• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1482-1488
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• 2014

The reliability evaluation of the electrical distribution networks (EDN) requires sufficient consideration of the effects of planned outages. The planned outages of the EDN can be divided, by outage models and their effects on the reliability into two major categories: by equipment and by feeder. After studying the characteristics of different categories of planned outages, this paper expands the classification of load points by outage time from 4 types to 7 types and defines corresponding reliability parameters for the different types. By using the section algorithm, this paper proposes a reliability evaluation technique of EDN considering equipment random failures and two categories of planned outages. The proposed technique has been applied to the RBTS-BUS6 test system and some practical EDNs in China. The study results demonstrate that the proposed technique is of higher practical value and can be used for evaluating the reliability performance of EDN more efficiently considering the planned outages.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.164-176
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• 1991

This paper considers the model of a k-out-of-n :G system with non-identical components which are subject to both forced and planned outages. For the forced outages, it assumes that there are the independent and common-cause outage events causing component failures. Then, the objective is to derive the upper and lower bounds on the mean operating time between system failures in the ample-server model. In addtion, the mean system failure times are also considered.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.13-17
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• 2018

According to the recent blackouts, large blackouts can be described by cascading outages. Cascading outage is defined by sequential outages from an initial disturbance. Sequential and probabilistic approach are necessary to minimize the blackout damage caused by cascading outages. In addition, conventional cascading outage analysis models are computationally complex and have time constraints, it is necessary to develop the new analytical techniques. In this paper, we propose the advance visualization model for probabilistic analysis of cascading failure risks. We introduce the visualization model for identifying size of cascading and potential outages and estimate the propagation rate of sequential outage simulation. The proposed model is applied to Korean power systems.

• Journal of Electrical Engineering and Technology
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• v.6 no.4
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• pp.431-438
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• 2011

To ensure that equipment outages do not directly impact the reliability of the ISO-controlled grid, market participants request permission and receive approval for planned outages from the independent system operator (ISO) in competitive electricity markets. In the face of major generation outages, the ISO will make a critical decision as regards the scheduling of the essential maintenance for myriads of generating units over a fixed planning horizon in accordance with security and adequacy assessments. Mainly, we are concerned with a fundamental framework for ISO's maintenance coordination in order to determine precedence of conflicting outages. Simulated annealing, a powerful, general-purpose optimization methodology suitable for real combinatorial search problems, is used. Generally, the ISO will put forward its best effort to adjust individual generator maintenance schedules according to the time preferences of each power generator (GENCO) by taking advantage of several factors such as installed capacity and relative weightings assigned to the GENCOs. Thus, computer testing on a four-GENCO model is conducted to demonstrate the effectiveness of the proposed method and the applicability of the solution scheme to large-scale maintenance scheduling coordination problems.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.6
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• pp.305-311
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• 2000

This paper presents a hybrid algorithm for solving optimal power flow(OPF) in order to enhance a systems capability to cope with outages, which is based on combined application of evolutionary computation and local search method. The efficient algorithm combining main advantages of two methods is as follows : Firstly, evolutionary computation is used to perform global exploitation among a population. This gives a good initial point of conventional method. Then, local methods are used to perform local exploitation. The hybrid approach often outperforms either method operating alone and reduces the total computation time. The objective function of the security constrained OPF is the minimization of generation fuel costs and real power losses. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). In OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The method proposed is applied to IEEE 30 buses system to show its effectiveness.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.429-430
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• 2007

The enlargement of an electric power system network gives us much challenges concerning with network operation. In addition to it, the fast aging process of network equipments requires more chance to check and maintenance, and also the increase of heavy loaded facilities and the increase of the fault current in the network need to exchange with the larger facilities in capacity. Due to these reasons, outages trend to increase. Network solution studies for outages are performed mainly for two purposes. The first one is to find the countermeasures when the outage causes a violation of the network reliability criteria. And the second one is to minimize network constraints due to outages. There are so many outages around 400 for only one month. Therefore, in order to do case studies for outage, not only skilled persons are needed, but also many available tools to help properly. Concerning with proper tools, we will introduce a program which we developed to get informations concerned with network sensitivity, and an example to apply that program.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.9
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• pp.261-272
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• 2021

Rapid economic growth in recent years has caused a surge in energy consumption among Southeast Asian countries and laid a considerable burden on the already inadequate power infrastructure. As a result, frequent blackouts and prolonged outages have become common and weakened firm productive performance in those years. The main objective of this study is to examine the impact of power infrastructure quality on the performance of Southeast Asian manufacturing firms. In this study, the World Bank Enterprise Surveys was employed as the training dataset of 4723 manufacturing firms in the period of 2015-2016. The results of this study reveal that industrial firms that suffered from power outages had consistently lower productivity. As measured by the length of such events, more severe outages tend to be more harmful to the firm. Furthermore, the findings also indicated that most firms relied on self-generated electricity to reduce the negative impact of power outages, but this does not bring many benefits when operating at a small scale in some countries. Consequently, this study contributes to a growing literature that examines the economic impact of public infrastructure and how detrimental the poor state of such services is to a firm's downstream operations, productivity, and growth.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3925-3932
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• 2024

During outages at nuclear power plants, much more care for radiation workers against internal exposure should be ensured given that more hot particles exist relative to the amount during normal operation. If fuel-type hot particles (FTHP) are inhaled, they can cause more severe health risks compared to activation-type hot particles (ATHP), which contain ⁶⁰Co, due to the alpha-emitting nuclides within FTHPs. The activities of difficult-to-measure nuclides within FTHPs inhaled by workers are inferred by the age-dating technique using a¹⁴¹Ce/¹⁴⁴Ce ratio as measured by whole-body counters. However, this method may be limited to outages that last for only a few months due to the short half-life (32.5 days) of ¹⁴¹Ce. We studied the feasibility of utilizing ²⁴¹Am, a nuclide with a long half-life of 432.6 years, as an alternative to ¹⁴¹Ce. Additionally, we improved the performance of a stand-type whole-body counter for low-energy gamma spectroscopy to meet the criterion (RMSE ≤0.25) specified in ANSI/HPS N13.30-2011 by employing an artificial neural network (ANN). This study can contribute to more rapid and accurate internal dose assessments for workers who have inhaled FTHPs during long-term outages at nuclear power plants.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.46-50
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• 2010

Power system outages can lead to huge economic losses for various industries. Jeju island power system outage in 2006 also caused significant social and economic impacts in Korea. There have been numerous attempts to evaluate the economic costs of power system outages. Power system outages can also have financial impacts on electric power industry. This paper attempts to analyze the economic impacts of the 2006 Jeju island power system outage on the values of the firms in the power industry using event study. Empirical analysis results are presented to show the economic impacts of the 2006 Jeju island outage on the values of the firms in the power industry.