Modeling FACTS Devices

There are two categories in modeling Flexible AC Transmission System (FACTS) devices in power systems: steady –state modeling and dynamic modeling.

Steady-state

For Unified Power flow Controller (UPFC), you can model this device by inserting a phase shifting transformer (PAR) between two buses connected with a transmission line(s). Since a PAR controls the power transfer by adjusting its tap, this can mimic UPFC response in a given condition. Other implementation [1] includes a bus with a generator and a bus with a load, which are not connected, inserted in a transmission line where the power flow is supposedly controlled.

For a Static Var Compensator (SVC), model a generator without MW output but with MVar (Qmax and Qmin) limits. The model is basically a synchronous condenser but enough to simulate the SVC response. Normally, the output of the SVC is dependent on the bus voltage where it is connected (maintaining a certain magnitude).

For a Thyristor Controlled Static Reactor/Capacitor (TCSR/TCSC), model a series reactor/capacitor along a given transmission line in the power flow case. Note that this is basically a series compensation model and in power flow, the compensation is seen as constant in all throughout the simulation.

In any case, you must assure that no pre-contingency impact violation is produced when you add a FACTS device in the power flow model before running contingency analysis, OPF or locational marginal pricing (LMP) studies.

Dynamics

For SVC, most power system application programs (PSS/E, PSLF, and PowerWorld) apply a Static Var Compensator dynamic model (CSVGN), for example in PowerWorld [2].

For UPFC and TCSR/TCSC, for the above software packages there is no known modeling for dynamic simulations, unless a user model is developed. Most research on dynamic modeling of these devices are implemented in MATLAB or PSCAD/EMTDC.

References:
[1]    A. Kazemi, et al, “A comprehensive load flow model for UPFC and its combination with ESS.” Available: http://www.emo.org.tr/ekler/986405e39c5a796_ek.pdf
[2]   http://www.powerworld.com/files/Block-Diagrams.pdf