Analysis of the NDZ formulation theory of active frequency shift islanding detection method for grid-connected PV system

Active frequency drift islanding detection method is the most widely used in the distributed generator islanding detection. Now the domestic researches of islanding detection in China are base on algorithm Improvement but without very effective, because the fundamental reasons about the NDZ have not been researched and explained deeply. Therefore, the paper analyses the performances of the frequency drift islanding method from different aspects and deeply explains the reasons conducting the NDZ of the islanding detection from the aspects of load frequency characteristic and SFS method phase-frequency characteristic, which are the major factors affecting the phase-frequency characteristic of the islanding system.