I. Introduction
Studies indicate that about 13% of the generated powers in the power system are wasted in distribution networks. Because most system components including electrical loads consume reactive power, reactive currents percent of these losses to allocated. By increasing the flow of reactive loads, system Losses also increasing. One of the most common methods for solving this problem is to use shunt capacitors. By using shunt capacitors, improve the voltage profile and reduce system losses. In addition by compensation of consuming reactive current, release the capacity of lines and increase active power transfer capability [1]. Determine the location and optimal sizing of capacitors can be obtained by solving an optimization problem. Nowadays in solving different optimization problems, often innovative and intelligent methods have been used. The following are some examples of the optimization techniques which are used in solving problem of optimal capacitor placement in the distribution network.