Challenges for Loss-of-Mains Protection System in Inverter-Based Resources Applications

Ahstract-Loss-of-mains (LoM) or anti-islanding utility protection has been one of main concerts in Inverter-based Resources (IBR) applications. Nowadays, many LOM detection methods have been designed to be excessively sensitive to comply with some standards requirements which only accept tight non-detection zones (NDZ). As a result, false islanding detection events has been often observed resulting in undesirable IBR disconnections. On the other hand, recent grid -connection stan-dards have included some immunity requirements to avoid false islanding detections since they can result in electric grid. This paper presents an experimental evaluation of the immunity of some commercial IBR under different grid disturbances such as power frequency drifts and voltage sags. It was considered for this evaluation some grid-connected photovoltaic inverters which comply with Brazilian standard NBR 16149. Results show that some commercial equipment disconnect under normal voltage/frequency grid oscillations. Therefore it is demonstrated that Brazilian standards for IBR may consider additional tests to improve the resilience of the electric system.