Impact of Different Types of DC Bias Sources on the Effective Impedance of a CVSR

Continuously Variable Series Reactor (CVSR) has the ability to change the total reactance in an ac circuit using the nonlinear characteristic of a ferromagnetic core, shared by windings connected to the ac and a bias dc circuit. The bias magnetic flux produced by the dc winding can regulate the equivalent ac inductance to control power flow, damp oscillations, or limit fault currents. This paper is devoted to simulating the impact of different dc bias control circuits on a three-phase CVSR, in particular, the impact on its equivalent ac inductance during normal operating conditions in different ferromagnetic states. Four different bias dc control source models are considered: an ideal current and voltage source, and two realistic dc sources with power electronics-based converters. The Gyrator-Capacitor approach is used to model the interface between the magnetic, electric, and electronic circuits.