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Positive-sequence component based three-phase unbalanced power flow solution for distribution system with PV nodes

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2012年第1期32卷 115-121页

作者： Li, Hongwei Sun, Hongbin Zhang, An'an Liu, Qingyou State Key Laboratory of Oil and Gas Reservoirs Geology and Exploitation Southwest Petroleum University Chengdu 610500 Sichuan Province China State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

The traditional power flow methods aren't appropriate to the electrical distribution systems with distributed generators (DG). Therefore, a direct unbalanced three-phase power flow algorithm was presented in this paper. The proposed approach which was developed based on the path matrix, utilized the special topological structure of distribution systems and established the incident matrix of node voltages and injection currents. Based on the assumption that the positive-sequence voltage magnitudes of PV nodes are invariable, the relation of reactive power and compensation voltage for the PV nodes had been derived by the positivesequence component and path matrix. As a result, a new approach handling PV nodes of DG had been proposed and could be integrated into the proposed power flow method. It needn't introduce any additional active power at PV nodes and kept the positive-sequence voltage magnitudes on their scheduled values, considering that reactive power limits were not violated. The results of the 6-bus and the 69-bus test systems verified the validity and universality of the proposed methods. © 2012 Chin. Soc. for Elec. Eng.

关键词： Reactive power

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INFLUENCES OF BREAKDOWN CHARACTERISTICS OF DISCONNECT SWITCH GAP ON RESIDUAL VOLTAGE

INFLUENCES OF BREAKDOWN CHARACTERISTICS OF DISCONNECT SWITCH...

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The ⅪⅩ International Conference on Gas Discharges and Their Applications

作者： YUE GONGCHANG GUAN YONGGANG LIU WEIDONG CHEN WEIJIANG LI ZHIBING State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical EngineeringTsinghua University State Grid Corporation of China China Electric Power Research Institute

The very fast transient overvoltages(VFTO) are generated during operation of disconnect switch (DS) of gas insulated switchgear(GIS). After the opening operation of DS,the load side busbar is left at a residual *** residual voltage is determined by the opening phase and the breakdown characteristics of SF6 gap of DS. This study obtains the breakdown characteristic of the test DS,including the dielectric strength recovery speed and polarity effect factor of gap of testing *** the stochastic property of DS opening phase,the opening process of DS is simulated by computer under different dielectric strength recovery speeds and polarity effect *** results show that the dielectric strength recovery speed and polarity effect factor have big influences over the residual *** proper value of dielectric strength recovery speed and polarity effect factor could make the residual voltage minor

关键词： simulation INFLUENCES OF BREAKDOWN CHARACTERISTICS OF DISCONNECT SWITCH GAP ON RESIDUAL VOLTAGE

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Frequency dependent network equivalent based electromagnetic and electromechanical decoupled hybrid simulation

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2012年第16期32卷 107-114页

作者： Zhang, Yi Wu, Wenchuan Zhang, Boming Gole, Aniruddha M. State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Department of Electrical and Computer Engineering University of Manitoba Winnipeg R3T 5V6 Canada

Neither electromechanical transient stability analysis (TSA) program nor electromagnetic transient (EMT) programs can be used individually for the transient stability studies of the large scale AC/DC systems. This paper presented an electromagnetic and electromechanical hybrid simulation system, based on a frequency dependent network equivalent. Firstly, the framework and the main modules of the proposed hybrid simulation system were introduced. Secondly, the methods to calculate the equivalents of the electromagnetic side and the electromechanical side were introduced. The discussion on the difference between the traditional method and frequency dependent network equivalent (FDNE) and the flowchart of the hybrid simulation were also given. In the last part of the paper, AC system and AC-DC hybrid system are both used as examples to demonstrate the accuracy of the proposed hybrid simulation system's simulation results. © 2012 Chinese Society for Electrical Engineering.

关键词： Hybrid systems

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Substation switching electromagnetic transient analysis using the time domain integral equation with a high order implicit scheme

Substation switching electromagnetic transient analysis usin...

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IEEE International Symposium on Electromagnetic Compatibility (EMC)

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

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.

关键词： Transient analysis Switches Time domain analysis Wires Integrated circuit modeling Conductors

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An Energy-based Methodology for Locating the Source of Forced Oscillations in power systems

An Energy-based Methodology for Locating the Source of Force...

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IEEE International Conference on power System Technology

作者： Li Ying Shen Chen Liu Feng State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

Recently, several power grids of China came across low frequency oscillations which are difficult to explain by the traditional negative damping mechanism. Some researchers suggest that those oscillations be caused by external periodic disturbances according to the forced oscillation mechanism. It takes no doubt that the oscillation source location (means locating the disturbances) is imperative and decisive to eliminate such a kind of oscillations. This paper proposes a location methodology based on Energy Supply on Port derived from the Port-controlled Hamiltonian theory. By calculating the energy injected to the network at corresponding ports, the oscillation sources can be effectively located, even in complicated systems containing various kinds of control devices such as governors and exciters. Different from the traditional methodology based on eigen-analysis, the proposed methodology is naturally decentralized without the dependency on global measurements. Case studies on the standard 4-machine 2-area system and the IEEE-118 bus system show the effectiveness and efficiency of the proposed methodology.

关键词： Oscillation Source Location Forced Oscillation Port-controlled Hamiltonian Energy Supply on Port

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Experimental research of the upward leader inception from transmission line

Experimental research of the upward leader inception from tr...

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

作者： Zeng, Rong Li, Zhizhao Yu, Zhanqing Zhuang, Chijie State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457714665

Electro-Geometric Model (EGM) has been applied widely all over the world to evaluate the lightning shielding failure of transmission line. But with the increase of operation voltage to 1000 kV and tower height to more than 100 meters, some shortcomings of the traditional EGM model were found by many researchers. Leader Progression Model (LPM) was proposed to solve these problems. But some fundamental works, such as when the upward leader initiates and how it propagates, is still indistinct. An experiment was designed and implemented in this paper to simulate the electric field circumstance near the test transmission line while the lightning downward leader approached. The upward leader from the test transmission line was clearly observed. The inception voltage and characteristics was analyzed. The streamer and leader initiated from the ground wire and conductor bundle were compared. The experiment results show that the leader initiating from the ground wire is more active in the inception stage. The velocity of the upward leader acquired is about 1.2-3.0 cm/μs. © 2011 IEEE.

关键词： Electric lines

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Analyses on frequency transmission characteristic of traveling wave in distribution power system

Analyses on frequency transmission characteristic of traveli...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Wang, Jun Shi, Shenxing Dong, Xinzhou Wang, Bin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

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. © 2011 IEEE.

关键词： Wavelet transforms

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Research on the process of power flow transferring and its identification method

Research on the process of power flow transferring and its i...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Liu, Kun Dong, Xinzhou Wang, Bin Shi, Shenxing State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

This paper analyzes the general process of power flow transferring and divides it into four parts: 1) the process of first phase selection after fault occurs;2) the process of selective action at the first time;3) the process of second phase selection and status confirmation;4) the process after status confirmation. It points out that the issue of asymmetrical flow transferring is a critical process which must be put emphasis on. Then it proposes a method to identify this process, and discuss different solution methods. © 2011 IEEE.

关键词： Electric load flow

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A novel fault locator for power distribution system with neutral non-effectively grounded

A novel fault locator for power distribution system with neu...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Shi, Shenxing Dong, Xinzhou State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

Fault locator for power distribution system with neutral non-effectively grounded should locate phase-to-phase fault and single-phase-to-ground fault respectively. For phase-to-phase fault, the point can be located by power-frequency impedance. However, for single-phase-to-ground fault with limited power-frequency current not more than load current, a novel fault location technology should be developed. The paper will present a practical single-phase-to-ground fault location based on fault generated traveling waves acquired from one phase current transducer and zero sequence current transducer at first. Then implementation of the novel fault locator is proposed including hardware design and software flowchart. At last field tests will be made to verify the feasibility of the fault locator. © 2011 IEEE.

关键词： Transducers

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Single phase grounding fault location based on frequency domain characteristics of fault current

Single phase grounding fault location based on frequency dom...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Jiang, Bo Shi, Shenxing Dong, Xinzhou Wang, Bin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

This paper studies the fault current frequency spectrum characteristics of single phase ground fault in ungrounded distribution networks, and the fault location method based on it. Firstly, it analyzes the production mechanism of 2nd major frequency component, and the relationship between the 2nd major frequency component and series resonance frequency of the faulted line. Secondly, from the perspectives of lumped-parameter circuit, the relationship between 2nd major frequency component and fault location is deduced. simulation cases are used to confirm the relationship. Last, the impact of load and initial fault phase angle on the 2nd major frequency component are researched. simulation research proves the feasibility of the fault detection and location method based on frequency domain characteristics. © 2011 IEEE.

关键词： Electric fault location

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