Anti-islanding protection of distributed generators with regard to sensitivity in a balance and power system stability

This paper describes development of the methods for islanding detection. Islanding of distributed generation can appear in cases of deliberate disconnection of network parts or disconnection due to fault. This article analyses the problem of distributed generation (DG) islanding in networks where islanding is not allowed. Time duration during which DG left in islanding mode must be disconnected is defined by networks automated processes (i.e. automatic reclosure). Considering the fact that future smart grids will have even bigger degree of automatisation, now is the moment to figure out how to decrease time during which DG operates in prohibited islanding mode. It is generally acknowledged that common passive antiislanding protection methods are not always reliable due to the existence of non-detection zone (NDZ) in which active and reactive power of all loads and sources in the grid are close to or in balance. Active protection methods are more reliable in islanding detection, but are more complicated, slower and add additional interference to the grid. Third option is protection methods based on communication automation process devices, but such solutions require complex and expensive communication infrastructure.