A new robust phase tracking system for asymmetrical and distorted three phase networks

A new robust synchronization mechanism to detect the phase angle of the positive sequence of the supply voltage system is proposed. The algorithm relies on a feed-forward action to guarantee high dynamic performance and on a feedback action to reduce to zero the errors on the estimation due to the line frequency variations; this last have the structure of a q-phase locked loop (qPLL). A control model of the proposed PLL system is developed and recommendations are given to tune its parameters under asymmetrical and distorted utility conditions. The proposed system has been compared with the most widespread classical structures by means of simulations.