller for Mitigating Voltage Sags

The Design and Field Test of a Shunt Unified Power Quality C...

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IEEE Student Conference on Electric Machines and systems

作者： Chang Liu Lin Xu Wei Wei Yingdong Wei Hua Yang Xueyuan Liu Yi Zhang Ying Wang Electric Power Research Institute of State Grid Sichuan Electric Power Company Chengdu China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China School of Electrical Engineering and Automation Fuzhou University Fuzhou China College of Electrical Engineering Sichuan University Chengdu China

ISBN: (数字)9781728156224

ISBN: (纸本)9781728156231

A shunt unified power quality controller (S-UPQC) is developed and has been tested in the field in order to confirm its performance at mitigating voltage sags for sensitive power consumers. The S-UPQC keeps the magnitude of the voltage supply for power consumers constant by acting as a voltage source when voltage sags occur in the power grid. In this paper, a smooth switching strategy is designed to smooth the voltage disturbance of power consumers when the power supply switches between the S-UPQC and the grid. simulation results are presented to show its high performance. A prototype of S-UPQC is developed and a field test has been conducted. During its operation, the performance of the SUPQC at mitigating voltage sags within actual power systems is confirmed.

关键词： simulation power quality Prototypes Switches Production Reliability Switching circuits

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Ultra-short-term wind power prediction based on variational mode decomposition and clustering method

Ultra-short-term wind power prediction based on variational ...

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第三十八届中国控制会议

作者： Liu Chenyu Zhang Xuemin Mei Shengwei Huang Shaowei State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering Tsinghua University)

Wind power ultra-short-term prediction plays a key role in day scheduling of power systems and cross-provincial power trading. However, the randomness and non-stationary nature of wind power, and the mismatch between the training data and the predicted data have become the main obstacles for the improvement of prediction accuracy. This paper proposes a prediction algorithm based on variational mode decomposition(VMD) and clustering. Firstly, the original non-stationary sequence is transformed into several relatively stationary modes utilizing VMD. Secondly, key features can be conveniently selected for each mode, which has a central frequency. Then the k-means clustering method is used to cluster each mode into several typical patterns based on correlation coefficient based distance definition. Finally, the method of "offline training, online matching" is adopted to perform training and prediction process. The actual data of a wind farm in Jilin Province was used to verify the results. The results show that the proposed method can improve the accuracy of ultra-short-term in multi-step prediction of wind power.

关键词： wind power ultra-short-term prediction variational mode decomposition stationary

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Comprehensive comparison and analysis of non-inverting buck boost and conventional buck boost converters

Comprehensive comparison and analysis of non-inverting buck ...

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作者： Weng, Xing Xiao, Xiang He, Weibin Zhou, Yongyan Shen, Yu Zhao, Wei Zhao, Zhengming State Key Lab of Control and Simulation Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China Guangdong Electric Power Research Institute Guangdong510080 China Dongguan Power Supply Bureau Guangdong Power Grid Company Dongguan523000 China

The non-inverting buck boost (NIBB) converter has attracted significant attention in recent years, as it shares ground between input and output, and the voltage stress of switches is lower. In order to investigate the differences between NIBB and conventional buck boost converters, a comprehensive comparison and analysis of these two converters were conducted in terms of their operation principles, which includes multi-mode control strategy and dual-edge modulation here, and also the characteristics of switches and passive components in the two converters were analysed. The results show that NIBB is better than conventional buck boost circuit in these aspects of electrical stress, power loss, cost, passive component volume, and so on. Two prototypes for the two converters with 10 kW/20 kHz were designed and simulated, respectively, for verifying the results. Analytical and simulated results confirmed the conclusions. © 2019 Institution of Engineering and *** right reserved.

关键词： Buck-Boost converter

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