Publication Type:

Journal Article


Journal of Electrical Systems, Volume 8, Number 1, p.85-94 (2012)



Automatic generation control, Controllers, Conventional-PI controller, Damping, Damping controllers, Electric control equipment, Frequency oscillations, Governor control, Optimal switching, Performance indices, PI Controller, Power control, Power oscillations, Power transient, Proportional integral controllers, Reduced frequency, Settling time, Thermal power plants, Thermoelectric power plants, Tie-line, Unified power flow controllers, Unit step, Variable structure system


This paper focuses on systematic approach towards damping the tie-line power oscillations in an interconnected thermal power plant using Unified Power Flow Controller (UPFC) with Variable Structure System (VSS) Controller. Conventionally, Automatic Generation Control (AGC) is carried out by primary governor control and secondary Proportional-Integral (PI) controller. PI controller helps to damp out tie-line power and frequency oscillations when subjected to unit step load disturbance. Ziegler Nichols' (ZN) method is used in tuning the gains of conventional PI controller and VSS controller. Optimal switching of VSS controller is carried out by the performance indices. UPFC based damping controller helps to stabilize the tie-line power oscillations of power system. The simulation indicates reduced frequency and tieline power transient with much faster settling time is obtained by using UPFC along with secondary VSS controller. © JES 2012.


cited By 1

Cite this Research Publication

K. R. M. Vijaya Chandrakala, Balamurugan, S., and Sankaranarayanan, K., “Damping of tie-line power oscillation in interconnected power system using variable structure system and unified power flow controller”, Journal of Electrical Systems, vol. 8, pp. 85-94, 2012.