A multi-objective gravitational search algorithm based approach of power system stability enhancement with UPFC

Abstract

On the basis of the theoretical analysis of a single-machine infinite-bus (SMIB), using the modified 
linearized Phillips-Heffron model installed with unified power flow controller (UPFC), the potential 
of the UPFC supplementary controller to enhance the dynamic stability of a power system is evaluated 
by measuring the electromechanical controllability through singular value decomposition (SVD) analysis. 
This controller is tuned to simultaneously shift the undamped electromechanical modes to a prescribed 
zone in the s-plane. The problem of robust UPFC based damping controller is formulated as an optimization 
problem according to the eigenvalue-based multi-objective function comprising the damping factor, and 
the damping ratio of the undamped electromechanical modes to be solved using gravitational search 
algorithm (GSA) that has a strong ability to find the most optimistic results. The different loading 
conditions are simulated on a SMIB system and the rotor speed deviation, internal voltage deviation, 
DC voltage deviation and electrical power deviation responses are studied with the effect of this flexible 
AC transmission systems (FACTS) controller. The results reveal that the tuned GSA based UPFC controller 
using the proposed multi-objective function has an excellent capability in damping power system with low 
frequency oscillations and greatly enhances the dynamic stability of the power systems.