Coordinated Volt-Var Control in Microgrids

This paper proposes a hierarchical control approach based on a centralized architecture to coordinate volt-var function in single-phase inverters distributed in 3-phase 4-wire microgrids. The manuscript novelty is the ability to detect and reduce internal microgrid node voltage levels outside the grid code requirements, avoiding active power curtailment. As a result, the overall voltage profile throughout the point of common coupling and microgrid nodes are improved, as well as the grid hosting capacity. The strategy is evaluated based on multiple simulation results, considering an 8-node low-voltage grid. The simulation results show smooth dynamics and proper operation in several simulated scenarios. Also, great contribution of the microgrid model is shown with regard to avoiding voltage violations triggered upstream or downstream from the point of microgrid connection.