Active method for unintentional islanding detection and associated power quality issue in Japan

This study considers whether the voltage flicker (VF) caused by the frequency feedback (FFB) method with step reactive power injection can have been prevented in advance. We organised the entire process, from establishing related regulations through the development and implementation of the FFB method to the occurrence and mitigation of VF, and evaluated the rationale at each stage. From comprehensive examinations, we point out that each action seems rational and that the game changer is a Feed- in Tariff scheme. The novelty of our study lies in its long-term, comprehensive analysis, which enables the accurate identification of key factors and provides insights from real -world experiences.