A Novel Passive Anti-Islanding Technique for Inverter-Based Distributed Generation Systems

With the increased popularity of distributed generation (DG) in power systems, the issue of fast and automatic detection of unintentional islanding, also known as antiislanding, has become a major challenge. Islanding condition occurs when part of the electrical power system is disconnected from the rest of the grid but is still energized by a DG unit. Conventional passive anti-islanding approaches utilize the power system parameters such as the change of voltage magnitude, frequency deviation, and voltage phase displacement. The main issue in these approaches is the dependency of these parameters on the islanding conditions and on the power system topology. This paper monitors the ripple content in the Root Mean Square Voltage value at the point of common coupling to detect islanding. The ripple content is significantly higher during islanding conditions due to the effect of inverter induced harmonics and this characteristic has been used for anti-islanding. The proposed technique was modeled in an inverter-based DG network with photo-voltaic arrays. The model was tested using a wide range of islanding and nonislanding conditions and was able to accurately detect islanding under all DG loading conditions.