FBD-method based controller for shunt active power filters in marine vessels

Shunt active power filters (SAPFs) based on the Fryze-Buchholz-Depenbrock (FBD) method allow electrical power quality (PQ) disturbances related to the load current consumption to be compensated. However, SAPF controllers based on this method require a stable grid fundamental frequency in order to operate properly. In case of isolated electrical grids suffering severe PQ disturbances, which is the case of ships electrical systems, the fundamental grid frequency can be very unstable, which reduces the SAPF performance due to an erroneous evaluation of the equivalent averaged load conductance (G_e). This paper presents a new approach for the evaluation of G_e which attenuates the impact of frequency variations. As a consequence, the performance of the SAPF is improved. Simulation results are given in order to evaluate the proposed controller.