Optimal capacitor placement using branch and bound

Optimal capacitor placement (OCP) determines the sizing, siting, and switching of capacitors that are added to a radial distribution feeder. OCP seeks to maximize the net dollar savings resulting from the reduction in power and energy losses less the total costs of capacitors. The distribution feeder typically consists of a main branch, some lateral branches, and nodes. Nodes are points on the feeder where segment characteristics change and where electrical loads are connected. This paper presents a new OCP method that employs a branch-and-bound algorithm, which seeks to reduce the total number of possible alternative sizes and sites to test. The proposed method automatically generates combinations of capacitor banks and feeder nodes, it performs power flow analysis to determine the effectiveness of each combination, and it stores the optimal and near-optimal solutions. The switching of capacitors is based on a user-specified power level. The proposed method has been applied successfully to a test distribution feeder. The proposed method has a fast computational time because it does not require evaluating all possible alternative combinations.