Fault Current Hierarchical Limitation Strategy For Fault Ride-through Scheme Of Microgrid

As we are increasing the number of Micro-Grids, then the utility Grid experience difficulty of high level fault current at the time of Fault Ride Through of Micro-Grids. To overcome this problem, a fault current hierarchical limitation (FCHL) strategy is proposed, which consists of four levels: 1) fault current primary limitation control (FCPLC) is based on the proportional-resonant (PR) current controller; 2) fault current secondary limitation control (FCSLC) is formulated for current generation of grid-connected inverters (GCIs) with peak fault current limitation; 3) fault current tertiary limitation control (FCTLC) is formulated for the phase angle shifting of MG’s fault current to neutralize its effect on UG’s fault current; 4) fault  current quartus limitation control (FCQLC) is developed for the coordinated operation of parallel GCIs within grid code requirement. Simulation results verify the performance of proposed strategy with a successful fault ride through while the Micro-Grid’s output fault current has a small effect on the UG’s fault current amplitude.