A complex networks approach for sizing and siting of distributed generators in the distribution system

The use of distributed energy is gaining more importance with the advent of the smart grid, challenges of power transfer over long distances and the need to be secure and independent in energy production. In this paper, we present an analytical method, using electrical centrality, to determine the locations and sizes of distributed generators to be placed in the distribution system. Electrical centrality is a metric used in the topological analysis of power systems, that differentiates the electrical structure of the system from its topological structure. It uses the Z_bus matrix of the distribution system to determine which nodes are electrically more central to the system and indicates them as the best locations for the placement of distributed generators, with the size of the generator related to the centrality of the node but decided by exhaustive search. It is assumed that all the generation is supplied through distributed generators. We obtain the results for the 12-, 33-, and 69-node distribution systems using this method. The results indicate that the locations indicated by electrical centrality are either the end nodes or nodes closer to the end nodes in the different branches of the networks. Generally, the end nodes are the ones where the voltage drops. As a result, this placement of distributed generators definitely corrects the voltage profile. This placement successfully makes the overall system losses very small as is seen from the optimal power flow solution obtained before and after the distributed generator placement.