Robust stability analysis of voltage and current control for distributed generation systems

This paper analyzes the robust stability of a voltage and current control solution for a stand-alone distributed generation (DG) unit using the structured singular value or μ-framework-based method. The voltage and current control solution consists of a discrete-time sliding mode current controller and a perfect robust servomechanism problem voltage controller, which has been shown effective in transient response and harmonic minimization in previous study without considering parametric uncertainty. The stability robustness of the system and its transient performance are investigated under various tuning parameters of the controller. The analysis results presented in this paper demonstrate that the controller parameters can be tuned and verified to satisfy a certain transient performance requirement and at the same time guarantee robust stability under system parameter uncertainties and load variations.