The global environment is degrading and all efforts are being made to reverse the situation. Power generation based on fossil fuel is partly responsible for the polluting emissions. Because of this, renewable (non-pollutant) energy sources have received a lot of attention in the power community. The cost of renewable energies is expected to fall as the demand increases. Power conversion interfaces (PEI) are needed to integrate renewable energy sources with the existing electrical power system. This paper provides a brief introduction on power conversion interfaces.

Flexible AC Transmission System (FACTS) refers to a family of power electronics-based devices designed to increase power transfer capability of power transmission system. The main objective of FACTS is to obtain AC systems with a high level of flexibility just as in high-voltage DC systems. power electronics for controlling power flow in a transmission system. This paper provides a brief introduction to FACTS devices or controllers.