Generator emulation controls for photovoltaic inverters

State-of-the-art inverter controls for grid-tied photovoltaic (PV) systems pose a number of challenges to grid stability if deployed on a large scale. This paper addresses large-scale integration of PV and other distributed generation (DG) into the grid. A new control scheme for grid-tied DG inverters is proposed to embed various load-following functions. This control scheme, dubbed Generator Emulation Controls (GEC), allows DG inverters to perform voltage regulation support, reactive power compensation, and fault ride-through. GEC also allows DG inverters to form scalable inverter-dominated micro-grids. These micro-grids are capable of operating in grid-tied mode or of separating and supporting an islanded load. Dynamic modeling of synchronous generators is presented, and used to guide GEC implementation. Experimental results are presented to demonstrate some of the main features of GEC.