PWM harmonic signature based islanding detection for a single-phase inverter with PWM frequency hopping

Distributed generation (DG) has gained popularity in recent years due to the increasing requirement for renewable power sources. A problem that exists with DG systems is the islanding of DG units that creates safety issues for personnel as well as the potential for damage to utility infrastructure. Therefore, islanding detection methods are utilized to mitigate the risk of islanded operation of DG units. A new passive method of islanding detection based on the signature of the PWM voltage harmonics is proposed. The viability of the algorithm is investigated with the use of an analytical and time domain model of the inverter and further validated with experimental results. Furthermore, an extension of the detection scheme is proposed for use in multi-inverter scenarios composed of adaptive frequency hopping to eliminate unwanted tripping.