Enhancing the Voltage Stability and Resilience of a Microgrid Using FACTS Devices

The rise of microgrid (MG) deployments in many countries worldwide are bringing different problems associated with their operation and control. MGs can be operated in two modes: grid-connected mode or islanded (autonomous) mode. When the MG isolation takes place, the system dynamics and control actions must respond safely and reliably so that its transition to the islanded operating mode can ensure the operational resilience. In this situation, FACTS (flexible ac transmission system) technology can be applied to ensure a good operational performance of the MG to mitigate problems related to voltage control and stability. In this paper, FACTS devices such as SVC (static Var compensator) and DSTATCOM (distribution static compensator) are comparatively studied in order to know the features and operational responses to improve the dynamic voltage stability (DVS) in the MG transition from the grid-tied to the isolated operation. Results obtained show that these FACTS devices operating in coordination with the MG distributed generation systems can improve considerably the DVS and operational resilience. Results are satisfactory and their improvements are presented through dynamic simulations in time domain and using proposed metrics related to the DVS and the MG operational resilience.