Overview of Islanding Detection Methods

Islanding is detected by all distributed generations (DGs), especially those connected at secondary distribution grids. Islanding methods are mainly classified in three main categories Passive, Active, Communication based. Hybrid methods are first time discussed in this paper. These methods are under evolution and as their advantages are coming they become an important part of islanding detection techniques. Passive methods discussed are the over/under voltage (OUV), over/under frequency (OUF), monitoring of phase angle, and monitoring of harmonics in voltage methods, rate of change of phase angle difference. Active methods discussed are impedance measurement, harmonic injection and positive feedback methods. Communication based methods discussed are power line used for communication, signal generated from disconnection, SCADA based and Wide Area Measurement System (WAMS) based. Three hybrid methods are discussed and these methods are combination of active and passive methods. This paper is focused on discussion of different islanding methods and introduction of the hybrid methods.