Synchronization of unbalanced three phase voltages with nonlinear estimation

Smart grid synchronization is an important concern due to the increasing deployment of Distributed Power Generation Systems. Nonlinear estimation techniques based on synchronization algorithm are proposed to track both of the voltage magnitude and phase angle of utility network. Instead of directly analyzing in natural abc coordinate frame, by resorting to symmetrical component transformation, the proposed algorithm separate the positive, negative and zero sequences into the transformed αβ stationary reference frame. Based on the results on the αβ coordinate frame, nonlinear estimation techniques are developed to track both of the in-phase and quadrature sinusoidal voltages. Matlab simulations have shown the efficacy of our proposed nonlinear estimation methods involving the Extended Kalman Filter and the Unscented Kalman Filter. It also shows that the UKF is a more accurate and reliable method for power synchronization.