Robust and Fast Three-Phase PLL Tracking System

This paper presents a simple, robust, and fast synchronization method to detect the phase angle of the positive sequence of a three-phase ac system. The algorithm was derived from a standard phase-locked-loop (PLL) circuit based on the pq theory, but a feedforward action is implemented to guarantee high dynamic performance in conjunction with a modified feedback action to reduce the phase-angle estimation error to zero. The result is a fast tracking system that improves the start-up stage and rapid input variations. It guarantees accurate phase locking and is robust with respect to ac distortions such as harmonics, subharmonics, and voltage imbalance. The control model for the proposed PLL system was based on the standard qPLL structure. A linear analysis was performed to show the benefits of the proposed solution, and recommendations are given for tuning its parameters. The proposed technique was tested and compared with other algorithms by means of simulations. The experimental and simulation results are shown and compared.