Research Article Optimal Siting and Sizing of Multiple DG Units for the Enhancement of Voltage Profile and Loss Minimization in Transmission Systems Using Nature Inspired Algorithms Ambika Ramamoorthy 1 and Rajeswari Ramachandran 2 1 Department of Electrical Engineering, Anna University, Chennai, Tamil Nadu 600 025, India 2 Department of Electrical Engineering, Government College of Technology, Coimbatore, Tamil Nadu 641 041, India Correspondence should be addressed to Ambika Ramamoorthy; rambi 2004@yahoo.co.in Received 29 April 2015; Revised 3 September 2015; Accepted 17 December 2015 Academic Editor: Adnan Parlak Copyright © 2016 A. Ramamoorthy and R. Ramachandran. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Power grid becomes smarter nowadays along with technological development. Te benefts of smart grid can be enhanced through the integration of renewable energy sources. In this paper, several studies have been made to reconfgure a conventional network into a smart grid. Amongst all the renewable sources, solar power takes the prominent position due to its availability in abundance. Proposed methodology presented in this paper is aimed at minimizing network power losses and at improving the voltage stability within the frame work of system operation and security constraints in a transmission system. Locations and capacities of DGs have a signifcant impact on the system losses in a transmission system. In this paper, combined nature inspired algorithms are presented for optimal location and sizing of DGs. Tis paper proposes a two-step optimization technique in order to integrate DG. In a frst step, the best size of DG is determined through PSO metaheuristics and the results obtained through PSO is tested for reverse power fow by negative load approach to fnd possible bus locations. Ten, optimal location is found by Loss Sensitivity Factor (LSF) and weak (WK) bus methods and the results are compared. In a second step, optimal sizing of DGs is determined by PSO, GSA, and hybrid PSOGSA algorithms. Apart from optimal sizing and siting of DGs, diferent scenarios with number of DGs (3, 4, and 5) and  capacities of DGs ( alone,  alone, and  and  both) are also analyzed and the results are analyzed in this paper. A detailed performance analysis is carried out on IEEE 30-bus system to demonstrate the efectiveness of the proposed methodology. 1. Introduction Today, the power grid is transforming and evolving into a faster-acting, potentially more controllable grid than in the past. Tis so-called smart grid will incorporate new digital and intelligent devices to replace the existing power network [1]. Tis grants an opportunity for new innovations and modernizations. Te massive penetration of distributed generation into electric grid is one of the salient features of smart grid. But the integration of DGs perturbs the power fow and voltage conditions of the network. So, voltage regulation is one of the major issues to be addressed [2]. Te 16% of global fnal energy consumption comes from renewable sources during 2012, with 10% coming from traditional biomass, 3.4% coming from hydroelectricity, and the remaining 2.6% coming from new renewable sources like wind, solar power, and so forth [3]. Solar power takes the prominent position among all other sources due to its continuous availability and cost efective- ness. Solar energy is available in abundance [4]. But there are several challenges in adding renewable energy sources into the conventional grid [5]. Te size and location of DGs are the crucial factors in the application of DG for loss minimization [6]. One of the key requirements for reliable electric power system operation is the balancing of reactive power supply and demand to maintain adequate system voltages. Lack of sufcient reactive power supplies can result in voltage instability. Te peripheral method of balancing the reactive Hindawi Publishing Corporation e Scientific World Journal Volume 2016, Article ID 1086579, 16 pages http://dx.doi.org/10.1155/2016/1086579