Passive Islanding Detection Method for Grid-Connected Inverters Based on Closed-Loop Frequency Control

Abstract

Islanding detection is one of the frontier research problems in the study of distributed grid. The non-detection zone of traditional passive detection method is large, and existing active detection methods for non-detection zones are complicated. Aiming at the above problems, this paper proposes a novel passive islanding detection method with the help of closed-loop frequency control (CFC). In this new method, a high-frequency impedance detection method is combined with CFC to prevent the occurrence of islanding, and the frequency tracking principle and high-frequency impedance characteristics of the CFC are analyzed. Load impedance characteristics under different islanding conditions are also discussed. Simulation and experimental results show that proposed method is able to detect the occurrence of inverter disconnection quickly and accurately, and non-detection zone is also eliminated.