Bidirectional front end converter for DG with disturbance insensitivity and islanding-detection capability

This paper introduces and develops a new control strategy for the bidirectional front end converter for grid-connected distributed generation units. In the method, the switching technique directly controls the current of the voltage-source converter. The switching method is based on the evaluation of the inductor-flux error trajectory which allows to predict the next commutation instant. The control is fast and the line-current waveform is insensitive to the grid voltage perturbations or harmonics, and do bus disturbances. A new frequency detection algorithm, robust against disturbances and with fast response in case of islanding occurrence, is introduced and applied. The proposed control method has been examined under various scenarios, including mains supply faults, distorted and unbalanced grid, and IEEE 1547 anti-islanding test. The results show the feasibility and applicability of the proposed control for the considered electronically-interfaced distributed generation units.