Control and stability analysis of inverter-dominated autonomous distributed generation power systems

摘要

In distributed generation (DG), the voltage source inverter provides excellent control capabilities which are absolutely necessary, especially when DG is in stand-alone mode. As a consequence, the stability analysis of an autonomous DG system with the controllers incorporated is a challenging issue. In the present paper, based on the accurate complete power system/inverter model and adopting the well-known and practically used cascaded controller structure, a rigorous stability analysis is conducted. Particularly, in this scheme, the inner-loop controllers are considered to be fast proportional-integral (PI) current controllers with decoupling terms and the outer-loop ones to be slower standard PI controllers that provide the current references of the inner-loops in accordance to the frequency/voltage regulation tasks. As it is proven, the system with the fast inner-loop current controllers included, is globally stable and converges at steady state to the desired nonzero equilibrium. The overall analysis is based on the input-to-state (ISS) notion and its extensions while Lyapunov techniques are applied on the full-order system. Thus, the stability of this kind of controllers, proven up to now only for a simple inverter device, it is effectively guaranteed for a complete DG system. As expected, the simulation results of such a complete system fully verify the theoretical analysis.