General Steady-State Modeling and Linearization of Power Electronic Devices in AC-DC Hybrid Grid

Power electronic devices are important in the modern power system. Control functions and operational characteristics of power electronic devices bring higher nonlinearity and heavier calculation burden to power system analysis, especially in optimization problems. In this article, a general steady-state model of power electronic devices in the AC-DC hybrid grid is proposed, which considers the high voltage direct current (HVDC) connections and the flexible AC transmission systems (FACTS). Power electronic devices are equivalently represented by impedance, transformers, and controlled sources. The linearized steady-state model is derived and then the specific formulation with minimized error is presented. The effectiveness of the proposed method is verified by optimal power flow (OPF) calculation in the IEEE and Polish test systems.