Prevention of islanding in grid-connected photovoltaic systems

Ropp, Michael; Begović, Miroslav; Rohatgi, A.

doi:10.1002/(sici)1099-159x(199901/02)7:1<39::aid-pip246>3.0.co;2-j

Cited by 115 publications

(84 citation statements)

References 20 publications

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“…This is done because for most islanding prevention methods it is some type of RLC load that causes the most difficulty in detection. In general, nonlinear loads such as harmonic-producing loads or constant-power loads do not present as much difficulty in islanding prevention [1,2].…”

Section: Methods For Detection Of Islandingmentioning

confidence: 99%

“…To avoid lengthening this report excessively, all of those mappings are not repeated here, but the reader is encouraged to review references [1,2,3]. All grid-connected PV inverters are required to have over/under frequency protection methods (OFP/UFP) and over/under voltage protection methods (OVP/UVP) that cause the PV inverter to stop supplying power to the utility grid if the frequency or amplitude of the voltage at the point of common coupling (PCC) between the customer and the utility strays outside of prescribed limits.…”

Section: Methods For Detection Of Islandingmentioning

confidence: 99%

“…Because of this concern, the standard over/under voltage and frequency protective devices alone are generally considered to be insufficient anti-islanding protection. A mapping of the NDZ of the four standard over/under voltage and frequency protection methods in the RLC load space and the DP-DQ space can be found in the literature [1,3]. As an example, the NDZ of the over/under frequency protective devices in the RLC load space is plotted in Figure 2a.…”

Section: Ndzmentioning

confidence: 99%

“…This NDZ can be changed when the inverter is operating at a non-unity power factor, but this is often undesirable from the utility's perspective, and it also requires the inverter to be capable of bi-directional power flow, which would make it more expensive. A mapping of this NDZ in the RLC load space can be found in the literature [1,3].…”

Section: Ndzmentioning

confidence: 99%

“…However, for RLC loads, it is possible for the THD of v a to be less than 5%, because the parallel RLC circuit can exhibit low-pass characteristics that attenuate the higher frequencies. It is therefore clear that the THD threshold will have to be set lower than 5% [1]. In reality, the utility voltage distortion that we assumed to be »0 in the foregoing discussion can actually be expected to be 1-2% under normal conditions (because of the interaction of harmonic currents drawn or supplied by loads with the utility source impedance), but there are many conditions, such as the presence of power electronic converters that produce current harmonics at frequencies at which the utility system has resonance, which can cause this value to increase significantly [13].…”

Section: Weaknessesmentioning

confidence: 99%

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Evaluation of Islanding Detection Methods for Utility-Interactive Inverters in Photovoltaic Systems

Bower¹,

Ropp²

2002

280

281

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This report describes the various methods and circuits that have been developed to detect an islanding condition for photovoltaic applications and presents three methods that have been developed to test those methods and circuits. Passive methods for detecting an islanding condition basically monitor parameters such as voltage and frequency and/or their characteristics and cause the inverter to cease converting power when there is sufficient transition from normal specified conditions. Active methods for detecting the island introduce deliberate changes or disturbances to the connected circuit and then monitor the response to determine if the utility grid with its stable frequency, voltage and impedance is still connected. If the small perturbation is able to affect the parameters of the load connection within prescribed requirements, the active circuit causes the inverter to cease power conversion and delivery of power to the loads. The methods not resident in the inverter are generally controlled by the utility or have communications between the inverter and the utility to affect an inverter shut down when necessary. This report also describes several test methods that may be used for determining whether the anti-islanding method is effective. The test circuits and methodologies used in the U.S. have been chosen to limit the number of tests by measuring the reaction of a single or small number of inverters under a set of consensus-based worst-case conditions. FOREWORDThis report has been prepared as part of Sandia National Laboratories' Photovoltaic Systems Research and Development work for the U.S. Department of Energy. Sandia is the DOE's lead laboratory for photovoltaic systems research. The development and approach for accomplishing meaningful systems goals for the nation's photovoltaic program and the photovoltaic industry is defined through five technical objectives: (1) reduce the life-cycle costs; (2) improve the reliability; (3) increase and assure the performance and safety of fielded systems; (4) remove barriers to the use of the technology; and (5) support market growth for commercial U.S. photovoltaic systems. This evaluation of the various islanding detection methods for photovoltaic inverters and utility-interactive power systems complements Sandia's photovoltaic inverter development and evaluation goals, provides valuable information for standards and codes input, and summarizes the strengths and weaknesses of the developed anti-islanding methods available today. ABSTRACTThis report describes the various methods and circuits that have been developed to detect an islanding condition for photovoltaic applications and presents methods that have been developed to test those methods and circuits. The methods described are separated into three categories. They are:

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Section: Methods For Detection Of Islandingmentioning

confidence: 99%

Section: Methods For Detection Of Islandingmentioning

confidence: 99%

Section: Ndzmentioning

confidence: 99%

Section: Ndzmentioning

confidence: 99%

Section: Weaknessesmentioning

confidence: 99%

See 3 more Smart Citations

Evaluation of Islanding Detection Methods for Utility-Interactive Inverters in Photovoltaic Systems

Bower¹,

Ropp²

2002

280

281

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Grid Integration of Quasi‐Z Source Based PV Multilevel Inverter

Liu

Abu‐Rub

et al. 2016

Impedance Source Power Electronic Converters

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International harmonization of grid connection guidelines: adequate requirements for the prevention of unintentional islanding

Woyte

Brabandere

Dommelen

et al. 2003

Progress in Photovoltaics

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2Photovoltech SA, c/o IMEC vzw, B-3001 Leuven, Belgium Islanding is still one of the major controversial subjects in the international harmonization of grid connection requirements for distributed generation, and particularly photovoltaics. As long as islanding is not intended in order to back up a loss of mains, it should be avoided. The present study reviews the theory of unintentional islanding and assesses the probability of occurrence of the phenomenon, based on previous studies and theoretical considerations. While islanding is virtually impossible if only a small number of distributed generation units is connected to a distribution grid, with higher distributed generation densities, the possibility of islanding becomes realistic. The risk associated with unintentional islanding is estimated, and adequate requirements for functional safety of protection devices are determined in order to ensure the necessary additional degree of safety to be introduced by an islanding prevention device. Finally, a fundamental set of requirements with regard to islanding, to be included in an international grid connection guideline, is derived from the study.

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Prevention of islanding in grid-connected photovoltaic systems

Cited by 115 publications

References 20 publications

Evaluation of Islanding Detection Methods for Utility-Interactive Inverters in Photovoltaic Systems

Evaluation of Islanding Detection Methods for Utility-Interactive Inverters in Photovoltaic Systems

Grid Integration of Quasi‐Z Source Based PV Multilevel Inverter

International harmonization of grid connection guidelines: adequate requirements for the prevention of unintentional islanding

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