Series capacitors (SCs) are widely used in long transmission lines to reduce the effective series impedance and increase power transfer capability. During fault conditions, SCs are subjected to overvoltages and are therefore typically protected by metal-oxide varistors (MOVs), which, due to their nonlinear conduction characteristic, conduct only when a predefined voltage threshold is exceeded, thereby limiting the electrical stress on the SC. In addition, a bypass switch is triggered when fault conditions exceed the MOV capability, fully bypassing the SC–MOV set.

Accurate modeling of the SC–MOV behavior, including conduction, bypass operation, and reclosing, is essential for reliable power system stability assessment. Recently, the Western Electricity Coordinating Council (WECC) approved a phasor-domain transient (PDT) model for SC–MOV systems based on the Goldsworthy MOV formulation, a well-established approach that has historically been used primarily for steady-state short-circuit studies. However, the application of this classical formulation within PDT simulations has not been widely documented or systematically evaluated in the literature.

This paper therefore investigates the capabilities and limitations of the SCMOV model when applied in PDT studies. The main contribution is a systematic assessment of its functionality, including conduction and bypass dynamics, and a detailed benchmarking against electromagnetic transient (EMT) simulations, which are generally regarded as the most accurate representation of system behavior. The comparison also considers operating conditions with inverter-based generation and varying grid strength. Furthermore, the results highlight the importance of detailed SCMOV parameter identification to ensure cross-domain consistency between EMT and PDT studies.