Patent ID: 7720623

Claim:
A fixed reference frame phase locked loop system for providing estimates for an angular frequency, a positive sequence, and a negative sequence for a fundamental component of an unbalanced three-phase signal, the system adapted to be coupled to a three-phase power distribution device having a first phase, a second phase, and a third phase, the three-phase power distribution device providing a voltage for each phase, the system comprising: a voltage module connected to the three-phase power distribution device to provide a signal indicative of the value of the voltage in each phase of the three-phase power distribution device; a coordinate transformation processor connected to the voltage module for receiving the signal of the value of the voltages in each of the three-phase power distribution device and convert the measured three-phase voltage vector values into a voltage vector in αβ-coordinates; an estimator processor connected to the coordinates transformation processor, wherein the estimator processor receives the voltage vector ν αβ in αβ-coordinates, wherein the estimator processor provides the estimate voltage vector {circumflex over (ν)} αβ and the auxiliary variable {circumflex over (ψ)} αβ , both in αβ-coordinates; an adaptive processor connected to the to the coordinates transformation processor, wherein the adaptive processor receives an error signal vector {tilde over (ν)} αβ and provide an estimated angular frequency {circumflex over (ω)}; a signal reconstruction processor connected to the adaptive processor and the estimator processor, wherein the signal reconstruction processor receives the estimate voltage vector {circumflex over (ν)} αβ , the auxiliary variable {circumflex over (ψ)} αβ , and the estimated angular frequency {circumflex over (ω)}, wherein the signal reconstruction processor provides an estimated positive sequence {circumflex over (ν)} αβ p and an estimated negative sequences and {circumflex over (ν)} αβ n , αβ-coordinates; and wherein the positive sequence and the negative sequence are in a fixed reference frame coordinates.