Reactive power compensation is a main problem in the control of electric power system. Reactive power from the source increases the transmission losses and reduces the power transmission ability of the transmission lines. In addition, reactive power must not be transmitted throughout the transmission line to a longer distance. Consequently, flexible ac transmission systems devices such as static compensator unified power-flow controller (UPFC) and static volt-ampere compensator are used to ease these harms. UPFC is the mainly adaptable and composite power electronic equipment that has emerged as the vital equipment for the control and optimisation of power flow in electrical power transmission system. In this study, a d-q model-based UPFC is developed with proportional-integral (PI) and PID controller. The above controllers are simulated using MATLAB and their performance is analysed. Outcome of the analysis shows the superiority of PID control over the PI control method. Also this study presents comparative evaluation (both controllers) of dynamic response when initial and final load disturbances.