Static VAR Compensator

A static VAR compensator, or SVC, is a set of electrical devices, part of the flexible AC transmission system family, that supplies fast acting reactive power to a high voltage transmission network to regulate voltage, power factor, harmonics and system stability; it works as an automated impedance matcher built from thyristor controlled reactors and capacitor banks, drawing reactive power through its reactors when the system load is capacitive and switching in its capacitor banks when the load is inductive, giving it continuously variable leading or lagging reactive output. Before SVCs, power factor correction depended on large rotating machines such as synchronous condensers or on switched capacitor banks; an SVC responds to voltage changes nearly instantaneously, and is cheaper, higher capacity, faster and more reliable than a synchronous condenser, though it costs more than mechanically switched capacitors alone. SVCs serve two main roles: regulating voltage on transmission networks, and smoothing out the voltage flicker caused by rapidly varying industrial loads such as arc furnaces.