Synchronization Method for Three Phase Applications

Grid synchronization is critical for a large number of systems, being difficult to achieve in variable frequency or polluted environments. This article presents a simple and fast response digital signal processing method designed to obtain utility grid synchronism. This method is based on varying the sampling frequency so as to generate sampling pulses at a frequency multiple of the main frequency and in phase with it. Even though it operates with a variable sampling frequency, a model in z-transform space is developed, which simplifies the design of the system controller. This feature makes it suitable for measuring harmonics in the utility grid and for obtaining the phase reference for applications such as on-line power converters. Design equations for a closed loop controller producing a critically damped response are also developed herein. The method has been verified conducting experimental tests under different disturbance conditions. Copyright (C) 2010 Praise Worthy Prize S.r.l. - All rights reserved.