Please cite this article in press as: B.V. Kumar, N.V. Srikanth, A hybrid approach for optimal location and capacity of UPFC to improve the dynamic stability of the power system, Appl. Soft Comput. J. (2016), http://dx.doi.org/10.1016/j.asoc.2016.09.031 ARTICLE IN PRESS G Model ASOC-3830; No. of Pages 13 Applied Soft Computing xxx (2016) xxx–xxx Contents lists available at ScienceDirect Applied Soft Computing journal homepage: www.elsevier.com/locate/asoc A hybrid approach for optimal location and capacity of UPFC to improve the dynamic stability of the power system B. Vijay Kumar a,∗ , N.V. Srikanth (Associate Professor) b a National Institute of Technology, Warangal, India b Department of Electrical Engineering, National Institute of Technology, Warangal, India a r t i c l e i n f o Article history: Received 9 October 2014 Received in revised form 19 January 2016 Accepted 21 September 2016 Available online xxx Keywords: FA CS Power loss Voltage GSA Dynamic stability UPFC Real power Reactive power a b s t r a c t In this document, the Firefly Algorithm (FA) and Cuckoo Search (CS) algorithm based on optimal location and the capacity of UPFC to improve the dynamic stability of the power system are proposed. The novelty of the proposed method is exemplified in the improved searching ability, random reduction and reduced complexity. In this regard, the generator fault affects the system dynamic stability constraints such as voltage, power loss, real and reactive power. Here, the FA technique optimizes the maximum power loss line as the suitable location of the UPFC. The affected location parameters and dynamic stability constraints are restored into secure limits using the optimum capacity of the UPFC, which in turn, has been optimized with reduced cost by using the CS algorithm. The attained capacity of the UPFC has been located in the affected location and the power flow of the system analyzed. The proposed method is implemented in the MATLAB/Simulink platform and tested under IEEE 30 and IEEE 14 standard bench mark system. The proposed method performance is evaluated by comparison with those of different techniques such as ABC-GSA, GSA-Bat, Bat-FA and CS algorithms. The comparison results invariably prove the effectiveness of the proposed method and confirm its potential to solve the related problems. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Electric power systems have been forced to work to more or less their full capacities around the world due to the environmen- tal and economic limitations to upright new generating plants and transmission lines [2,3]. The amount of electric power by safety and steadiness restraints, that can be passed on between two posi- tions via a transmission network is limited [1]. Power flow in the lines and transformers should not be allowed to increase to a level where an arbitrary incident could cause the network fall down as cascaded outages [4,5]. The system is assumed to be blocked when such a limit attains. Managing obstruction to decrease the restric- tions of the transmission network in the forceful market has, thus, turn into the central movement of systems operators [6]. It has been analyzed that the insufficient management of dealings could increase the congestion cost which is an extra burden on customers [7]. For managing the power transmission system, Flexible Alter- nating Current Transmission System (FACTS) is a fixed device that is applied [8,9]. FACTS is recognized as “a power electronic based ∗ Corresponding author. E-mail address: bairuvijaykumar@gmail.com (B.V. Kumar). system and other fixed device that present control of one or more AC transmission system parameters to develop controllability and magnify power transfer capability” [10]. The different types of FACTS devices available for this purpose includes Static Var Com- pensator (SVC), Thyristor controlled series Capacitor (TCSC), Static Synchronous series compensator (SSSC), Static Synchronous Com- pensator (STATCOM), Unified Power Flow Controller (UPFC) and Interlink Power Flow Controller (IPFC) [12]. UPFC is one of the FACTS devices among them, that can administer the power flow in trans- mission line by including active and reactive voltage component in chain with the transmission line [11,13]. New opportunities for controlling power and enhancing the uti- lizable capacity of surviving transmission lines are discharged up by the look of FACTS tools [14]. An optimal location of UPFC device allows to control its power streams for an interconnected network, and as a result to increase the system load ability [15]. Alternatively, a limit number of devices, away from which this load ability can in no way be improved, has been analyzed [16]. The optimal location and optimal capacity of a particular number of FACTS in a power system is a hinder of combinatorial revise [18,19]. Different types of optimization algorithm have been used to effort out this kind of problem, such as genetic algorithms, reproduced annealing, tabu search and etc [17,20]. http://dx.doi.org/10.1016/j.asoc.2016.09.031 1568-4946/© 2016 Elsevier B.V. All rights reserved.