Passive Islanding Detection using Square Law Method /

Abstract

Islanding detection has a very important role in power systems because it addresses many safety problems. A novel passive method for islanding identification in a distributed system is proposed in this paper. The proposed framework is discussed in two folds. In the first fold, the modal signal is calculated from a three-phase current, and its envelope is generated using a square law device (SLD). In the second fold, variance in autocorrelation of modal current envelop (VAMCE) is utilized as a detection basis for islanding. The autocorrelation function (ACF) of modal current envelope yields various transient features, which are then used to discriminate between the islanding and non-islanding situations. The smaller non detection zone (NDZ) and accuracy are the key advantages of this method. The VAMCE varies negligibly in normal conditions, however it varies significantly during islanding conditions, making this scheme a very effective tool for the detection of island. The scheme is evaluated using several simulations under different conditions, normal and islanded. It is found that the proposed scheme is easy to implement and has better accuracy in comparison to other passive techniques.