Application of Voltage Harmonic Distortion Positive Feedback for Islanding Detection

Conventional active islanding detection approaches are devastating to distributed generation, while passive islanding detection methods have the disadvantage of a non-detection zone. To solve these two problems, a novel islanding detection method employing positive feedback of voltage harmonic distortion is presented. By introducing a positive feedback circuit of distributed generation voltage total harmonic distortion, the area bounded between the total harmonic distortion curve and the time axis is analyzed and used as the detection criterion. Simulation tests for the novel method are conducted even under the worst scenario designated by IEEE Standard 1547. Results show that the proposed method is capable of fast and accurate islanding detection, with the grid voltage and frequency remaining in the normal range. Furthermore, this method proves to be effective in open-phase operation and is immune to false islanding. Thus, the goal of non-destructive and non-detection zone free detection can be achieved.