• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.72_73
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• 2009

The industrial power system has the radial plant distribution system and domestic generators to supply the essential loads. When the system is isolated from the utility tie line, the system frequency drops resulting in the trip of generators. The load shedding scheme shall be properly designed to secure the essential load. In this paper two kinds of load shedding schemes, those are, the Fast Act Load Shedding(FALS) and Under Frequency Load Shedding(UFLS) are simulated and compared taking an example of petrochemical gas separation plant.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1214-1220
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• 2010

This paper proposes an efficient under frequency relay load shedding scheme for the korea power system which is more than two times than the system size and its capacity of the power system 10 years ago. The proposed method is keeping the power system stability and supports for the operating system during critical situations such as big disturbances and unstable in supply and demand. In order to determine the number of load shedding steps, the load to be shed per step, and frequency level, it is necessary to investigate and analyze maximum losses of generation due to the biggest contingency, maximum system overload, maximum keeping frequency, maximum load to be shed, and recovery frequency. The proposed method is applied to Off-peak load(25,400MW) and Peak load(62,290MW) of Korea Electric Power Corporation to demonstrate its effectiveness.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.6
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• pp.301-306
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• 2003

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 natural 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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• 2002.11b
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• pp.121-122
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• 2002

When a power system experiences a serious disturbance on insufficient power, the system frequency may drop. For system frequency will be maintain standard value, under_frequency relay will reconstruct balance of power and load by load shedding. Currently load shedding scheme is due to establishment plan by fixed scenario. Where compare current scheme with past scheme, system frequency should be recovered by load shedding using rate of frequency decline. This paper suggests the dynamic load shedding scheme by using the rate of change of frequency when The Korea Electric power system is happened the large disturbance.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.446-452
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• 2013

Under frequency load shedding (UFLS) is an effective way to prevent system blackout after a serious disturbance occurs in a power system. A novel centralized adaptive under frequency load shedding (AUFLS) scheme using the synchronous phase measurement unit (PMU) is proposed in this paper. Two main stages are consisted of in the developed technique. In the first stage, the active power deficit is estimated by using the simplest expression of the generator swing equation and static load model since the frequency, voltages and their rate of change can be obtained by means of measurements in real-time from various devices such as phase measurement units. In the second stage, the UFLS schemes are adapted to the estimated magnitude based on the presented model. The effectiveness of the proposed AUFLS scheme is investigated simulating different disturbance in IEEE 10-generator 39-bus New England test system.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.34-37
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• 2003

The frequency of power system will change when the load-generation equilibrium is disturbed. Insufficiency of generation from the imbalance between load and generation decreases the power system frequency. In case of the severe emergency, the under frequency load shedding scheme is applied for the power system defense plan. In this paper, we analyzed the dynamic characteristics of under frequency load shedding using new Transient Security Assessment Tool ; TSAT. We applied the actual UFLS scheme to these studies and considered the possible contingency.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.103-109
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• 2004

This paper has presented, taking an example of a gas separation plant, dynamic analysis on frequency decline caused by the over-loading at the generator and the knee point causing voltage instability due to reactive power required by re-acceleration of large induction motors, resulting in phenomena of failure in the conventional frequency load shedding. In order to resolve the voltage instability problem, a design of load shedding system employing under-voltage relays has been proposed to the industrial power system containing large induction motors in addition to the conventional load shedding employing frequency relays. For the purpose of dynamic analysis, models of gas turbine and governor, synchronous generator, brushless exciter, and induction motor are introduced.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.2
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• pp.35-41
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• 1995

This paper proposes an adaptive methodology for setting of the underfrequency relays that is based on the initial rate of change of the frequency decline to protect for excess frequency decline of power system under large generator outage. The strategy of the load shedding is as follows : Let the load shedding of the first step occur when the frequency reaches 59.5 (Hz), and the load shedding power of this first and second step be one half of the total "Static Load Shed" value for any given disturbance size based on the initial rate of change of the frequency. As a results, it is verified that the use of the proposed method is more efficient than the conventional method in the characteristic of the frequency recovery. recovery.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.61-65
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• 2000

This paper presents the load shedding case studies and recommendations of load shedding scheme For improving the reliability to suit the requirements of LG-Caltex refinery plant power sγstem. It is recommended for LG-Caltex to decrease the total generation for the economic dispatch. When the LG-Caltex refinery is isolated from KEPCO utility system, the proper load shedding scheme should be implemented since total generation in LG-Caltex refinery plant is less than the load demand. According to the studies carried out the logic-based load shedding is recommended as the main protection scheme, with the combination of the under-frequency relay load shedding.

• 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.