Modeling and Analysis of FACTS and HVDC Controllers

High‐voltage direct current (HVDC) transmission is primarily applied for long distance bulk power transmission from remote hydro and thermal stations, asynchronous interconnections, and sea‐crossing underwater cables. The flexible AC transmission system (FACTS) can be classified as: shunt‐connected controllers, series‐connected controllers, combined series‐series controllers, and combined shunt‐series controllers. Reactive power control applied to a transmission line or a network can result in several benefits involving voltage regulation, enhancement of power flow, and stability improvement. The simplest type of power scheduling control adjusts the reactance order slowly to meet the required steady‐state power flow requirements of the transmission network. Static synchronous compensator (STATCOM) is based on a voltage source converter (VSC) that injects a voltage that is synchronized to the voltage at the bus where it is connected. In AC transmission, there is no control over the power flow in a link unless FACTS controllers are used.