• Title/Summary/Keyword: Frequency drift

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Novel Islanding Detection Method using Frequency Drift for Grid-connected PV System (계통연계형 PV 시스템의 주파수 변동에 의한 새로운 단독운전 검출기법)

  • Eun Seog-Jun;Choi Jong-Woo;Kim Heung-Geun
    • Proceedings of the KIPE Conference
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    • pp.133-137
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    • 2004
  • PV system's islanding occurs when the uitilty grid is removed but local sources continue to operate and provide power to local loads. Islanding is one of the serious problems m an electric power system connected with dispersed power sources. Also, this can present safety hazards and the possibility of damage to other electric equipments. If the real and reactive power of RLC load and PV system are closely matched, islanding detection by passive methods becomes difficult. Novel islanding detection method using frequency drift is proposed for grid-connected PV system.

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A Study of Non-Detection Zone using AFD Method applied to Grid-Connected Photovoltaic Inverter for a variety of Loads (계통연계형 태양광발전 인버터에 사용된 AFD기법의 다양한 부하에 따른 단독운전 불검출영역에 대한 고찰)

  • Ko, Moon-Ju;Choy, Ick;Choi, Ju-Yeop
    • Journal of the Korean Solar Energy Society
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    • v.26 no.1
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    • pp.91-98
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    • 2006
  • Islanding phenomenon of utility-connected photovoltaic power conditioning systems(PV PCS) can cause a variety of problems and must be prevented. If the real and reactive power supplied by PV PCS are closely matched to those of load, islanding detection by passive methods becomes difficult. The active frequency drift(AFD) method, called the frequency bias method, enables islanding detection by forcing the frequency of the voltage in the islanding to drift up or down. In this paper, non-detection zone(NDZ) of AFD is analyzed for the islanding detection method of utility-connected PV PCS by the simulation software tool PSIM.

Output Power Analysis for Active Frequency Drift Method (AFD 기법의 출력전력 분석)

  • Lee, Ki-Ok;Choi, Ju-Yeop;Choy, Ick;Yu, Gwon-Jong
    • 한국태양에너지학회:학술대회논문집
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    • pp.297-302
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    • 2009
  • As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, these have raised potential problems of network protection on electrical power system. One of the numerous problems is an Islanding phenomenon. In this paper, active frequency drift (AFD) method, one of the anti-islanding analyzed by current magnitude compensation and calculation of RMS value of the output power.

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Design Method for Frequency Drift Anti-islanding Detection Method Based on Analysis of Non Detection Zone (불검출 영역 분석을 통한 주파수 이동 단독 운전 검출 기법의 설계 방법)

  • Kim, Byeong-Heon;Sul, Seung-Ki
    • Proceedings of the KIPE Conference
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    • pp.9-10
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    • 2012
  • AFD(Active Frequency Drift), SMS(Slip-Mode frequency Shift)를 비롯한 주파수 이동 단독 운전 검출 방법은 단독 운전 발생 후, 계통의 주파수를 정상 운전 범위 밖으로 이동시켜 OUF(Over/Under Frequency) 릴레이를 동작하게 만들어 단독 운전을 검출한다. 이 방법들의 불검출 영역은 알고리즘에 의한 전류 위상각 변화율과 부하 역률 각 변화율 사이의 관계, 그리고 단독 운전 후 정상 상태(steady state) 운전 주파수에 의해 결정된다. 본 논문에서는 불검출 영역에 영향을 미치는 부하 역률 각 변화율을 분석하고 그를 바탕으로, 설계한 Q(Quality)-factor보다 낮은 Q-factor를 갖는 부하 조건에서는 항상 단독 운전을 검출할 수 있는 설계 방법을 제시한다. 제안된 방법의 유효성은 모의실험 및 실험으로 검증되었다.

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A New Simplified Clock Synchronization Algorithm for Indoor Positioning (실내측위를 위한 새로운 클락 동기 방안)

  • Lee, Young-Kyu;Yang, Sung-Hoon;Lee, Seong-Woo;Lee, Chang-Bok;Kim, Young-Beom;Choe, Seong-Su
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.3A
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    • pp.237-246
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    • 2007
  • Clock Synchronization is one of the most basic factors to be considered when we implement an indoor synchronization network for indoor positioning. In this paper, we present a new synchronization algorithm which does not employ time stamps in order to reduce the hardware complexity and data overhead. In addition to that, we describe an algorithm that is designed to compensate the frequency drift giving an serious impact on the synchronization performance. The performance evaluation of the proposed algorithm is achieved by investigating MTIE (Maximum Time Interval Error) values through simulations. In the simulations, the frequency drift values of the practical oscillators are used. From the simulation results, it is investigated that we can achieve the synchronization performance under 10 ns when we use 1 second synchronization interval with 1 ns resolution and TCXOs (Tmperature Compensated Cristal Oscillators) both in the master clock and the slave clock.

Simulation of Non-Detection Zone using AFD Method applied to Utility-Connected Photovoltaic Systems for a Variety of Loads (다양한 부하에 따른 계통연계형 태양광발전 시스템에 적용된 AFD 기법의 단독운전 불검출영역 시뮬레이션)

  • Ko, Moon-Ju;Choy, Ick;Choi, Ju-Yeop;Won, Young-Jin
    • 전자공학회논문지 IE
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    • v.43 no.2
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    • pp.63-69
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    • 2006
  • Islanding phenomenon of utility-connected PV power conditioning systems(PV PCS) can cause a variety of problems and must be prevented. If the real and reactive powers supplied by PV PCS are closely matched to those of load, islanding detection by passive methods becomes difficult. The active frequency drift(AFD) method, called the frequency bias method, enables islanding detection by forcing the frequency of the voltage in the islanding to drift up or down. In this paper, non-detection zone(NDZ) of AFD is analyzed for the islanding detection method of utility-connected PV PCS by simulation tool PSIM.

Novel AFD method of islanding detection with a periodic zero current for improving on islanding detection for grid-connected Photovoltaic inverters (계통연계형 태양광발전 인버터를 위한 주기적인 영전류 구간을 가지는 새로운 AFD 단독운전 검출기법)

  • Ko, Moon-Ju;Choy, Ick;Choi, Ju-Yeop;Song, Seung-Ho;Lee, Ki-Ok
    • Journal of the Korean Solar Energy Society
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    • v.26 no.4
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    • pp.17-23
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    • 2006
  • This paper proposes a novel active frequency drift (AFD) method for the islanding prevention of grid-connected photovoltaic inverter. To detect the islanding phenomenon of grid-connected photovoltaic (PV) inverters concerning about the safety hazards and the damage to other electric equipments, many kinds of anti-islanding methods have been presented. Among them, AFD method using chopping fraction enables the islanding detection to drift up (or down) the frequency of the voltage during the islanding situation. In this paper, injecting the periodic zero current into the basic AFD method is proposed. This proposed method shows the analytical design value of cf to meet the test procedure of IEEE Std. 1547 with various load conditions. Detection of islanding is verified using simulation tool PSIM.

Active Frequency Drift Positive Feedback Method for Anti-islanding (단독운전검출을 위한 능동적 주파수 변화 정궤환기법)

  • So, J.H.;Jung, Y.S.;Yu, G.J.;Yu, B.G.;Lee, K.O.;Choi, J.Y.
    • Proceedings of the KIEE Conference
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    • pp.1684-1686
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    • 2005
  • As photovoltaic(PV) power generation systems become more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive power of load and PV system are closely matched, islanding detection by passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop(DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment in IEEE Std 929-2000 islanding test.

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Comparison of Three Active-Frequency-Drift Islanding Detection Methods for Single-Phase Grid-Connected Inverters

  • Kan, Jia-rong;Jiang, Hui;Tang, Yu;Wu, Dong-chun;Wu, Yun-ya;Wu, Jiang
    • Journal of Power Electronics
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    • v.19 no.2
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    • pp.509-518
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    • 2019
  • A novel islanding detection method is proposed in this paper. It is based on a frequency drooping PLL, which was presented in a previous work. The cause of errors in the non-detection zone (NDZ) of conventional frequency disturbance islanding detection methods (IDM) is analyzed. A frequency drooping phase-locked-loop (FD-PLL) is introduced into a single-phase grid-connected inverter (SPGCI), which can guarantee that grid current is in phase with the grid voltage. A novel FD-PLL IDM is proposed by improving this PLL. In order to verify the performance of the proposed FD-PLL IDM, a full performance comparison between the proposed IDM and typical existing active frequency drift IDMs is carried out, which includes both dynamic performance and steady performance. With the same NDZ, the total harmonic distortion of the grid-current in the dynamic process and steady state is analyzed. The proposed FD-PLL IDM, regardless of the dynamic or steady process, has the best power quality. Experimental and simulation results verify that the proposed FD-PLL IDM has excellent performance.

Development of Novel Algorithm for Anti-Islanding of Grid-Connected PV Inverter (계통연계형 태양광 인버터의 단독운전 방지를 위한 새로운 알고리즘 개발)

  • Choi, Jung-Sik;Ko, Jae-Sub;Chung, Dong-Hwa
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.10
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    • pp.76-86
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    • 2011
  • This paper proposes novel algorithm for anti-islanding of grid-connected photovoltaic(PV) inverter. The islanding of PV systems can cause a variety of problems such as deterioration in power quality and electric shock. To prevent islanding, many anti-islanding methods are researched. Typical methods of anti-islanding are active frequency drift(AFD) and active frequency drift positive feedback(AFDPF). However, the AFD has problem that widely exists non diction zone(NDZ). The AFDPF is a method that improves the AFD method and is detected islanding by changing the chopping fraction(cf). However, The AFDPF does not detect when cf is very small and does not satisfy the IEEE Std. 929-2000 when cf is very big. Therefore, this paper proposes novel anti-islanding method that is simple to implement using virtual resister. The anti-islanding method proposed in this paper is compared with conventional method. The validity of this paper is proved using this result.