Voltage stability improvement, when overloading of current distribution network is leading it toward voltage collapse, has been deemed as an important criteria in networks including distributed generation units (DGs) as part of it. In this condition, DGs can be leveraged to improve reactive power through voltage control and thus, stabilizing network with respect to the voltage. In this paper, a forward-backward power flow with respect to a voltage stability index (VSI), optimal size and location of DGs within the network are to found. The proposed method are simulated on the 34-bus IEEE standard in order to cross validate the results. تفاصيل المقالة