A SMART Power Flow Controller (SPFC) enhances the controllability in an electric power grid by using functional requirements and cost-effective solutions. Utilities that are looking for ways to enhance the controllability in their power grid by voltage regulation, phase angle regulation, line impedance regulation, fault-current limitation, and much more can benefit from using a SPFC, the heart of which is a Sen Transformer (ST) that is a new family of impedance regulating transformers. The ST is manufactured with time-tested components, such as a transformer and Load Tap Changers that offer high reliability, high efficiency, low carbon foot-print, low-cost, component nonobsolescence, high power density, interoperability and small physical foot-print, which makes it portable.