• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1038-1040
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• 1997

This paper describes dynamic characteristics test of distance relay and current differential relay using Real Time Digital Simulator on double circuit transmission line. First, The double circuit T/L modeling on RTDS was proposed and the results from the proposed model were compared with those of PSS/E. This comparison shows the possibility of dynamic test using the RTDS. The relay included about 20 test items which are apt to include maloperation of protective relays in critical situations.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 춘계학술대회
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• pp.77-78
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• 2022

현재 해상에서의 통신은 파도로 인한 항로표지의 움직임에 의해 내륙에서의 통신과 비교했을때 어려움이 있다. 본 논문에서는 uplink 상황에서 커버리지 확장을 위한 relay 송수신 기법연구를 진행한다. 내륙에 위치한 기지국과 내륙으로부터 일정 거리 떨어진 해상에 위치한 부표들 간의 uplink 해상통신 환경을 two-hop으로 고려하였으며, 센서로 측정한 파도로 인한 부표의 움직임을 고려하여 안테나 개수에 따라 만들어진 빔을 선택하고 성능 분석을 진행한다.

• 전기학회논문지
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• 제61권10호
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• pp.1542-1547
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• 2012

Asynchronous phenomenon occurs on the synchronous generators under power system when a generator's amplitude of electromagnetic force, phase angle, frequency and waveform etc become different from those of other synchronous generators which can follow instantly varying speed of turbine. Because the amplitude of electromagnetic force, phase frequency and waveform differ from those of other generators with which are to be put into parallel operation due to the change of excitation condition for load sharing and the sharing load change, if reactive current in the internal circuit circulates among generators, the efficiency varies and the stator winding of generators are overheated by resistance loss. When calculation method of protection settings and logic for protection of generator asynchronization will be recommended, a distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome asynchronizing protection, this paper describes an improved backup protection coordination scheme using a new logic that will be suggested.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.377-378
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• 2008

한전에서는 계통보호 설비의 신뢰도 확보를 위해 디지털 보호설비 사용을 확대하고 있으며, 이에 따른 합리적인 보호설비 교체기준을 설정하려고 한다. 본 논문에서는 디지털 보호계전기의 교체기준 설정을 위해 디지털 보호 계전기(Digital Distance Relay)와 구성모듈에 대한 고장률(Failure rate)과 평균수명(Mean Time between Failures, MTBF), 그리고 시간에 따른 신뢰도를 분석하였다. 수명예측방법은 MIL-HDBK-217F, Notice 2의 부품스트레스분석방법(Part Stress Analysis Method) 사용하였다.

• 전기학회논문지
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• 제56권2호
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• pp.240-247
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• 2007

This paper presents an implementation of the generator protective relay using Real Time Digital Simulator (RTDS) user defined component (UDC) model designed to facilitate the investigation and evaluation of protective relays. The UDC for RTDS is a convenient model that allows user to develop new component models and run them on the RTDS. The developed model has major features related to the development of six models such as distance, frequency, reverse power, volts per Hz, over voltage, and out-of-step relays. Also, the generator relay models have been used to support and enhance power engineering education at both the undergraduate and graduate levels. The developed model functions are verified and tested by both static test and dynamic test. The simulation results show the capabilities of the developed generator relay using RTDS UDC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.102-122
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• 2017

Nanotechnology has provided a set of tools that the engineers can use to design and manufacture integrated nano devices, which are capable of performing sensing, computing, data storing and actuation. One of the main hurdles for nano devices has been the amount of power that it can generate for transmission of data. In this paper, we proposed cooperative nano communication in the Terahertz (THz) Gap frequency band to increase the range of transmission. Outage probability (OP) performances for the proposed cooperative nano communication networks in the THz band (0.1 - 10THz) have been evaluated for the following scenarios; A) A single decode-and-forward (DF) relay over independent identically distributed (i.i.d.) Rayleigh fading channels, B) DF multi-relay network with best relay selection (BRS) over i.i.d. Rayleigh fading channels, and C) DF multi-relay network with multiple hops with BRS over i.i.d. Rayleigh fading channels. The results show that the transmission distance can be improved significantly by employing DF relays. Also, it is shown that by increasing the number of hops in a relay the OP performance is marginally degraded. The analytical results have been verified by Monte-Carlo simulation.

• 조명전기설비학회논문지
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• 제28권1호
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• pp.69-78
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• 2014

In this paper, characteristics of wireless power transfer (WPT) systems using magnetically coupled resonance scheme with relay coils are investigated and modeled. Especially, asymmetric frequency splitting characteristics in over-coupled region of WPT with relays are measured and accurately modeled. Transmitter, receiver, and relay coils are modeled with R, L, C equivalent circuits. Using these circuit models and mutual inductances between coils, a WPT system is described with a linear matrix equation. For under-coupled region, a matrix is simplified considering only mutual inductances between adjacent coils. An analytical transfer characteristic of WPT system vs. distance is extracted using an inverse matrix that is acquired by Gauss elimination method for the simplified matrix. For over-coupled region, a matrix considering mutual inductances between non-adjacent coils is used to predict a frequency splitting characteristics accurately. A 6.3MHz WPT system with relay coils is implemented and measured. An accuracy of the model is investigated by comparing the output of the model with the measured results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권10호
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• pp.2732-2749
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• 2023

Device-to-Device (D2D) communication has received increasing attention and been studied extensively thanks to its advantages in improving spectral efficiency and energy efficiency of cellular networks. This paper proposes a novel relay selection algorithm for multi-hop full-duplex D2D communications underlaying cellular networks. By selecting the relay of each hop in a reverse manner, the proposed algorithm reduces the heavy signaling overhead that traditional relay selection algorithms introduce. In addition, the social domain information of mobile terminals is taken into consideration and its influence on the performance of D2D communications studied, which is found significant enough not to be overlooked. Moreover, simulations show that the proposed algorithm, in absence of social relationship information, improves data throughput by around 70% and 7% and energy efficiency by 64% and 6%, compared with two benchmark algorithms, when D2D distance is 260 meters. In a more practical implementation considering social relationship information, although the proposed algorithm naturally achieves less throughput, it substantially increases the energy efficiency than the benchmarks.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.175-177
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• 2008

본 논문에서는 I-PIU를 통해 등기화된 데이터를 취득 이용하여 실시간 계통 감시는 물론 광역정전방지에 대한 방법을 제안하고 있다. 또한 민감도 지수(Sensitivity Factor)를 이용한 취약도 지수(Vulnerability Index)와 실시간 데이터를 이용한 거리계전기 동작을 예측 알고리즘을 적용하여 실시간 계통의 상황감시는 물론 계통의 위험 정도를 미리 알리는 거리 계전기 모니터링 시스템을 설계하였다 이는 운영자로 하여금 개통의 위험 요소를 적절한 조치를 취해 제거함으로써 치명적인 광역 정전 사태의 방지와 효율적 계통관리를 기대 할 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.333_335
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• 2009

It is expected, in the near future, that the use of distributed generation systems should be increased considerably. In this case, distance relay algorithm should be developed in the manner that it can reduce the error due to the in-feed effect. This paper presents a method to consider the fault current rushed from the remote end of a line. In the steady-state, the relays in both ends exchange the voltages of upper nodes. If a fault is perceived, the relay calculates fault location taking the fault current from the remote end by using voltage data of the remote ends obtained just before the fault. Even though this method has inevitable error, it can show more precise fault allocation. The suggested method is applied to a typical transmission system with two power sources in both ends to verify its effectiveness.