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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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A computer control and monitoring system for high power converters

A computer control and monitoring system for high power conv...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Rong Yi Zhenming Zhao Xiaoying Sun Liqiang Yuan Jue Qian Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)7506274078

Computer control and monitoring system (CCMS) is quite important for high power converters (HPCs) operation. This paper presents a novel CCMS, which integrates a database management system (DBMS) into the monitoring software to get the beneficial features such as simple configuration and compact structure. In its communication system, an advanced optical fiber communication (OFC) technology is applied and priority-based communications is proposed to improve the reliability and the real time of the communications. Furthermore, a friendly standard Windows human-machine interface (HMI) is provided. The reliability and performance of the system are verified by system tests and practical operations.

关键词： control systems Computerized monitoring Communication system control Electromagnetic interference Diodes power engineering computing power system simulation Optical fiber communication Real time systems Man machine systems

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PEEC method for modeling current distribution in grounding plane

PEEC method for modeling current distribution in grounding p...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Han Beibei Sun Xudong Jiang Jianguo State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

In view of the impossibility of current measurement in actual grounding plane in power electronic equipment, an equivalent circuit model is set up in this paper using the partial element equivalent circuit (PEEC) method to simulate and calculate current distribution in grounding plane. The inductance parameters calculated are fairly coincident with experiment results, and some conclusions of current distribution are summarized. It is shown that the equivalent circuit model using PEEC method presented in this paper is a feasible and promising way to model and calculate current distribution in grounding plane

关键词： Current distribution Grounding Equivalent circuits Electromagnetic compatibility Conductors power electronics power system modeling Circuit simulation Impedance Current measurement

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Design and Experiments of Two Glued Axially-Laminated Synchronous Reluctance Permanent Magnetic Motors

Design and Experiments of Two Glued Axially-Laminated Synchr...

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International Conference on power Electronics and Drive systems (PEDS)

作者： Wei Guo Zhengming Zhao Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Two axially-laminated glued axially-laminated synchronous reluctance permanent magnetic (SR-PM) motors are designed and tested. Compared to general axially-laminated synchronous reluctance (SR) motors, the steel bracket is replaced with iron lamination for reduction of iron loss in rotor. The axially-laminated iron and magnet are glued on the bracket with high strength cement with the help of special clamping device. Then the rotor is grinded to the cylinder and a stainless steel rotor sleeve is added to enhance the strength. The design flow starts with initial sizes trade-off and static performance analysis followed by high speed performance validation and dynamic operation simulations. The electromagnetic parameters measurement, no-load and load test are carried out on test bed to verify the design. The comparison of these two sample motors are given for future design reference. It can be concluded that very poor max energy product PM material is not a good choice for application that requires high power density

关键词： Permanent magnet motors Reluctance motors Synchronous motors Testing Iron Rotors Steel Strontium Lamination Magnetic devices

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simulation, Test and Analysis of Three-phase Short-Circuit Braking in IGCT-based MV Adjustable Speed Drive systems

Simulation, Test and Analysis of Three-phase Short-Circuit B...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Zhang Haitao Zhao Zhengming Yuan Liqiang Bai Hua State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

In the medium voltage adjustable speed drive (MV-ASD) systems, low switching frequency results in high harmonics in the output voltage waveform, which is harmful to the isolation of the induction motor. Therefore, the power filter is usually set between inverter and motor. However, self-excitation oscillation easily occurs under this structure due to the filter capacitor, which could continuously bring up the DC-link voltage of the inverter, and even destroy the devices in inverters. One of the effective ways to eliminate the self-excitation oscillation is to set the inverter to three-phase short-circuit braking state, which is described and analyzed in detail in this paper. Three-phase short-circuit braking could be easily realized in the inverter-motor system. It can be verified by both simulation based on PSIM and test results that this is an efficient way in real applications. Finally, the characteristics of the short-circuit braking is summarized and beneficial suggestions on using this braking method are presented

关键词： Analytical models System testing Variable speed drives Inverters power harmonic filters Medium voltage Switching frequency Induction motors power filters Capacitors

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Optimum parameters and maximum torque performances of the synchronous reluctance machine

Optimum parameters and maximum torque performances of the sy...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Wang Shijing Zhao Zhengming Guo Wei State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

The permanent magnet assisted synchronous reluctance (SR-PM) machine can not only offer higher torque capacity and improved power factors compared with the conventional synchronous reluctance machine, but also own wider adjustable speed range compared with the permanent magnet machine. This paper presents a new method to optimize the key parameters of the machine under keeping the torque of the machine as large as possible by controlling the stator current. Nonlinear optimization and functional analysis are used to obtain the maximal torque at a certain speed. The investigation of many groups of the parameter data shows that the performance of a machine is influenced by various factors such as magnetic materials, the quantities of the material in the rotor, the turns of windings in the stator and so on. The best one should be chosen for applications. The trend of all the curves verifies the simulation results.

关键词： Reluctance machines Magnetic materials Permanent magnets Reactive power Permanent magnet machines Optimization methods Torque control Functional analysis Stator windings Machine windings

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Accurate flux observer based on distributed multi-processor in MV adjustable speed drive system

Accurate flux observer based on distributed multi-processor ...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Liu Shu Liu Jianzheng Zhao Zhengming Yuan Liqiang Bai Hua Zhang Haitao Department of Electrical Engineering and Applied Electronic Technology State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

This paper presents an accurate flux observer used in distributed multi-processor (DMP) adjustable speed drive systems. The stator flux linkage is estimated with a full-order observer, while the rotor speed is identified by using Lyapunov theorem. In order to improve the system performance in a wide speed range, the stator resistance is estimated simultaneously. In this paper, the structure of the DMP system, the principle of the full-order observer and the method for identifying the rotor speed and state resistance are all described in details. Relevant simulation results based on MATlab/SIMULINK are given to prove the performance of the method. Experiments of a real system also verify the feasibility of this scheme

关键词： Variable speed drives Stators Observers control systems Mathematical model Couplings Torque control Optimal control Sampling methods Pulse width modulation

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A novel fiber-CAN-based real time communication system for MV-ASD systems

A novel fiber-CAN-based real time communication system for M...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Jue Qian Zhengming Zhao Haitao Zhang Hua Bai Liqiang Yuan Department of Electrical Engineering and Applied Electronic Technology State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

The voltage increment in MV-ASD systems deteriorates the electromagnetic environment, therefore the communication system is facing a formidable challenge in the attempt to achieve the numerous real-time interactivities among those subsystems under such electromagnetic circumstance. This paper focuses on the real-time communication system for the MV-ASD systems, in which electromagnetic compatibility (EMC), real-time performance and system reliability are considered simultaneously. A novel fiber-CAN network is designed and implemented, which remarkably increases EMC compared to the conventional ones. The CAN system that serves in the multiprocessor control system for the MV-ASD system with the rated power of 1 MW is implemented. From the experiment results in the MV-ASD system with a 690 kW motor, it can be verified that the requests of timing performance and the reliability for the communication system are well accomplished

关键词： Optical fiber communication Real time systems control systems Communication system control Circuits Torque control Electromagnetic compatibility Pulse width modulation inverters Optical fiber devices power system simulation

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Research on switching overvoltage in 1000 kV ultra-HVAC transmission line

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2005年第SUPPL.期25卷 214-219页

作者： Xu, Wei Chen, Shui-Ming He, Jin-Liang Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

Combined with a single circuit UHV power transmission project in one million voltage from Jincheng to Jingzhou via Nanyang which is reasoned by State power Grid Corp. of China, its switching overvoltages, including three-phases closing with no load and single-phase auto-reclosing, are considered. The switching overvoltages are calculated with Electromagnetic Transient Program (EMTDC). The calculation shows that the switching overvoltage is too high up to 1.80 pu if only with parallel resistor in circuit breaker or high performance ZnO arrester. Combining arrester and parallel resistor is a good measure to limit switching overvoltage without such high requirement on arrester's or resister's thermal capacity.

关键词： UHV power transmission

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Extended load-flow arithmetic for voltage stability analysis

Extended load-flow arithmetic for voltage stability analysis

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International Conference on power System Technology (powerCON)

作者： L. Zhu S. Zhou Y. Zhang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)0780363388

In this paper, a novel load-flow arithmetic for voltage stability analysis is studied where models of various dynamic elements in power systems are taken into account. It simultaneously solves the load flow equation and the state equation of dynamic elements and gets both the voltage amplitude, phase of all buses and the inner state variables of the dynamic elements. In this arithmetic different limits are considered and the assumption of PV bus, PQ bus and slack bus are eliminated, so the result is closer to the real operation condition. Using a flow arithmetic based on continuation-power-flow (CPF) method, the critical point of voltage stability of the system can be computed. The proposed method is demonstrated on a test system and the results are compared with the conventional power flow method.

关键词： Arithmetic Voltage Stability analysis power system dynamics power system modeling Load flow Equations power system analysis computing power system stability System testing

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