• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.845-851
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• 2015

Load shedding is a last measure to avoid nationwide cascading collapses of power system by removing the pre-determined amount of loads from the main grid. In Korea, SPS(Special Protection System) is prepared to keep the power system stability from the extreme contingency of the critical transmission line losses. Among them, we need to pay attention to 765kV T/L’s because they have great influence on the total system stability. According to the present SPS operating guide, the total loads of 1,500MW should be removed through 2 step under-voltage load shedding(UVLS) scheme in case of 765kV T/L’s contingencies. However, it is not clear to defined how to determine the typical load reduction amounts for each case. This paper proposes a method to estimate appropriate amounts of load shed for 765kV T/L’s contingencies by analyzing the relevant national and international standards.

• 전기의세계
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• v.28 no.5
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• pp.49-55
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• 1979

During severe emergencies which result in insufficient generation to meet load, an automatic load shedding method considering the spinning and operating reserve can establish the optimum system operation. This paper presents methods and results of a study on the optimum operating scheme with spinning and operating reserve power in case of outage of large generator units to prevent frequency decay and continue stable operation. This study covers following three parts 1) Analysis of spinning reserve characteristics 2) Determination of operating reserve requirements 3) Development of the optimum load shedding programs By this study the optimum system operating method was recommended for reliable operation of power system.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1115-1117
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• 1997

This paper proposes the automatic load shedding program using estimated power outage amount. Power outage amount estimation is implemented by the inverse problem analysis.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1079-1088
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• 2018

A line overload emergency control strategy based on the source-load synergy coefficient is proposed in this paper. First, the definition of the source-load synergy coefficient is introduced. When line overload is detected, the source-load branch synergy coefficient and source-load distribution synergy coefficient are calculated according to the real-time operation mode of the system. Second, the generator tripping and load shedding control node set is determined according to the source-load branch synergy coefficient. And then, according to the line overload condition, the control quantity of each control node is determined using the Double Fitness Particle Swarm Optimization (DFPSO), with minimum system economic loss as the objective function. Thus load shedding for the overloaded line could be realized. On this basis, in order to guarantee continuous and reliable power supply, on the condition that no new line overload is caused, some of the untripped generators are selected according to the source-load distribution synergy coefficient to increase power output. Thus power supply could be restored to some of the shedded loads, and the economic loss caused by emergency control could be minimized. Simulation tests on the IEEE 10-machine 39-bus system verify the effectiveness and feasibility of the proposed strategy.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.289-291
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• 2002

When a bulk power system experiences a serious disturbance or heavy load trip, the system frequency may drop and even collapse if the total generating power does not supply the system demand sufficiently. Since an isolated power system possesses a lower inertia and comes with limited reserves, the load shedding by under frequency relay becomes an important strategy to keep system frequency. This paper presents a scheme to determine the load shedding criteria by using the rate of change of frequency when the large disturbance happens.

• Proceedings of the KIEE Conference
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• summer
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• pp.162-164
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• 2004

Electrical power peak demand of Republic of Korea is annually growing and the peak demand has occurred in the summer. It is difficult that we handle with constructing power plants and increasing generation capacity to cope with a suddenly increased demand due to the cost problem, difficulty to find the new plant site, and the spread of the NIMBY. The alternative of the above problem is to efficiently manage demand of electrical power. Accordingly, load shedding of a section of demand side management is investigated. First we surveyed a trend of research in the domestic and overseas, for load curtailment and demand response program. After reviewing several demand response programs, the future research direction for load shedding in emergency and normal operation is introduced.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.83-91
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• 2015

This paper presents preventive and emergency control measures for on line transient stability (security) enhancement. For insecure operating state, generation rescheduling based on a real power generation shift factor (RPGSF) is proposed as a preventive control measure to bring the system back to secure operating state. For emergency operating state, two emergency control strategies namely generator shedding and load shedding have been developed. The proposed emergency control strategies are based on voltage magnitudes and rotor trajectories data available through Phasor Measurement Units (PMUs) installed in the systems. The effectiveness of the proposed approach has been investigated on IEEE-39 bus test system under different contingency and fault conditions and application results are presented.

• 전기의세계
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• v.24 no.2
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• pp.84-91
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• 1975

This paper describes the results of a study for the system characteristics, especislly for the abnormal frequency drop of power system, when a large generation unit such as Kori Nuclear 1 (595MW) pulls out from the system. The automatic load shedding method now adopted in our system was re-studied to ameliorate the above problem. From the results of the study, a new under-frequency relay with an element for detecting the slope of frequency change and with time delay element to raise the lowered frequency to a desired value, was found to be effective, and should be purchased and utilized. By this study, an optimal and concrete load shedding method was recommended for reliable operation of power system.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.61-63
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• 1993

This parer propose an adaptive methodlogy for setting of the underfrequency relays that is based on the initial rate of change of the frequency at the relay. During severe emergencies which result in insufficient power generation to meet load, an automatic load shedding program throughout the affected area can prevent total collapse. To avoid this kind of insufficient power generation, load shedding relays are often applied throughput the system to provide a means of helping balance the load to the remaining generation. Comparing, it has been found that the use of the proposed method for the amount and the timing of load shed more efficiently than the conventional method.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.70-72
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• 1993

This paper presents an expert system that sheds loads considering priority in the localized SCADA power systems during an emergency states. The proposed algorithm uses neural networks to detect local load shedding location and heuristic rules to determine load shedding amounts. The proposed expert system is demonatrated at one of the model system which incorporates two localized SCADA power system. It is operated under workstation.