• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.37-41
• /
• 2007

Fast Fourier Transformation(FFT) is one of the most useful way to analyze response signal for the purpose of grasping the dynamic characteristics of system. Excitation is a factor or process making noise or vibration. It's typical and simple experimental method widely used for catching hold of dynamic peculiar characters and modal behaviors of system by frequency analysis. There are harmonic excitation, impact excitation, random excitation, sweep excitation, chirp excitation and so on as the ideal method in an experiment using exciter. In this thesis, excitation testing module for NI-PXI equipment is developed. The analyzing module is developed with LabVIEW tool. A user can generate each waveform for shaking a structure and see quickly and easily modal shape of system with this module. This developed module will be expected to build up more convenient and serviceable measurement system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
• /
• pp.125-128
• /
• 2000

This paper presents an energy function which provides the direct relationships between the system stability and parameters of the exciter system. The energy function is derived from the energy conservation law by using the first motion integral. he time derivative does not absolutely satisfy the seminegativeness. However dE/dt usually has big negative value just after the fault clearing so that the energy is rapidly decreased. In this situation, the system state can be obviously confined in a stable region if the intial energy is less than the UEP energy. With these observation, two theorems are developed regarding the state confinement and asymptotic stability. Based on two theorems a new approximated direct energy method is developed to analyze the transient stability with the consideration of the exciter control effects. The proposed method has been tested for a single-machine-infinite bus system.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.59-64
• /
• 2003

The parameter modification of the initial FEM model to match it with the experimental results needs the modal information and the modal sensitivity matrix to the parameter change. There are two cases this methodology is ill-equip to deal with; the deficiency of the necessary modal information and the ill-conditioning of the sensitivity matrix. In this research, a novel concept of the feedback exciter that uses the summation of the white noise and the signals from the measurement sensors multiplied with feedback gains as the reference signal is proposed. There are 2 advantages using this external feedback excitation. First, we can use the change of the system response such as modal data by the active energy Path from the sensor to the exciter. This change of the system response can be additional clues to the system dynamics that we want to know. Secondly, the external energy Path alternates the offset of the Parameter change to the system response. That means the modal sensitivity of the parameters becomes different from the original sensitivities by the feedback excitation. Through the feedback loop, we can change the similar modal sensitivities of some updating parameters and consequently discriminate the parameters using the closed-loop modal data. To demonstrate the discrimination performance, the parameter estimation of an indeterminate structure by use of the feedback method is introduced.

• 전기학회논문지
• /
• 제67권4호
• /
• pp.561-568
• /
• 2018

Passivity theory is significantly applied to analyze stability of nonlinear dynamic systems and construct its stable control systems. This paper presents a passivity based control design approach for exciters and governors which are employed to regulate the terminal voltage and the rotor velocity of synchronous generator systems in industry fields. We consider the IEEE type 1 exciter and the gas turbine (GT) governor models respectively in this paper. We first carry out a passivity analysis for exciter and governor control systems, which are numerically obtained from its mathematical models. And then its control parameters are selected to assure passivity conditions in a design procedure. Lastly, we investigate numerical simulations to demonstrate reliability of the proposed control approach against large-scale generators with parameter changes.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제52권8호
• /
• pp.420-426
• /
• 2003

This paper deals with the effect of exciter parameters on the torsional stress of turbine-generator. The excitation system effects on the AC network stability and the turbine-generator stress. However. it, until now, have not reported that any parameter among exciter parameters is related to the stability and the stress. In order to verify those CIGRE HVDC model was used. Since the AC network with HVDC has the voltage stability problem due to big capacitor, the worst condition to analyze the stress can considered. The EMTDC program is used for the simulation studies.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.381-387
• /
• 2002

In this work, the dynamic characteristics of an oil-lubricated, short SFD with a central feeding groove are derived based on a theoretical analysis considering the effect of a groove. The validity of the analysis is investigated experimentally using an Active Magnetic Bearing (AMB) system as an exciter. For the theoretical solution, the fluid film forces of a grooved SFD are analytically derived so that the dynamic coefficients of a SFD are expressed in terms of its design parameters. For the experimental validation of the analysis, a test rig using AMB as an exciter is proposed to identify the dynamic characteristics of a short SFD with a central groove. As an exciter, the AMB represents a mechatronic device to levitate and position the test journal without any mechanical contact, to generate relative motions of the journal inside the tested SFD and to measure the generated displacements during experiments with fairly high accuracy. Using this test rig, experiments are extensively conducted with different clearance, which is one of the most important design parameters, in order to investigate its effect on the dynamic characteristics and the performance of SFDs. Damping and inertia coefficients of the SFD that are experimentally identified are compared with the analytical results to demonstrate the effectiveness of the analysis. It is also shown that AMB is an ideal device for tests of SFDs.

• 전기학회논문지P
• /
• 제63권2호
• /
• pp.74-80
• /
• 2014

Generator protection device has to detects an internal fault conditions in generator and abnormal operating conditions must be due to the hazards. Loss of excitation may cause generator itself failure as well as serious operating problem in power system, and then requires an appropriate response of generator protection device. Details modeling of generator control system and analysis of transient states in generator are important for optimal operation in power plants. In addition, the fault simulation data are also used for testing the characteristics of IED. In this paper, the hydro generator control system using PSCAD/EMTDC, visual simulation for power systems, was modeled. The generator control system which is composed of generator, turbine, exciter, governor was implemented. The parameters of generator control system model were obtained from field power plant. Loss of excitation simulations were performed while varying the fixed load. Several signals analysis were also performed so as to analyze transients phenomena.

• 조명전기설비학회논문지
• /
• 제24권12호
• /
• pp.193-200
• /
• 2010

In this paper, the eigenvalue sensitivity analysis is calculated in the power system which is including both generator controllers such as Exciter, PSS and thyristor controlled FACTS devices in transmission lines such as TCSC. Exciter and PSS are continuously operating controllers but TCSC has a switching device which operates non-continuously. To analyze both continuous and non-continuous operating equipments, the RCF method one of the numerical analysis method in discrete time domain is applied using discrete models of the power system. Also the eigenvalue sensitivity calculation algorithm using state transition equations in discrete time domain is devised and applied to a sampled system. As a result of simulation, the eigenvalue sensitivity coefficients calculated using discrete system models in discrete time domain are changed periodically and showed different values compared to those of continuous system model in time domain by the effect of periodic switching operations of TCSC.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2007년도 추계학술대회 논문집
• /
• pp.225-229
• /
• 2007

The output voltage of a synchronous generator is regulated constantly by field current control of excitation system. Synchronous generator exciter has two type, first one is Drop control type by thyristor and second one is exciter current control type through power output by PWM control. Control method of the second one prevails, but when the power devices have a breakdown, output voltage of the generator rises rapidly. This exciter must have a protection circuit and system is complicated, so reliability is poor Excitation control type which is drop control type control only 10% of the power, so it can be improved precision. When a trouble come to the controller, output voltage of a generator don't rise excessively and the voltage rise about 10%, so it has a excellent reliability. This paper prove stability of the digital AVR.

• 전기학회논문지P
• /
• 제65권2호
• /
• pp.101-107
• /
• 2016

The main target in this paper is the localization of VME Type EPSM in Generator Exciter(EX2100) System. Developed EPSM has the compatibility with the existing product in the structure and shape and electrical feature and so on, but it has a much improved capacity and reliability in comparison with origin company product. this paper, to improve these functions, put emphasis on protection, monitoring, power capacity increase(over 120%), an enlarged scale of input voltage supply, AC/DC dual voltage use and so on. After manufacturing product localization, it was carried out several tests for the performance and reliability verification of developed product. These tests were performed in Authorized Inspection Agency(KTL) and field application test and maker self-test were additionally performed. Finally, the results of all tests were "success".