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Reactive voltage control of bidirectional-interaction coordination between provincial and district power networks with wind power integration

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第24期38卷 48-55页

作者： Wang, Bin Guo, Qinglai Li, Haifeng Sun, Hongbin Tang, Lei Zhang, Boming State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China

An agile and coordinated voltage control method is proposed to deal with the power system reactive power and voltage operation with large scale wind power integration. In the provincial control center, the agile voltage control method with the wind power volatility and the power system N-1 security constraints taken into account is proposed. With this method, by means of the adaptive adjustment of the control period and control model, the wind farm reactive ability will be fully tapped to suppress the influence of wind fluctuations on the bus voltage while sufficient dynamic reactive power regulation margin of traditional generators will be retained. Between provincial and prefectural control centers, the bidirectional interaction based voltage control method is presented to support the voltage at the terminal power network while bypassing the unnecessary discrete device action on the prefectural grid. By coordinated voltage control among the wind farms and substations in the provincial power system, the control abilities of its own wind farms will be made full use of, there will be less capacitor and reactor action times in its own substations and unnecessary reactive power flow. By the bidirectional interaction between provincial and prefectural control centers, the distributed adjustment resources can well be used to support the voltage at the terminal power network and increase the safety and economy of overall operation of the power system. The wind automatic voltage control system is currently in real-time operation in Jiangsu power system. © 2014 state Grid Electric power Research Institute Press.

关键词： Voltage control

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Secondary voltage control considering rapid dynamic reactive power compensation

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Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第2期39卷 53-60页

作者： Wang, Xuran Guo, Qinglai Sun, Hongbin Wang, Bin Zhang, Mingye Zhang, Boming Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China

This paper presents a secondary voltage control system considering rapid dynamic var compensators, such as static var compensator/static synchronous compensator (SVC/STATCOM). In order to take full advantage of the rapid adjustment feature of SVC/STATCOM in static voltage control and transient voltage stability, two independent control stages are dealt with. In the first stage, SVC/STATCOM and conventional var compensators are incorporated in the coordinate secondary voltage control model to bring the rapid adjustment feature of SVC/STATCOM into full play. In the second stage, a quadratic programming model is designed to do the optimal control of the dynamic reactive power reserves. The reactive power compensation of the slow dynamic var compensators is substituted for that of SVC/STATCOM, and the dynamic reactive power reserves level is improved. Through coordination between sequence and space, all kinds of reactive power compensators are made full use of in the secondary voltage control and transient voltage stability prevention control. Nordic system test results show that the system can greatly improve the response speed of traditional secondary voltage control while avoiding the conflict between SVC/STATCOM and the traditional reactive power compensators. At the same time, the system is able to carry out effective preventive control of transient voltage stability and improve the recovery effect of system voltage after the disturbance. ©, 2015 state Grid Electric power Research Institute Press.

关键词： Reactive power

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Research on surface electric field of parallel gap

Research on surface electric field of parallel gap

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2011 7th Asia-Pacific International Conference on Lightning, APL2011

作者： Yu, Junjie Yu, Zhanqing Zeng, Rong Chen, He Peng, Xiang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China Maintenance and Test Center of EHV Power Transmission Company China Southern Power Grid Co. Ltd. Guangzhou 510663 China

ISBN: (纸本)9781457714665

With parallel gap, by controlling the motion path of the electric arc, effectively avoid burning and damaging the insulator during lightning strike so that the effect to reduce the accident rate of line is obvious. Because of simple structure, convenient installation and good economical efficiency, its importance in measures of lightning protection for transmitting line is continually improved. Electric field characteristics on the surface of parallel gap electrode have obvious influence on corona generation and the gap breakdown position and are the key parameters that must be considered in the design. Based on the finite element method, this paper sets up the analysis model of electric field of parallel gap including the tower, the conductor and the insulator, uses ANSOFT software for simulation, studies the surface electric field characteristics of parallel gap electrode, compares the electric field of four types of parallel gap put forward in the paper and analyzes the law of influence of parallel gap electrode parameters on the electric field characteristics. The results show that, when the short circuit distance is increased, the maximum values of electric field of ball end and snap ring body are obviously increased;the opening angle of snap ring is larger and the maximum value of electric field of ball end is higher;when the pipe diameter is increased, the maximum value of electric field of snap ring body is reduced considerably;the ball end is bigger and the maximum value of electric field of ball end is less;the ring pipe diameter is the structure parameter having the largest influence on the surface electric field;for the ball end at the end of ring electrode, the structure parameter having the largest influence on the electric field is the diameter of ball end. Reducing the distance that the ball end stands out of the ring plane can decrease the maximum value of electric field of ball end. © 2011 IEEE.

关键词： Finite element method

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

作者： Yan, Weihang Gao, David Wenzhong Zhang, Fang Cheng, Lin Yan, Shijie Department of Electrical and Computer Engineering University of Denver Denver United States 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)9781538614273

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. © 2017 IEEE.

关键词： Dynamics

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Grid dispatch model and interconnection benefit analysis of concentrating solar power plants with thermal storage

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第19期38卷 1-7页

作者： Chen, Runze Sun, Hongbin Li, Zhengshuo Liu, Yibing Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China

Nowadays, the concentrating solar power (CSP) plant with thermal storage is a new way to utilize solar power. By making full use of large-capacity CSP devices, the CSP system is able to translate the solar power absorbed. Additionally, the CSP generates power via a steam turbo-generator and has fast regulating performance. The operation behavior of CSP is studied from the viewpoint of power grid, based on which its mathematical model for dispatch is developed. The model describes the power flow inside the CSP with its major operation constraints. Furthermore, the model for power system dispatch considering CSP plants is built based on the security-constrained unit commitment problem. It is shown by simulation that CSP, on the premise of its energy being fully accommodated, may bring about considerable benefits to the power system by reducing the generation cost, increasing renewable energy accommodation and enhancing utilization of transmission lines. © 2014 state Grid Electric power Research Institute Press.

关键词： Concentrated solar power

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Optimal controller Design for Non-Affine Nonlinear power systems with Static Var Compensators for Hybrid UAVs

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Tsinghua Science and Technology 2022年第1期27卷 196-206页

作者： Yanchu Li Qingqing Ding Shufang Li Stanimir Valtchev Beijing Key Laboratory of Network System Architecture and Convergence Beijing Laboratory of Advanced Information Networkand School of Information&Communication EngineeringBeijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua UniversityBeijing 100084China the Nova School of Science and Technology(FCT/UNL) Caparica 2829-516LisbonPortugal Technical University of Sofia(TUS) Sofia 2125Bulgaria

A generalized non-affine nonlinear power system model is presented for a single machine bus power system with a Static Var Compensator(SVC)or state Var System(SVS)for hybrid Unmanned Aerial Vehicles(UAVs).The model is constructed by differential algebraic equations on the MATLAB-Simulink platform with the programming technique of its *** the inverse system method and the Linear Quadratic Regulation(LQR),an optimized SVC controller is *** simulations under three fault conditions show that the proposed controller can effectively improve the power system transient performance.

关键词： Static Var Compensator(SVC) Unmanned Aerial Vehicles(UAV) power system non-affine nonlinear control inverse system method Linear Quadratic Regulation(LQR)

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Analysis of Excitation Characteristics of Ultra High Frequency Electromagnetic Waves Induced by PD in GIS

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高电压技术 2013年第8期39卷 1893-1901页

作者： DING Dengwei GAO Wensheng YAO Senjing LIU Weidong HE Jiaxi Sichuan Electric Power Research Institute Chengdu 610072 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Shenzhen Power Supply Co. Ltd Shenzhen 518001 China

The understanding of the excitation mechanism of ultra high frequency (UHF) electromagnetic waves (EW) is essential for ap- plying UHF method to partial discharge (PD) detection. Since the EW induced by PD in gas insulated switchgear (GIS) contains not only transverse electromagnetic (TEM) wave, but also high-order transverse electric (TE) and high-order transverse magnetic (TM) waves, we analyzed the proportions between the TEM wave and the high order waves, as well as the influence of the PD position on this proportion, using the finite different time domain (FDTD) method. According to the unique characteristics of the waves, they are separated only ap- proximately. It is found that the high-order mode is the main component, more than 70%, of the electric field around the enclosure of GIS, and that with the increasing distance between PD source and inner conductors, the low frequency ( below about 800 MHz) component of EW decreases, but the high frequency component (above 1 GHz) increases, meanwhile the proportion of high-order components in EW could reach 77% from 70%. It concluded that the closer the PD source to the enclosure is, the easier high order EW may be excited.

关键词：超高频电磁波励磁特性 GIS PD 诱导气体绝缘开关设备 UHF方法 TEM波

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Travelling wave based single phase grounding protection for distribution system

Travelling wave based single phase grounding protection for ...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Dong, Xinzhou Wang, Jun Shi, Shenxing Wang, Bin Dominik, Bak Kirby, Brian Yang, Xia State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China Alstom Grid Stafford ST174LX United Kingdom

ISBN: (纸本)9781849198349

It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is proposed in the paper. The polarity of initial transient current and voltage travelling waves are used to identify the fault direction, and power frequency voltages are used to distinguish SFG from phaseto- phase fault to ensure the reliability of the protection. In the paper, wavelet transforms and module maxima theory was adopted to represent the polarity of travelling waves effectively and construct protection algorithm,. The analysis and simulation demonstrate that the protection is valid.

关键词： Wavelet transforms

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Optimal reactive power compensation configuration in distribution power system integrated with small hydro power plant

Optimal reactive power compensation configuration in distrib...

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3rd International Conference on Energy and Environmental Protection, ICEEP 2014

作者： Ma, Hong Liang Ren, Zheng Mou Lu, Wen Xin Han, Yu Xin Wang, Zhao Jian Chen, Lai Jun Shaanxi Regional Electric Power Group Co. Ltd Xi'an 710061 China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University 100084 Beijing China

ISBN: (纸本)9783038351368

Hydropower is the most widely used renewable energy for electricity generation in China, and small hydro power plant (SHPP) is a flexible way of electricity generation in water-rich remote area. Voltage at the end of distribution network may be increased over the acceptable range due to the connection of SHPPs. Magnetic control reactor (MCR) is usually used to reduce the voltage by consuming reactive power. A mathematical model for calculation of the optimal capacity of MCR is proposed in this paper, and particle swarm optimization (PSO) is adopted to solve the optimization problem. Two cases based on the IEEE 33-bus test system are used to validate the proposed method. In the given cases, system voltage is adjusted to the acceptable range. © (2014) Trans Tech Publications, Switzerland.

关键词： Reactive power

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Failure analysis of fan mill in thermal power plant 68

Failure analysis of fan mill in thermal power plant

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68th Society for Machinery Failure Prevention Technology Conference: Technology Solutions for Affordable Sustainment, MFPT 2014

作者： Liu, Chao Jiang, Dongxiang Chu, Fulei Department of Mechanical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

Fan mill is an important device in thermal plants, which supply coal power to boiler. Crack failures recently occurred in pulverizing wheels of fan mills in a power plant in China. The cracks happens in quite a few pulverizing wheels and they affect the normal operation. To find out the root cause of the cracks, Finite Element Analysis (FEA) of the pulverizing wheel is carried out in this work. The assembly with real dimensions is modelled to calculate the concentrated stress and strain with centrifugal load, driving load, and operational temperature taken into account. Contact effects are included in the finite element model as well as nonlinear material property. Based on the analysis, the crack causes are determined: (i) the initial stress exceeds the yield limit in normal operational condition, resulting low safety coefficient;(ii) the stress increases significantly in the worn pulverizing wheel, where the risk of failure is greatly increased.

关键词： Cracks

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