Operation and control of a synch invulnerable master‐slave organised islanded alternating current microgrid

Abstract

Abstract Microgrid (MG) bridges different inverter interfaced distributed energy resources (DERs) to operate and control efficiently within a grid. The multi‐master‐slave control strategy can provide robust control of inverter interfaced DERs in close proximity. The role of master DERs is significant in synchronising the slave DERs and reducing the effect of single unit failure. However, faulty master DERs and master side communication failure can also suddenly affect the synchronisation of the slave DERs. Unfortunately, previous studies on multi‐master‐slave MGs have not addressed this issue. So, in this paper, a synch invulnerable multi‐master‐slave control strategy is proposed by introducing a synch selector with the centralised secondary controller. The synch selector is designed to pick the synchronising references from the first available healthy master units while keeping other masters operational and sending the synchronising references to the slave DERs. It also significantly reduced the dependency on communication lines up to the possible extent. Real‐time simulation results are presented to demonstrate the effectiveness of the proposed control strategy. The presented results show that the unhealthy master units seamlessly can be side‐stepped, and the next possible healthy master unit can be assigned to send reference signals to the slave DERs, hence, resisting synch vulnerability. The observations also show accurate power‐sharing, full utilisation of DERs, and reliable and stable operation of the entire MG.