• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.82-91
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• 2014

The combined generator system by integrating several renewable energy sources can share the electrical infrastructure and therefore have the advantage of constructing not only the transmission system but also the power conversion system. Among the various combined renewable system, the wind power and wave power has a high possibility of future growth due to the economic feasibility in offshore environment. This kind of large-scale combined systems might be follow the determination by the transmission system operator's directions and control the output profile by focusing at PCC. However, both renewable energies are depend on the unpredictable environmental variation; it is needed to do the compensation devices. In this paper, the ESS compensation plan is proposed to do output determination of the combined generator system by paying attention to active power of utility grid with the analysis of the controllable elements of the wind and wave power generator. The improvement of the new application technique of the combined system is confirmed through using the PSCAD/EMTDC. The entire simulation process was designed by adopting the active power control according to the reference signal of TSO.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.5
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• pp.225-233
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• 2001

SIME(SIngle Machine Equivalent) method has been recognized as a useful tool to determine transient stability of power systems. In this paper, SIME method is used to develop the KEPCO transient stability assessment (TSA) tool. A new screening algorithm that can be implemented in SIME method is proposed. The salient feature of the proposed screening algorithm is as follows. First, critical generators are identified by a new index in the early stage of the time domain simulation. Thus, computational time required to find OMIB(One Machine Infinite Bus) can be reduced significantly. Second, clustering critical machines can be performed even in very stable cases. It enables to be avoid extra calculation of time trajectory that is needed in SIME for classifying the stable cases. Finally, using power-angle trajectory and subdividing contingency classification have improved the screening capability. This algorithm is applied to the fast TSA of the KEPCO system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.1
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• pp.24-28
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• 2006

This paper presents a power transfer capability calculation algorithm considering transient stability, The theoretical development is straightforward: dynamic equations are converted to numerically equivalent algebraic equation and then integrated into the standard formulation for power transfer capability calculation. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.185-186
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• 2016

Maximum power point tracking (MPPT) techniques play a big role in improving the efficiency of photovoltaic (PV) system. Among various schemes, the incremental conductance (INC) method is mostly discussed in literature because of its fast response to the rapid irradiation changes and high tracking accuracy. However, the existing INC algorithm has trade-offs between fast dynamic response and steady state stability. This study proposes a novel INC method to meet high efficiency and fast tracking performance at the same time.

• Structural Engineering and Mechanics
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• v.14 no.6
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• pp.661-677
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• 2002

The subject of this investigation is to study the buckling of cross-ply laminated orthotropic cylindrical thin shells with variable elasticity moduli and densities in the thickness direction, under external pressure, which is a power function of time. The dynamic stability and compatibility equations are obtained first. These equations are subsequently reduced to a system of time dependent differential equations with variable coefficients by using Galerkin's method. Finally, the critical dynamic and static loads, the corresponding wave numbers, the dynamic factors, critical time and critical impulse are found analytically by applying a modified form of the Ritz type variational method. The dynamic behavior of cross-ply laminated cylindrical shells is investigated with: a) lamina that present variations in the elasticity moduli and densities, b) different numbers and ordering of layers, and c) external pressures which vary with different powers of time. It is concluded that all these factors contribute to appreciable effects on the critical parameters of the problem in question.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.111-115
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• 1997

ZnO varistors are widely used as surge arresters in power system based on their excellent nonlinearity. The property of power loss of ZnO varistors is related to the thermal stability and their life-spans of ZnO surge arresters. The power losses of ZnO varistors under different temperatures and applied voltages were measured, and the properties of power losses were analyzed. The Artificial Neural Network (ANN) was used to simulate the power losses properties of ZnO varistors which is an adaptive nonlinear dynamic system, and the results calculated by ANN simulating model were in good agreement with the tested ones.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.218-220
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• 2000

In this paper, the problem of the design of an intelligent type precompensator is discussed for the performance improvement of a power system stabilizer(PSS). An advantage of the scheme is that an existing PSS can be easily modified in our control structure simply by adding an adaptive neurofuzzy-based precompensator. The overall system has been tested on a simulation model in different operation conditions. Case studies show the proposed scheme can provide the good damping of the power system over the wide range of operating conditions and improve the dynamic performance of the system.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.38-40
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• 2003

This paper describes the integrated dynamic stability(IDS) program for tuning the power system controllers, such as PSS, AVR and so on. IDS consists of three modules; power flow module, PWRLF, to calculate large scale power system load flow solutions, IDS/PSS module to calculate eigenvalues and frequency response in the range of frequency from 0.2Hz to 2Hz, and IDS/NEA module to calculate eigenvalues in the range of frequency from 5.0Hz to 55Hz. In addition, IDS provides graphic user interface(GUI) in order to let the user handle and analyze the input data and the results of calculation with convenience.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.102-105
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• 1995

In power system stability analysis, modelling of the synchronous machine is necessary and vary important. In this paper, a synchronous machine is modeled and simulated by using Object-Oriented method. The mathematical equations describing the dynamic behavior of the synchronous machine is represented by block diagram and Objected-Oriented Digital Computer Simulater(ODCS). The developed method is tested for a one-machine-to-infinite-bus system, which is accurate and very useful for a multi-machine system simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1647-1656
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• 2013

Although the demand for electricity has been increasing these days, it becomes more difficult to find new sites for large-scale power generation plants near urban areas due to environmental and economic issues. Therefore, new power plants are forced off to rural or desolate coastal areas. As a result, there is significant regional imbalance in power generation and consumption between urban and rural areas in South Korea. This paper investigates the feasibility of high-voltage DC (HVDC) system as a candidate for electric power transmission system from east-coastal sites to metropolitan area. To this end, this paper analyzes transient stability and dynamic impact of a HVDC transmission system and compares the results to conventional high-voltage AC (HVAC) transmission systems via PSS/E simulation. This paper also examines the effect of HVDC system to voltage variation and low-frequency resonance in the neighboring buses in the grid using ESCR(Effective Short Circuit Ratio)과 UIF(Unit Interaction Factor) indices.