Grid-Connected power converter with islanding detection and active power filter functions

A grid-connected power converter for a distributed power generation system is proposed in this paper. The functions of islanding detection and active power filter are incorporated into the control of the grid-connected power converter. The operation theory of the proposed islanding detection method is that a small perturbation is added into the amplitude of utility current only when the amplitude of the utility current is smaller than a setting value that approximates zero. The salient feature of the proposed islanding detection method is that the small perturbation for detecting islanding operation is added only when the real power between the grid-connected power converter and the load is balanced or when islanding operation occurs. Thus, the perturbation for islanding detection is less frequent than that in conventional active islanding detection methods. The computer simulation results show that the expected performance of the proposed grid-connected power converter can be achieved.