• Title, Summary, Keyword: Outage minimization

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An Application of advanced Dijkstra algorithm and Fuzzy rule to search a restoration topology in Distribution Systems (배전계통 사고복구 구성탐색을 위한 개선된 다익스트라 알고리즘과 퍼지규칙의 적용)

  • Kim, Hoon;Jeon, Young-Jae;Kim, Jae-Chul;Choi, Do-Hyuk;Chung, Yong-Chul;Choo, Dong-Wook
    • Proceedings of the KIEE Conference
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    • pp.537-540
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    • 2000
  • The Distribution System consist of many tie-line switches and sectionalizing switches, operated a radial type. When an outage occurs in Distribution System, outage areas are isolated by system switches, has to restored as soon as possible. At this time, system operator have to get a information about network topology for service restoration of outage areas. Therefore, the searching result of restorative topology has to fast computation time and reliable result topology for to restore a electric service to outage areas, equal to optimal switching operation problem. So, the problem can be defined as combinatorial optimization problem. The service restoration problem is so important problem which have outage area minimization, outage loss minimization. Many researcher is applying to the service restoration problem with various techniques. In this paper, advanced Dijkstra algorithm is applied to searching a restoration topology, is so efficient to searching a shortest path in graph type network. Additionally, fuzzy rules and operator are applied to overcome a fuzziness of correlation with input data. The present technique has superior results which are fast computation time and searching results than previous researches, demonstrated by example distribution model system which has 3 feeders, 26 buses. For a application capability to real distribution system, additionally demonstrated by real distribution system of KEPCO(Korea Electric Power Corporation) which has 8 feeders and 140 buses.

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Hybrid Diversity-Beamforming Technique for Outage Probability Minimization in Spatially Correlated Channels

  • Kwon, Ho-Joong;Lee, Byeong-Gi
    • Journal of Communications and Networks
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    • v.9 no.3
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    • pp.274-281
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    • 2007
  • In this paper, we present a hybrid multi-antenna technique that can minimize the outage probability by combining the diversity and beamforming techniques. The hybrid technique clusters the transmission antennas into multiple groups and exploit diversity among different groups and beamforming within each group. We analyze the performance of the resulting hybrid technique for an arbitrary correlation among the transmission antennas. Through the performance analysis, we derive a closed-form expression of the outage probability for the hybrid technique. This enables to optimize the antenna grouping for the given spatial correlation. We show through numerical results that the hybrid technique can balance the trade-offs between diversity and beamforming according to the spatial correlation and that the optimally designed hybrid technique yields a much lower outage probability than the diversity or beamforming technique does in partially correlated fading channels.

User Scheduling Algorithm Based on Signal Quality and Inter-User Interference for Outage Minimization in Full-Duplex Cellular Networks (전이중 셀룰라 네트워크에서 아웃티지 최소화를 위한 신호 품질과 사용자간 간섭량 기반의 사용자 스케쥴링 알고리즘)

  • Choi, Hyun-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.11
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    • pp.2576-2583
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    • 2015
  • In a full-duplex (FD) wireless cellular network, uplink (UL) users induce the severe inter-user interference to downlink (DL) users. Therefore, a user scheduling that makes a pair of DL user and UL user to use the same radio resource simultaneously influences the system performances significantly. In this paper, we first formulate an optimization problem for user scheduling to minimize the occurrence of outage, aiming to guarantee the quality of service of users, and then we propose a suboptimal user scheduling algorithm with low complexity. The proposed scheduling algorithm is designed in a way where the DL user with a worse signal quality has a higher priority to choose its UL user that causes less interference. Simulation results show that the FD system using the proposed user scheduling algorithm achieves the optimal performance and significantly decreases the outage probability compared with the conventional half-duplex cellular system.

Establishment of cryogenic propellant loading mass and estimation of residual propellant mass (액체로켓 추진기관에서의 극저온 추진제 탑재량 및 잔류량 예측기법)

  • Cho Nam-Kyung;Han Sang-Yeop;Kim Young-Mog
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.191-195
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    • 2005
  • Propellant remains as outage at engine shutdown contributes no useful impulse to the rocket and produces an unwanted increase in burnout weight. Minimization of outage, is therfore is a basic consideration in attaining the maximum performance capability of my bipropellant liquid rocket. This paper present the calculation procedures of outage and optimum loading propellant mass. And some control methods and measurement techniques for outage are presented.

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Development of Feeder Automation Software Considering the Diversity Events of Distribution Systems (배전계통의 다양한 이벤트들을 고려한 선로자동화 소프트웨어 개발)

  • 고윤석
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.8
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    • pp.463-470
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    • 2003
  • This paper proposes an expert system, which is able to determine the problem-solving strategy for diversity events occurred on the distribution system. The events include events related to the fault, scheduled outage and optimal operating task such as feeder line fault, line scheduled outage, line overload, system load balancing, system loss minimization, main transformer fault, main transformer scheduled outage, main transformer overload, main transformer protection control. The expert system enhances the reliability of software designed by the integrated concept for the diversity events. The expert system is implemented in C language. And the effectiveness and accuracy for the expert system is verified by simulating the event cases for typical distribution model.

Development of Feeder Automation Software Considering the Diversity Events of Distribution System (배전계통의 다양한 이벤트들을 고려한 선로자동화 소프트웨어 개발)

  • Ko, Yun-Seok;Kim, Yun-Jib;Bak, Young-Gu;Lee, Kee-Seo
    • Proceedings of the KIEE Conference
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    • pp.307-309
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    • 2002
  • This paper proposes an expert system, which is able to determine the problem-solving strategy for diversity events occurred on the distribution system. The events include events related to the fault, scheduled outage and optimal operating task such as feeder line fault, line scheduled outage, line overload, system load balancing, system loss minimization, main transformer fault, main transformer scheduled outage, main transformer overload, main transformer protection control. The expert system enhances the reliability of software designed by the integrated concept for the diversity events.

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Energy-efficient Buffer-aided Optimal Relay Selection Scheme with Power Adaptation and Inter-relay Interference Cancellation

  • Xu, Xiaorong;Li, Liang;Yao, Yingbiao;Jiang, Xianyang;Hu, Sanqing
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.11
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    • pp.5343-5364
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    • 2016
  • Considering the tradeoff between energy consumption and outage behavior in buffer-aided relay selection, a novel energy-efficient buffer-aided optimal relay selection scheme with power adaptation and Inter-Relay Interference (IRI) cancellation is proposed. In the proposed scheme, energy consumption minimization is the objective with the consideration of relay buffer state, outage probability and relay power control, in order to eliminate IRI. The proposed scheme selects a pair of optimal relays from multiple candidate relays, denoted as optimal receive relay and optimal transmit relay respectively. Source-relay and relay-destination communications can be performed within a time-slot, which performs as Full-Duplex (FD) relaying. Markov chain model is applied to analyze the evolution of relay buffer states. System steady state outage probability and achievable diversity order are derived respectively. In addition, packet transmission delay and power reduction performance are investigated with a specific analysis. Numerical results show that the proposed scheme outperforms other relay selection schemes in terms of outage behavior with power adaptation and IRI cancellation in the same relay number and buffer size scenario. Compared with Buffer State relay selection method, the proposed scheme reduces transmission delay significantly with the same amount of relays. Average transmit power reduction can be implemented to relays with the increasing of relay number and buffer size, which realizes the tradeoff between energy-efficiency, outage behavior and delay performance in green cooperative communications.

Minimum Transmit Power Strategy for Poisson Distributed Wireless Ad-hoc Relay Networks in Rayleigh Fading Channels (레일리 페이딩 채널 환경에서 포아손 분포된 무선 Ad-hoc 릴레이 네트워크를 위한 최소 전송 전력 전략)

  • Kim, Nam-Soo;An, Beongku;Kim, Do-Hyeon;Lee, Ye Hoon
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.8 no.3
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    • pp.25-33
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    • 2008
  • In this paper, the transmit power minimization for Poisson distributed wireless ad-hoc relay networks in Rayleigh fading channels is considered. We investigate two power allocation methods one is a minimum power allocation (MPA) strategy and the other is an equal outage power allocation (EOPA) strategy. We analyze the total transmit power of two allocation methods under the given end-to-end outage probability constraint. Our results show that the MPA achieves more power saving than EOPA, and the power saving is more significant as the number of relay nodes increases.

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Outage Optimal Transmission Strategy for Full-Duplex Relay System (전이중 릴레이 시스템에서 오수신 확률을 최소화 시키는 전송 기법)

  • Lee, Sun-Young;Kim, Seong-Lyun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.11A
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    • pp.853-860
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    • 2011
  • In this paper, we proposed a transmission scheme for a full-duplex relay system that minimizes outage probability. A relay system with the full-duplex relay can mitigate resource inefficiency of a half-duplex relay system. However, the mobile station suffers from the interference because the base station and the relay station transmits signal simultaneously to the mobile station. First, we suggest a layered broadcasting for full-duplex relaying. Second, we derive an optimal power allocation for the layered broadcasting in terms of the outage probability minimization. The proposed algorithm shows better performance than a half-duplex relaying system with and without the diversity, and a conventional full-duplex relaying system.

Protection for a Wind Turbine Generator in a Large Wind Farm

  • Zheng, Tai-Ying;Kim, Yeon-Hee;Kang, Yong-Cheol
    • Journal of Electrical Engineering and Technology
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    • v.6 no.4
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    • pp.466-473
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    • 2011
  • This paper proposes a protection algorithm for a wind turbine generator (WTG) in a large wind farm. To minimize the outage section, a protection relay for a WTG should operate instantaneously for an internal fault or a connected feeder fault, whereas the relay should not operate for an internal fault of another WTG connected to the same feeder or an adjacent feeder fault. In addition, the relay should operate with a delay for an inter-tie fault or a grid fault. An internal fault of another WTG connected to the same feeder or an adjacent feeder fault, where the relay should not operate, is determined based on the magnitude of the positive sequence current. To differentiate an internal fault or a connected feeder fault from an inter-tie fault or a grid fault, the phase angle of the negative sequence current is used to distinguish a fault type. The magnitude of the positive sequence current is then used to decide either instantaneous operation or delayed operation. The performance of the proposed algorithm is verified under various fault conditions with EMTP-RV generated data. The results indicate that the algorithm can successfully distinguish instantaneous operation, delayed operation, or non-operation depending on fault positions and types.