Please cite this article in press as: P. Sarkar, et al., An ant colony system based control of shunt capacitor banks for bulk electricity consumers, Appl. Soft Comput. J. (2016), http://dx.doi.org/10.1016/j.asoc.2016.02.032 ARTICLE IN PRESS G Model ASOC 3491 1–15 Applied Soft Computing xxx (2016) xxx–xxx Contents lists available at ScienceDirect Applied Soft Computing j ourna l h o mepage: www.elsevier.com/locate/asoc An ant colony system based control of shunt capacitor banks for bulk electricity consumers Parna Sarkar a Q1 , Arijit Baral b , Konika Das (Bhatacharya) a,∗ , Prasid Syam a a Department of Electrical Engineering, IIEST, Shibpur, Howrah 711103, India b Department of Electrical Engineering, Indian School of Mines, Dhanbad, Jharkhand 826004, India a r t i c l e i n f o Article history: Received 18 February 2016 Accepted 22 February 2016 Available online xxx Keywords: Ant Colony System DSP Genetic algorithm Optimized switching of SCBs True power factor Total harmonic distortion VAR control a b s t r a c t The present work focuses on the formulation of an optimization algorithm based on Ant Colony Search (ACS) technique operational from a Blackfin DSP microcontroller platform. This intelligent algorithm enables switching of appropriate Shunt Capacitor Banks (SCBs) in installations of bulk consumers of elec- tricity to improve their power factor. The application is mainly targeted on cold storages, rolling mills, traction substation and steel plants in India, where SCBs are installed over a long period in an unplanned manner. Unawareness of the impact of energy savings coupled with the fiscal incapability of these users make them unable to install costly power electronic devices for p.f. control ACS based embedded con- troller is sensitive to unpredictable load changes and selective capacitors switching cause optimal VAR control with minimum stress to the system. Employing the distributed computational model based on ACS becomes an ideal tool for the combinatorial optimization problem to select a best combination within a bank of varying sizes and varying status signifying dynamically changing search space. This low cost device will reduce the penalty billing of consumers by improving the p.f. and improved metered reading. The use of this device will lead to permeation of technology to the strata which needs it most making energy management possible without any human intervention. © 2016 Elsevier B.V. All rights reserved. 1. Introduction 1.1. Brief background of the problem Optimizing the reactive power injection is an important aspect Q4 for the electric power system’s economical and safe operation. Reasonable distribution of reactive compensation capacity in the form of switched capacitor banks, static var controllers is the pre- condition of realizing voltage and reactive VAR controlling. It can reduce the power loss, improve the power factor and improve the voltage quality, and is helpful for improving the stability of the system. Conventionally, Static Var Compensators (SVCs) have been used in conjunction with passive filters at the distribution level for reactive power compensation and mitigation of power quality problems. SVCs using shunt capacitor banks are installed in substa- tions near the loads are economical reactive power compensators with fast switching speed using current limiting reactors which ∗ Corresponding author. Tel.: +91 9339300765; fax: +91 3326685186. Q2 E-mail addresses: parna.mailbox@gmail.com (P. Sarkar), baral arijit@yahoo.com (A. Baral), poopoolee50@hotmail.com (K. Das (Bhatacharya)), prasidsyam@yahoo.co.uk (P. Syam). minimize the switching transients [1]. This switching strategy of shunt capacitor banks at the consumer end will help the consumer and utility simultaneously keeping the VAR requirement from the utility to the minimum. With an improved p.f. and voltage profile, in a dynamically changing load environment by utilizing the avail- able resources (i.e. SCBs) an efficient utilization of electrical energy is possible. Transients generated due to switching of capacitor are difficult to analyze using phasor analysis or other simplified analy- sis due to system frequency dependencies and non-linearities [2]. The high inrush currents can cause damage to the capacitors of the capacitors bank and weld the contacts of the switch together. The problems of the capacitive inrush currents and ways to reduce the magnitude of the inrush current are major concern during switch- ing of capacitor banks [3]. The process of optimization of reactive power compensation using shunt capacitor banks is a non-linear integral programming problem [4] dealing with the control of dis- persed variables [5]. 1.2. Relevance in the Indian electricity distribution system The electricity consumers connected to the Distribution System to the State Electricity Boards in Hooghly and Burdwan district of West Bengal, India comprise of rolling mills, cold storage and http://dx.doi.org/10.1016/j.asoc.2016.02.032 1568-4946/© 2016 Elsevier B.V. All rights reserved. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58