On-line adaptive identification and cancellation of periodic disturbance with unknown parameter

This paper presents two adaptive algorithms to estimate and cancel periodic disturbances on line. One algorithm is based on a phase-locked loop structure that estimates simutaneously the phase and magnitude of the perturbation and then cancels it. Another one is based on an estimation of the phase component and the quadrature phase component of the disturbances. Approximate harmonic analysis and parameter design of the algorithms are discussed. The ability of the algorithm to reject periodic disturbances even with slowly varying frequencies is shown through simulations.