Modeling anti-islanding protection devices for photovoltaic systems

Applications of grid-connected photovoltaic systems are rapidly expanding, providing a viable technology for renewable energy resources. Such systems are utility interactive and one of the major difficulties in their efficient use is related to islanding phenomena connected with a possibility of supplying surplus power back to the utility grid. In detecting and preventing such situations, anti-islanding protection devices play a paramount role. In this paper, we analyze the existing techniques in order to identify a methodology with an optimum combination of characteristics. We implement the chosen methodologies in SIMULINK. Major attention is given to the phase jump detection method (PJD), and to the slip mode frequency shift method (SMS) for which we provide a detailed description of our SIMULINK implementations and their evaluations performed on the basis of their nondetection zones. We develop an experimental iterative scheme to validate the results of computational experiments obtained with the developed models, and report the results of several computational tests. (C) 2004 Elsevier Ltd. All rights reserved.