This study proposes a method for islanding detection in distributed generation systems, namely, hybrid fuzzy positive feedback (PF). The aim is to reduce the injection of disturbances during the grid-connected operation from the anti-islanding methods, particularly at the instant of load connection and, do not require adjustment of the PF gain and frequency filters. This method is designed from fuzzy inference rules and the frequency and voltage inputs are also taken into account in the design procedure. Since the classical active methods do not identify if the voltage variation arises from the islanding condition or from a power quality issue in the grid, the fuzzy PF enables the proposed methods to differentiate the islanding condition from other grid events. In contrast to classical methods that have a fixed PF gain, a dynamic fuzzy PF gain is obtained by means of the fuzzy inference rules. The classical active technique is compared with the proposed approach in terms of detection time and injected disturbances during the grid-connected operation. The simulation and experimental results are presented to demonstrate the effectiveness of the proposed approach.

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This study proposes an islanding detection method for distributed generation systems, namely frequency fuzzy positive feedback (FFPF).The goal is to reduce the injection of disturbances, from the anti-islanding methods, during the grid-connected operation, as well as standardise the PF gain, with no adjustments needed according to the type of loads. This method is designed from fuzzy inference rules and two inputs are also considered in the design procedure. Since the classical active methods do not identify whether the frequency variation arises from the islanding condition or from a power quality issue in the grid, the fuzzy PF enables the proposed method to differentiate the islanding condition from other grid events. In contrast to classical methods that have a fixed PF gain, a dynamic fuzzy gain that adapts to any type of load is obtained by means of the fuzzy inference rules. The classical active technique is compared with the proposed approach in terms of detection time and injected disturbances during the grid-connected operation. The simulation and experimental results are presented to demonstrate the effectiveness of the proposed approach.

This paper proposes a fuzzy voltage and frequency positive feedback (PF) for islanding detection in distributed generation system (DG). The proposed method is based on positive feedback in dq synchronous frame and the design methodology of the fuzzy detection is based on fuzzy inference rules. The main idea is to reduce the injection of disturbances at the point of common coupling (PCC) during the grid-connected operation. A comparison between the fuzzy algorithm and the classical methods are done. The simulation results demonstrate the effectiveness of the proposed approach.