Enhanced DDSRF based vector control of grid side converter using single AC side current sensor under unbalanced grid conditions

This paper deals with vector control of grid-connected converter under unbalance grid conditions using single AC side current sensor. DDSRF based decoupling technique is used for decoupling of grid voltage and enhanced DDSRF is used for decoupling of grid current in the revolving d⁺-q⁺ and d^--q^- frames. In the presented method, the stationary α-axis current is simply proportional to sensed r-phase current and β-axis current is estimated by filtered reference quantities of current controllers. The delay is introduced in reference quantity by filtering so that it can be used together with feedback quantities which are already delayed by low pass filter. Completely decoupled component based positive and negative sequence model of the grid side connected system is presented in this paper. The proposed algorithm is verified by extensive MATLAB simulation results.