• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.371-377
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• 2005

Congestion problems of transmission lines are very important research issues in power system operations. Load curtailment is one of the ways to solve congestion problems by a major contingency. A systematic and effective mechanism for load shedding has been developed by investigating congestion distribution factors and the direct load control program. In this paper, a load shedding algorithm using linear programming for congestion problems by a major contingency is presented. In order to show the effectiveness of the proposed algorithm, it has been tested on the 6-bus sample system and the power system of Korea, and their results are presented.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.1
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• pp.1-6
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• 2014

An electric power system sometimes fails because of disturbances that occur unexpectedly, such as the uncontrolled loss of load that developed from cascading blackout. Which make stability through a little of under voltage load shedding should work. The development of phasor measurement unit(PMU) makes network supervision possible. The information obtained from PMU is synchronized by global positioning system(GPS). There are many real-time algorithms which are monitoring the voltage stability. This paper presents the study on the VILS(Voltage Instability Load Shedding) using PMU data. This algorithm computes Voltage Stability Margin Index(VSMI) continuously to track the voltage stability margin at local bus level. The VSMI is expressed as active and reactive power. The VSMI is used as an criterion for load shedding. In order to examine the algorithm is effective, applied to KEPCO system.

• Journal of Computing Science and Engineering
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• v.5 no.4
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• pp.294-304
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• 2011

Enhancing continuous queries over data streams with temporal functions and predicates enriches the expressive power of those queries. While traditional continuous queries retrieve only the values of attributes, temporal continuous queries retrieve the valid time intervals of those values as well. Correctly evaluating such queries requires the coalescing of adjacent timestamps for value-equivalent tuples prior to evaluating temporal functions and predicates. For many stream applications, the available computing resources may be too limited to produce exact query results. These limitations are commonly addressed through load shedding and produce approximated query results. There have been many load shedding mechanisms proposed so far, but for temporal continuous queries, the presence of coalescing makes theses existing methods unsuitable. In this paper, we propose a new accuracy metric and load shedding algorithm that are suitable for temporal query processing when memory is insufficient. The accuracy metric uses a combination of the Jaccard coefficient to measure the accuracy of attribute values and $\mathcal{PQI}$ interval orders to measure the accuracy of the valid time intervals in the approximate query result. The algorithm employs a greedy strategy combining two objectives reflecting the two accuracy metrics (i.e., value and interval). In the performance study, the proposed greedy algorithm outperforms a conventional random load shedding algorithm by up to an order of magnitude in its achieved accuracy.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.366-369
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• 1991

Load shedding algorithm has been developed using heuristic search and D.C flow method. The line flow error with a D.C method was improved in this paper. Minimization of load shedding was obtained with heuristic search method. Although analytical method have been mixed with expert algorithm the C language fitted well for this purpose.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.33-39
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• 1997

In this paper we proposed a new traffic load shedding scheme which maximizes the throughput of traffic control by decreasing the load of the hot-spot cell using minimum load cell selection (MLCS) algorithm and deployed control flow of calls to define characteristic for hadoff region. we compared the performance of the random shedding approach with that of the proposed algorithm. The results of simulation show that MLCS algorithm minimizes the cal blocking rate under a high-density traffic compared to the random shedding scheme.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.3
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• pp.270-273
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• 1995

This paper proposes an optimal load shedding algorithm by which the system loss can be minimized when the load shedding is unavoidable in case of severe contingency such as the outage of key generators or lines. Shedding load .DELTA.S = .DELTA.P + J.DELTA.Q(MVA) is performed on the weakest bus (on the view of voltage stability), step by step, by the priority of the I.DELTA. = SQRT(.lambda.$\_$P/$\^$2/ + .lambda.$\_$Q/$\^$2/) index given for each load bus, where .lambda.$\_$P/ and .lambda.$\_$Q/ are the sensitivity indices representing the system loss variation versus active and reactive power change of the bus load bus. All loads are assumed to be constant power loads for convenience. A 5 bus sample system proves the effectiveness of the algorithm proposed.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.244-245
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• 2011

In this paper, the algorithm for detecting load shedding based on Wavelet Singular Value Decomposition(WSVD) is proposed. WSVD is method of signal processing which combine Wavelet Transform(WT) and Singular Value Decomposition(SVD) to analyze transients in power system. 345kV Busan transmission system is modeled by EMTP-RV and simulations according to successive change of load capability are conducted. This paper analyzes characteristics of WSVD by using simulation results and proposes algorithm for detecting load shedding.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.30-32
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• 2005

Due to a major contingency, the congestion of the transmission may happen in power systems. In order to manage the congestion problem, load curtailment is one of the ways to resolve the problem. It is essential that the systematic and effective mechanism for the load shedding be developed. In this paper, the load shedding algorithm using the linear programming for the congestion problems by a major contingency is proposed. The simulations of the proposed algorithm are performed for the power system of Korea and their results are presented.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.899-901
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• 1998

Continuation power flow is a tool that can trace the path of the solution from the base stable solution. However, the base stable solution cannot be calculated when the initial system load is too large to operate at a stable operating point. This case is called as unsolvable case. This paper presents implementation of the optimal load shedding algorithm on continuation power flow. It performs steady-state analysis of power systems at unsolvable case that can occur in contingency analysis. Numerical simulation on 20-bus test system demonstrates that the continuation power flow applying the optimal load shedding algorithm is robust at solvable and unsolvable cases.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.391-392
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• 2016

A phase shedding control algorithm to increase efficiency of 3-Phase interleaved boost converter is proposed. Conventional interleaved converter has low efficiency under the light load condition. In this paper, the number of phase is controlled in accordance with the load condition to increase the light load efficiency. The validity of proposed phase control algorithm is verified by simulation results based on measured efficiency.