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반주기 슬라이딩 윈도우와 재귀적 실효치 계산을 이용한 국내 플리커 평가지수 산출기법
조수환(Soo-Hwan Cho) 대한전기학회 2011 전기학회논문지 Vol.60 No.11
Flicker, which is also known as voltage fluctuation, is an electromagnetic phenomenon generated by large scale nonlinear loads, such as arc furnaces and welding machines. Since a severe and continuous flicker can cause to some damages to electrically sensitive loads as well as human"s visual irritations, it needs to be appropriately managed by being accurately measured, quantified and assessed. In Korea, an equivalent 10-Hz flicker index, shortly ΔV<sub>10</sub>, is used to determine the permission limit of flicker. This paper presents an efficient calculation of the flicker index by using a half-cycle sliding window and a recursive method, showing a concrete calculating procedure of ΔV<sub>10</sub> from the viewpoint of signal processing.
IEC 국제표준에 따른 계통연계형 풍력터빈 발전기계통의 전력품질 측정방법에 관한 심화연구
조수환(Soo-Hwan Cho) 대한전기학회 2014 전기학회논문지 Vol.63 No.2
As more and more renewable energy resources are connected into the existing power system and their generation capacities are increasing, the need for regulations to minimize their impacts on the power grid is increasingly growing. And minimizing the irregular impacts made by grid-connected wind generators is important, since the output power generated by renewable energy resources can be changed easily by the weather condition and surrounding environment. In South Korea, an operational technical standard for distributed generation is used as a regulation, in which renewable energy sources including wind power are considered as a kind of distributed generation. In this paper, an international standard, IEC 61400-21, for the grid-connected wind turbine generating system(WTGS) will be introduced and a comprehensive and detailed review on the measuring methods of power quality characteristic parameters for WTGS based on the related IEC standards will be presented. Additionally, some prerequisites for applying the international standards to KEPCO system will be proposed.
조수환(Soo-Hwan Cho),장길수(Gilsoo Jang),권세혁(Sae-Hyuk Kwon),박상호(Sang-Ho Park),전영수(Young-Soo Jeon),곽노홍(No-Hong Kwak) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
The installations of power quality monitoring system have increased drastically over the past several decades. These systems have been effectively used to monitor, analyze and diagnose the conditions of power system, and furthermore can be used to improve the present asset maintenance policy, scheduled (time-based) method, into the advanced, cost-effective and labor-effective maintenance methods, such as condition-based maintenance, predictive maintenance and reliability centered maintenance. As an approach to this, this paper introduces the statistical methods, three kinds of control charts (Shewhart chart, CUSUM chart and EWMA chart), and discusses the applicability of these methods to recognize the changing trends of power quality indices and to estimate the system's condition, using Matlab.
조수환(Soo-Hwan Cho),장길수(Gilsoo Jang),권세혁(Sae-Hyuk Kwon),전영수(Young-Soo Jeon) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.11
Predictive maintenance is not an unfamiliar concept because it has been used to predict the failures of electrical equipment such as transformers, motors and so on. By thoroughly monitoring the status of individual equipment and tracing how the various characteristics change over time, we can be aware of its exact condition and prevent the impending failure by taking appropriate actions. In this paper, I will extend the concept of predictive maintenance for individual electrical equipment to the power distribution system and show how to use the data obtained from power quality monitors to improve the power system.
조수환(Soo-Hwan Cho),김형규(Hyung-Kyoo Kim) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
HANARO, High-flux Advanced Neutron Application ReactOr, is the only nuclear research reactor of Korea, whose thermal power is 30㎿, corresponding to 10㎿ electric power. It is not too much to say that many recent academic and industrial achievements related to neutron applications are realized by HANARO. It is of great importance in Korean scientific communities. However, the HANARO complex is a large scale load in electric distribution system, which consumes the electric power of about 2㎿, periodically repeating its operation and shut-down. This paper analyzes the harmonic distortion effected by the operation status of HANARO. It is expected to give an important data for the current safety analysis.
1-cycle RMS를 이용한 독립계통용 디젤발전기의 자동전압제어장치 성능 개선에 관한 연구
유준수(Joon-Soo Lyu),배민식(Min-Sik Bae),조수환(Soo-Hwan Cho) 한국조명·전기설비학회 2021 조명·전기설비학회논문지 Vol.35 No.1
Since the power system in an island area is generally small-scale and not connected to the main land, it should be able to operate independently. And the power is mainly supplied by diesel generators. Under these circumstances, the frequency variation occurs easily when a variable load with a large capacity is operated during the diesel generator start-up or stand-alone operation. So, AVR(Automatic Voltage Regulator) unit generally used in the main land, which is based on 60 Hz fundamental frequency DFT(Discrete Fourier Transform) algorithm, cannot control the voltage reliably and immediately due to the error of voltage effective value caused by the system frequency fluctuation. In this study, the performance of the AVR unit with 1-cycle RMS(Root Mean Square) algorithm, which enables stable voltage control despite frequency variation, was developed and demonstrated through field application tests.
교육용 스마트 발전, 송전 및 배전 실험장치에 관한 연구
최태환(Tae-Hwan Choi),배진용(Jin-Yong Bae),조수환(Soo-Hwan Cho) 대한전기학회 2018 대한전기학회 학술대회 논문집 Vol.2018 No.-
This paper presents the smart power generation transmission and distribution experiment equipment for education. The proposed experimental system is used to test the power generation in renewable energy generation, AC or DC generation, and nuclear power generation, transmission and distribution experiments to collectively transmit AC power and conduct HVDC(High Voltage DC) transmission and AC load(AC motor, Lamp) and DC load (DC motor, LED).