Making Old New Again: HVdc and FACTS in the Northeastern United States and Canada

High-Voltage DC (HVdc) applications and flexible alternative current transmission systems (FACTSs) have been integrated in the Northeastern United States and Canada power grid for almost 30 years. The development of high-power, solid-state thyristor technology in the early 1970s contributed to the development and implementation of static var compensators (SVCs) to improve system stability and voltage control. The thyristor technology also enhanced HVdc back-to-back (BtB) applications for asynchronous ac interconnection.