A novel reference signal generator for active power filters based on Recursive DFT

A novel reference signal generator is proposed for active power filters. The method takes advantage of a computationally efficient Recursive DFT and it is based on extraction of the positive sequence component from the measured current with the Fortescue decomposition. The extraction of the positive sequence component ensures the correct evaluation of the active and reactive current components under both balanced and unbalanced line current conditions. Computer simulations and experimental results are presented in the paper. They demonstrate excellent dynamic performance and excellent detection accuracy of the method as compared to the commonly used d-q synchronous reference signal generators.