Fault ride-through capability of hybrid AC/DC microgrids during AC and DC network faults

Abstract

This paper investigates the fault ride-through (FRT) capability of a hybrid AC/DC microgrid during both AC and DC network faults. In this investigation, commonly proposed FRT strategies for the distributed energy resources and AC and DC microgrids are implemented while the interlinking bidirectional converter is operated in power transfer mode. The investigations have shown that improvement in the AC network voltage is minimal during both AC and DC network faults. However, the DC network voltage improves and rapidly recovers after both AC and DC network faults. This is because while the AC network is relatively weak during the fault, the interlinking bi-directional converter tracks the pre-fault power reference following the fault clearance and assists with restoration of the DC bus voltage. However, this response could be detrimental if the hybrid AC/DC microgrid is operated in an islanded mode. Hence it is important to design a robust fault ride-through support scheme for the interlinking bi-directional converter in a hybrid AC/DC microgrid.