State estimation in electric distribution networks in presence of distributed generation using the PMUs

Regarding the high cost of PMU units, optimal placement and minimizing of their numbers are of great importance. Also, this paper proposes a new procedure for determining the optimal placement and less numbers of PMUs in distribution network based on the best state estimation criterion. For DSE solution, combination of Nelder-Mead (NM) simplex search and Ant Colony Optimization (ACO) algorithm have been used. The hybrid method can estimate voltage phasor at each node by minimizing difference between measured and calculated values of state variables and also, it can guarantee observability of distribution system under normal operation conditions. To demonstrate the effectiveness of new procedure, simulation studies are applied on 30-bus radial test feeder. Finally, achievement results for convergence characteristic of DSE solution and estimation error of state variables with regard to the optimal placement and numbers of PMUs in distribution test feeder have been presented.