Flower Pollination Algorithm and Loss Sensitivity Factors for optimal sizing and placement of capacitors in radial distribution systems A.Y. Abdelaziz a , E.S. Ali b,⇑ , S.M. Abd Elazim b a Electric Power and Machine Department, Faculty of Engineering, Ain Shams University, Cairo, Egypt b Electric Power and Machine Department, Faculty of Engineering, Zagazig University, Zagazig, Egypt article info Article history: Received 30 July 2014 Received in revised form 29 September 2015 Accepted 17 November 2015 Keywords: Flower Pollination Algorithm Power systems Power losses Optimal capacitor locations Loss Sensitivity Factors Distribution systems abstract In this paper, Flower Pollination Algorithm (FPA) is proposed for optimal allocations and sizing of capac- itors in various distribution systems. First the most candidate buses for installing capacitors are sug- gested using Loss Sensitivity Factors (LSF). Then the proposed FPA is employed to deduce the locations of capacitors and their sizing from the elected buses. The proposed algorithm is tested on 10, 33 and 69 bus radial distribution systems. The obtained results via the proposed algorithm are compared with others to highlight the benefits of the proposed algorithm in reducing total cost and maximizing the net saving. Moreover, the results are introduced to verify the effectiveness of the proposed algorithm to enhance the voltage profiles for various distribution systems. Ó 2015 Elsevier Ltd. All rights reserved. Introduction In distribution networks, reactive power flows cause high power losses, high voltage drop and low power factor. These effects can be reduced by optimally installing of shunt capacitors [1]. Compensation of reactive power presents the basic role in power system planning to provide compatible locations of the compensa- tion apparatus to guarantee the minimum cost of compensation with suitable voltage profiles [2]. Many techniques and optimization algorithms have been addressed in literature to deal with the problem of locations and sizing of capacitors in distribution systems. Genetic Algorithm (GA) [2], Particle Swarm Optimization (PSO) [3,4], Firefly Algorithm (FA) [5], Memetic Algorithm [6], Differential Evolutionary (DE) [7– 9], Evolutionary Algorithm (EA) [10,11], Fuzzy Logic [12–15], Hybrid Algorithm [16], Heuristic Algorithm [17–19], Cuckoo Search Algorithm [20], Plant Growth Simulation Algorithm (PGSA) [21–23], Harmony Search (HS) [24], Ant Colony Optimization (ACO) [25], Mixed Integer Non Linear Programming (MINLP) [26], Artificial Bee Colony (ABC) [27], Teaching Learning Based Opti- mization (TLBO) [28] and Direct Search Algorithm (DSA) [29] are introduced as a solution to capacitor placement problem. However, these algorithms appear to be effective to deal with this problem, they may not guarantee reaching the optimal cost due to many reasons. In [4,5,10,20–22,24], the values of capacitors are treated as a continuous value. Moreover, the suggested objective function in [6,7,23,29] is so conventional and doesn’t take all costs in con- sideration. The studies in [3,4,6,9,13,16,17,19,22–24,26] are lim- ited to small scale system. Also, some use large number of buses to compensate [2,11,24]. On the other hand, the mentioned tech- niques have their own defects and have many parameters to assign that lead to large processing time [8,12–15,27]. Recently, the Flower Pollination Algorithm (FPA) is proposed in this paper to deal with the problem of optimal capacitor placement. It has only one key parameter p (switch probability) which makes the algo- rithm easier to implement and faster to reach optimum solution. Moreover, this transferring switch between local and global polli- nation can guarantee escaping from local minimum solution. In addition, it is clear from the literature survey that the application of FPA to solve the problem of capacitor location has not been dis- cussed. This encourages us to adopt FPA to deal with this problem. FPA technique is introduced in this paper in order to minimize the investment cost of new compensation sources and the active power losses with mitigating the voltage profiles for different dis- tribution systems. The locations of the shunt capacitors problem are obtained at first by examinations the buses of higher LSF. Then FPA is introduced to decide the optimal locations and sizing of capacitors from specified buses. The effectiveness of the proposed http://dx.doi.org/10.1016/j.ijepes.2015.11.059 0142-0615/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: almoatazabdelaziz@hotmail.com (A.Y. Abdelaziz), ehabsalimalisalama@yahoo.com (E.S. Ali), sahareldeep@yahoo.com (S.M. Abd Elazim). Electrical Power and Energy Systems 78 (2016) 207–214 Contents lists available at ScienceDirect Electrical Power and Energy Systems journal homepage: www.elsevier.com/locate/ijepes