This study is concerned with presenting control strategy for interlink converters in hybrid microgrids. When both ac microgrids (AC-MGs) and dc microgrids are in the vicinity of each other, they can be interconnected via ac-dc converters, known as ICs, making it possible to exchange energy between two grids. Common methods employed in IC control strategy use frequency variation and CCM in their structure. This method requires the frequency variation at IC ac-side to be large, leading to poor power quality and stability of AC-MG. Furthermore, CCM does not directly regulate the IC ac-side voltage, which again deteriorates the IC ac-side voltage quality. The proposed strategy is based on droop method, similar to what is used in the autonomous control of sources in an AC-MG. This technique uses voltage-controlled method and does not need frequency measurement in its structure. This considerably improves the voltage quality of AC-MG. The derivation of appropriate droop characteristic is explained. Time-domain simulation is used to verify the performance of the proposed method. The small-signal stability of the system is studied. It is shown how by introducing a proper virtual impedance, the small-signal stability of the system can be improved.
展开▼
