Patent ID: 8751177

Claim:
A method for estimating the frequency of a measured three-phase voltage (ν αβ ) comprising: measuring the three-phase voltage; and calculating estimates of a fundamental frequency voltage component ({circumflex over (ν)} αβ,1 ) and a difference ({circumflex over (φ)} αβ,1 ) between positive and negative sequence components of a fundamental frequency voltage, from an error ({tilde over (ν)} αβ ) between the measured three-phase voltage (ν αβ ) and at least one of the calculated estimates of the fundamental frequency voltage component ({circumflex over (ν)} αβ,1 ) and from an estimate of an angular frequency ({circumflex over (ω)} 0 ) of the fundamental frequency voltage component; generating at least a clean electrical signal corresponding to the measured three-phase voltage based on the estimates of the fundamental frequency voltage component ({circumflex over (ν)} αβ,1 ) wherein the estimate of the angular frequency ({circumflex over (ω)} 0 ) of the fundamental frequency voltage component is calculated from at least one of the estimated differences ({circumflex over (φ)} αβ,1 ) and from the error ({tilde over (ν)} αβ ) between the measured three-phase voltage and at least one of the calculated estimates of the fundamental frequency voltage component.