• Title, Summary, Keyword: synchronous generator

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Semi-analytical Method for Predicting Shaft Voltage in Field-excited Synchronous Generators

  • Doorsamy, Wesley;Cronje, Willem A.
    • Journal of Power Electronics
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    • v.14 no.5
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    • pp.859-865
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    • 2014
  • This study presents an electromagnetic model for predicting shaft voltages in a 2-pole field-excited synchronous generator. After the first observations on shaft voltages were made more than a century ago, extensive work has been conducted on eliminating, mitigating, and integrating the aforementioned phenomena. Given that emphasis has been placed on modeling shaft- and bearing-induced voltages in AC motors driven by variable frequency drives, similar efforts toward a model that is dedicated to generators are insubstantial. This work endeavors to improve current physical interpretation and prediction methods for shaft-induced voltages in generators through semi-analytical derivation. Aside from the experimental validation of the model, investigations regarding the behavior of shaft voltages under varying machine complexities and operating conditions clarify previous uncertainties regarding these phenomena. The performance of the numerical method is also assessed for application in eccentricity fault diagnosis.

Initial Magnetic-Circuit Design of High Speed Permanent-Magnet Synchronous Machine (초고속 영구자석 동기기의 기초자기회로설계)

  • Joo, Daesuk;Hong, Do-Kwan;Woo, Byung-Chul;Woo, Kyung-Il;Park, Han-Seok
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.64 no.1
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    • pp.7-13
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    • 2015
  • This paper presents mathematical models for high speed permanent-magnet synchronous machine. The mathematical method with two successive steps is used to estimate design parameter as well as the output power. At first, mathematical model for a linkage flux problem is employed to calculate the number of winding turns and stack length of armature core. The magnetic circuit model for an induced voltage and the electric circuit model for a current are modeled. The output powers of the electrical generator were evaluated by the mathematical techniques. The results of this mathematical methods predict the specifications of the machine and can be applied in the design stage of the electrical machine.

SDRE Based Near Optimal Controller Design of Permanent Magnet Synchronous Generator for Variable-Speed Wind Turbine System (가변속 풍력 발전용 영구자석형 동기발전기의 SDRE 기반 준최적 비선형 제어기 설계)

  • Park, Hyung-Moo;Choi, Han Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.1
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    • pp.28-33
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    • 2015
  • In this paper, we propose a near optimal controller design method for permanent magnet synchronous generators (PMSGs) of MW-class direct-driven wind turbine systems based on SDRE (State Dependent Riccati Equation) approach. Using the solution matrix of an SDRE, we parameterize the optimal controller gain. We present a simple algorithm to compute the near optimal controller gain. The proposed optimal controller can enable PMSGs to precisely track the reference speed determined by the MPPT algorithm. Finally, numerical simulation results are given to verify the effectiveness of the proposed optimal controller.

A Comparative Study on Power Generation Characteristics of Permanent Magnet Synchronous Generators for Green Ship

  • Kato, Shinji;Cho, Gyeong-Rae;Michihira, Masakazu
    • Journal of the Korean Society of Marine Engineering
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    • v.36 no.3
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    • pp.378-386
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    • 2012
  • For reduction of the amount of CO2 emitted from ships, power generation characteristics of two power generation systems consisting of a high-efficiency permanent magnet synchronous generator and diode bridge rictifiers are discussed in this paper. One of the discussed systems has three-phase stator windings, and the other has two sets of three-phase (six-phase) stator windings to reduce pulsation in the electromagnetic torque and DC current. Experimental results reveal that the power generation efficiency of the system having six-phase stator windings is higher than that of the system having three-phase stator windings for a light load. The maximum power generation efficiency of the system having six-phase stator windings is almost the same as that of the system having three-phase stator windings. For the electromagnetic torque of the system having six-phase stator windings, the width of pulsation is about one-fifth compared to the system having three-phase stator windings.

Transient Characteristic Analysis of Damper in Superconducting Synchronous Generator by the Compensated 2D Analysis Model (보정된 2차원 해석모델에 의한 초전도 동기발전기의 댐퍼 과도특성 해석)

  • Chun, Yon-Do;Lee, Hyung-Woo;Lee, Ju;Hong, Jung-Pyo;Kwon, Young-Kil;Ryu, Kang-Sik
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.2
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    • pp.93-101
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    • 2000
  • This paper presents a novel method for the transient of eddy currents in the dampers of a super-conducting synchronous generator(SCG). The method proposes a 2-D corrected model which takes into account the influence of leakage fluxes of the field winding ends by increasing the effective air gap in order to consider the high precision of the analysis for the conventional 2-D model. The electromagnetic fields for the corrected model are analyzed by the time-stepping finite element method, thus the eddy currents in the dampers and electro-motive forces(EMF) in the stator windings are calculated. As the results, it is proved the presented method is comparatively accurate by comparing measured phase EMF values and the simulation ones, where about 6.4% error at the maximum value of EMF is occurred between them.

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An Approach to the Design Parameter of Air-Cored Superconducting Synchronous Generator (공심형 초전도 동기발전기의 설계변수에 대한 연구)

  • Jo, Young-Sik;Hong, Jung-Pyo;Lee, Ju;Sohn, Myung-Hwan;Kwon, Young-Kil;Ryu, Kang-Sik
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.3
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    • pp.101-106
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    • 2001
  • Air-cored superconducting synchronous generator(ASSG) is characterized by an air-cored machine with its rotor iron and stator iron teeth removed. For this reason, in the case of the shape optimum design of ASSG, other design variables different from an iron-cored machine should be considered, which will lead to substantial improvement on the performance. The major design variables that are considered by using Three-dimensional Finite element Method(3D FEM) in this paper are : 1) field coil width, 2) axial length of magnetic shield, and 3) armature winding method. End-ring of armature winding is considered in the calculation of EMF. When it comes to field coil width, as field coil width enlarges, its effective field increases but the maximum field on the superconductor decreases. this determines the critical current density. this study presents an effective field coil width, axial length of magnetic shield, and armature winding method, and also the analysis is verified by the experimental results.

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Dynamic Allocation Algorithm for enhancement of transmission performance on a radio encryption system (무선암호시스템에서 전송성능 개선을 위한 동적할당 알고리듬)

  • 홍진근;윤장홍;장병화;황찬식
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.11 no.1
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    • pp.3-12
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    • 2001
  • In this paper, a synchronized stream encryption system for secure link layer communication in a radio channel is designed. Interleaving scheme which is used to enhance the transmission performance over a fading channel is applied to the encrypted information. A designed synchronous scream cipher system consists of a keystream generator, a synchronization pattern generator and a session key generator. The structure of a synchronous stream cipher system with periodic synchronization is composed of the encrypted information which consists of a synchronization pattern, an error correcting coded session key, an encrypted data in a period of synchronization. In this paper, interleaving scheme using dynamic allocation a1gorithm(DAA) is applied the encrypted information. The BER of the DAA has been slightly higher than that of the SAA(static allocation algorithm).

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Study of Shorted-turn for Cylindrical Synchronous Generator Rotor (원통형 동기발전기 회전자의 층간단락에 관한 연구)

  • Kim, Young-Jun;Kim, Jang-Mok;Lee, Sang-Hyuk;Ahn, Jin-Woo
    • Journal of the Korean Society of Safety
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    • v.21 no.2
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    • pp.52-56
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    • 2006
  • This paper describes the methods for the detection of shorted-turn in the rotor of a cylindrical synchronous generator. A search coil is installed in the air-gap to detect the shorted-turn. The occurrence of a fault in the rotor winding results in a decrease of the induced voltages in the stator. And the magnitude of the rotor flux can be estimated by using the search coil and the estimated stator voltages respectively. And the magnitude of the estimated rotor flux is used for discriminating the rotor windings short or not by detecting the magnitude of the rotor flux. The method using a search coil located in the air-gap can detect not only the occurrence of a turn fault but also its position in the rotor winding. But the method using the estimated stator voltages gives the magnitude of the rotor flux, and only the number of a short-turn.

Analysis and Optimization of the Axial Flux Permanent Magnet Synchronous Generator using an Analytical Method

  • Ikram, Junaid;Khan, Nasrullah;Junaid, Qudsia;Khaliq, Salman;Kwon, Byung-il
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.257-265
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    • 2017
  • This paper presents a 2-D analytical method to calculate the back EMF of the axial flux permanent magnet synchronous generator (AFPMSG) with coreless stator and dual rotor having magnets mounted on both sides of rotor yoke. Furthermore, in order to reduce the no load voltage total harmonics distortion (VTHD), the initial model of the coreless AFPMSG is optimized by using a developed analytical method. Optimization using the 2-D analytical method reduces the optimization time to less than a minute. The back EMF obtained by using the 2-D analytical method is verified by a time stepped 3-D finite element analysis (FEA) for both the initial and optimized model. Finally, the VTHD, output torque and torque ripples of both the initial and optimized models are compared with 3D-FEA. The result shows that the optimized model reduces the VTHD and torque ripples as compared to the initial model. Furthermore, the result also shows that output torque increases as the result of the optimization.

Flicker Mitigation in a Wind Farm by Controlling a Permanent Magnet Synchronous Generator (영구자석형 동기발전기를 이용한 풍력단지의 플리커 저감)

  • Hoan, Pham Van;Kim, Dae-Hyun;Ahn, Jin-Hong;Kim, Eel-Hwan;Oh, Seong-Bo;Kim, Ho-Chan;Kim, Se-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.12
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    • pp.1163-1168
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    • 2009
  • The power quality of wind energy becomes more and more important in connecting wind-farms to the grid, especially weak grid. This paper presents the simulation of a wind farm of a permanent magnet synchronous generator (PMSG) and a doubly fed induction generator (DFIG). Flicker mitigation is performed by using PMSG as a static synchronous compensator (STATCOM) to regulate the voltage at the point of common coupling (PCC). A benefit of the measure is that integrating two function of to control the active power flow and to reduce the voltage flicker in a wind farm. Simulation results show that controlling PMSG is an effective and economic measure in reducing the flicker during continuous operation of grid connected wind turbines regardless of short circuit capacity ratio, turbulence intensity and grid impedance angle.