Effects of P/f and Q/V regulations on anti-islanding detection methods in distribution networks

The diffusion of distributed energy resources (DERs) is continuously increasing and changing the structure of medium and low voltage (MV and LV) distribution networks. In this scenario the concern and the probability of unintentional islanding operations have increased due to the recently updated international standard for generator connection, which in particular require wider voltage and frequency protection thresholds and local P/f and Q/V to support the droop capabilities. Active ant-islanding detection methods have been widely used for grid-connected inverter-based DERs, such as frequency shift based protection systems. This work focuses on the performance of this active anti-islanding detection method combined with the DERs connection requirements stated by the most recent grid codes. Moreover, it describes a hardware in the loop (HIL) test-bed, where the effect of the active anti-islanding method and the droop curves on a physical interface protection system (IPS) have been tested. The obtained results emphasize the importance of having a coordination between the islanding protection system and the standard requirements for new certification procedure and connection rules for upcoming guidelines and standards.