Improved fault tolerance of active power filter system

This paper investigates the utilization of a relatively simple topology that provides fault-tolerant operation for a three-phase system containing a shunt active power filter. With such a topology, when one of the filter converter legs is lost, the filter can still operate by connecting the grid neutral to a fourth converter leg. The structure proposed and the operating principles of the system are presented. The system model under fault condition is derived and a suitable control strategy is proposed. Experimental results are presented to demonstrate the correctness of the proposed solution.