• Title/Summary/Keyword: Islanding

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Islanding Prevention Method for Photovoltaic System by Harmonic Injection Synchronized with Exciting Current Harmonics of Pole Transformer

  • Yoshida, Yoshiaki;Fujiwara, Koji;Ishihara, Yoshiyuki;Suzuki, Hirokazu
    • Journal of international Conference on Electrical Machines and Systems
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    • v.3 no.3
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    • pp.331-338
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    • 2014
  • When large penetration of the distributed generators (DGs) such as photovoltaic (PV) systems is growing up in grid system, it is important to quickly prevent islanding caused by power system fault to ensure electrical safety. We propose a novel active method for islanding prevention by harmonic injection synchronized with the exciting current harmonics of the pole transformer to avoid mutual interference between active signals. We confirm the validity of the proposed method by performing the basic tests of islanding by using a current source superimposed the harmonic active signal. Further, we carry out the simulation using PSCAD/EMTDC, and verify the fast islanding detection.

Novel Islanding Detection Method for Distributed PV Systems with Multi-Inverters

  • Cao, Dufeng;Wang, Yi;Sun, Zhenao;Wang, Yibo;Xu, Honghua
    • Journal of Power Electronics
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    • v.16 no.3
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    • pp.1141-1151
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    • 2016
  • This study proposes a novel islanding detection method for distributed photovoltaic (PV) systems with multi-inverters based on a combination of the power line carrier communication and Sandia frequency shift islanding detection methods. A parameter design method is provided for the novel scheme. On the basis of the designed parameters, the effect of frequency measurement errors and grid line impedance on the islanding detection performance of PV systems is analyzed. Experimental results show that the theoretical analysis is correct and that the novel method with the designed parameters has little effect on the power quality of the inverter output current. Non-detection zones are not observed, and a high degree of reliability is achieved. Moreover, the proposed islanding detection method is suitable for distributed PV systems with multi-inverters.

A Study of Islanding Detection of Grid-connected Three-phase Photovoltaic Power Conditioning System

  • Jung Y.S.;Yu G.J.;Choi J.Y.;Choi J.H.
    • Proceedings of the KIPE Conference
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    • pp.761-764
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    • 2003
  • Islanding phenomenon of a grid-connected photovoltaic (PV) power conditioning system (PCS) is said to occur if the PCS continues to power a section of the utility system after that section has been disconnected from the utility source. Since islanding creates hazards for personnel and equipment, PCSs are required to detect and prevent Et. In this paper, several islanding detection methods (IDMs) and reactive power variation method are described. Islanding test results for 9kW PCS are presented for verification.

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Overvoltage Protection Controller Design of Distributed Generation Connected to Power Grid Considering Islanding Condition

  • Cha, Jae-Hun;Park, Kyung-Won;Ahn, Hong-Seon;Kwon, Kyoung-Min;Oh, Jin-Hong;MAHIRANE, Philemon;Kim, Jae-Eon
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.599-607
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    • 2018
  • Distributed generation (DG) is being highlighted as an alternative for future power supplies, and the number of DG systems connected to conventional power systems is steadily increasing. DG generators are designed using power electronics and can give rise to various power quality problems, such as overvoltage or overcurrent. Particularly, unintentional islanding operation can occur in a conventional power system when the power grid is separated from the DG systems. Overvoltage may occur in this situation, depending on the power generation and power consumption. However, overvoltage phenomena might not happen even when islanding occurs. Therefore, it is necessary to analyze the fault characteristics during islanding. In this study, a fault analysis of islanding operation was carried out using PSCAD/EMTDC, and a countermeasure for the overvoltage problem is proposed.

A Novel Method for Anti-Islanding Using Reactive Power Control (무효전력 제어를 통한 새로운 독립운전 검출법)

  • Jeong Jin-Beom;Choi Bong-Ju;Ahn Kang-Soon;Kim Hee-Jun
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.4
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    • pp.208-216
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    • 2005
  • Recently, the study of islanding phenomenon, maintains its operation even when the utility grid is removed has lead to the trend of utility interactive inverters in photovoltaic generation systems. In this paper, a novel Anti-islanding method is presented. the proposed method can keep the real average power component constant by MPPT control and cause the load current frequency with only change of reactive power component under the islanding condition. its periodical change of Reactive power component can decrease the NDZ(Non-Detective zone) so that the detection of various loads will be possible. the insufficient effect if additional reactive power component to the grid is proved theoretically and the islanding detection is also confirmed from a experimental result with a inverter for 3kW photovoltaic generation system applied the proposed Anti-islanding method.

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

  • Eun Suk-Jun;;;Lee Dong-Chun
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.6
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    • pp.294-302
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    • 2005
  • 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 in 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. This paper shows the simulation and comparision for the previous active methods and novel islanding detection method using frequency drift is proposed for grid-connected PV system.

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.

A Novel Anti-islanding Algorism for Utility Interconnection of PV System (PV 시스템의 계통연계를 위한 새로운 고립운전 방지 알고리즘)

  • Yun, Jung-Hyeok;Kim, Heung-Geun;Choi, Jong-Woo;Yu, Gwon-Jong
    • Proceedings of the KIEE Conference
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    • pp.271-273
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    • 2005
  • Islanding of PV systems occurs when the utility grid is removed but local sources continue to operate and provide power to local loads. Islanding is one of the serious problems in 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 phenomena can't be detected by the passive methods. Several active methods were proposed to detect islanding phenomena. The most effective method is SFS method which was suggested by Sandia National Laboratory. In this paper, a new anti-islanding algorithm is proposed and its validity is verified through simulation and experimental results for utility interconnection of PV system.

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Islanding detection of grid-connected photovoltaic inverters using Automatic phase-shift method (계통연계형 PV 인버터의 자동 위상 이동법에 의한 고립운전 검출)

  • Yun, Jung-Hyeok;Kim, Heung-Geun;Choi, Jong-Woo;Chun, Tae-Won;Lee, Hong-Hee
    • Proceedings of the KIPE Conference
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    • pp.591-594
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    • 2005
  • Islanding of PV systems 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 in an electric power system connected with dispersed power sources. Also, this scan 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 phenomena can't be detected by the passive methods. Several active methods were proposed to detect islanding phenomena. The most effective method is SFS method which was suggested by Sandia National Laboratory. In this paper, a new anti-islanding algorithm is proposed and its validity is verified through simulation and experimental results for utility interconnection of PV system.

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Development of a Islanding Protection Algorithm for Distributed Resources (분산 전원의 고립 운전 진단 알고리즘 개발)

  • Jang, S.I.;Park, J.Y.;Kim, K.H.
    • Proceedings of the KIEE Conference
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    • pp.1287-1289
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    • 2001
  • This paper presents the logic based islanding protection algorithm for distributed resources(DR) which are interconnected with distribution network. Due to the negative impacts from islanding operations of DR on protection, operation and management of distribution system, it is necessary to effectively detect the islanding operations of DR and disconnect it from distribution network rapidly. Generally, it is difficult to detect islanding operation by monitoring only one system parameter. The proposed islanding protection algorithm utilizes multi-criteria, voltage variation, phase displacement frequency variation, the variation of total harmonic distortion(THD) of current; therefore it effectively detects island operation of DR unit. We also verified the efficiency of the proposed algorithm using the radial distribution network of IEEE 34 bus model.

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