• 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.

Operating Characteristic Analysis of the Induction Generator by the Reactor Starting (리액터 기동 유도발전기의 동작 특성 해석)

  • Kim, Jong-Gyeum
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.3
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    • pp.138-142
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    • 2014
  • In general, the voltage stability of induction generator is lower than synchronous generator. However, induction generator has many advantages rather than a synchronous generator in terms of price and maintenance. So Induction generator is used little by little in small hydroelectric power station rather than 1000kW recently. Squirrel cage induction generator generates a high inrush current at the grid-connection. This high inrush current causes a voltage drop on the grid. In order to increase the penetration of the induction generator, it is necessary to present a method of reducing inrush current. In this study, we suggested that it is possible to present a reactor startup method, by applying the parameter to reduce the voltage drop.

A Development of Surface Permanent Mount Synchronous Generator for 5 Phase 5KW (5상 5KW 표면부착형 영구자석 동기발전기(SPMSG) 개발)

  • Jung, Hyung-Woo;Kim, Min-Huei;Kim, Dong-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.11
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    • pp.87-96
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    • 2012
  • This paper propose a development of surface permanent mount synchronous generator(SPMSG) for 5-phase 5Kw in order to study a polyphase ac machinery that keep hold of advantages more than traditional three-phase squirrel-cage induction motor, such as reducing a amplitude of torque pulsation decreasing electric noises, and increasing the reliability. Design methods of the generator use a development tools with Maxwell 2D and Simplorer. There are designed drawing of manufactured frames of the SPMSG. A amplitude and waveform of the generated electromotive force, FFT analysis of harmonics within output voltages, and reviewing a experiment results are shown by variable output frequency. We are presenting a design and manufacture methods for the SPMSG.

A Study on the Dual PWM Digital Excitation System of Regeneration Type (회생형 이중화 PWM 방식의 디지털 여자시스템에 관한 연구)

  • Ryu, Ho-Seon;Lee, Joo-Hyun;Lim, Ick-Hun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.9
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    • pp.79-84
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    • 2010
  • This paper discusses the control of generator field using dual IGBT PWM regeneration method to target brushless synchronous generator. If one of PWM bridges happens to fault, it transfers automatically and can be in charge of full load. Also it has an advantage of the operation which UPS connected in parallel with PWM bridge can supply power to excitation system in condition of main power loss. This PWM system supplies field current to generator in one quadrature operation, regenerates field coil energy to main power supplier in four quadrature operation. We designed, manufactured and applied the first trial product at J-power plant.

Simulation and Experiment of Dynamic Torsional Vibration during Grid Low Voltage in a PMSG Wind Power Generation System (PMSG 풍력발전시스템에서 전원 저전압 발생시 비틀림 진동 동특성 시뮬레이션 및 실험)

  • Kwon, Sun-Hyung;Song, Seung-Ho
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.3
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    • pp.211-216
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    • 2013
  • A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. The simulation based on MATLAB/SIMULINK has validated at the transient state of the PMSG and an experiment using 3kW simulator has validated the LVRT control.

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.

Low-Voltage and High-Current DC Output Realized by Multiple Power Cells Based on Deadbeat and Automatic Current Sharing Control

  • Liu, Jinfeng;Zhang, Yu;Wang, Xudong;IU, Herbert Ho-Ching
    • Journal of Electrical Engineering and Technology
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    • v.12 no.4
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    • pp.1575-1585
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    • 2017
  • This paper presents a synchronous generator with a distributed system of multiple parallel three-phase power cells. This generator can immediately output high DC. Each power cell comprises three-phase windings and a three-phase synchronous rectification bridge with a deadbeat control of load power feedforward, which can improve the characteristics of dynamic response and reflect the load variance in real time. Furthermore, each power cell works well independently and modularly using the method of automatic maximum current sharing. The simulation and experimental results for the distributed controller of multiple power cells demonstrate that the deadbeat control method can respond quickly and optimize the quality of the energy. Meanwhile, automatic maximum current sharing can realize the validity of current sharing among power cells.

Soft Start-up Characteristics Analysis of Squirrel Cage Induction Generator (농형 유도 발전기의 소프트 기동 특성 해석)

  • Kim, Jong-Gyeum;Park, Young-Jeen
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.1
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    • pp.103-107
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    • 2016
  • In general, the voltage stability of induction generator is lower than synchronous generator. Induction generator has a number of advantages over the synchronous generator on the side of price and maintenance. So Induction generator has been applied to the small hydroelectric power of low output. Induction generator usually generates a high current during grid connection. The high current that occurs during grid connection can cause a voltage drop in the system. In order to increase the supply of the induction generator, it is necessary to propose a method of reducing high current. This paper proposes some method of the soft start to reduce voltage drop caused by the large starting current. soft-start method has high voltage drop effect than direct start method, control of firing angle can be increased the voltage drop effect.

Characteristics Analysis for Motor or Generator Operating of Induction Machine with Deep or Double Cage Rotor (심구 또는 이중 농형 회전자를 가진 유도기의 전동 또는 발전 운전시 특성 해석)

  • Kim, Jong-Gyeum
    • New & Renewable Energy
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    • v.10 no.4
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    • pp.3-8
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    • 2014
  • Both of induction generator and synchronous generator is available in the hydroelectric power plant. If the output of the power station is large, the synchronous generator is mainly used but when its output is low, the induction generator is often used. If the output capacity is small, there is a case in which induction motor is used as a generator. Torque at rated operation and start of the induction motor is different depending on the shape of the rotor. Small and medium-sized squirrel-cage induction motor is used primarily double cage rotor or deep bar. In this study, we attempt to interpret characteristics for double cage rotor or deep bar that occur when operating in the induction generator based on the parameters that have been designed and manufactured as an induction motor.

The Performance Improvement of Excitation System using Robust Control with DATABASE

  • Hong, Hyun-Mun;Jeon, Byeong-Seok;Kim, Jong-Gun;Lee, Sang-Hyuk
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.5 no.1
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    • pp.83-87
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    • 2005
  • This paper deals with the design and evaluation of the robust controller for a synchronous generator excitation system to improve the steady state and transient stability. The nonlinear characteristics of the system is treated as model uncertainties, and then the robust control techniques are introduced into the power system stability design to take into account these uncertainties at the controller design stage. The performance of the designed controller is examined by extensive non-linear time domain simulation. It is shown that the performance of the robust controller is superior to that of the conventional PI controller. This paper also proposes an improved digital exciter control system for a synchronized generator using a digitally designed controller with database. Results show that the proposed control system manifests excellent control performance compared to existing control systems. It has also been confirmed that it is easy for the proposed control system to implement digital control.