This study presents the study of configuration, working, controller of the fundamentals of the STATCOM and significant function of each custom power devices. Flexible Ac Transmission Systems (FACTS) controller achieves fast control response time as well as providing better control than conventional control. However, Static Synchronous Compensator (STATCOM) could be seen as one of the key Flexible Ac Transmission Systems (FACTS) devices which are based on the Voltage Source Converter (VSC) technology. The capacitive and inductive compensation could be provided by the controller and could as well control output current over the rated maximum capacitive or inductive range without depending on the ac system voltage.