• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.290-293
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• 2001

This paper presents the reach accuracy of a distance relay for protection of transmission line according to power system conditions. The apparent impedance of distance relay is considerably affected by source impedance, load current, power factor, fault point and resistance etc. For protective coordination on the variables power system parameters, trip characteristics of distance relay at sending and receiving terminal are discussed.

• 대한전기학회논문지:전력기술부문A
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• 제52권3호
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• pp.143-150
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• 2003

In this paper, we developed the window based monitoring system. This system offers the analysis of accidents in the power plants, the operating status of relays and the historical data with which the experts can offer the idea about the operation of the power system. And we can also monitor the status of the ACB and relay at a long distance by means of the function of communication in the digital protective relay itself. By means of the above functions, we developed the system, which is run after the diagnosis and maintenance of the electrical machines and an amount of data are realized by graphical method fitting the operating convenience of the users.

• 전기학회논문지P
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• 제62권3호
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• pp.151-158
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• 2013

Large generator of power plant is very important. In order to protect large generator from faults, digital protective relay or IED is required. However, all protective relays for generators of the domestic power plant are operated by foreign products. And now, for technological independence from foreign and improvement of import substitution effect, IEDs using domestic technology are being developed. To evaluate performance of developing next-generation power devices, the study of the dynamic characteristics of the power plant, generator system modeling, fault simulation and analysis, should be considered. Specially, To obtain IEEE Standards COMTRADE format for relay operation test, generator system modeling and fault simulation using PSCAD/EMTDC tools must be preceded. Until now, a complete modeling of generator internal windings and fault simulation techniques dose not exist. In this paper, for evaluation performance of relay elements of developing IED, the generator system modeling and various faults simulation using PSCAD/EMTDC tools were performed. And then, the various transient phenomena through obtained relaying signal of developed modeling were analyzed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.215-216
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• 2015

The application of fault current limiter(FCL) reduces power system fault current for circuit breaker to operate properly due to reduced fault current. Also FCL reduces through fault current to the power system equipments. But FCL has changed power system parameters for short time, before application the magnitude of register, triggering current and protective relay coordination have to be studied. In this paper we will examine protective relay coordination with FCL. And propose better solution to assist improving of power system operation through the application of FCL.

• 대한전기학회논문지:전력기술부문A
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• 제49권10호
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• pp.516-523
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• 2000

In this paper, intelligent methods using digital protective relay in power supervisory control system is developed in order to protect power systems by means of timely fault detection and diagnosis during operation for induction motor which has various load environments and capacities in power systems. The spectrum pattern of input currents was used to monitor to state of induction motors, and by clustering the spectrum pattern of input currents, the newly occurrence of spectrums pattern caused by faults were detected. For diagnosis of the fault detected, the fuzzy fault tree was derived, and the fuzzy relation equation representing the relation between an induction motor fault and each fault type, was solved. The solution of the fuzzy relation equation shows the possibility of each fault's occurring. The results obtained are summarized as follows: 1) The test result on the basis of KEMC1120 and IEC60255, show that the operation time error of the digital motor protective relay is improved within ${\pm}5%$. 2) Using clustering algorithm by unsupervisory learning, an on-line fault detection method, not affected by the characteristics of loads and rates, was implemented, and the degree of dependency by experts during fault detection was reduced. 3) With the fuzzy fault tree, fault diagnosis process became systematic and expandable to the whole system, and the diagnosis for sub-systems can be made as an object-oriented module.

• 대한전기학회논문지:전력기술부문A
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• 제52권11호
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• pp.647-654
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• 2003

As electrical power system has become complicated and enlarged to cope with the increasing electric demand, it has to be expected that higher speed, higher reliability, higher function and higher arithmetic ability in protective relay should be realized. Therefore, in this papers, by hardware design and implementation used DMA controller that transfer blocks of data to any location in the memory map without interfering with CPU operation, CPU utilization is increased effectively, as a result it made possible to implement multi-function digital protective relay which has high trust and high function of protection as well as control and metering for power transformers using single processor(DSP).

• 전기학회논문지
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• 제61권6호
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• pp.899-904
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• 2012

In recent years, a lot of research was done for earth fault protection in ungrounded dc power supply system. As a result, selective-breaking integrated protective relaying system is developed in progress and is currently field-testing are planned. Algorithm on a PC using PSCAD done a lot of testing before performing field tests, but in this study developed algorithms and functions needed to determine whether they were operating normally. Therefore, simulated system is similar to the actual situation was required and made. selective-breaking algorithm verification and validation was performed with simulator.

• 한국초전도ㆍ저온공학회논문지
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• 제10권3호
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• pp.9-13
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• 2008

It is very important to study the protective relaying system from the viewpoint of technical analysis to apply superconducting power devices to real power systems. In this paper, we developed Superconducting Fault Current Limiter (SFCL) analysis model using Real Time Digital Simulator(RTDS) for protective relay tests in power system with SFCLs. The RTDS model has the operation mechanism of a real SFCL system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.510-512
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• 2005

This paper introduces the development of automatic system for estimation of digital relay performance. We have developed an automatic estimation system "HRV2004(Himap Relay function Verifier 2004)" for digital relay in 2004 and it has been verified in the field for one years. This paper describes the development details and field experience of HRV2004. HRV2004 can perform a series of jobs required for the relay testing in one environment and could handle most of all models of protective relay currently produced by Hyundai Heavy Industries. The functionality of this program consists of GUI of relay setting for beginner, fault record analysis and relay performance estimation. The core of this system is an automatic reporting of estimation test. If user is only click a button for relay estimation and one will received testing report to deliver customer. Additional benefit is fast response than the manual estimation. For example, the manual estimation takes spending 6 hours but this system is about 15 minutes.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1002-1011
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• 2013

This paper proposes the new adaptive protection algorithm for inverse-time overcurrent relays (OCRs) to ensure their proper operating time and protective coordination. The application of the proposed algorithm requires digital protection relays with microcontroller and memory. The operating parameters of digital OCRs are adjusted based on the available data whenever system conditions (system with distributed generation (DG)) vary. Moreover, it can reduce the calculation time required to determine the operating parameters for achieving its purpose. To verify its effectiveness, several case studies are performed in time-domain simulation. The results show that the proposed adaptive protection algorithm can keep the proper operating time and provide the protective coordination time interval with fast response.