Frequency and Phase-Angle Estimation Using Ordinary Least Squares

The extensive use of grid-connected power electronics converters in the most different conditions, e.g., grid voltage quality, power level and grid codes, requires a robust synchronization method in order to properly feed other converter controllers with reliable and exact information, namely the phase-angle and the magnitude of the grid voltage. The grid phase-angle is a vital variable used in almost any single- or three-phase converter. The paper proposes a synchronizer based on the Least Squares approach: using the sampled grid voltages to fit a straight line corresponding to the grid phase-angle estimation. An extensive set of simulation results, including comparative results with three other methods, covering steady state and transient conditions, is provided and demonstrates the feasibility of the proposed method. Also, a set of experimental results, obtained with a field programmable gate array platform, complements the validation of the synchronizer and its very good performance in all conditions.