• Title/Summary/Keyword: Ground faults

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Analysis on Fault Current Limiting Characteristics of Three-Phase Transformer Type SFCL using Double Quench According to Three-Phase Ground-Fault Types (이중퀜치를 이용한 삼상변압기형 초전도한류기의 삼상지락 고장 종류에 따른 고장전류 제한 특성 분석)

  • Shin-Won Lee;Tae-Hee Han;Sung-Hun Lim
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.36 no.6
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    • pp.614-619
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    • 2023
  • The fault current limiting characteristics of three-phase transformer type superconducting fault current limiter (SFCL), which consisted of three-phase primary and secondary windings wound on E-I iron core, one high-TC superconducting (HTSC) element connected with the secondary winding of one phase and another HTSC element connected in parallel with other two secondary windings of two phases, were analyzed. Unlike other three-phase transformer type SFCLs with three HTSC elements, three-phase transformer type SFCL using double quench has the merit to perform fault current limiting operation for three-phase ground faults with two HTSC elements. To verify its proper three-phase ground fault current limiting operation, three-phase ground faults such as single-line ground, double-line ground and triple-line ground faults were generated in three-phase simulated power system installed with three-phase transformer type SFCL using double quench. From analysis of its fault current limiting characteristics based on tested results, three-phase transformer type SFCL using double quench was shown to be effectively operated for all three-phase ground faults.

Improvement of the Protection Algorithm Based on Voltage Difference Method for Detecting Arcing Faults within 22.9kV Shunt Capacitor Banks (22.9kV급 병렬 커패시터 뱅크 내부의 아크 고장 판별을 위한 전압차동 보호 알고리즘의 개선 방안)

  • Lim Jung-Uk;Kwon Young-Jin;Kang Sang-Hee;Yuk Yoo-Kyoung
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.2
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    • pp.61-66
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    • 2005
  • This paper presents a refined protection algorithm of the unfused 22.9kV shunt capacitor banks in grounded wye connection to improve the existing algorithm using the voltage difference method. It is difficult to detect ground faults with arc near the input points or ground faults near the grounding point by the existing algorithm using only the voltage balanced relay. This paper shows that ground faults with arc near the input point can be detected by harmonics analysis of the differential voltage and that it has no impact of harmonics out of nonlinear loads which have the quantitative influence on capacitor banks. Thus the proposed method using harmonics analysis can be a proper detection method. In case of ground faults near the grounding point, an OVGR is being added recently and its validity is verified in this paper. The proposed method is applied to a 22.9kV example system and is verified that the proposed algorithm can detect clearly faults which are not easy to detect by the existing method.

Development of Control Algorithm and Detection of the Small Leakage Current (미소 누전전류 검출 및 차단제어기 설계)

  • 반기종;김낙교
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.3
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    • pp.161-165
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    • 2004
  • In this paper, we have designed the ground faults detection and interrupting controller at normal condition of AC 120v to 240v rating voltage. Ground faults in electrical network have the characteristics of low current, 60㎐ frequency to 2㎑frequency. The load condition are no load and 20A load. The trip level of the controller is 6㎃ with ground faults. The Controller algorithm is implemented using pic16c71 microprocessor.

Leakage Currents Flowing through Lightning Surge Arresters under Various Fault Conditions in Receiving and Distribution Power Systems (수배전계통의 여러 가지 고장조건에서 피뢰기에 흐르는 누설전류)

  • Lee, Bok-Hee;Kil, Hyeong-Joon;Kang, Sung-Man;Choi, Hwee-Sung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.5
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    • pp.132-139
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    • 2004
  • Unsymmetrical faults are classified into single line-to-ground faults, line-to-line faults, or double line-to-ground faults in receiving and distribution power systems. Many of overhead distribution-line faults are single line-to-ground faults, and lightning surge arresters are stressed by system frequency overvoltages due to unsymmetrical faults. In this work, the unsymmetrical faults in receiving and distribution systems were experimentally simulated, and the characteristics of total leakage current flowing through lightning surge arresters due to various unsymmetrical faults were investigated. As a result, a little variations of the leakage current flowing through Zinc oxide (ZnO) surge arresters in the range of $\pm$10[%] voltage regulations were observed. It could be concluded that the unsymmetrical faults have no effect on the long-term life performance of ZnO surge arresters in effective grounding systems. On the other hand, the magnitude of the leakage current flowing through ZnO surge arrester elements under single line-to-ground faults was more than 140 times as compared with that under normal operating voltages in ineffective grounding systems. But abnormal voltages caused by line-to-line faults and double line-to-ground faults have a little effect on total leakage current of ZnO surge arrester elements.

Case Study of Derivation of Input-Parameters for Ground-Structure Stability on Foliation-Parallel Faults in Folded Metamorphic Rocks (단층 발달 습곡지반 상 구조물 안정성을 위한 설계정수 도출 사례 연구)

  • Ihm, Myeong Hyeok
    • The Journal of the Convergence on Culture Technology
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    • v.6 no.2
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    • pp.467-472
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    • 2020
  • Methods for deriving design input-parameters to ensure the stability of a structure on a common ground are generally well known. Folded metamorphic rocks, such as the study area, are highly foliated and have small faults parallel to the foliation, resulting in special research methods and tests to derive design input parameters, Etc. are required. The metamorphic rock ground with foliation development of several mm intervals has a direct shear test on the foliation surface, the strike/dip mapping of the foliation, the boring investigation to determine the continuity of the foliation, and the rock mass rating of the metamorphic rock. etc. are required. In the case of a large number of small foliation-parallel faults developed along a specific foliation plane, it is essential to analyze the lineament, surface geologic mapping for fault tracing, and direct shear test. Folded ground requires additional geological-structural-domain analysis, discontinuity analysis of stereonet, electrical resistivity exploration along the fold axis, and so on.

Characteristic Analysis of Voltage Sags Due to Faulted Distribution Lines (배전선로 고장에 의한 Voltage Sag의 특성 해석)

  • ;Madhat M. Morcos
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.1
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    • pp.76-84
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    • 2002
  • Voltage sags caused by line faults in transmission and distribution lines have become one of the most important power quality problems facing industrial customers and utilities. Voltage sags are normally described by characteristics of both magnitude and duration, but phase angle shifts should be taken account in identifying sag phenomena and finding their solutions. In this paper, voltage sags due to line faults such as three phase-to-ground, single line-to-ground, and line-to-line faults are characterized by using symmetrical component analysis, for fault impedance variations. Voltage sags and their effect on the magnitude and phase angle are examined. Balanced sags of three phase-to-ground faults show that voltages and currents are changed with equivalent levels to all phases and the zero sequence components become zero. However, for unbalanced faults such as single line-to-ground and line-to-line faults, voltage sags give different magnitude variations and phase angle shifts for each phase. In order to verify the analyzed results, some simulations based on power circuit models are also discussed.

A Study on the Ground Fault Current Distribution by Single Phase-to-Neutral Fault Tests in Power Distribution System (배전계통에서 1선 지락고장 시험에 의한 지락고장전류 분류에 관한 연구)

  • Kim, Kyung-Chul;You, Chang-Hun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.7
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    • pp.37-44
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    • 2013
  • Phase to ground faults are possibly one of the maximum number of faults in power distribution system. During a ground fault the maximum fault current and neutral to ground voltage will appear at the pole nearest to the fault. Distribution lines are consisted of three phase conductors, an overhead ground wire and a multigrounded neutral line. In this paper phase to neutral faults were staged at the specified concrete pole along the distribution line and measured the ground fault current distribution in the ground fault current, three poles nearest to the fault point, overhead ground wire and neutral line. A simplified equivalent circuit model for the distribution system under case study calculated by using MATLAB gives results very close to the ground fault current distribution yielded by field tests.

Sensitivity Analysis of Finite Fault Model in Stochastic Ground Motion Simulations (추계학적 지진동 모사에서 유한단층 모델의 민감도 분석)

  • Lee, Sang-Hyun;Rhie, Junkee
    • Journal of the Earthquake Engineering Society of Korea
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    • v.28 no.3
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    • pp.159-164
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    • 2024
  • Recent earthquakes in Korea, like Gyeongju and Pohang, have highlighted the need for accurate seismic hazard assessment. The lack of substantial ground motion data necessitates stochastic simulation methods, traditionally used with a simplistic point-source assumption. However, as earthquake magnitude increases, the influence of finite faults grows, demanding the adoption of finite faults in simulations for accurate ground motion estimates. We analyzed variations in simulated ground motions with and without the finite fault method for earthquakes with magnitude (Mw) ranging from 5.0 to 7.0, comparing pseudo-spectral acceleration. We also studied how slip distribution and hypocenter location affect simulations for a virtual earthquake that mimics the Gyeongju earthquake with Mw 5.4. Our findings reveal that finite fault effects become significant at magnitudes above Mw 5.8, particularly at high frequencies. Notably, near the hypocenter, the virtual earthquake's ground motion significantly changes using a finite fault model, especially with heterogeneous slip distribution. Therefore, applying finite fault models is crucial for simulating ground motions of large earthquakes (Mw ≥ 5.8 magnitude). Moreover, for accurate simulations of actual earthquakes with complex rupture processes having strong localized slips, incorporating finite faults is essential even for more minor earthquakes.

Controller design for Leakage current detection and disconnection (누설전류 검출 및 차단을 위한 제어알고리즘 설계)

  • Ban, Gi-Jong;Yoon, Kwang-Ho;Park, Jin-Soo;Nam, Moon-Hyun;Kim, Lark-Kyo
    • Proceedings of the KIEE Conference
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    • 2003.11c
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    • pp.417-420
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    • 2003
  • In this paper, we have designed the ground faults detection and disconnection algorithm at normal rendition of AC 120V to 240V rating voltage. Ground faults in electrical network have the characteristics of low current, 60Hz frequency to 2kHz frequency. The load rendition are no load and 20A load. The controller have the trip level are 6mA with ground faults. Conventional controller does not have the miswiring condition. The Controller algorithm using pic16c71 microprotessor.

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