A new impedance-based approach for passive islanding detection scheme

Abstract

This paper presents a new approach for islanding detection that is based on monitoring measures of impedance at the point of common coupling (PCC). A frequency dependent model that characterizes the change in circuit topology when an island occurs is developed as a first step in systematically selecting impedance metrics and thresholds for islanding detection. To implement passive islanding detection, the monitoring operation exploits the presence of harmonic distortion in the current and voltage at the PCC as a basis for computing measures of impedance at frequencies where there is sufficient harmonic content. Unlike signals based schemes that rely on heuristics, the proposed approach is based on an analytic model that reflects the interconnection topology. The main contribution of the work is the development of an analytic model that reflects the interconnection topology of distributed generators (DGs) with the electric power system (EPS) for DGs that include power converters and DGs that do not include power converters.