A fuzzy control strategy to damp multi mode oscillations of power system considering UPFC

Abstract

The growth of the demand for electrical energy leads to loading the transmission system near their limits. Thus, the occurrence of the LFO has increased. Low frequency oscillations (LFO) in power system occur usually because of lack of damping torque to overcome disturbances in power system such as changes in mechanical power. Traditionally, power system stabilizers (PSS) are being used to damp these oscillations. This paper investigates the stability analysis of the application of a unified power flow controller (UPFC) to enhance the damping of low frequency oscillations in a power system, in This paper presents a modified fuzzy control scheme for a UPFC such as supplementary damping controller to enhance damping. In this paper a linearized Heffron-Philips model of a power system with a unified power flow controller is developed. In order for a fuzzy rule based control system to perform well, the fuzzy sets must be carefully designed. A major problem plaguing the effective use of this method is the difficulty of accurately constructing the membership functions .the advantages of this method are their feasibility and increasing rate to damping, to show effectiveness of new fuzzy method in damping oscillation ,the proposed method is compared with a conventional method(lead-lag compensation) is presented. The validity of this method has been confirm by time domain simulation results whit Matlab. (5 pages)