Estimation of Single-Phase Grid Voltage Parameters With Zero Steady-State Error

An adaptive observer-based approach is presented to estimate single-phase grid voltage parameters under harmonic disturbances. By treating the grid voltage as a dynamic system with unknown parameters related to the system frequencies, we build a parameterized dynamic model, and then, develop adaptive observers for the estimation of the grid voltage parameters including frequency, amplitude, and phase angle with zero steady-state error. The contributions of this paper are twofolds: 1) when the grid involves only fundamental voltage, a third-order adaptive estimator is derived by observer design combined with the notion of passivity. It is shown that the third-order adaptive observer can estimate the grid voltage parameters without steady-state error; and 2) when the grid voltage involves harmonic disturbances, we design a higher order adaptive observer to estimate the grid voltage parameters. Passivity and Lyapunov-based arguments ensure that the proposed method also achieves zero steady-state estimation error. Simulations and experiments are given to validate the effectiveness of our estimation strategies.