• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.97-107
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• 2010

Penetration of distributed generator(DG) to power distribution system can cause malfunction of existing protection schemes. Because grid interconnected DG can contribute fault currents and make bidirectional current flows on the system, fault contributions from DG can cause an interference of protection relay operation. Therefore, over current protection device of the distribution system with DGs need directional protection schemes. In this paper, improved directional protection algorithms are proposed for the distribution system with DG considering their fault characteristics. And than, these directional protection algorithms are tested and validated in various fault conditions. From the simulation results, it can be seen that the proposed directional protection algorithms are practically efficient for the radial distribution system with DG.

• Fire Science and Engineering
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• v.26 no.6
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• pp.38-44
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• 2012

The purpose of fire protection for the nuclear power plants (NPPs) is to ensure safe shutdown state of the reactor, to minimize the release of radioactive materials to the environment, to provide physical safety of the on-site personnel, and to limit the property damage. Fire protection and extinguishing equipments are one of the important protection measures based on the defense-in-depth concept, which can promptly detect and control and extinguish those fires that do occur, thereby limiting fire damage. However, a separate evaluation process might be additionally necessary for the construction permit and operating license because the fire protection laws of the NEMA for installation standards of the fire protection systems is not fully characterized for the NPPs. It is also not easy to implement the regulations such as the performance based design concept for fire protection system of the NPPs which are characterized for a relatively low density of employee. This study suggests a guideline for the improvement of the technical standards for fire protection systems of the NPPs by evaluating the fundamental problems drawn by reviewing laws and regulatory guides relevant to fire protection and by evaluating the applicability of the KEPIC FPN in domestic nuclear power plants.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.4
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• pp.667-674
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• 2004

This thesis is about the Impressed Current Cathodic Protection (ICCP) control and monitoring system. which brings protection against the corrosion of the ship's hull in the sea environments. The ICCP system is composed of a power supply. anode. reference electrode and controller. AC sources from the ship's generator are converted to DC sources in terms of power supply, and a protection current is sent to ship's hull though anode. The controller fully senses whether or not the detected potential is within a range of protection of ship's hull and then it is automatically controlled to increase or decrease the amount of protective current to be sent to the anode. The monitoring system with RS 232/485 communication is also studied in order to check the normal state of the system at a long period. because an operator does not always watch over this system and thus the system cannot operate well because of his or her negligent management. Since the vessel always navigates in the sea. an characteristics experiment of the ICCP system is conducted by introducing various corrosive environmental factors such as velocity, resistivity, dissolved oxygen, PH, temperature and contamination degree. These results must be referred to when the ICCP system is set up. In short. the ICCP is a multi-system for use on ships and on land structures because it includes a safety device. It is suggested that this system can accomodate a ship's automation and will be very useful.

• Journal of Electrical Engineering and information Science
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• v.1 no.2
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• pp.52-57
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• 1996

Detection of arcing high impedance faults has been a perplexing in the power distribution protection. Transient analysis of distribution disturbances for fault discrimination from other normal events is important for a secure protection of the power system. A simple parameter of wave form distortion quantification is used to analyze the behaviors of arcing faults and normal distribution disturbances. Theoretical perspectives of the transients were studied and actual disturbances were examined. From this investigation, a discrimination guideline based on the revised crest factor is developed. The discrimination method has a high potential to enhance the reliability and security for the distribution system protection.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.3
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• pp.25-38
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• 2023

Instrumentation and control systems measure and control various variables of nuclear facilities to operate nuclear power plants safely. A diverse protection system, a representative instrumentation and control system, generates a reactor trip and turbine trip signal by high pressure in a pressurizer and containment to satisfy the design requirements 10CFR50.62. Also, it generates an auxiliary feedwater actuation signal by low water levels in steam generators. Cybersecurity has become more critical as digital technology is gradually applied to solve problems such as performance degradation due to aging of analog equipment, increased maintenance costs, and product discontinuation. This paper analyzed possible cybersecurity threat scenarios in the diverse protection system using attack trees. Based on the analyzed cybersecurity threat scenario, we calculated the probability of attack occurrence and confirmed the cybersecurity risk in connection with the asset value.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1074-1077
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• 1993

The objective of this paper is to develop a fuzzy logic based decision-making system to detect low current faults using multiple detection algorithms. This fuzzy system utilizes a fuzzy expert model which executes an operation without complicated mathematical models. This fuzzy system decides the performance weights of the detection algorithms. The weights and the turnouts of the detection algorithms discriminate faults from normal events. This system can also be a generic group decision-making tool for other areas of power system protection.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.193-195
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• 2002

This paper presents the methods to solve the problem about Power System Protection Program(PROSET) and describe the database relation and schema with UML. PROSET is a overall program system to protect power system and correct it. In the context of the PROSET it is so difficult to edit database data when topology is changed. When the renewal of data is performed. all changed values are disappeared. Therefore, it will not be expected to know the present situation by using the information of the databases data. So it is necessary to solve this problem. Solution is copy of the user. Only E.R diagram is used to express database schema and relation. So, in this paper, UML(Unified Modeling Language) will be used to express PROSET and database of MCD-H and MDT-H.

• Nuclear Engineering and Technology
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• v.34 no.3
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• pp.259-267
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• 2002

NFPA-803 has been referred as the Fire Protection Standard at the Nuclear Power Plants of Pressurized Water Reactor. This Standard has been used as the fire protection regulation, containing prescriptive requirements with deterministic methodology. Recently, with cumulative efforts by the U.S. Nuclear Regulatory Commission and Utilities in America to establish a new Standard, including a quantitative evaluation methodology, NFPA-805, the Performance-Based Standard for FIRE Protection for Light Water Reactor Electric Generating Plants was issued and approved by the American National Standards Institute as an American National Standard with an effective date of February 9, 2001. This paper presents an analysis result from the computer modeling for the fire simulation In addition, it proposes the idea that this kind of analytic method can be available for the facilities design of fire prevention and protection fields, as well as an evaluation for the fire suppression system with a quantitative analysis for the thermal phenomena in fire compartments in Nuclear Power Plants.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.348-350
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• 2003

In recent years, with the continuous development of modem power system, the need for high performance protection to meet the customers' requests for more stable and reliable power supply has become increasingly emphasized. So, there is urgent need for a proper testing platform about not only existing digital protection relay but also new digital protection relay on the transmission line. It is also dynamic-state test which can test the performance of digital relay. This paper suggests basic system model for testing transmission line protection using PSCAD/EMTDC, and presents the process of the component modeling in the basic system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.445-450
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• 2014

Jeju power system is connected to the mainland power system through HVDC, and receives about half of required electricity through the HVDC lines. Jeju power system already experienced black out when a generator tripped at the moment of the HVDC line faults. But, UFR operated as was expected when HVDC line fault occurred at that time. As the penetration level of wind turbines increases, it is required to set UFR again considering intermittent wind turbin outputs. In this paper, we address a new way of UFR setting through computer simulation.