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Analyses on Frequency Transmission Characteristic of Traveling Wave in Distribution power System

Analyses on Frequency Transmission Characteristic of Traveli...

2011 International Conference on Advanced power System Automation and Protection (APAP 2011)(2011年继电保护与电力系统自动化国际会议)

作者： Jun Wang Shenxing Shi Xinzhou Dong Bin Wang Stale Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsmghua University IIai-dian District. Beijing 100084 China

Under the skin effect caused by the alternating electromagnetic field, the transmission line parameters changes with frequency, and different line resistivity, surge impedance, wave speed are presented in one line under the different frequency bands of signal. This phenomenon is usually called Frequency transmission characteristic, which is mainly discussed in this paper. This paper first studied the line resistivity, wave speed and surge impedance of zero-mode component and line-mode component in different frequency bands. Then, the line structure and its effection on Frequency transmission characteristic are presented. Last, the frequency transmission characteristic on a certain line fault is discussed based on a typical distribution system model. The research in this paper is meaningful for future study on the fault feeder selection and fault location technology based on traveling wave in the distribution system.

关键词： Frequency transmission characteristic traveling wave distribution power system zero-mode component line-mode component wavelet transform

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Tertiary regulation of cascaded run-of-the-river hydropower in the islanded renewable power system considering multi-timescale dynamics

arXiv

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arXiv 2020年

作者： Qiu, Yiwei Lin, Jin Liu, Feng Dai, Ningyi Song, Yonghua Chen, Gang Ding, Lijie State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100087 China State Key Laboratory of Internet of Things for Smart City University of Macau 999078 China State Grid Sichuan Electric Power Research Institute Chengdu610000 China

To enable power supply in rural areas and to exploit clean energy, fully renewable power systems consisting of cascaded run-of-the-river hydropower and volatile energies such as pv and wind are built around the world. In islanded operation mode, the primary and secondary frequency control, i.e., hydro governors and automatic generation control (AGC), are responsible for the frequency stability. However, due to limited water storage capacity of run-of-the-river hydropower and river dynamics constraints, without coordination between the cascaded plants, the traditional AGC with fixed participation factors cannot fully exploit the adjustability of cascaded hydropower. When imbalances between the volatile energy and load occur, load shedding can be inevitable. To address this issue, this paper proposes a coordinated tertiary control approach by jointly considering power system dynamics and the river dynamics that couples the cascaded hydropower plants. The timescales of the power system and river dynamics are very different. To unify the multi-timescale dynamics to establish a model predictive controller that coordinates the cascaded plants, the relation between AGC parameters and turbine discharge over a time interval is approximated by a data-based second-order polynomial surrogate model. The cascaded plants are coordinated by optimising AGC participation factors in a receding-horizon manner, and load shedding is minimised. simulation of a real-life system with real-time pv data collected on site shows the proposed method significantly reduces load loss under pv volatility. Copyright © 2020, The Authors. All rights reserved.

关键词： Electric load shedding

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Modeling and analysis of secondary controlled virtual synchronous generator with dynamic droop for microgrid

Modeling and analysis of secondary controlled virtual synchr...

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

作者： Weihang Yan David Wenzhong Gao Fang Zhang Lin Cheng Shijie Yan Department of Electrical and Computer Engineering University of Denver Denver USA State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China College of Information Science and Technology Northeastern University Shenyang China

ISBN: (纸本)9781538614280

In this paper, a dynamic droop mechanism is proposed to damp the synchronizing oscillation that exists in a virtual synchronous generator based distributed generator system without varying the steady-state active-power-loop droop coefficient. In order to eliminate the steady-state error introduced due to load changes or generator trips, a distributed secondary controller based on extremum seeking is employed so that microgrid frequency can be restored to nominal value. Besides, the small-signal model of virtual synchronous generator system is presented under d-q reference frame where virtual synchronous generator is deployed as a PV node. Moreover, the linearized system model of virtual synchronous generator with dynamic droop mechanism is derived and its advantage is discussed. Finally, a modified IEEE 14 bus microgrid system is established in Matlab/Simulink platform. simulation results demonstrate the validity and feasibility of the proposed method.

关键词： Mathematical model Microgrids Synchronous generators Frequency control Inverters power system stability power system dynamics

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A convex hull based intertemporal loadability set approximation method

A convex hull based intertemporal loadability set approximat...

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2020 Tsinghua - HUST-IET Electrical Engineering Academic Forum

作者： Xinfei Yan Haiwang Zhong Zhenfei Tan Junfeng Yang Dept. Electrical Engineering Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing China Power Dispatch & Control Center State Grid Corp. of China Beijing China

ISBN: (纸本)9781839533914

The uncertainty of renewable energy sources has aroused the interests in depicting the ability of power systems to accommodate the variations. Loadability set is one of the typical methods to characterize the feasible sets of power systems with uncertainties. The existing literature on loadability set do not incorporate intertemporal constraints, while for some cases like security check, intertemporal constraints are necessary and important. This paper firstly adapts loadability set to security check, enabling it to depict the capability of power systems to accommodate load variations. Singular value decomposition (SVD) and progressive vertex enumeration (PVE) are introduced to lighten the computational burden caused by multiple periods. The computational time can be traded off with the precision of approximation to the loadability set. Case studies verify that the loadability set can be approximated with proper precision.

关键词： Loadability feasible set convex hull security check loading capacity safety check convex hull power systems Approximation method

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Novel Connection Scheme of Backup power Supply Adaptive to Distribution Line Non-Communication Protection and New Criterion for High Voltage and Large Capacity Induction Motor

Novel Connection Scheme of Backup Power Supply Adaptive to D...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Kun Liu Xinzhou Dong Zhiqian Bo State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China AREVA T&D Automation슠and Information Systems Stafford UK

This paper presents a new practical backup power supply connection scheme for distribution line non-communication protection (DNCP). simulation tests have been conducted using the alternate transient program (ATP) with respect to a typical single circuit breaker multi-section system. The results prove that the new scheme is able to not only recover the power supply of loads on healthy lines automatically, but also create disturbances in favor of accelerated over current (AOC) criterion. Aiming at the failure of directional under voltage (DUV) criterion derived from high voltage and large capacity induction motor load, a novel criterion using the increment of reactive power is proposed.

关键词： Emergency power supplies Voltage Induction motors power system protection Circuit testing Circuit simulation System testing power system transients Circuit breakers power supplies

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Multiple-Stage Inter-temporal Flexibility for Planning: A Non-sequential Probabilistic Production simulation Approach

Multiple-Stage Inter-temporal Flexibility for Planning: A No...

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power, Energy and Electrical Engineering (CPEEE), International Conference on

作者： Ying Qiao Haibo Li Jiheng Jiang Guobin Fu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China Sichuan Energy Internet Research Institute Tsinghua University Chengdu China State Grid Qinghai Provincial Electric Power Company Xining China

ISBN: (数字)9781728177175

ISBN: (纸本)9781728177182

High wind energy curtailment during winter and early spring in north China has drawn widespread concern in recent years, which, at source, results from the shortage of power system flexibility. Therefore, power system needs to consider the flexibility in planning stage. However, current flexibility metric is difficult to calculate and be applied in to the optimal planning. A non-sequential production simulation model with only input data of the cumulative probability function and/or probability density function of heat demand, electricity demand, and wind power is proposed, which is used to obtain the probability distribution of the production for generators according to least cost principle. Then the flexibility metric can be easily calculated based on the production results. simulations were performed based on the actual data of a large wind power zone in north China. Multiple flexibility metric was evaluated and compared with the wind power curtailment, which shows the strong correlation between them. Finally, the impact of flexible resources on the flexibility metric was analyzed.

关键词： Measurement Production Wind power generation Data models Planning Space heating Resistance heating

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Fault diagnosis for multi-energy flows of energy internet: Framework and prospects

Fault diagnosis for multi-energy flows of energy internet: F...

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2017 IEEE Conference on Energy Internet and Energy System Integration, EI2 2017

作者： Wang, Tao Wang, Jun Fan, Zhennan Wei, Xiaoguang Zang, Tianlei Pérez-Jiménez, Mario J. Huang, Tao School of Electrical Engineering and Electronic Information Sichuan Province Key Laboratory of Power Electronics Energy-saving Technologies and Equipment Key Laboratory of Fluid and Power Machinery Ministry of Education Xihua University Chengdu China School of Electrical Engineering Southwest Jiaotong University Chengdu China State Key Laboratory of Security Control and Simulation of Power Systems and Large Scale Generation Department of Electrical Engineering Tsinghua University Beijing China Research Groupon Natural Computing Department of Computer Science and Artificial Intelligence University of Sevilla Sevilla Spain Department of Energy Politecnico di Torino Torino Italy

ISBN: (纸本)9781538614273

Energy Internet (EI) is an inevitable development trend of energy systems under the background of technology development, environmental pressure and energy transition. Multi-energy flow coupling is one of the key characteristics of the EI, which enhances the interoperability of different types of energy flows while consequently increases the probability of cascading failures. Therefore it is of great significance to study the multi-energy flow fault diagnosis of the EI to ensure its safe and stable operation as well as the continuous energy supply. This paper introduces the concept of multi-energy flow cascading fault of the EI for the first time. The energy internet framework for multi-energy flow cascading fault diagnosis is firstly proposed, and then characteristics of various energy networks in the EI are analyzed from the perspective of fault diagnosis. Finally, future research prospects are discussed. © 2017 IEEE.

关键词： Failure analysis

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Short-term power Prediction Based on Improved NWP Data Considering Wind Speed Distribution Inner Wind Farm

Short-term Power Prediction Based on Improved NWP Data Consi...

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

作者： Wei Ma Ying Qiao ZongXiang Lu ZhiFeng Liang JiaMing Li YuChen Hao State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments of Electrical Engineering Tsinghua University Beijing China State Grid Corporation of China Beijing China State Grid Jiangsu Power Grid Corporation Nanjing China

The wind farm has only one NWP data point, which cannot accurately reflect the wind resources inside the wind farm. To solve the problem of a poor match between short-term wind power prediction numerical weather forecast and wind farm measured weather. Put forward a kind of based on clustering and temporal characteristics of the modified liters of scale wind power prediction method, first of all, using EOF orthogonal decomposition method to extract the features of each fan, using hierarchical analysis method of the characteristics of the data matrix clustering, and then, each cluster sample selected representative of a fan, using the error transfer characteristic of the NWP data sequence is modified. Finally, The CNN prediction model is used for power prediction, and the weight is determined according to the cluster sample size. A wind farm in northern Hebei, China, is used to verify the effectiveness of the proposed method.

关键词： Fans Wind speed System integration Wind farms Wind power generation Predictive models Feature extraction

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Dynamic emergency control in digital distribution substation with MW PV power

Dynamic emergency control in digital distribution substation...

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International Conference on Critical Infrastructures, CRIS

作者： Bin Wang Tianxiao Huang Xinzhou Dong Bo Jiang Z Q Bo State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China AREV A T & D UK Limited Stafford UK

MW level photovoltaic generation has enough power to support the partial loads in the island operations. But the challenge is how to balance the power supply and load while the power grid is blackout, and the power supply changes to PV power. In response to this question, the anti-islanding strategy is replaced by balancing the PV output and the load shedding in paper to achieve the available maximum power balance in distribution substation. It is achieved by collecting all feeders currents (power supply and feeder outputs), which is realized in the digital substation based on IEC61850. The system scheme and the dynamic emergency control strategy to inverters in PV controller are introduced in paper. The work of the paper is valued to the research on the novel dynamic control scheme in distribution system with DGs.

关键词： Electronic mail Medical services Electric shock

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Analysing on characteristics of lightning shielding failure of UHVAC double circuit transmission line based on leader progression method

Analysing on characteristics of lightning shielding failure ...

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Asia-Pacific Symposium on Electromagnetic Compatibility (APEMC)

作者： Zhiyong Wang Shaoan Wang Zhanqing Yu Yinan Geng Rong Zeng Jinliang He Zhizhao Li Guangzhou Power Supply Bureau China Southern Power Grid Company Limited Guangzhou China Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781424456215

Shielding failure of lightning is the key problem for safe operation of UHV transmission lines. Taking the feature of 1000KV AC double circuit transmission lines into account, the leader progression method with proper criterion was employed. The lightning shielding failure rate of top phase, middle phase and bottom phase of two different transmission line tower types were compute, in three different geography conditions. The research work is helpful for improving the lightning performance of UHV transmission lines.

关键词： Failure analysis Lightning Distributed parameter circuits Conductors power transmission lines Transmission line theory Voltage Corona Poles and towers power system simulation

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