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Rotor End Factors for 2-D FEA of Induction Motors with Smooth or Slitted Solid Rotor

CES Transactions on Electrical Machines and systems 2017年第2期1卷 132-139页

作者： Shanming Wang Ziguo Huang Yuguang Sun Haixiang Cao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Modifying the equivalent rotor resistivity with rotor end factor in 2-dimension(2-D)finite element analysis(FEA)is an effective way to analyze the 3-dimension(3-D)solid rotor *** the smooth solid rotor,five different rotor end factors are discussed and compared with each *** is theoretically clarified that the resistivity of rotor in 2-D FEA should be multiplied by the square of rotor end factors to take the 3-D end effect of solid rotor into *** the slitted solid rotor,an improved rotor end factor is proposed based on the equivalent area algorithm of eddy currents in rotor,since the end factors of smooth solid rotor are not ***,the time-harmonic finite element method(FEM)combined with the rotor end factor is applied to analyze the performance of solid rotor induction *** tested and computed results are in good agreement,which proves the effectiveness of rotor end factor for the simplication of 3-D solid rotor problems.

关键词： Eddy currents FEA rotor end factor solid rotor time-harmonic field

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Evaluation of cascading failure in power system based on the operational reliability theory

Evaluation of cascading failure in power system based on the...

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International Conference on Probabilistic Methods Applied to power systems (PMAPS)

作者： Xin Zou Lin Cheng Yuanzhang Sun State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781424457205;9781424457212

According to the characteristics of the cascading failures in power grid, a lot of assessment methods based on the probability theory have been proposed in recent years. However, most of them ignore the influence of the changing operating conditions on the power system planning and operation. This paper assesses the risk of the cascading failure in the power system based on the operational reliability theory which considering the variation of operating states and environment of the power system. The operational reliability of the power system is calculated based on Markov Process which describes the transient probability of states. The key conception of this theory is that the failure rate and the probability of components are changing along with the life of the equipment, the operating states and the environment conditions. A new evaluation procedure is brought up to calculate the operational reliability indices which can provide the specific information of the cascading failure. The evaluating results of the test system confirm that this approach is applicable to analyze the cascading failures in real power system.

关键词： power system faults power system protection power system reliability Reliability theory power system planning power system transients power grids Markov processes Probability System testing

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Optimized design of main protection configuration scheme for internal faults of Shawan generator

Optimized design of main protection configuration scheme for...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Yuguang Sun Xiangheng Wang Lin Gui Weijian Wang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)7506274078

In order to provide high-quality protection for large- and medium-sized generators, a new feasible method of designing main protection configuration scheme for internal faults of generators is desirable. Based on calculation of all the possible internal faults with the multi-loop method, the optimized design method is illustrated through Shawan generator in this paper. With this method, the optimal protection configuration scheme, composed of the split-phase transverse differential protection, two sets of incomplete longitudinal differential protection as well as one set of single element transverse differential protection, is determined for the internal faults of Shawan generator, which has two branches in each phase. The rate of operation and double-protection of the optimal scheme both reach the maximum. In addition to that, on all the possible phase-to-phase faults, at least two kinds of protection of the optimal scheme are sure to operate correctly. The optimized scheme excels the conventional one in protection performance index, which verifies the validity of the optimized method of designing main protection configuration scheme for generators.

关键词： Design optimization Circuit faults Design methodology power generation power system protection Character generation power system simulation Performance analysis Stators Sun

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Ultra-short-term solar power forecasting based on a modified clear sky model

Ultra-short-term solar power forecasting based on a modified...

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Chinese control Conference (CCC)

作者： Yuan Ma Xuemin Zhang Shengwei Mei Zhao Zhen Rui Gao Zijie Zhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9789881563903

ISBN: (纸本)9781728165233

The ultra-short-term prediction of photovoltaic power system is of great significance to the safe operation of power system. However, the daily and annual periodicity of solar radiation brings strong non-stationary to the photovoltaic power series, which makes it difficult to predict the photovoltaic power series. In order to overcome the problem that the detailed clear sky model relies on a large number of plant parameters, this paper proposes a prediction algorithm based on a modified clear sky model. Firstly, historical data and geographical location of a certain site are utilized to build a modified clear sky model, then the theoretical clear sky power curve fitted by the modified clear sky model are divided by the actual historical power output to get a stabilized time series, finally the method of "online update" is adopted to forecast PV plant power output in the ultra-short-term time horizon (0-4 h). The test results of a photovoltaic power station in Ningxia show that the proposed model can reduce the prediction error of the 4th hour to about 3%.

关键词： Photovoltaic systems Predictive models Data models Mathematical model Forecasting

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Parameter calculation for induction machine rotor bar with non-sinusoidal current

Parameter calculation for induction machine rotor bar with n...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Xinzhen Wu Xiangheng Wang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)7506274078

To evaluate the rotor bar parameters of an induction machine with the non-sinusoidal current, a new analysis approach, which employs the circuit analysis theory instead of electromagnetic field theory to count the skin effect, is proposed. In the presented method, a rotor bar is divided into many thin-layers with their own parameters derived. The superposition principle is proven for the calculation of total bar losses and slot magnetic energy due to the non-sinusoidal current composed of sinusoidal components with different frequencies, which shows the parameters of the bar can be expressed with the parameters at respective frequencies. For given examples, the parameters at different frequencies are calculated, and the results are verified by the analytical method or the finite element method.

关键词： Induction machines Skin effect Frequency Rotors Electromagnetic analysis Circuit analysis Magnetic losses Magnetic analysis Finite element methods power system simulation

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Calculation of surface electric field on UHV transmission lines under lightning stroke

Calculation of surface electric field on UHV transmission li...

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作者： Yu, Zhanqing Li, Qian Zeng, Rong He, Jinliang Zhang, Yong Li, Zhizhao Zhuang, Chijie Liao, Yongli State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Department of Mathematical Sciences Tsinghua University Beijing 100084 China Electric Power Research Institute China Southern Power Grid Guangzhou China

Lightning is the major cause of interruptions in power transmission lines. Ultra-high voltage (UHV) AC transmission line has been put into operation in China. Due to the large tower height up to 90 m and the high operation voltage up to 1000 kV, the shielding failure probability increase obviously. Nowadays the leader progression model is an advanced method to evaluate the shielding failure probability of transmission lines. The surface electric field is the key issue for lightning failure analyzing, because the upward leader inception mainly depends on the surface electric field. In this paper, the lightning leader model is introduced. A charge simulation method based piecewise linear function is adopted to analyze the surface electric field on phase conductors and ground wires. The influence factors, such as operation voltage, lightning peak current, lightning down leader position, protection angle, on surface electric field were analyzed. © 2012 Elsevier B.V. All rights reserved.

关键词： Electric lines

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Soft-switching analysis of a resonant capacitor current feedback self-oscillating inverter

Soft-switching analysis of a resonant capacitor current feed...

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2012 IEEE 7th International power Electronics and Motion control Conference - ECCE Asia, IPEMC 2012

作者： Shao, Mingsong Huang, Songling Zhao, Wei Wang, Changquan State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Lighting Research Center Century Zhuoke Energy and Technology Co. LTD Beijing China

ISBN: (纸本)9781457720864

In this paper, we examine a resonant capacitor current feedback (RCCF) self-oscillating resonant inverter from nonlinear point of view. By adopting a four-stage equivalent model, we derive the soft-switching dead time from time-domain for the series resonant capacitor linked parallel load circuit. Importantly, we propose a nonlinear model for the current feedback and gate-drive circuit. Based on analyzing the switching transition interval of this model, the determination of feedback parameters is inferred with given input power and resonant elements. Experimental results have been obtained for a RCCF self-oscillating inverter operating at 3 MHz and 300 V bus voltage. © 2012 IEEE.

关键词： Feedback

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Substation-control center two-level distributed network modeling

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第9期38卷 107-113and151页

作者： Wang, Jing Sun, Hongbin Chen, Runze Zhang, Yang Wu, Wenchuan Guo, Qinglai 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 National Electric Power Dispatching and Control Center Beijing100031 China

As the traditional centralized network modeling for energy management system (EMS) in control center is error prone, heavily reliant on maintenance, and lacking in self-healing ability while unable to satisfy the needs of the distributed application of future transmission grid, a method of substation-control center two-level distributed network modeling is presented. The information model including the network model as well as one-line diagram is built in the substation, transferred to the control center after transformation, and then merged to form an entire network model in control center. The architecture and key technologies such as substation modeling, model transferring and transforming, model joining are discussed in detail. The proposed method has been successfully implemented in China Eastern Grid as shown in the field-application results. ©2014 state Grid Electric power Research Institute Press.

关键词： Energy management systems

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Open-Source Chinese power System with High Spatial and Temporal Resolution 5

Open-Source Chinese Power System with High Spatial and Tempo...

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5th International Conference on Energy, Electrical and power Engineering, CEEPE 2022

作者： Li, Bo Chen, Minyou Zhong, Haiwang Kammen, Daniel M. Li, Xuyang Chongqing University School of Electrical Engineering Chongqing China Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipment Beijing China Unversity of California Berkeley Energy and Resource Group Berkeley United States

ISBN: (纸本)9781665479059

generation Expansion Planning (GEP), electricity market, and grid operation of the power system require a high spatial and temporal resolution model. However, limited data availability is the main obstacle to building a power system model with high resolution. This paper presents a method of constructing an open-source test power system with a high spatial resolution for transmission line topology and generation infrastructures and temporal resolution for variable renewable energy (VRE) sources and electricity demand. In addition, investment and operating cost information of existing infrastructures are summarized. A high-resolution open-source test power system representing China is created only by using publicly available data. The open-source Chinese power system can be used for the GEP model to investigate the low-carbon transition of the power system. © 2022 IEEE.

关键词： Renewable energy sources power engineering power transmission lines Energy resolution power systems Topology Planning

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A power Conversion System For Large-Scale Reversible SOFC Energy Storage System

A Power Conversion System For Large-Scale Reversible SOFC En...

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IEEE Electronic power Grid (eGrid)

作者： Hongsheng Chong Kai Sun Huan Chen State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781665449809

As the penetration rate of renewable energy in the utility grid increases, large-scale energy storage system (ESS) will become an essential infrastructure in the grid. Reversible solid oxide fuel cell (RSOFC) technology is a promising solution for large-scale ESS. However, the wide voltage range and low power of single RSOFC stack electrical characteristics have complicated the interface converter design. It is necessary to connect multiple stacks through a power conversion system to integrate the power because a single stack of RSOFC is small. This paper proposes a power conversion system for large-scale RSOFC ESS. The system consists of a cascaded H-bridge (CHB) converter and multiple multiport converters, and they are connected to a common dc bus. Because of the electrical characteristics of RSOFC, a two-stage CLLC based multiport converter topology is employed to achieve high voltage gain and operate at a wide voltage range. The control strategy of the proposed power conversion system is presented. simulation tests verify the feasibility and effectiveness of the proposed conversion system

关键词： Renewable energy sources Conferences Fuel cells High-voltage techniques Electric variables Solids Topology

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