상호상관 함수를 이용한 지중선로 고장점 추정

朴星完,林泳範,鄭州桓,成洛煥,金喆煥,申明徹 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2

This paper is intended as an investigation of fault location for underground line. Over the past few decades a considerable number of studies have been made on protection of underground line. However, these approaches require the interruption of electric power supply from source for fault location estimation. Therefore, we proposed fault location algorithm for underground line protection without interruption of electric power supply. Cross correlation function is used in this algorithm. Also, EMTP data is used to demonstrate the capability of the proposed fault location algorithm.

진행파를 이용한 디지탈 거리 계전기법의 고장발생각에 따른 고장거리 산출 보정에 관한 연구

정주환,서희석,김철환,신명철 成均館大學校 科學技術硏究所 1992 論文集 Vol.43 No.1

For many years digital protective methods have employed for the calculation of transient phenomena on power system networks caused by faults. This paper presents a travelling wave digital protection scheme to be used as an ultra high speed EHV/UHV transmission line relay. A detection of fault is made by a highly reliable relaying algorithm which makes use of the modal components of the voltage and currents which are caused to be superimposed on the steady state prefault power frequency components following the fault inception. Some of the potential problems and limitations associated with fault angles are achieved using correction factor. Varification of the algoithm is presented through digital computer numerical simulation using electromagnetic transients program(EMTP).

거리계전기법 적용을 위한 고장발생시 잡음의 모델링

신명철,김철환 成均館大學校 科學技術硏究所 1989 論文集 Vol.40 No.1

A more specialized area of transient evaluations is transmission line fault detection and protection systems. During the first cycle or two following a power system fault, a high-speed protective relay is expected to make a decision as to the severity or location of the fault, usually based on 60 HZ information, i.e. the phase and magnitude of 60HZ voltage or current signals. However, the signal is badly corrupted by noise in the form of a dc offset or frequencies above 60HZ. Furthermore, fault-induced signals are influenced by the line length, conductor configuration and the nature of the earth return. One of several possible sources of transients in protection measuring signals is in the primary system for which protection is required in its response to the impact of short circuit fault on-set. Other sources are in the primary voltage and current transducers from which protection signals are derived, and, often of particular importance, in the interface circuits between the transducer secondaries and the comparator and measuring elements of the protection system. However, the noise signals that will be described in this paper are due to the main power system only and do not include errors due to current or voltage transducers.

디지탈 계전기법에 의한 전선로 보호의 최적화

신명철,김철환,성낙환 成均館大學校 科學技術硏究所 1990 論文集 Vol.41 No.1

To maintain the high reliability and stability in the large scale electric power system for a stabilized power supplying, it requires an accurate high speed digital distance relaying techniques. For this purpose, when it comes to faults with the power system, the digital distance relaying techniques must be investigated to extract the fundamental frequency component and to predict fault location. In this thesis, it is presented the methodology of DFT(discrete Fourier transform), which accompanied aliasing, picket -fence effect, and leakage in the process of extracting fundamental frequency component and an algorithm of extracting fundamental frequency component, using the Kalman filter theory to improve upon these disadvantages. Also, a two-state and three---state Kalman filter are considered for the symmetrical components estimatin of voltages and currents respectively. It is presented an efficient digital distance relaying techniques for the purpose of extracting fundamental frequency component. Also, to confirm the validity of Kalman filtering techniques, it is shown the experimental results obtained by using the digital simulation of power system. And, it is discussed the extracted results of fundamental frequency components by means of the Fourier transform and Kalman filtering techniques.

전력계통의 실시간 대칭성분 계산을 위한 알고리즘에 관한 연구

신명철,이복구,성낙환 成均館大學校 科學技術硏究所 1987 論文集 Vol.38 No.1

Nowadays as the power systems have been more complicated and have grown to ultra high voltage, it requires an accurate and high speed relaying scheme to improve the reliablity and stability of power systems for a harmonious power supplying. This paper presents a real-time algorithm for calculating symmetrical components from the distorted transient voltage and current signals in a power system. To compute the sequence components and hence to analyze the nature of the disturbance it is necessary to extract the fundamental frequency signals from the noise-ridden transient signals. The fundamental frequency components are filtered out from the transient signals using discrete Fourier technique. The fundamental frequency components of the 3-phase signals are first extracted using an algorithm based on discrete Fourier transformation and then real-time symmetrical components transformation is applied to obtain the sequence components. The algorithm presented is computationally efficient and fast. Experiment results on artificial transmission line demonstrate the validity of the proposed algorithm.

디지탈 보호계전을 위한 칼만필터링기법

申明澈,金喆煥 제주대학교 1991 논문집 Vol.32 No.-

본 연구에서는 디지탈 거리계전 알고리즘으로 널리 이용되어온, DFT를 이용한 대칭성분 거리계전 알고리즘이 기본파 전압, 전류 추출과정에서 Aliasing, Picket-fence effect 및 Leakage 등에 의한 단점을 가지므로, 효율적인 거리계전 알고리즘을 개발하기 위해 필터링 방법의 개선을 시도하였다. 그러므로, 본 연구에서는 칼만 필터링 기법을 도입하여 기본파 성분을 추출함으로써 다음과 같은 결론을 얻었다. (1) 고장발생시 전압과 전류의 비 기본파 성분을 잡음으로 처리하여, 측정치로 부터 잡음을 제거할 수 있는 칼만필터를 이용하여 기본파 성분만을 추출할수 있는 알고리즘을 제시하였다. (2) 2차, 3차 칼만필터 모델을 이용하여 기본파 성분을 추출하고, 그 결과로 부터 대칭성분을 산정함으로써 본 연구에서 제안한 방법이 DFT를 이용한 기법임을 증명하였다. (3) DFT방법에 부수되는 Aliasing, Picket-fence effect 및 Leakage 등의 단점을 제거하기 위하여, 종래에 사용되여 왔던 아날로그 필터나 샘플링율 변경 등의 방법을 이용하지 않고도, 칼만 필터링 기법을 이용함으로써 해결이 가능함을 제시하였다. (4) 송전선로상에서 고장발생시 본 연구에서 제시한 칼만필터를 이용한 디지탈 거리계전 기법을 적용함으로써, 선로의 고장점을 추정하고, 고장상을 판별하여 송전선로에 설치된 차단기에 적절한 트립 명령을 보내어 차단시킴으로써, 고장구간이 건전구간에 미치는 악영향을 감소시킬 수 있는 일련의 알고리즘을 개발하였다. 위와 같은 결과를 얻기 위하여 EMTP를 이용한 디지탈 시뮬레이션을 통해 고장거리, 고장형태, 고장 발생각, 고장저항등을 다양하게 변경시켜 72번의 시뮬레이션을 수행하였다. 이 과정은 대량의 데이타와 다양한 조건들을 취급하여야 하므로, 컴퓨터 수행시간 뿐만 아니라 자료의 처리시간이 많이 소요되는 애로점이 있었다. 추후 연구되어야 할 과제로는 본 연구에서 고려하지 못한 조건들까지 고려하여 전압과 전류의 잡음신호를 산출하고, 필터링 방법도 적응 칼만필터(adaptive Kalman filter)와 같은 기법을 사용하면 더욱 우수한 결과를 얻을 수 있으리라 여겨진다. 또한 본 연구는 오프-라인으로 수행되었으나 온-라인으로 수행시키는 과제도 연구되어야 할 것이다. In this study, Kalman filtering theory is applied to the estimation of symmetrical from fault voltage and current signal when it comes to faults with the power system. Kalman filtering method which was presented by R.E. Kalman has been extensively used in many field for estimating the necessary components from the noisy measurement data. An algorithm for estimating fault location accurately and quickly by calculating the symmetrical components from the extracted fundamental voltage phasor and current phasor is presented. Also, to confirm the validity of digital distance relaying techieques using Kalman filitering, it is shown the experimental results obtained by using the digital simulation of power system.

설근부종양 절제시 측인두 접근법의 의의

노환중,윤종근,왕수건,전경명 釜算慶南耳鼻咽喉科學會 1996 임상이비인후과 Vol.7 No.2

Coats Electrode를 이용한 고막외적 유도법에 의한 전기와우도

전경명,고의경,윤종근,노환중 釜算慶南耳鼻咽喉科學會 1994 임상이비인후과 Vol.5 No.2

EMTP MODELS를 사용한 거리계전기법 구현에 관한 연구

이명희,최해술,서용필,김철환 成均館大學校 科學技術硏究所 1995 論文集 Vol.46 No.2

This paper presents a new distance relay modeling techniques which avoids unnecessary computational procedure. A general-purpose simulation language, called MODELS, has been added to the software ATP(Alternative Transients Program) providing a new option to perform numerical and logical manipulations of variables of an electrical system. This language has been designed to replace the previous option TACS(Transient Analysis of Control Systems) which permits to simulate a control system in conjunction with a large power network. One purpose of this study is to build a structure for modeling of digital distance relays within EMTP MODELS. Contrary to the traditional methods, the new method using MODELS reduce the number of simulation steps in modeling the distance relay.

Hartley변환을 이용한 대칭성분 추출에 관한 연구

김철환,신명철 成均館大學校 科學技術硏究所 1992 論文集 Vol.43 No.2

This paper presents a Hartley transform-based algorithm for calculating symmetrical components from the distorted transient voltage and current signals in a power system. The fundamental frequency components of the 3-phase signals are first extracted using an algorithm based on Hartley transform and symmetrical component transformation is applied to obtain the sequence components. The presented algorithm is computationally efficient and fast. Also, it is shown the experimental results obtained by using the digital simulation of power system to confirm the validity of proposed alogrithms.