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Substation-dispatch center two-level distributed state estimation

Dianli Xitong Zidonghua/Automation of Electric power systems 2012年第7期36卷 44-50+91页

作者： Li, Qingxin Sun, Hongbin Wang, Jing Zhang, Boming Wu, Wenchuan Guo, Qinglai State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

A two-level distributed state estimation method for substation-dispatch center is proposed. After zero impedance three-phase state estimation based on KCL has been applied in substation, up load ripe data are treated in dispatch center level and the single-phase state estimation for all grid implemented. The detailed discussions about the architecture, algorithm, ripe data transmission, time setting and period selection, transmission protocol and transition scheme for the method are given. The results of calculation example show that this method is in favor of simultaneously identifying three-phase bad data and topology error, reducing communication burden, and increasing the reliability of the dispatch center state estimation for all grid. © 2012 State Grid Electric power Research Institute Press.

关键词： State estimation

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The bandwidth of instrument current transformer for fault detection in distribution networks

The bandwidth of instrument current transformer for fault de...

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

作者： Jiang, Bo Dong, Xinzhou Shi, Shenxing Wang, Bin Bak, Dominik 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)9781849198349

The distribution network detection devices are generally using two kinds of instrument current transformer (ICT), of which one is used to transform the travelling wave and transient signals, while the other is used to transform the power frequency signals. Such scheme is neither necessary nor economical. This paper analyses the influences of sampling resistance, stray capacitance and magnetizing inductance on the frequency characteristic of ICT. Considering that fault zero sequence transient current has big transient component and small power frequency component, an ICT with wide band frequency accuracy has been chosen. Practical experiments have been done. The technical parameters given by the instrument factory are only within 20-20kHz. The characteristics in higher frequency are seldom reported due to the lack of test means. The experiments in this paper is based on the transient tester instrument and current amplifiers developed by our lab.ratory, which can output wide frequency band current within 20Hz-100kHz up to 50A. Experiment shows that, the predicted results were in good agreement with the measured ones.

关键词： Electric instrument transformers

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High impedance fault detection on distribution systems with harmonic interference in wind farms 13

High impedance fault detection on distribution systems with ...

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13th International Conference on Development in power System Protection 2016, DPSP 2016

作者： Ni, Jiang Wang, Bin Dong, Xinzhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China

ISBN: (纸本)9781785618260

High impedance faults (HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse due to the limited fault current values and the situation is worse in wind farms. The mostly adopted HIF detection algorithms are based on the 3rd harmonic characteristic of the fault zero-sequence currents, whereas these 3rd harmonics are very easy to be polluted by wind power back-to-back converters. To solve this problem, the typical HIF arc flash based on Mayr's arc model is first built, and the typical fault waveforms of HIF in wind farm are presented. Then the characteristics of high impedance faults are analysed to distinguish the occurrence of HIF from other harmonic interference. After that, the performance of the traditional harmonic based HIF detection algorithm is discussed, and a novel detection algorithm is presented to prevent harmonic interference influence in wind farms.

关键词： Electric utilities

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Effects of temperature on creepage discharge characteristics in oil-impregnated pressboard insulation under combined AC–DC voltage

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Plasma Science and Technology 2019年第5期21卷 14-22页

作者： Fubao JIN Yuanxiang ZHOU Bin LIANG Zhongliu ZHOU Ling ZHANG Key Laboratory of Plateau Ecology and Agriculture College of Agriculture and Animal HusbandrySchool of Water Resources and Electric PowerQinghai UniversityXining 800016People's Republic of China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084People's Republic of China

Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard(OIP) of the converter transformer are different from those of the traditional AC transformer. The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC–DC voltage is seriously inadequate. Therefore, this paper investigates the characteristics of OIP creepage discharge under combined AC–DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70 °C to 110 °C. The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature. The times of low amplitude discharge(LAD) decrease and amplitude of LAD increases. Simultaneously, the times of high amplitude discharge(HAD) gradually increase at each stage of creepage discharge with higher temperature. The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging. The residual charge carriers are more easily dissipated after *** ‘hump’ region of LAD moves to the direction of higher discharge magnitude. The interval time between two continuous discharges is shortened obviously. The concentration of HAD accelerates the development of OIP insulation creepage discharge. The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage.

关键词： oil-impregnated pressboard insulation combined AC-DC voltage inception voltage creepage discharge temperature flashover voltage

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A VCG Payment Scheme for Energy Storages in the Spot Market Considering Levelized-Cost-of-Storage 8

A VCG Payment Scheme for Energy Storages in the Spot Market ...

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8th Asia Conference on power and Electrical Engineering, ACPEE 2023

作者： Liu, Jianing Zhao, Yue Su, Zhuo Wang, Ke He, Yujun Guangdong Province Power Grid Co. Ltd Power Dispatching and Control Center Guangzhou China Tsinghua Univeristy State Key Lab of Control and Simulation of Power Systems and Generation Equipments Beijing China

ISBN: (纸本)9798350345520

Energy storages are considered as a key solution in the novel energy system with high penetration of renewables. However, the current power markets are not designed for the participation of energy storage as it has a variable cost. This paper investigates an efficient mechanism in which the energy storage submits his levelized cost of storage, then the storage receives a Vickrey-Clark-Grove payment equal to the increase in social welfare attributable to his presence. This mechanism can encourage the storage to truthfully submit the true operating cost and thus help to optimize the system operation. Moreover, the increments of the storage's own interests and the social welfare are coincidental, so it is incentive compatible. Numerical tests show the advantages of the proposed mechanism over the marginal pricing mechanism. © 2023 IEEE.

关键词： Energy storage

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Blackout Risk Analysis and control of power System Integrated with Wind Farm 28

Blackout Risk Analysis and Control of Power System Integrate...

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第28届中国控制与决策会议

作者： Zhong Yuxin Zhang Xuemin Mei Shengwei Xia Deming Wang Shuai Shi Rui Dept.of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation EquipmentsTsinghua University Northeast Branch of State Grid Corporation of China State Power Economic Research Institute

ISBN: (纸本)9781467397155

With the increase of wind power penetration,the characteristics of the wind farm have brought a significant impact on the security of power *** is urgent to study how to reduce the risk of cascading failures while improving the environmental *** this paper,a cascading failure model containing wind farm is proposed,which considers wind power characteristics,such as the structure of wind farm,the randomness of power of wind farm,the virtual inertia control of wind turbine,and the disconnection response of wind turbine after short-circuit *** order to identify the key factors of blackout,decision tree is used to analyze results generated from this blackout *** control is adopted to decrease the probability or effect of critical attributes that can be found in decision *** blackout risk of IEEE 30 test system integrated with wind farm is *** key factors,such as disconnection of wind turbines from the grid and certain transmission lines,are identified by decision ***,the effectiveness of the virtual inertial control of wind turbine,reactive power compensation and line construction is verified by simulation.

关键词： Wind Farm Disconnection of Wind Turbines Virtual Inertial control Blackout Risk Decision Tree

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Fault location method for high-voltage direct current transmission line using incident current travelling waves

Fault location method for high-voltage direct current transm...

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作者： Wang, Bin Yang, Lin Dong, Xinzhou Department of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing10084 China

The reflection coefficient of the travelling wave is different with different frequencies because of the inductance and capacitive elements on the boundary of the DC transmission line, which leads to the oscillation of the travelling wave. It is difficult to obtain the wave head's arrival time accurately using travelling wave method to locate fault because of the oscillation. The current travelling wave is the superposition of the incident current travelling wave and the reflected current travelling wave. There is no oscillation in the incident wave. Therefore, a method using incident current wave for fault location is proposed here. The initial current travelling wave and the transmission line boundary function are used to calculate the incident current travelling wave, and the incident wave is used to locate fault. The Prony decomposition algorithm is used to identify boundary function using the initial current travelling wave generated in specific fault condition. PSCAD simulation shows that the influence of oscillations of travelling wave can be eliminated by using incident current wave to locate faults, and the accuracy of fault location is improved. © Institution of Engineering and Technology. All rights reserved.

关键词： Electric lines

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Rule Extraction in Transient Stability Study Using Linear Decision Trees

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中国电机工程学报 2011年第34期31卷 I0006-I0006页

作者： SUN Hongbin WANG Kang ZHANG Boming ZHAO Feng State Key Lab of Control and Simulation of Power Systems and Generation Equipments （Dept. of Electrical Engineering Tsinghua University） Haidian District Beijing 100084 China

Traditional operation rules depend on human experience, which are relatively fixed and difficult to fulfill the new demand of the modern power grid. In order to formulate suitable and quickly refreshed operation rules, a method of linear decision tree based on support samples is proposed for rule extraction in this paper. The operation rules extracted by this method have advantages of refinement and intelligence, which helps the dispatching center meet the requirement of smart grid construction.

关键词：英文摘要内容介绍编辑工作期刊

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Breakdown phenomena caused by electrical tree degradation in high density polyethylene under high frequency voltage

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Gaodianya Jishu/High Voltage Engineering 2007年第12期33卷 14-18页

作者： Zhou, Yuan-Xiang Xing, Xiao-Liang Nie, Qiong Wang, Yun-Shan Wang, Ning-Hua Liang, Xi-Dong Guan, Zhi-Cheng State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

The shape change of electrical tree propagating in ice-water quenched high-density polyethylene (HDPE) film under AC voltage of different frequency ranging from 50 Hz to 90 kHz as well as the breakdown phenomena caused by the treeing degradation under high frequency condition were studied. The electrical treeing aging experiment is carried out at room temperature. The shape change of electrical tree and the arcing process during the experiment is observed via a digital micro-observing system. It is found that the arcing process can be obviously observed under a high frequency voltage compared with that under low frequency voltage. It is also found that under different frequency voltages the electrical tree initiation shape is different. Most of the electrical trees are branch-shape tree under lower frequency voltage. When the frequency is higher than 5 kHz, trunk-shape tree and bosk-like tree appears. Once the frequency is higher than 50 kHz, breakdown tree can be found out. It is shown that the tree shape conversion is influenced by the frequency. The electrical tree usually has a simple shape and rarely changes under low frequency voltage in one hour or more. However, under a high frequency voltage, the electrical tree shape changes more frequently and has a large probability to breakdown. The influence of frequency on material polarization process, fatigue and thermo effect is considered as the main causes of the experiment results. The more serious destruction caused by high frequency electrical treeing degradation can well explain the reason of insulation premature inactivation in mid-frequency or high-frequency electrical equipment.

关键词：聚乙烯树老化电树形态转换击穿频率

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Modeling and simulation analysis of dual-rotor vibration system with multiple faults

Modeling and simulation analysis of dual-rotor vibration sys...

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Society for Machinery Failure Prevention Technology Conference 2018: Intelligent Technologies for Equipment and Human Performance Monitoring, MFPT 2018

作者： Yang, Yizhou Liu, Chao Jiang, Dongxiang Yang, Wenguang State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing100084 China

Dual-rotor system is an important rotor form in rotating machinery like gas turbine engine. Its complex structure results in rich dynamical behaviors and more probability to failure. The modeling and simulation of the dual-rotor system can help to understand its dynamic characteristics and provide theoretical support for the design, operation and maintenance. In this paper, a dynamic model of a dual-rotor system with multiple rotor faults is established. The dual-rotor vibration model without any fault is built by finite element method, where the two shafts are connected by an inter-shaft bearing and nonlinear models of rolling element bearing and squeeze film damper are considered. The numerical integration method of Newmark-β is used to obtain the steady-state vibration response of the system. Then rotor faults are introduced to the system model, including unbalance, misalignment, looseness and rub-impact. The steady-state responses of single faults in the dual-rotor system are analyzed and typical fault features are obtained. Then coupling characteristics between different rotor faults, and the influences of the squeeze film dampers on the dynamic characteristics and fault features of the system are studied. © 2018 Proceedings of the 9th International Symposium on Imprecise Probability.

关键词： Rotating machinery

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