Unified Power Flow Controller (UPFC) is one of the most viable and important Flexible AC Transmission Systems (FACTS) devises. Application of UPFC in single machine and multi machine electric power systems has  been investigated with different purposes such as power transfer capability, damping of Low Frequency Oscillations (LFO), voltage support and so forth. But, an important issue in UPFC applications is to find optimal parameters of UPFC controllers. This paper presents the application of Unified Power Flow Controller (UPFC) to enhance dynamic stability of a multi-machine electric power system. A supplementary stabilizer based on UPFC (like power system stabilizer) is designed to reach the defined purpose. An intelligence optimization method based on Simulated Annealing (SA) is considered for tuning the parameters of UPFC supplementary stabilizer. Several nonlinear time-domain simulation tests visibly show the ability of UPFC in damping of power system oscillations and consequently stability enhancement.

1. Al-Awami A (2007) A particle-swarm based approach 

of power system stability enhancement with UPFC. 

Electrical Power and Energy Sys. 29, 251-259.

2. Eldamaty AA, Faried SO and Aboreshaid S (2005) 

Damping power system oscillation using a Fuzzy 

logic based unified power flow controller.  IEEE 

CCGEI 2005 1, 1950-1953. 

3. Faried SO and Billinton R (2009) Probabilistic 

technique for sizing FACTS devices for steady-state 

voltage profile enhancement.  IET Generation, 

Transmission & Distribution. 3, 385 – 392. 

4. Farrag MEA and Putrus G (2011) An on-line training 

radial basis function neural network for optimum 

operation of the UPFC.  European Transactions on 

Electrical Power. 21, 27-39.

5. Guo J and Crow ML (2009) An improved UPFC 

control for oscillation damping. IEEE Transactions on 

Power Sys. 25, 288 – 296. 

6. Hao J, Bao SL, Yi-Xin N and Chen C (2008) 

Improvement of transient stability by unified power 

flow controller based on hamiltonian system theory. 

European Transactions on Electrical Power. 18, 617–635.

7. Hingorani NG and Gyugyi L (2000)  Understanding 

FACTS. IEEE Press.  

8. Jiang S, Gole AM, Annakkage UD and Jacobson DA 

(2010) Damping performance analysis of IPFC and 

UPFC controllers using validated small-signal models.  IEEE Transactions on Power Delivery. 26, 446-454. 

9. Jiang X, Chow JH, Edris A and Fardanesh B (2010) 

Transfer path stability enhancement by voltagesourced converter-based FACTS controllers.  IEEE 

transactions on Power Delivery. 25, 1019 – 1025. 

10. Kundur P (1993) Power system stability and control. 

McGraw-Hill, Inc. NY. pp: 700-822.

11. Mahran AR, Hogg BW and El-sayed ML (1992) Coordinate control of synchronous generator excitation 

and static var compensator.  IEEE Trans. Energy 

Conversion. 7(4), 615-622.

12. Mehdi Nikzad, Shoorangiz Shams Shamsabad 

Farahani, Mehdi Ghasemi Naraghi, Mohammad 

Bigdeli Tabar and Ali Javadian (2011) Comparison of 

robust control methods performance in the UPFC 

controllers design. Indian J.Sci.Technol. 4 (6), 670-

676. Domain site: http://www.indjst.org.

13. Mehraeen S, Jagannathan S and Crow ML (2010) 

Novel dynamic representation and control of power 

systems with FACTS Devices. IEEE Transactions on 

Power Sys. 25, 1542-1554. 

14. Nabavi-Niaki A and Iravani MR (1996) Steady-state 

and dynamic models of unified power flow controller 

for power system studies.  IEEE Transactions on 

Power Sys. 11(4), 1937-1950.

15. Reza Hemmati, Sayed Mojtaba Shirvani Boroujeni, 

Hamideh Delafkar and Amin Safarnezhad Boroujeni 

(2011) Stabilizer design based on UPFC using 

simulated annealing. Indian J.Sci.Technol. 4 (7), 

815-819. Domain site: http://www.indjst.org.

16. Singh JG, Tripathy P, Singh SN and Srivastava SC 

(2009) Development of a fuzzy rule based 

generalized unified power flow controller.  European 

Transactions on Electrical Power. 19, 702–717.

17. Tambey N and Kothari ML (2003) Damping of power 

system oscillation  with unified power flow controller. 

IEE Generation, Transmission & Distribution. 150, 129-140. 

18. Wang HF (1999) Damping function of UPFC.  IEE 

Generation, Transmission & Distribution. 146,129-140.

19. Wang HF (2000) A unified model for the analysis of 

FACTS devices in damping power system oscillation 

Part III: unified power flow controller,  IEEE 

Transaction Power Delivery. 15(3), 978-983.

20. Zarghami M, Crow ML, Sarangapani J, Yilu L and 

Atcitty S (2010) A novel approach to inter-area 

oscillations damping by UPFC utilizing ultracapacitors. IEEE Transactions on Power Sys. 25, 404 – 412.