Embedded limitations and protections for droop-based control schemes with cascaded loops in the synchronous reference frame

Droop based control schemes for power electronic converters have been object of extensive research in the last decade and have arguably become the most popular solution for converter control in microgrid applications. The protection from over-currents and over-voltages are critical features of control schemes for converters required to operate in both stand-alone and parallel-connected modes, but these aspects are marginally treated in literature on microgrids. This paper analyzes possible schemes that can be applied for protection and active limitations of voltages and currents in droop based controls for microgrids based on cascaded voltage and current control loops. Implementation aspects are discussed in detail and performances are compared by numerical simulations.