Islanding detection in smart grids

All distributed generators (DG), especially those connected to low voltage distribution grids are required to detect islanding conditions. The methods for detecting islanding are classified in three main categories: passive, active and communication based. Passive methods are based on grid monitoring, are easy to implement but have a large non-detection zone in the case local generation meets the load demand. Active methods, which are commonly used today, may reduce the non-detection zone but in the case of large amount of DGs installed, power quality problems are foreseen. The communication based methods are seldom used today mainly because of high cost of communication. However, if the islanding detection schemes can use the communication infrastructure to be deployed for smart grids, e.g. for metering, feeder automation, etc. the communication based methods will become cost competitive with the active methods without their weaknesses. This paper focuses on communication based methods and analyzes the influence of bidirectional power flow on the existing methods. The paper also proposes a new method to be used in a smart grid infrastructure.