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2012 IEEE International Symposium on Electromagnetic Compatibility, EMC 2012

作者： Xiang, Hongjun Chang, Sughun Zou, Jun Heng Yuan, Jians Shenderey, Sergey V. State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Electrical Environment Group Korea Electrotechnology Research Institute Changwon 641600 Korea Republic of

ISBN: (纸本)9781467320610

A fast electric field integral in time domain using the uneven discretization and the implicit scheme is proposed to calculate the switching electromagnetic transient at a substation. The switching transient currents and the resultant radiated electromagnetic field are calculated. The propose d approach has the strength to model the bus system at a substation with a more complicated and realistic configuration that is difficult to simulate using the circuit-based method, because all the electromagnetic couplings within the bus system are included globally. The proposed method might be one of good candidates to predicate the EMI level at a substation. © 2012 IEEE.

关键词： Electric fields

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The large-size low-stray-parameter planar bus bar for high power IGBT-based inverters

The large-size low-stray-parameter planar bus bar for high p...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Liqiang Yuan Hualong Yu Xuesong Wang Zhengming Zhao Ting Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

The large-size planar DC bus bar is widely used in high power converters, whose stray parameters are significantly affected the converter reliability and performance. Taking the example of an actual 315kW/400V inverter, the design, simulation and analysis for its bus bar stray parameters is described in detailed. Being different from the conventional method that considers the bus bar conductor as an entirety, an improved method is proposed in this paper, which separates the bus bar into several segments and evaluates the influence of stray parameters in each segment to the power semiconductor devices respectively. Therefore, this improved method can provide support for the more accurate and effective design and optimization of bus bar. In addition, two different structure of bus bar are implemented in the actual inverter, the comparison and analysis of experiment results for both structures proves the validity of the proposed method.

关键词： Inverters Insulated gate bipolar transistors Equivalent circuits Integrated circuit modeling Inductance Conductors Snubbers

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A schedule power flow auto generating technology in day-ahead security validation

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Dianli Xitong Zidonghua/Automation of Electric power systems 2012年第20期36卷 68-73页

作者： Lin, Yi Sun, Hongbin Wu, Wenchuan Yu, Jun Zhang, Boming State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China National Electric Power Dispatching and Communication Center Beijing 100031 China

Formulation of day-ahead operation schedule for large-scale power grid requires security validation, including static security, dynamic and transient stability. It is an important and basic task for day-ahead security validation to generate an AC power flow that satisfies the demand of the schedule. A new method of generating the day-ahead schedule power flow is proposed, which consists in dividing the problem into two subproblems-the active subproblem and the reactive subproblem. The inconsistency of various kinds of schedule data is coordinated by solving the active subproblem, while a rational voltage distribution is achieved by solving the reactive subproblem. Both of the two problems are formulated as optimization models with constraints satisfied and are solved with an interior point algorithm. Numerical test results on the testing system and real power systems show that the method is capable of providing rational day-ahead schedule power flow. © 2012 State Grid Electric power Research Institute Press.

关键词： Numerical methods

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Equivalent capacity of the lower voltage ride through for wind farm from overcurrent protection in power collection lines

Equivalent capacity of the lower voltage ride through for wi...

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11th IET International Conference on Developments in power systems Protection, DPSP 2012

作者： Wang, Bin Dong, Xinzhou Bo, Zhiqian State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Alstom Grid Stafford ST17 4LX United Kingdom

ISBN: (纸本)9781849196208

Magnitude and duration of voltage sags are the most important two factors to the Lower Voltage Ride Through (LVRT) capacity of the wind generator. Since most voltage sags are caused by the system faults, and sag durations are controlled by the tripping time of overcurrent relay in power collection lines based on the sags' magnitude. The specification of the LVRT capacity of wind generator is introduced into the operation characteristics of the relay in power collection lines. The evaluation model of equivalent LVRT capacity to overcurrent protection is proposed in paper, and the equivalent LVRT capacities from zone I and zone II relay are quantified. Improvement measures are also proposed.

关键词： Overcurrent protection

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power Losses in Two- and Three-Level Three Phase Photovoltaic Inverters Equipped with IGBTs

Power Losses in Two- and Three-Level Three Phase Photovoltai...

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International Conference on Electrical Machines and systems

作者： Zhiping Chen Liqiang Yuan Zhengming Zhao Xiaoying Sun State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University

ISBN: (纸本)9781467323277

To increase efficiency is an essential target in photovoltaic (PV) power generation system. The losses of the whole system consist of several parts. This paper focuses on the losses of the hard-switching devices. An improved method to calculate the device losses is proposed. And influences of different factors like DC link voltage, input power, switching frequency and power factor on the losses are considered. Then this paper compares the losses of conventional two-level inverter and of diode-clamped three-level inverter to provide the evaluation of power losses under different working conditions. This is helpful to design and optimize a certain PV inverter. Calculating results based on an actual three phase 10kW PV inverter are presented.

关键词： Loss-calculation IGBT Three-level Photovoltaic

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power transformer condition assessment by on-line monitoring and trend analysis

Power transformer condition assessment by on-line monitoring...

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IASTED International Conference on power and Energy systems and Applications, PESA 2012

作者： Xie, Qijia Gao, Shengyou Zhang, Hailong Dai, Wen Ruan, Ling Nie, Dexin Lu, Wenhua Key Laboratory of High-Voltage Field-Test Technique of SGCC Hubei Electric Power Testing and Research Institute Wuhan China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China State Grid Electric Power Research Institute Wuhan China School of Electrical Engineering Wuhan University Wuhan China

power transformer condition assessment is the basi of condition-based maintenance and plays a very important role in carrying assets management and risk assessment for power system. As the heart of transmission and transformation system, power transformer's condition has close relation with many factors, such as the production quality of itself, operation environment and so on. This paper analyzes some variables which could represent the transformer's condition, including the data from preventative test, factory test and commission test, diagnostic test, on-line detection and monitoring, routine inspection, operation history, family defection and environment information. Some parameters which have representation are chosen as the condition variables. Artificial neuron network (ANN) and Dempster-Shafer (D-S) evidence theory are adopted to form the multiparameter information fusion condition assessment model. Besides the static value, the change trends of some parameters are considered as an independent evidence section. Cooperating with on-line monitoring, it will be helpful to improve the accuracy and efficiency of condition assessment.

关键词： power transformers

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Multi-source information based current matching state estimation for distribution network

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Dianli Xitong Zidonghua/Automation of Electric power systems 2012年第16期36卷 53-57页

作者： Ju, Yuntao Wu, Wenchuan Cheng, Xueqi Zhang, Boming Sun, Hongbin State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China Weifang Power Supply Bureau Shandong Provincial Power Corporation Weifang 261000 China

By taking into account the real-time measurement with low redundancy and of only partial current in distribution systems and referring to the quasi-real-time current measuring data of the metering system, the current matching technique is proposed to solve the distribution network state estimation. The matching current equations in the sense of optimal estimation and its systematic solution are deduced. Based on the assumption that the load power factor is stable, a quasi-real-time measurement generating method is proposed for loads. With boundaries demarcated by real-time current measurement, the distributed network is divided into several measured areas and current matching state estimation is made for each area. Numerical tests and results of an actual system show that the method proposed can satisfy the real-time application demand of the distribution system. ©2012 State Grid Electric power Research Institute Press.

关键词： State estimation

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EQUIVALENT CAPACITY OF THE LOWER VOLTAGE RIDE THROUGH FOR WIND FARM FROM OVERCURRENT PROTECTION IN power COLLECTION LINES

EQUIVALENT CAPACITY OF THE LOWER VOLTAGE RIDE THROUGH FOR WI...

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IET International Conference on Developments in power System Protection

作者： Bin Wang Xinzhou Dong Zhiqian Bo State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Alstom Grid

ISBN: (纸本)9781622761050

关键词： Wind Farm Lower Voltage Ride Through Overcurrent Protection power collection lines

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Application and benefit analysis of substation state estimation

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Dianli Xitong Baohu yu Kongzhi/power System Protection and control 2012年第12期40卷 56-61页

作者： Li, Qing-Xin Wang, De-Xing Sun, Hong-Bin Wu, Wen-Chuan Wang, Jing Guo, Qing-Lai Zhang, Bo-Ming State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China East China Electric Power Dispatch and Control Sub-Center East China Grid Company Limited Shanghai 200002 China

A substation three-phase nonlinear state estimation method based on zero impedance branches helps to identify topology and analogy errors at substation level and accordingly enhances the control center's state estimation reliability and accuracy. Some issues during the practical implementation process of the technology are reported, such as the hardware configuration, measurement integration, the communication between substation and control center, time setting and period selection. The benefits of the proposed technology have also been analyzed. It is shown that this technology has high reliability and low burden on communication, and improves the ability of monitoring of power grids and the reliability of the real-time power network model significantly. The proposed technology is verified effective by both simulation experiments and field-site applications in East China power Grid, and is well qualified for real-time online applications, which has broad popularization and application prospects.

关键词： State estimation

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A comprehensive rule based method for substation topology error identification

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Dianwang Jishu/power System Technology 2012年第5期36卷 166-172页

作者： Wang, Jing Ge, Minhui Sun, Hongbin Li, Qingxin Wu, Wenchuan Guo, Qinglai Zhang, Boming State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China East China Electric Power Dispatch and Control Sub-Center East China Grid Company Limited Huangpu District Shanghai 200002 China

A substation topology error identification method based on comprehensive rules, including rules in different spatial scales such as element level, bay level and voltage level as well as rules in time sequence, is presented. Utilizing the superiority in multi-source, redundancy and rapid measurement in the substation, the multi spatial scale relevant rules of element, bay and voltage level as well as multi time sequence rules are proposed, and concrete implementation approach for such a method is given. The proposed method can improve the ability to identify the topology error, especially ability to identify switches without analog measurement, thus more reliable topological structure can be provided to control centre to improve the reliability of state estimation for the whole power system. Results of simulation and practical application show that the proposed method is effective.

关键词： Topology

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