Development of a Fuzzy Based Algorithm for Islanding Detection of a Grid Connected DG

In recent years, the demand for power has increased and there has been a growing demand for Renewable Energy generating units such as the wind, water, fuel cell, photovoltaic units. These energy units produce low pollution in comparison to fossil fuels. With the introduction of such Distributed Generation units, an improvement in electricity service, reliability and power quality in comparison to the power availed from the grid alone has been observed. Such environmental concerns and deregulation in market power has caused the DG units into momentum. The DG also provides a relative low capital cost in response to incremental changes in power, while placing the power source within the already existing network and sending the power back to the grid when required. Islanding occurs when a part of the distribution system turns out to be electrically disconnected from the rest of the power system, yet keeps on being energized by the DG associated with the subsystem. The formation of such power island may compromise service operation, reliability, deterioration in power and pose as a threat to the load utility. Current IEEE interconnection standards (IEEE 1547) mandate that the control and protection measures should be in place to lessen the probability of an unintentional island, and to minimize the duration of an islanding condition, if one should occur. In order to prevent such situations, the power system networks are installed with islanding detection devices. In this work a fuzzy logic controller based on islanding detection methods have been proposed and a comparison with the traditional passive islanding methods has been done to detect the Major Island formation during loss of mains. Furthermore, the controller has been configured to incorporate multi DG interfacing to the power system network attributing to detection of Minor Island formation. The controller has been configured for distinction between the load change and the islanding