Active anti-islanding protection method based on active power flow applied to VSI-based distributed generation

The main approach of this paper is the study of active anti-islanding techniques with positive feedback in a Distributed Generation (DG) system composed of a Voltage Source Inverter (VSI) and local loads connected in parallel. In the literature, active islanding detection methods are preferentially used because they have smaller non-detection zones compared to passive techniques. However, on these methods, continuous disturbances are injected on DG's control and degrade the power quality provided by the electronic converter. In this context, an active islanding detection technique frequency-based with positive feedback and fixed gain is discussed, based on the classical techniques. This research aims to investigate the method's performance in relation to the detection time and the injection of disturbances in the DG's control system. From this analysis, an anti-islanding technique is developed to guarantee similar efficiency to the traditional method in cases of small-power flow through the grid, even as minimize disturbances in different points of the plant operation. This technique is based on the calculation of the variable gain on the positive feedback, that is inversely proportional to the active power deviation delivered or absorbed from the grid.