Internal Voltage Equivalent RMS Models of Wind Generation for Transient Stability Assessment

Root-mean-square (RMS) simulations are time-efficient in studying transient stability of large-scale power systems with inverter-based resources (IBRs). However, existing RMS models of wind turbine generators (WTGs) have simplified DC bus dynamics and inner-loop voltage feedforward terms, resulting in reduced assessment accuracy. This paper develops a new internal voltage vector-based RMS model for Type-III WTGs and improves the existing internal voltage vector-based RMS model of Type-IV WTGs to accurately emulate synchronization dynamics under large-signal disturbances. Both WTG models integrate converter and control dynamics through equivalent circuits. For Type-III WTGs, the proposed model enables direct initialization of rotor variables, while for Type-IV WTGs, imperfect voltage feedforward and DC dynamics are incorporated to enhance accuracy. The proposed RMS models show desired performance in critical clearing time (CCT) assessment when compared to detailed EMT models.