Optimal Reactive Power Compensation by Shunt Capacitor Sizing Using Harmony Search Algorithm in Unbalanced Radial Distribution System for Power loss Minimization

Electricity demand exceeds the supply leading to regional blackout. The power generated is transmitted through a large network and significant power losses in transmission and distribution feeders. Loss reduction through various methods has the potential to yield huge savings in economic growth and environmental impact. One such effective loss minimization method is to inject reactive power by placing shunt capacitors at appropriate places with proper size. A Harmony Search Algorithm methodology is proposed in this work to identify the appropriate size of shunt capacitors by taking the objective as minimizing the cost associated with real power losses along with installation cost of shunt capacitors in an unbalanced radial distribution network. The bus voltage limits, number/size of installed capacitors at each node are taken as constraints. A two stage methodology is adopted in this work to get the solution of the optimization problem. In the first stage, the voltage stability index values at each bus is computed and the node with minimum value of voltage stability index is identified as the most receptive node to voltage slump and such a node is considered as candidate node for installation of shunt capacitors. In the second stage the HSA methodology is used to ascertain the suitable capacitor size. The backward / forward sweep algorithm based Radial distribution load flow algorithm is utilized for power flow simulation. The proposed Harmony Search Algorithm is implemented on the modified IEEE 13 and 37 bus URDN.