Reference generator for grid connected converters without direct supply synchronization

In recent years there have been many strategies have been proposed for use of proportional plus resonant P-R controllers both in the stationary and in the synchronous reference frame that demonstrate grid-connected converter performance can be improved under non-ideal supply conditions such as supply asymmetry and supply voltage distortion. However, when employed in systems with high frequency variability such as micro-grids, the synchronization method required for operation in the synchronous reference frame or for dynamic retuning of the resonant controller may negatively impact the performance of the controller. A method is presented here based on current decomposition that uses an efficient RDFT algorithm to compute equivalent admittances and allows control of grid connected VSCs to be performed in the stationary reference frame without direct supply synchronization. In this paper the proposed method is described and then performance is evaluated for systems with high frequency variability and non-ideal supply voltage conditions.