• 제목/요약/키워드: Magnetic inrush

검색결과 39건 처리시간 0.023초

EMTP-RV를 이용한 765kV 변압기의 여자 돌입 현상 모의 및 분석 (Simulation and analysis of the magnetic inrush for the 765kV transformer using EMTP-RV)

  • 강용철;이미선;이병은;장성일;김용균;주행로;유영식
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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    • pp.157-159
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    • 2008
  • This paper describes modeling and analysis of magnetic inrush for a 765kV transformer using EMTP-RV. EMTP-RV generates the core flux and thus helps show the behavior of the core, i.e. hysteresis characteristics. The results of three kinds of the magnetic inrush such as initial inrush, sympathetic inrush, and recovery inrush are included. This modelling can help the design of a protection relay for a transformer.

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A Transformer Protection Relay Based on Induced Voltages

  • Kang, Yong-Cheol;Lee, Byung-Eun
    • KIEE International Transactions on Power Engineering
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    • 제3A권2호
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    • pp.70-78
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    • 2003
  • This paper describes a transformer protection relay based on induced voltages. The ratio of the induced voltages of the primary and secondary windings is equal to the turns ratio during normal operating conditions such as magnetic inrush, overexcitation, and steady state, but it differs from the turns ratio in the case of internal faults. For a single-phase and a three-phase Y-Y transformer, the induced voltages are estimated and the ratios are compared with the turns ratio. For three-phase Y-Δ transformers, the differences between the induced voltages are estimated to use the line currents because delta-winding currents are practically unavailable. The proposed relay is tested under various conditions such as magnetic inrush, internal winding faults, overexcitation, and different core characteristics. The results evidently indicate that the relay successfully discriminates internal faults from magnetic inrush and overexcitation. This paper concludes by implementing the relay into a TMS320C6701 digital signal processor and reports satisfactory results. The relay requires no hysteresis data and can reduce the operating time of a relay.

돌입전류의 제어조건 해석 및 돌입전류 발생 확률식의 유도 (An analysis of limiting conditions of excess inrush currents and a derivation of the probability equations of inrush current occurrence)

  • 박영문
    • 전기의세계
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    • 제14권5호
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    • pp.8-14
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    • 1965
  • Because of the flat slope of the magnetic characteristic curves at high saturation, the transformer inrush current peakes may assume an extreme magnitude. Even though such is rarely any danger to the transformer itself, the currents can cause serious problems in associated apparatus. This paper has analyzed various limiting factors of excess inrush currents, and then has suggested how to determine the frequency of encountering the inrush current peaks higher than an arbitrarily chosen value by deriving the probability equations of inrush current occurrence.

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DVR의 특성을 고려한 매칭변압기의 자속포화 해석 (Magnetic Flux Saturation Analysis of Matching Transformer Considering Characteristic of Dynamic Voltage Restorer(DVR))

  • 손진근;김동준;강민구;전희종
    • 전기학회논문지P
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    • 제57권3호
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    • pp.236-243
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    • 2008
  • This paper analyses magnetic flux saturation of matching transformer considering characteristic of dynamic voltage restorer(DVR) system to solve voltage sags which are considered the dominant disturbances affecting power quality. This DVR consist of PWM inverter to inject arbitrary voltage, LC low pass filter and matching transformer for isolation and grid connection. However, the matching transformer has an excess of inrush current by magnetic flux saturation in the core of transformer. Due to this inrush current, the rating of matching transformers is double for needed nominal rating for protection of DVR. Therefore, in this paper, an advanced modeling method of magnetic flux saturation is used to analyze a magnitude and characteristic of magnetizing current. Simulation and experimental results considering characteristic of DVR system are provided to demonstrate the validity of the proposed analysis method.

통계적 방법에 의한 전자레인지의 돌입전류 최적화 연구 (A Study on Optimum control for Inrush current of Microwave Oven using Statistical Method)

  • 이민기;고강훈;권순걸;이현우
    • 조명전기설비학회논문지
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    • 제15권5호
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    • pp.61-67
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    • 2001
  • 여자자속의 포화는 전자레인지에 사용되는 고압 변압기의 초기 입력 전원의 위상에 의존한다. 고압트랜스의 돌입전류를 제한하기 위해서는 릴레이의 접점을 입력전원위상의 최저점일 때 ˝ON˝하여야 한다. 개선된 회로는 보정된 인터럽터 신호를 마이컴의 입력으로서 릴레이의 접점이 돌입전류가 최소 일 때 ˝ON˝한다. 실험결과는 입력전압변동모드에 대해서 개선된 회로가 설계목표치 50[A]를 만족함을 나타내었다. 그리고 통계적 기법으로서 이를 검증한다.

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변압기 보호용 수정 전류차동 계전방식 (A Modified Current Differential Relay for Transformer Protection)

  • 강용철;김은수;원성호
    • 대한전기학회논문지:전력기술부문A
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    • 제53권2호
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    • pp.80-86
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    • 2004
  • During magnetic inrush or over-excitation, saturation of the core in a transformer draws a large exciting current, which can cause mal-operation of a differential relay. This paper proposes a modified current differential relay for transformer protection. The relay calculates core-loss current from the induced voltage and the core-loss resistance; the relay calculates the magnetizing current from the core flux and the magnetization curve. Finally, the relay obtains the modified differential current by subtracting the core-loss and the magnetizing currents from the conventional differential current. Comparison study with the conventional differential relay with harmonic blocking is also shown. The proposed technique not only discriminates magnetic inrush and over-excitation from an internal fault, but also improves the speed of the conventional relay.

Modified-Current-Differential Relay for Transformer Protection

  • Kang Yong-Cheol;Jin En-Shu;Won Sung-Ho
    • KIEE International Transactions on Power Engineering
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    • 제5A권1호
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    • pp.1-8
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    • 2005
  • During magnetic inrush or over-excitation, saturation of the core in a transformer draws a significant exciting current, which can cause malfunction of a current-differential relay. This paper proposes a modified-current-differential relay for transformer protection. The relay calculates the core-loss current from the induced voltage and the core-loss resistance as well as the magnetizing current from the core flux and the magnetization curve. Finally, the relay obtains the modified differential current by subtracting the core-loss and the magnetizing currents from the conventional differential current. A comparative study of the conventional differential relay with harmonic blocking is presented. The proposed relay not only discriminates magnetic inrush and over-excitation from an internal fault, but also improves the relay speed.

자기결합형 고온초전도한류기의 과도전류 해석 (The Analysis of Transient currents in a Magnetic coupling High-Tc superconducting Fault Current Limiter)

  • 주민석;추용;임도현;고태국
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1995년도 하계학술대회 논문집 A
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    • pp.24-26
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    • 1995
  • In this paper, we investigated transient fault currents in a magnetic coupling High-Tc superconducting current limiter(HCL). It has an important effect on the reliability and stability of the power system. In order to analyze transient fault characteristics of HCL, we fabricated a magnetic coupling HCL and tested it in different fault conditions. An important parameter of design and manufacture which makes HCL inherently reliable is reduction of inrush fault currents. Without inrush fault currents, the currents flowing under such conditions can be limited to a desired-value within one cycle. Inrush fault current depends on saturation, normal spot propagation velocity, turns ratio and the fault angle.

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동적전압보상기를 위한 정합 변압기의 돌입전류 제어 (Inrush Current Control of Matching Transformer for Dynamic Voltage Restorer)

  • 서일동;전희종;손진근
    • 전력전자학회논문지
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    • 제11권4호
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    • pp.340-348
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    • 2006
  • 본 논문에서는 동적전압보상기 (DVR)를 구성하기 위한 정합 변압기의 돌입전류 제어기법을 제안하였다. DVR 시스템은 배전계통에서 발생하는 순시적 전압강하를 보상하기 위한 직렬전압 주입장치로서, 임의의 전압을 생성하는 PWM 인버터와 전압 평활용 LC 수동필터 및 절연을 위한 정합 변압기 등으로 구성된다. 그러나 정합 변압기의 사용은 변압기내에서 자속 포화현상에 의하여 정격의 수배에 달하는 돌입전류가 발생하여 시스템의 절연파괴를 초래하고 이 때문에 변압기의 정격용량을 2 배 정도로 초과하여 사용하게 한다. 따라서 본 연구에서는 정합 변압기의 자속 포화현상에 따른 돌입전류의 크기를 분석할 수 있는 새로운 모델링 분석기법 및 돌입전류의 크기를 제한하는 자화전류 제어기법을 제안하였다. 모의실험 및 실험을 통하여 제안된 DVR 제어기법의 타당성을 입증하였다.

잔류자속에 무관한 변압기 보호용 수정전류차동 계전기 (Modified Current Differential Relay for Transformer Protection Unaffected by Remanent flux)

  • 강용철;김은숙
    • 대한전기학회논문지:전력기술부문A
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    • 제53권9호
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    • pp.500-506
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    • 2004
  • This paper proposes a modified current differential relay for transformer protection unaffected by the remanent flux. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. To cope with the remanent flux, before saturation, the relay calculates the core-loss current and uses it to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the actual core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. This paper concludes by implementing the relay on a hardware platform based on a digital signal processor. The relay discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.