The Development of a Coordinated Anti-Islanding Protection for Collector Systems With Multiple Distributed Generation Units

This paper presents a coordinated anti-islanding protection for collector systems with multiple distributed generation units (DGUs). The presented anti-islanding protection is established based on processing the d-q-axis components of the instantaneous three phase apparent powers (s(d) and s(q)) determined at the point-of-common-coupling using the wavelet packet transform (WPT). Processing s(d) and s(q) by using WPT allows the extraction of low-and high-frequency sub-band contents. The contents of the high-frequency sub-band are used to detect and distinguish islanding events, and contents of the low-and high-frequency sub-bands are employed to define a coordination index, which is used to identify the islanded DGU(s). The presented anti-islanding protection is implemented for off-line testing using data obtained from a laboratory collector with four different DGUs. Off-line test results demonstrate accurate, fast, and reliable responses to islanding and nonislanding event(s), and accurate identification of islanded DGUs along with negligible sensitivity to levels of power delivery to the collector system.