• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.251-254
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• 2003

A voltage stability assessment consists of the contingency screening, voltage stability analysis, and counter measures. A widely used index for the voltage stability assessment of power system is the reactive power margin. It shows some factors of voluntariness as following the status of power system and load levels for the target analyzing area. Therefore, it has a demerit that the absolute amounts of reactive power margin is not to be applied by the quantized margin criterion. This paper selects a vulnerable area by assigning the voltage instability for the particular contingency for the selection of vulnerable area in the respect of the investigation of reactive power margin or VQVI as an index of V-Q margin sensitivity in order to overcome the demerit. This will be able to grasp the V-Q margin sensitivity for the target analyzing area by presenting the ratio of power margin between the margin before and after contingency as following the calculation of reactive power margin. The presented method is applied to the voltage stability assessment for the Metropolitan area of 2003 KEPCO summer peak system.

• 전기전자학회논문지
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• 제18권3호
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• pp.313-319
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• 2014

전력계통운영의 목표는 전력시스템의 안정성과 신뢰성을 유지하여 원활한 전력을 공급하는 것이다. 안정적인 전력 공급을 위하여 무효전력과 모선 전압에 대한 고려를 해야 하는데, 모선의 전압을 일정 범위 이내로 유지하기 위하여 커패시터 뱅크를 비롯한 다양한 방안이 사용되고 있다. 본 논문에서는 계통 안정도와 전력공급 신뢰도를 상시키기 위한 하이브리드 타입의 커패시터 뱅크 설계 과정에 대하여 기술하였다. 설계 과정에는 커패시터 뱅크의 용량 산정, 리액터 타입 결정 및 리액터 용량 산정과정이 포함된다. 기존의 커패시터 뱅크의 설계과정과 같이 정상상태 Q-V 해석이나 상정사고 분석과 같은 방법을 통하여 무효전력 마진을 계산하여 저전압이 발생하는 모선에 무효전력 보상량을 산정한다. 그리고 고조파 실측을 통해 산출된 개별 고조파의 성분 크기를 기반으로 직렬 리액터의 크기를 산정하는 방식으로 설계과정을 제안하였다. 논문에서는 제안된 방법을 통하여 고조파의 크기가 감소함을 증명하였으며, 특히 5차와 7차 고조파의 저감에 효율적임을 보여주었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.83-83
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• 2008

Metal-oxide-silicon-on-insulator (MOSOI) structures were fabricated to study the effect caused by reactive ion etching (RIE) and sacrificial oxidation process on silicon-on-insulator (SOI) layer. The MOSOI capacitors with an etch-damaged SOI layer were characterized by capacitance-voltage (C-V) measurements and compared to the sacrificial oxidation treated samples and the reference samples without etching treatment. The measured C-V curves were compared to the numerical results from 2-dimensional (2-D) simulations. The measurements revealed that the profile of C-V curves significantly changes depending on the SOI surface condition of the MOSOI capacitors. The shift in the measured C-V curves, due to the difference of the fixed oxide charge ($Q_f$), together with the numerical simulation analysis and atomic force microscopy (AFM) analysis, allowed extracting the fixed oxide charges ($Q_f$) in the structures as well as 2-D carrier distribution profiles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.556-558
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• 1995

This paper presents a new simplified method for finding the multiple load flow solutions and through their solutions the voltage stability can be evaluated. Line flow($P_{ij}$, $Q_{ij}$) may be formulated with the second-order equations for $V_{i}^{2}$ in polar coordinates or two circle equations for $e_{i}$ and $f_{i}$ in rectangular coordinates. Based on this feature, multiple load flow solutions are calculated with simple works, results of multiple load flow solutions are used for sensitivity analysis of voltage stability. Also, in the case that reactive power sources is considered, method of evaluating the voltage stability is introduced. The proposed method was validated to 2-bus and IEEE 6-bus system.

• KIEE International Transactions on Power Engineering
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• 제3A권3호
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• pp.161-167
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• 2003

This paper presents a study performed to investigate the steady-state operational strategies of UPFCs in the Jeollanam-Do system in Korea. The objective of the study was to determine the UPFC operating points under normal and contingency conditions. The study consists of developing load flow models to simulate different load levels with and without UPFCs in the system, assessing the effectiveness of UPFCs by contingency analysis, and introducing optimal corrective actions for removing voltage problems caused by contingencies. The paper describes analytical tools, models and approach. It also includes analysis and discussion of the study results. The paper contributes to the area of transmission operational studies with FACTS applications.

• 전기학회논문지
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• 제59권6호
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• pp.1011-1016
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• 2010

It is an important issue to electric power system operations that it can reliably supply large-capacity power to consumption area as due to increasing power demand growth. For this purpose, The FACTS equipment based on Power IT technology with the existing mechanical compensators has been applied to power system. Therefore we suggest on this paper that a plan for coordination control of multiple power compensation equipment in order to increase the utilization of each facility and secure operation margin capacity. As the result of simulation, it is possible to cope actively with a suddenly changed power system. This helps greatly for the voltage stability and supply reliability in a suddenly changed power system.