Among the voltage-sourced converter-based flexible AC transmission system controllers, the unified power flow controller (UPFC) is one of the most comprehensive and versatile ones, which has ushered in new horizons in power transmission control. For proper utilization of the UPFC in power system planning, operation, and control, a power flow solution of the network incorporating UPFC(s) is a fundamental requirement. In a UPFC, there are two representative voltage sources—one each for the shunt and series converters. Moreover, in the Jacobian matrix, multiple subblocks exclusively related to the shunt and series voltage sources of the UPFC appear, and as a result, entirely new codes need to be written for computation of each of these subblocks. A UPFC can independently control three power system parameters. Normally, the SE bus voltage, the line active power flow, and the line reactive power flow comprise these three control objectives.