Comparison of orthogonal quantity generation methods used in single-phase grid-connected inverters

This paper is concerned with the performance investigation of single-phase grid-connected inverters in which rotating reference frame control strategy is used. Single-phase grid-connected inverters have found wide applications in interfacing small renewable energy sources to the grid. Naturally the single phase structure of these systems prevents using some well-known three-phase control strategies. One method to overcome this limitation is to virtually generate an orthogonal quantity and then exploit the existing three-phase control methods. This approach requires a phase-shifting block to generate the additional control signal. In this paper, several methods used to accomplish this task are investigated and compared from the standpoints of dynamic and steady-state performance. Therefore, the complete state-space model of the system is derived and linearized for small-signal studies. The results of comparison between different approaches are given.