  The paper presents a comprehensive model of Continuously Variable Series
Reactor (CVSR) in the Gyrator-Capacitor (G-C) framework. CVSR is a device
capable of controlling the reactance in an ac circuit using the nonlinear
characteristic of ferromagnetic core. Bias magnetic flux produced by a dc
winding can be used to regulate the equivalent ac reactance for various
applications, such as power flow control, oscillation damping, or fault current
limiting. A novel variant of CVSR that features gapless ferromagnetic core and
a split two-coil ac winding is considered. Its nominal reactance is entirely
determined by leakage fluxes. The Gyrator-Capacitor (G-C) approach is used to
model the interface between the magnetic, electronic, and electric circuits, to
maintain consistency of active and reactive powers in these circuits and allow
additional flexibility. For accurate representation of the gapless CVSR, in
addition to a realistic nonlinear and lossy core, elaborate models of different
flux leakages are given. Results from analyses for a range of distances between
the coils of the ac winding at different bias currents are presented.
