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오윤식(Yun-Sik Oh),이정훈(Jung-Hoon Lee),신승민(Seung-Min Shin),고정민(Jeong-Min Ko),이병국(Byoung-Kuk Lee) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.10
본 논문에서는 필터 비용 증가와 시스템의 동특성을 파악 하기위해 대표적인 low-pass-filter인 LC 필터와 LCL 필터를 자세히 설계하고 두 경우를 비교 분석 하였으며 이를 시뮬레이션을 통해 확인하였다.
오윤식(Yun-Sik Oh),권기현(Gi-Hyeon Gwon),박지경(Ji-Kyung Park),조규정(Kyu-Jung Jo),손승현(Seung-Hyun Sohn),김철환(Chul-Hwan Kim),김완종(Wan-Jong Kim) 대한전기학회 2013 전기학회논문지 Vol.62 No.6
Most of faults occurring in transmission lines are transient faults. For such faults, automatic reclosing is economic and effective method to improve the reliability and transient stability of power system. Many countries apply various reclosing schemes considering issues of their own systems such as transient stability, rate of success. Currently, different reclosing schemes are applied in Korean transmission systems according to a rated voltage. In this paper, we conduct an evaluation of reclosing schemes in Korean transmission systems considering transient stability. Computer simulations are performed by using ElectroMagnetic Transient Program (EMTP) and transmission system is modeled based on actual data of Korea.
배전계통 정전복구 연구를 위한 연동 시뮬레이션 환경 구축
오윤식(Yun-Sik Oh) 한국조명·전기설비학회 2022 조명·전기설비학회논문지 Vol.36 No.6
Faults of components on distribution networks result in electricity interruptions for all loads downstream of a faulty zone since distribution networks have been generally operated in radial structures due to simple design, low cost, and simple protection coordination. To restore the outage loads in the healthy areas, service restoration should be taken by using normally open switches to transfer the loads to other feeders. This paper proposes a co-simulation environment for service restoration studies composed of sub-simulation tools, OpenDSS and MATLAB, which enables distribution network modeling, power flow analysis, constraints check, generating service restoration candidates, etc. Multiple case studies on IEEE 37-node system are conducted under the proposed simulation environment in order to verify its performance and it is shown that the proposed environment is effective for the service restoration studies.
오윤식(Yun-Sik Oh),강성범(Sung-Bum Kang),서훈철(Hun-Chul Seo),김철환(Chul-Hwan Kim) 대한전기학회 2012 전기학회논문지 Vol.61 No.7
Most of faults occurred in transmission lines are single-phase to ground faults and transient faults. Single-phase auto reclosing is an appropriate scheme to maintain the system stability and restore the system effectively when those faults are occurred. In single-phase auto reclosing scheme, the secondary arc is generated after faulted phase is tripped to eliminate the fault and it is sustained by the capacitive and inductive coupling to the healthy phases. It is important to reclose the faulted phase after fully extinction of secondary arc because of the damage applied to system. Therefore, it is necessary to research on the detection of secondary arc extinction to ensure high success rate of reclosing. In this step, firstly, the accurate modelling of secondary arc should be performed. In this paper, the modelling of secondary arc is performed by using EMTP-RV and the simulation results show that the implemented model is correct and effective.
수학적 형태학 기반의 필터를 이용한 저압직류 배전계통의 고저항 지락고장 검출에 관한 연구
오윤식(Yun-Sik Oh),노철호(Chul-Ho Noh),김두웅(Doo-Ung Kim),권기현(Gi-Hyeon Gwon),한준(Joon Han),김철환(Chul-Hwan Kim) 한국조명·전기설비학회 2015 조명·전기설비학회논문지 Vol.29 No.11
As a solution of improving the energy efficiency in power system, Low Voltage DC (LVDC) distribution systems different from conventional ones have been constantly researched. As in conventional AC distribution system, LVDC distribution system can suffer from High Impedance Fault (HIF) which may cause a failure of protective relay due to relatively low change in magnitude of fault current. In order to solve the problem, a scheme for detecting HIFs is presented in this paper. Closing Opening Difference Operation (CODO) based on Mathematical Morphology (MM), one of the MM-based filters, is utilized to make fault signals discriminable. To verify performance of the scheme, a simple LVDC distribution system is modeled by using ElectroMagnetic Transient Program (EMTP) software. Computer simulations according to various conditions are performed and comparison studies with a scheme using Wavelet Transform (WT) in an aspect of simulation time are also conducted.
제어 가능한 전류원 기반의 인버터를 이용한 실제적 태양광 발전 시스템 모델링
오윤식(Yun-Sik Oh),조규정(Kyu-Jung Cho),김민성(Min-Sung Kim),김지수(Ji-Soo Kim),강성범(Sung-Bum Kang),김철환(Chul-Hwan Kim),이유진(You-Jin Lee),고윤태(Yun-Tae Ko) 대한전기학회 2016 전기학회논문지 Vol.65 No.8
Utilization of Distributed Generations (DGs) using Renewable Energy Sources (RESs) has been constantly increasing as they provide a lot of environmental, economic merits. In spite of these merits, some problems with respect to voltage profile, protection and its coordination system due to reverse power flow could happen. In order to analyze and solve the problems, accurate modeling of DG systems should be preceded as a fundamental research task. In this paper, we present a PhotoVoltaic (PV) generation system which consists of practical PV cells with series and parallel resistor and an inverter for interconnection with a main distribution system. The inverter is based on controllable current source which is capable of controlling power factors, active and reactive powers within a certain limit related to amount of PV generation. To verify performance of the model, a distribution system based on actual data is modeled by using ElectroMagnetic Transient Program (EMTP) software. Computer simulations according to various conditions are also performed and it is shown from simulation results that the model presented is very effective to study DG-related researches.
협조 제어를 이용한 분산전원 연계 배전계통의 전압조정 방식 개발
오윤식(Yun-Sik Oh),조규정(Kyu-Jung Cho),김민성(Min-Sung Kim),김지수(Ji-Soo Kim),김철환(Chul-Hwan Kim) 대한전기학회 2017 전기학회논문지 Vol.66 No.9
As penetration level of Distributed Generations (DGs) on weak distribution networks gets higher, voltage rise problem can often occur due to reverse power which is not expected in conventional distribution networks. It, however, cannot be effectively solved by using conventional voltage regulating devices such as On-Load Tap Changers (OLTCs), Step Voltage Regulators (SVRs) because those do not consider the presence of DGs when determining relevant setting parameter for voltage regulation. This paper presents a scheme for voltage regulation using coordinated control between OLTC and DGs which can actively participate in the regulation. The scheme decides which device should be operated first based on the characteristics of regulating devices, in order to prevent unnecessary operation of output changes of DG and excessive tap changing operation of OLTC. Computer simulations considering daily irradiation of PV and load curve are performed by using MATLAB Simulink and performance comparison between the presented scheme and conventional ones is also made. It can be concluded from simulation results that the scheme presented is very effective to regulate voltages in distribution networks with multiple DGs.