Designing proper control set-point signal for PQ inverters of isolated microgrids

In this paper, the performance and transient frequency response of an islanded microgrid with two different categories of inverters are analyzed when different control set-point signals are defined for the Current Source Inverters. Voltage Source Inverters (VSIs) use a decentralized droop controller which helps preserving the power-sharing stability. Then, Current Source Inverters (CSI, also called PQ inverters) will improve the system's performance by providing extra capacity for the system to accommodate load changes. In this context, defining proper active and reactive power set-points for CSI (PQ) inverters of a microgrid is one of the necessary control designs that ensures systems integrity by providing more secure power supply to the loads. The study conducted here tries to propose different possible solution for communication link selection and definition in order to form an appropriate set-point signal. Consequently it minimizes the need for communication links as much as possible while making sure that the systems performance is acceptable. The proposed control signals are investigated and their effects on the transient response are demonstrated using an 11 bus microgrid.