Wide Bandwidth Power Flow Control Algorithm of the Grid Connected VSI under Unbalanced Grid Voltages

The main contribution of this paper is the new wide bandwidth power flow control algorithm of the grid connected VSI under unbalanced grid voltage conditions. The algorithm is based on simple control structure and does not demand any filter for obtaining symmetrical components, e.g. notch or anti-resonant filter. Proposed control structure applies dual vector current control, based on regulation of positive and negative sequence components. The main advantages of the suggested control method are wide controller bandwidth, as well as possibility to obtain controller parameters by using standard tuning techniques. Comparing it with the previous solutions, this control strategy eliminates oscillating components in both, active and reactive power. However, as a consequence non-sinusoidal grid current waveforms will appear. The effectiveness of proposed control algorithm is verified by detailed switching simulation model.