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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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A Novel Method of power Swing Blocking in Impedance Relay 8

A Novel Method of Power Swing Blocking in Impedance Relay

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8th IEEE International Conference on Advanced power System Automation and Protection, APAP 2019

作者： Wang, Hao Kang, Xiaoning Dong, Xinzhou Xi'an Jiaotong University Shaanxi Key Laboratory of Smart Grid Xi'an China Tsinghua University State Key Laboratory of Control and Simulation Power System and Generation Equipment Beijing China

ISBN: (纸本)9781728117225

Distance protection is widely applied in High/Ultra- High Voltage AC transmission system. Impedance relay, the core element of distance protection, may operate incorrectly under power swing, so a power swing blocking unit is needed in distance protection. In this paper, the phase difference between the measurement voltage and compensation voltage under power swing and line fault is analyzed. Based on the analysis, a power swing blocking strategy using the change rate of phase difference between measurement voltage and compensation voltage is proposed. simulation results in PSCAD/EMTDC indicate that the proposed strategy can block the impedance relay reliably under power swing and unblock the impedance relay after detecting the fault under power swing. © 2019 IEEE.

关键词： Electric power system protection

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Steady-state model of multi-port electric energy router and power flow analysis method of AC/DC hybrid system considering control strategies

Steady-state model of multi-port electric energy router and ...

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作者： Shen, Yu Zhu, Fengju Zhang, Chunpeng Cai, Weiqian Yuan, Liqiang Li, Kai Zhao, Zhengming State Key Lab of Control and Simulation Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

This study proposes a steady-state model of multi-port electric energy router (EER) and a power flow analysis method for AC/DC hybrid system considering control strategies. Firstly, a circuit topology model of EER is put forward, including AC and DC port equivalent parts. Secondly, considering external control characteristics of EER, the control strategies including PQ mode, V/f mode, and droop mode are established, which is suitable for system analysis. Then, using the extended sub-network model, an AC/DC power flow model containing multi-port EER is established. In terms of the power flow algorithm for AC/DC hybrid system, AC/DC network admittance matrix and the extended AC/DC network modification equations are applied to solve the problem. Two examples are designed and show that EER can be used for flexible power regulation and voltage improvement. Besides, power flow analysis method of AC/DC hybrid system is demonstrated to be effective. © 2019 Institution of Engineering and *** right reserved.

关键词： Topology

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

arXiv

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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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High impedance fault analysis and location of single-phase-to-ground fault in feeder with multiple DGS connections 8

High impedance fault analysis and location of single-phase-t...

引用

8th Renewable power generation Conference, RPG 2019

作者： Ren, Xuan Wang, Bin Dong, Xinzhou Department of Electrical Engineering Tsinghua University Beijing China Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781839531255

Since the single-terminal fault location in the collection line of wind farm is seriously affected by the complex wind turbine branch, the traditional fault location methods are not applicable to the wind farm anymore. According to the traditional single-terminal impedance fault location method, the zero-fault sequence network of wind farm is studied. Generally, the box transformer is delta-connected to the wind turbine, so when a single-phase-to-ground fault occurs, there is no zero-sequence fault current flowing in the wind turbine branch. Then an improved fault location algorithm for the collection line of wind farm is proposed. In this method, with the wind turbine branch current considered, the collection line of wind farm is divided into several sections, and the fault location is searched step by step after the fault. This method can effectively reduce the influence of wind turbine branch on fault location and the fault distance and the fault resistance can be calculated accurately. Based on PSCAD simulation, the proposed fault location algorithm is validated. © 2019 Institution of Engineering and Technology. All rights reserved.

关键词： Wind turbines

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Measurement-driven AA-CAES Model for Distribution Network Dispatch in Coordination with Renewable generation 4

Measurement-driven AA-CAES Model for Distribution Network Di...

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2020 4th International Conference on Sustainable Energy Engineering, ICSEE 2020

作者： Xie, Yuguang Bai, Jiayu Liu, Dangwu Zheng, Tianwen Mei, Shengwei State Grid Anhui Electric Power Research Institute Hefei230601 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing100084 China State Grid Anhui Electric Power CO. LTD. Hefei230022 China Sichuan Energy Internet Research Institute Tsinghua University Chengdu610213 China

Advanced adiabatic compressed air energy storage (AA-CAES) could play an important role in power distribution system for mitigating the intermittency of distributed renewable generations and reducing the peak-valley difference of load demand, which requires to operate AA-CAES under off-design conditions. A power system dispatch oriented AA-CAES model was proposed based on the technically thermodynamic performance curves of compressor and expansion calibrated from experiments, highlighting the impact of AA-CAES part-lard features on charging/discharging efficiency and capacity. The proposed model is integrated with economic dispatch problem of power distribution systems, giving rise to a nonlinear program due to the state-dependent charging and discharging performances. The dispatch model is further linearized via piecewise linear approximation and special-ordered set of type 2, and its equivalent mixed integer linear formulation is presented. A modified IEEE 33-bus system is adopted to verify the effectiveness of proposed model for renewables accommodation. © Published under licence by IOP Publishing Ltd.

关键词： Scheduling

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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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key technologies of the operational reliability evaluation for the large-scale battery energy storage system 7

Key technologies of the operational reliability evaluation f...

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7th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2019

作者： Cheng, Lin Wan, Yuxiang Jiang, Yi Wang, Zhidong Liu, Mei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing100084 China State Grid Economic and Technological Research Institute Corporation Limited State Grid Corporation of China Beijing102209 China

ISBN: (纸本)9789881532343

The large-scale battery energy storage system (BESS) can effectively meet the diversified needs of power grid dispatching. Therefore, the improvement of the BESS operational reliability is of great significance to ensure the operation safety of the grid. However, the BESS is composed of a large number of batteries. This fact suggests the BESS reliability depends not only on the battery operating state but also on the strategy of battery networking reconfiguration. In this paper, the analysis of the operational reliability research of largescale BESS is carried out in-depth. The research status of reliability of large-scale BESS is investigated, and some thoughts on the obstacles to the BESS operational reliability evaluation are given. The promotion of the new technology of BESS and the development of the ubiquitous Internet of Things on BESS operation reliability are analyzed. In addition, the framework of the operational reliability evaluation of a large-scale BESS is proposed. Some key technologies such as failure mechanism, equipment reliability modeling, evaluation, and optimization are summarized, providing some suggestions for the application of large-scale BESS. © 2019 by International Academic Publishers Ltd.

关键词： Electric batteries

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The Influence of Positive Temperature Coefficient Material on the DC Electric Field within Epoxy Composites

The Influence of Positive Temperature Coefficient Material o...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Chenyuan Teng Yuanxiang Zhou Ling Zhang Yunxiao Zhang Xuewei Wang Zixia Cheng Meng Huang China 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 School of Electrical Engineering Zhengzhou University Zhengzhou China The State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

ISBN: (纸本)9781728195728;9781728195735

Negative temperature (NT) coefficient electrical resistivity of insulating materials causes the distortion of DC electric field, increasing the design and manufacture difficulty of HVDC equipment. The ceramic with positive temperature coefficient (PTC) electrical resistivity was doped into epoxy resin to weaken its temperature dependence of electrical resistivity (0~35 wt%). The electric field and temperature distribution under temperature gradient were simulated. The PTC effect of fillers is able to mitigate the distortion of electric field under temperature gradient, which is through the synergistic optimization of both electrical resistivity-temperature characteristic and thermal conductivity. The optimization of electric field distribution within insulation via BT60/epoxy composites has potential to be used in HVDC electrical equipment.

关键词： Temperature sensors Temperature distribution Temperature dependence Thermal resistance HVDC transmission Conductivity Thermal conductivity

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