Overview of anti-islanding algorithms for PV systems. Part II: active methods

This paper offers an overview of the active methods used for islanding detection. The inverter control algorithm is based on the use of harmonic compensators in order to create ideal working conditions (i.e. the PV-system produces a sinusoidal current and reject grid harmonies). This condition is the indispensable starting point to implement active istanding detection methods. In fact these methods are based on the perturbation of the ideal conditions (e.g. the injection of active/reactive power, the injection of current harmonics, or the insertion of an external capacitor). All the reported algorithms are carefully analysed in their advantage and drawbacks and the considerations are validated by tests results obtained in accordance with the IEEE Std. 929-2000 procedure.