• 전기학회논문지P
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• 제67권4호
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• pp.208-213
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• 2018

In this paper, we studied the control strategy of applying STATCOM(static synchronous compensator) to mitigate the FIDVR(fault induced delayed voltage recovery) phenomenon. The proportion of motor loads is gradually increasing which might affect power system stability. Excessive reactive power consumption by the stall of the motor loads causes FIDVR phenomenon. In addition, the low inertia of the small HVAC(heating, ventilation and air conditioner) unit will not separate itself in the event of a contingency, causing system instability. For this reason, we have developed a control strategy that utilizes STATCOM efficiently through static and dynamic analysis. Case studies on a Korean power system have validated the performance of the proposed scheme under severe contingency scenarios. The results have verified that the proposed strategy can effectively mitigate FIDVR and improve the stability and reliability of the system.

• 조명전기설비학회논문지
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• 제18권3호
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• pp.149-155
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• 2004

본 논문에서는 상정사고 해석을 통해 결정된 가장 심각한 단일 선로고장에 대하여 부하차단이나 재급전을 하지 않고, 유연송전기기의 운전만으로 안전도를 향상시켜 이를 극복할 수 있는 방법을 제시하였다. 즉, 직렬, 병렬, 직병렬보상기기 등 유연송전기기의 각 종류별로 정적 안전도 여유를 최대화하고 안전도 지수를 최소화하는 방법을 개발하였고, 이를 통하여 각 유연송전기기의 최적 운전점을 결정하는 방법을 개발하였다. 여기서, 정적 안전도 지수는 선로 조류 및 모선 전압에 관한 안전도를 정량화하여 식으로 나타낸 것이다. 안전도 지수가 작아지면 안전도 여유는 커지는데, 본 논문에서는 안전도 지수를 반복계산법으로 최소화하였다. 본 논문에서는 제안한 방법은 IEEE 57모션개통에 적용하여 제안된 방법의 정당성을 수치적으로 입증하였다.

• 대한전기학회논문지
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• 제43권2호
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• pp.179-188
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• 1994

This paper deals with implementation of an expert system to obtain an optimal plan of load transfer for fault restoration with the capability of security monitoring and assessment in distribution systems. Based on the technique of load transfer tree analysis, the proposed expert system can afford to assist system operators in proposing an optimal plan of load transfer for fault restoration, In paticular, an application of the proposed ES to practical distribution systems yields an optimal load transfer plan which ensures system security by considering security assessment for contingency of feeders and main transformers in the knowledge based sense.

• 전기학회논문지
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• 제57권2호
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• pp.155-163
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• 2008

This paper presents a novel framework for analysis of power system wide-area blackout based on so called fault cascading scenarios. For a given power system operating state, "triggering" faults or a "seed faults" are chosen based on the probabilities estimated from the hazard rates. The fault probabilities reflect both the load and the weather conditions. Effects of hidden failures in protection systems are also reflected in establishing the fault propagation scenarios since they are one of the major causes for the wide-area blackouts. A tree type data structure called a PS-BEST(Power System Blackout Event Scenario Tree) is proposed for construction of the fault cascading scenarios, in which nodes represent various power system operating states and the arcs are the events causing transitions between the states. Arcs can be either probabilistic or deterministic. For a given initial fault, the total probability of leading to wide-area blackout is estimated by aggregating the individual probability of each fault sequence route leading to wide-area blackout. A case study is performed on the IEEE RTS-79(24 bus) system based on the fault data presented by the North American Electrical Reliability Council(NERC). Test results demonstrate the potentials and the effectiveness of the proposed technique for the future wide-area blackout analysis.

• 전기학회논문지
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• 제57권6호
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• pp.944-950
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• 2008

When small cogenerators are operated in connected with power system, there are many positive aspects such as the reduction of power plant construction, making a improvement of power security etc. At the same time, there are some negative effects or difficulties such as we should make sure of protective coordination, especially, Actually these are not fault, but it is likely to consider the current as the fault. This is one of major causes of malfunctions for protective relays in power distribution system which is including interconnection point. Thus, in this paper, We showed that the directional protection is necessary to the dispersed generation system which is including connection point. We also executed contingency analysis to find out the magnitude of fault current and direction which are classified by fault points, length of line and kinds of faults using ETAP power system analysis program.

• 전기학회논문지
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• 제60권1호
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• pp.36-42
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• 2011

This paper mainly proposes the protective coordination scheme of the microgrid system. The microgrid protection is identical to the conventional protection system separating the normal part and contingency part to reduce damage when the contingency occur at power cables, facilities. But they are different in the protection type. The conventional protection system only considers unidirectional current. However the microgrid protection should be considered not only unidirectional current but also backfeed current because various microsources and loads are installed in the microgrid system. In case the contingency occurs in microsource, when microgrid is interconnected to grid, the protection system should be configured to not separate microgrid from grid before the microsource is isolated to microgrid. And in case of fault occur in power system, the microsources should not isolated to microgrid before the static switch at PCC is tripped to separate from power system. Considering these characteristic of microgird, this paper proposes the protective coordination scheme of microgrid and implemented the on-line real time monitoring system. Especially in case the microgrid is connected to low voltage distribution system with 220/380V voltage level, the proposed protection method with power IT technology can solve the problems when the existing protective devices only applied to the microgrid system.

• 전기전자학회논문지
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• 제22권3호
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• pp.733-737
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• 2018

본 논문에서는 신재생 발전원의 추가에 따라 계통에 미치는 영향에 관하여 서술하였다. 계통의 안정도 검토를 위해, PSS/E S/W을 이용하여 계통 해석을 수행하였다. 정상상태 조류 계산을 통한 선로 과부하 검토 및 고장 용량 해석을 통한 고장 전류초과여부 및 상정고장 해석을 통한 선로 과부하 여부를 확인하였다. 다이나믹 시뮬레이션을 통해 계통의 동적안정도를 확인하였다. 신재생 발전기 추가에 따른 계통 해석은 전력계통 신뢰도 및 전기품질 유지기준에 따라 해석을 수행하였다.

• 전기학회논문지
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• 제59권10호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.254-255
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• 2011

This paper presents a method to analysis the effect for integrating Sihwa tidal power into power systems. Especially, power flow, fault current, voltage and contingency of sihwa tidal power plant area are calculated and the generation characteristics of tidal machine are analyzed.

• 전기학회논문지P
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• 제65권1호
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• pp.1-6
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• 2016

Recently, proportion of the induction motor load is gradually increased. When a contingency in the power systems, it has been discovered phenomenon that the voltage is delayed recover caused mechanical characteristics of the induction motor load. It can be a serious impact on the voltage stability of the power system considering induction motor load. The scheme to mitigate this phenomenon tripping off the motors to prevent voltage drop and delayed voltage recovery on the load demand side. Fault induced delayed voltage recovery phenomenon is caused by stalling of small induction motor load in transmission level contingencies. In this paper, fault induced delayed voltage recovery phenomenon mitigation method implementation under voltage load shedding on the korean power system considering induction motor load.