Digital Control Method for Grid-Connected Converters Supplied With Nonideal Voltage

When employed in systems with higher frequency variability and nonideal supply voltage, the synchronization method used in grid-connected power electronic converter control systems must be considered. A method is presented here that achieves synchronization implicitly through the use of a discrete Fourier transform in combination with the computation of an effective admittance. It is shown that the method is suitable for systems with high frequency variability as well as for systems with nonideal supply voltage including heavy voltage asymmetry.