Adaptive Estimation of Three-Phase Grid Voltage Parameters Under Unbalanced Faults and Harmonic Disturbances

In this paper, we present an adaptive observer-based, closed-loop feedback method to estimate three-phase grid voltage parameters, including frequencies, amplitudes, and phase angles under grid unbalanced faults and harmonic voltage disturbances. We treat the three-phase grid voltage signal as a solution of a parameterized dynamic system involving the unknown parameters-the fundamental and harmonic frequencies. Based on the parameterized dynamic model thus obtained, an adaptive observer is then proposed for achieving asymptotic estimation of the three-phase grid voltage parameters, that is, estimations of frequencies, amplitudes, and phase angles with zero steady-state error. This conclusion is proved rigorously by means of the Lyapunov stability theory, passivity, and La Salle's invariance principle. Both numerical simulations via MATLAB and dSPACE-based experiments are conducted to demonstrate the effectiveness and performance of the proposed estimation scheme.