• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.568-570
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• 1995

Nowdays, voltage stability is well recognized as an important problem. It is well known that voltage stability is influenced by the characteristics of load. Up to present,voltage stability researches were done by the static load modeling, but it is needed that the precise analysis by the view point of dynamic load modeling. In this paper, with induction motor as dynamic load, using modal performance measure, optimal value of tcsc is determined.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.797-799
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• 1996

This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these equations become one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack bus or generator bus, which is specified voltage magnitude, it becomes One equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, solutions are obtained with simple computation. Solutions obtained are used for evaluating of voltage stability through sensitivity analysis. Also, considering of reactive power source, method for evaluating the voltage stability is introduced. The proposed method was validated to 2-bus and IEEE 6-bus system.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.158-161
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• 2004

This paper presents practical applications of reactive power and voltage planning to obtain voltage stability and operational voltage level for 2005 year summer peak Korea power system. It also describes the new electric facilities, operation criteria, voltage levels, MVAr flows, reactive power reserves in each control area. And reactive compensation devices are installed to maintain established voltage levels and stability margins. This simulation results show the improvement of voltage levels and the increase of reactive margins & interface flow margins. Finally, the paper reports the necessity of dynamic reactive reserves. It can be applied to analysis reactive compensation requirements and P-V & V-Q curves by PSS/E & VSAT.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.48-56
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• 2015

There is a wide variety of system and applications in the power system. However, they have compatibility issues because they use different data standard and communication method. With the introduction of the smart grid, power system has been grow and diversified. Therefore power system need to be compatible with each other and the interoperability between applications is increasingly important. Thus, the IEC established IEC61970 and CIM Standard data exchange model for interoperability and system integration. Server-Client system was constructed which using CIM HSDA(Part4), a standard communication model, presented in IEC 619710. Also, self-developed real-time voltage stability analysis application and contingency analysis application was used. CIM HSDA was used for data input and real-time analysis. Tolerance of result which is in the range of allowable derived by Perform real-time voltage stability and contingency analysis of Jeju power system, and then compare it's result with PSS/E result.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.112-116
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• 1996

This paper presents the study results of FACTS application plan for transmission capability Enhancement. Power transfer across the KEPCO system resulting from a concentration of load in the Kyung-In area are subject to thermal, voltage and stability constrains. In the analysis study of the KEPCO system in 2000 and 2006 year. voltage stability analysis. modal analysis and dynamic stability were simulated by the power system analysis tools(VSTAB, PSS/E).

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.7
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• pp.337-344
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• 2005

An energy function is derived on the basis of the EMM(Equivalent Mechanical Model) to take account of the effects of tap changer, and then the VC(Voltage Collapse) criteria is proposed to predict the voltage collapse in Power systems. The VC criterion can be evaluated by using the energy margin given by the energy gap between UEP(Unstable Equilibrium Point) and SEP(Stable Equilibrium Point) of the energy function adopted, in which it is noted that the energy contour should be considered due to energy discontinuity associated with tap changing. This paper shows that the proposed VC criterion improves the accuracy of voltage stability analysis with application to a two-bus sample system.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.411-413
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• 2005

Static approaches usually employed in voltage stability analysis are based on the pre-determined scenarios of varying load and generation patterns. Thus, even though the approaches are applied to the same system condition, one may obtain different voltage instability phenomena using different scenarios. In the stage of concrete control strategy determination against voltage instability, dynamic approaches with full-time and/or quasi steady-state simulations need to be applied in order to confirm the effectiveness of the established control strategies. This paper describes the ULTC and dynamic load models, and discusses characteristics of the models.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1733-1740
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• 2010

KPX(Korea Power Exchange) predicts that summer peak load will be 70,700MW and system overload will be 150% from contingency analysis. This paper presents a method to operate power system at 2010 summer peak. about equipment variation, power system variation, analysis results of voltage stability, and the method to relief overload by comparing 2009 and 2010. Especially, transmission constraints to prevent global contingency in Korea power system and the role of SPS(Special Protection System) to prevent voltage collapse when fault occurs are introduced.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.32-41
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• 1992

This paper presents a comprehensive study on the stability of several control schemes for the induction motor driven by current source inverters. A stator voltage controlled current source inverter drive system without a speed sensor is investigated in order to find appropriate control schemes, which are primarily based on direct or, alternatively, indirect frequency control scheme. It can be seen, especially that an introduction of the indirect frequency control method improves the inherent instability of the current source inverter drive system for the induction motor. The overall control systems with either voltage control loop or current and voltage control loops in addition to each frequency control scheme, are analyzed by utilizing the root locus method and simulated by computer to show the validity of this analysis.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.3
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• pp.178-182
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• 2016

FIDVR(Fault Induced Delayed Voltage Recovery) is a phenomenon that recovery of the system voltage level delays after the fault. Cause of FIDVR phenomenon is motor load characteristic about voltage and reactive power. In low voltage condition, the motor go to stall state that consume large amount of reactive power. As a result, the voltage recovery problem is that of repeated occurrences of sustained low voltage following faults on the system. In this paper, analysis the characteristics of the motor load. And using the korean power system actual data, perform a case studies to voltage delay recovery phenomenon alleviation method. Change of each parameters by analyzing the effect on system and selecting an influence parameter. In addition, dynamic characteristic analysis of the resulting difference in the proportion by the motor load in power systems, considering the effect on the voltage stability.