A static synchronous compensator (STATCOM) is a an electronic-based power device that is widely used for providing fast reactive power for a power system. With a STATCOM connected in the system, the voltage sag profile during a fault will be improved. In order to estimate this voltage sag profile improvement, a traditional voltage sag profile estimation method based on a short-circuit calculation needed to be amended to incorporate the impact of STATCOM on the system bus voltage. This article presents a current source-based STATCOM model for voltage sag profile estimation, and by incorporating the operation and control constraints into the short-circuit calculation model, a mathematical voltage sag profile estimation model for a power system with STATCOMs is proposed. The proposed model is solved via a nonlinear programming–based method. Case studies based on an IEEE 30-bus system with STATCOMs are used to illustrate the feasibility and effectiveness of the proposed method.