Majlesi Journal of Electrical Engineering Vol. 8, No. 3, September 2014 15 Optimization of Fuse-Recloser Coordination and Dispersed Generation Capacity in Distribution Systems Morteza Nojavan, Heresh Seyedi, Arash Mahari, Kazem Zare Department of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran. Email: m.nojavan@tabrizu.ac.ir Received: July 2013 Revised: December 2013 Accepted: March 2014 ABSTRACT In this paper, a novel protection of coordinating optimization algorithm is proposed. Maximizing the penetration‘s dispersed generation and at the same time minimizing the fuse’s operating time are the targets. A novel optimization technique, the Imperialistic Competition Algorithm (ICA), is applied to solve the problem. The results of simulations confirm that the proposed method leads to lower operating times of protective devices and higher possible DG penetration, compared with the traditional coordination techniques. KEYWORDS: Fuse-recolser Coordination, Optimization, DG, Protection, ICA. 1. INTRODUCTION Application of DG in distribution systems has increased in recent years. This is mainly due to the reliability and environmental considerations. A comprehensive survey of DG technologies, definitions and benefits has been presented in [1]. DG’s positive and negative impacts concerning the reliability of system’s power have been studied in [2-4]. High penetration of DG may result in the incoordination of overcurrent protective devices [5]. Therefore, the overcurrent problem of protecting coordination must be solved in the presence of DG. Several researches have been performed hereof: In [5], first the fuse-recloser coordination problem has been solved. Then, the maximum possible value of DG short circuit capacity has been calculated, in order that the protecting coordinating is still valid. In [6], two cases have been studied. The first one is to determine the best DG location, to minimize. The number of fuses and reclosers incoordination for different fault locations. The second one is to change the TD of recloser to minimize the number of fuse and recloser incoordination for different fault locations. A simple adaptive overcurrent protection of distribution systems in the presence of DG has been presented in [7]. In this method, the course characteristics of the relays are updated by detecting the operating mode (grid connected or island) and the faulted section. Protective devices coordination with the presence of DG has been discussed and the fuse-fuse, fuse-recloser and relay- relay coordination have been studied regarding the Dg’s size and location. [8]. A microprocessor-based recloser has been presented in [9], to coordinate fuse-recloser in an actual distribution system with distributed generation. In [10], when a fault occurs then all the DGs will be disconnected promptly before any operating activity of protective devices.. This way, the conventional protecting coordinating is applicable. The impact of DG on the reliability of distribution systems considering protecting coordinating has been analyzed in [11]. In [12], first the effect of high DG penetration on protective devices has been studied. Then, a scheme has been proposed based on adaptive protection for different sizes, types and locations of DG to solve the problem. In [13], the optimal size of DG has been calculated using Optimal Power Flow (OPF), considering recloser fuse coordination. In [14], maximum capacity of DG at each node of the distribution system has been determined considering coordination protection. At the first stage, a single DG in the distribution system has been studied. At the second stage, two or more DGs in separate nodes have been considered. The superconducting fault current limiter (SFCL) has been used in [15], to restore the coordination of protective devices in the presence of wind-turbine generation. Coordination of the directional overcurrent relays has been studied with the DG presence in [16]. Regarding to this purpose, the impedance type of the Fault Current Limiter (FCL) is used. The optimal size of wind-turbine generator, considering voltage regulation and overcurrent relay coordination, has been calculated in [17].