Predictive current control for stabilizing power electronics based AC power systems

Frequency domain passivity theory is used to evaluate harmonic resonance instabilities in a system with multiple grid-tied voltage source converters (VSCs), and subsequently, a stabilizing controller using predictive current control (PCC) method is proposed to prevent such instabilities. The input admittance of VSCs using PCC can achieve passivity almost up to the Nyquist frequency. This research demonstrates that a very simple and easy implementation of PCC can extend the controller delay dependent stability range of converter side current control for VSCs equipped with LCL-filters up to that point. The alternative approaches achieved stability over similar frequency range by combining complicated active damping techniques with proportional-integral or proportional-resonant type controllers. The frequency domain analysis of the proposed PCC based method is validated via simulation and hardware experiments. The controller is experimentally shown to achieve stable operation irrespective of model imperfections.