• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.658-660
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• 1996

This paper prescribe the effects of SVC & TCSC in multi-machine power system. EMTP models of two FACTS controllers are proposed to analysis the basic characteristics of SVC & TCSC and the control signal of TCR is determined by rms value which was measured in system. The oscillation model of generator is proposed to analysis the damping effect and the most effective location of TCSC in multi-machine power system is identified by the residues associated with the natural oscillation modes. The 3 generator-9 bus model system is used to demonstrate the applicability of the proposed model.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.3
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• pp.122-132
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• 2005

This paper presents a novel approach based on Prony method to analysis of small signal stability in power system. Prony method is a valuable tool in identifying transfer function and estimating the modal parameter of power system oscillation from measured or computed discrete time signal. This paper define the relative residue of time signal and propose the condition to select low frequency oscillation in each generator. This paper describes the application results of proposed algorithm with respect to KEPCO systems. Simulation results show that the proposed algorithm can be used as another tools of power systems analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1703-1707
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• 2008

Low frequency oscillation of inter-area system is important problem in power system areas because the operation conditions of power system depend on it. Generally, the analysis of the problem is used by small signal stability. Especially, the analysis results are affected by decision of load models. In this paper, the effect of the analysis results was studied according to load component characteristics. ZIP model, popular in large-scaled power system analysis, was used as the load model. Many cases were studied according to the combination of ZIP model in inter-area system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.883-888
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• 2014

The paper describes the parameter tuning of power system stabilizer (PSS) for a power plant based on hybrid system modeling. The existing tuning method based on bode plot and root locus is well applied to keep power system stable. However, due to linearization of power system and an assumption that the parameter ratio of the lead-lag compensator in PSS is fixed, the results cannot guarantee the optimal performances to damp out low-frequency oscillation. Therefore, in this paper, hybrid system modeling, which has a DAIS (differential-algebraic-impusive-switched) structure, is applied to conduct nonlinear modeling for power system and find optimal parameter set of the PSS. The performances of the proposed method are carried out by time domain simulation with a single machine connected to infinite bus (SMIB) system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.12
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• pp.63-73
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• 2013

The parameters of electromechanical modes offer considerable insight into the dynamic stability properties of a power system. This paper presents a results of a LFO(low-frequency oscillation) based on the time-synchronized signals measured by synchrophasor in the rolling blackout. Spectral analysis was performed, and critical parameters were estimated using the data acquired from synchrophasors installed in the KEPCO system. As significant modes, a 0.68 Hz oscillation mode that occurred prior to the forced load shedding in the rolling blackout was estimated. Such an oscillation mode can cause an uncontrollable blackout. Therefore, the system should be operated so that significant oscillation modes are not activated. This results can serve as a reference in the future for reliable system operation in the event of a similar blackout.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.5
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• pp.218-224
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• 2001

This paper describes the identification of torsional modes and power oscillation modes including the inter-area modes and local modes of KEPCO using the proposed DFT analysis algorithm which is applied to the digitally recorded RMS values of power system variables such as steady-state measured active power, load angle and so on. As a result, the inter-area mode of 0.65Hz and the local modes of the three different generators were identified. In addition the torsional modes of two steam-turbo generators were analyzed by applying the DFT algorithm. Thus, this paper clearly shows the availability of the proposed DFT algorithm that can analyze the digitally recorded effective values measured from the equipment such as PMU of DSM.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.3
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• pp.140-151
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• 2004

This paper presents the HVDC system modelling for analysis of subsynchronous oscillation and the design of the subsynchronous oscillation damping controller in HVDC system with the aid of novel eigenvalue analysis program. The HVDC system models include both the steady-state model for power flow calculation and the dynamic model for constructing the state matrix. The design procedures of the subsynchronous oscillation damping controller (SODC), which is integrated with PI controller at rectifier, consist of three steps:1) to identify the dominant torsional oscillation mode in the AC/DC system;2) to determine the parameters of the SODC for compensating the phase lagging due to the rectifier controller;3) to validate the control parameters and to determine the appropriate gain using a time-domain simulation program. The proposed design method has been tested against two AC/DC systems for validation.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.259-261
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• 2000

UPFC(Unified Power Flow Controller) consists of two voltage sourced converter(VSC)s inserted into AC system through series and parallel coupling transformer, where two VSCs are linked by capacitor at DC-side. Since VSC acts as an AC voltage source behind a reactance, where both magnitude and phase angle of the source are controllable, UPFC can be represented by the equation related to input-output relation of two VSCs. Voltage control of DC-link capacitor provides the path of real power flow between two VSCs. While UPFC is controlled for maintaining the given reference value in steady state, it should be controlled for damping power oscillation in dynamics. For such a control objective, the control strategy based on the energy function was proposed and has been shown to be effect and robust for damping power oscillation of power system. In this paper, UPFC model based on the VSC was analysed and applied to power-flow control and stability analysis. The control strategy based on the energy function is adopted for damping power oscillation of power system. The effectiveness of proposed control strategy was verified by simulation study

• Journal of Power Electronics
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• v.11 no.3
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• pp.256-263
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• 2011

This paper utilizes free oscillation and energy injection principles to generate and control the high frequency current in the primary track of a contactless power transfer system. Here the primary power inverter maintains natural resonance while ensuring near constant current magnitude in the primary track as required for multiple independent loads. Such energy injection controllers exhibit low switching frequency and achieve ZCS (Zero Current Switching) by detecting the high frequency current, thus the switching stress, power losses and EMI of the inverter are low. An example full bridge topology is investigated for a contactless power transfer system with multiple pickups. Theoretical analysis, simulation and experimental results show that the proposed system has a fast and smooth start-up transient response. The output track current is fully controllable with a sufficiently good waveform for contactless power transfer applications.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.12-13
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• 2006

In this paper, RCF(Resistive Companion Form) analysis method which is used to analyze small signal stability problems of non-continuous systems including switching device. The RCF analysis method are applied to the power systems with the thyristor controled FACTS equipments such as TCSC. As a result of simulation, the RCF method is very powerful to calculate the oscillation modes exactly after the switching operations, and useful to analyze the small signal stability of power systems with switching devices such as FACTS equipments. As an applicable example of the RCF method in power system, the one machine infinite bus system including TCSC at generator terminal bus is investigated and the results proved that variations of oscillation modes after periodic switching operations of TCSC can be calculated exactly.