A fast frequency estimation method for balanced three-phase systems with harmonic distortion

The continuous monitoring of voltage characteristics in electric power systems, such as in grid-connected power converters, is required for power quality assessment and control purposes. This paper presents a fast method to estimate the fundamental frequency of the grid voltage in balanced three-phase systems containing harmonic distortion. The proposed solution is based on a fast algebraic method, which is able to calculate the frequency of a pure sinusoidal signal. Due to the presence of harmonic distortion in the grid voltage some processing is previously carried out, involving coordinate transformations and several repetitive filters. Simulation and experimental results prove the validity of the method in balanced three-phase systems containing harmonic distortion. Furthermore, a fast and accurate estimation of the frequency is obtained even in the presence of amplitude and frequency variations. The response time achieved is around half the period of the fundamental voltage component.