Comparative analysis of passive islanding detection methods for grid-connected Distrubted Generators

In a grid connected Distributed Generator (DG) system, islanding is the phenomenon wherein the DG keeps on supplying power to the load despite the grid tripping. To arrest the creation of this isolated island, anti islanding techniques are devised and implemented. An acceptable islanding technique must have a quick detection time as well as low Non detection zone (NDZ) area. This paper compares and analyzes three different passive anti islanding methods - Under Voltage (UOV), Under/Over Frequency (UOF/OUF) and the Positive Sequence Impedance method. All proposed methods are simulated on a suitable test bench model, their performance measured and compared by noting the speed of islanding detection. The results and findings are presented at the end.