Abstract: Under constantly increased electricity demands and power transactions, it is becoming more essential to enhance the system loadability of existing distribution networks such that more power transfers can be accommodated with less network expansion cost. Instead of building new distribution substations or lines, proper installation of distribution generation units can make the distribution networks accommodate more power transfers with less expansion cost. In this paper, the problem to maximize power system loadability by optimally installing DG units is formulated as an optimization problem. To reduce the complexity of the problem, the locations suitable for DG installations are first investigated with multi objective optimisation based on inertia weighted particle swam optimisation (IPSO) method with power loss index (PLI) and voltage stability index (VSI). The size of the DG is to be installed is determined from the standard analytical methods. The proposed IPSO algorithms is tested on two standard test systems, i.e. 33-, and 69- bus radial distribution systems. The proposed algorithms has been implemented using MATLAB R2010a running on Intel Core 2 Duo processor 2.93 GHz, 1.96 GB of RAM. All evaluations were carried out with self developed MATLAB codes.

Keywords: Distributed generation, Power loss index (PLI), Voltage stability index (VSI), System loadability, IPSO.