• Title, Summary, Keyword: power method

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Active Frequency Drift Method for Islanding Detection Applied to Micro-inverter with Uncontrollable Reactive Power

  • Kwak, Raeho;Lee, June-Hee;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.16 no.5
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    • pp.1918-1927
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    • 2016
  • This paper proposes active frequency drift (AFD) as an anti-islanding method applied to micro-inverters with uncontrollable reactive power. When using ordinary inverter topologies, such as full bridge inverters in photovoltaic systems, the islanding phenomenon can be detected with reactive power-based methods, such as reactive power variation. However, when the inverter topology cannot control the reactive power, conventional anti-islanding methods with reactive power cannot be utilized. In this work, the topology used in this paper cannot control the reactive power. Thus, an anti-islanding method that can be used in topologies that cannot control the reactive power is proposed. The conventional anti-islanding method of the topology that cannot control reactive power is introduced and analyzed. Unlike the conventional AFD method, the proposed method extends a zero current interval every predetermined cycle. The proposed method offers certain advantages over conventional AFD methods, such as total harmonic distortion. The proposed method is validated through simulation and experiment.

New Method for MPPT Control of Photovoltaic System (태양광전시스템의 최대출력점추적제어를 위한 새로운 방식)

  • Chung, C.B.;Jho, J.H.;Jho, J.M.;Jeon, K.Y.;Lee, S.H.;Oh, B.H.;Kim, Y.J.;Han, K.H.
    • Proceedings of the KIEE Conference
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    • pp.1256-1258
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    • 2003
  • The solar cells should be operated at the maximum power point because its output characteristics are greatly fluctuate on the variations of insolation, temperature and loads. To obtain maximum power from solar cell, photovoltaic system cell power system usually requires maximum power point tracking controller. This paper propose Maximum power point tracking method using zero slope of differential value of maximum power. The power compare method traces to maximum power point rapidly but oscillate on the maximum power point largely, when quantity insolation variation is big. The power compare method is traces to maximum power point slowly but oscillate maximum point on the maximum power point smally, when quantity insolation variation is small. To solve two problem of the power compare method, designed zero slope of differential value of maximum power.

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PNN based Rogers Diagnosis Method for Fault Classification of Oil-filled Power Transformer (유입변압기 고장분류를 위한 PNN 기반 Rogers 진단기법 개발)

  • Lim, Jae-Yoon;Lee, Dae-Jong;Ji, Pyeong-Shik
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.65 no.4
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    • pp.280-284
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    • 2016
  • Stability and reliability of a power system in many respects depend on the condition of power transformers. Essential devices as power transformers are in a transmission and distribution system. Being one of the most expensive and important elements, a power transformer is a highly essential element, whose failures and damage may cause the outage of a power system. To detect the power transformer faults, dissolved gas analysis (DGA) is a widely-used method because of its high sensitivity to small amount of electrical faults. Among the various diagnosis methods, Rogers diagonsis method has been widely used in transformer in service. But this method cannot offer accurate diagnosis for all the faults. This paper proposes a fault diagnosis method of oil-filled power transformers using PNN(Probability Neural Network) based Rogers diagnosis method. The test result show better performance than conventional Rogers diagnosis method.

A Study on the Loop Current Induced by Voltage Phase Difference Substations during Parallel Feeding under the Alternating Current AT Electric Power Feeding Method (교류 AT급전방식에서 병렬급전시 변전소간 전압위상차에 의한 루프전류에 관한 연구)

  • Park, Jae-Seok;Song, Joong-Ho
    • Proceedings of the KSR Conference
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    • pp.1997-2004
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    • 2011
  • The $2{\times}25kv$ AT electric power feeding method in the A.C. electric train adopts the one-phase power feeding method as the standard due to a voltage phase difference, and the distance between the two neighboring substations is 50km due to voltage drop. The one-phase power feeding method makes the system operation feasible, while making it unfavorable for power supply. Moreover, railroad involves large-capacity single-phase load, and if it is expected to continue to rise, it is necessary to research on measures to stabilize the supply of power to railroad cars with the existing facilities. In this study, a parallel power feeding method between neighboring substations is proposed to stabilize the supply of electric power to electric railroad cars under the 2*25kv AT power feeding method and the loop current induced by voltage phase difference between the two neighboring substations during parallel power feeding is investigated.

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Introduction of Power Flow Tracing Method for Determination of Power Transmission Network Charge and Verification of Its Effectiveness (송전요금 결정을 위한 전력조류 추적법의 도입 및 효용성 검증)

  • No, Gyeong-Su
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.2
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    • pp.53-58
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    • 2002
  • This paper describes methodologies to charge for power transmission network use. These methodologies are normally divided into two categories such as marginal cost method and embedded cost allocation method. This paper, first, discusses the possible problems that can occur when the marginal cost method is applied to pricing the transmission services. Next, the paper proposes a method to apply the electricity tracing method to the transmission network charge. The result of the electricity tracing method is then used in MW-mile method to charge individual loads for the use of transmission network. Effectiveness of the algorithm is verified by computer simulations and it is estimated that the results can be used to compute the cost of electric power transmission under deregulated environment in electric power industries.

Power Line Communication Method with Splitting of Power Transmission Interval (전력전송구간을 분할하여 데이터 신호를 전송하는 전력선 통신방법)

  • Cho, Jae-Seung;Hwang, Il-Kyu
    • The Transactions of the Korean Institute of Power Electronics
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    • v.17 no.3
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    • pp.252-258
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    • 2012
  • This paper studies the power line communication method with splitting of power transmission interval in the small DC power system using pulse width modulation. The method divides the entire interval for transmitting power and data into a power transmission interval where power is supplied to a load and a data transmission interval where power from the power supply to the load is disconnected. The circuit is designed for the implementation to separate the power line from the power supply and load. The results of tests show the feasibility of the proposed power line communication method.

A Study on the Optimal Reactive Power Calculation Method of Induction Generator for Marine Small Hydraulic Power (해양 소수력발전용 유도발전기의 최적 무효전력 산정방식에 관한 연구)

  • Lee, Won-Jae;Oh, Yong-Taek
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.9
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    • pp.100-107
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    • 2013
  • Since the West Sea experiences a big difference in tides, the output power of the small marine hydroelectric power plant varies with the tide. When an induction generator is used here for small hydroelectric power, the reactive power capacitor should be installed at the generator main bus to compensate for the changes in power. As such, the sizing method for the power compensation of the induction generator is reviewed and an optimal method for compensation is suggested. The self-excitation minimum capacitor capacity method, which prevents high voltages, and the power factor automatic control method, which retains a power factor of greater than 90% are reviewed. The compensation effect of reactive power is confirmed through a case study.

Instantaneous Compensating Power Flow Graph of Active Power Filters Considering Rectification / Inversion Modes (정류와 역변환 모드를 고려한 능동전력필터의 순시 보상전력 흐름도)

  • 정영국;정찬수;배동관;안재영;김광헌;임영철
    • Proceedings of the KIPE Conference
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    • pp.101-105
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    • 1999
  • The goal of this paper is to present instantaneous compensating power flow of active power filters(APFs) by graphical method that could be practicable to compensate the power in both case of behaving in instantaneous rectifying mode and instantaneous inverting mode. To ensure the validity of the proposed method, computer simulation is achieved. Proposed method can be present more exquisite and physically meaningful power flow than conventional method in instantaneous compensating power flow Graph of APFs.

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Analysis of Nigeria Research Reactor-1 Thermal Power Calibration Methods

  • Agbo, Sunday Arome;Ahmed, Yusuf Aminu;Ewa, Ita Okon Bassey;Jibrin, Yahaya
    • Nuclear Engineering and Technology
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    • v.48 no.3
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    • pp.673-683
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    • 2016
  • This paper analyzes the accuracy of the methods used in calibrating the thermal power of Nigeria Research Reactor-1 (NIRR-1), a low-power miniature neutron source reactor located at the Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria. The calibration was performed at three different power levels: low power (3.6 kW), half power (15 kW), and full power (30 kW). Two methods were used in the calibration, namely, slope and heat balance methods. The thermal power obtained by the heat balance method at low power, half power, and full power was $3.7{\pm}0.2kW$, $15.2{\pm}1.2kW$, and $30.7{\pm}2.5kW$, respectively. The thermal power obtained by the slope method at half power and full power was $15.8{\pm}0.7kW$ and $30.2{\pm}1.5kW$, respectively. It was observed that the slope method is more accurate with deviations of 4% and 5% for calibrations at half and full power, respectively, although the linear fit (slope method) on average temperature-rising rates during the thermal power calibration procedure at low power (3.6 kW) is not fitting. As such, the slope method of power calibration is not suitable at lower power for NIRR-1.

A Method of Power Transmission Pricing using Power Flow Tracing (전력조류 추적법을 이용한 송전요금 산정법)

  • Ro, Kyoung-Soo
    • Proceedings of the KIEE Conference
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    • pp.424-428
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    • 2001
  • The methodologies of power transmission pricing are normally divided into two categories such as marginal cost method and embedded cost allocation method. This paper, first, discusses the possible problems that can occur when the marginal cost method is applied to pricing the transmission services. Next, the paper proposes a method to apply the power flow tracing to the transmission network charge. The result of the power flow tracing method is then used in MW-mile method to charge individual loads for the use of transmission network. Effectiveness of the algorithm is verified by computer simulations.

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