Reactive Power Sharing Study of an Islanded Microgrid in DIgSILENT PowerFactory

In an islanded microgrid, it has been reported that owing to the nature of low reactance/resistance ratio line impedances, additional provision is usually required at the primary/secondary control level to maintain an accurate power sharing among DERs. Several microgrid-theme techniques such as virtual output impedance methods and adjustable power dispatch methods have been reported but most of them had only been investigated using heavily simplified networks in first principle simulation packages such as Matlab. However, in a large-scale microgrid with many DERs, it has become increasing apparent that the nature of interaction among the DERs on, for example, power sharing performance or individual controller interaction, is becoming important to be known in advance. Hence, this work develops an inverter-based DER model suitable for microgrid studies in the DIgSILENT PowerFactory simulation environment. A power sharing study based on a four-DER islanded microgrid with adjustable virtual output impedance scheme and on the use of standard P-f and QV droop scheme is presented here to demonstrate the viability of the developed model and platform.