A passive islanding detection technique based on envelope of derived signal using hilbert transform

Microgrid islanding comprises maintaining stable voltage, frequency, and load-generation balance, alongside difficulties in fault protection and seamless grid transitions. The failure of islanding detection methods causes system instability, reclosing failure of a circuit breaker, risk to security personnel, and damage to load-side equipment. In this work, an islanding detection technique (IDT) based on an envelope of a derived signal (EDS) is proposed for a grid-connected distributed power generating system. The objective of the proposed technique aims for quick and accurate detection of islanding including less non-detection zone, and its effectiveness in non-islanding scenarios. EDS is procured using voltage measured at the point of common coupling. The proposed method swiftly detects islanding occurrences across a spectrum of active and reactive power mismatch including zero power mismatch due to availability of local measurement of signals. This IDT effectively identifies islanding events in cases of shifts in irradiance and unbalanced loads amidst noise. It has no power quality concerns and remains quiet in non-islanding events such as DG disconnection, different fault scenarios, feeder disconnection, and switching of nonlinear, capacitive, RLC, and inductive loads, etc. The impact of the fault detection zone and non-detection zone on the proposed IDT is also explored. The proposed IDT is also tested on the OPAL-RT real-time platform. MATLAB 2018a software is used to model and simulate the microgrid.