Fault calculations in AC-DC hybrid systems

Hybrid AC-DC systems are expected to flourish rapidly as part of the transition from conventional grid to smart grid. Effective detection, classification, and mitigation of faults in hybrid systems require accurate modelling of the entire system as a whole, and its components as well. Moreover, precise computation of fault current is an indispensable part of any fault management scheme. Such modelling frameworks have long been existing for either three-phase AC, or DC grids. However, existing algorithms turn to be inadequate in calculating the fault current characteristics in full AC-DC hybrid systems that include distributed generation sources and energy storage units. This paper reviews the complexities involved in determining fault current characteristics in such hybrid AC-DC where switch-mode power converters interface AC and DC and renewable resources are integrated in the DC subsystem.