Abstract: The objective of the research is to provide the application of Generalized Average models of FACTS device, TCSC and custom power device, DVR for power system transient analysis within dynamic phasor approach. The dynamic phasor models of TCSC and DVR are evaluated through simulation of realistic network model of 3 machines 9 bus WECC system. The continuous-time large signal models of TCSC and DVR under a fault condition captured the phasor dynamics of key wave forms. It is found that the increase transient stability and improve power quality response of dynamic phasor model of TCSC and DVR, respectively are closely hugged with the detail time domain EMTP simulation. Numerical simulation of phasor dynamics with larger size steps through solving differential equation is also faster than that of EMTP. Both EMTP and theoretical framework of dynamic phasor models has been simulated using Simulink/Matlab dynamic system modelling software.