Influence of load characteristics and main settings of distributed plants stabilizing functions on the undesired islanding detection

Distribution networks are increasingly hosting embedded generators, most of them converting renewable energy primary sources. These units are usually interfaced with the main network by means of static power converters. Grid codes have recently introduced stabilizing functions to engage distributed plants in supporting the main system stability during network events and consequent voltage/frequency perturbations. The paper highlights the risk of unintentional islanding, which may be concrete depending on the embedded plant operating conditions, the load characteristics and the stabilizing functions main settings. Firstly, the stabilizing effect of rotating loads is demonstrated. Secondly, the positive impact of the recently introduced intentional delay on the reactive power response in the case of voltage variations is studied. Non-detection zones in terms of generator active and reactive power are reported as final results with reference to different scenarios.