• Title/Summary/Keyword: synchronous generator

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Design of Excitation Control System of Synchronous Generator on Board Ships (선박용 동기 발전기의 여자 제어시스템 설계)

  • Lee, Youngchan;Jung, Byung-Gun
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.3
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    • pp.298-305
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    • 2015
  • This paper provides experimental results of an excitation control system of the synchronous generator on board ships in accordance with rules of classification society to make sure its performance. The experiment compares and reviews control results between PID control and fuzzy logic control applied to change of loads of the generator in order to make sure to satisfy the rules of classification society. Both of them are written by Labview program. In case of PID Control, this paper firstly adjusts the gains by ultimate sensitive method and the gains is more tuned by engineer's experience. And the fuzzy logic controller uses Mamdani method to make membership function for error between reference voltage and measuring voltage, differential error rate and output voltage. This paper is to make sure the experimental results of the proposed excitation control system applied to actual small synchronous generator with PID control and fuzzy logic written by using Labview program and it is proved on stability and improvement through experiments.

Voltage Control of Synchronous Generator for Ships using a PMG Type Digital Automatic Voltage Regulator (PMG Type 디지털 AVR을 이용한 선박용 동기발전기 출력전압제어)

  • Yu, Dong-Hwan;Park, Sang-Hoon;Won, Chung-Yuen;Yu, Jae-Sung;Lee, Sang-Seuk;Ahn, Sung-Joon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.14 no.1
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    • pp.38-45
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    • 2009
  • To get the constant output, synchronous generator field excitation is controlled by AVR(Automatic Voltage Regulator). Most of ships generator AVR uses the thyristor phase controlled rectifier. However this rectifier is difficult to realize that the fast control system because its control period is slower than MOSFET and IGBT type converter. Therefore, this paper deals with PMG(Permanent Magnet Generator) type digital AVR using MOSFET switch for ships synchronous generator. The composition of this digital AVR is very simple, the generator is under the short circuit accident, the output voltage becomes zero state and AVR can not operate. Thus generator is required to add CBC(Current Boosting Circuit) in an excitation circuit to flow output current. The performance of the proposed system is evaluated on a 10[kVA] experimental prototype circuit in place of real ships generator.

Fault diagnosis system of the short circuit conditions in windings for synchronous generator (동기발전기 권선단락사고 고장진단 시스템)

  • Jang, Nakwon;Lee, SungHwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.5
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    • pp.520-526
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    • 2013
  • As the increasing of capacity and technology of power facilities, rotating machines are getting higher at capacity and voltage scale. Thus the monitoring and diagnosis of generators for fault detection has attracted intensive interest. In this paper, we developed fault diagnosis system for monitoring the fault operations in bad power systems. In order to verify the performance of this fault diagnosis system, we made the small scaled testing system which has the same winding structure of the real synchronous generator. The magnetic flux patterns in air-gap of a small-scale generator under various fault states as well as a normal state are tested by hall sensors and the fault detection system.

Analysis of Permanent Magnet Synchronous Generator for Vortex Induced Vibration Hydrokinetic Energy Applications Based on Analytical Magnetic Field Calculations

  • Choi, Jang-Young;Shin, Hyun-Jae;Choi, Jong-Su;Hong, Sup;Yeu, Tae-Kyeong;Kim, Hyung-Woo
    • Journal of Magnetics
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    • v.17 no.1
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    • pp.19-26
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    • 2012
  • This paper deals with the performance analysis and estimation of the electrical parameters of a permanent magnet synchronous generator (PMSG) for hydrokinetic energy conversion applications using vortex induced vibration (VIV). The analytical solutions for the magnetic fields produced by permanent magnets (PMs) and stator winding currents are obtained using a 2D polar coordinate system and a magnetic vector potential. An analytical expression for the 2D permeance is also derived, which takes into account stator skew effects. Based on these magnetic field solutions and the 2D permeance function, electrical circuit parameters such as the backemf constant and the air-gap inductance are obtained analytically. The performances of the PMSG are investigated using the estimated electrical circuit parameters and an equivalent circuit (EC). All analytical results are validated extensively using 2D finite element (FE) analyses. Experimental measurements for parameters such as the back-emf and inductance are also presented to confirm the analyses.

Impact of Fixed Series Capacitors and SSSC on the LOE Protection of Synchronous Generator

  • Ghorbani, Amir;Lima, Hossein Mehryari;Azadru, Allahverdi;Mozafari, Babak
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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    • pp.1453-1459
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    • 2015
  • Loss of excitation (LOE) relay is prevalently used to protect synchronous generator. The widely used method for synchronous generator LOE protection is a negative offset mho relay with two zones. The basis of this relay is identical to mho impedance relay. In other words, this relay calculates impedance by measuring voltage and current at the generator terminal. On the other hand, the presence of series compensation, changes measured voltage and current signals during loss of excitation. This paper reveals that the presence of series compensators such as fixed series capacitors (FSCs) and static synchronous series compensator (SSSC) causes a significant delay on the performance of generator LOE relay. It is also shown that the presence of SSSC causes the LOE relay to be under-reached. Different operating modes of the power system, the SSSC and also different percentages of series capacitive compensations have been considered in the modeling. All the detailed simulations are carried out in the MATLAB/Simulink environment using the SimPowerSystems toolbox.

Damping for Wind Turbine Electrically Excited Synchronous Generators

  • Tianyu, Wang;Guojie, Li;Yu, Zhang;Chen, Fang
    • Journal of Electrical Engineering and Technology
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    • v.11 no.4
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    • pp.801-809
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    • 2016
  • The electrically excited synchronous generator (EESG) is applied in wind turbine systems recently. In an EESG control system, electrical torque is affected by stator flux and rotor current. So the control system is more complicated than that of the permanent-magnet synchronous generator (PMSG). Thus, the higher demanding of the control system is required especially in case of wind turbine mechanical resonance. In this paper, the mechanism of rotor speed resonant phenomenon is introduced from the viewpoint of mechanics firstly, and the characteristics of an effective damping torque are illustrated through system eigenvalues analysis. Considering the variables are tightly coupled, the four-order small signal equation for torque is derived considering stator and rotor control systems with regulators, and the bode plot of the closed loop transfer function is analyzed. According to the four-order mathematical equation, the stator flux, stator current, and electrical torque responses are derived by torque reference step and ramp in MATLAB from a pure mathematical deduction, which is identical with the responses in PSCAD/EMTDC simulation results. At last, the simulation studies are carried out in PSCAD software package to verify the resonant damping control strategy used in the EESG wind turbine system.

Experimental Assessment with Wind Turbine Emulator of Variable-Speed Wind Power Generation System using Boost Chopper Circuit of Permanent Magnet Synchronous Generator

  • Tammaruckwattana, Sirichai;Ohyama, Kazuhiro;Yue, Chenxin
    • Journal of Power Electronics
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    • v.15 no.1
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    • pp.246-255
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    • 2015
  • This paper presents experimental results and its assessment of a variable-speed wind power generation system (VSWPGS) using permanent magnet synchronous generator (PMSG) and boost chopper circuit (BCC). Experimental results are obtained by a test bench with a wind turbine emulator (WTE). WTE reproduces the behaviors of a windmill by using servo motor drives. The mechanical torque references to drive the servo motor are calculated from the windmill wing profile, wind velocity, and windmill rotational speed. VSWPGS using PMSG and BCC has three speed control modes for the level of wind velocity to control the rotational speed of the wind turbine. The control mode for low wind velocity regulates an armature current of generator with BCC. The control mode for middle wind velocity regulates a DC link voltage with a vector-controlled inverter. The control mode for high wind velocity regulates a pitch angle of the wind turbine with a pitch angle control system. The hybrid of three control modes extends the variable-speed range. BCC simplifies the maintenance of VSWPGS while improving reliability. In addition, VSWPGS using PMSG and BCC saves cost compared with VSWPGS using a PWM converter.

Position Sensor Fault Tolerant Control of Permanent Magnet Synchronous Generator (영구자석 동기발전기의 위치센서 고장 회피 제어)

  • Lee, Kwang-Woon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.16 no.4
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    • pp.351-357
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    • 2011
  • Rotor position is essentially required for vector control of permanent magnet synchronous generator(PMSG) and position sensor such as encoder are generally used for the purpose of position sensing. However, the use of position sensor degrades reliability of PMSG control system. This paper presents position sensor fault tolerant control method for PMSG control system. Sensorless position estimator based on extended electromotive force(EMF) is operated in parallel with sensored vector control to provide rapid reconfiguration capability to sensorless vector control at the moment of position sensor fault detection. Experimental results show the effectiveness of the proposed method.

Analysis for Voltage Fluctuation and Power Flow at the Grid-Connected Time of Squirrel-Cage Induction Generator (농형 유도발전기의 계통 연계시 전압 변동 및 전력 흐름 분석)

  • Kim, Jong-Gyeum
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.6
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    • pp.45-51
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    • 2014
  • Synchronous generators and induction generators are mainly used in hydroelectric power generation. Synchronous generator is mainly applied to large hydroelectric plants but induction generator is applied to the small hydro power plants. Stability of induction generator is slightly less than the synchronous generator. However, induction generator has many advantages rather than a synchronous generator in terms of price and maintenance. So Induction generator is used primarily in small hydroelectric power station less than 1,000kW 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 reduce the voltage drop and to analyze the power flow, the analysis for operating characteristics of the induction generator should be reviewed in advance. In this study, we analyzed the voltage drop and power flow analysis when a 1500kW induction generator is connected to the grid. The voltage drop is slightly higher than the acceptable range of distributed power supply voltage and the power flow of the generator is performed well.

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.