• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1150-1156
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• 2008

This paper introduces the PC clustering of the SIMD structure for a distributed processing of on-line contingency to assess a static security of a power system. To execute on-line contingency analysis of a large-scale power system, we need to use high-speed execution device. Therefore, we constructed PC-cluster system using PC clustering method of the SIMD structure and applied to a power system, which relatively shows high quality on the high-speed execution and has a low price. SIMD(single instruction stream, multiple data stream) is a structure that processes are controlled by one signal. The PC cluster system is consisting of 8 PCs. Each PC employs the 2 GHz Pentium 4 CPU and is connected with the others through ethernet switch based fast ethernet. Also, we consider N-1 line contingency that have high potentiality of occurrence realistically. We propose the distributed process algorithm of the SIMD structure for reducing too much execution time on the on-line N-1 line contingency analysis in the large-scale power system. And we have verified a usefulness of the proposed algorithm and the constructed PC cluster system through IEEE 39 and 118 bus system.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.438-442
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• 2009

Voltage instability is a phenomenon that could occur in power systems due to stressed conditions. The result would be an occurrence of voltage collapse leading to total blackout of the system. Therefore, voltage collapse prediction is an important part of power system planning and operation, and can help ensure that voltage collapse due to voltage instability is avoided. Line outages in power systems may also cause voltage collapse, thereby implying the contingency in the system. Contingency problems caused by line outages have been identified as one of the main causes of voltage instability in power systems. This paper presents a new technique for contingency ranking based on voltage stability conditions in power systems. A new line stability index was formulated and used to identify the critical line outages and sensitive lines in the system. Line outage contingency ranking was performed on several loading conditions in order to identify the effect of an increase in loading to critical line outages. Correlation studies on the results obtained from contingency ranking and voltage stability analysis were also conducted, and it was found that line outages in weak lines would cause voltage instability conditions in a system. Subsequently, using the results from the contingency ranking, weak areas in the system can be identified. The proposed contingency ranking technique was tested on the IEEE reliability test system.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.694-703
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• 2013

In electric power system, the line stability indices adopted in most of the instances laid stress on variation of reactive power than real power variation of the transmission line. In this paper, a proposal is made with the formulation of a New Voltage Stability Index (NVSI) which originates from the equation of a two bus network, neglecting the resistance of transmission line, resulting in appreciable variations in both real and reactive loading. The efficacy of the index and fuzzy based load flow are validated with IEEE 30 bus and Tamil Nadu Electricity Board (TNEB) 69 bus system, a practical system in India. The results could prove that the identification of weak bus and critical line in both systems is effectively done. The weak area of the practical system and the contingency ranking with overloading either line or generator outages are found by conducting contingency analysis using NVSI.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.149-155
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• 2004

This paper presents how to find proper operating points of FACTS devices to enhance the steady-state security level considering line contigency analysis. Three generic types of FACTS devices such as series controllers, shunt controllers, and series-shunt controllers are introduced and applied to moximize a security margin and to minimize security indices. Security indices related to line flows and bus voltages are utilized and minimized iteratively in this paper. Contingency analysis is performed to detect the most severe single line fault. In various load conditions, FACTS devices are tested to establish appropriate preventive or corrective action without generation re-dispatching or load shedding. The FACTS operation scheme is verified on the IEEE 57-bus system in a line-faulted contingency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.994-1001
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• 2018

In this paper, to studied about future power system construction using PSS / E-Python API. Python-based future system automatical construction methods and modeling of renewable sources. it confirmed the stability of the powert system for each renewable area by calculating the weighted short circuit ratio (WSCR) index. it calculated the short circuit ratio (SCR) and selected the transmission line linkage scenario to improve the stability of vulnerable areas. it confirmed the WSCR index improvement through the selected transmission line linkage of scenario, and analyzed the stability of the renewable power system applying the scenario. It describes Facts and Shunt devices adjustment for the load flow convergence. It describes the stable methed of the bus voltage through the transformer Ratio Tap adjustment. By performing PSS/E ASCC using the Python it was performed three-phase short circuit fault capacity analysis, it is confirmed whether excess of the fault current circuit breaker capacity. In order to contingency accident analysis, it have described the generation of one or two line list of each areas using the Python. The list is used to contingency analysis and describe the soluted of the transmission line overload through comparison before and after adding the scenario line.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.5
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• pp.309-318
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• 1987

In the on-line security analysis of power system, Automatic Contingency Selection (ACS) is commonly used to reduce the number of contingency cases which will be evaluated in detail. This paper describes a fast and reliable ACS method which adopts DC load flow in conjunction with compensation theorem to improve execution time, and applies severity performance index, divided on each limit level for considering overload rate, to make reliable contingency ranking. The method has been tested in IEEE 25 bus system and KEPCO 130 bus actual power system. The results of these tests verify its superiority to both the execution time and reliability, and illustrate its effectiveness for the practical use.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.9
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• pp.1171-1179
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• 2014

ISO(Independent System Operator) or TSO(Transmission System Operator) use power system analysis program to simulate contingency analysis and remedial actions to operate power system stably. Generally, power system analysis program provides automated analysis functions(or modules) to deal with wide area power system. However, because of missed contingency cases, automated contingency analysis has no practical use or has limitation. And in case of remedial action, it doesn't support automated function or takes a lot of times to study, because of simulation in manual for each cases. This paper suggests that new relation with buses and transmission line properties of power system DB used for power system analysis program to simulate automated contingency including all contingency cases needed in the field without missed cases. And it proposes automated remedial action scheme based on practical approach analysis to alleviate overloading or voltage problems. Finally it deals with automated contingency/remedial action analysis(automated scheduled outage) program which is developed by KEPCO and its performance and proposed schemes are proven by case study for real Korean power system data.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.2
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• pp.111-118
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• 1990

This paper presents a new algorithm of contingency analysis and countermeasure to alleviate the line overloads for electric power systems. In this algorithm, the inverse matrix of the new Jacobian matrix when a contingency occurs, in fastly calculated using the house-holder's Inverse Matrix Modification Lamma (IMML) with the original factor table. The generation outputs are firstly adjusted to alleviate all line overloads occurred by the contingency without tripping loads. If the generation adjustment is not enough anymore to alleviate line overloads, then the control of bus injection power is recommended to quickly alleviate remaining overloads with minimum amount of load tripping and generation read-justing at the termination busbars of the overload lines. The proposed algorithm has been validated in tests on the 6 busbar test system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.127-137
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• 2003

Contingency analysis is one of the most important tasks encountered by planning and operation of lafe scale power systems. This paper describes a new contingency analysis methods for small signal security assessment based on the eigen-sensitivity/perturbation of the electromechanical oscillation modes. The eigen-sensitivity/perturbation with respect to line suceptances and controller parameters can he used to find possible sources of the system instability, and to select contingency for small signal stability. Also, the contingency selection to identify critical generators for MW changes can be obtained by computing the relative movement of the system oscillation modes. The proposed algorithm has been successfully tested on the KEPCO systems which is comprised of 791-bus, 1575-branch and program PSS/E

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.363-370
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• 2003

This paper presents the analysis of the load transfer capacity and study of conductor size for variable contingencies in distribution systems. The operation capacity of feeders was changed to improve operation efficiency in KEPCO, considerations for contingencies are still based on the previous capacity. In order to cope with the changes such as operation capacity, it is necessary to study whether the present "contingency support criteria" is reasonable or not, also to confirm the whether the present criteria should be improved or not. We analyze the load transfer capacity and conductor size on a distribution system for contingency levels such as the substation-level, bank-level, feeder-level, and zone-level.one-level.